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Spatial Hierarchy and OLAP-Favored Search in Spatial Data Warehouse  

E-print Network

not fully exploit spatial data in coordinates because multi- dimensional spatial data does not have implicit we extend the traditional set-grouping hi- erarchy into multi-dimensional data space and propose. To process spa- tial OLAP query in spatial data warehouse, we propose an OLAP- favored search method which

Song, Il-Yeol


Efficient OLAP Operations in Spatial Data Warehouses  

Microsoft Academic Search

Spatial databases store information about the position of individual objects in space. In many applications however, such as traffic supervision or mobile communications, only summarized data, like the number of cars in an area or phones serviced by a cell, is required. Although this information can be obtained from transactional spatial databases, its computation is expensive, rendering online processing inapplicable.

Dimitris Papadias; Panos Kalnis; Jun Zhang; Yufei Tao



An interoperable XML encoding for the exchange of Spatial OLAP data cubes in SOA environments  

E-print Network

popularity as a data exchange format on the Internet. Along with the growing acceptance of Service Oriented on the Internet. Meanwhile, Spatial OLAP (SOLAP) tools have emerged to bridge the gap between the Business


Data mining and automatic OLAP schema generation  

Microsoft Academic Search

Data mining aims at extraction of previously unidentified information from large databases. It can be viewed as an automated application of algorithms to discover hidden patterns and to extract knowledge from data. Online Analytical Processing (OLAP) systems, on the other hand, allow exploring and querying huge datasets in interactive way. These OLAP systems are the predominant front-end tools used in

Muhammad Usman; Sohail Asghar; Simon Fong



Efficient OLAP Operations in Spatial Data Warehouses Dimitris Papadias, Panos Kalnis, Jun Zhang and Yufei Tao  

E-print Network

, and the cube cells contain a measure, such as sales. Recently, the popularity of spatial information supervision or mobile communications, only summarized data, like the number of cars in an area or phones serviced by a cell, is required. Although this information can be obtained from transactional spatial

Papadias, Dimitris


Efficient OLAP Query Processing in Distributed Data Warehouses  

Microsoft Academic Search

The success of Internet applications has led to an explo- sive growth in the demand for bandwidth from ISPs. Managing an IP network requires collecting and analyzing network data, such as o w- level trac statistics. Such analyses can typically be expressed as OLAP queries, e.g., correlated aggregate queries and data cubes. Current day OLAP tools for this task assume

Michael O. Akinde; Michael H. Böhlen; Theodore Johnson; Laks V. S. Lakshmanan; Divesh Srivastava



Efficient OLAP query processing in distributed data warehouses  

Microsoft Academic Search

The success of Internet applications has led to an explosive growth in the demand for bandwidth from Internet Service Providers. Managing an Internet protocol network requires collecting and analyzing network data, such as flow-level traffic statistics. Such analyses can typically be expressed as OLAP queries, e.g., correlated aggregate queries and data cubes. Current day OLAP tools for this task assume

Michael O. Akinde; Michael H. Böhlen; Theodore Johnson; Laks V. S. Lakshmanan; Divesh Srivastava



Spatial OLAP Modeling: An Overview Base on Spatial Objects Changing over Gabriel Pestana