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1

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

PubMed Central

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 collection of geo-referenced multi-scale indicators that were identified by Canadian specialists and end-users as relevant for the surveillance of the public health impacts of climate change. This system was developed in a multidisciplinary context involving researchers, policy makers and practitioners, using BI and web-mapping concepts (more particularly SOLAP technologies), while exploring new solutions for frequent automatic updating of data and for providing contextual warnings for users (to minimize the risk of data misinterpretation). According to the project participants, the final system succeeds in facilitating surveillance activities in a way not achievable with today's GIS. Regarding the experiments on frequent automatic updating and contextual user warnings, the results obtained indicate that these are meaningful and achievable goals but they still require research and development for their successful implementation in the context of surveillance and multiple organizations. Conclusion Surveillance of climate-related health vulnerabilities may be more efficiently supported using a combination of BI and GIS concepts, and more specifically, SOLAP technologies (in that it facilitates and accelerates multi-scale spatial and temporal analysis to a point where a user can maintain an uninterrupted train of thought by focussing on "what" she/he wants (not on "how" to get it) and always obtain instant answers, including to the most complex queries that take minutes or hours with OLTP systems (e.g., aggregated, temporal, comparative)). The developed system respects Newell's cognitive band of 10 seconds when performing knowledge discovery (exploring data, looking for hypotheses, validating models). The developed system provides new operators for easily and rapidly exploring multidimensional data at different levels of granularity, for different regions and epochs, and for visualizing the results in synchronized maps, tables and charts. It is naturally adapted to deal with multiscale indicators such as those used in the surveillance community, as confirmed by thi

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

2009-01-01

2

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

Microsoft Academic Search

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

Eveline Bernier; Pierre Gosselin; Thierry Badard; Yvan Bédard

2009-01-01

3

Applying Object-Oriented Conceptual Modeling Techniques to the Design of Multidimensional Databases and OLAP Applications  

Microsoft Academic Search

Few works have been presented in the area of Object-Oriented (OO) Conceptual Modeling to specify the design of multidimensional\\u000a databases (MDB) and OLAP applications. In this context, this paper describes an OO conceptual modeling approach (based on\\u000a a subset of UML) to address the peculiarities associated to this kind of systems. The structure of the system is specified\\u000a by means

Juan Carlos Trujillo; Manuel Palomar; Jaime Gómez

2000-01-01

4

Efficient Polygon Amalgamation Methods for Spatial OLAP and Spatial Data Mining  

Microsoft Academic Search

. The polygon amalgamation operation computes the boundaryof the union of a set of polygons. This is an important operationfor spatial on-line analytical processing and spatial data mining, wherepolygons representing different spatial objects often need to be amalgamatedby varying criteria when the user wants to aggregate or reclassifythese objects. The processing cost of this operation can be very highfor a

Xiaofang Zhou; David Truffet; Jiawei Han

1999-01-01

5

Updating OLAP dimensions  

Microsoft Academic Search

OLAP systems support data analysis through a multidimensional data model, according to which data facts are viewed as points in a space of application-related “dimensions” , organized into levels which conform a hierarchy. Although the usual assumption is that these points reflect the dynamic aspect of the data warehouse while dimensions are relatively static, in practice it turns out that

Carlos A. Hurtado; Alberto O. Mendelzon; Alejandro A. Vaisman

1999-01-01

6

s-OLAP: Approximate OLAP Query Evaluation on Very Large Data Warehouses via Dimensionality Reduction and Probabilistic Synopses  

Microsoft Academic Search

In this paper, we propose s-OLAP, a framework for supporting approximate range query evaluation on data cubes that meaningfully makes use of two innovative\\u000a perspectives of OLAP research, namely dimensionality reduction and probabilistic synopses. The application scenario of s-OLAP is a networked and heterogeneous very large Data Warehousing environment where applying traditional algorithms for processing\\u000a OLAP queries is too much

Alfredo Cuzzocrea

2009-01-01

7

ParaCube: A Scalable OLAP Model Based on Distributed Aggregate Computing with Sibling Cubes  

Microsoft Academic Search

The requirements of OLAP applications increase rapidly by dramatically increased data volume, users, query volume and query complexity. The requirement for shortening update period in data warehouse is another crucial factor for a scalable OLAP application. In this paper, we propose a scalable OLAP prototype to support the query processing with increasing data volume by distributing the whole fact tuples

Yansong Zhang; Shan Wang; Wei Huang

2010-01-01

8

Outstanding Challenges in OLAP  

Microsoft Academic Search

The core challenges associated with enterprise OLAP are how to structure the database and how to build a decision support architecture that allows for complex analysis and qualification. The primary components of an OLAP system-the database and the analysis engine-must be capable of handling large amounts of data in varying structures. Warehouses will continue to grow and contain data that

Jeffrey A. Bedell

1998-01-01

9

OLAP-Based Data Mining for Business Intelligence Applications in Telecommunications and E-commerce  

Microsoft Academic Search

\\u000a Business intelligence applications require the analysis and mining of large volumes of transaction data to support business\\u000a managers in making informed decisions. In a telecommunication network, hundreds of millions of call detail records are generated\\u000a daily. Business intelligence applications such as fraud detection and churn analysis require the collection and mining of\\u000a these records on a continuous basis. Similarly, electronic

Qiming Chen; Umeshwar Dayal; Meichun Hsu

2000-01-01

10

Insurance Industry Decision Support: Data Marts, OLAP and Predictive Analytics  

Microsoft Academic Search

Motivation. Data Warehouses and Data Marts increase the power and efficiency of an Insurance company's Business Intelligence capabilities by supporting queries, OLAP and data mining. Web- enabling of these applications makes them more user-friendly. The potential benefits greatly outweigh the costs. Data warehouse\\/data mart implementation streamlines information delivery for decision support and significantly simplifies development of general linear predictive models

George Bukhbinder; Michael Krumenaker; Abraham Phillips

11

OLAP Data Cube Compression Techniques: A Ten-Year-Long History  

Microsoft Academic Search

\\u000a \\u000a OnLine Analytical Processing (OLAP) is relevant for a plethora of Intelligent Data Analysis and Mining Applications and Systems, as it offers powerful tools for exploring, querying and mining massive amounts of data on the basis of fortunate and well-consolidated\\u000a multidimensional and a multi-resolution metaphors over data. Applicative settings for which OLAP plays a critical role are\\u000a manyfold, and span from

Alfredo Cuzzocrea

2010-01-01

12

Evaluation of SOVAT: An OLAP-GIS decision support system for community health assessment data analysis  

Microsoft Academic Search

BACKGROUND: Data analysis in community health assessment (CHA) involves the collection, integration, and analysis of large numerical and spatial data sets in order to identify health priorities. Geographic Information Systems (GIS) enable for management and analysis using spatial data, but have limitations in performing analysis of numerical data because of its traditional database architecture. On-Line Analytical Processing (OLAP) is a

Matthew Scotch; Bambang Parmanto; Valerie Monaco

2008-01-01

13

The Composite OLAP-Object Data Model  

SciTech Connect

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.

Pourabbas, Elaheh; Shoshani, Arie

2005-12-07

14

The Ra*-tree: An improved R-tree with Materialized Data for Supporting Range Queries on OLAP-Data  

Microsoft Academic Search

OLAP applications make use of fast indexes and materiali- zation of data. Most research treats just one topic. Either the materialized values or the design of index structures are considered. This paper examines a possible combina- tion of both techniques. The -tree is taken as an example of a multi-dimensional index structure. Aggregated data is stored in the inner nodes

Marcus Jürgens; Hans-joachim Lenz

1998-01-01

15

Spatial transformation architectures with applications: an introduction  

NASA Astrophysics Data System (ADS)

Spatial transformations (STs) constitute an important class of image operations, which include the well-known affine transformation, image rotation, scaling, warping, etc. Less well known are the anisomorphic transformations among cartographic projections such as the Mercator, gnomonic, and equal-area formats. In this preliminary study, we introduce a unifying theory of spatial transformation, expressed in terms of the Image Algebra, a rigorous, inherently parallel notation for image and signal processing. Via such theory, we can predict the implementational cost of various STs. Since spatial operations are frequently I/O-intensive, we first analyze the I/O performance of well-known architectures, in order to determine their suitability for ST implementation. Analyses are verified by simulation, with emphasis upon vision-based navigation applications. An additional applications area concerns the remapping of visual receptive fields, which facilitates visual rehabilitation in the presence of retinal damage.

Schmalz, Mark S.

1993-08-01

16

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

ERIC Educational Resources Information Center

|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…

Sharoupim, Magdy S.

2010-01-01

17

An Authorization Model for Data Warehouses and OLAP  

Microsoft Academic Search

In this paper we discuss a basic authorization model for data warehouses and OLAP offering greater expressiveness and highly increased usability with respect to security. Based on a simple formal notation we will show that access privileges can be expressed more intuitively than using SQL's grant statements.

Edgar Weippl; Oscar Mangisengi; Franz Lichtenberger

18

An overview of data warehousing and OLAP technology  

Microsoft Academic Search

Data warehousing and on-line analytical processing (OLAP) are essential elements of decision support, which has increasingly become a focus of the database industry. Many commercial products and services are now available, and all of the principal database management system vendors now have offerings in these areas. Decision support places some rather different requirements on database technology compared to traditional on-line

Surajit Chaudhuri; Umeshwar Dayal

1997-01-01

19

View discovery in OLAP databases through statistical combinatorial optimization  

SciTech Connect

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.

Hengartner, Nick W [Los Alamos National Laboratory; Burke, John [PNNL; Critchlow, Terence [PNNL; Joslyn, Cliff [PNNL; Hogan, Emilie [PNNL

2009-01-01

20

Policies for Caching OLAP Queries in Internet Proxies  

Microsoft Academic Search

The Internet now offers more than just simple information to the users. Decision makers can now issue analytical ,a s opposed to transactional, queries that involve massive data (such as, aggregations of millions of rows in a relational database) in order to identify useful trends and patterns. Such queries are often referred to as On-Line-Analytical Processing (OLAP). Typically, pages carrying

Thanasis Loukopoulos; Ishfaq Ahmad

2006-01-01

21

OLAP: A Fast, Easy, Affordable Executive Information System--Finally!  

ERIC Educational Resources Information Center

|The University of Rochester's experience with online analytical processing (OLAP), part of its executive information system, is reported. The server, a multiuser, local area network (LAN)-based database loaded from legacy systems or a data warehouse, can rapidly manipulate and display data, and allows quick creation and changing of analytical…

Stewart, Henry M.

1995-01-01

22

Spatial Analysis: Evolution, Methods, and Applications  

Microsoft Academic Search

\\u000a In a narrow sense, spatial analysis has been described as a method for analyzing spatial data, while in a broad sense it includes\\u000a revealing and clarifying processes, structures, etc., of spatial phenomena that occur on the Earth’s surface. Ultimately,\\u000a it is designed to support spatial decision-making, and to serve as a tool for assisting with regional planning and the formulation

Yuji Murayama; Rajesh B. Thapa

23

View Discovery in OLAP Databases through Statistical Combinatorial Optimization  

SciTech Connect

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.

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

2009-05-01

24

Multidimensional (OLAP) Analysis for Designing Dynamic Learning Strategy  

NASA Astrophysics Data System (ADS)

Learning strategy in an intelligent learning system is generally elaborated on the basis of assessment of the following factors: learner's time for reaction, content of the learning object, amount of learning material in a learning object, learning object specification, e-learning medium and performance control. Current work proposes architecture for dynamic learning strategy design by implementing multidimensional analysis model of learning factors. The analysis model concerns on-line analytical processing (OLAP) of learner's data structured as multidimensional cube. Main components of the architecture are analysis agent for performing the OLAP operations on learner data cube, adaptation generator and knowledge selection agent for performing adaptive navigation in the learning object repository. The output of the analysis agent is involved in dynamic elaboration of learning strategy that fits best to learners profile and behavior. As a result an adaptive learning path for individual learner and for learner groups is generated.

Rozeva, A.; Deliyska, B.

2010-10-01

25

Introducing Students to Business Intelligence: Acceptance and Perceptions of OLAP Software  

Microsoft Academic Search

This research concerns a practical on-line analytic processing (OLAP) project given to 2nd year information systems major students. They were required to analyse two sets of sales data with two different OLAP software tools, and report both on their findings and on their experiences of working with the two products. Students then completed a validated instrument with questions about each

Mike Hart; Farhan Esat; Michael Rocha; Zaid Khatieb

2007-01-01

26

Web 2.0 OLAP: From Data Cubes to Tag Clouds  

NASA Astrophysics Data System (ADS)

Increasingly, business projects are ephemeral. New Business Intelligence tools must support ad-lib data sources and quick perusal. Meanwhile, tag clouds are a popular community-driven visualization technique. Hence, we investigate tag-cloud views with support for OLAP operations such as roll-ups, slices, dices, clustering, and drill-downs. As a case study, we implemented an application where users can upload data and immediately navigate through its ad hoc dimensions. To support social networking, views can be easily shared and embedded in other Web sites. Algorithmically, our tag-cloud views are approximate range top-k queries over spontaneous data cubes. We present experimental evidence that iceberg cuboids provide adequate online approximations. We benchmark several browser-oblivious tag-cloud layout optimizations.

Aouiche, Kamel; Lemire, Daniel; Godin, Robert

27

Technological Applications to Support Children's Development of Spatial Awareness  

ERIC Educational Resources Information Center

This article presents methods and theory behind promoting children's spatial awareness through representing 3D reality in 2D cyberspace. Spatial awareness in children is an often neglected aspect in early education. However, applications such as GPS and 3D modeling programs can be used to offer children rich experiences that allow children to…

Matthews, David; Geist, Eugene A.

2002-01-01

28

Technological Applications to Support Children's Development of Spatial Awareness  

ERIC Educational Resources Information Center

|This article presents methods and theory behind promoting children's spatial awareness through representing 3D reality in 2D cyberspace. Spatial awareness in children is an often neglected aspect in early education. However, applications such as GPS and 3D modeling programs can be used to offer children rich experiences that allow children to…

Matthews, David; Geist, Eugene A.

2002-01-01

29

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

NASA Astrophysics Data System (ADS)

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.

Tsutsumi, Morito; Seya, Hajime

2009-12-01

30

Analysis of thrips distribution: application of spatial statistics and ...  

Treesearch

Title: Analysis of thrips distribution: application of spatial statistics and Kriging ... analysis of such data assumes that the counts taken over space and time are ... Our on-line publications are scanned and captured using Adobe Acrobat. During  ...

31

High spatial resolution probes for neurobiology applications  

NASA Astrophysics Data System (ADS)

Position-sensitive biological neural networks, such as the brain and the retina, require position-sensitive detection methods to identify, map and study their behavior. Traditionally, planar microelectrodes have been employed to record the cell's electrical activity with device limitations arising from the electrode's 2-D nature. Described here is the development and characterization of an array of electrically conductive micro-needles aimed at addressing the limitations of planar electrodes. The capability of this array to penetrate neural tissue improves the electrode-cell electrical interface and allows more complicated 3-D networks of neurons, such as those found in brain slices, to be studied. State-of-the-art semiconductor fabrication techniques were used to etch and passivate conformally the metal coat and fill high aspect ratio holes in silicon. These are subsequently transformed into needles with conductive tips. This process has enabled the fabrication of arrays of unprecedented dimensions: 61 hexagonally close-packed electrodes, ˜200 ?m tall with 60 ?m spacing. Electroplating the tungsten tips with platinum ensure suitable impedance values (˜600 k? at 1 kHz) for the recording of neuronal signals. Without compromising spatial resolution of the neuronal recordings, this array adds a new and exciting dimension to the study of biological neural networks.

Gunning, D. E.; Kenney, C. J.; Litke, A. M.; Mathieson, K.

2009-06-01

32

Construction and application of a spatial hurricane climatology  

NASA Astrophysics Data System (ADS)

The tracking of hurricanes, largely controlled by the organization of the presiding pressure systems, determines whether or not any given hurricane will strike a coastline. Some of the climatic influences, such as the North Atlantic Oscillation, show annual- or decadal-variability. This means that particular locations will have typical hurricane tracks that may vary with the climate. Therefore, it makes physical sense to summarize large sets of hurricane tracks by creating an average track. A hurricane climatology describes the typical hurricane to affect a location. This dissertation proposes expanding the hurricane climatology by adding a spatial dimension in the form of an average track. This is referred to as a spatial hurricane climatology. Since a hurricane track is a polyline, the construction of a spatial hurricane climatology requires averaging spatial polyline data. The technique introduced in this dissertation uses distance maps to average a set of polylines. Three applications of spatial hurricane climatologies are also detailed in this work. First they are used to construct historical hurricane chronologies. This has the possibility of providing an additional 150 years of hurricane data, providing a glimpse into hurricanes prior to the American industrial revolution. The second application is a risk analysis of local-scale hurricane winds. The technique uses statistics of past hurricanes and places them in a deterministic model. This can be performed for any coastal area, and provides wind gusts and economic loss estimations for a once-in-100-year event. Because the statistics are easy to manipulate, this allows for simple analysis of the affects of climate change. This is done as the final application of the technique. These are only a few examples of the uses of spatial hurricane climatologies, and the ideas presented in this research provide a basis for future studies on spatial hurricane patterns, as well as the analysis of spatial polyline data in general.

Scheitlin, Kelsey

33

Optically addressed spatial light modulator: performance and applications  

NASA Astrophysics Data System (ADS)

Amorphous silicon/ferroelectric liquid crystal spatial light modulator technology is reviewed. The current performance of the CUED device is summarised, together with first results from two application demonstrators in 3D and high resolution display which have been recently constructed. The paper will conclude with guidelines for improved OASLM performance in dye-doped liquid crystal layers.

Collings, Neil; Mias, Solon; Wilkinson, Timothy D.; Travis, Adrian R. L.; Moore, J. R.; Crossland, William A.

2004-01-01

34

Optically addressed spatial light modulator: performance and applications  

NASA Astrophysics Data System (ADS)

Amorphous silicon/ferroelectric liquid crystal spatial light modulator technology is reviewed. The current performance of the CUED device is summarised, together with first results from two application demonstrators in 3D and high resolution display which have been recently constructed. The paper will conclude with guidelines for improved OASLM performance in dye-doped liquid crystal layers.

Collings, Neil; Mias, Solon; Wilkinson, Timothy D.; Travis, Adrian R. L.; Moore, J. R.; Crossland, William A.

2003-12-01

35

Bayesian approaches for adaptive spatial sampling : an example application.  

SciTech Connect

BAASS (Bayesian Approaches for Adaptive Spatial Sampling) is a set of computational routines developed to support the design and deployment of spatial sampling programs for delineating contamination footprints, such as those that might result from the accidental or intentional environmental release of radionuclides. BAASS presumes the existence of real-time measurement technologies that provide information quickly enough to affect the progress of data collection. This technical memorandum describes the application of BAASS to a simple example, compares the performance of a BAASS-based program with that of a traditional gridded program, and explores the significance of several of the underlying assumptions required by BAASS. These assumptions include the range of spatial autocorrelation present, the value of prior information, the confidence level required for decision making, and ''inside-out'' versus ''outside-in'' sampling strategies. In the context of the example, adaptive sampling combined with prior information significantly reduced the number of samples required to delineate the contamination footprint.

Johnson, R. L.; LePoire, D.; Huttenga, A.; Quinn, J.

2005-05-25

36

An Experimental Evaluation of an Alternative to the Pivot Table for Ad Hoc Access to OLAP Data  

Microsoft Academic Search

This paper examines the usability of the orthodox interface to access business intelligence data held in OLAP- based systems - the pivot table. An alternative to the pivot table is described, based on Erik Thomsen's simple diagramming technique for designing OLAP data structures. That interface is compared to the pivot table in a laboratory-based experiment. The results show that the

Peter O'Donnell; Nick Draper

2004-01-01

37

A multidimensional and multiversion structure for OLAP applications  

Microsoft Academic Search

When changes occur on data organization, conventional multidimensional structures are not adapted because dimensions are supposed to be static. In many cases, especially when time covered by the data warehouse is large, dimensions of the hypercube must be redesigned in order to integrate evolutions. We propose an approach allowing to track history but also to compare data, mapped into static

Mathurin Body; Maryvonne Miquel; Yvan Bédard; Anne Tchounikine

2002-01-01

38

Hand-OLAP: A System for Delivering OLAP Services on Handheld Devices  

Microsoft Academic Search

The main drawbacks of handheld devices (small storage space, small size of the display screen, discontinuance of the connection to the WLAN, etc.) are often incompatible with the need of querying and browsing information extracted from the enormous amount of data which are accessible through the network. In this application scenario, the issues of compression and summarization of data have

Alfredo Cuzzocrea; Filippo Furfaro; Domenico Saccà

2003-01-01

39

Large capacity spatially multiplexed optical memories for incoherent correlator application  

NASA Astrophysics Data System (ADS)

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.

Yu, Francis T.

1987-05-01

40

Taming anomaly detection for industrial applications through spatial ponderation  

NASA Astrophysics Data System (ADS)

In recent years, an abundant number of applications have been developed for anomaly detection methods. Anomaly detection algorithms offer an easy and interpretable possibility to monitor the health state of virtually any technical system and industrial process that can be described by periodic measurements. But one major caveat remains: As all state-space methods, anomaly detection algorithms rely on measures of distance and these distances are distorted by any kind of irregularity in the data. The introduction of a spatial ponderation promises to cure this illness, but no mathematical foundation has been built to support this intuition. In this paper, first steps are introduced towards a stringent description of this approach.

Feller, Sebastian; Todorov, Yavor; Jaroszewski, Daniel; Chevalier, Roger

2013-10-01

41

The application of spatial analysis functions of GIS technology in urban planning  

Microsoft Academic Search

With the rapid progress of urbanization, urban planning is attracted much more attentions. The popularization of computer technology and GIS technology provides the technical support for urban planning. This paper introduces the concepts of spatial analysis functions of GIS briefly, and analyses the spatial analysis function of the application in urban planning specifically. How to apply the GIS spatial analysis

Zunying Hu; Fengxia Gu; Wenbao Liu

2010-01-01

42

An Adaptive Peer-to-Peer Network for Distributed Caching of OLAP Results  

Microsoft Academic Search

Peer-to-Peer (P2P) systems are becoming increasingly popular as they enable users to exchange digital information by participating in complex networks. Such systems are inexpensive, easy to use, highly scaleable and do not require central administration. Despite their advantages, however, limited work has been done on employing database systems on top of P2P networks. Here we propose the PeerOLAP architecture for

43

Application GIS on university planning: building a spatial database aided spatial decision  

NASA Astrophysics Data System (ADS)

With the development of university and its size enlarging, kinds of resource need to effective management urgently. Spacial database is the right tool to assist administrator's spatial decision. And it's ready for digital campus with integrating existing OMS. It's researched about the campus planning in detail firstly. Following instanced by south china agriculture university it is practiced that how to build the geographic database of the campus building and house for university administrator's spatial decision.

Miao, Lei; Wu, Xiaofang; Wang, Kun; Nong, Yu

2007-08-01

44

Spatial Objective Analysis With Applications in Atmospheric Sciences  

NASA Astrophysics Data System (ADS)

As the authors themselves remark, little review literature concerning spatial data analysis in atmospheric science has been published in the last 25 years. This book must thus be acknowledged as the only up-to-date review available. It should be of interest to meteorologists and climatologists, who are often faced with map analysis, gridpoint analysis, interpolation, spatial correlations, spatial objective analysis, analysis of vector field, or spatial stochastic models.After the first introductory chapter, the authors review, in chapter 2, the nonstatistical objective techniques based on function surfaces fitted to data arrays. These procedures involve least squares adjustment of linear or polynomial surfaces, orthogonal polynomials, Fourier harmonics, or spline surfaces. The methods are very sensitive to observation errors and erroneous model specification. Chapter 3 is concerned with empirical linear interpolation, eventually refined with a successive correction process, with an adequate definition of the weights, or with a careful examination of the frequency responses.

Guiot, J.

45

New physics and applications of Kerr spatial solitons  

NASA Astrophysics Data System (ADS)

Spatial solitons arise as a result of the interplay between diffraction and a Kerr-like nonlinearity. They are the spatial analog of the better known temporal solitons, which exist e.g. in optical fibers and result in pulse propagation without change of pulse shape. Similarly, spatial solitons are beams that do not change their shape upon propagation. In an introductory part of this work, the basic concept of spatial solitons will be reviewed and a number of properties that make them attractive for optical switching and routing devices will be described. Special emphasis will be put on the favorable properties of the AlGaAs material system in the spectral region below in the half bandgap, which were crucial for the experiments performed. One such device, a soliton steering element, has been realized and tested in AlGaAs samples. The device design and the experimental results will be presented in detail. The work performed is intended to demonstrate the basic feasibility of reconfigurable switching devices based on spatial solitons. Sufficient steering for the separation of four channels was achieved. Furthermore, one of the most interesting features of solitons is their robustness against perturbations. In birefringent media, however, the interaction between birefringence and nonlinearity leads ultimately to a polarization instability. This effect was investigated numerically and experimentally, and a radiation related polarization instability was observed for the first time. Additional work that is related to the field of Kerr spatial solitons and their generation, specifically an investigation of the linear parameters of a novel nonlinear material, the polydiacetylene p-toluene sulfonate (PTS), and the construction of a color center laser system used for the soliton experiments, are described in two appendices.

Friedrich, Lars

1999-12-01

46

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

Microsoft Academic Search

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

Andrew Lock; Francine Amon

2008-01-01

47

3D spatial interaction: applications for art, design, and science  

Microsoft Academic Search

3D interfaces use motion sensing, physical input, and spatial interaction techniques to effectively control highly dynamic virtual content. Now, with the advent of the Nintendo Wii, Sony Move, and Microsoft Kinect, game developers and researchers must create compelling interface techniques and game-play mechanics that make use of these technologies. At the same time, it is becoming increasingly clear that emerging

Joseph J. LaViola; Daniel F. Keefe

2011-01-01

48

Application of GIS to spatial analysis of mesofault populations  

Microsoft Academic Search

This paper presents a GIS approach to spatial analysis of fault populations. Coherence between fault moment tensors, a concept borrowed from the geophysical works of Kagan and Knopoff [1985a. Geophysical Journal of the Royal Astronomical Society 81(2), 429–444; 1985b. Geophysical Journal of the Royal Astronomical Society 83(3), 637–656], is the parameter used for quantifying the degree of similarity between faults.

Mauro Alberti

2005-01-01

49

Spatial noise in microdisplays for near-to-eye applications  

NASA Astrophysics Data System (ADS)

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 (?display) 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 ?display limiting performance to assist in proper imaging system specification.

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

2011-05-01

50

Spatial statistics and GIS application study in spatial variability analysis of house prices: a case study of Dongguan  

Microsoft Academic Search

According as general houses' prices data, this paper, based on spatial analysis function of Geographic information system(GIS), using semi-variogram of spatial statistics, studies spatial heterogeneity of general houses' prices distribution in Dongguan quantitatively. The results from the analysis indicate: general houses' prices have both spatial autocorrelation and sometime local spatial heterogeneity, it can be found that the spatial distribution of

Zhixiong Mei; Yangjun Ou; Weiping Hu

2009-01-01

51

Application of GIS to spatial analysis of mesofault populations  

NASA Astrophysics Data System (ADS)

This paper presents a GIS approach to spatial analysis of fault populations. Coherence between fault moment tensors, a concept borrowed from the geophysical works of Kagan and Knopoff [1985a. Geophysical Journal of the Royal Astronomical Society 81(2), 429 444; 1985b. Geophysical Journal of the Royal Astronomical Society 83(3), 637 656], is the parameter used for quantifying the degree of similarity between faults. Fault datasets from various structural sites can be imported into a GIS software such as ArcView®; using a series of customized GIS tools, data can then be checked and their spatial dependence may be investigated. This customization may be used to investigate the distribution of coherence values based on fault types (i.e. normal, left-lateral, etc.) and/or on the distance between faults. The analysis of a natural dataset reveals that, depending on the movement type, faults can display different coherence distributions with increasing distance ranges, and in some cases also a cyclic behavior. These findings can help reconstruct the history and understand the kinematic significance of fault populations.

Alberti, Mauro

2005-12-01

52

Application of Continuous Wavelet Transform in Examining Soil Spatial Variation: A Review  

Microsoft Academic Search

An adequate understanding of soil spatial variation as a function of space and scale is necessary in ecological modeling,\\u000a environmental prediction, precision agriculture, soil quality assessment and natural resources management. Soil spatial variation\\u000a can be partitioned into frequencies (scale) and positions (location) by the wavelet transform. This review focuses mainly\\u000a on different applications of the continuous wavelet transform (CWT) for

Asim Biswas; Bing Cheng Si

2011-01-01

53

SPATIAL DISCRETE-TIME EVENT HISTORY MODELS: AN APPLICATION TO HOME-LEAVING  

Microsoft Academic Search

In this paper we deal with the use of computationally complex methods in the spatial analysis of discrete-time event histories. We present an application to home-leaving data of young Italian adults. The main goal is to explore the spatially-related patterns of behaviour at a relatively fine level, by using a flexible model in conjunction with MCMC inference. We also build

Riccardo Borgoni; Francesco C. Billari

54

Toward Managing Uncertain Spatial Information for Situational Awareness Applications  

Microsoft Academic Search

Situational awareness (SA) applications monitor the real world and the entities therein to support tasks such as rapid decision making, reasoning, and analysis. Raw input about unfolding events may arrive from variety of sources in the form of sensor data, video streams, human observations, and so on, from which events of interest are extracted. Location is one of the most

Yiming Ma; Dmitri V. Kalashnikov; Sharad Mehrotra

2008-01-01

55

[Spatial resolution standardization of payload on board of remote sensing satellite based on application requirements].  

PubMed

Remote sensing application requirements are the starting point for design of payload on board earth observation satellite. The generalization, standardization and serialization of payload are the future development trend for payload design. In the present paper, based on the analysis of remote sensing application requirements, the spatial resolution standardization of satellite remote sensing payload, which is the main concerned indicator, was investigated. The design standards of national payload spatial resolution of earth observation satellite are presented, which are important to the promotion of satellite payload production and saving in design cost. PMID:22582652

Wei, Xiang-qin; Gu, Xing-fa; Yu, Tao; Meng, Qing-yan; Li, Bin; Guo, Hong

2012-03-01

56

Integrating GIS and GPS into a spatially-variable-rate herbicide application system  

NASA Astrophysics Data System (ADS)

A spatially variable rate herbicide application system was developed and a site-specific evaluation of its field performance and accuracy was conducted. The system was capable of automatically changing on-the-go the application rate of active ingredients (AI) to meet the requirements of current sprayer field location. A 4.2 ha field was sampled on an 18.3 m grid for soil texture and percent organic matter (%OM). The soil texture ranged from sandy loam to clay, while the %OM ranged from 0.98 to 2.73 percent. For the preemergence herbicide selected, a herbicide management table was used to determine the appropriate AI application rate for each area of the field depending on spatial variation of field parameter data (soil texture and %OM). For the sampled field, the AI application rate ranged from 3510 mL/ha to 5260 mL/ha. A geographical information system (GIS) software was utilized to develop a georeferenced map (management map) of field application rates. A direct nozzle injection field sprayer was equipped with a real-time differentially corrected global positioning system (DGPS). A control program was developed to retrieve the desired application rate from the GIS map utilizing position data (latitude and longitude) supplied by the DGPS system. The retrieved application rate was sent, in a voltage format, to a 21X datalogger which was used to change on-the-go the AI flow rate to correspond with the desired application rate at a specific sprayer ground speed and field position. Results revealed that the DGPS system maintained, on the average, an accuracy of one meter. However, a distance error of location determination produced by the DGPS system reached 30.84 m with a correction message age of 98 seconds. For the four application rates used in the study, the highest average application rate error (average difference between desired and calculated application rates) and CV values were 2.0 percent and 0.07 percent, respectively for the analyzed samples. The maximum application rate error was 14 percent for 96 percent of the field data points (96 percent of the time). These results showed that the control system was accurate in producing the desired application rate. On the average, the greatest reaction time of the system was 2.2 seconds. The spatial analysis showed that most application rate errors occurred near transition zones. These analysis also revealed that the contour lines of the calculated application rate maps followed the same pattern and coincide with the management map contour lines. The developed spatially variable rate herbicide application system was found to accurately reproduce the application rate management map in a repeatable fashion.

Al-Gaadi, Khalid Ali

1998-12-01

57

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

Microsoft Academic Search

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

Zhiyong Lin; Shuang Liang

2009-01-01

58

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

National Technical Information Service (NTIS)

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 lase...

D. J. Gibson F. V. Hartemann M. Y. Shverdin S. G. Anderson S. M. Betts

2007-01-01

59

Quantifying Soil Variability in GIS Applications: II Spatial Distribution of Soil Properties  

Microsoft Academic Search

Application of Geographical Information Systems (GIS) to environmental problems requires a spatial delineation of soil properties and some a priori knowledge of their variability. In the U.S.A. estimated soil properties are available from soil surveys published by the National Cooperative Soil Survey. However, information on the extent and nature of their variability is generally lacking. To remedy the situation, variability

A. S. Rogowski

1996-01-01

60

Hybrid modeling of spatial continuity for application to numerical inverse problems  

USGS Publications Warehouse

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.

Friedel, Michael J.; Iwashita, Fabio

2013-01-01

61

Spatial domain-based parallelism in large scale, participating-media, radiative transport applications  

SciTech Connect

Parallelism for gray participating media radiation heat transfer may be placed in two primary categories: spatial and angular domain-based parallelism. Angular, e.g., ray based, decomposition has received the greatest attention in the open literature for moderate sized applications where the entire geometry may be placed on processor. Angular based decomposition is limited, however, for large scale applications (O(10{sup 6}) to O(10{sup 8}) computational cells) given the memory required to store computational grids of this size on each processor. Therefore, the objective of this work is to examine the application of spatial domain-based parallelism to large scale, three-dimensional, participating-media radiation transport calculations using a massively parallel supercomputer architecture. Both scaled and fixed problem size efficiencies are presented for an application of the Discrete Ordinate method to a three dimensional, non-scattering radiative transport application with nonuniform absorptivity. The data presented shows that the spatial domain-based decomposition paradigm results in some degradation in the parallel efficiency but provides useful speedup for large computational grids.

Burns, S.P.; Christon, M.A.

1996-11-01

62

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

NASA Astrophysics Data System (ADS)

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.

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

63

Application of an optically addressed spatial light modulator to real-time speckle photography  

NASA Astrophysics Data System (ADS)

The application of a bistable, binary, amorphous silicon ferroelectric liquid crystal optically addressed spatial light modulator to speckle photography is described. The system presented has a higher space-bandwidth product than a television system and can operate at greater than 500 Hz frame rates. The output is also amenable to further optical processing. The spatial light modulator is characterised for sensitivity, contrast ratio and resolution and speckle correlation fringes from a moving object are successfully obtained. Measurement of displacements in the range 20 ?m to 70 ?m with an rms error of 3 ?m is demonstrated and the suitability of these devices to practical optical metrology is discussed.

Cunningham, D.; Sharpe, J.; Johnson, K. M.

1993-09-01

64

The application of inverse methods to spatially-distributed acoustic sources  

NASA Astrophysics Data System (ADS)

Acoustic inverse methods, based on the output of an array of microphones, can be readily applied to the characterisation of acoustic sources that can be adequately modelled as a number of discrete monopoles. However, there are many situations, particularly in the fields of vibroacoustics and aeroacoustics, where the sources are distributed continuously in space over a finite area (or volume). This paper is concerned with the practical problem of applying inverse methods to such distributed source regions via the process of spatial sampling. The problem is first tackled using computer simulations of the errors associated with the application of spatial sampling to a wide range of source distributions. It is found that the spatial sampling criterion for minimising the errors in the radiated far-field reconstructed from the discretised source distributions is strongly dependent on acoustic wavelength but is only weakly dependent on the details of the source field itself. The results of the computer simulations are verified experimentally through the application of the inverse method to the sound field radiated by a ducted fan. The un-baffled fan source with the associated flow field is modelled as a set of equivalent monopole sources positioned on the baffled duct exit along with a matrix of complimentary non-flow Green functions. Successful application of the spatial sampling criterion involves careful frequency-dependent selection of source spacing, and results in the accurate reconstruction of the radiated sound field. Discussions of the conditioning of the Green function matrix which is inverted are included and it is shown that the spatial sampling criterion may be relaxed if conditioning techniques, such as regularisation, are applied to this matrix prior to inversion.

Holland, K. R.; Nelson, P. A.

2013-10-01

65

Spatial statistics and GIS application study in spatial variability analysis of house prices: a case study of Dongguan  

NASA Astrophysics Data System (ADS)

According as general houses' prices data, this paper, based on spatial analysis function of Geographic information system(GIS), using semi-variogram of spatial statistics, studies spatial heterogeneity of general houses' prices distribution in Dongguan quantitatively. The results from the analysis indicate: general houses' prices have both spatial autocorrelation and sometime local spatial heterogeneity, it can be found that the spatial distribution of general houses' prices takes on a zonal anisotropy by anisotropic variability analysis, which means that there are different structural characteristics in different directions for general houses' prices distribution; isotropic variability analysis reveals that: the semi-variogram of general houses' prices distribution in Dongguan is best described by spherical model, changes of general houses' prices distribution are affected by both structural and random factors; the ratio of random variance (nugget) to total variance(sill) is 37.5%, therefore the spatial correlation of general houses' prices is a kind of medium correlation with Nugget/Sill being between 25% - 75%, its spatial correlation range is 16.62 kilometres; the ratio of structure variance(partial sill) to total variance is higher than the ratio of random variance to total variance, this means that certain factors' contributions to the spatial variability of houses' prices is more than random factors' contributions.

Mei, Zhixiong; Ou, Yangjun; Hu, Weiping

2009-10-01

66

RFID application to control unauthorized egress of people with spatial disorientation.  

PubMed

This article presents a "wanderer monitoring system" application based on radiofrequency identification systems, whose objective is to monitor the movement of individuals with spatial disorientation problems. The system architecture and description is shown, as well as the results of the tasks carried out. The system has been installed in 18 elderly peoples' homes belonging to the Andalusian Government (Southern Spain), and it is currently in used following more than one year of validation. PMID:17945964

Vargas, J

2006-01-01

67

The application of spatially-precise laser diagnostics to fundamental and applied combustion research  

NASA Astrophysics Data System (ADS)

Some recent contributions made by light scattering and wave mixing techniques to spatially precise laser diagnostics for thermometry and chemical composition determinations are discussed. Four diagnostic methods are addressed: Rayleigh scattering, spontaneous Raman scattering, laser-induced fluorescence spectroscopy, and coherent anti-Stokes Raman spectroscopy. The utilization of these techniques for measurements at a single point is focused on. New developments and applications of these approaches are also described.

Eckbreth, A. C.

1986-01-01

68

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

PubMed

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

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

2005-11-21

69

FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): An Ultra-Broadband Spatially Dispersed Regenerative Amplifier Free from Spatial Chirp  

NASA Astrophysics Data System (ADS)

An ultra-broadband Ti:sapphire regenerative amplifier based on spatially dispersed amplification is demonstrated experimentally Departing from previous reports, a new design of the cavity gets the amplified pulse free from spatial chirp. Utilizing this new regenerative amplifier, chirped pulses with bandwidth (FWHM) of about 80 nm are obtained, and the bandwidth is limited only by that of the incident seed pulses.

Li, Chuang; Leng, Yu-Xin; Zhang, Chun-Mei; Liang, Xiao-Yan; Li, Ru-Xin; Xu, Zhi-Zhan

2008-06-01

70

Genetic Algorithms Application for the Photoacoustic Signal Temporal Shape Analysis and Energy Density Spatial Distribution Calculation  

NASA Astrophysics Data System (ADS)

Recently, a few numerical methods based on the photoacoustic (PA) signal temporal shape analysis and energy density spatial distribution calculation, which is directly related to the laser beam spatial profile, have been presented. It has been shown that these methods allow a precise reproduction of the spatial profile and the radius of the laser beam, determining the vibrational-to-translational (V-T) relaxation time with good accuracy. Their applicability has been shown and confirmed for the analysis of an arbitrary symmetric laser beam spatial profile in cylindrical geometry. Here, the application of genetic optimization for solving the problem of a simultaneous laser beam spatial profile and V-T relaxation time determination by pulsed PAs is presented. Real-coded genetic algorithms are used to calculate the mentioned relaxation time by fitting the experimental signal {? }{p}({{r} }, t) with the theoretical one. The aim is to find combinations of PA signal parameters, namely, the radius of the laser beam and the V-T relaxation time that provide the best match with the given signal. A calculated PA signal with a known profile is used to simulate an experimental signal, and the sum of the square deviations representing deviations of the given and fitted signals is minimized by means of genetic optimization. In that way, the genetic algorithms are used to simultaneously estimate the radius of the laser beam and the V-T relaxation time efficiently and with high accuracy. Compared to previous methods, the presented method is much simpler and requires less time to compute.

Luki?, M.; ?ojbaši?, Ž.; Rabasovi?, M. D.; Markushev, D. D.; Todorovi?, D. M.

2013-10-01

71

Determining Community Health Status Priorities in an Online Analytic Processing (OLAP) Environment  

PubMed Central

Introduction: The determination of priorities is an essential component of community health status assessment. Yet, there is an acknowledged need for a systematic method which will utilize data in standardized comparisons to yield priorities based on objective analyses. Method: We have deployed a web-based system with: a flexible online analytic processing (OLAP) interface; multiple sources of event-level data conformed to common definitions in a data warehouse structure; and, centralized technical infrastructure with distributed analytical capabilities. The PRIORITIZATION TOOL integrated into the system takes full advantage of the granularity of multidimensional sources of data to: apply a series of defined objective criteria; vary the weight of those criteria and detect the reordering of the rankings in real-time; and, apply the prioritization algorithm to different categories of health status outcomes. Results: In our example, mortality outcomes for Miami-Dade County, Florida, were considered with three different weighting combinations of the four primary ranking criteria. The resultant analyses return markedly different mortality priority rankings based upon the selection and weighting of the criteria. Conclusion: Rankings of community health outcomes based on a static set of criteria with fixed weighting factors may not provide sufficient information necessary for priority setting and may, in fact, be misleading.

Studnicki, James; Fisher, John W.

2013-01-01

72

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

NASA Astrophysics Data System (ADS)

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 ?-leap spatial stochastic simulation algorithm, in terms of efficiency and accuracy, in scenarios of both molecular homogeneity and heterogeneity.

Marquez-Lago, Tatiana T.; Burrage, Kevin

2007-09-01

73

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

NASA Astrophysics Data System (ADS)

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 ?-convergence model.

Mur, Jesús; López, Fernando; Angulo, Ana

2010-09-01

74

Improved coupling to integrated spatial heterodyne spectrometers with applications to space  

NASA Astrophysics Data System (ADS)

Multiple Aperture Transform Chip Heterodyne (MATCH) spectrometers have been developed for targeted remote sensing applications in harsh environments. These waveguide-based Fourier Transform Spectrometers (FTS) offer significant improvements in resource efficiency over monolithic glass implementations, but are relatively limited in terms of input coupling efficiency and fill factor of the input facet. Integrated optics spectrometers have significant resource advantages for space applications. Monolithic Spatial Heterodyne Spectrometers are insensitive to vibration and do not require frequent calibration. In addition, Fourier Transform Spectrometers are known to provide significant performance advantages for emission spectroscopy. Ongoing work will improve the MATCH spectrometer input coupling efficiency from free space. This paper discusses the signal to noise improvements expected by incorporation of surface gratings, or back-thinning and stacking of slabs. We show that the use of surface gratings can increase the throughput over coupling to bare waveguides alone (in a single polarization), and provide close to 100% fill factor, albeit with limited field. Étendue improvements associated with stacked slabs are limited only by the sensing area available, but the fill factor of the input facet is limited to ~10%. The impact of these improvements is assessed in the context of two space-based applications: 1) Atmospheric remote sensing in the context of Spatial Heterodyne Observations of Water (solar occultation absorption spectroscopy) near 1.3 ?m and 2) Point emission spectroscopy (LIBS/Raman/fluorescence) for mineral identification on a planetary rover.

Scott, A.; Bock, P.; Ramos, C. A.; Lamontagne, B.; Cheben, P.; Florja?czyk, M.; Fernandez, I. M.; Janz, S.; Ortega-Monux, A.; Solheim, B.; Xu, D.-X.

2011-02-01

75

Microphone array signal processing with application in three-dimensional spatial hearing  

NASA Astrophysics Data System (ADS)

Microphone arrays are known to enhance the directionality and signal-to-noise ratio (SNR) over single-channel sensors. This is considered beneficial in many applications such as video-conferencing systems and hearing aids. However, this advantage comes at the price of the sensation of spatial hearing. The spatial cues due to diffractions of the head and torso are lost if the array is not fitted in the ears. In this paper we present a system that incorporates binaural hearing synthesis into array signal processing, in an attempt to recover the three-dimensional sound image that a human listener would naturally perceive. In the system, the superdirective beamformer is exploited to estimate the direction of arrival (DOA) of the incoming sound. The spatial sound image is restored by steering the beam to the direction found in the DOA session and filtering the array output with the corresponding Head Related Transfer Functions (HRTF). The algorithms have been implemented in real-time fashion using a digital signal processor. Objective and subjective experiments were performed to validate the proposed system. The experimental results showed that the accurate localization of the sound source is achievable using the array system. .

Bai, Mingsian R.; Lin, Chenpang

2005-04-01

76

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

NASA Astrophysics Data System (ADS)

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.

Lock, Andrew; Amon, Francine

2008-05-01

77

An Application of Spatial Econometrics in Relation to Hedonic House Price Modelling  

Microsoft Academic Search

This paper applies spatial econometrics in relation to hedonic house price modelling. We present and use some basic acknowledged spatial model alternatives and a battery of relevant tests. Geographically weighted regression, semiparametric analysis, and the mixed spatial Durbin model are also applied. The purpose is to detect missing spatial variables, misspecified functional form and spatial heterogeneity in estimated parameters. Such

Liv Osland

2010-01-01

78

A WebGIS system on the base of spatial data processing system for land application  

NASA Astrophysics Data System (ADS)

Traditional land management system based on PC has some shortages, such as bad openness and bad timeliness. And, it is hard to unify the criteria of data norm and database construction, easy to result in data redundancy. As a new development stage of GIS, WebGIS has perfectly solved the above-mentioned problems, so it is greatly meaningful to study digital land WebGIS. The system adopts GeoBeans6.5 as the platform which is developed by institute of remote sensing applications, CAS (Chinese Academy of Sciences). In addition, using ncgmec.jar component supplied by GeoBeans6.5, the system which is called "A WebGIS system on the base of spatial data processing system for land application" is developed under the support of IIS5.1 and java virtual machine. In the end, the main function of this system is demoed.

Wu, Dong; Wang, Qing; Wang, Huiqing; Wang, Zhijie

2009-12-01

79

Business Intelligence Applications in Retail Business: OLAP, Data Mining & Reporting Services  

Microsoft Academic Search

As a result of today's competitive business environment, companies have been trying to improve the utilization of funds effectively in their budgets for information technology investments. These companies retrieve more information with the same set of resources by means of business intelligence methods. According to Rubin (Chabrow, 2004) IT budgets are not simply declining or levelling off, rather, companies are

Ipek Deveci Kocakoç; Sabri Erdem

2010-01-01

80

Towards a typology of spatial relations and properties for urban applications  

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

81

Skew-elliptical spatial random effect modeling for areal data with application to mapping health utilization rates.  

PubMed

Mixed models incorporating spatially correlated random effects are often used for the analysis of areal data. In this setting, spatial smoothing is introduced at the second stage of a hierarchical framework, and this smoothing is often based on a latent Gaussian Markov random field. The Markov random field provides a computationally convenient framework for modeling spatial dependence; however, the Gaussian assumption underlying commonly used models can be overly restrictive in some applications. This can be a problem in the presence of outliers or discontinuities in the underlying spatial surface, and in such settings, models based on non-Gaussian spatial random effects are useful. Motivated by a study examining geographic variation in the treatment of acute coronary syndrome, we develop a robust model for smoothing small-area health service utilization rates. The model incorporates non-Gaussian spatial random effects, and we develop a formulation for skew-elliptical areal spatial models. We generalize the Gaussian conditional autoregressive model to the non-Gaussian case, allowing for asymmetric skew-elliptical marginal distributions having flexible tail behavior. The resulting new models are flexible, computationally manageable, and can be implemented in the standard Bayesian software WinBUGS. We demonstrate performance of the proposed methods and comparisons with other commonly used Gaussian and non-Gaussian spatial prior formulations through simulation and analysis in our motivating application, mapping rates of revascularization for patients diagnosed with acute coronary syndrome in Quebec, Canada. PMID:22815268

Nathoo, Farouk S; Ghosh, Pulak

2012-07-19

82

Spatial disaggregation and intensity correction of TRMM-based rainfall time series for hydrological applications in dryland catchments  

Microsoft Academic Search

A novel approach is presented for combining spatial and temporal detail from newly available TRMM-based data sets to derive hourly rainfall intensities at 1-km spatial resolution for hydrological modelling applications. Time series of rainfall intensities derived from 3-hourly 0.25° TRMM 3B42 data are merged with a 1-km gridded rainfall climatology based on TRMM 2B31 data to account for the sub-grid

E. Tarnavsky; M. Mulligan; G. Husak

2012-01-01

83

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

NASA Astrophysics Data System (ADS)

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 high resolution don't give complete indicators for follow-up and monitoring of coastal wetlands, but their combinaison, aggregation should present good technical bases to carry it out with success.

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

2003-04-01

84

Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas  

NASA Astrophysics Data System (ADS)

High resolution (?/?? ~ 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-?m 55Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10-8-10-6 times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

Hill, K. W.; Bitter, M.; Delgado-Aparacio, L.; Pablant, N. A.; Beiersdorfer, P.; Schneider, M.; Widmann, K.; Sanchez del Rio, M.; Zhang, L.

2012-10-01

85

Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas  

SciTech Connect

High resolution ({lambda}/{Delta}{lambda}{approx} 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-{mu}m {sup 55}Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10{sup -8}-10{sup -6} times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

Hill, K. W.; Bitter, M.; Delgado-Aparacio, L.; Pablant, N. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Beiersdorfer, P.; Schneider, M.; Widmann, K. [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Sanchez del Rio, M. [European Synchrotron Radiation Facility, BP 220, 38043-Grenoble Cedex (France); Zhang, L. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2012-10-15

86

Application of a field-based method to spatially varying thermal transport problems in molecular dynamics  

NASA Astrophysics Data System (ADS)

This paper derives a methodology to enable spatial and temporal control of thermally inhomogeneous molecular dynamics (MD) simulations. The primary goal is to perform non-equilibrium MD of thermal transport analogous to continuum solutions of heat flow which have complex initial and boundary conditions, moving MD beyond quasi-equilibrium simulations using periodic boundary conditions. In our paradigm, the entire spatial domain is filled with atoms and overlaid with a finite element (FE) mesh. The representation of continuous variables on this mesh allows fixed temperature and fixed heat flux boundary conditions to be applied, non-equilibrium initial conditions to be imposed and source terms to be added to the atomistic system. In effect, the FE mesh defines a large length scale over which atomic quantities can be locally averaged to derive continuous fields. Unlike coupling methods which require a surrogate model of thermal transport like Fourier's law, in this work the FE grid is only employed for its projection, averaging and interpolation properties. Inherent in this approach is the assumption that MD observables of interest, e.g. temperature, can be mapped to a continuous representation in a non-equilibrium setting. This assumption is taken advantage of to derive a single, unified set of control forces based on Gaussian isokinetic thermostats to regulate the temperature and heat flux locally in the MD. Example problems are used to illustrate potential applications. In addition to the physical results, data relevant to understanding the numerical effects of the method on these systems are also presented.

Templeton, Jeremy A.; Jones, Reese E.; Wagner, Gregory J.

2010-12-01

87

Application of Spatially Resolved High Resolution Crystal Spectrometry to ICF Plasmas  

SciTech Connect

High resolution (?/?#3;? ~ 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-?m 55 Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10-8 -10-6 times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented.

Kenneth W. Hill, et. al.

2012-09-15

88

Application of spatially resolved high resolution crystal spectrometry to inertial confinement fusion plasmas.  

PubMed

High resolution (???? ? 10 000) 1D imaging x-ray spectroscopy using a spherically bent crystal and a 2D hybrid pixel array detector is used world wide for Doppler measurements of ion-temperature and plasma flow-velocity profiles in magnetic confinement fusion plasmas. Meter sized plasmas are diagnosed with cm spatial resolution and 10 ms time resolution. This concept can also be used as a diagnostic of small sources, such as inertial confinement fusion plasmas and targets on x-ray light source beam lines, with spatial resolution of micrometers, as demonstrated by laboratory experiments using a 250-?m (55)Fe source, and by ray-tracing calculations. Throughput calculations agree with measurements, and predict detector counts in the range 10(-8)-10(-6) times source x-rays, depending on crystal reflectivity and spectrometer geometry. Results of the lab demonstrations, application of the technique to the National Ignition Facility (NIF), and predictions of performance on NIF will be presented. PMID:23126946

Hill, K W; Bitter, M; Delgado-Aparacio, L; Pablant, N A; Beiersdorfer, P; Schneider, M; Widmann, K; Sanchez del Rio, M; Zhang, L

2012-10-01

89

Ultra-Spatial Synchrotron Radiation for Imaging Molecular Chemical Structure: Applications in Plant and Animal Studies  

SciTech Connect

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 the newly developed, advanced synchrotron-based analytical technology, which can be used to reveal molecular structural-chemical features of various plant and animal tissues.

Yu,P.

2007-01-01

90

The application of geographic information systems and spatial data during Legionnaires disease outbreak responses.  

PubMed

A literature review was conducted to highlight the application and potential benefit of using geographic information systems (GIS) during Legionnaires' disease outbreak investigations. Relatively few published sources were identified, however, certain types of data were found to be important in facilitating the use of GIS, namely: patient data, locations of potential sources (e.g. cooling towers), demographic data relating to the local population and meteorological data. These data were then analysed to gain a better understanding of the spatial relationships between cases and their environment, the cases' proximity to potential outbreak sources, and the modelled dispersion of contaminated aerosols. The use of GIS in an outbreak is not a replacement for traditional outbreak investigation techniques, but it can be a valuable supplement to a response. PMID:23231895

Bull, M; Hall, I M; Leach, S; Robesyn, E

2012-12-06

91

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

PubMed Central

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 classification tasks. Conclusions: The presented spatially variant mixture model for diffusion MRI provides excellent denoising results at low signal-to-noise ratios. This makes it possible to restore data acquired with a fast (i.e., noisy) pulse sequence to acceptable noise levels. This is the case in diffusion MRI, where a large number of diffusion-weighted volumes have to be acquired under clinical time constraints.

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

2011-01-01

92

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

Microsoft Academic Search

This study applies a hedonic model to assess the economic benefits of air quality improvement following the 1990 Clean Air\\u000a Act Amendment at the county level in the lower 48 United States. An instrumental variable approach that combines geographically\\u000a weighted regression and spatial autoregression methods (GWR-SEM) is adopted to simultaneously account for spatial heterogeneity\\u000a and spatial autocorrelation. SEM mitigates spatial

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

2010-01-01

93

Application of a spatial decision support system in managing the protection forests of Vienna for sustained yield of water resources  

Microsoft Academic Search

The development and application of a spatial decision support system (SDSS) for silvicultural planning in forests managed for sustained yield of water resources is presented. The implementation of core components of the SDSS is described. As an example, the development of a decision model for selecting the best silvicultural treatment option for stands scheduled for natural regeneration is discussed. The

Harald Vacik; Manfred J. Lexer

2001-01-01

94

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...

95

Optimization and application of median filter corrections to relieve diverse spatial patterns in microtiter plate data.  

PubMed

The standard (STD) 5 × 5 hybrid median filter (HMF) was previously described as a nonparametric local backestimator of spatially arrayed microtiter plate (MTP) data. As such, the HMF is a useful tool for mitigating global and sporadic systematic error in MTP data arrays. Presented here is the first known HMF correction of a primary screen suffering from systematic error best described as gradient vectors. Application of the STD 5 × 5 HMF to the primary screen raw data reduced background signal deviation, thereby improving the assay dynamic range and hit confirmation rate. While this HMF can correct gradient vectors, it does not properly correct periodic patterns that may present in other screening campaigns. To address this issue, 1 × 7 median and a row/column 5 × 5 hybrid median filter kernels (1 × 7 MF and RC 5 × 5 HMF) were designed ad hoc, to better fit periodic error patterns. The correction data show periodic error in simulated MTP data arrays is reduced by these alternative filter designs and that multiple corrective filters can be combined in serial operations for progressive reduction of complex error patterns in a MTP data array. PMID:21900202

Bushway, Paul J; Azimi, Behrad; Heynen-Genel, Susanne

2011-09-06

96

Spatial modeling of survival and residency and application to the Monitoring Avian Productivity and Survivorship program  

Microsoft Academic Search

Broad-scale bird-ringing programs are a core component of national and international avian monitoring and research efforts.\\u000a Despite rich spatial structure in data from these programs, little attention has been paid to spatial modeling of demographic\\u000a rates. Here we implemented a Bayesian analysis of a hierarchical capture–recapture model to provide spatially explicit (2°\\u000a blocks) and year-specific estimates of adult apparent survival

James F. SaraccoJ; J. Andrew Royle; David F. DeSante; Beth Gardner

97

A method for spatial–temporal forecasting with an application to real estate prices  

Microsoft Academic Search

Using 5243 housing price observations during 1984–92 from Baton Rouge, this manuscript demonstrates the substantial benefits obtained by modeling the spatial as well as the temporal dependence of the errors. Specifically, the spatial–temporal autoregression with 14 variables produced 46.9% less SSE than a 12-variable regression using simple indicator variables for time. More impressively, the spatial–temporal regression with 14 variables displayed

R. Kelley Pace; Ronald Barry; Otis W. Gilley; C. F. Sirmans

2000-01-01

98

APPLICATION OF SPATIAL INTERPOLATION OF METEOROLOGICAL DATA TO APPLE RIPENING MODEL  

Microsoft Academic Search

Aiming at an estimation of harvest time and an evaluation of fruit quality of a Golden Delicious apple cultivar, a spatial interpolation of temperature and solar radiation has been performed, searching for temporal and spatial relations among meteorological data and chemical- physical parameters, in GRASS frame. The study as been carried out using meteorological data obtained from 12 stations in

Marco COLOMBO; Marco CIAMPA

99

Spatially distributed assessment of solar resources for energy applications in Slovakia  

Microsoft Academic Search

Spatial and temporal distribution of available solar energy depends on several factors. Besides latitude and astronomical factors it is strongly influenced by climate factors (e.g. cloudiness, turbidity) and topography. This paper presents a solar database of Slovakia containing spatially-distributed solar energy resource data necessary for planning, sitting and forecasting of solar device installations. The database consists of several data sets

Jaroslav HOFIERKA

2008-01-01

100

Mapping Spatial Attributes in Survey Research for Natural Resource Management: Methods and Applications  

Microsoft Academic Search

Traditional survey research measures attributes such as opinions, attitudes, beliefs, values, norms, and preferences. Few public surveys have attempted to map perceived spatial attributes of places and landscapes, a subject of increasing importance to environmental and natural resource management. For the past 5 years, this researcher has included spatial measures of landscape values and attributes in five separate surveys of

Gregory Brown

2004-01-01

101

Application of GIS to analyze the spatial-temporal service gap for Hsinchu City bus system  

Microsoft Academic Search

With the vision of sustainable transportation development, government authorities in Taiwan have been aggressively developing seamless environment for public transportation services in the hopes of satisfying the general users need for spatial as well as temporal seamless transportation services. The main objective of this study was to develop indexes capable of assessing the spatial-temporal service gaps of Hsinchu City bus

Jau-Ming Su; Cheng-Chen Kou; Mei-Hui Shen; Wen-Chi Ho; Chih-Hung Chang

2011-01-01

102

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

PubMed

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

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

2012-05-16

103

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

PubMed

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

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

2009-09-29

104

Application Of New Spatial Statistical Stream Models For Precise Downscaling Of Climate Change Effects On Temperatures In River Networks  

NASA Astrophysics Data System (ADS)

A warming climate will bring unprecedented changes to stream and river ecosystems, with temperature considerations being of utmost importance, given that most aquatic organisms are ectothermic. Previous broad-scale assessments of climate impacts to streams have been limited by inadequate availability of stream temperature data and often relied on surrogate relationships between air temperature and elevation that are often imprecise. Mechanistic models have sometimes been used to model stream thermal responses directly, but intensive parameterization limits the spatial scope of these applications. Modeling approaches are needed that address stream temperatures directly at the larger spatial scales commensurate with most conservation and restoration planning efforts. We applied new spatial statistical models that account for network topology (i.e., flow direction and volume) to an extensive, but non-random stream temperature database (n = 780) compiled across a 13 year period (1993-2006) for a large (2,500 km) mountain river network in central Idaho. Four predictors—radiation, elevation, air temperature, and stream flow—were used in the spatial model to represent important geomorphic and climatic effects on mean summer stream temperatures. The spatial models accounted for autocorrelation among sample sites to provide improved parameter estimates and predictive accuracy (R2 = 0.93; RMSPE = 0.74?C) relative to traditional, non-spatial models (R2 = 0.68; RMSPE = 1.53?C). A small bias between observed stream temperatures and those predicted by the spatial models amounted to 0.5?C at the extremes of the observed temperature range (5?C - 20?C) and caused over- (under-) predictions for the coldest (warmest) streams. This bias could have arisen from elevational gradients associated with influxes of cold, snowmelt groundwater or alterations in valley form due to past glacial activity. Better understanding regarding the importance of these and other factors that effect local variability in stream warming rates is needed to optimize future downscaling efforts. However, the application of spatial models for streams provides a significant advance in our ability to translate climate change impacts to aquatic ecosystems. Moreover, the approach is widely applicable given the advent of GIS capabilities, increasing availability of stream temperature sensor networks, and flexibility to accommodate climatic forcing data from a variety of sources.

Isaak, D.; Luce, C.; Peterson, E.

2009-12-01

105

Mixture models with adaptive spatial regularization for segmentation with an application to FMRI data.  

PubMed

Mixture models are often used in the statistical segmentation of medical images. For example, they can be used for the segmentation of structural images into different matter types or of functional statistical parametric maps (SPMs) into activations and nonactivations. Nonspatial mixture models segment using models of just the histogram of intensity values. Spatial mixture models have also been developed which augment this histogram information with spatial regularization using Markov random fields. However, these techniques have control parameters, such as the strength of spatial regularization, which need to be tuned heuristically to particular datasets. We present a novel spatial mixture model within a fully Bayesian framework with the ability to perform fully adaptive spatial regularization using Markov random fields. This means that the amount of spatial regularization does not have to be tuned heuristically but is adaptively determined from the data. We examine the behavior of this model when applied to artificial data with different spatial characteristics, and to functional magnetic resonance imaging SPMs. PMID:15638182

Woolrich, Mark W; Behrens, Timothy E J; Beckmann, Christian F; Smith, Stephen M

2005-01-01

106

The Application of a Simple Spatial Multi-Criteria Analysis Shell to Natural Resource Management Decision Making  

Microsoft Academic Search

\\u000a Natural resource management decision making generally requires the analysis of a variety of environmental, social and economic\\u000a information, incorporating value judgement and policy and management goals. Justifiable decisions depend on the logical and\\u000a transparent combination and analysis of information. This chapter describes the application of spatial multi-criteria analysis\\u000a to natural resource assessment and priority setting at regional and national scales

Robert G Lesslie; Michael J Hill; Patricia Hill; Hamish P Cresswell; Steve Dawson

107

A Preliminary Study of Two-Handed Manipulation for Spatial Input Tasks in a 3D Modeling Application  

Microsoft Academic Search

\\u000a We developed a free form deformation application for an immersive environment in which users can interact freely using data\\u000a gloves. To ensure better comfort and performances, we added the possibility of bimanual interaction in our environment. To\\u000a investigate the actual gain obtained by this interaction technique, we designed an experimental protocol based on spatial\\u000a input tasks. In our experiment, we

Antonio Capobianco; Manuel Veit; Dominique Bechmann

108

Bayesian Parametric Accelerated Failure Time Spatial Model and its Application to Prostate Cancer  

PubMed Central

Prostate cancer is the most common cancer diagnosed in American men and the second leading cause of death from malignancies. There are large geographical variation and racial disparities existing in the survival rate of prostate cancer. Much work on the spatial survival model is based on the proportional hazards model, but few focused on the accelerated failure time model. In this paper, we investigate the prostate cancer data of Louisiana from the SEER program and the violation of the proportional hazards assumption suggests the spatial survival model based on the accelerated failure time model is more appropriate for this data set. To account for the possible extra-variation, we consider spatially-referenced independent or dependent spatial structures. The deviance information criterion (DIC) is used to select a best fitting model within the Bayesian frame work. The results from our study indicate that age, race, stage and geographical distribution are significant in evaluating prostate cancer survival.

Zhang, Jiajia; Lawson, Andrew B.

2010-01-01

109

A Cokriging Method for Spatial Functional Data with Applications in Oceanology  

Microsoft Academic Search

We propose a method based on a functional linear model which takes into account the spatial dependencies between sampled functions.\\u000a The problem of estimating a function when spatial samples are available is turned to a standard cokriging problem for suitable\\u000a choices of the regression function. This work is illustrated with environmental data in Antarctic where marine mammals operate\\u000a as samplers.

Pascal Monestiez; David Nerini

110

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

PubMed

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. PMID:22543611

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

2012-03-01

111

Spatial segregation in stage-structured populations with an application to Tribolium  

Microsoft Academic Search

Spatial segregation among life-cycle stages has been observed in many stage-structured species, including species of the flour beetle Tribolium. We investigate density-dependent dispersal of life-cycle stages as a possible mechanism responsible for this separation. We explore this hypothesis using stage-structured, integrodifference equation (IDE) models that incorporate density-dependent dispersal kernels. We first investigate mechanisms that can lead to spatial patterns in

Suzanne L. Robertson; J. M. Cushing

2011-01-01

112

Integration of Geographic Information into Multidimensional Models  

Microsoft Academic Search

Data warehousing and On Line Analytical Processing (OLAP) are technologies intended to support business intelligence. Spatial\\u000a OLAP integrates spatial data into OLAP systems. Spatial OLAP models reformulate main OLAP concepts to define spatial dimensions\\u000a and measures, and spatio-multidimensional navigation operators. Spatial OLAP reduces geographic information to its spatial\\u000a component without taking into account map generalization relationships into the multidimensional decision

Sandro Bimonte; Anne Tchounikine; Michela Bertolotto

2008-01-01

113

Application of GIS for the modeling of spatial distribution of air pollutants in Tehran  

NASA Astrophysics Data System (ADS)

Spatial modeling of air pollutants in the mega cities such as Tehran is a useful method for the estimation of pollutants in the non-observed positions in Tehran. In addition, spatial modeling can determine the level of pollutants in different regions of Tehran. There are some typical interpolation techniques (e.g., Inverse Distance Weighting (IDW), Thin Plate Splines (TPS), Kriging and Cokriging) for spatial modeling of air pollutants. In this study, different interpolation methods are compared for spatial modeling of carbon monoxide in Tehran. The three-hourly data of wind speed and direction was received from 5 meteorological stations in Tehran. The hourly data of carbon monoxide in 2008 have been extracted of 16 air pollution monitoring stations in Tehran. The hourly data of 3 selected days in 2008 (72 hours) and similarly, the daily data of 36 days in 2008 (3 days in each month) were utilized for spatial modeling in this study. Different typical interpolation techniques were implemented on different hourly and daily data using ArcGIS. The percent of absolute error of each interpolation techniques for each hourly and daily interpolated data was calculated using cross validation techniques. Results demonstrated that Cokriging has better performance than other typical interpolation techniques in the hourly and daily modeling of carbon monoxide. Because it utilizes three input variables (Latitude, Longitude and altitude) data for spatial modeling but the other methods use only two input variables (Latitude and Longitude). In addition, the wind speed and direction maps were compatible with the results of spatial modeling of carbon monoxide. Kriging was the appropriate method after Cokriging.

Sargazi, Saeed; Taheri Shahraiyni, Hamid; Habibi-Nokhandan, Majid; Sanaeifar, Melika

2011-10-01

114

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

SciTech Connect

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.

Marks, D.; Turner, D.P. [Environmental Research Lab., Corvallis, OR (United States)

1995-06-01

115

Spatially-Variant Morpho-Hessian Filter: Efficient Implementation and Application  

NASA Astrophysics Data System (ADS)

Elongated objects are more difficult to filter than more isotropic ones because they locally comprise fewer pixels. For thin linear objects, this problem is compounded because there is only a restricted set of directions that can be used for filtering, and finding this local direction is not a simple problem. In addition, disconnections can easily appear due to noise. In this paper we tackle both issues by combining a linear filter for direction finding and a morphological one for filtering. More specifically, we use the eigen-analysis of the Hessian for detecting thin, linear objects, and a spatially-variant opening or closing for their enhancement and reconnection. We discuss the theory of spatially-variant morphological filters and present an efficient algorithm. The resulting spatially-variant morphological filter is shown to successfully enhance directions in 2D and 3D examples illustrated with a brain blood vessel segmentation problem.

Tankyevych, Olena; Talbot, Hugues; Dokladál, Petr; Passat, Nicolas

116

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

NASA Astrophysics Data System (ADS)

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.

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

2007-11-01

117

An application of spatial decision tree for classification of air pollution index  

Microsoft Academic Search

A decision tree is an analysis skill and a classification algorithm, whose basic principle is the combination of probability theory and an analysis tool of tree shapes. It derives a hierarchy of partition rules with respect to a target attribute of a large dataset. Nowadays, concrete coordinates exist in lots of datasets, which leads to the spatial distribution of datasets.

Minyue Zhao; Xiang Li

2011-01-01

118

Spatial targeting using queries in a 3-D GIS environment with application to mineral exploration  

Microsoft Academic Search

A query framework for spatial targeting within a 3-D geographic information system (GIS) software environment is introduced. Input to a query consists of parameters relevant to the query type together with a set of Common Earth Modelling objects represented as point sets, polygonal lines, surfaces, and grids or a region set (subset) thereof. The result of a 3-D GIS query

Kevin Sprague; Eric de Kemp; Winston Wong; John McGaughey; Gervais Perron; Tucker Barrie

2006-01-01

119

Spatial Gaussian Filtering of Bayer Images with Applications to Color Segmentation  

Microsoft Academic Search

A single sensor color imaging device has a color filter array (CFA) laid on top of its photodiodes, which spatially samples bandpassed spectral responses. Hence, with the popular Bayer pattern, at every pixel site either red, green or blue light is measured. A process known as demosaicing interpolates the vector-valued color image from the scalar-valued sensor output, termed here as

Johannes Herwig; Josef Pauli

120

Applications of geographical information systems (GIS) for spatial decision support in aquaculture  

Microsoft Academic Search

Geographical information systems (GIS) are becoming an increasingly integral component of natural resource management activities worldwide. However, despite some indication that these tools are receiving attention within the aquaculture community, their deployment for spatial decision support in this domain continues to be very slow. This situation is attributable to a number of constraints including a lack of appreciation of the

Shree S. Nath; John P. Bolte; Lindsay G. Ross; Jose Aguilar-Manjarrez

2000-01-01

121

A new metric based on extended spatial frequency and its application to DWT based fusion algorithms  

Microsoft Academic Search

A new quantitative metric is proposed to objectively evaluate the quality of fused imagery. The measured value of the proposed metric is used as feedback to a fusion algorithm such that the image quality of the fused image can potentially be improved. This new metric, called the ratio of spatial frequency error {(rSFe)}, is derived from the definition of a

Yufeng Zheng; Edward A. Essock; Bruce C. Hansen; Andrew M. Haun

2007-01-01

122

Bayesian parametric accelerated failure time spatial model and its application to prostate cancer  

Microsoft Academic Search

Prostate cancer (PrCA) is the most common cancer diagnosed in American men and the second leading cause of death from malignancies. There are large geographical variation and racial disparities existing in the survival rate of PrCA. Much work on the spatial survival model is based on the proportional hazards (PH) model, but few focused on the accelerated failure time (AFT)

Jiajia Zhang; Andrew B. Lawson

2011-01-01

123

Analysis of nonintrinsic spatial variability by residual kriging with application to regional groundwater levels  

Microsoft Academic Search

A method for obtaining pointwise or spatially averaged estimates of a nonintrinsic function is introduced based on residual kriging. The method relies on a stepwise iterative regression process for simultaneously estimating the global drift and residual semivariogram. Estimates of the function are then obtained by solving a modified set of simple kriging equations written for the residuals. The modification consists

Shlomo P. Neuman; Elizabeth A. Jacobson

1984-01-01

124

FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Spatial Soliton Solutions in a Harmonic Potential  

NASA Astrophysics Data System (ADS)

The F-expansion technique and the homogeneous nonlinear balance principle have been applied for solving a general (1+1)-dimensional nonlinear Schrödinger equation (NLSE) with varying coefficients and a harmonic potential. A family of (1+1)D spatial solitons has been obtained. The evolution features of exact solutions have been investigated.

Xu, Si-Liu; Liang, Jian-Chu; Yi, Lin

2009-07-01

125

Application of Bayesian spatial statistical methods to analysis of haplotypes effects and gene mapping  

Microsoft Academic Search

We propose a method to analyze haplotype effects using ideas derived from Bayesian spatial statistics. We assume that two haplotypes that are similar to one another in structure are likely to have similar risks, and define a distance metric to specify the appropriate level of closeness between the two haplotypes. Through the choice of distance metric, varying levels of population

John Molitor; Paul Marjoram; Duncan Thomas

2003-01-01

126

SpPack: spatial point pattern analysis in Excel using Visual Basic for Applications (VBA)  

Microsoft Academic Search

Many different sciences have developed many different tests to describe and characterise spatial point data. For example, all the trees in a given area may be mapped such that their x, y co-ordinates and other variables, or ‘marks’, (e.g. species, size) might be recorded. Statistical techniques can be used to explore interactions between events at different length scales and interactions

George L. W. Perry

2004-01-01

127

Application of Spatial Bandwidth Concepts to MAS Pole Location for Dielectric Cylinders  

Microsoft Academic Search

The concept of effective spatial bandwidth (EBW) is extended from the case of an MAS solution for perfectly conducting (PEC) cylinders to dielectric cylinders. It is shown that the ideas and results for the con- ducting cylinder apply in a straightforward manner to the dielectric case. For the dielectric case, there are two auxiliary surfaces. Because the EBW calculations are

James E. Richie

2011-01-01

128

Frequency stabilization, tuning, and spatial mode control of terahertz quantum cascade lasers for coherent transceiver applications  

Microsoft Academic Search

THz quantum cascade lasers (TQCLs) first demonstrated in 2002 are a promising source of THz coherent radiation for use as both transmitters and local oscillators in coherent heterodyne detection systems. However, present TQCLs have deficiencies which include lack of frequency tunability, as well as inadequate spatial and temporal coherence. In this thesis we have addressed these issues to demonstrate an

Andriy Danylov

2010-01-01

129

Techniques for the spatial downscaling of rain for application in SHF propagation modelling  

Microsoft Academic Search

There is current interest in the use of numerical weather prediction (NWP) models for propagation modelling for radio system design. However, NWP models currently operate with spatial and temporal resolutions much lower than those ideally required for modelling on typical terrestrial and satellite fixed links. There are fundamental problems when predicting the behaviour of links, possibly only a few hundred

Duncan D. Hodges; Robert J. Watson; K. S. Paulson

2005-01-01

130

Full Spin and Spatial Symmetry Adapted Technique for Correlated Electronic Hamiltonians: Application to an Icosahedral Cluster  

Microsoft Academic Search

One of the long standing problems in quantum chemistry had been the inability to exploit full spatial and spin symmetry of an electronic Hamiltonian belonging to a non-Abelian point group. Here we present a general technique which can utilize all the symmetries of an electronic (magnetic) Hamiltonian to obtain its full eigenvalue spectrum. This is a hybrid method based on

Shaon Sahoo; S. Ramasesha

2010-01-01

131

Linear spatial interpolation: Analysis with an application to San Joaquin Valley  

Microsoft Academic Search

The properties of linear spatial interpolators of single realizations and trend components of regionalized variables are examined in this work. In the case of the single realization estimator explicit and exact expressions for the weighting vector and the variances of estimator and estimation error were obtained from a closed-form expression for the inverse of the Lagrangian matrix. The properties of

H. A. Loaiciga; R. H. Shumway; W. W.-G. Yeh

1988-01-01

132

Multidimensional Access Methods: Important Factor for Current and Next Decade's Applications in Spatial Databases  

Microsoft Academic Search

In spatial databases search operations take an important role. These operations consist of the point query (find all objects that contain a given search point), the range query (find all objects that overlap a given search range) (GAE98) and the nearest neighbor query (find k objects (k >= 1) that are closest to a given object). They are very costly

Dang Tran KHANH; Josef KÜNG; Roland WAGNER

133

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

PubMed

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

Brakebill, Jw; Wolock, Dm; Terziotti, Se

2011-10-01

134

A spatial structural equation model with an application to area health needs  

Microsoft Academic Search

Indices of population ‘health need’ are often used to distribute health resources or assess equity in service provision. This article describes a spatial structural equation model incorporating multiple indicators of need and multiple population health risks that affect need (analogous to multiple indicators–multiple causes models). More specifically, the multiple indicator component of the model involves health outcomes such as hospital

Peter Congdon

2010-01-01

135

Mixture models with adaptive spatial regularization for segmentation with an application to FMRI data  

Microsoft Academic Search

Mixture models are often used in the statistical segmentation of medical images. For example, they can be used for the segmentation of structural images into different matter types or of functional statistical parametric maps (SPMs) into activations and nonactivations. Nonspatial mixture models segment using models of just the histogram of intensity values. Spatial mixture models have also been developed which

Mark W. Woolrich; Timothy E. J. Behrens; Christian F. Beckmann; Stephen M. Smith

2005-01-01

136

Mixture models with adaptive spatial regularization for segmentation with an application to FMRI data  

Microsoft Academic Search

Mixture models are often used in the statistical seg- mentation of medical images. For example, they can be used for the segmentation of structural images into different matter types or of functional statistical parametric maps (SPMs) into activations and nonactivations. Nonspatial mixture models segment using models of just the histogram of intensity values. Spatial mixture models have also been developed

Mark William Woolrich; Timothy Edward John Behrens; Christian F. Beckmann; Stephen M. Smith

2005-01-01

137

An integrative hierarchical stepwise sampling strategy for spatial sampling and its application in digital soil mapping  

Microsoft Academic Search

Sampling design plays an important role in spatial modeling. Existing methods often require a large amount of samples to achieve desired mapping accuracy, but imply considerable cost. When there are not enough resources for collecting a large set of samples at once, stepwise sampling approach is often the only option for collecting the needed large sample set, especially in the

Lin Yang; A-Xing Zhu; Feng Qi; Cheng-Zhi Qin; Baolin Li; Tao Pei

2012-01-01

138

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

Microsoft Academic Search

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

Lijuan Zhou; Minhua Wu; Shuang Li

2009-01-01

139

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

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

140

Automated Spatial-Semantic Modeling with Applications to Place Labeling and Informed Search  

Microsoft Academic Search

This paper presents a spatial-semantic modeling sys- tem featuring automated learning of object-place rela- tions from an online annotated database, and the ap- plication of these relations to a variety of real-world tasks. The system is able to label novel scenes with place information, as we demonstrate on test scenes drawn from the same source as our training set. We

Pooja Viswanathan; David Meger; Tristram Southey; James J. Little; Alan K. Mackworth

2009-01-01

141

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

Microsoft Academic Search

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

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

2006-01-01

142

Application and evaluation of a measured spatially variant system model for PET image reconstruction.  

PubMed

Accurate system modeling in tomographic image reconstruction has been shown to reduce the spatial variance of resolution and improve quantitative accuracy. System modeling can be improved through analytic calculations, Monte Carlo simulations, and physical measurements. The purpose of this work is to improve clinical fully-3-D reconstruction without substantially increasing computation time. We present a practical method for measuring the detector blurring component of a whole-body positron emission tomography (PET) system to form an approximate system model for use with fully-3-D reconstruction. We employ Monte Carlo simulations to show that a non-collimated point source is acceptable for modeling the radial blurring present in a PET tomograph and we justify the use of a Na22 point source for collecting these measurements. We measure the system response on a whole-body scanner, simplify it to a 2-D function, and incorporate a parameterized version of this response into a modified fully-3-D OSEM algorithm. Empirical testing of the signal versus noise benefits reveal roughly a 15% improvement in spatial resolution and 10% improvement in contrast at matched image noise levels. Convergence analysis demonstrates improved resolution and contrast versus noise properties can be achieved with the proposed method with similar computation time as the conventional approach. Comparison of the measured spatially variant and invariant reconstruction revealed similar performance with conventional image metrics. Edge artifacts, which are a common artifact of resolution-modeled reconstruction methods, were less apparent in the spatially variant method than in the invariant method. With the proposed and other resolution-modeled reconstruction methods, edge artifacts need to be studied in more detail to determine the optimal tradeoff of resolution/contrast enhancement and edge fidelity. PMID:20199927

Alessio, Adam M; Stearns, Charles W; Tong, Shan; Ross, Steven G; Kohlmyer, Steve; Ganin, Alex; Kinahan, Paul E

2010-03-01

143

The ArcView\\/XGobi\\/XploRe Environment: Technical Details and Applications for Spatial Data Analysis  

Microsoft Academic Search

:This article describes the dynamic linking of threesoftware packages to allow spatial data analysiswithin one single software environment. The workpresented here is an extension into a third directionof an existing link: The statistical computingenvironment XploRe has been added to the bidirectionallink between the Geographic InformationSystem (GIS) ArcView 3.0TMand the dynamic statisticalgraphics (DSG) program XGobi. This articlepresents information about the technical...

Jurgen Symanzik; S. Klinke; S. Schmelzer; D. Cook

1997-01-01

144

Frailty modeling for spatially correlated survival data, with application to infant mortality in Minnesota.  

PubMed

The use of survival models involving a random effect or 'frailty' term is becoming more common. Usually the random effects are assumed to represent different clusters, and clusters are assumed to be independent. In this paper, we consider random effects corresponding to clusters that are spatially arranged, such as clinical sites or geographical regions. That is, we might suspect that random effects corresponding to strata in closer proximity to each other might also be similar in magnitude. Such spatial arrangement of the strata can be modeled in several ways, but we group these ways into two general settings: geostatistical approaches, where we use the exact geographic locations (e.g. latitude and longitude) of the strata, and lattice approaches, where we use only the positions of the strata relative to each other (e.g. which counties neighbor which others). We compare our approaches in the context of a dataset on infant mortality in Minnesota counties between 1992 and 1996. Our main substantive goal here is to explain the pattern of infant mortality using important covariates (sex, race, birth weight, age of mother, etc.) while accounting for possible (spatially correlated) differences in hazard among the counties. We use the GIS ArcView to map resulting fitted hazard rates, to help search for possible lingering spatial correlation. The DIC criterion (Spiegelhalter et al., Journal of the Royal Statistical Society, Series B 2002, to appear) is used to choose among various competing models. We investigate the quality of fit of our chosen model, and compare its results when used to investigate neonatal versus post-neonatal mortality. We also compare use of our time-to-event outcome survival model with the simpler dichotomous outcome logistic model. Finally, we summarize our findings and suggest directions for future research. PMID:12925334

Banerjee, Sudipto; Wall, Melanie M; Carlin, Bradley P

2003-01-01

145

Spatial CDF Estimation and Visualization with Applications to Forest Health Monitoring  

Microsoft Academic Search

. This paper discusses the estimation and visualizationof spatial cumulative distribution functions (CDFs)with extensions to bivariate and higher dimensional CDFs.The use of CDFs is an important part of the USEPA EnvironmentalMonitoring and Assessment Program's (EMAP)work in assessing and monitoring the state of the nation'senvironmental resources. The resources in a given region canbe classified broadly into nominal, marginal, or sub-nominalstates. These

James J. Majure; Dianne Cook; Noel Cressie; Mark Kaiser; Soumendra Lahiri; Jürgen Symanzik

1995-01-01

146

Investigation of spatial coupling aspects for coupled code application in PWR safety analysis  

Microsoft Academic Search

The simulation of nuclear power plant accident conditions requires three-dimensional (3-D) modeling of the reactor core to ensure a realistic description of physical phenomena. This paper describes a part of the research activities carried out on the sensitivity of coupled neutronics\\/thermal-hydraulic system code's results to the spatial mesh overlays used for modeling pressurized water reactor (PWR) cores for analysis of

Nadejda K Todorova; Kostadin N Ivanov

2003-01-01

147

Application and Evaluation of a Measured Spatially Variant System Model for PET Image Reconstruction  

PubMed Central

Accurate system modeling in tomographic image reconstruction has been shown to reduce the spatial variance of resolution and improve quantitative accuracy. System modeling can be improved through analytic calculations, Monte Carlo simulations, and physical measurements. The purpose of this work is to improve clinical fully-3-D reconstruction without substantially increasing computation time. We present a practical method for measuring the detector blurring component of a whole-body positron emission tomography (PET) system to form an approximate system model for use with fully-3-D reconstruction. We employ Monte Carlo simulations to show that a non-collimated point source is acceptable for modeling the radial blurring present in a PET tomograph and we justify the use of a Na22 point source for collecting these measurements. We measure the system response on a whole-body scanner, simplify it to a 2-D function, and incorporate a parameterized version of this response into a modified fully-3-D OSEM algorithm. Empirical testing of the signal versus noise benefits reveal roughly a 15% improvement in spatial resolution and 10% improvement in contrast at matched image noise levels. Convergence analysis demonstrates improved resolution and contrast versus noise properties can be achieved with the proposed method with similar computation time as the conventional approach. Comparison of the measured spatially variant and invariant reconstruction revealed similar performance with conventional image metrics. Edge artifacts, which are a common artifact of resolution-modeled reconstruction methods, were less apparent in the spatially variant method than in the invariant method. With the proposed and other resolution-modeled reconstruction methods, edge artifacts need to be studied in more detail to determine the optimal tradeoff of resolution/contrast enhancement and edge fidelity.

Stearns, Charles W.; Tong, Shan; Ross, Steven G.; Kohlmyer, Steve; Ganin, Alex; Kinahan, Paul E.

2010-01-01

148

An Application Based on Spatial-Relationship to Basketball Defensive Strategies  

Microsoft Academic Search

\\u000a This paper aims to develop a simulated system used for teaching and training basketball defensive strategies.  Respectively,\\u000a defensive strategies can be described within one method by editing video recorded from basketball games into desired clips\\u000a for analysis and storing them into the database. In this paper, we used Spatial-Temporal Relationships to describe the local\\u000a defensive movements by the basketball players

Su-li Chin; Chun-hong Huang; Chia-tong Tang; Jason C. Hung

2005-01-01

149

Investigating spatial climate relations using CARTs: An application to persistent hot days in a multimodel ensemble  

NASA Astrophysics Data System (ADS)

This study introduces Classification and Regression Trees (CARTs) as a new tool to explore spatial relationships between different climate patterns in a multimodel ensemble. We demonstrate the potential of CARTs by a simple case study based on time-aggregated patterns of circulation (represented by average levels and variabilities of sea level pressure, SLP) and land surface conditions (diagnosed from the time-averaged surface water balance) from regional climate model simulations (ENSEMBLES) over Europe. These patterns are systematically screened for their relevance to the spatial distribution of persistent hot days. Present-day (ERA40) and future (A1B) climate conditions are analyzed. A CART analysis of the ERA40 reanalysis complements the results for the present-day simulations. In many models, long persistent hot days concur with low variabilities of SLP and high water balance deficits both in present and future. However, for the change patterns (A1B minus ERA40) the analysis indicates that the most robust feature is the link between aggravating persistent hot days and increasing surface water deficits. These results highlight that the factors controlling (in our case spatial) variability are not necessarily the same as those controlling associated climate change signals. Since the analysis yields a rather qualitative output, the model bias problems encountered when studying ensemble averages are alleviated.

Orlowsky, B.; Seneviratne, S. I.

2011-07-01

150

The application of the fast, multi-hit, pixel imaging mass spectrometry sensor to spatial imaging mass spectrometry.  

PubMed

Imaging mass spectrometry is a powerful technique that allows chemical information to be correlated to a spatial coordinate on a sample. By using stigmatic ion microscopy, in conjunction with fast cameras, multiple ion masses can be imaged within a single experimental cycle. This means that fewer laser shots and acquisition cycles are required to obtain a full data set, and samples suffer less degradation as overall collection time is reduced. We present the first spatial imaging mass spectrometry results obtained with a new time-stamping detector, named the pixel imaging mass spectrometry (PImMS) sensor. The sensor is capable of storing multiple time stamps in each pixel for each time-of-flight cycle, which gives it multi-mass imaging capabilities within each pixel. A standard velocity-map ion imaging apparatus was modified to allow for microscope mode spatial imaging of a large sample area (approximately 5 × 5 mm(2)). A variety of samples were imaged using PImMS and a conventional camera to determine the specifications and possible applications of the spectrometer and the PImMS camera. PMID:23206074

Brouard, M; Halford, E; Lauer, A; Slater, C S; Winter, B; Yuen, W H; John, J J; Hill, L; Nomerotski, A; Clark, A; Crooks, J; Sedgwick, I; Turchetta, R; Lee, J W L; Vallance, C; Wilman, E

2012-11-01

151

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

PubMed Central

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.

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

2011-01-01

152

The application of local measures of spatial autocorrelation for describing pattern in north Australian landscapes.  

PubMed

This paper tests the use of a spatial analysis technique, based on the calculation of local spatial autocorrelation, as a possible approach for modelling and quantifying structure in northern Australian savanna landscapes. Unlike many landscapes in the world, northern Australian savanna landscapes appear on the surface to be intact. They have not experienced the same large-scale land clearance and intensive land management as other landscapes across Australia. Despite this, natural resource managers are beginning to notice that processes are breaking down and declines in species are becoming more evident. With future declines of species looking more imminent it is particularly important that models are available that can help to assess landscape health, and quantify any structural change that takes place. GIS and landscape ecology provide a useful way of describing landscapes both spatially and temporally and have proved to be particularly useful for understanding vegetation structure or pattern in landscapes across the world. There are many measures that examine spatial structure in the landscape and most of these are now available in a GIS environment (e.g. FRAGSTATS* ARC, r.le, and Patch Analyst). All these methods depend on a landscape described in terms of patches, corridors and matrix. However, since landscapes in northern Australia appear to be relatively intact they tend to exist as surfaces of continuous variation rather than in clearly defined homogeneous units. As a result they cannot be easily described using entity-based models requiring patches and other essentially cartographic approaches. This means that more appropriate methods need to be developed and explored. The approach examined in this paper enables clustering and local pattern in the data to be identified and forms a generic method for conceptualising the landscape structure where patches are not obvious and where boundaries between landscape features are difficult to determine. Two sites are examined using this approach. They have been exposed to different degrees of disturbance by fire and grazing. The results show that savanna landscapes are very complex and that even where there is a high degree of disturbance the landscape is still relatively heterogeneous. This means that treating savanna landscapes as being made up of homogeneous units can limit analysis of pattern, as it can over simplify the structure present, and that methods such as the autocorrelation approach are useful tools for quantifying the variable nature of these landscapes. PMID:11876077

Pearson, Diane M

2002-01-01

153

Mono-detection spatially super resolved microwave imaging for RADAR applications  

NASA Astrophysics Data System (ADS)

In this paper we present a novel RF photonic approach to radar scanning and imaging. The operating principle is based upon a system in which several (in our case two) radiating microwave sources generate and project at far field, a moving grating pattern over an object, e.g. by linearly modifying the relative phase between the microwave sources. Capturing a set of such integrated reflections (we work only with a mono detector) coming from the object at different radio frequencies (due to a simultaneously performed spectral scanning) can spatially reconstruct high resolution image of the object despite the fact that the sensing was performed with a small mono receiving antenna.

Shemer, Amir; Gabay, Isahar; Tur, Moshe; Boag, Amir; Kleinman, Haim; Zach, Shlomo; Zalevsky, Zeev

2012-05-01

154

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

NASA Astrophysics Data System (ADS)

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) In the southern ACF watersheds, mean precipitation generally exhibits a mild decline in early spring and summer and increases in late winter; For the northern ACF watersheds, mean precipitation decreases in summer and increases mildly in winter (as in the south); (iii) In addition to mean trends, the precipitation distributions stretch on both ends with higher highs (floods) and lower lows (droughts). The downscaled temperature and precipitation scenarios are the basis of a comprehensive hydrologic and water resources assessment (reported elsewhere) assessing significant water, agricultural, energy, and environmental sector impacts and underscoring the need for mitigation and adaptation measures.

Zhang, F.; Georgakakos, A. P.

2011-12-01

155

Spatial targeting using queries in a 3-D GIS environment with application to mineral exploration  

NASA Astrophysics Data System (ADS)

A query framework for spatial targeting within a 3-D geographic information system (GIS) software environment is introduced. Input to a query consists of parameters relevant to the query type together with a set of Common Earth Modelling objects represented as point sets, polygonal lines, surfaces, and grids or a region set (subset) thereof. The result of a 3-D GIS query is a region within each of the input objects that consists of nodes or grid cells where the query criteria was satisfied. We provide example scenarios, drawn from mineral exploration, where 3-D queries are used to guide spatial targeting within a near-mine or regional map scale setting. Query types supported are: proximity query (to a “probe” object), property query (numeric attribute), shell query (containment within a closed surface), meta-data query, feature query (dome, depression, curvature), trend query (dip plane, vector) and intersection query (with a “probe” object). Queries can be specific for a given object type but in general transcend object types. Standard set theoretical operations for a query results in newly defined regions and are supported within the Gocad© development environment. This development focuses on queries relevant in the 3-D data integration and interpretation stages of mature geological model development as well as early analysis, typically undertaken before a fully partitioned and attributed 3-D topological model is available.

Sprague, Kevin; de Kemp, Eric; Wong, Winston; McGaughey, John; Perron, Gervais; Barrie, Tucker

2006-04-01

156

Candidate gene prioritization based on spatially mapped gene expression: an application to XLMR  

PubMed Central

Motivation: The identification of genes involved in specific phenotypes, such as human hereditary diseases, often requires the time-consuming and expensive examination of a large number of positional candidates selected by genome-wide techniques such as linkage analysis and association studies. Even considering the positive impact of next-generation sequencing technologies, the prioritization of these positional candidates may be an important step for disease-gene identification. Results: Here, we report a large-scale analysis of spatial, i.e. 3D, gene-expression data from an entire organ (the mouse brain) for the purpose of evaluating and ranking positional candidate genes, showing that the spatial gene-expression patterns can be successfully exploited for the prediction of gene–phenotype associations not only for mouse phenotypes, but also for human central nervous system-related Mendelian disorders. We apply our method to the case of X-linked mental retardation, compare the predictions to the results obtained from a previous large-scale resequencing study of chromosome X and discuss some promising novel candidates. Contact: rosario.piro@unito.it Supplementary information: Supplementary data are available at Bioinformatics online.

Piro, Rosario M.; Molineris, Ivan; Ala, Ugo; Provero, Paolo; Di Cunto, Ferdinando

2010-01-01

157

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

USGS Publications Warehouse

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.

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

2001-01-01

158

The Analysis of Collusive Tendering Based on the Application of Spatial Game  

NASA Astrophysics Data System (ADS)

The bid-rigging on public works projects has recently become social problem in Japan. We can regard this issue as a framework of spatial game through simplifying the strategy of tendering. The main purpose of this study is to represent the tendering with multiple bidders as repeatedly playing games only with the opponents of relationships. We can regard cooperation to occur by performing the repeated games as bid-rigging. To examine the characteristics of this cooperation will lead to the discovery of new knowledge that prevents collusion. From the point of view, in this research by the use of the agent based simulation, we have simulated the tendering recently conducted regarding the disposition of public properties and studied the characteristics of cooperation based on the decision with the suppression of desire. When every group mutually makes the moderate decision, we observe cooperation at high level in the spatial game with the extended strategy expression. On the other hand, it is revealed that the probabilistic change in the connectivity of each group greatly influences that cooperation. This perturbation, therefore, is effective for the deterrence of collusive tendering. In addition, altering multiple parameters, we also show further inspections regarding the obtained results.

Ohdaira, Tetsushi; Terano, Takao

159

Developments in optical system evaluation, spatial modeling, chemometrics and applications with atomic spectroscopy  

NASA Astrophysics Data System (ADS)

High temperature plasma emission sources have spatial characteristics. The Abel inversion calculates radial responses from lateral measurements of cylindrically symmetric emission sources. This dissertation presents three aspects of making spatial measurements: (1) Evaluation of an optical setup; (2) New numerically exact routine for improved spatial modeling; and (3) Radial and lateral measurements. Optical ray tracing software was been used for critical evaluation of the design of a unique imaging spectrometer. Position, area, and angles of view are calculated as a function of position of a translating lens and the optical properties of the quartz tube. The translating lens imaging spectrometer is compared to the more common alternative of moving the source or detector and found to perform comparatively well. A new Abel inversion technique, based on numerical improvements in a matrix-based algorithm, is described. The new approach (Mabel) combines exact computation of area terms for the Abel inversion with matrix calculation capabilities present in the MATLAB TM computational environment to generate radial profiles from lateral scans of the plasma with the best accuracy possible. Results of four 1000 ring Mabel inversions are presented. Comparisons between Mabel and two other numerical methods are made for test cases commonly cited in literature and for test cases having radial and lateral profiles with analytic solutions. The effects of noise propagation and of incomplete viewing of the plasma are also presented. Temperature is one of the most fundamental characteristic of high temperature plasmas. Lateral and radial temperatures measured from different views result in different values for a given plasma emission source. Four radial temperature profiles were used to generate radial intensities of five different wavelengths on the basis of a Boltzmann distribution of energies at each temperature. Forward Mabel transforms were performed on the radial intensities to produce lateral intensity profiles. The temperature at each lateral position can be derived from the slope of a straight line fitted to the natural logarithm of intensity as a function of energy. The modeled radial temperature profiles yield lateral profiles that are dependent on the shape, magnitude of the radial profile, and wavelengths used to measure the temperature.

Rider, Michael Eugene

1998-11-01

160

Application of a dithered sampling technique to increase the spatial resolution of singlet oxygen images  

NASA Astrophysics Data System (ADS)

Singlet molecular oxygen (a1?g) is an intermediate in many important oxidative reactions in heterogeneous biological and polymeric systems. By using a custom-made microscope to detect the 1270 nm phosphorescence of singlet oxygen (a1?g-->X3?g-), singlet oxygen images of such systems can be created. The microscope uses an InGaAs linear photodiode array to detect this extremely weak near infrared phosphorescence. In this article, the effects of the microscope's modulation transfer function and the detector's spatial sampling frequency on the resolution of the images are examined. It is shown that a dithered sampling technique can increase the accessible resolution. In this approach, data are repeatedly acquired from the sample after it has been systematically moved on the microscope stage.

Snyder, John W.; Gao, Zhan; Ogilby, Peter R.

2005-01-01

161

Matched-filter template generation via spatial filtering: application to fetal biomagnetic recordings.  

PubMed

We have developed a two-step procedure for signal processing of fetal biomagnetic recordings that removes cardiac interference and noise. First, a modified matched filter (MF) is applied to remove maternal cardiac interference; then, a simple signal space projection (SSP) is applied to remove noise. The key difference between our MF and a conventional one is that the interference template and the template scaling are derived from a signal that has been spatially filtered to isolate the interference, rather than from the raw signal. Unlike conventional MFs, ours is able to separate maternal and fetal cardiac complexes, even when they have similar morphology and overlap strongly. When followed by a SSP that preserves only the signal subspace, the noise is reduced to a low level. PMID:12374348

Wakai, Ronald T; Lutter, William J

2002-10-01

162

Optimal steering for kinematic vehicles with applications to spatially distributed agents  

NASA Astrophysics Data System (ADS)

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 may be a function of the direction of motion of the vehicle (anisotropic pseudo-distance function) and/or may not be expressible in closed form. Second, such problems fall under the general class of partitioning problems for which the vehicles' dynamics must be taken into account. The topology of the vehicle's configuration space may be non-Euclidean, for example, it may be a manifold embedded in a Euclidean space. In other words, these problems may not be reducible to generalized Voronoi diagram problems for which efficient construction schemes, analytical and/or computational, exist in the literature. This research effort pursues three main objectives. First, we present the complete solution of different steering problems involving a single vehicle in the presence of motion constraints imposed by the maneuverability envelope of the vehicle and/or the presence of a drift field induced by winds/currents in its vicinity. The analysis of each steering problem involving a single vehicle provides us with a state-dependent generalized metric, such as the minimum time-to-go/come. We subsequently use these state-dependent generalized distance functions as the proximity metrics in the formulation of generalized Voronoi-like partitioning problems. The characterization of the solutions of these state-dependent Voronoi-like partitioning problems using either analytical or computational techniques constitutes the second main objective of this dissertation. The third objective of this research effort is to illustrate the use of the proposed concept of state-dependent Voronoi-like partition as a means for passing from control techniques that apply to problems involving a single vehicle to problems involving networks of spatially distributed autonomous vehicles. To this aim, we formulate the problem of sequential/relay pursuit of a maneuvering target by a group of spatially distributed pursuers and subsequently propose a distributed group pursuit strategy that directly derives from the solution of a state-dependent Voronoi-like partitioning problem. (Abstract shortened by UMI.)

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

163

Local and Spatial Joint Frequency Uncertainty and its Application to Rock Mass Characterisation  

NASA Astrophysics Data System (ADS)

Stability is a key issue in any mining or tunnelling activity. Joint frequency constitutes an important input into stability analyses. Three techniques are used herein to quantify the local and spatial joint frequency uncertainty, or possible joint frequencies given joint frequency data, at unsampled locations. Rock quality designation is estimated from the predicted joint frequencies. The first method is based on kriging with subsequent Poisson sampling. The second method transforms the data to near-Gaussian variables and uses the turning band method to generate a range of possible joint frequencies. The third method assumes that the data are Poisson distributed and models the log-intensity of these data with a spatially smooth Gaussian prior distribution. Intensities are obtained and Poisson variables are generated to examine the expected joint frequency and associated variability. The joint frequency data is from an iron ore in the northern part of Norway. The methods are tested at unsampled locations and validated at sampled locations. All three methods perform quite well when predicting sampled points. The probability that the joint frequency exceeds 5 joints per metre is also estimated to illustrate a more realistic utilisation. The obtained probability map highlights zones in the ore where stability problems have occurred. It is therefore concluded that the methods work and that more emphasis should have been placed on these kinds of analyses when the mine was planned. By using simulation instead of estimation, it is possible to obtain a clear picture of possible joint frequency values or ranges, i.e. the uncertainty.

Ellefmo, Steinar L.; Eidsvik, Jo

2009-08-01

164

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

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

165

Evaluating the application of the European spatial development perspective in the United Kingdom: Methodological considerations and emerging trends  

Microsoft Academic Search

The aim of this paper is to consider how the emerging European spatial development policy agenda is influencing the performance of regional strategic planning in the United Kingdom. In May 1999 the Ministers of Spatial Planning meeting at Potsdam, Germany, agreed on the final version of the European Spatial Development Perspective (ESDP) to guide spatially significant public policy making at

Olivier John Sykes

2002-01-01

166

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

PubMed

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 province and department level in Ecuador and Peru, respectively. PMID:22253801

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

2012-01-09

167

Application of spatial TDR-inversion technique during a field experiment in a complex mid mountainous area  

NASA Astrophysics Data System (ADS)

Application of spatial TDR-inversion technique during a field experiment in a complex mid mountainous area Graeff, T., Schlaeger, S., Bauer, A., Morgner, M., Jakisch, C., Bronstert, A., Zehe, E. Transient soil moisture profiles yield valuable information of near surface processes. A recently developed reconstruction algorithm based on the telegraph equation allows the inverse estimation of soil moisture profiles along coated 3-rod TDR probes. This so called Spatial TDR (STDR) technique allows the investigation of highly spatially and temporally resolved soil moisture profiles. The performance of the inversion algorithm is assessed in different laboratory experiments. To validate the STDR technique under field conditions, an irrigation experiment was carried out at a gentle hillslope in a mid mountainous region (Eastern Ore Mountains, Saxony Germany). Complex soil layer structures formed by periglacial processes dominate the experimental site. 40 STDR were installed on an area of 12 m x 12 m. Additionally a TRIME-TDR (Time domain Reflectometry with Intelligent MicroElements) probe was used to measure soil moisture profiles with 10 cm resolution in 5 access tubes of 3 m depth. The irrigation was only accomplished for the upper half of the experimental site to observe the connectivity between the irrigated and the dry half of the experimental site. A brilliant blue dye tracer experiment in the irrigation field was realised for a better understanding of the near surface flow processes. In total 90 mm were irrigated in two experiments within two days. A physically based hillslope model, was used to evaluate the measured profiles of the irrigation experiment. The complex character of the soils leads to a heterogeneous reaction in the subsurface flow processes. We discuss the reliability of the STDR results in context to the experemental setup.

Graeff, T.; Bronstert, A.; Schlaeger, S.; Morgner, M.; Bauer, A.; Jackisch, C.; Zehe, E.

2009-04-01

168

An application of passive samplers to understand atmospheric mercury concentration and dry deposition spatial distributions.  

PubMed

Two modified passive samplers were evaluated at multiple field locations. The sampling rate (SR) of the modified polyurethane foam (PUF)-disk passive sampler for total gaseous mercury (TGM) using gold-coated quartz fiber filters (GcQFF) and gaseous oxidized mercury (GOM) using ion-exchange membranes (IEM) were 6.4 ± 1.4 and 15.3 ± 0.3 m(3) day(-1), respectively. The relative percent difference between TGM and GOM concentrations measured by a Tekran system and the passive samplers averaged 19 ± 14 and 13 ± 12% and ranged between 4-44 and 1.5-41%, respectively. The GcQFF and IEM substrates were also evaluated as collection media for surrogate surface dry deposition measurements. Mercury (Hg) concentration and dry deposition gradients were observed using these samplers at an urban/industrial site and compared to a rural/remote site. The Hg dry deposition rates measured by the surrogate surfaces were always higher than those calculated by a widely used inferential modeling method (1.3-50 fold). The Hg dry deposition measured at urban and suburban sites were comparable to those calculated from model. However, they were very different at a rural site, probably due to the low concentrations. Both methods are relatively low cost and will aid in understanding spatial distributions of Hg ambient air concentrations and dry deposition. PMID:23001454

Huang, Jiaoyan; Choi, Hyun-Deok; Landis, Matthew S; Holsen, Thomas M

2012-11-01

169

Spectral Representation of Spatial Correlations in Variational Assimilation and Application to Stratospheric Chemistry Data Assimilation  

NASA Astrophysics Data System (ADS)

One of the critical aspects of any assimilation system is the formulation of a background error covariance matrix (BECM) which is sufficiently compact to be implemented numerically and sufficiently complex to represent correctly the real error covariances of the first guess field. In the late nineties, meteorological centers have implemented relatively powerful BECM where the spatial correlation matrix is defined in the spectral space. In this configuration, the horizontal correlations are assumed to be homogeneous and isotropic. Moreover, non-separable vertical correlations can be implemented. The goals of this study are numerous. First, it aims at presenting this method by focusing on a univariate assimilation and for global models. Usually, this method is implemented in meteorological spectral models with the physical grid being the (non-equally spaced) Gaussian grid. We will show that the method can be applied directly to equally spaced physical grid without operating a transformation from the Gaussian grid to the model grid, which necessarily degrades the analyses. This method has been implemented in the stratospheric chemistry data assimilation system BASCOE. Hence, the results from real test cases will be shown. In particular, the hypothesis of homogeneity and isotropy will be examined and way forward flow-dependent BECM will be discussed. Finally, a FORTRAN code has been developed and will be made available to the community.

Errera, Q.; Ménard, R.

2012-04-01

170

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

171

Spatial interferometer applications to study PMSE and transient velocity features with the EISCAT VHF radar  

NASA Astrophysics Data System (ADS)

The EISCAT radars have been used intensively over the recent years to study the polar mesosphere summer echoes (PMSE). A summary of these observations was published by Roettger. Dynamical features in the PMSE can show quasi-sinusoidal gravity wave modulations as well as steepening, which is displayed in the Doppler spectra measured with vertically pointing antenna beam. This transient steepening was assumed to be related to the wind corners observed with chaff released from rockets. This steepening feature was so far only observed with VHF radar in the vertical velocity and further proof would be necessary to detect wind corner features also in the horizontal wind. The experiments described here provide this information by applying the spatial interferometer technique introduced to VHF radars by Roettger and Ierkic. We show that this transient steepening is consistent with spontaneous changes of vertical velocity and the horizontal velocity amplitude and direction, which is assumed as a sign of solitary waves. We, thus, have a proper means to study these non-linear processes also with MST radar in the mesopause region.

Roettger, J.; Alcala, C.

1993-08-01

172

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

PubMed Central

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.

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

2011-01-01

173

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

SciTech Connect

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.

Rossow, Molly; Gratton, Enrico [Biomedical Engineering Department, University of California Irvine, Irvine, California (United States); Mantulin, William M. [Beckman Laser Institute, University of California Irvine, Irvine, California (United States)

2009-04-19

174

Comparison of three temperature control systems applications for a special homemade shortwave infrared spatial remote sensor  

NASA Astrophysics Data System (ADS)

An image spectrometer of a spatial remote sensing satellite requires shortwave band ranging from 2.1?m to 3?m which is one of the most important bands in remote sensing. We designed an infrared sub-system of the image spectrometer using a homemade 640x1 InGaAs shortwave infrared sensor working on FPA system which requires high uniformity and low level of dark current. The working temperature should be -15+/-0.2 Degree Celsius. This paper compares three different kinds of methods to control temperature of the sensor. First design uses a temperature control chip Max1978 from Maxim Company. Second design uses ADN8830 from ANALOG Company. Third design is based on FPGA device APA300. Experiment shows that MAX1978 has driving mosfet inside its chip which makes the stability is not appropriate for this homemade shortwave sensor. While the ADN8830 the supply power is limited to 5V, which also limits the driving power of the chip, experiments show that ADN8830 works very well when the voltage is below 5V, but the result is not acceptable when sensor demand more driving current. The FPGA design covers all the disadvantages above, but it introduced a new problem, the electrical circuit takes much more board resources than MAX1978 and ADN8830.

Xu, Zhipeng; Wei, Jun; Li, Jianwei; Zhou, Qianting

2010-11-01

175

Application of a spatially-weighted Relief algorithm for ranking genetic predictors of disease  

PubMed Central

Background Identification of genetic variants that are associated with disease is an important goal in elucidating the genetic causes of diseases. The genetic patterns that are associated with common diseases are complex and may involve multiple interacting genetic variants. The Relief family of algorithms is a powerful tool for efficiently identifying genetic variants that are associated with disease, even if the variants have nonlinear interactions without significant main effects. Many variations of Relief have been developed over the past two decades and several of them have been applied to single nucleotide polymorphism (SNP) data. Results We developed a new spatially weighted variation of Relief called Sigmoid Weighted ReliefF Star (SWRF*), and applied it to synthetic SNP data. When compared to ReliefF and SURF*, which are two algorithms that have been applied to SNP data for identifying interactions, SWRF* had significantly greater power. Furthermore, we developed a framework called the Modular Relief Framework (MoRF) that can be used to develop novel variations of the Relief algorithm, and we used MoRF to develop the SWRF* algorithm. Conclusions MoRF allows easy development of new Relief algorithms by specifying different interchangeable functions for the component terms. Using MORF, we developed a new Relief algorithm called SWRF* that had greater ability to identify interacting genetic variants in synthetic data compared to existing Relief algorithms.

2012-01-01

176

Bayesian hierarchical spatially correlated functional data analysis with application to colon carcinogenesis.  

PubMed

In this article, we present new methods to analyze data from an experiment using rodent models to investigate the role of p27, an important cell-cycle mediator, in early colon carcinogenesis. The responses modeled here are essentially functions nested within a two-stage hierarchy. Standard functional data analysis literature focuses on a single stage of hierarchy and conditionally independent functions with near white noise. However, in our experiment, there is substantial biological motivation for the existence of spatial correlation among the functions, which arise from the locations of biological structures called colonic crypts: this possible functional correlation is a phenomenon we term crypt signaling. Thus, as a point of general methodology, we require an analysis that allows for functions to be correlated at the deepest level of the hierarchy. Our approach is fully Bayesian and uses Markov chain Monte Carlo methods for inference and estimation. Analysis of this data set gives new insights into the structure of p27 expression in early colon carcinogenesis and suggests the existence of significant crypt signaling. Our methodology uses regression splines, and because of the hierarchical nature of the data, dimension reduction of the covariance matrix of the spline coefficients is important: we suggest simple methods for overcoming this problem. PMID:17608780

Baladandayuthapani, Veerabhadran; Mallick, Bani K; Young Hong, Mee; Lupton, Joanne R; Turner, Nancy D; Carroll, Raymond J

2007-06-30

177

Spatial conductivity mapping of carbon nanotube composite thin films by electrical impedance tomography for sensing applications  

Microsoft Academic Search

This paper describes the application of electrical impedance tomography (EIT) to demonstrate the multifunctionality of carbon nanocomposite thin films under various types of environmental stimuli. Carbon nanotube (CNT) thin films are fabricated by a layer-by-layer (LbL) technique and mounted with electrodes along their boundaries. The response of the thin films to various stimuli is investigated by relying on electric current

Tsung-Chin Hou; Kenneth J Loh; Jerome P Lynch

2007-01-01

178

An Open GeoSpatial Standards-Enabled Google Earth Application to Support Crisis Management  

Microsoft Academic Search

Google Earth (GE) and related open geospatial technologies have changed both the accessibility of and audience for geospatial\\u000a information dramatically. Through data rich applications with easy to use interfaces, these technologies bring personalized\\u000a geospatial information directly to the non-specialist. When coupled with open geospatial data standards, such as Web Map Services\\u000a (WMS), Web Features Services (WFS), and GeoRSS, the resulting

Scott Pezanowski; Brian Tomaszewski; Alan M. MacEachren

179

The importance of accurate road data for spatial applications in public health: customizing a road network  

PubMed Central

Background Health researchers have increasingly adopted the use of geographic information systems (GIS) for analyzing environments in which people live and how those environments affect health. One aspect of this research that is often overlooked is the quality and detail of the road data and whether or not it is appropriate for the scale of analysis. Many readily available road datasets, both public domain and commercial, contain positional errors or generalizations that may not be compatible with highly accurate geospatial locations. This study examined the accuracy, completeness, and currency of four readily available public and commercial sources for road data (North Carolina Department of Transportation, StreetMap Pro, TIGER/Line 2000, TIGER/Line 2007) relative to a custom road dataset which we developed and used for comparison. Methods and Results A custom road network dataset was developed to examine associations between health behaviors and the environment among pregnant and postpartum women living in central North Carolina in the United States. Three analytical measures were developed to assess the comparative accuracy and utility of four publicly and commercially available road datasets and the custom dataset in relation to participants' residential locations over three time periods. The exclusion of road segments and positional errors in the four comparison road datasets resulted in between 5.9% and 64.4% of respondents lying farther than 15.24 meters from their nearest road, the distance of the threshold set by the project to facilitate spatial analysis. Agreement, using a Pearson's correlation coefficient, between the customized road dataset and the four comparison road datasets ranged from 0.01 to 0.82. Conclusion This study demonstrates the importance of examining available road datasets and assessing their completeness, accuracy, and currency for their particular study area. This paper serves as an example for assessing the feasibility of readily available commercial or public road datasets, and outlines the steps by which an improved custom dataset for a study area can be developed.

Frizzelle, Brian G; Evenson, Kelly R; Rodriguez, Daniel A; Laraia, Barbara A

2009-01-01

180

Application of a spatial composition spread approach to the preparation of thin film cuprate superconductor libraries  

NASA Astrophysics Data System (ADS)

A spatial composition spread approach was developed to explore the Bi 2Sr2Y(1--x )CaxOy (0?x?1)(Bi-2212) and the La(2--x)Sr xCuO4 (0?x?0.18)(La-214) cuprate systems. Using targets produced on-site, a series of depositions (approximately 75) were made by DC and RF magnetron sputtering to produce films with a linearly varying composition. Various conditions were tested to produce the best quality Bi-2212 and La-214 films. High pressure depositions with a -20 V substrate bias effectively reduced an oxygen resputtering problem, but the resultant film was still rich in Bi and deficient in both Sr and Ca. 'These deficiencies led to phase impurity in the crystallized films. A comprehensive study on the deposition conditions highlighted a problem with using multi-element targets containing both Bi and Ca. Using a modified thermalized gas model, we defined a parameter called the Throughput, to help quantify the experimental trends. Both the Throughput calculations and the experimental data suggested that low pressure depositions would increase both the Sr and Ca concentrations. Low pressure depositions increased the Sr and Ca concentrations in the film. However, even with a substrate bias the film composition was not uniform due to resputtering. The variation of the film composition, caused by the resputtering, again results in a multi-phase film. From the Throughput calculations, the La-214 system was determined to be a more favorable system to study. Initial results from the La-214 system demonstrated the ability to produce a uniform phase across the entire deposition range, and this has been confirmed in recent measurements by another member (Mehran Saadat) of the group. Overall many of the problems associated with depositing cuprate thin-films were overcome, and a simple, yet effective model, was developed to determine which multi-element targets would be suitable for our method.

Sanderson, Robert James

181

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

SciTech Connect

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 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.

Keser, Saniye [Department of Environmental Engineering, Middle East Technical University, 06800 Ankara (Turkey); Duzgun, Sebnem [Department of Mining Engineering, Middle East Technical University, 06800 Ankara (Turkey); Department of Geodetic and Geographic Information Technologies, Middle East Technical University, 06800 Ankara (Turkey); Aksoy, Aysegul, E-mail: aaksoy@metu.edu.tr [Department of Environmental Engineering, Middle East Technical University, 06800 Ankara (Turkey)

2012-03-15

182

Oblique decision trees for spatial pattern detection: optimal algorithm and application to malaria risk  

PubMed Central

Background In order to detect potential disease clusters where a putative source cannot be specified, classical procedures scan the geographical area with circular windows through a specified grid imposed to the map. However, the choice of the windows' shapes, sizes and centers is critical and different choices may not provide exactly the same results. The aim of our work was to use an Oblique Decision Tree model (ODT) which provides potential clusters without pre-specifying shapes, sizes or centers. For this purpose, we have developed an ODT-algorithm to find an oblique partition of the space defined by the geographic coordinates. Methods ODT is based on the classification and regression tree (CART). As CART finds out rectangular partitions of the covariate space, ODT provides oblique partitions maximizing the interclass variance of the independent variable. Since it is a NP-Hard problem in RN, classical ODT-algorithms use evolutionary procedures or heuristics. We have developed an optimal ODT-algorithm in R2, based on the directions defined by each couple of point locations. This partition provided potential clusters which can be tested with Monte-Carlo inference. We applied the ODT-model to a dataset in order to identify potential high risk clusters of malaria in a village in Western Africa during the dry season. The ODT results were compared with those of the Kulldorff' s SaTScan™. Results The ODT procedure provided four classes of risk of infection. In the first high risk class 60%, 95% confidence interval (CI95%) [52.22–67.55], of the children was infected. Monte-Carlo inference showed that the spatial pattern issued from the ODT-model was significant (p < 0.0001). Satscan results yielded one significant cluster where the risk of disease was high with an infectious rate of 54.21%, CI95% [47.51–60.75]. Obviously, his center was located within the first high risk ODT class. Both procedures provided similar results identifying a high risk cluster in the western part of the village where a mosquito breeding point was located. Conclusion ODT-models improve the classical scanning procedures by detecting potential disease clusters independently of any specification of the shapes, sizes or centers of the clusters.

Gaudart, Jean; Poudiougou, Belco; Ranque, Stephane; Doumbo, Ogobara

2005-01-01

183

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

PubMed

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

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

2008-12-24

184

Strategies for real-time spatial analysis using massively parallel SIMD computers: an application to urban traffic flow analysis  

Microsoft Academic Search

The current research focuses upon the development of a methodology for undertaking real-time spatial analysis in a supercomputing environment, specifically using massively parallel SIMD computers. Several approaches that can be used to explore the parallelization characteristics of spatial problems are introduced. Within the focus of a methodology directed toward spatial data parallelism, strategies based on both location-based data decomposition and

Demin Xiong; Duane F. Marble

1996-01-01

185

Novel application of a spatial frequency domain imaging system to determine signature spectral differences between infected and noninfected burn wounds.  

PubMed

Complications of infection can increase burn-related morbidity and mortality. Early detection of burn wound infection could lead to more precise and effective treatment, reducing systemic complications and the need for long-term, broad-spectrum intravenous antibiotics. Quantitative cultures from biopsies are the accepted standard to determine infection. However, this methodology can take days to yield results and is invasive. This investigation focuses on the use of noninvasive imaging to determine the infection status of burn wounds in a controlled in vivo model. Full-thickness burn wounds were created on the dorsum of adult male rats (n = 6). Twenty-four hours after burn wound creation, wounds in the "Infected" group were inoculated with a vehicle containing 1 × 10(8) colony forming unit Staphylococcus aureus. "Control" group animals received vehicle alone. Subsequently, the wounds were imaged daily for a total of 10 days and the differences of skin optical properties were assessed using spatial frequency domain imaging at 16 different wavelengths from 500 to 700 nm. Regions of interest on the resulting images were selected and averaged at each time point. Statistically significant differences in average absorption and reduced scattering coefficients (?(a) and ?(s)') at 620 and 700 nm were observed between the two groups (P < .05). Differential optical properties were most evident by day 4 and persisted throughout the time course. Differential signature changes in optical properties are evident in infected burn wounds. This novel application of spatial frequency domain imaging may prove to be a valuable adjunct to burn wound assessment. Further work will be aimed at determining dose-response relationships and prokaryotic species differences. PMID:23292572

Nguyen, Thu T A; Ramella-Roman, Jessica C; Moffatt, Lauren T; Ortiz, Rachel T; Jordan, Marion H; Shupp, Jeffrey W

186

Using hospitalization for ambulatory care sensitive conditions to measure access to primary health care: an application of spatial structural equation modeling  

Microsoft Academic Search

BACKGROUND: In data commonly used for health services research, a number of relevant variables are unobservable. These include population lifestyle and socio-economic status, physician practice behaviors, population tendency to use health care resources, and disease prevalence. These variables may be considered latent constructs of many observed variables. Using health care data from South Carolina, we show an application of spatial

James N Laditka

2009-01-01

187

An application of spatially constrained inversion using FD Helicopter EM data to characterise spatial variations in groundwater salinity across the floodplains of the Murray River in South-eastern Australia  

NASA Astrophysics Data System (ADS)

The floodplains of the Murray River, situated in the southeast of Australia, have become extensively salinised, related in part to the discharge of naturally saline groundwater linked to increased recharge from land clearing and irrigation adjacent to the river. This problem has been compounded by extended drought conditions that prevail across the Murray Basin, resulting in increase in the accumulation and concentration of salt within the floodplain soils and an increase in salt loads to the river. Consequently in many floodplain areas along the Murray, the native riparian vegetation communities are in severe decline and Eucalyptus largiflorens (Black Box) and E. camaldulensis (Red Gum) communities are being significantly affected. A range management strategies are being employed to manage these issues, the manipulation of river flows to enhance biodiversity values (ie restore vegetation health) and the development of a hydro-dynamic models to better understand surface flows and the role of soils and elevation in floodplain vegetation health. Integral to these strategies is the acquisition of detailed spatial data on the distribution of salinity in floodplain soils and groundwater, thereby indicating patterns of groundwater evapotranspiration and baseflow across these areas. Hydrogeophysical data from electrical (inductive) methods have considerable potential to provide such data. We present an application of the Spatially Constrained Inversion (SCI) of RESOLVE FDHEM (airborne EM) data for defining spatial patterns of salinisation in the sunraysia irrigation area located in the lower Murray Basin of South Australia. Spatially Constrained Inversion uses Delaunay triangulation to set three dimensional constraints between neighbouring soundings, taking advantage of the spatial coherency that may be present in the data set. Conductivity information for individual soundings is linked through the spatial constraints, from well determined parameters to locally poorly determined parameters. For the survey presented here, SCI generated maps detail the spatial variability of floodplain salinisation, the extent of floodplain sediments influenced by lateral recharge and flushing along stretches of the Murray River, and the variability quality of groundwater in deeper semi-confined aquifers. Available borehole and other ancillary information, such as vegetation density and health patterns, match the observed conductivity variations seen in the SCI results, even at the very near surface (~2m depth). The SCI provide more accurate and spatially consistent results compared with those from single site inversions. We also compare the SCI inversion against that generated from a Holistic inversion of the same data set. The results compare well in the near surface, although the observed responses at depth for the latter depart from that expected, with more resistive responses being defined.

Munday, T. J.; Viezzoli, A.; Fitzpatrick, A.

2008-12-01

188

The spatial distribution of overweight and obesity among a birth cohort of young adult Filipinos (Cebu Philippines, 2005): an application of the Kulldorff spatial scan statistic  

PubMed Central

Objectives: The objectives of the study were to test for spatial clustering of obesity in a cohort of young adults in the Philippines, to estimate the locations of any clusters, and to relate these to neighborhood-level urbanicity and individual-level socioeconomic status (SES). Subjects: Data are from a birth cohort of young adult (mean age 22 years) Filipino males (n=988) and females (n=820) enrolled in the Cebu Longitudinal Health and Nutrition Survey. Methods: We used the Kulldorff spatial scan statistic to detect clusters associated with unusually low or high prevalences of overweight or obesity (defined using body mass index, waist circumference and body fat percentage). Cluster locations were compared to neighborhood-level urbanicity, which was measured with a previously validated scale. Individual-level SES was adjusted for using a principal components analysis of household assets. Results: High-prevalence clusters were typically centered in urban areas, but often extended into peri-urban and even rural areas. There were also differences in clustering by both sex and the measure of obesity used. Evidence of clustering in males, but not females, was much weaker after adjustment for SES.

Dahly, D L; Gordon-Larsen, P; Emch, M; Borja, J; Adair, L S

2013-01-01

189

The spatial distribution of overweight and obesity among a birth cohort of young adult Filipinos (Cebu Philippines, 2005): an application of the Kulldorff spatial scan statistic.  

PubMed

Objectives:The objectives of the study were to test for spatial clustering of obesity in a cohort of young adults in the Philippines, to estimate the locations of any clusters, and to relate these to neighborhood-level urbanicity and individual-level socioeconomic status (SES).Subjects:Data are from a birth cohort of young adult (mean age 22 years) Filipino males (n=988) and females (n=820) enrolled in the Cebu Longitudinal Health and Nutrition Survey.Methods:We used the Kulldorff spatial scan statistic to detect clusters associated with unusually low or high prevalences of overweight or obesity (defined using body mass index, waist circumference and body fat percentage). Cluster locations were compared to neighborhood-level urbanicity, which was measured with a previously validated scale. Individual-level SES was adjusted for using a principal components analysis of household assets.Results:High-prevalence clusters were typically centered in urban areas, but often extended into peri-urban and even rural areas. There were also differences in clustering by both sex and the measure of obesity used. Evidence of clustering in males, but not females, was much weaker after adjustment for SES. PMID:23817443

Dahly, D L; Gordon-Larsen, P; Emch, M; Borja, J; Adair, L S

2013-07-01

190

Spatial Variation of Soil Salinity in the Mexicali Valley, Mexico: Application of a Practical Method for Agricultural Monitoring  

NASA Astrophysics Data System (ADS)

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.

Judkins, Gabriel; Myint, Soe

2012-09-01

191

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

SciTech Connect

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.

De Sapio, Vincent

2010-09-01

192

Application of three-dimensional spatial correlation properties of coherent noise in phase noise suppression for digital holographic microscopy  

NASA Astrophysics Data System (ADS)

The inherited coherent noise degrades the phase imaging quality in digital holographic microscopy (DHM). To overcome the problem, an experimental investigation on the three-dimensional (3D) spatial correlation properties of coherent noise is carried out. Multiple blank holograms are recorded without any specimen in DHM setup by consecutively shifting camera along the optical axis, and a series of phase distribution of coherent noise can be obtained by numerical reconstruction. Then, based on the phase distributions, the lateral and longitudinal correlation properties of coherent noise are analyzed by a discrete correlation algorithm. Furthermore, a method for reducing phase noise is proposed by use of multiple holograms. Firstly, a series of holograms are recorded by shifting the camera longitudinally with the step more than longitudinal correlation length of coherent noise field. Secondly, the reconstruction of the holograms leads to a series of phase images of object, in which the coherent noise has different patterns. Consequently, by averaging the phase images, the reductions of phase noise are achieved. The applicability of the method is demonstrated by imaging of the resolution targets and the grating.

Pan, Feng; Xiao, Wen; Liu, Shuo; Rong, Lu

2013-10-01

193

A spatial panel ordered-response model with application to the analysis of urban land-use development intensity patterns  

NASA Astrophysics Data System (ADS)

This paper proposes and estimates a spatial panel ordered-response probit model with temporal autoregressive error terms to analyze changes in urban land development intensity levels over time. Such a model structure maintains a close linkage between the land owner's decision (unobserved to the analyst) and the land development intensity level (observed by the analyst) and accommodates spatial interactions between land owners that lead to spatial spillover effects. In addition, the model structure incorporates spatial heterogeneity as well as spatial heteroscedasticity. The resulting model is estimated using a composite marginal likelihood (CML) approach that does not require any simulation machinery and that can be applied to data sets of any size. A simulation exercise indicates that the CML approach recovers the model parameters very well, even in the presence of high spatial and temporal dependence. In addition, the simulation results demonstrate that ignoring spatial dependency and spatial heterogeneity when both are actually present will lead to bias in parameter estimation. A demonstration exercise applies the proposed model to examine urban land development intensity levels using parcel-level data from Austin, Texas.

Ferdous, Nazneen; Bhat, Chandra R.

2013-01-01

194

A suggested method of estimation for spatial interdependent models with autocorrelated errors, and an application to a county expenditure model  

Microsoft Academic Search

The purpose of this paper is two-fold. First, we describe an estimation procedure that should be useful for spatial models which contain interactions between the dependent variables and autocorrelated error terms. Second, we apply that procedure to a spatial model relating to county police expenditures. Our estimation procedure does not require the specification of the error distribution, and its computational

Harry H. Kelejian; Dennis P. Robinson

1993-01-01

195

An application of Cyclic Signature (CS) clustering for spatial-temporal pattern analysis to support public safety work  

Microsoft Academic Search

In this paper, we propose a novel approach, Cyclic Signature (CS) clustering, to analyze spatial-temporal pattern. CS clustering is based on the calendar regularities of events to analyze spatial-temporal patterns. An experiment, based on a set of reported crime data for a district in Hong Kong, was performed to compare CS clustering against traditional clustering approaches. The results show that

Stephen Chi-fai Chan; Kelvin Leong

2010-01-01

196

Application of GIS Spatial Analysis Method in Landscape Planning and Design —A Case Study of Integrated Land-Use Suitability Analysis of Nanjing Zhongshan Scenic Area  

Microsoft Academic Search

\\u000a Taking integrated land-use suitability analysis of Nanjing Zhongshan Scenic Area for example, the paper implements the application\\u000a of GIS spatial analysis method in landscape planning and design via the comprehensive analysis and evaluation of multifactor.\\u000a The process includes several steps such as collecting basic data, building DEM, and generating analytical diagram, etc.

Yue Xu

197

Application of GIS and Geostatistics to Characterize Spatial Variation of Soil Fluoride on Hang-Jia-Hu Plain, China  

Microsoft Academic Search

Spatial variability of soil fluoride in the plough layer (0–20cm) of paddy soil from Hang-Jia-Hu Plain of Zhejiang Province\\u000a in China was studied using geostatistical analysis and GIS technique. The results of Semivariograms analysis showed that two\\u000a forms of soil fluoride were correlated in a given spatial range, and total fluoride (T-F) was controlled by intrinsic factors\\u000a of parent material,

Zhengmiao Xie; Jing Li; Weihong Wu

2007-01-01

198

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

PubMed

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 and novel results. Future research requires specific modeling for each target species on a road-by-road basis, and measuring the predictive power of model results within similar landscapes. In addition, research that builds on the current literature by investigating rare anomalies and interacting variables will assist in providing sound comprehensive guidelines for wildlife mitigation planning on roads. PMID:21190788

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

2010-12-28

199

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

NASA Astrophysics Data System (ADS)

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 were observed in the different areas of the watershed, related to various land use (riparian forest or agriculture). The first results of fish-habitat association analysis on a 5 km stream are that longitudinal distribution of fish species was mainly impacted by falls associated with ponds. The impact was both due to the barrier effect and to the modification of aquatic habitats. Abundance distribution of Salmo trutta and Cottus gobio was particularly affected. Spatially continuous analysis of fish-habitat relationships allowed us to identify the relative impacts of habitat alteration and presence of physical barriers to fish movements. These techniques could help prioritize preservation and restoration policies in human-impacted watersheds, in particular, identifying the key physical barriers to remove.

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

2009-12-01

200

Alphatome: Enhancing Spatial Reasoning  

NSDL National Science Digital Library

This article from Elizabeth E. LeClair highlights a spatial reasoning exercise and the importance of spatial reasoning ability in many scientific disciplines. The author touches on her own pedagogical experience and how she witnessed her students struggle with spatial reasoning. The article goes on to include details on a 90-minute lab session which is intended to improve spatial reasoning skills and may be applicable in a number of different science and technical classes. Useful graphics are included. This document may be downloaded in PDF file format.

Leclair, Elizabeth E.

2012-02-03

201

Modeling the Spatial Distribution and Fruiting Pattern of a Key Tree Species in a Neotropical Forest: Methodology and Potential Applications  

Microsoft Academic Search

BackgroundThe movement patterns of wild animals depend crucially on the spatial and temporal availability of resources in their habitat. To date, most attempts to model this relationship were forced to rely on simplified assumptions about the spatiotemporal distribution of food resources. Here we demonstrate how advances in statistics permit the combination of sparse ground sampling with remote sensing imagery to

Damien Caillaud; Margaret C. Crofoot; Samuel V. Scarpino; Patrick A. Jansen; Carol X. Garzon-Lopez; Annemarie J. S. Winkelhagen; Stephanie A. Bohlman; Peter D. Walsh; Brock Fenton

2010-01-01

202

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

SciTech Connect

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.

Iida, Yohei; Kado, Shinichiro; Tanaka, Satoru [School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2010-12-15

203

Environme$al Justice and the Spatial Distribution of Outdd'or Recreation sites: au Application of Geographic Information @terns  

Microsoft Academic Search

This study examines the spatial distribution of' outdoor recreation sites and their proximity to census block groups (CBGs), in order to determine potential socio-economic inequities. It is framed within the context of environmental justice. Information from the Southern Appalachian Assessment database was applied to a case study of the Chattahoochee National Forest in North Georgia. Outdoor recreation sites (campgrounds, wilderness

Michael A. Tarrant; H. Ken Cordell

204

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

NASA Astrophysics Data System (ADS)

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.

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

1999-05-01

205

Frame-Rate Spatial Referencing Based on Invariant Indexing and Alignment with Application to On-Line Retinal Image Registration  

Microsoft Academic Search

This paper describes an algorithm to continually and accurately estimate the absolute location of a diagnostic or surgical tool (such as a laser) pointed at the human retina, from a series of image frames. We treat the problem as a registration problem, using diagnostic images to build a spatial map of the retina and then registering each on-line against this

Hong Shen; Charles V. Stewart; Badrinath Roysam; Gang Lin; Howard L. Tanenbaum

206

Frame-Rate Spatial Referencing Based on Invariant Indexing and Alignment with Application to Online Retinal Image Registration  

Microsoft Academic Search

This paper describes an algorithm to continually and accurately estimate the absolute location of a diagnostic or surgical tool (such as a laser) pointed at the human retina, from a series of image frames. We treat the problem as a registration problem using diagnostic images to build a spatial map of the retina and then registering each online image against

Hong Shen; Charles V. Stewart; Badrinath Roysam; Gang Lin; Howard L. Tanenbaum

2003-01-01

207

Correlation and heritability in neuroimaging datasets: A spatial decomposition approach with application to an fMRI study of twins  

PubMed Central

Advances in modern neuroimaging in combination with behavioral genetics have allowed neuroscientists to investigate how genetic and environmental factors shape human brain structure and function. Estimating the heritability of brain structure and function via twin studies has become one of the major approaches in studying the genetics of the brain. In a classical twin study, heritability is estimated by computing genetic and phenotypic variation based on the similarity of monozygotic and dizygotic twins. However, heritability has traditionally been measured for univariate, scalar traits, and it is challenging to assess the heritability of a spatial process, such as a pattern of neural activity. In this work, we develop a statistical method to estimate phenotypic variance and covariance at each location in a spatial process, which in turn can be used to estimate the heritability of a spatial dataset. The method is based on a dimensionally-reduced model of spatial variation in paired images, in which adjusted least squares estimates can be used to estimate the key model parameters. The advantage of the proposed method compared to conventional methods such as a voxelwise or mean-ROI approaches is demonstrated in both a simulation study and a real data study assessing genetic influence on patterns of brain activity in the visual and motor cortices in response to a simple visuomotor task.

Park, Joonkoo; Shedden, Kerby; Polk, Thad A.

2011-01-01

208

A hydrochemical modelling framework for combined assessment of spatial and temporal variability in stream chemistry: application to Plynlimon, Wales  

Microsoft Academic Search

Recent concern about the risk to biota from acidification in upland areas, due to air pollution and land-use change (such as th e planting of coniferous forests), has generated a need to model catchment hydro-chemistry to assess environmental risk and define protection strategies. Previous approaches have tended to concentrate on quantifying either spatial variability at a regional scale or temporal

H. J. Foster; M. J. Lees; H. S. Wheater; C. Neal; B. Reynolds

2001-01-01

209

A hydrochemical modelling framework for combined assessment of spatial and temporal variability in stream chemistry: application to Plynlimon, Wales  

Microsoft Academic Search

Recent concern about the risk to biota from acidification in upland areas, due to air pollution and land-use change (such as the planting of coniferous forests), has generated a need to model catchment hydro-chemistry to assess environmental risk and define protection strategies. Previous approaches have tended to concentrate on quantifying either spatial variability at a regional scale or temporal variability

H. J. Foster; M. J. Lees; H. S. Wheater; C. Neal; B. Reynolds

2001-01-01

210

[Application of carrying capacity assessment in spatial allocation of regional population: a case of Changzhou City of East China].  

PubMed

Based on the spatial differences in urban ecosystem carrying capacity, and by using geographic information system (GIS) spatial analysis technology and system dynamics (SD) model, this paper ascertained the moderate population size in urban area and its subareas, and presented an alternative method for quantitatively allocate the population. This method was applied in Changzhou, a city with more than three million populations in East China. A SD model consisted of population, economy, land and environment modules for the city was established and scenario analysis was made. The results showed that under the requirements of satisfying both economic development and environmental protection, the total population in the city in 2050 would reach nearly 4 million, and according to the differences in the urban ecosystem carrying capacity, a spatial allocation pattern of 2.4 million populations in main city and 150000-400000 populations in each of 5 new towns was proposed. This study could provide scientific support for the spatial allocation of population and economy in country land development and management. PMID:22586976

Chen, Shuang; Wang, Dan; Li, Guang-Yu; Liu, Deng-E; Wu, Song

2012-02-01

211

Improving 3D Spatial Visualization of Stream Channel Morphology: A Geomorphic Application of ArcView 3D Analyst Extension.  

NSDL National Science Digital Library

This laboratory exercise helps student bridge the gap between fieldwork, data collection, visualization, and interpretation of the data. Using a combination of surveying techniques, spreadsheet modeling, and GIS , students further develop their spatial visualization skills and use these skills to predict geomorphic responses.

Van Hoesen, John

212

The intensity regimes of bacteriorhodopsin and its application to large space-bandwidth product spatial phase conjugation  

Microsoft Academic Search

In this talk, we describe the characteristics of the refractive index modulation over a range of incident intensities using the Z-scan method, Then, we demonstrate how a film containing bacteriorhodopsin (BR) is used in real-time large space-bandwidth-product optical spatial phase conjugate holography

Q. Wang Song

1995-01-01

213

Theoretical framework to estimate spatially averaged rainfalls conditional on river discharges and point rainfall measurements from a single location: an application to Western Greece  

NASA Astrophysics Data System (ADS)

We focus on the special case of catchments covered by a single raingauge, and develop a theoretical framework to obtain estimates of spatial rainfall averages conditional on rainfall measurements from a single location, and the flow conditions at the catchment outlet. In doing so we use: (a) statistical tools to identify and correct inconsistencies between daily rainfall occurrence and amount and the flow conditions at the outlet of the basin, (b) concepts from multifractal theory to relate the fraction of wet intervals in point rainfall measurements and that in spatial rainfall averages, while accounting for the shape and size of the catchment, the size, lifetime and advection velocity of rainfall generating features and the location of the raingauge inside the basin, and (c) semi-theoretical arguments to assure consistency between rainfall and runoff volumes at an inter-annual level, implicitly accounting for spatial heterogeneities of rainfall caused by orographic influences. In an application study, using point rainfall records from Glafkos river basin in Western Greece, we find the suggested approach to demonstrate significant skill in resolving rainfall-runoff incompatibilities at a daily level, while reproducing the statistics of spatial rainfall averages at both monthly and annual time scales, independently of the location of the raingauge and the magnitude of the observed deviations between point rainfall measurements and spatial rainfall averages. The developed scheme should serve as an important tool for the effective calibration of rainfall-runoff models in basins covered by a single raingauge and, also, improve hydrologic impact assessment at a river basin level under changing climatic conditions.

Langousis, A.; Kaleris, V.

2012-11-01

214

Theoretical framework to estimate spatial rainfall averages conditional on river discharges and point rainfall measurements from a single location: an application to western Greece  

NASA Astrophysics Data System (ADS)

We focus on the special case of catchments covered by a single rain gauge and develop a theoretical framework to obtain estimates of spatial rainfall averages conditional on rainfall measurements from a single location, and the flow conditions at the catchment outlet. In doing so we use (a) statistical tools to identify and correct inconsistencies between daily rainfall occurrence and amount and the flow conditions at the outlet of the basin; (b) concepts from multifractal theory to relate the fraction of wet intervals in point rainfall measurements and that in spatial rainfall averages, while accounting for the shape and size of the catchment, the size, lifetime and advection velocity of rainfall-generating features and the location of the rain gauge inside the basin; and (c) semi-theoretical arguments to assure consistency between rainfall and runoff volumes at an inter-annual level, implicitly accounting for spatial heterogeneities of rainfall caused by orographic influences. In an application study, using point rainfall records from the Glafkos river basin in western Greece, we find the suggested approach to demonstrate significant skill in resolving rainfall-runoff incompatibilities at a daily level, while reproducing the statistics of spatial rainfall averages at both monthly and annual time scales, independent of the location of the rain gauge and the magnitude of the observed deviations between point rainfall measurements and spatial rainfall averages. The developed scheme should serve as an important tool for the effective calibration of rainfall-runoff models in basins covered by a single rain gauge and, also, improve hydrologic impact assessment at a river basin level under changing climatic conditions.

Langousis, A.; Kaleris, V.

2013-03-01

215

Using expert judgments to understand spatial patterns of forest-based camping: a values-at-risk application.  

PubMed

Fire management agencies in Canada are mandated with protecting multiple forest values from wildfire. Deciding where to reduce fire hazard and how to allocate resources and fire suppression efforts requires an understanding of the values-at-risk from wildfire. The protection of recreation infrastructure is often assumed to provide adequate protection of recreation values. We use an expert judgment approach to provide a spatial distribution of recreation values-at-risk in the forested eastern slopes of the Rocky Mountain region of Alberta, Canada. Data were collected in 2004 from 11 land managers responsible for public lands management and wildfire prevention in the region. Expert assessments showed that recreation values were not confined to areas with publicly funded infrastructure. Exploratory spatial analysis of the ratings identified hotspots and cold spots of recreation activity. Maps resulting from these efforts will provide guidance to fire managers in the prioritization of fire management activities. PMID:17166650

Neupane, Anish; Boxall, Peter C; McFarlane, Bonita L; Pelletier, Rick T

2006-12-12

216

Monte Carlo simulation of spatial resolution for electron backscattered diffraction (EBSD) with application to two-phase materials  

SciTech Connect

The study of texture and grain boundary misorientation in multiphase materials has been greatly benefited from the recent automation of the electron back-scattered diffraction (EBSD) technique. With this technique, each phase in a multiphase material can be individually sampled and analyzed. This is of great significance and interest in the study of thin films, inclusions and multiphase alloys. Spatial resolution, which depends on experimental conditions such as beam energy and specimen tilt, and the material being studied, is critical in order to determine the orientation of different phases in multiphase materials. The Monte Carlo (MC) method has been effectively used to investigate spatial resolution in single phase materials. In this paper, the MC simulation is modified and applied to two-phase geometries, specifically an Al/Au specimen, and a 750 nm thick Au film on a SiO{sub 2} substrate.

Ren, S.X.; Kenik, E.A.; Alexander, K.B.

1997-10-01

217

Translocal spatiality  

Microsoft Academic Search

•Instead of exploring the global\\/local logic of glocalization, this case study specifically concentrates on a form of local-to-local spatial dynamics. The spatial history of Hong Kong underground bandrooms is exploited to illustrate the translocal reproduction of spatiality. While the construction of this space was translocally inspired by music subculture from abroad, local spatiality absorbs transborder subcultural energies and re-channels them

Eric Kit-wai Ma

2002-01-01

218

On the three-fold irregular branched coverings of spatial four-valent graphs and its applications  

Microsoft Academic Search

LetL be a spatial four-valent graph. Then one of the effective tools for studying the topological position ofL in the 3-sphere is to consider the three-fold irregular branched coverings ofL [1]. In this paper we will show that this technique can also be applied to some hypothetical three-valent molecular graphs in topological stereochemistry.

Shin'ichi Kinoshita

1993-01-01

219

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

Microsoft Academic Search

(1) 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

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

2006-01-01

220

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

Microsoft Academic Search

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

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

2006-01-01

221

Modeling the spatial pattern of land-use change with GEOMOD2: application and validation for Costa Rica  

Microsoft Academic Search

The objective of this paper is to simulate the location of land-use change, specifically forest disturbance, in Costa Rica over several decades. This paper presents a GIS-based model, GEOMOD2, which quantifies factors associated with land-use, and simulates the spatial pattern of land-use forward and backward in time. GEOMOD2 reads rasterized maps of land-use and other biogeophysical attributes to determine empirically

R. Gil Pontius Jr; Joseph D. Cornell; Charles A. S. Hall

2001-01-01

222

A generalized method of moments estimator for a spatial model with moving average errors, with application to real estate prices  

Microsoft Academic Search

This paper proposes a new GMM estimator for spatial regression models with moving average errors. Monte Carlo results are\\u000a given which suggest that the GMM estimates are consistent and robust to non-normality, and the Bootstrap method is suggested\\u000a as a way of testing the significance of the moving average parameter. The estimator is applied in a model of English real

Bernard Fingleton

2008-01-01

223

A generalized method of moments estimator for a spatial model with moving average errors, with application to real estate prices  

Microsoft Academic Search

This paper proposes a new GMM estimator for spatial regression models with moving average errors. Monte Carlo results are\\u000a given which suggest that the GMM estimates are consistent and robust to non-normality, and the Bootstrap method is suggested\\u000a as a way of testing the significance of the moving average parameter. The estimator is applied in a model of English real

Bernard Fingleton

224

Regional Variation in the Severity of Pesticide Exposure Outcomes: Applications of Geographic Information Systems and Spatial Scan Statistics  

PubMed Central

Introduction In a previous study, Geographic Information Systems (GIS) and spatial scan statistics were utilized to assess regional clustering of symptomatic pesticide exposure incidents that were reported to a state Poison Control Center (PCC) during a single year. In the current study, we analyzed five subsequent years of PCC data to test whether there are significant geographic differences in pesticide exposure incidents resulting in serious (moderate, major, and fatal) medical outcomes. Methods A Poison Control Center provided data on unintentional pesticide exposure incidents for the time period 2001?2005. Data were abstracted to identify the geographic location of the caller, the location where the exposure occurred, the exposure route, and the medical outcome. Results The results yielded 273 incidents resulting in moderate (n=261), major effects (n=10), or fatalities (n=2). Analysis of these data using spatial scan statistics resulted in the identification of a geographic area consisting of 2 adjacent counties (one urban, one rural) where statistically significant clustering of serious outcomes was observed. The relative risk of moderate, major, and fatal outcomes was 2.0 in this spatial cluster (p=0.0005). Conclusions Poison Control Center data, GIS, and spatial scan statistics can be effectively utilized to identify clustering of serious incidents involving human exposure to pesticides. These analyses may be useful for public health officials to target preventive interventions. Further investigation is warranted to better understand the potential explanations for geographical clustering, and to assess whether preventive interventions have an impact on reducing pesticide exposure incidents resulting in serious medical outcomes.

Sudakin, Daniel L.

2009-01-01

225

[Spatial heterogeneity of wind forcing: application to artificial reef functioning influenced by the circulation in the Bay of Marseilles, France].  

PubMed

In the frame of the largest French project of artificial production reefs, initiated by the city of Marseilles in 2001, the present study aimed at describing the hydrodynamic pattern of the coastal area considered, by the use of a 3D numerical modelling. Results were local wind statistics, bottom current fields and drifting particle maps. The knowledge of the hydrodynamic connexions between particle (such as larvae) sources or targeted areas linked to the reefs, allows us to explain the success or failure of the reefs' colonizing. Moreover, the study confirms the wind spatial variability and demonstrates the error resulting from the use of an average but locally absent wind direction. PMID:16797460

Pradal, Marie-Aude; Millet, Bertrand

2006-06-09

226

Texture-based measurement of spatial frequency response using the dead leaves target: extensions, and application to real camera systems  

NASA Astrophysics Data System (ADS)

The dead leaves model was recently introduced as a method for measuring the spatial frequency response (SFR) of camera systems. The target consists of a series of overlapping opaque circles with a uniform gray level distribution and radii distributed as r-3. Unlike the traditional knife-edge target, the SFR derived from the dead leaves target will be penalized for systems that employ aggressive noise reduction. Initial studies have shown that the dead leaves SFR correlates well with sharpness/texture blur preference, and thus the target can potentially be used as a surrogate for more expensive subjective image quality evaluations. In this paper, the dead leaves target is analyzed for measurement of camera system spatial frequency response. It was determined that the power spectral density (PSD) of the ideal dead leaves target does not exhibit simple power law dependence, and scale invariance is only loosely obeyed. An extension to the ideal dead leaves PSD model is proposed, including a correction term to account for system noise. With this extended model, the SFR of several camera systems with a variety of formats was measured, ranging from 3 to 10 megapixels; the effects of handshake motion blur are also analyzed via the dead leaves target.

McElvain, Jon; Campbell, Scott P.; Miller, Jonathan; Jin, Elaine W.

2010-01-01

227

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

SciTech Connect

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.

Terada, Y.; Tanida, H.; Uruga, T.; Takeuchi, A.; Suzuki, Y.; Goto, S. [Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Koto, Sayo, Hyogo 679-5198 (Japan)

2011-09-09

228

A comparison of the spatial linear model to Nearest Neighbor (k-NN) methods for forestry applications.  

PubMed

Forest surveys provide critical information for many diverse interests. Data are often collected from samples, and from these samples, maps of resources and estimates of aerial totals or averages are required. In this paper, two approaches for mapping and estimating totals; the spatial linear model (SLM) and k-NN (k-Nearest Neighbor) are compared, theoretically, through simulations, and as applied to real forestry data. While both methods have desirable properties, a review shows that the SLM has prediction optimality properties, and can be quite robust. Simulations of artificial populations and resamplings of real forestry data show that the SLM has smaller empirical root-mean-squared prediction errors (RMSPE) for a wide variety of data types, with generally less bias and better interval coverage than k-NN. These patterns held for both point predictions and for population totals or averages, with the SLM reducing RMSPE from 9% to 67% over some popular k-NN methods, with SLM also more robust to spatially imbalanced sampling. Estimating prediction standard errors remains a problem for k-NN predictors, despite recent attempts using model-based methods. Our conclusions are that the SLM should generally be used rather than k-NN if the goal is accurate mapping or estimation of population totals or averages. PMID:23527110

Ver Hoef, Jay M; Temesgen, Hailemariam

2013-03-19

229

Flow of Funds Modeling for Localized Financial Markets: An Application of Spatial Price and Allocation Activity Analysis Models.  

National Technical Information Service (NTIS)

A comprehensive examination of recent and proposed institutional and regulatory changes impacting local financial markets and a summary of the most important applications of mathematical programming to individual financial intermediaries and financial mar...

J. A. Hoskins

1981-01-01

230

INFLUÊNCIA DA VARIABILIDADE ESPACIAL DE ATRIBUTOS QUÍMICOS DE UM LATOSSOLO NA APLICAÇÃO DE INSUMOS PARA CULTURA DE CANA-DE-AÇÚCAR Influence of the spatial variability of latosol chemical attributes and input application for sugarcane culture  

Microsoft Academic Search

Geostatistics and precision agriculture supports on techniques for local application of agricultural amendments at varied rates, has been one of the areas where recent efforts of research and development have been focused. Therefore, the present paper aimed to evaluate lime and phosphorus application needs according to the spatial distribution of soil chemical attributes. Soil samples were collected from 0.0-0.20 m

Zigomar Menezes de Souza; Diogo Mazza Barbieri; José Marques Júnior; Gener Tadeu Pereira; Milton César; Costa Campos

231

Application of spatially averaging optical techniques to the study of short-term flux changes associated with clouds  

SciTech Connect

Cloud formation remains one of the largest uncertainties in Global Circulation Models (GCMs). Most GCM's predict fewer clouds and positive feedback under increased greenhouse gas conditions. However, cloud formation occurs on much smaller scales than GCMs can resolve and is intimately tied to small scale fluxes of heat, water vapor, and cloud condensation nuclei. It is critical to understand how values of these fluxes are distributed is space and time before reliable cloud parameterizations can be expected in GCMs. Doran et al. (1993) describe in this volume an experiment designed to improve our understanding of how point measurements of heat, water vapor and surrogate parameters scale to regional differences in land use (on the order of 10 to 20 km in irrigated agricultural and prairie grassland). Our role was to explore the use of optical techniques to provide spatially-averaged flux and wind convergence measurements and relate these to cloud variability.

Porch, W.; Barnes, F.; Buchwald, M.; Stephens, J.; Archuleta, J.A. (Los Alamos National Lab., NM (United States)); Kunkel, K. (Illinois State Water Survey, Champaign, IL (United States))

1992-01-01

232

Application of spatially averaging optical techniques to the study of short-term flux changes associated with clouds  

SciTech Connect

Cloud formation remains one of the largest uncertainties in Global Circulation Models (GCMs). Most GCM`s predict fewer clouds and positive feedback under increased greenhouse gas conditions. However, cloud formation occurs on much smaller scales than GCMs can resolve and is intimately tied to small scale fluxes of heat, water vapor, and cloud condensation nuclei. It is critical to understand how values of these fluxes are distributed is space and time before reliable cloud parameterizations can be expected in GCMs. Doran et al. (1993) describe in this volume an experiment designed to improve our understanding of how point measurements of heat, water vapor and surrogate parameters scale to regional differences in land use (on the order of 10 to 20 km in irrigated agricultural and prairie grassland). Our role was to explore the use of optical techniques to provide spatially-averaged flux and wind convergence measurements and relate these to cloud variability.

Porch, W.; Barnes, F.; Buchwald, M.; Stephens, J.; Archuleta, J.A. [Los Alamos National Lab., NM (United States); Kunkel, K. [Illinois State Water Survey, Champaign, IL (United States)

1992-10-01

233

Application of validation data for assessing spatial interpolation methods for 8-h ozone or other sparsely monitored constituents.  

PubMed

The adverse health effects of high concentrations of ground-level ozone are well-known, but estimating exposure is difficult due to the sparseness of urban monitoring networks. This sparseness discourages the reservation of a portion of the monitoring stations for validation of interpolation techniques precisely when the risk of overfitting is greatest. In this study, we test a variety of simple spatial interpolation techniques for 8-h ozone with thousands of randomly selected subsets of data from two urban areas with monitoring stations sufficiently numerous to allow for true validation. Results indicate that ordinary kriging with only the range parameter calibrated in an exponential variogram is the generally superior method, and yields reliable confidence intervals. Sparse data sets may contain sufficient information for calibration of the range parameter even if the Moran I p-value is close to unity. R script is made available to apply the methodology to other sparsely monitored constituents. PMID:23624339

Joseph, John; Sharif, Hatim O; Sunil, Thankam; Alamgir, Hasanat

2013-04-27

234

New Developments and Applications of the MP2RAGE Sequence - Focusing the Contrast and High Spatial Resolution R1 Mapping  

PubMed Central

MR structural T1-weighted imaging using high field systems (>3T) is severely hampered by the existing large transmit field inhomogeneities. New sequences have been developed to better cope with such nuisances. In this work we show the potential of a recently proposed sequence, the MP2RAGE, to obtain improved grey white matter contrast with respect to conventional T1-w protocols, allowing for a better visualization of thalamic nuclei and different white matter bundles in the brain stem. Furthermore, the possibility to obtain high spatial resolution (0.65 mm isotropic) R1 maps fully independent of the transmit field inhomogeneities in clinical acceptable time is demonstrated. In this high resolution R1 maps it was possible to clearly observe varying properties of cortical grey matter throughout the cortex and observe different hippocampus fields with variations of intensity that correlate with known myelin concentration variations.

Marques, Jose P.; Gruetter, Rolf

2013-01-01

235

Deposition and characterization of thin ferroelectric lead lanthanum zirconate titanate (PLZT) films on sapphire for spatial light modulators applications.  

PubMed

Ferroelectric lead lanthanum zirconate titanate (PLZT) films are deposited on R-plane sapphire using RF triode magnetron sputtering. Perovskite PLZT films with the desired composition (9/65/35) are obtained using compensated deposition techniques around 500 degrees C and postdeposition annealing at 650 degrees C. The deposited films exhibit good optical and electrooptical properties. The room temperature dielectric constant of the films was 1800 at 10 kHz. The refractive index of the films was in the range of 2.2-2.5. The films showed a quadratic electrooptic effect with R=0.6 x10(-16) m(2)/V(2). The development of PLZT on silicon-on-sapphire smart spatial light modulators using these films is also explored. PMID:18267622

Krishnakumar, S; Ozguz, V H; Fan, C; Cozzolino, C; Esener, S C; Lee, S H

1991-01-01

236

Repeated application of an electric field increases BDNF in the brain, enhances spatial learning, and induces infarct tolerance.  

PubMed

Development of a safe method to increase brain-derived neurotrophic factor (BDNF) in the brain is expected to have utility in enhancing learning and memory, in protecting the brain, and in suppressing appetite. We investigated the effects of whole-body exposure to high voltage electric potential (HELP), which generates an electric field and current density in the body, on BDNF levels in the brain, spatial learning, or resistance to cerebral infarction development after focal ischemia. Adult mice (C57BL/6J) were exposed to 3.5 kV, or 5.8 kV for 5 h a day, making indirect contact with the ground via room air, over 1, 3, 6 or 12 consecutive weeks. After treatment, BDNF levels, performances in the Morris water maze task (MWM), or development of infarct lesion after focal ischemia was analyzed. Treatment with 3.5 kV for 1, 3, 6 or 12 weeks, or with 5.8 kV for 1, 3 or 12 weeks increased BDNF levels in the cortex (P<0.05, one-way ANOVA). Every HELP treatment differentially improved escape latency in the MWM, compared with the corresponding untreated controls (P<0.05, one-way ANOVA). Treatment with 3.5 kV for 6 or 12 weeks, but not with 5.8 kV protected the brain suppressing cerebral infarction development (P<0.05). The HELP treatment with 3.5 kV for 6 or 12 weeks improves spatial learning, gently suppressing body weight gain, and protects the brain against cerebral infarction. PMID:18439988

Yanamoto, Hiroji; Miyamoto, Susumu; Nakajo, Yukako; Nakano, Yoshikazu; Hori, Takuya; Naritomi, Hiroaki; Kikuchi, Haruhiko

2008-03-20

237

Spatial and temporal flushing time approach in estuaries influenced by river and tide. An application in Suances Estuary (Northern Spain)  

NASA Astrophysics Data System (ADS)

Since Water Policies around the world establish the need to manage the aquatic systems through the use of water bodies, a hydromorphological descriptor such as the flushing time may be utilized as a good homogeneity and water quality criterion to distinguish between different types of water bodies. In order to achieve this task, a methodological procedure has been proposed involving a hydrodynamic forcing analysis, an approach to calculate flushing time and a sensitivity analysis of the results applied to the Suances Estuary. This method allows taking into account the different spatial regions on an estuary and the temporal variations of the main forcing. Consequently, the role of bathymetry, freshwater river inflows and oceanic tides on the flushing time is investigated using a two-dimensional numerical model. The hydrodynamic module integrates the depth-averaged mass and momentum equations in the time and space domains as well the transport module solves the depth-averaged advection-diffusion equation. Both modules were calibrated and validated using field data collected during spring and neap tidal cycles. Water levels and current velocities were used in the hydrodynamic module while salinities were compared in the transport module. In order to characterize the spatial variation in water renewal conditions, several boxes were selected along the estuary to evaluate the flushing time. The mass reduction is monitored in time and the flushing time at each part of the estuary was computed for several scenarios and analyzed with a multi-sensitivity analysis.Most of the river estuary basins in Northern Spain are characterized by their small surface area, short length and steepness, leading to a rapid hydrological response to rainfall and, consequently, a high variability in the river flow. During extensive dry periods during which the river flow is very small, pollutants could remain for long periods in the estuary posing an environmental risk.

Bárcena, Javier F.; García, Andrés; Gómez, Aina G.; Álvarez, César; Juanes, José A.; Revilla, José A.

2012-10-01

238

'Location, Location, Location': a spatial approach for rare variant analysis and an application to a study on non-syndromic cleft lip with or without cleft palate  

PubMed Central

Motivation: For the analysis of rare variants in sequence data, numerous approaches have been suggested. Fixed and flexible threshold approaches collapse the rare variant information of a genomic region into a test statistic with reduced dimensionality. Alternatively, the rare variant information can be combined in statistical frameworks that are based on suitable regression models, machine learning, etc. Although the existing approaches provide powerful tests that can incorporate information on allele frequencies and prior biological knowledge, differences in the spatial clustering of rare variants between cases and controls cannot be incorporated. Based on the assumption that deleterious variants and protective variants cluster or occur in different parts of the genomic region of interest, we propose a testing strategy for rare variants that builds on spatial cluster methodology and that guides the identification of the biological relevant segments of the region. Our approach does not require any assumption about the directions of the genetic effects. Results: In simulation studies, we assess the power of the clustering approach and compare it with existing methodology. Our simulation results suggest that the clustering approach for rare variants is well powered, even in situations that are ideal for standard methods. The efficiency of our spatial clustering approach is not affected by the presence of rare variants that have opposite effect size directions. An application to a sequencing study for non-syndromic cleft lip with or without cleft palate (NSCL/P) demonstrates its practical relevance. The proposed testing strategy is applied to a genomic region on chromosome 15q13.3 that was implicated in NSCL/P etiology in a previous genome-wide association study, and its results are compared with standard approaches. Availability: Source code and documentation for the implementation in R will be provided online. Currently, the R-implementation only supports genotype data. We currently are working on an extension for VCF files. Contact: heide.fier@googlemail.com

Fier, Heide; Won, Sungho; Prokopenko, Dmitry; AlChawa, Taofik; Ludwig, Kerstin U.; Fimmers, Rolf; Silverman, Edwin K.; Pagano, Marcello; Mangold, Elisabeth; Lange, Christoph

2012-01-01

239

The SAHGA model to calculate the Spatial Ammoniacal Heterogeneity at the soil surface after fertiliser Granule Application  

Microsoft Academic Search

After dissolution of fertiliser granules, a high nitrogen concentration is recovered in the immediate vicinity of granules, which may enhance damaging processes like nitrite accumulation or ammonia volatilisation. Based on the diffusion equations of Cranck, the granule-soil microsite was modelled to obtain the actual fertilised surface plot and the effective rate of N application on this surface. Parameterisation of the

Edith Le Cadre; Sophie Génermont; Farooq Azam; Sylvie Recous

2004-01-01

240

On the application of MCDA in interactive spatial planning processes: lessons learnt from two stories from the swamp  

Microsoft Academic Search

Rigorous application of Multi-Criteria Decision Analysis (MCDA) is difficult in what Donald Schon (Schon DA. 1983. The Reflecti6e Practitioner: How Professionals Think in Action. Basic Books: New York) characterizes as the swampy lowland where situations are confusing 'messes' incapable of technical solution, but at the same time of greatest human concern. In this article, we report on two cases of

Pieter W. G. Bots

2000-01-01

241

DISCRETE CHOICE MODEL WITH STRUCTURALIZED SPATIAL EFFECTS FOR LOCATION ANALYSIS: A TEST OF APPLICABILITY WITH ZONE AND AREA UNIT SYSTEMS  

Microsoft Academic Search

The present study is a part of continued development of discrete choice models for location analysis. The discrete choice modeling paradigm, and in particular the logit model, are research topics that have been continuously developed and refined for years in the field of transportation applications. Modeling locational choices, on the other hand, differs from modeling transportation choices in that geographically

Kazuaki Miyamoto; Yoshiyuki Tokunaga

242

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)

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.

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

2006-05-01

243

Application of a contact mode AFM for spatially resolved electrochemical impedance spectroscopy measurements of a Nafion membrane electrode assembly.  

PubMed

A Nafion fuel cell membrane is investigated by means of electrochemical atomic force microscopy in different gas atmospheres. From chronoamperometric experiments with a point contact electrode spatially resolved electrochemical impedance spectra are obtained from which information about electrode processes and proton transport in the membrane is derived. In the first part the oxygen reduction reaction is investigated. Due to the absence of diffusion limitation, which is partly a result of the small electrode size, a low frequency inductive loop is observed, which is normally masked in macroscopic electrochemical impedance spectra. The influence of water formation from the oxygen reduction reaction at the cathode is discussed. The second part focuses on a hydrogen/oxygen fuel cell setup. A qualitative explanation is given for the necessity of an applied voltage in addition to the electrochemical potential. Electrochemical impedance spectra obtained at two different positions are compared and fitted based on a Randles-like equivalent circuit. A strongly inhomogeneous performance is observed which is attributed to the properties of the Nafion membrane. The electrolyte resistance and the Nernst impedance are restrictive parameters which describe the diffusion through the membrane. PMID:23080435

Hink, Steffen; Roduner, Emil

2013-02-01

244

Clustering of Fast-Food Restaurants Around Schools: A Novel Application of Spatial Statistics to the Study of Food Environments  

PubMed Central

Objectives. We examined the concentration of fast food restaurants in areas proximal to schools to characterize school neighborhood food environments. Methods. We used geocoded databases of restaurant and school addresses to examine locational patterns of fast-food restaurants and kindergartens and primary and secondary schools in Chicago. We used the bivariate K function statistical method to quantify the degree of clustering (spatial dependence) of fast-food restaurants around school locations. Results. The median distance from any school in Chicago to the nearest fast-food restaurant was 0.52 km, a distance that an adult can walk in little more than 5 minutes, and 78% of schools had at least 1 fast-food restaurant within 800 m. Fast-food restaurants were statistically significantly clustered in areas within a short walking distance from schools, with an estimated 3 to 4 times as many fast-food restaurants within 1.5 km from schools than would be expected if the restaurants were distributed throughout the city in a way unrelated to school locations. Conclusions. Fast-food restaurants are concentrated within a short walking distance from schools, exposing children to poor-quality food environments in their school neighborhoods.

Austin, S. Bryn; Melly, Steven J.; Sanchez, Brisa N.; Patel, Aarti; Buka, Stephen; Gortmaker, Steven L.

2005-01-01

245

Conserved spatially interacting motifs of protein superfamilies: application to fold recognition and function annotation of genome data.  

PubMed

Limitations in techniques for the elucidation of protein function have led to an increasing gap between the annotated proteins and those encoded in a genome. The functional selection and three-dimensional structural constraints of proteins in nature often relate to the retention of significant sequence similarity between proteins of similar fold and function despite poor sequence identity. We identify spatially interacting conserved regions, or motifs, within protein superfamilies that are critical for structure and/or function. A search in sequence databases using these descriptors as additional constraints is an approach to identifying putative additional members of superfamilies. Such constrained searches have been tested against proteins of known structure to demonstrate high percentage specificity (93) with a low error rate of 0.0004. This approach has been compared with other sensitive sequence search methods (e.g., PSI-BLAST, HMMsearch, and IMPALA). It has been extended to analyze the distribution of 11 superfamilies in 93 genomes, including the human genome. PMID:14997562

Bhaduri, Anirban; Ravishankar, R; Sowdhamini, R

2004-03-01

246

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

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 ?m) 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 ?m 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 distribution of targeted metabolites, mainly waxes and flavonoids, was systematically explored on various organs, including flowers, leaves, stems, and roots at high spatial resolution of ~ 12-50 ?m and the changes in the abundance level of these metabolites were monitored on the cer1 mutant with respect to the wild-type. This study revealed the metabolic biology of CER1 gene on each individual organ level with very detailed high spatial resolution. The separate MS images of isobaric metabolites, i.e. C29 alkane vs. C28 aldehyde could be constructed on both genotypes from MS imaging at high mass resolution. This allows tracking of abundance changes for those compounds along with the genetic mutation, which is not achievable with low mass resolution mass spectrometry. This study supported previous hypothesis of molecular function of CER1 gene as aldehyde decarbonylase, especially by displaying hyper accumulation of aldehydes and C30 fatty acid and decrease in abundance of alkanes and ketones in several plant organs of cer1 mutant. The scope of analytes was further directed toward internal cell metabolites from the surface metabolites of the plant. MS profiling and imaging of internal cell metabolites were performed on the vibratome section of Arabidopsis leaf. Vibratome sectioning of the leaf was first conducted to remove the surface cuticle layer and it was followed by enzymatic treatment of the section to induce the digestion of primary cell walls, middle lamella, and expose the internal cells underneath to the surface for detection with the laser by LDI-MS. The subsequent MS imaging onto the enzymatically treated vibratome section allowed us to map the distribution of the metabolites in the internal cell layers, linolenic acid (C18:3 FA) and linoleic acid (C18:2 FA). The development of an assay for relative quantification of analytes at the single subcellular/organelle level by LDI-MS imaging was attempted and both plausibility and significant obstacles were seen. As a test system, native plant organelle, chloroplasts isolated from the spinach leaves were used

Jun, Ji Hyun

2011-11-30

247

Radar target identification using spatial matched filters  

Microsoft Academic Search

The application of spatial matched filter classifiers to the synthetic aperture radar (SAR) automatic target recognition (ATR) problem is being investigated at MIT Lincoln Laboratory. Initial studies investigating the use of several different spatial matched filter classifiers in the framework of a 2D SAR ATR system are summarized. In particular, a new application is presented of a shift-invariant, spatial frequency

Leslie M. Novak; Gregory J. Owirka; Christine M. Netishen

1994-01-01

248

An effective method to detect straight lines from high spatial resolution remotely sensed imagery and its applications for runway extraction  

NASA Astrophysics Data System (ADS)

It has always been an important low-level operation to extract edges from images in the fields of computer vision and image procession, in which straight line extraction is typical and representative. Because most man-made spatial objects, e.g. buildings, roads, etc. often take on near straight-line boundaries, extracting straight lines is often the first step to extract these targets. Straight lines can then be looked as the elementary units for other higher level image interpretations. In this paper, a straight line extraction method combining edge detection and depth-first searching on the vector line layer is proposed and applied to extract runways of airports. The steps include: 1) edges are found with the Canny operator and vectorirzed. The reason to use the Canny operator is because it is designed to be an optimal edge detector, which gives very good results on detecting step or slop like edges. It takes as input a grey scale image, and produces as output an image showing the positions of tracked intensity discontinuities. After this operation, we then vectorize the edge points to be a vector layer with edge tracing.2) With the vector-formatted edge lines, the straight line searching can then be carried out. In order to complete this, topology between arcs should be cleaned and rebuilt, which includes the deletion of repetitive, one-node arcs, and splitting on the intersections, etc. 3) Straight lines are detected with the depth-first searching strategy. With the rebuilt topology, we can easily obtain the begin, end nodes of every line. If the distances of its all vertices to the line connecting the begin, end nodes of an arc are less than some pre-defined threshold, it could be looked as a 'straight line' and extracted. Besides, we are certainly only interested in the straight lines with lengths larger than certain threshold, thus a minimum length threshold should be specified to delete these very short lines. In the searching of straight lines, some arcs should be grouped as a single straight line; some un-straight lines should be split to extract its straight parts. The suitable straight lines are outputted to a vector layer after being reselected and re-grouped, with distinguishing short, long isolating, long not isolating straight lines. With all these steps, we can get the initial straight vector line layer. 4) To these lines with small interspaces but locate on a single straight line, we use a simple but effective connecting step to 'fill' the gaps. Starting from the vector layer and with the operations of broken line connecting and parallel line detection, the main airport runway can be well extracted, which helps us to locate and recognize airports from high spatial remotely sensed imagery.

Wang, Min; Zhang, Xingyue

2007-08-01

249

Retrieval techniques for airborne imaging of methane concentrations using high spatial and moderate spectral resolution: application to AVIRIS  

NASA Astrophysics Data System (ADS)

Two quantitative retrieval techniques were evaluated to estimate methane (CH4) enhancement in concentrated plumes using high spatial and moderate spectral resolution data from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). An Iterative Maximum a Posteriori Differential Optical Absorption Spectroscopy (IMAP-DOAS) algorithm performed well for an ocean scene containing natural CH4 emissions from the Coal Oil Point (COP) seep field near Santa Barbara, California. IMAP-DOAS retrieval precision errors are expected to equal between 0.31 to 0.61 ppm CH4 over the lowest atmospheric layer (height up to 1.04 km), corresponding to about a 30 to 60 ppm error for a 10 m thick plume. However, IMAP-DOAS results for a terrestrial scene were adveresly influenced by the underlying landcover. A hybrid approach using Singular Value Decomposition (SVD) was particularly effective for terrestrial surfaces because it could better account for spectral variability in surface reflectance. Using this approach, a CH4 plume was observed immediately downwind of two hydrocarbon storage tanks at the Inglewood Oil Field in Los Angeles, California, with a maximum near surface enhancement of 8.45 ppm above background. At COP, the distinct plume had a maximum enhancement of 2.85 ppm CH4 above background and was consistent with known seep locations and local wind direction. A sensitivity analysis also indicates CH4 sensitivity should be more than doubled for the next generation AVIRIS sensor (AVIRISng) due to improved spectral resolution and sampling. AVIRIS-like sensors offer the potential to better constrain emissions on local and regional scales, including sources of increasing concern like industrial point source emissions and fugitive CH4 from the oil and gas industry.

Thorpe, A. K.; Frankenberg, C.; Roberts, D. A.

2013-09-01

250

A High Resolution Spatial and Temporal Multiple Doppler Analysis of a Microburst and Its Application to Aircraft Flight Simulation.  

NASA Astrophysics Data System (ADS)

Multiple Doppler radar data collected during the Joint Airport Weather Studies (JAWS) Project is used to synthesize the three-dimensional wind in the region of a microburst. The particular microburst used in this study is the strongest one to date for which three-dimensional winds have been recovered. As a diagnostic tool, a six-degree-of-freedom numerical aircraft model having characteristics similar to Boeing 727 series aircraft is used to investigate jet transport aircraft response to observed microburst winds during simulated approaches and departures. Simple pilot control laws are used to adjust thrust, pitch, roll and yaw so as to maintain given approach or departure parameters. Generally, when horizontal wind shear along the approach or departure path is 10×103 s1 or greater, the model is unable to maintain the desired approach path and suffers a significant reduction in climb performance during a go-around or departure. Although the mean wind shear along a path gives a good qualitative measure of the wind shear threat to a jet transport, different paths with similar mean shears can yield markedly different results, as do the same paths through the microburst at different times. These findings are a direct consequence of the fine temporal and spatial scale of microburst winds. During any given modeled aircraft traverse through the region of highest horizontal shear, time variations in the microburst wind field are shown to have an insignificant effect on the modeled flight path. This is because the traverse period is short (30 s) compared to the lifetime of a microburst (300-600 s).

Elmore, K. L.; McCarthy, J.; Frost, W.; Chang, H. P.

1986-10-01

251

A Bottom up Approach to on-Road CO(2) Emissions Estimates: Improved Spatial Accuracy and Applications for Regional Planning.  

PubMed

On-road transportation is responsible for 28% of all U.S. fossil-fuel CO(2) emissions. Mapping vehicle emissions at regional scales is challenging due to data limitations. Existing emission inventories use spatial proxies such as population and road density to downscale national or state-level data. Such procedures introduce errors where the proxy variables and actual emissions are weakly correlated, and limit analysis of the relationship between emissions and demographic trends at local scales. We develop an on-road emission inventory product for Massachusetts-based on roadway-level traffic data obtained from the Highway Performance Monitoring System (HPMS). We provide annual estimates of on-road CO(2) emissions at a 1 × 1 km grid scale for the years 1980 through 2008. We compared our results with on-road emissions estimates from the Emissions Database for Global Atmospheric Research (EDGAR), with the Vulcan Product, and with estimates derived from state fuel consumption statistics reported by the Federal Highway Administration (FHWA). Our model differs from FHWA estimates by less than 8.5% on average, and is within 5% of Vulcan estimates. We found that EDGAR estimates systematically exceed FHWA by an average of 22.8%. Panel regression analysis of per-mile CO(2) emissions on population density at the town scale shows a statistically significant correlation that varies systematically in sign and magnitude as population density increases. Population density has a positive correlation with per-mile CO(2) emissions for densities below 2000 persons km(-2), above which increasing density correlates negatively with per-mile emissions. PMID:23343173

Gately, Conor K; Hutyra, Lucy R; Wing, Ian Sue; Brondfield, Max N

2013-02-12

252

Evaluation of GaAs Impatt Diodes with High Efficiency for Space Applications Evaluation de Diodes Impatt a Haut Rendement en GaAs pour Applications Spatiales.  

National Technical Information Service (NTIS)

A reliability analysis of epitaxial GaAs IMPATT diodes for space applications is presented. The diodes were subjected to mechanical and climatic tests according to MIL STD 750 B. Long term reliability was evaluated using accelerated life tests. The median...

Bouche Farrayr Hyboi Jarouss Rannea

1977-01-01

253

Spatialized normal come hierarchies  

Microsoft Academic Search

We develop a data structure, the spatialized normal cone hierarchy, and apply it to interactive solutions for model silhouette extraction, local minimum distance computations, and area light source shadow umbra and penumbra boundary determination. The latter applications extend the domain of surface normal encapsulation from problems described by a point and a model to problems involving two models.

David E. Johnson; Elaine Cohen

2001-01-01

254

Spatial decomposition of solvation free energy based on the 3D integral equation theory of molecular liquid: application to miniproteins.  

PubMed

We propose the method of spatial decomposition analysis (SDA) based on three-dimensional integral equation (3D-IE) theory of molecular liquids to study and decompose the thermodynamics of proteins in solution into atomic level contributions. The 3D-IE theory maps the solvation thermodynamic properties, such as the solvation free energy and solvation entropy, onto the 3D space around the solute, including the excluded volume of the solute macromolecule, with the elementary volume contributions expressed in terms of the 3D total and direct correlation functions. The SDA thus breaks down the thermodynamic quantity into partial contributions of the solute fragments (functional groups or residues) by applying the proximity criterion to the 3D-IE mapping onto both the solvation shell outside the solute macromolecule and its excluded volume inside the van der Waals cores, the latter giving a major contribution to the solvation thermodynamics. This is distinct from the previous use of the proximity criterion applied to the 3D distribution functions in the solvation shell only. As SDA does not require perturbing the protein molecule to extract the contributions from the constituent residues, it can become an alternative to the computational "alanine scanning approach". For illustration, we apply SDA to four miniproteins composed of 10-28 amino acid residues (chignolin, CLN025, Trp-cage, and FSD-1) and decompose their solvation free energy into the partial contributions of each residue. The present results show that SDA is capable of detecting a change in the protein thermodynamics due to mutations and local conformational changes. Furthermore, the SDA exhibits a convincing consistency with the experimental values of the whole-residue transfer free energies from water to 1-octanol. Thus, the SDA provides a meaningful decomposition of the protein thermodynamics which can bear a comparison with experimental measurements and therefore can serve as a valuable sensitive tool to analyze the protein thermodynamics at the atomistic resolution level. We envision that the SDA may also serve as a tool for quantitative structure-activity relationships (QSAR) to correlate and predict various solute properties in a fragment-based manner. PMID:21166382

Yamazaki, Takeshi; Kovalenko, Andriy

2010-12-17

255

Spatial Joins Using Seeded Trees  

Microsoft Academic Search

Existing methods for spatial joins assume the existence of indices for the participating data sets. This assumption is not realistic for applications involving multiple map layer overlays or for queries involving non-spatial selections. In this paper, we explore a spatiaJ join method that dynamically constructs index trees called seeded trees at join time. This method uses knowledge of thedata sets

Ming-Ling Lo; Chinya V. Ravishankar

1994-01-01

256

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

PubMed Central

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, southwest Kenya and parts of West Africa. Conclusion We have demonstrated the potential of methods developed in the decision sciences to improve our understanding of uncertainties surrounding the geographical distribution of animal diseases, particularly where information is sparse, and encourage wider application of the decision science methodology in the field of animal health.

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

2006-01-01

257

An Automated Land Analysis System (ALAS) for applications at a range of spatial scales: Watershed to global  

SciTech Connect

Recent advances in Digital Elevation Model (DEM) data availability and topographic analysis have enabled us to develop an Automated Land Analysis System (ALAS). ALAS is based on a series of codes which determine topographic and hydrologic characteristics at each pixel, watershed, and each large scale cell. The input requirements are a DEM from any location in the world, it`s resolution, and array size. A Motif accessed script reads in these inputs and generates a series of data sets which further describe the watershed properties such as flow directions, hydrologic characteristic probability density functions, etc.). Postscript files and arrays indicating the fme river networks and each subcatchment, as well as numerous other properties, are produced and catalogued. The motivation behind the development of ALAS is a direct response to the conceptualization of convergent scales between hydrologic and atmospheric models as defined by the World Climate Research Programme. The remainder of this paper highlights ALAS components, capabilities, and provides some discussion on its applications.

Miller, N.L.

1995-08-01

258

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

PubMed

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

Busch, Martin G; Finsterbusch, Jürgen

2011-04-04

259

Application of aerial photography in combination with GIS for coastal management at small spatial scales: a case study of shellfish aquaculture  

Microsoft Academic Search

Coastal zones are among the planets most threatened ecosystems and effective management of these systems requires spatial\\u000a tools at appropriate spatial scales. Here we apply aerial photography with Geographic Information Systems (GIS), to map the\\u000a cumulative anthropogenic footprint of an industry in a spatially defined ecologically important region of the British Columbian\\u000a coast. Resolution required for such an analysis was

Leah I. Bendell; Peter C. Y. Wan

260

A model of spatial data interoperability on Oracle Spatial  

NASA Astrophysics Data System (ADS)

It has been acclaimed that the future vision for GIS data sharing might look like this: each of small counties or towns hosts its own online GIS; and each uses software and a data model selected to best meet its own needs. This paper gives a model based on Oracle Spatial, within a local government or enterprise the spatial data is in centralized storage, and with metadata interoperability, which enables the organizations to use the proper tool for the job while eliminating complicated data transfers and duplications throughout the enterprise or different departments. The MapInfo and ArcGIS software have been made to work together under the same oracle spatial database use trigger and storage process. On another hand, with the situation of between the departments or enterprises, a three-tier structure solution is given: spatial data server, application server and application client. The application server is a mediation system, this model uses oracle application server as the mediation system, and through the application server the application client sends WMS or WFS request and get the map server for background application. The three-tier structure model exposes a GIS portal which is an online GIS for external applications. Any client can request the server if it accords with WMS or WFS specification.

Zhao, Qiansheng; Huang, Quanyi; Guo, Jiming; Wen, Renqiang

2009-10-01

261

Application of gamma-densitometry tomography to determine phase spatial variation in two-phase and three-phase bubbly flows  

SciTech Connect

Gamma-densitometry tomography is applied to two-phase and three-phase bubbly flows. Spatially resolved measurements of the phase volume fractions are presented for air-water and air-water-sand experiments at various airflow rates. For the conditions examined, the presence of the solid particulate phase had only a minimal effect on the gas volume fraction spatial variation.

Torczynski, J.R.; Adkins, D.R.; Shollenberger, K.A.; O`Hern, T.J.

1995-12-31

262

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)

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.

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

2013-04-01

263

Spatial and multidimensional visualization of Indonesia's village health statistics  

PubMed Central

Background A community health assessment (CHA) is used to identify and address health issues in a given population. Effective CHA requires timely and comprehensive information from a wide variety of sources, such as: socio-economic data, disease surveillance, healthcare utilization, environmental data, and health resource allocation. Indonesia is a developing country with 235 million inhabitants over 13,000 islands. There are significant barriers to conducting CHA in developing countries like Indonesia, such as the high cost of computing resources and the lack of computing skills necessary to support such an assessment. At the University of Pittsburgh, we have developed the Spatial OLAP (On-Line Analytical Processing) Visualization and Analysis Tool (SOVAT) for performing CHA. SOVAT combines Geographic Information System (GIS) technology along with an advanced multidimensional data warehouse structure to facilitate analysis of large, disparate health, environmental, population, and spatial data. The objective of this paper is to demonstrate the potential of SOVAT for facilitating CHA among developing countries by using health, population, healthcare resources, and spatial data from Indonesia for use in two CHA cases studies. Results Bureau of Statistics administered data sets from the Indonesian Census, and the Indonesian village statistics, were used in the case studies. The data consisted of: healthcare resources (number of healthcare professionals and facilities), population (census), morbidity and mortality, and spatial (GIS-formatted) information. The data was formatted, combined, and populated into SOVAT for CHA use. Case study 1 involves the distribution of healthcare professionals in Indonesia, while case study 2 involves malaria mortality. Screen shots are shown for both cases. The results for the CHA were retrieved in seconds and presented through the geospatial and numerical SOVAT interface. Conclusion The case studies show the potential of spatial and multidimensional analysis using SOVAT for community health assessment in developing countries. Since SOVAT is based primarily on open-source components and can be deployed using small personal computers, it is cost-effective for developing countries. Also, combining the strength in analysis and the ease of use makes tools like SOVAT ideal for healthcare professionals without extensive computer skills.

Parmanto, Bambang; Paramita, Maria V; Sugiantara, Wayan; Pramana, Gede; Scotch, Matthew; Burke, Donald S

2008-01-01

264

Benchmarking Spatial Join Operations with Spatial Output  

Microsoft Academic Search

The spatial join operation is benchmarked using variants of well-known spatial data structuressuch as the R-tree, R-tree, R+-tree, and the PMR quadtree. The focus is on a spatialjoin with spatial output because the result of the spatial join frequently serves as input tosubsequent spatial operations (i.e., a cascaded spatial join as would be common in a spatialspreadsheet). Thus, in addition

Erik G. Hoel; Hanan Samet

1995-01-01

265

Thermodynamic Model of Spatial Memory  

NASA Astrophysics Data System (ADS)

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.

Kaufman, Miron; Allen, P.

1998-03-01

266

Fractal analysis of spatial and temporal variability  

Microsoft Academic Search

Characterizing spatial and temporal variability is important in variable rate (VRAT) or long-term studies. This study was conducted to compare spatial variability of soil nitrate in a VRAT nitrogen (N) application study and temporal variability of soybean (Glycine max L.) yield in a long-term organic vs. inorganic study. In the VRAT study, conventional uniform N application was compared with variable

Bahman Eghball; Gary W. Hergert; Gary W. Lesoing; Richard B. Ferguson

2000-01-01

267

Implicit interaction profiling for recommending spatial content  

Microsoft Academic Search

When individuals request task-relevant spatial content in the form of area maps, GIS applications typically return default maps displaying standard map content. Little effort is made by these applications to present users with personalized maps displaying spatial content tailored to users' specific interests. Maps generated usually contain superfluous information that hinders the user's end goal and is irrelevant in terms

Joe Weakliam; Michela Bertolotto; David C. Wilson

2005-01-01

268

Progress in Spatial Analysis: Introduction  

Microsoft Academic Search

\\u000a With its roots in geography and regional science spatial analysis has experienced remarkable growth in recent years in terms\\u000a of theory, methods, and applications. The series of books, that in the past decade have collected research in spatial analysis\\u000a and econometrics, provide both documented evidence and a powerful platform to further this upwards trend. Among the collections\\u000a that have done

Antonio Páez; Julie Gallo; Ron N. Buliung; Sandy Dall’Erba

269

Amorphous silicon spatial light modulator  

NASA Astrophysics Data System (ADS)

This patent application discloses an amorphous silicon spatial light modulator that includes a unique three electrode structure that is used to create a two-dimensional electric field distribution in liquid crystal material. This modulator allows for the use of very thin photoconductor layers and a middle electrode in the form of a grating structure to provide control of the field shape while also providing for high spatial resolution.

Ashley, P. R.

1985-12-01

270

Spatial scaling of net primary productivity using subpixel information  

Microsoft Academic Search

Spatial scaling is of particular importance in remote sensing applications to terrestrial ecosystems where spatial heterogeneity is the norm. Surface parameters derived at different resolutions can be considerably different even though they are derived using the same algorithms. This article addresses issues related to spatial scaling of net primary productivity (NPP). The main objective is to develop algorithms for spatial

Anita Simic; Jing M. Chen; Jane Liu; Ferko Csillag

2004-01-01

271

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  

Microsoft Academic Search

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

Yo Matsubara; Alan D. Howard

2009-01-01

272

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

|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"…

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

273

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

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"…

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

274

Improved quality of computed tomography substitute derived from magnetic resonance (MR) data by incorporation of spatial information - potential application for MR-only radiotherapy and attenuation correction in positron emission tomography.  

PubMed

Abstract Background. Estimation of computed tomography (CT) equivalent data, i.e. a substitute CT (s-CT), from magnetic resonance (MR) images is a prerequisite both for attenuation correction of positron emission tomography (PET) data acquired with a PET/MR scanner and for dose calculations in an MR-only radiotherapy workflow. It has previously been shown that it is possible to estimate Hounsfield numbers based on MR image intensities, using ultra short echo-time imaging and Gaussian mixture regression (GMR). In the present pilot study we investigate the possibility to also include spatial information in the GMR, with the aim to improve the quality of the s-CT. Material and methods. MR and CT data for nine patients were used in the present study. For each patient, GMR models were created from the other eight patients, including either both UTE image intensities and spatial information on a voxel by voxel level, or only UTE image intensities. The models were used to create s-CT images for each respective patient. Results. The inclusion of spatial information in the GMR model improved the accuracy of the estimated s-CT. The improvement was most pronounced in smaller, complicated anatomical regions as the inner ear and post-nasal cavities. Conclusions. This pilot study shows that inclusion of spatial information in GMR models to convert MR data to CT equivalent images is feasible. The accuracy of the s-CT is improved and the spatial information could make it possible to create a general model for the conversion applicable to the whole body. PMID:23984810

Johansson, Adam; Garpebring, Anders; Karlsson, Mikael; Asklund, Thomas; Nyholm, Tufve

2013-08-29

275

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

PubMed Central

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 quantifying exposure pathways to dioxins from industrial sources, relative to background exposures.

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

2008-01-01

276

Video Games and Spatial Cognition  

Microsoft Academic Search

Video game enthusiasts spend many hours at play, and this intense activity has the potential to alter both brain and behavior. We review studies that investigate the ability of video games to modify processes in spatial cognition. We outline the initial stages of research into the underlying mechanisms of learning, and we also consider possible applications of this new knowledge.

Ian Spence; Jing Feng

2010-01-01

277

Spatial Thinking Strategies  

NSDL National Science Digital Library

While some people consider spatial thinking a "gift" that only some individuals have, many others view spatial thinking as a cognitive process that can be developed. Much research supports the developmental view of spatial thinking as a cognitive process,

Everett, Susan

2000-04-01

278

Performance of Data-Parallel Spatial Operations  

Microsoft Academic Search

The performance of data-parallel algorithms for spatial operations using data-parallel variants of the bucket PMR quadtree, R-tree, and R+-tree spatial data structures is com- pared. The studied operations are data struc- ture build, polygonization, and spatial join in an application domain consisting of pla- nar line segment data. The algorithms are implemented using the scan model of paral- lel computation

Erik G. Hoel; Hanan Samet

1994-01-01

279

Advection scheme with 3rd high-order spatial interpolation at the middle temporal level and its application to saltwater intrusion in the Changjiang Estuary  

Microsoft Academic Search

A non-oscillatory advection scheme with 3rd high-order spatial interpolation at the middle temporal level coupled with a TVD limiter (the 3rd HSIMT-TVD scheme) was developed with the following features: (1) It uses a parabola to characterize a substance’s local distribution at n?t; (2) it determines the cell interface value at (n+0.5)?t by one-step backward tracing to its position at n?t;

Hui Wu; Jianrong Zhu

2010-01-01

280

A spatial model for the needle losses of pine-trees in the forests of Baden-Württemberg: an application of Bayesian structured additive regression  

Microsoft Academic Search

The data that are analysed are from a monitoring survey which was carried out in 1994 in the forests of Baden-Württemberg, a federal state in the south-western region of Germany. The survey is part of a large monitoring scheme that has been carried out since the 1980s at different spatial and temporal resolutions to observe the increase in forest damage.

Nicole H. Augustin; Stefan Lang; Monica Musio; Klaus von Wilpert

2007-01-01

281

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)

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.

Smith, Hugh; Blake, William; Taylor, Alex

2013-04-01

282

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  

Microsoft Academic Search

Mortality during movement between habitat patches is the most obvious cost of dispersal, but rarely it has been demonstrated\\u000a empirically. An approach is presented, which uses capture–mark–recapture data of an arboreal gecko species to determine the\\u000a effect of individual movement on local survival in a spatially structured population. Because capture–mark–recapture data\\u000a are widely available for a range of animal species,

Bernd Gruber; Klaus Henle

2008-01-01

283

Spatial analysis of lung, colorectal, and breast cancer on Cape Cod: An application of generalized additive models to case-control data  

PubMed Central

Background The availability of geographic information from cancer and birth defect registries has increased public demands for investigation of perceived disease clusters. Many neighborhood-level cluster investigations are methodologically problematic, while maps made from registry data often ignore latency and many known risk factors. Population-based case-control and cohort studies provide a stronger foundation for spatial epidemiology because potential confounders and disease latency can be addressed. Methods We investigated the association between residence and colorectal, lung, and breast cancer on upper Cape Cod, Massachusetts (USA) using extensive data on covariates and residential history from two case-control studies for 1983–1993. We generated maps using generalized additive models, smoothing on longitude and latitude while adjusting for covariates. The resulting continuous surface estimates disease rates relative to the whole study area. We used permutation tests to examine the overall importance of location in the model and identify areas of increased and decreased risk. Results Maps of colorectal cancer were relatively flat. Assuming 15 years of latency, lung cancer was significantly elevated just northeast of the Massachusetts Military Reservation, although the result did not hold when we restricted to residences of longest duration. Earlier non-spatial epidemiology had found a weak association between lung cancer and proximity to gun and mortar positions on the reservation. Breast cancer hot spots tended to increase in magnitude as we increased latency and adjusted for covariates, indicating that confounders were partly hiding these areas. Significant breast cancer hot spots were located near known groundwater plumes and the Massachusetts Military Reservation. Discussion Spatial epidemiology of population-based case-control studies addresses many methodological criticisms of cluster studies and generates new exposure hypotheses. Our results provide evidence for spatial clustering of breast cancer on upper Cape Cod. The analysis suggests further investigation of the potential association between breast cancer and pollution plumes based on detailed exposure modeling.

Vieira, Veronica; Webster, Thomas; Weinberg, Janice; Aschengrau, Ann; Ozonoff, David

2005-01-01

284

Hierarchical additive modeling of nonlinear association with spatial correlations--an application to relate alcohol outlet density and neighborhood assault rates.  

PubMed

Previous studies have suggested a link between alcohol outlets and assaults. In this paper, we explore the effects of alcohol availability on assaults at the census tract level over time. In addition, we use a natural experiment to check whether a sudden loss of alcohol outlets is associated with deeper decreasing in assault violence. Several features of the data raise statistical challenges: (1) the association between covariates (for example, the alcohol outlet density of each census tract) and the assault rates may be complex and therefore cannot be described using a linear model without covariates transformation, (2) the covariates may be highly correlated with each other, (3) there are a number of observations that have missing inputs, and (4) there is spatial association in assault rates at the census tract level. We propose a hierarchical additive model, where the nonlinear correlations and the complex interaction effects are modeled using the multiple additive regression trees and the residual spatial association in the assault rates that cannot be explained in the model are smoothed using a conditional autoregressive (CAR) method. We develop a two-stage algorithm that connects the nonparametric trees with CAR to look for important covariates associated with the assault rates, while taking into account the spatial association of assault rates in adjacent census tracts. The proposed method is applied to the Los Angeles assault data (1990-1999). To assess the efficiency of the method, the results are compared with those obtained from a hierarchical linear model. PMID:19402025

Yu, Qingzhao; Li, Bin; Scribner, Richard Allen

2009-06-30

285

A scan statistic for binary outcome based on hypergeometric probability model, with an application to detecting spatial clusters of Japanese encephalitis.  

PubMed

As a useful tool for geographical cluster detection of events, the spatial scan statistic is widely applied in many fields and plays an increasingly important role. The classic version of the spatial scan statistic for the binary outcome is developed by Kulldorff, based on the Bernoulli or the Poisson probability model. In this paper, we apply the Hypergeometric probability model to construct the likelihood function under the null hypothesis. Compared with existing methods, the likelihood function under the null hypothesis is an alternative and indirect method to identify the potential cluster, and the test statistic is the extreme value of the likelihood function. Similar with Kulldorff's methods, we adopt Monte Carlo test for the test of significance. Both methods are applied for detecting spatial clusters of Japanese encephalitis in Sichuan province, China, in 2009, and the detected clusters are identical. Through a simulation to independent benchmark data, it is indicated that the test statistic based on the Hypergeometric model outweighs Kulldorff's statistics for clusters of high population density or large size; otherwise Kulldorff's statistics are superior. PMID:23785424

Zhao, Xing; Zhou, Xiao-Hua; Feng, Zijian; Guo, Pengfei; He, Hongyan; Zhang, Tao; Duan, Lei; Li, Xiaosong

2013-06-13

286

Discovery of General Knowledge in Large Spatial Databases  

Microsoft Academic Search

Extraction of interesting and general knowledge from large spatial databases is animportant task in the development of spatial data- and knowledge-base systems. In thispaper, we investigate knowledge discovery in spatial databases and develop ageneralization-based knowledge discovery mechanism which integrates attribute-orientedinduction on nonspatial data and spatial merge and generalization on spatial data. Thestudy shows that knowledge discovery has wide applications in

Wei Lu; Jiawei Han; Beng Chin Ooi

1993-01-01

287

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)

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 by SCN infestation. Comparison of estimators such as -2 RLL, AIC, and BIC of non-spatial and spatial models affirmed that incorporating spatial covariance structure of observations improved model performances. These results demonstrated a limited potential of aerial imaging and ground level spectrometry for detecting nematode infestation in the field. However, it is strongly recommended that more multisite-multiyear trials must be performed to establish and validate empirical models to quantify SCN population densities and their impact on soybean canopy reflectance.

Kulkarni, Subodh

288

Hierarchical clustering of spatially correlated functional data  

Microsoft Academic Search

Abstract Classiflcation problems of functional data arise naturally in many applications. Several approaches have been considered for solving the problem of flnding groups based on func- tional data. In this paper we are interested in detecting groups when the functional data are spatially correlated. Our methodology allows to flnd spatially homogeneous groups of sites when the observations at each sampling

Ramon Giraldo; Pedro Delicado; Jorge Mateu

289

Spatial light modulators using ferroelectric liquid crystal  

Microsoft Academic Search

Basic structures and functions of optically addressed spatial light modulators (SLMs) are discussed in the context of system applications. The most important functions imposed on spatial light modulators are those of image acceptance and transducers. SLMs using ferroelectric liquid crystal (FLC) satisfy essential requirements for high levels of resolution, sensitivity and response speed. We specifically surveyed the current performance of

T. Kurokawa; S. Fukushima

1992-01-01

290

Transverse spatial transport in field-effect transistors based on heterostructures with selective doping and the limits of applicability of quasi-hydrodynamic models  

SciTech Connect

For field-effect transistors based on heterostructures with selective doping, the results of calculations for the output characteristics of devices on the basis of the hydrodynamic model are compared with those based on the quasi-hydrodynamic (temperature-related) model. It is shown that the transverse spatial transport and heavy dependences of relaxation times on energy lead to the situation where the results of calculations based on the above models differ appreciably from one another at the gate lengths that much exceed the length of electron relaxation by momentum.

Klimova, A. V. [Federal State Unitary Corporation Istok (Russian Federation)], E-mail: solidstate10@mail.ru; Lukashin, M. V. [Research Institute MEIIT MIEM (Russian Federation); Pashkovskii, A. B. [Federal State Unitary Corporation Istok (Russian Federation)

2009-01-15

291

Asymmetries in Spatial Semantics  

Microsoft Academic Search

abstract sense. This simple fact marks the importance of Ewald Lang's cognitive linguistic work on the semantics of spatial adjectives (long, wide, high etc. ) or spatial dimension terms (Lang 2001). His treatment of the dimensional designation of spatial objects (Lang 1987, 1989) includes assumptions about the conceptual representation of spatial objects which are empirically grounded and theoretically well motivated

Kai-uwe Carstensen

292

Beyond Location Based - The Spatially Aware Mobile Phone  

Microsoft Academic Search

An increasing number of mobile phones feature embedded sensors such as GPS receivers, digital compasses or accelerometer-based tilt sensors. In this paper, we present an application framework for building spatially aware mobile applications - applications that visualize, process or exchange geo- spatial information - on mobile phones equipped with such sensors. The core component of the framework is a novel,

Rainer Simon; Peter Fröhlich; Hermann Anegg

2006-01-01

293

Spatial representation of soundscape  

NASA Astrophysics Data System (ADS)

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.

Boubezari, Mohammed; Bento Coelho, Jos-Luis

2001-05-01

294

SpatialNews  

NSDL National Science Digital Library

The applications of geographic information systems (GIS) grow with each passing day, and more people are interested in careers in this field. The SpatialNews site is a good way for students and professionals in the GIS field to stay on top of new developments via their feature articles, RSS feeds, and discussion boards. There is a great deal of information on the homepage, and first-time visitors should start by looking over the sections on "GIS Education", "Features", and "Business Bit & Bytes". Some of the more notable feature articles profile the history of GIS, the use of GIS in the military, and the use of GIS during hurricane evacuations. The site is rounded out by a listing of job opportunities and selected comments from the discussion boards.

295

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)

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 processes such as glacier/snow melt, surface runoff, baseflow and evapotranspiration. We test the coupled glacio-hydrologic model performance through comparison of predicted variations in glacier extent, snow water equivalent and streamflow discharge with satellite estimates of glacier area and terminus position combined with stream discharge and observed snow data. Our initial results show the effects on the hydrology of the Bow River as related to retreat of the glacier and its replacement with seasonal snow cover, and the differences in melt and runoff generation associated with this transition.

Naz, B. S.; Frans, C. D.; Clarke, G. K.; Nolin, A. W.; Lettenmaier, D. P.; Istanbulluoglu, E.; Burns, P. J.

2011-12-01

296

A high-spatial-resolution fiber-optic-coupled CMOS imager with novel scintillator for high-energy x-ray applications  

NASA Astrophysics Data System (ADS)

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.

Baur, Robin M.; Tate, Mark W.; Dale, Darren S.; Gruner, Sol M.

2013-03-01

297

New developments and applications of the MP2RAGE sequence--focusing the contrast and high spatial resolution R1 mapping.  

PubMed

MR structural T1-weighted imaging using high field systems (>3T) is severely hampered by the existing large transmit field inhomogeneities. New sequences have been developed to better cope with such nuisances. In this work we show the potential of a recently proposed sequence, the MP2RAGE, to obtain improved grey white matter contrast with respect to conventional T1-w protocols, allowing for a better visualization of thalamic nuclei and different white matter bundles in the brain stem. Furthermore, the possibility to obtain high spatial resolution (0.65 mm isotropic) R1 maps fully independent of the transmit field inhomogeneities in clinical acceptable time is demonstrated. In this high resolution R1 maps it was possible to clearly observe varying properties of cortical grey matter throughout the cortex and observe different hippocampus fields with variations of intensity that correlate with known myelin concentration variations. PMID:23874936

Marques, José P; Gruetter, Rolf

2013-07-16

298

Hidden negative spatial autocorrelation  

NASA Astrophysics Data System (ADS)

Mostly lip service treatments of negative spatial autocorrelation (NSA) appear in the literature, although spatial scientists confront it in practice. NSA was detected serendipitously in recalcitrant empirical analyses containing a sizeable amount of global positive spatial autocorrelation (PSA) unaccounted for by standard spatial statistical models, and labeled hidden because conventional spatial statistical tools detected only PSA while giving absolutely not hint of NSA existing. The meaning of this phenomenon is explored empirically, with findings including: a better understanding of NSA, spatial filter model construction guidelines, effective illustrations of NSA, and how hidden NSA furnishes a diagnostic for model misspecification.

Griffith, Daniel A.

2006-10-01

299

Spatial Analysis of Linguistic Data with GIS Functions  

Microsoft Academic Search

During the 1980s techniques for analysis of geographical patterns have been refined to the point that they may be applied to data from many fields. Quantitative spatial analysis and existing functions available in geographical information systems (GIS) enable computerized implementations of these spatial analysis methods. This paper describes the application of quantitative spatial analysis and GIS functions to analysis of

Jay Lee; William A. Kretzschmar Jr.

1993-01-01

300

GIS technology and spatial analysis in coastal zone management  

Microsoft Academic Search

This paper reviews methods and tools of spatial analysis, their integration and application to coastal zone management. Following a definition of the coastal zone and a short description of its peculiarities and unique management problems, the paper first describes the major tools for spatial analysis, and in particular, GIS and remote sensing, spatially distributed simulation modeling and optimization, and expert

Kurt Fedra; Enrico Feoli

1998-01-01

301

Multiscale Histograms: Summarizing Topological Relations in Large Spatial Datasets  

Microsoft Academic Search

Summarizing topological relations is fundamen- tal to many spatial applications including spatial query optimization. In this paper, we present sev- eral novel techniques to eectiv ely construct cell density based spatial histograms for range (win- dow) summarizations restricted to the four most important topological relations: contains, con- tained, overlap, and disjoint. We rst present a novel framework to construct a

Xuemin Lin; Qing Liu; Yidong Yuan; Xiaofang Zhou

2003-01-01

302

Investigating the spatial micro-epidemiology of diseases within a point-prevalence sample: a field applicable method for rapid mapping of households using low-cost GPS-dataloggers  

PubMed Central

Summary Point-prevalence recording of the distribution of tropical parasitic diseases at village level is usually sufficient for general monitoring and surveillance. Whilst within-village spatial patterning of diseases exists, and can be important, mapping infected cases in a household-by-household setting is arduous and time consuming. With the development of low-cost GPS-data loggers (< £40) and available GoogleEarthTM satellite imagery, we present a field-applicable method based on crowdsourcing for rapid identification of infected cases (intestinal schistosomiasis, malaria and hookworm) by household. A total of 126 mothers with their 247 preschool children from Bukoba village (Mayuge District, Uganda) were examined with half of these mothers given a GPS-data logger to walk home with, returning the unit the same day for data off-loading, after which, households were assigned GPS coordinates. A satellite image of Bukoba was annotated with households denoting the infection status of each mother and child. General prevalence of intestinal schistosomiasis, malaria and hookworm in mothers and children was: 27.2 vs 7.7%, 28.6 vs 87.0% and 60.0 vs 22.3%, respectively. Different spatial patterns of disease could be identified likely representing the intrinsic differences in parasite biology and interplay with human behaviour(s) across this local landscape providing a better insight into reasons for disease micro-patterning.

Stothard, J. Russell; Sousa-Figueiredo, Jose C.; Betson, Martha; Seto, Edmund Y.W.; Kabatereine, Narcis B.

2011-01-01

303

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)

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.

Matsubara, Yo; Howard, Alan D.

2009-06-01

304

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

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.

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

305

Comparing the applicability of some geostatistical methods to predict the spatial distribution of topsoil Calcium Carbonate in part of farmland of Zanjan Province  

NASA Astrophysics Data System (ADS)

Most of soils in iran, were located in the arid and semi-arid regions and have high pH (more than 7) and high amount of calcium carbonate and this problem cause to their calcification.In calcareous soils, plant growing and production is difficult. Most part of this problem, in relation to high pH and high concentration of calcium ion that cause to fixation and unavailability of elements which were dependent to pH, especially Phosphorous and some micro nutrients such as Fe, Zn, Mn and Cu. Prediction of soil calcium carbonate in non-sampled areas and mapping the calcium carbonate variability in order to sustainable management of soil fertility is very important.So, this research was done with the aim of evaluation and analyzing spatial variability of topsoil calcium carbonate as an aspect of soil fertility and plant nutrition, comparing geostatistical methods such as kriging and co-kriging and mapping topsoil calcium carbonate. For geostatistical analyzing, sampling was done with stratified random method and soil samples from 0 to 15 cm depth were collected with auger within 23 locations.In co-kriging method, salinity data was used as auxiliary variable. For comparing and evaluation of geostatistical methods, cross validation were used by statistical parameters of RMSE. The results showed that co-kriging method has the highest correlation coefficient and less RMSE and has the higher accuracy than kriging method to prediction of calcium carbonate content in non-sampled areas.

Sarmadian, Fereydoon; Keshavarzi, Ali

2010-05-01

306

High-Efficiency Thomson Scattering Measurement System and Its Application to Spatially Resolved EEDF Measurement of Surface-Wave Excited Plasma  

NASA Astrophysics Data System (ADS)

A high-efficiency Thomson scattering measurement system was constructed, which consists of a triple-grating spectrograph (TGS) and an ICCD camera. TGS has a f number of 3.6 and is equipped with a spatial notch filter (1 nm width, ˜ 10-9 rejection) for suppressing Rayleigh light. The plasma is irradiated with a frequency doubled Nd:YAG laser (532 nm, 300 mJ, 30 pps) and the photocathode of the ICCD camera is optimized for visible light detection. Thomson signal level in the present system is expected to be a facotor of ˜ 20 higher than our previous system (Rev. Sic. Instrum. 71, 2716 (2000)). The plasma chamber has a diameter of 40 cm and an axial (horizontal) length of 30 cm. The chamber is movable in a horizontal plane, while the (vertical) laser beam axis is fixed; the laser beam can approach as close as 1 mm to the end quarts plate, through which a surface wave plasma is excited. Thus two-dimensional EEDF measurements in the region of strong surface wave excitatoin can be performed. Preliminary measurements indicate a promising performance of the measurement system. (The work supported by the 21st Century COE Program from the Ministry of Education, Culture, Sports, Science and Technology in Japan)

Kono, A.; Kobayashi, J.; Aramaki, M.; Stamate, E.; Sugai, H.

2003-10-01

307

Spatial Reasoning and Adults.  

ERIC Educational Resources Information Center

|This monograph contains two studies in which the notion of intelligence as one general basic ability is rejected and in its place is posited the existence of a specific type of mental ability described as "spatial intelligence.""Spatial Reasoning and Its Measurement" investigates the process of spatial reasoning in the adult through an analysis…

La Pierre, Sharon D.; Fellenz, Robert A.

308

Memoz - Spatial Weblogging  

NASA Astrophysics Data System (ADS)

The article argues that spatial webpublishing has influence on weblogging, and calls for a revision of the current weblog definition. The weblog genre should be able to incorporate spatial representation, not only the sequential ordering of articles. The article show examples of different spatial forms, including material produced in Memoz (MEMory OrganiZer).

Hoem, Jon

309

Application of Multi-Criteria Decision Analysis to Geoelectric and Geologic Parameters for Spatial Prediction of Groundwater Resources Potential and Aquifer Evaluation  

NASA Astrophysics Data System (ADS)

Prediction of groundwater resources potential is a spatial decision problem that involves a set of multiple evaluation parameters. In order to produce a groundwater resources potential prediction model of higher reliability and precision in a given study area, the effects of all the important parameters that can contribute to the groundwater occurrence in the area must be integrated. However, the methodology of integrating these parameters such that the relative importance of each is reflected is still a challenge that has not been efficiently handled. In this study, the principle of multi-criteria decision analysis in the context of the analytical hierarchy process is proposed as a technique that can yield a prediction model of higher reliability and precision. The proposed technique was applied to geoelectric and geologic parameters, derived from the results of the interpretation of 2D resistivity imaging data acquired from the study area. The advantage of the proposed technique is that it reduces bias in decision making. The main objective of the study is to produce groundwater potential map for the area. Furthermore, an attempt was also made in the study to characterize the aquifer of the area by estimating the Dar-Zarrouk parameters, using the integration of borehole and 2D resistivity data. The success rate (accuracy) of the prediction was established to be 80 %. Furthermore, the regression line fitted to the aquifer transmissivity and transverse resistance data shows linear relationship with a high regression coefficient of 0.79. The prediction success rate obtained showed that the method proposed in this study is reliable, accurate, and an improved technique of integrating multiple parameters for holistic evaluation of groundwater resources.

Adiat, K. A. N.; Nawawi, M. N. M.; Abdullah, K.

2013-03-01

310

Agent-Based Distributed Component Services in Spatial Modeling  

Microsoft Academic Search

Agent technologies have been increasingly applied to spatial simulation and modeling in silico. Where multi-agent systems have been used for spatial simulation, agents have tended to be deployed as spatial objects in\\u000a order to study emergent patterns from micro-level behaviors. Many of these applications only deploy a weak notion of agency.\\u000a More recently, the concept has emerged in the spatial

Allan J. Brimicombe; Yang Li; Abdullah Al-zakwani; Chao Li

2009-01-01

311

Image sequence coding using spatial/spatial-frequency representations  

NASA Astrophysics Data System (ADS)

Spatial/spatial-frequency representations have proven to be an interesting and powerful framework for the simulation of a number of visual effects. Results consistent with observations of the human visual system have been obtained at levels ranging from the shape of receptive field profiles to perceptual grouping and texture segmentation. A number of representations are under study, in a number of different fields. A key issue in comparing these representations is the resolution that can be attained (simultaneously) in the joint domain. The uncertainty principle dictates that arbitrarily high resolution cannot be achieved in both space and spatial-frequency. Joint resolution can range from singular functions in space (with infinite extent in spatial-frequency), to the reverse (e.g., the pixel representation at one extreme, and the Fourier transform at the other). In this paper, we discuss some of the available representations in the context of image sequence coding, and establish some of the characteristics desired in a representation for this application. We show that the joint resolution of a representation, in particular, can affect the performance of coding methods based on that representation. Examples which illustrate this point using industry standard DCT-based methods are given.

Reed, Todd R.

1992-08-01

312

Projecting land use transitions at forest fringes in the Philippines at two spatial scales  

Microsoft Academic Search

This paper presents two applications of a spatially explicit model of land use change at two spatial scales: a nation-wide application for the Philippines at relatively coarse resolution and an application with high spatial resolution for one island of the Philippines: Sibuyan island, Romblon province. The model is based on integrated analysis of socio-economic and biophysical factors that determine the

Peter H. Verburg; A. Veldkamp

2004-01-01

313

Spatially-Heterodyned Holography  

DOEpatents

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.

Thomas, Clarence E [Knoxville, TN; Hanson, Gregory R [Clinton, TN

2006-02-21

314

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)

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 facility. A significant rise in the concentration of fusion events was found outside of the anode, believed to be due in part from negative ions. The FIDO and TOF Diagnostics have proven to be valuable additions to the study of IEC devices and have greatly advanced IEC operation and theory.

Donovan, David C.

315

Modularizing Spatial Ontologies for Assisted Living Systems  

NASA Astrophysics Data System (ADS)

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.

Hois, Joana

316

Applications  

NASA Astrophysics Data System (ADS)

Economic incentives have spurred numerous applications of genetically engineered organisms in manufacture of pharmaceuticals and industrial chemicals. These successes, involving a variety of methods of genetic manipulation, have dispelled early fears that genetic engineering could not be handled safely, even in the laboratory. Consequently, the potential for applications in the wider environment without physical containment is being considered for agriculture, mining, pollution control, and pest control. These proposed applications range from modest extensions of current plant breeding techniques for new disease-resistant species to radical combinations of organisms (for example, nitrogen-fixing corn plants). These applications raise concerns about potential ecological impacts (see chapter 5), largely because of adverse experiences with both deliberate and inadvertent introductions of nonindigenous species.

Stern, Arthur M.

1986-07-01

317

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

NASA Astrophysics Data System (ADS)

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 to represent spatial variables in a more efficient way. The hyper-population consists of a set of populations, which correspond to the spatial distributions of the individual agents (organisms). Furthermore spatial crossover and mutation operators are designed in accordance with the tree representation and then applied to both organisms and populations. This study applies the SEA to a specific problem of water resources management- maximizing the riparian vegetation coverage in accordance with the distributed groundwater system in an arid region. The vegetation coverage is impacted greatly by the nonlinear feedbacks and interactions between vegetation and groundwater and the spatial variability of groundwater. The SEA is applied to search for an optimal vegetation configuration compatible to the groundwater flow. The results from this example demonstrate the effectiveness of the SEA. Extension of the algorithm for other water resources management problems is discussed.

Wang, J.; Cai, X.

2007-12-01

318

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)

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 as the quantitative measure to select optimal analyzing parameters. The SSEK indicator is robuster in evaluating the impulsiveness intensity of vibration signals due to its better suppressing ability of Gaussian noise, harmonics and sporadic impulsive shocks. Numerical validations, an experimental test and two engineering applications were used to verify the effectiveness of the proposed technique. The analyzing results of the numerical validations, experimental tests and engineering applications demonstrate that the proposed technique possesses robuster transient vibration content detecting performance in comparison with the original FK and the WPT-based FK method, especially when they are applied to the processing of vibration signals of relative limited duration.

Chen, BinQiang; Zhang, ZhouSuo; Zi, YanYang; He, ZhengJia; Sun, Chuang

2013-10-01

319

Remote Access to Active Spatial Data Repositories  

Microsoft Academic Search

Active spatial data repositories managed by object-oriented DBMSs will play an increasing role in achieving inter- operability between extremely heterogeneous geo-scientific applications. GeoToolKit is an open object-oriented framework primarily intended for maintaining 3D-objects in the object-oriented DBMS ObjectStore . In this paper we focus on three alternative access paradigms to spatial data repositories built on top of GeoToolKit . The

Oleg Balovnev; Andreas Bergmann; Martin Breunig; Armin B. Cremers; Serge Shumilov

1999-01-01

320

Energy Transfer through Photorefractive Spatial Soliton Interaction  

NASA Astrophysics Data System (ADS)

In this research, we investigate the interaction between colliding photorefractive spatial solitons. The energy transfer from a vector soliton to a scalar soliton is quantitatively investigated. The energy exchange efficiency increases as the input intensity ratio of the vector soliton increases, while it decreases as the collision angle increases. It is also found that the spatial solitons interact with each other like particles, and the energy of each soliton is conserved after the collision. This observation provides preliminary data for optical computation applications via photorefractive spatial solitons.

Liang, Bao-Lai; Guo, Qing-Lin; Jiang, Yi-Hui; Wang, Ying; Zhang, Su-Heng; Fu, Guang-Sheng

2013-06-01

321

Applications  

NASA Astrophysics Data System (ADS)

Welding, brazing, and soldering are thermal processes used to join material. Laser technology has been applied for these processes for many years. The main principle of all laser-supported joining technologies is the absorption of laser radiation near to the contact area of the joining partners and — if used — also at the filler material, the transformation of the radiation energy into heat and the transition of part of the irradiated material into the molten (metals) or plasticized (polymers) state. This phase transformation allows the creation of a solid joint by resolidification of the molten or plasticized volume and bridging the gap between the joining partners. This happens spatially behind the interaction zone being moved along the joint track or simply temporally after the laser is switched off.

Petring, D.; Polzin, R.; Becker, M.

322

Application of Spatial Data Modeling and Geographical Information Systems (GIS) for Identification of Potential Siting Options for Various Electrical Generation Sources  

SciTech Connect

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 contiguous United States. If a cell meets the requirements of each criterion, the cell is deemed a candidate area for siting a specific power generation form relative to a reference plant for that power type. Some SSEC parameters preclude siting a power plant because of an environmental, regulatory, or land-use constraint. Other SSEC assist in identifying less favorable areas, such as proximity to hazardous operations. All of the selected SSEC tend to recommend against sites. The focus of the ORNL electrical generation source siting study is on identifying candidate areas from which potential sites might be selected, stopping short of performing any detailed site evaluations or comparisons. This approach is designed to quickly screen for and characterize candidate areas. Critical assumptions supporting this work include the supply of cooling water to thermoelectric power generation; a methodology to provide an adequate siting footprint for typical power plant applications; a methodology to estimate thermoelectric plant capacity while accounting for available cooling water; and a methodology to account for future ({approx}2035) siting limitations as population increases and demands on freshwater sources change. OR-SAGE algorithms were built to account for these critical assumptions. Stream flow is the primary thermoelectric plant cooling source evaluated in this study. All cooling was assumed to be provided by a closed-cycle cooling (CCC) system requiring makeup water to account for evaporation and blowdown. Limited evaluations of shoreline cooling and the use of municipal processed water (gray) cooling were performed. Using a representative set of SSEC as input to the OR-SAGE tool and employing the accompanying critical assumptions, independent results for the various power generation sources studied were calculated.

Mays, Gary T [ORNL; Belles, Randy [ORNL; Blevins, Brandon R [ORNL; Hadley, Stanton W [ORNL; Harrison, Thomas J [ORNL; Jochem, Warren C [ORNL; Neish, Bradley S [ORNL; Omitaomu, Olufemi A [ORNL; Rose, Amy N [ORNL

2012-05-01

323

Algorithms for Spatial Outlier Detection  

Microsoft Academic Search

A spatial outlier is a spatially referenced object whose non-spatial attribute values are significantly different from the values of its neighborhood. Identification of spatial outliers can lead to the discovery of unexpected, interesting, and useful spatial patterns for further analysis. One drawback of existing methods is that normal objects tend to be falsely detected as spatial outliers when their neighborhood

Chang-tien Lu; Dechang Chen; Yufeng Kou

2003-01-01

324

Spatial cointegration and heteroscedasticity  

NASA Astrophysics Data System (ADS)

A two-step Lagrange Multiplier test strategy has recently been suggested as a tool to reveal spatial cointegration. The present paper generalises the test procedure by incorporating control for unobserved heteroscedasticity. Using Monte Carlo simulation, the behaviour of several relevant tests for spatial cointegration and/or heteroscedasticity is investigated. The two-step test for spatial cointegration appears to be robust towards heteroscedasticity. While several tests for heteroscedasticity prove to be inconclusive under certain circumstances, a Lagrange Multiplier test for heteroscedasticity based on spatially differenced variables is shown to serve well as an indication of heteroscedasticity irrespective of cointegration status.

Lauridsen, Jørgen; Kosfeld, Reinhold

2007-09-01

325

Quantify spatial relations to discover handwritten graphical symbols  

NASA Astrophysics Data System (ADS)

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.

Li, Jinpeng; Mouchère, Harold; Viard-Gaudin, Christian

2012-01-01

326

Rapid spatially scanning ir heterodyne interferometer.  

PubMed

An interferometer has been developed which provides repetitive spatial profiles of phase objects in the ir using a single detector channel. By combining Bragg cell heterodyne interferometry with a high speed (0.5 million rpm) turbine driven rotating mirror scanner, the system effectively converts temporal fringes to spatial fringes. Designed for applications in plasma diagnostics, the system scans a 5-cm field with a 2-mm resolution in 200 nsec. Operating in a double pass mode at 3.4 microm, the phase accuracy is better than 0.1 fringe. The concept is applicable over a wide range in wavelength, scan format, and resolution. PMID:20208789

Kristal, R

1979-03-01

327

Discriminative spatial pyramid  

Microsoft Academic Search

Spatial Pyramid Representation (SPR) is a widely used method for embedding both global and local spatial information into a feature, and it shows good performance in terms of generic image recognition. In SPR, the image is divided into a sequence of increasingly finer grids on each pyramid level. Features are extracted from all of the grid cells and are concatenated

Tatsuya Harada; Yoshitaka Ushiku; Yuya Yamashita; Yasuo Kuniyoshi

2011-01-01

328

Non-spatial government  

Microsoft Academic Search

This article explores the evolution of government. Facilitated by advances in telecommunications and information technology, governments of the future may become specialized by function. One type of government will be non-spatial in essence and will be populated by people who share a strong affinity with each other, but not necessarily common spatial boundaries. A second type of government will necessarily

Bruce E Tonn; David Feldman

1995-01-01

329

SPATIAL INTERACTION DATA  

Microsoft Academic Search

The lack of good flow data is a handicap to spatial interaction researth, yet many published works provide little evaluation of such data. Good quality flow data should provide spatial coverage at a large scale with small sampling and other error components. Few generally available data series for interregional commodity flows, interregional population migration, and intercity person movement in the

Derek Thompson

1974-01-01

330

Clustering of estimated spatial locations in networked sensors  

NASA Astrophysics Data System (ADS)

Multisensor data fusion combines data from multiple sensors to overcome interferences that may not be possible from a single sensor or source alone. In military application data fusion can be used to integrate the individual sensor data into common operational picture of the battlefield. However, there is still possibility to improve quality of the individual sensor. Improving of accuracy in estimation of spatial location is investigated in this paper. Some novel methods and algorithms for estimation of spatial location are compared such as Discrete Probability Density (DPD) method, fusion of multiple bearing lines and mean-square distance algorithm. These methods for estimation of spatial location use two-step positioning technique (indirect technique) based on estimation of a specified parameter such as angle of arrival (AOA). In the network where is possible to provide multiple spatial locations from the spatially close sources, clustering of estimated spatial location is very important. The estimated spatial locations that correspond to a source are spatially close to one another will have a larger likelihood than those estimated spatial locations that are not correspond to the source. In this paper methods and algorithms for estimation of spatial location are compared where it is multiple spatial locations, for the same sources spatially close. Clustering has been performed based on estimated spatial locations and appropriates the covariance matrix.

Pokrajac, Ivan P.; Okiljevic, Predrag; Vracar, Miodrag

2013-05-01

331

Intelligent Rollups in Multidimensional OLAP Data  

Microsoft Academic Search

In this paper we propose a new operator for advanced exploration of large multidimensional databases. The proposed operator can automati- cally generalize from a specific problem case in detailed data and return the broadest context in which the problem occurs. Such a functional- ity would be useful to an analyst who after ob- serving a problem case, say a drop

Gayatri Sathe; Sunita Sarawagi

2001-01-01

332

Proxy-server architectures for OLAP  

Microsoft Academic Search

Data warehouses have been successfully employed for assisting decision making by offering a global view of the enterprise data and providing mechanisms for On-Line Analytical processing. Traditionally, data warehouses are utilized within the limits of an enterprise or organization. The growth of Internet and WWW however, has created new opportunities for data sharing among ad-hoc, geographically spanned and possibly mobile

Panos Kalnis; Dimitris Papadias

2001-01-01

333

Spatial filters for complex wavefront modulation.  

PubMed

In this paper we propose a method to generate independent and simultaneous phase and amplitude modulation by a phase-only spatial light modulator and Fourier filtering. The incident light is modulated by a suitable phase pattern containing high spatial frequencies. The modulated light is transmitted through a 4f optical system having an appropriate spatial filter in the Fourier plane in order to synthesize the expected complex modulated wavefront on the output of the system. We propose a simple method to generate spatial filters applicable for the phase-only to complex modulated wavefront conversion. We analyze the quality of the output image related to the ideal wavefront using the proposed filters. We show that more efficient complex modulation can be realized by the proposed method than by the earlier solutions. PMID:23913064

Sarkadi, Tamás; Kettinger, Adám; Koppa, Pál

2013-08-01

334

The spatial rotator.  

PubMed

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

Rasmusson, A; Hahn, U; Larsen, J O; Gundersen, H J G; Jensen, E B Vedel; Nyengaard, J R

2013-03-12

335

Spatial occupancy models for large data sets  

USGS Publications Warehouse

Since its development, occupancy modeling has become a popular and useful tool for ecologists wishing to learn about the dynamics of species occurrence over time and space. Such models require presence–absence data to be collected at spatially indexed survey units. However, only recently have researchers recognized the need to correct for spatially induced overdisperison by explicitly accounting for spatial autocorrelation in occupancy probability. Previous efforts to incorporate such autocorrelation have largely focused on logit-normal formulations for occupancy, with spatial autocorrelation induced by a random effect within a hierarchical modeling framework. Although useful, computational time generally limits such an approach to relatively small data sets, and there are often problems with algorithm instability, yielding unsatisfactory results. Further, recent research has revealed a hidden form of multicollinearity in such applications, which may lead to parameter bias if not explicitly addressed. Combining several techniques, we present a unifying hierarchical spatial occupancy model specification that is particularly effective over large spatial extents. This approach employs a probit mixture framework for occupancy and can easily accommodate a reduced-dimensional spatial process to resolve issues with multicollinearity and spatial confounding while improving algorithm convergence. Using open-source software, we demonstrate this new model specification using a case study involving occupancy of caribou (Rangifer tarandus) over a set of 1080 survey units spanning a large contiguous region (108?000 km2) in northern Ontario, Canada. Overall, the combination of a more efficient specification and open-source software allows for a facile and stable implementation of spatial occupancy models for large data sets.

Johnson, Devin S.; Conn, Paul B.; Hooten, Mevin B.; Ray, Justina C.; Pond, Bruce A.

2013-01-01

336

Mining Preferences from Spatial-Temporal Data  

Microsoft Academic Search

The discovery of preferences in space and time is important in a variety of applications. In this paper we first establish the correspondence between a set of preferences in space and time and density estimates obtained from observations of spatial-temporal features recorded within large databases. We perform density estimation using both kernel methods and mixture models. The density estimates constitute

Donald E. Brown; Hua Liu; Yifei Xue

337

Spatial resolution enhancement of ASTER thermal bands  

Microsoft Academic Search

Image fusion aims at the exploitation of the information conveyed by data acquired by different imaging sensors. A notable application is merging images acquired from space by panchromatic and multi- or hyper-spectral sensors that exhibit complementary spatial and spectral resolution. Multiresolution analysis has been recognized efficient for image fusion. The Generalized Laplacian Pyramid (GLP), in particular, has been proven as

Bruno Aiazzi; Luciano Alparone; Stefano Baronti; Leonardo Santurri; Massimo Selva

2005-01-01

338

Geologic spatial analysis  

SciTech Connect

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)

Thiessen, R.L.; Eliason, J.R.

1989-01-01

339

ET Spatial Techniques  

NSDL National Science Digital Library

This site from ET Spatial Techniques profiles reasonably priced, highly functional software for the ArcView/ArcGIS professionals. Links to information and free dowloads can also be found on this site.

Techniques, Et S.

340

Spatial Structure: Patch Models  

Microsoft Academic Search

Discrete spatial heterogenity is introduced into disease transmission models, resulting in large systems of ordinary differential\\u000a equations. Such metapopulation models describe disease spread on a number of spatial patches. In the first model considered,\\u000a there is no explicit movement of individuals; rather infectives can pass the disease to susceptibles in other patches. The\\u000a second type of model explicitly includes rates

P. van den Driessche

341

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 ...

342

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...

343

Spatial Query Processing in Wireless Sensor Networks - A Survey  

Microsoft Academic Search

Wireless sensor networks (WSN) are particularly useful for obtaining data concerning events limited to a well-defined geographic region, such as a disaster site or a malfunctioning subsection of a factory plant. Such applications tipically use spatial queries, which are SQL-like queries where location constraints are imposed on the collected data. Further, spatial queries allow changing the set of nodes (the

Rone Ilídio da Silva; Daniel Fernandes Macedo; José Marcos S. Nogueira

2012-01-01

344

RISK ASSESSMENT USING SPATIAL PREDICTION MODEL FOR NATURAL DISASTER PREPAREDNESS  

Microsoft Academic Search

The spatial mapping of risk is critical in planning for disaster preparedness. An application from a study area affected by mass movements is used as an example to portray the desirable relations between hazard prediction and disaster management. We have developed a three-stage procedure in spatial data analysis not only to estimate the probability of the occurrence of the natural

Chang-Jo F. Chung; Andrea G. Fabbri; Dong-Ho Jang

345

Modeling and estimating the spatial distribution of healthcare workers  

Microsoft Academic Search

This paper describes a spatial model for healthcare workers' location in a large hospital facility. Such models have many applications in healthcare, such as supporting time-and- motion efficiency studies to improve healthcare delivery, or modeling the spread of hospital-acquired infections. We use our model to estimate spatial distributions for healthcare workers in The University of Iowa Hospitals and Clinics (UIHC),

Donald Ephraim Curtis; Christopher S. Hlady; Sriram V. Pemmaraju; Philip M. Polgreen; Alberto Maria Segre

2010-01-01

346

Uncertain spatial data handling: Modeling, indexing and query  

Microsoft Academic Search

Managing and manipulating uncertainty in spatial databases are important problems for various practical applications of geographic information systems. Unlike the traditional fuzzy approaches in relational databases, in this paper a probability-based method to model and index uncertain spatial data is proposed. In this scheme, each object is represented by a probability density function (PDF) and a general measure is proposed

Rui Li; Bir Bhanu; Chinya Ravishankar; Michael Kurth; Jinfeng Ni

2007-01-01

347

Fine-pitch MOEMS packaging for novel Spatial Light Modulator  

Microsoft Academic Search

A novel SLM (spatial light modulator), named SOM (spatial optical modulator) has been developed. SOM is one dimensional mirror array device, so the pixel number and the dimension of the mirror array could be easily designed for application specific. Full-HD rear projection displays with 1080-pixel SOM devices and VGA resolution embedded mobile projection displays with 480-pixel SOM devices have been

Heung Woo Park; Yeong Gyu Lee; Chang Su Park; Ohk Kun Lim; Dong Hyun Park; Seok Kee Hong; Young Nam Hwang; Jong Hyeong Song; Yun Joon Choi; Sang Kyeong Yun

2008-01-01

348

Response Surface Methods for Spatially-Resolved Optical Measurement Techniques.  

National Technical Information Service (NTIS)

Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatial ly-re solved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, a...

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

2003-01-01

349

Spatial Data Methods and Vague Regions: A Rough Set Approach.  

National Technical Information Service (NTIS)

Uncertainty management has been considered essential for real world applications, and spatial data and geographic information systems in particular require some means for managing uncertainty and vagueness. Rough sets have been shown to be an effective to...

F. E. Petry R. Ladner T. Beaubouef

2003-01-01

350

Spatially-Varying IIR Filter Banks for Image Coding.  

National Technical Information Service (NTIS)

This paper reports on the application of spatially variant infinite impulse response (IIR) filter banks to subband image coding. The new filter bank is based on computationally efficient recursive polyphase decompositions that dynamically change in respon...

W. C. Chung M. J. T. Smith

1992-01-01

351

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...

352

Dealing with spatial heterogeneity  

NASA Astrophysics Data System (ADS)

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 faciès fins de barrières de perméabilité, qui ont une influence importante sur les écoulement, et, plus encore, sur le transport. Les modè les génétiques récemment apparus ont la capacité de mieux incorporer dans les modèles de faciès les observations géologiques, chose courante dans l'industrie pétrolière, mais insuffisamment développée en hydrogéologie. On conclut que les travaux de recherche ultérieurs devraient s'attacher à développer les modèles de faciès, à les comparer entre eux, et à mettre au point de nouvelles méthodes d'essais in situ, comprenant les méthodes géophysiques, capables de reconnaître la géométrie et les propriétés des faciès. La constitution d'un catalogue mondial de la géométrie et des propriétés des faciès aquifères, ainsi que des méthodes de reconnaissance utilisées pour arriver à la détermination de ces systèmes, serait d'une grande importance pratique pour les applications. La heterogeneidad se puede manejar por medio de la definición de características homogéneas equivalentes, conocidas como promediar o tratando de describir la variabilidad espacial de las características de las rocas a partir de observaciones geológicas y medidas locales. Las técnicas disponibles para estas descripciones son generalmente modelos geoestadísticos continuos o modelos de facies discontinuos como los modelos Boolean, de Indicador o de umbral de Gaussian y el modelo de cadena de Markow. Estos modelos de facies son mas adecuados para tratar la conectvidad de estratos geológicos (por ejemplo canales de alta permeabilidad enterrados o barreras de baja permeabilidad que tienen efectos importantes sobre el flujo y especialmente sobre el transporte en los acuíferos. Los modelos genéticos ofrecen nuevas formas de incorporar más geología en las descripciones de facies, un enfoque que está bien desarollado en la industria petrolera, pero insuficientemente en la hidrogeología. Se concluye que los trabajos futuros deberían estar más enfocados en mejorar los modelos de facies, en establecer comparaciones y en

Marsily, Gh.; Delay, F.; Gonçalvès, J.; Renard, Ph.; Teles, V.; Violette, S.

2005-03-01

353

Spatial data integration and analysis with spatial intelligence  

Microsoft Academic Search

More and more researchers from different fields find it essential to combine GIS data to do survey data analysis and multi-disciplinary studies. Spatial intelligence allows efficient data integration for spatial and non-spatial data, quick and accurate location analysis and spatial assessment. In this paper, we present an updated version of China Geo-Explorer, a web based platform for spatial intelligence, which

Bing She; Xinyan Zhu; Shuming Bao

2010-01-01

354

Spatial strategies for managing visitor impacts in National Parks  

USGS Publications Warehouse

Resource and social impacts caused by recreationists and tourists have become a management concern in national parks and equivalent protected areas. The need to contain visitor impacts within acceptable limits has prompted park and protected area managers to implement a wide variety of strategies and actions, many of which are spatial in nature. This paper classifies and illustrates the basic spatial strategies for managing visitor impacts in parks and protected areas. A typology of four spatial strategies was proposed based on the recreation and park management literature. Spatial segregation is a common strategy for shielding sensitive resources from visitor impacts or for separating potentially conflicting types of use. Two forms of spatial segregation are zoning and closure. A spatial containment strategy is intended to minimize the aggregate extent of visitor impacts by confining use to limited designated or established Iocations. In contrast, a spatial dispersal strategy seeks to spread visitor use, reducing the frequency of use to levels that avoid or minimize permanent resource impacts or visitor crowding and conflict. Finally, a spatial configuration strategy minimizes impacting visitor behavior though the judicious spatial arrangement of facilities. These four spatial strategics can be implemented separately or in combination at varying spatial scales within a single park. A survey of national park managers provides an empirical example of the diversity of implemented spatial strategies in managing visitor impacts. Spatial segregation is frequently applied in the form of camping restrictions or closures to protect sensitive natural or cultural resources and to separate incompatible visitor activities. Spatial containment is the most widely applied strategy for minimizing the areal extent of resource impacts. Spatial dispersal is commonly applied to reduce visitor crowding or conflicts in popular destination areas but is less frequently applied or 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.

Leung, Y.F.; Marion, J.L.

1999-01-01

355

Reconstructing Spatial Distributions from Anonymized Locations  

SciTech Connect

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.

Horey, James L [ORNL; Forrest, Stephanie [University of New Mexico, Albuquerque; Groat, Michael [University of New Mexico, Albuquerque

2012-01-01

356

Numerical modeling of spatial coherence using the elementary function method.  

PubMed

The elementary function method is an approximate method for propagation calculations in spatially, partially coherent light in two dimensions. In this paper, we present the numerical application of this method to a 248 nm UV excimer laser source. We present experimental results of the measurement of the degree of spatial coherence and the beam profile of this source. The elementary function method is then applied to the real beam data and used to simulate the effects of imaging an opaque edge with a source of varying degrees of spatial coherence. The effect of spatial coherence on beam homogenization is also presented. PMID:23669693

Smith, Arlene; Dainty, Christopher

2013-04-20

357

Iterative design of pupil functions for bipolar incoherent spatial filtering  

NASA Astrophysics Data System (ADS)

An iterative algorithm is described for the computer generation of complementary pupil functions to be used in hybrid incoherent optical systems for bipolar spatial filtering. Through repeated transformations between the Fourier and spatial domains, and the application of constraints in both, the pupil functions are constructed subject to the ultimate constraint that the difference of the associated PSFs result in a desired bipolar spatial impulse response. Minimization of component PSF bias is a major concern. The case of bandpass spatial filtering will be discussed in detail and preliminary results presented.

Mait, J. N.; Rhodes, W. T.

1981-01-01

358

Perceptual categories for spatial layout.  

PubMed Central

The central problems of vision are often divided into object identification and localization. Object identification, at least at fine levels of discrimination, may require the application of top-down knowledge to resolve ambiguous image information. Utilizing top-down knowledge, however, may require the initial rapid access of abstract object categories based on low-level image cues. Does object localization require a different set of operating principles than object identification or is category determination also part of the perception of depth and spatial layout? Three-dimensional graphics movies of objects and their cast shadows are used to argue that identifying perceptual categories is important for determining the relative depths of objects. Processes that can identify the causal class (e.g. the kind of material) that generates the image data can provide information to determine the spatial relationships between surfaces. Changes in the blurriness of an edge may be characteristically associated with shadows caused by relative motion between two surfaces. The early identification of abstract events such as moving object/shadow pairs may also be important for depth from shadows. Knowledge of how correlated motion in the image relates to an object and its shadow may provide a reliable cue to access such event categories.

Kersten, D

1997-01-01

359

The Impact of Spatial Scales and Spatial Smoothing on the Outcome of Bayesian Spatial Model  

PubMed Central

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.

Kang, Su Yun; McGree, James; Mengersen, Kerrie

2013-01-01

360

Hierarchical Modeling for Spatial Data Problems  

PubMed Central

This short paper is centered on hierarchical modeling for problems in spatial and spatio-temporal statistics. It draws its motivation from the interdisciplinary research work of the author in terms of applications in the environmental sciences - ecological processes, environmental exposure, and weather modeling. The paper briefly reviews hierarchical modeling specification, adopting a Bayesian perspective with full inference and associated uncertainty within the specification, while achieving exact inference to avoid what may be uncomfortable asymptotics. It focuses on point-referenced (geo-statistical) and point pattern spatial settings. It looks in some detail at problems involving data fusion, species distributions, and large spatial datasets. It also briefly describes four further examples arising from the author's recent research projects.

Gelfand, Alan E.

2013-01-01

361

Bayesian Spatial Quantile Regression  

PubMed Central

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.

Reich, Brian J.; Fuentes, Montserrat; Dunson, David B.

2013-01-01

362

Bayesian Spatial Quantile Regression.  

PubMed

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

Reich, Brian J; Fuentes, Montserrat; Dunson, David B

2012-01-01

363

CREATING SPATIAL ORGANIZATIONS  

Microsoft Academic Search

This paper addresses the spatial design of modern organizations in the context of a fundamental change which is currently taking place in the way companies view their organizations and the inherent performance expectations, requirements and results underlying these. This change involves a managerial shift in perspective from the commonly adopted resource-based view of the firm, towards the knowledge based view

Frank Lekanne Deprez; René Tissen

2009-01-01

364

Chunking in Spatial Memory  

ERIC Educational Resources Information Center

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…

Sargent, Jesse; Dopkins, Stephen; Philbeck, John; Chichka, David

2010-01-01

365

Handbook of Spatial Cognition  

ERIC Educational Resources Information Center

|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…

Waller, David, Ed.; Nadel, Lynn, Ed.

2012-01-01

366

Spatially homothetic cosmological models  

Microsoft Academic Search

Spatially homothetic cosmological models are defined as space-time manifolds acted on by a 3-parameter group of transformations transitive over spacelike hypersurfaces, whose effect is to multiply the metric by a constant conformal factor. Previous work on these models is reviewed briefly and the algebraic classification scheme of Eardley is described. Explicit forms of the metric and group generators are given

J. P. Luminet

1978-01-01

367

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...

368

Spatial analysis for epidemiology  

Microsoft Academic Search

Remote sensing, geographical information systems (GIS) and spatial analysis provide important tools that are as yet under-exploited in the fight against disease. As the use of such tools becomes more accepted and prevalent in epidemiological studies, so our understanding of the mechanisms of disease systems has the potential to increase. This paper introduces a range of techniques used in remote

A. J Graham; P. M Atkinson; F. M Danson

2004-01-01

369

Spatialities of globalisation  

Microsoft Academic Search

The focus of this paper is on the theorisation of the spatialities of globalisation. I seek to shift the emphasis away from the currently dominant discourse of scalar and territorial relativisation, towards relational processes and network forms of organisation that defy a linear distinction between place and space. I stress the importance of actor networks of varying length and duration

Ash Amin

2002-01-01

370

Handbook of Spatial Cognition  

ERIC Educational Resources Information Center

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…

Waller, David, Ed.; Nadel, Lynn, Ed.

2012-01-01

371

Spatial storm statistics  

NASA Astrophysics Data System (ADS)

The classical approach to storm statistics in the ocean is an Eulerian analysis of wave time series at a given location, in which the wave data can be observations or results of wave models. The information obtained from this approach is storm frequency, duration and intensity, from which extremes only at the particular location can be estimated. The availability of spatial information of wave characteristics at successive time intervals, which is available from large scale hindcast allows the follow-up of storm evolution in space and time. Using this data it is possible to study the spatial evolution of storms, i.e. to provide a Lagrangean description of storm characteristics. Ships cross the ocean in the routes that are chosen in order to minimize danger and expenses. A safer route will try to avoid high seas and areas with high probability of storms. In the Eulerian approach information about the storm spatial and temporal evolution is not available. In the Lagrangean approach a storm is defined as spatial pulse above the defined threshold z, which is moving over the basin. The area defined by the set of contiguous points is the storm area in any moment. It is possible to obtain the geometrical center of the storm, it square, speed of movement, the maximum significant wave heights (SWH), the coordinates of the maximum SWH values, and some other statistics. The details of approaches and results for some Seas and N. Atlantic will be presented.

Lopatoukhin, Leonid; Boukhanovsky, Alexander; Chernysheva, Ekaterina

2013-04-01

372

Spatial and Velocity Biases  

Microsoft Academic Search

We give a summary of our recent studies of spatial and velocity biases of galaxy-size halos in cosmological models. Recent progress in numerical techniques made it possible to simulate halos in large volumes with a such accuracy that halos survive in dense environments of groups and clusters of galaxies. Dark matter halos in simulations look like real galaxies, and, thus,

A. Klypin; A. Kravtsov; P. Colín

2000-01-01

373

Spatial cluster detection using dynamic programming  

PubMed Central

Background The task of spatial cluster detection involves finding spatial regions where some property deviates from the norm or the expected value. In a probabilistic setting this task can be expressed as finding a region where some event is significantly more likely than usual. Spatial cluster detection is of interest in fields such as biosurveillance, mining of astronomical data, military surveillance, and analysis of fMRI images. In almost all such applications we are interested both in the question of whether a cluster exists in the data, and if it exists, we are interested in finding the most accurate characterization of the cluster. Methods We present a general dynamic programming algorithm for grid-based spatial cluster detection. The algorithm can be used for both Bayesian maximum a-posteriori (MAP) estimation of the most likely spatial distribution of clusters and Bayesian model averaging over a large space of spatial cluster distributions to compute the posterior probability of an unusual spatial clustering. The algorithm is explained and evaluated in the context of a biosurveillance application, specifically the detection and identification of Influenza outbreaks based on emergency department visits. A relatively simple underlying model is constructed for the purpose of evaluating the algorithm, and the algorithm is evaluated using the model and semi-synthetic test data. Results When compared to baseline methods, tests indicate that the new algorithm can improve MAP estimates under certain conditions: the greedy algorithm we compared our method to was found to be more sensitive to smaller outbreaks, while as the size of the outbreaks increases, in terms of area affected and proportion of individuals affected, our method overtakes the greedy algorithm in spatial precision and recall. The new algorithm performs on-par with baseline methods in the task of Bayesian model averaging. Conclusions We conclude that the dynamic programming algorithm performs on-par with other available methods for spatial cluster detection and point to its low computational cost and extendability as advantages in favor of further research and use of the algorithm.

2012-01-01

374

Spatial symmetry breaking in rapidly rotating convective spherical shells  

NASA Astrophysics Data System (ADS)

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.

Zhang, Keke; Schubert, Gerald

1995-05-01

375

High Spatial Resolution Remotely Sensed Data for Ecosystem Characterization  

NSDL National Science Digital Library

This peer-reviewed resource from Bioscience magazine presents technical aspects of remote sensing for images at high spatial resolution. Characterization of ecosystem structure, diversity, and function is increasingly desired at finer spatial and temporal scales than have been derived in the past. Many ecological applications require detailed data representing large spatial extents, but these data are often unavailable or are impractical to gather using field-based techniques. Remote sensing offers an option for collecting data that can represent broad spatial extents with detailed attribute characterizations. Remotely sensed data are also appropriate for use in studies across spatial scales, in conjunction with field-collected data. This article presents the pertinent technical aspects of remote sensing for images at high spatial resolution (i.e., with a pixel size of 16 square meters or less), existing and future options for the processing and analysis of remotely sensed data, and attributes that can be estimated with these data for forest ecosystems.

MICHAEL A. WULDER, RONALD J. HALL, NICHOLAS C. COOPS, and STEVEN E. FRANKLIN (;)

2004-06-01

376

Spatial analysis of hemorrhagic fever with renal syndrome in China  

PubMed Central

Background Hemorrhagic fever with renal syndrome (HFRS) is endemic in many provinces with high incidence in mainland China, although integrated intervention measures including rodent control, environment management and vaccination have been implemented for over ten years. In this study, we conducted a geographic information system (GIS)-based spatial analysis on distribution of HFRS cases for the whole country with an objective to inform priority areas for public health planning and resource allocation. Methods Annualized average incidence at a county level was calculated using HFRS cases reported during 1994–1998 in mainland China. GIS-based spatial analyses were conducted to detect spatial autocorrelation and clusters of HFRS incidence at the county level throughout the country. Results Spatial distribution of HFRS cases in mainland China from 1994 to 1998 was mapped at county level in the aspects of crude incidence, excess hazard and spatial smoothed incidence. The spatial distribution of HFRS cases was nonrandom and clustered with a Moran's I = 0.5044 (p = 0.001). Spatial cluster analyses suggested that 26 and 39 areas were at increased risks of HFRS (p < 0.01) with maximum spatial cluster sizes of ? 20% and ? 10% of the total population, respectively. Conclusion The application of GIS, together with spatial statistical techniques, provide a means to quantify explicit HFRS risks and to further identify environmental factors responsible for the increasing disease risks. We demonstrate a new perspective of integrating such spatial analysis tools into the epidemiologic study and risk assessment of HFRS.

Fang, Liqun; Yan, Lei; Liang, Song; de Vlas, Sake J; Feng, Dan; Han, Xiaona; Zhao, Wenjuan; Xu, Bing; Bian, Ling; Yang, Hong; Gong, Peng; Richardus, Jan Hendrik; Cao, Wuchun

2006-01-01

377

Modeling spatial variation in avian survival and residency probabilities.  

PubMed

The importance of understanding spatial variation in processes driving animal population dynamics is widely recognized. Yet little attention has been paid to spatial modeling of vital rates. Here we describe a hierarchical spatial autoregressive model to provide spatially explicit year-specific estimates of apparent survival (phi) and residency (pi) probabilities from capture-recapture data. We apply the model to data collected on a declining bird species, Wood Thrush (Hylocichla mustelina), as part of a broad-scale bird-banding network, the Monitoring Avian Productivity and Survivorship (MAPS) program. The Wood Thrush analysis showed variability in both phi and pi among years and across space. Spatial heterogeneity in residency probability was particularly striking, suggesting the importance of understanding the role of transients in local populations. We found broad-scale spatial patterning in Wood Thrush phi and pi that lend insight into population trends and can direct conservation and research. The spatial model developed here represents a significant advance over approaches to investigating spatial pattern in vital rates that aggregate data at coarse spatial scales and do not explicitly incorporate spatial information in the model. Further development and application of hierarchical capture-recapture models offers the opportunity to more fully investigate spatiotemporal variation in the processes that drive population changes. PMID:20715606

Saracco, James F; Royle, J Andrew; DeSante, David F; Gardner, Beth

2010-07-01

378

Modeling spatial variation in avian survival and residency probabilities  

USGS Publications Warehouse

The importance of understanding spatial variation in processes driving animal population dynamics is widely recognized. Yet little attention has been paid to spatial modeling of vital rates. Here we describe a hierarchical spatial autoregressive model to provide spatially explicit year-specific estimates of apparent survival (phi) and residency (pi) probabilities from capture-recapture data. We apply the model to data collected on a declining bird species, Wood Thrush (Hylocichla mustelina), as part of a broad-scale bird-banding network, the Monitoring Avian Productivity and Survivorship (MAPS) program. The Wood Thrush analysis showed variability in both phi and pi among years and across space. Spatial heterogeneity in residency probability was particularly striking, suggesting the importance of understanding the role of transients in local populations. We found broad-scale spatial patterning in Wood Thrush phi and pi that lend insight into population trends and can direct conservation and research. The spatial model developed here represents a significant advance over approaches to investigating spatial pattern in vital rates that aggregate data at coarse spatial scales and do not explicitly incorporate spatial information in the model. Further development and application of hierarchical capture-recapture models offers the opportunity to more fully investigate spatiotemporal variation in the processes that drive population changes.

Saracco, James F.; Royle, J. Andrew; DeSante, David F.; Gardner, Beth

2010-01-01

379

Optimization techniques for integrating spatial data  

USGS Publications Warehouse

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.

Herzfeld, U. C.; Merriam, D. F.

1995-01-01

380

Logo detection based on spatial-spectral saliency and partial spatial context  

Microsoft Academic Search

Logo detection is important for brand advertising and surveillance applications. The central issues of this technology are fast localization and accurate matching. Based on key traits analysis of common logos, this paper presents a two-stage detection scheme based on spatialspectral saliency (SSS) and partial spatial context (PSC). SSS speeds up logo location and avoid the impact of cluttered background. PSC

Ke Gao; Shouxun Lin; Yongdong Zhang; Sheng Tang; Dongming Zhang

2009-01-01

381

Regional convergence in the European Union (1985-1999). A spatial dynamic panel analysis  

Microsoft Academic Search

We estimate the speed of income convergence for a sample of 196 European NUTS 2 regions over the period 1985-1999. So far there is no direct estimator available for dynamic panels with strong spatial dependencies. We propose a two-step procedure, which involves first spatial filtering of the variables to remove the spatial correlation, and application of standard GMM estimators for

Gabriele Tondl; Werner Müller

2003-01-01

382

Decision tree classification of spatial data streams using Peano Count Trees  

Microsoft Academic Search

Many organizations have large quantities of spatial data collected in various application areas, including remote sensing, geographical information systems (GIS), astronomy, computer cartography, environmental assessment and planning, etc. These data collections are growing rapidly and can therefore be considered as spatial data streams. For data stream classification, time is a major issue. However, these spatial data sets are too large

Qiang Ding; Qin Ding; William Perrizo

2002-01-01

383

Model Validation in Spatial Econometrics: A Review and Evaluation of Alternative Approaches  

Microsoft Academic Search

Formal approaches to assess the validity of spatial theoretical constructs are reviewed and evaluated with respect to their application and potential in spatial econometrics. A distinction is made between specification tests and model selection procedures. For the first, particular emphasis is on tests for residual spatial autocorrelation, tests on common factors, and tests on non-nested hypotheses. For the second, attention

Luc Anselin

1988-01-01

384

SEE: A Spatial Exploration Environment Based on a Direct-Manipulation Paradigm  

Microsoft Academic Search

The need to provide effective tools for analyzing and querying spatial data is becoming increasingly important with the explosion of data in applications such as geographic information systems, image databases, CAD, and remote sensing. The SEE (Spatial Exploration Environment) is the first effort at applying direct-manipulation visual information seeking (VIS) techniques to spatial data analysis by visually querying as well

Sudhir R. Kaushik; Elke A. Rundensteiner

2001-01-01

385

A Spatial Econometric Approach to the Economics of Site-Specific Nitrogen Management in Corn Production  

Microsoft Academic Search

The objective of this study is to determine the potential for using spatial econometric analysis of combine yield monitor data to estimate the site-specific crop response functions. The specific case study is for site-specific nitrogen (N) application to corn production in Argentina. Spatial structure of the yield data is modeled with landscape variables, spatially autoregressive error and groupwise heteroskedasticity. Results

Luc Anselin; Rodolfo Bongiovanni; Jess Lowenberg-DeBoer

2004-01-01

386

Microchannel spatial light modulator  

NASA Astrophysics Data System (ADS)

The Microchannel Spatial Light Modulator (MSLM), a versatile, highly sensitive, and optically addressed device being developed for real time optical information processing is discussed. The MSLM operates by converting an input optical image into a charge distribution at the surface of an electro-optic crystal. The charge distribution generates an electric field which modulates the refractive index of the crystal and thereby the phase or intensity of an image readout beam. Prototype devices employing 250 micron thick crystals exhibited a spatial resolution of 5 cycles/mm at 50% contrast, an exposure sensitivity of 2.2 nJ/cu cm and framing rates of 40 Hz with full modulation depth. The image processing operations that have been achieved using the internal processing mode of the MSLM include contrast reversal, contrast enhancement, edge enhancement, image addition and subtraction, analog and digital intensity thresholding, and binary level logic operations such as AND, OR, EXCLUSIVE OR, and NOR.

Warde, C.

1981-12-01

387

Asymmetric spatial soliton dragging.  

PubMed

A new low-latency, cascadable optical logic gate with gain, high contrast, and three-terminal input-output isolation is introduced. The interaction between two orthogonally polarized spatial solitons brought into coincidence at the boundary of a saturating nonlinear medium and propagating in different directions results in the phase-insensitive spatial dragging of a strong pump soliton by a weaker signal. As a result, the strong pump is transmitted through an aperture when the weak signal is not present, and it is dragged to the side by more than a beam width and blocked in the presence of the weak signal, thus implementing an inverter with gain. A multi-input, logically complete NOR gate also can be implemented in a cascaded system. PMID:19855703

Blair, S; Wagner, K; McLeod, R

1994-12-01

388

Spatial models with spatially lagged dependent variables and incomplete data  

Microsoft Academic Search

The purpose of this paper is to suggest estimators for the parameters of spatial models containing a spatially lagged dependent variable, as well as spatially lagged independent variables, and an incomplete data set. The specifications allow for nonstationarity, and the disturbance process of the model is specified non-parametrically. We consider various scenarios concerning the pattern of missing data points. One

Harry H. Kelejian; Ingmar R. Prucha

2010-01-01

389

Spatial Data Analysis  

NASA Astrophysics Data System (ADS)

Are there geographic clusters of disease cases, or hotspots of crime? Can the geography of air quality be matched to where people hospitalized for respiratory complaints actually live? Spatial data is data about the world where the attribute of interest and its location on the earth's surface are recorded. This comprehensive overview of the subject shows how the above questions can be tackled. It is written for students and researchers in geography, economics, social science, the environmental sciences and statistics.

Haining, Robert

2003-06-01

390

Spatial control of exocytosis  

PubMed Central

During many key biological processes, exocytosis is confined to distinct regions of the plasma membrane. Spatial control of exocytosis correlates with altered membrane skeleton dynamics and assembly of local membrane microdomains. These domains act as local stages for the assembly and the regulation of molecular complexes (targeting patches) that mediate vesicle–membrane fusion. Furthermore, local activation of signaling pathways reinforces formation of these patches and might effect global repositioning of the secretory pathway toward sites of localized exocytosis.

Spiliotis, Elias T.; Nelson, W. James

2012-01-01

391

Spatial and Velocity Biases  

Microsoft Academic Search

We give a summary of our recent studies of spatial and velocity biases of\\u000agalaxy-size halos in cosmological models. Recent progress in numerical\\u000atechniques made it possible to simulate halos in large volumes with a such\\u000aaccuracy that halos survive in dense environments of groups and clusters of\\u000agalaxies. Dark matter halos in simulations look like real galaxies, and, thus,

Anatoly Klypin; Andrey V. Kravtsov; Pedro Colin

1999-01-01

392

Geometry and Spatial Relations: Sidewalk Capers  

NSDL National Science Digital Library

In this 28-minute professional development video, teachers focus on geometry and spatial relations by having students explore shapes that tessellate and have the same area. Teachers from different grade levels collaborate on what they want their students to be able to understand and accomplish. Viewers can watch how a 3rd-grade teacher guides his students in understanding area through the application of tessellations. Support Materials includes a Sidewalk Capers Lesson Plan.

Mathline; Portis, Chris

1997-01-01

393

Spatial Resolution in Industrial Tomography.  

National Technical Information Service (NTIS)

Results are presented of research undertaken to investigate the parametric dependence of spatial resolution attainable in a tomographic examination. Research was performed on a specially fabricated object, a spatial resolution phantom. Parameters such as ...

1982-01-01

394

Hierarchical Spatial Modeling of Additive and Dominance Genetic Variance for Large Spatial Trial Datasets  

PubMed Central

Summary This article expands upon recent interest in Bayesian hierarchical models in quantitative genetics by developing spatial process models for inference on additive and dominance genetic variance within the context of large spatially referenced trial datasets. Direct application of such models to large spatial datasets are, however, computationally infeasible because of cubic-order matrix algorithms involved in estimation. The situation is even worse in Markov chain Monte Carlo (MCMC) contexts where such computations are performed for several iterations. Here, we discuss approaches that help obviate these hurdles without sacrificing the richness in modeling. For genetic effects, we demonstrate how an initial spectral decomposition of the relationship matrices negate the expensive matrix inversions required in previously proposed MCMC methods. For spatial effects, we outline two approaches for circumventing the prohibitively expensive matrix decompositions: the first leverages analytical results from Ornstein–Uhlenbeck processes that yield computationally efficient tridiagonal structures, whereas the second derives a modified predictive process model from the original model by projecting its realizations to a lower-dimensional subspace, thereby reducing the computational burden. We illustrate the proposed methods using a synthetic dataset with additive, dominance, genetic effects and anisotropic spatial residuals, and a large dataset from a Scots pine (Pinus sylvestris L.) progeny study conducted in northern Sweden. Our approaches enable us to provide a comprehensive analysis of this large trial, which amply demonstrates that, in addition to violating basic assumptions of the linear model, ignoring spatial effects can result in downwardly biased measures of heritability.

Finley, Andrew O.; Banerjee, Sudipto; Waldmann, Patrik; Ericsson, Tore

2009-01-01

395

Spatial Representation with Aspect Maps  

Microsoft Academic Search

This paper describes the aspect map approach to model the processing of geographic maps. Geographic maps are described as spatial representation media which play an important role in many processes of human spatial cognition. We focus on the aspectuality of representation and therefore deal with aspect maps: spatial organization structures in which one or more aspects of geographic entities are

Bettina Berendt; Thomas Barkowsky; Christian Freksa; Stephanie Kelter

1998-01-01

396

Distance browsing in spatial databases  

Microsoft Academic Search

We compare two different techniques for browsing through a collection of spatial objects stored in an R-tree spatial data structure on the basis of their distances from an arbitrary spatial query object. The conventional approach is one that makes use of a k-nearest neighbor algorithm where k is known prior to the invocation of the algorithm. Thus if m k

Gísli R. Hjaltason; Hanan Samet

1999-01-01

397

Cokriging for spatial functional data  

Microsoft Academic Search

This work proposes to generalize the method of kriging when data are spatially sampled curves. A spatial functional linear model is constructed including spatial dependencies between curves. Under some regularity conditions of the curves, an ordinary kriging system is established in the infinite dimensional case. From a practical point-of-view, the decomposition of the curves into a functional basis boils down

David Nerini; Pascal Monestiez; Claude Manté

2010-01-01

398

Spatial Distribution of Retail Sales  

Microsoft Academic Search

We examine the distribution of sales for a retail chain in the Houston market using a spatial gravity model. Unlike previous empirical studies, our approach models spatial dependencies among both consumers and retailers. The results show that both forms of spatial dependence exert statistically and economically significant impacts on the estimates of parameters in retail gravity models. Contrary to the

Ming-Long Lee; R. Kelley Pace

2005-01-01

399

Contour Integration across Spatial Frequency  

ERIC Educational Resources Information Center

|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.…

Persike, Malte; Olzak, Lynn A.; Meinhardt, Gunter

2009-01-01

400

Detecting Spatial Outliers with Multiple Attributes  

Microsoft Academic Search

A spatial outlier is a spatially referenced object whose non-spatial attribute values are significantly different from the values of its neighborhood. Identification of spatial outliers can lead to the discovery of unexpected, interesting, and useful spatial patterns for further analysis. Previous work in spatial outlier detection focuses on detecting spatial outliers with a single attribute. In the paper, we propose

Chang-tien Lu; Dechang Chen; Yufeng Kou

2003-01-01

401

Testing for spatial association of qualitative data using symbolic dynamics  

NASA Astrophysics Data System (ADS)

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.

Ruiz, Manuel; López, Fernando; Páez, Antonio

2010-09-01

402

Chemistry with spatial control using particles and streams().  

PubMed

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

Kalinin, Yevgeniy V; Murali, Adithya; Gracias, David H

2012-10-28

403

Chemistry with spatial control using particles and streams†  

PubMed Central

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.

Kalinin, Yevgeniy V.; Murali, Adithya

2012-01-01

404

Extinction and the spatial dynamics of biodiversity  

PubMed Central

The fossil record amply shows that the spatial fabric of extinction has profoundly shaped the biosphere; this spatial dimension provides a powerful context for integration of paleontological and neontological approaches. Mass extinctions evidently alter extinction selectivity, with many factors losing effectiveness except for a positive relation between survivorship and geographic range at the clade level (confirmed in reanalyses of end-Cretaceous extinction data). This relation probably also holds during “normal” times, but changes both slope and intercept with increasing extinction. The strong geographical component to clade dynamics can obscure causation in the extinction of a feature or a clade, owing to hitchhiking effects on geographic range, so that multifactorial analyses are needed. Some extinctions are spatially complex, and regional extinctions might either reset a diversity ceiling or create a diversification debt open to further diversification or invasion. Evolutionary recoveries also exhibit spatial dynamics, including regional differences in invasibilty, and expansion of clades from the tropics fuels at least some recoveries, as well as biodiversity dynamics during normal times. Incumbency effects apparently correlate more closely with extinction intensities than with standing diversities, so that regions with higher local and global extinctions are more subject to invasion; the latest Cenozoic temperate zones evidently received more invaders than the tropics or poles, but this dynamic could shift dramatically if tropical diversity is strongly depleted. The fossil record can provide valuable insights, and their application to present-day issues will be enhanced by partitioning past and present-day extinctions by driving mechanism rather than emphasizing intensity.

Jablonski, David

2008-01-01

405

Anatomical Global Spatial Normalization  

PubMed Central

Anatomical global spatial normalization (aGSN) is presented as a method to scale high-resolution brain images to control for variability in brain size without altering the mean size of other brain structures. Two types of mean preserving scaling methods were investigated, “shape preserving” and “shape standardizing”. aGSN was tested by examining 56 brain structures from an adult brain atlas of 40 individuals (LPBA40) before and after normalization, with detailed analyses of cerebral hemispheres, all gyri collectively, cerebellum, brainstem, and left and right caudate, putamen, and hippocampus. Mean sizes of brain structures as measured by volume, distance, and area were preserved and variance reduced for both types of scale factors. An interesting finding was that scale factors derived from each of the ten brain structures were also mean preserving. However, variance was best reduced using whole brain hemispheres as the reference structure, and this reduction was related to its high average correlation with other brain structures. The fractional reduction in variance of structure volumes was directly related to ?2, the square of the reference-to-structure correlation coefficient. The average reduction in variance in volumes by aGSN with whole brain hemispheres as the reference structure was approximately 32%. An analytical method was provided to directly convert between conventional and aGSN scale factors to support adaptation of aGSN to popular spatial normalization software packages.

Cykowski, Matthew D.; McKay, David Reese; Kochunov, Peter V.; Fox, Peter T.; Rogers, William; Toga, Arthur W.; Zilles, Karl; Amunts, Katrin; Mazziotta, John

2010-01-01

406

PARM - An Efficient Algorithm to Mine Association Rules From Spatial Data  

Microsoft Academic Search

Association rule mining, originally proposed for market basket data, has potential applications in many areas. Spatial data, such as remote sensed imagery (RSI) data, is one of the promising application areas. Extracting interesting patterns and rules from spatial data sets, composed of images and associated ground data, can be of importance in precision agriculture, resource discovery, and other areas. However,

Qin Ding; Qiang Ding; William Perrizo

2008-01-01

407

A binaural auditory model for sound quality measurements and spatial hearing studies  

Microsoft Academic Search

This paper addresses auditory modeling in relation to binaural applications. Relatively few studies so far exist where auditory modeling is extended to include advanced binaural features. There are numerous potential applications where such modeling may yield practical results or improved insight into the problem. The focus is to develop models for spatial sound quality measurements and general modeling of spatial

M. Karajalainen

1996-01-01

408

Application of XAD-2 resin-based passive samplers and SPME-GC-MS/MS analysis for the monitoring of spatial and temporal variations of atmospheric pesticides in Luxembourg.  

PubMed

Passive air sampling has been shown to be a very interesting alternative to high-volume sampling by overcoming its disadvantages (size, weight, expensiveness). However, to date, only limited data is available about passive air sampling of current-use pesticides. In order to test if passive samplers allow monitoring of spatial and temporal variations of atmospheric pesticide concentrations, five XAD-2-resin based passive air samplers were deployed at five locations in Luxembourg. Samplers were analyzed using accelerated solvent extraction coupled to solid-phase microextraction and gas chromatography with tandem mass spectrometry. Collected data was used to study the spatial and temporal variations of the concentrations of the compounds. Twenty two pesticides were detected between March and October, while no pesticides were detected from November to February. Highest concentrations were measured on the rural sites, suggesting that the used XAD-2 resin-based passive samplers allow the simultaneous monitoring of multiple current-use pesticides and identifying spatial and temporal variations. PMID:22771355

Schummer, Claude; Tuduri, Ludovic; Briand, Olivier; Appenzeller, Brice M; Millet, Maurice

2012-07-05

409

High-performance spatial indexing for location-based services  

Microsoft Academic Search

Much attention has been accorded to Location-Based Services and location tracking, a necessary component in active, trigger-based LBS applications. Tracking the location of a large population of moving objects requires very high update and query performance of the underlying spatial index. In this paper we investigate the performance and scalability of three main-memory based spatial indexing methods under dynamic update

Jussi Myllymaki; James H. Kaufman

2003-01-01

410

A spatial method for integrating data of different types  

Microsoft Academic Search

Systematically recording archaeological, historical, ethnographic, and other information in a geographical-temporal frame\\u000a has great advantages. The method allows the logical ordering of disparate facts, error checking, making connections that might\\u000a otherwise go undetected, better comparison, manipulating temporal and spatial scales, and specifying the fields within which\\u000a causal processes do and do not operate. The application of this spatial method in

Stephen A. Kowalewski

1997-01-01

411

Nuclear waste repository characterization: a spatial estimation/identification approach  

SciTech Connect

This paper considers the application of spatial estimation techniques to a groundwater aquifer and geological borehole data. It investigates the adequacy of these techniques to reliably develop contour maps from various data sets. The practice of spatial estimation is discussed and the estimator is then applied to a groundwater aquifer system and a deep geological formation. It is shown that the various statistical models must first be identified from the data and evaluated before reasonable results can be expected.

Candy, J.V.; Mao, N.

1981-03-01

412

Web-based Spatial Decision Support: Status and Research Directions  

Microsoft Academic Search

This paper summarizes research on Web-based spatial decision support systems (WebSDSS). The review distinguishes early server-side from more recent client-side applications. A third category of WebSDSS focusing on spatial decision support in public participation is typically implemented as a mixed client\\/server-based system. Conclusions drawn from previous work include the need for systematic user studies of WebSDSS, and the adoption of

Claus Rinner

2003-01-01

413

Spatial Pattern Switching Enables Cyclic Evolution in Spatial Epidemics  

PubMed Central

Infectious diseases often spread as spatial epidemic outbreak waves. A number of model studies have shown that such spatial pattern formation can have important consequences for the evolution of pathogens. Here, we show that such spatial patterns can cause cyclic evolutionary dynamics in selection for the length of the infectious period. The necessary reversal in the direction of selection is enabled by a qualitative change in the spatial pattern from epidemic waves to irregular local outbreaks. The spatial patterns are an emergent property of the epidemic system, and they are robust against changes in specific model assumptions. Our results indicate that emergent spatial patterns can act as a rich source for complexity in pathogen evolution.

2010-01-01

414

The European Regional Convergence Process, 1980-1995: Do Spatial Regimes and Spatial Dependence Matter?  

Microsoft Academic Search

The authors show that spatial dependence and spatial heterogeneity matter in the estimation of the &bgr;-convergence process among 138 European regions over the 1980 to 1995 period. Using spatial econometrics tools, the authors detect both spatial dependence and spatial heterogeneity in the form of structural instability across spatial convergence clubs. The estimation of the appropriate spatial regimes spatial error model

Cem Ertur; Julie Le Gallo; Catherine Baumont

2006-01-01

415

Controlling dynamics in spatially extended systems  

NASA Astrophysics Data System (ADS)

Spatially extended systems exhibit a variety of spatiotemporal dynamics-from stable to chaotic. These dynamics can change under pathological conditions and impair normal functions. Thus, having the ability to control the altered dynamics for improved functioning has the potential for wide ranging applications in real and artificial systems. Here we propose a simple and general method that can be used to target the spatiotemporal dynamics, both globally and in spatially localized regions, in either direction-i.e., towards the stable or unstable manifold-by simply changing the strength and the sign of an externally applied perturbation or pinning. The method is applicable to both chaotic and nonchaotic systems, with discrete and continuous local dynamics, and for different topologies of interactions. We also apply it to simulate an experiment on epileptogenic neuronal activity in rat hippocampal tissue [B. J. Gluckman et al., J. Neurophys. 76, 6202 (1996)]. This unified approach for differential targeting of global and local dynamics promises to be useful for systems spanning large spatial scales and having structural and functional heterogeneity.

Parekh, Nita; Sinha, Somdatta

2002-03-01

416

Ontology-based semantic integration of GML spatial information  

NASA Astrophysics Data System (ADS)

GML is an XML encoding for the modeling, transport and storage of geographic information, which has been making a significant influential on the ability of organizations to share geographic information among their Web based GIS applications. Ontology has been acknowledged to be the kernel methodology for capturing and sharing semantics of spatial information. This paper proposes a framework for integrating spatial information based on GML schema matching by using ontology technologies, in which GML is adopted as the common format for spatial information wrapping and mediation, and ontology is used to overcome the heterogeneity when matching different GML schemas. A prototype is also implemented based on the proposed framework.

Zhou, Jiaogen; Guan, Jihong; Zhu, Fubao; Zhou, Shuigeng; Li, Pingxiang

2006-10-01

417

Visualized Spatial Data Classifying Based on Spatial Data Mining  

Microsoft Academic Search

A spatial data mining prototype system called Visual Geo-Classify System (VGCS) use to classify spatial data based on VC++6.0 is designed and developed. The authors used examples of data verified the effectiveness on system performance, algorithms and rules. The results indicate that this prototype system is a practical and extensible Visual Interactive Spatial Data Mining tool, it can achieve the

Zelu Jia; Yaolin Liu

2009-01-01

418

Computationally efficient spatial interpolators based on spartan spatial random fields  

Microsoft Academic Search

This paper addresses the spatial interpolation of scattered data in d dimensions. The problem is approached using the theory of Spartan spatial random fields (SSRFs), focusing on a specific Gaussian SSRF, i.e., the fluctuation-gradient-curvature (FGC) model. A family of spatial interpolators (predictors) is formulated by maximizing the FGC-SSRF probability density function at each prediction point, conditioned by the data. An

Dionissios T. Hristopulos; Samuel N. Elogne

2009-01-01

419

Spatial models with spatially lagged dependent variables and incomplete data  

Microsoft Academic Search

The purpose of this paper is to suggest estimators for the parameters of spatial models containing a spatially lagged dependent\\u000a variable, as well as spatially lagged independent variables, and an incomplete data set. The specifications allow for nonstationarity,\\u000a and the disturbance process of the model is specified non-parametrically. We consider various scenarios concerning the pattern\\u000a of missing data points. One

Harry H. KelejianIngmar; Ingmar R. Prucha

2010-01-01

420

Spatial uncertainty analysis: Propagation of interpolation errors in spatially distributed models  

USGS Publications Warehouse

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 inputs.

Phillips, D. L.; Marks, D. G.

1996-01-01

421

Programmable fabrication of spatial structures in a gas jet by laser machining with a spatial light modulator  

SciTech Connect

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.

Lin, M.-W.; Chen, Y.-M.; Pai, C.-H.; Kuo, C.-C.; Lee, K.-H.; Wang, J.; Chen, S.-Y.; Lin, J.-Y. [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China)

2006-11-15

422

Spatial perception and control.  

PubMed

We investigated whether the perceived vanishing point of a moving stimulus becomes more accurate as one's degree of control over the stimulus increases. Either alone or as a member of a pair, participants controlled the progression of a dot stimulus back and forth across a computer monitor. They did so via right and left buttonpresses that incremented the dot's velocity rightward and leftward, respectively. The participants in the individual condition had control of both buttons. Those in the group condition had control of only one. As the participants slowed the dot to change its direction of travel, it unexpectedly disappeared. Localizations of the vanishing point became more accurate as the participants' control over the dot increased. The data bridge a gap between accounts of localization error that rely solely on stimulus and cognitive factors, and accounts derived from research on action and spatial perception, which tend to rely on action-planning factors. PMID:15116986

Jordan, J Scott; Knoblich, Günther

2004-02-01

423

Spatial pinning control.  

PubMed

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. PMID:23003148

Frasca, Mattia; Buscarino, Arturo; Rizzo, Alessandro; Fortuna, Luigi

2012-05-15

424

Cell culture device using spatial light modulator  

NASA Astrophysics Data System (ADS)

Spatial light modulator is introduced for cell culturing and related illumination experiment. Two kinds of designs were used. The first type put the cell along with the bio-medium directly on top of the analyzer of the microdisplay and set a cover glass on it to retain the medium environment, which turned the microdisplay into a bio-container. The second type introduced an optical lens system placed below the spatial light modulator to focus the light spots on specific position. Details of the advantages and drawbacks for the two different approaches are discussed, and the human melanocyte cell (HMC) is introduced to prove the feasibility of the concept. Results indicate that the second type is much more suitable than the first for precision required application.

Ou, Chung-Jen; Shen, Ching-I.; Ou, Chung-Ming

2009-07-01

425

Hierarchical Data Structures for Accessing Spatial Data  

NASA Astrophysics Data System (ADS)

Spatial data is data related to space .In various application fields like GIS, multimedia information systems, etc., there is a need to store and manage these data. Some data structures used for the spatial access methods are R tree and its extensions where objects could be approximated by their minimum bounding rectangles and Quad tree based structures where space is subdivided according to certain rules. Also another structure KD Tree is used for organizing points in a k dimensional space. In this paper we have described an algorithm for insertion of points in a Quad tree based structure, known as PR Quad Tree. Another data structure called K-D Tree is also described and the insertion procedure is defined. Then the comparison between the two structures is drawn.

Samaddar, Rituparna; Samaddar, Sandip; Kim, Tai-Hoon; Bhattacharyya, Debnath

426

Pennsylvania Spatial Data Access and Online Advanced Spatial Information Systems  

Microsoft Academic Search

The Pennsylvania Spatial Data Access system (PASDA) is Pennsylvania's official geospatial information clearinghouse and the Commonwealth's node on the National Spatial Data Infrastructure. The PASDA clearinghouse provides for the widespread sharing of geospatial data, eliminates the creation of redundant data sets, and serves as a resource for locating data throughout the Commonwealth through its comprehensive standardized data storage, online free

H. Lin; G. Petersen; M. Kelly; R. Day

2002-01-01

427

The spatial analysis service basing on the Spatial Information Grid  

Microsoft Academic Search

The core elements of Web GIS are spatial information processing and spatial data. It means that the flexibility of the Web GIS system depends on the cross-platform processing and the capability to analyze the heterogeneous data. Even though Web services are employed to add Web GIS the capabilities of cross-platform processing, the heterogeneous data still can not be well analyzed.

Yunxuan Yan; Guoqing Li; Yi Zeng; Jibo Xie

2009-01-01

428

Constructing Spatial Meaning: Spatial Affordances in Museum Design  

ERIC Educational Resources Information Center

Informal education in museums is structured through movement in space. This article summarizes a range of research that examines the role of spatial layout in shaping the ways in which visitors explore, engage, and understand museums and museum exhibitions. It is demonstrated that behavior patterns are systematically linked to spatial

Wineman, Jean D.; Peponis, John

2010-01-01

429

Expansive spatial planning: the new European transnational spatial visions  

Microsoft Academic Search

Spatial planning in Europe has reached new frontiers. The European Spatial Development Perspective covers the entire European Union and, in spite of having an informal, non-binding status, it is creeping into the regulatory frameworks of the European Union. To stimulate cooperation between the Member States of the European Union, including the accession countries, the map of Europe has been divided

Wil Zonneveld

2005-01-01

430

Spatial queries with qualitative locations in spatial information systems  

Microsoft Academic Search

We discuss locations as defined by their qualitative spatial relations to other features, dubbed qualitative locations (QL). We further propose a mechanism to handle queries with qualitative locations in geospatial information systems. For the realization of the mechanism for QL-based queries, we propose a conceptual framework that takes advantage of models of qualitative spatial reasoning to bridge the gap between

Xiaobai Yao; Jean-claude Thill

2006-01-01

431

Low Voltage Spatial Light Modulator  

SciTech Connect

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 advanced actuator is coupled with non-linear springs, the response curve becomes even more linear. The response curve of the springs is tailored to produce an actuator with extremely linear displacement vs. voltage characteristics.

Papavasiliou, A

2003-02-19

432

Modeling for spatial multilevel structural data  

NASA Astrophysics Data System (ADS)

The traditional multilevel model assumed independence between groups. However, the datasets grouped by geographical units often has spatial dependence. The individual is influenced not only by its region but also by the adjacent regions, and level-2 residual distribution assumption of traditional multilevel model is violated. In order to deal with such spatial multilevel data, we introduce spatial statistics and spatial econometric models into multilevel model, and apply spatial parameters and adjacency matrix in traditional level-2 model to reflect the spatial autocorrelation. Spatial lag model express spatial effects. We build spatial multilevel model which consider both multilevel thinking and spatial correlation.

Min, Suqin; He, Xiaoqun

2013-03-01

433

Predicting brain activity using a Bayesian spatial model.  

PubMed

Increasing the clinical applicability of functional neuroimaging technology is an emerging objective, e.g. for diagnostic and treatment purposes. We propose a novel Bayesian spatial hierarchical framework for predicting follow-up neural activity based on an individual's baseline functional neuroimaging data. Our approach attempts to overcome some shortcomings of the modeling methods used in other neuroimaging settings, by borrowing strength from the spatial correlations present in the data. Our proposed methodology is applicable to data from various imaging modalities including functional magnetic resonance imaging and positron emission tomography, and we provide an illustration here using positron emission tomography data from a study of Alzheimer's disease to predict disease progression. PMID:22743280

Derado, Gordana; Bowman, F Dubois; Zhang, Lijun

2012-06-28

434

Spatial speckle characterization by Brownian motion analysis  

NASA Astrophysics Data System (ADS)

It is well known that interactions between a coherent monochromatic radiation and a scattering media induce a speckle phenomenon. Spatial and temporal statistics of this speckle allow many applications in laser imaging. The main problem is the characterization of the backscattered media from the speckle pattern in biomedical imagery. In this paper, we present a st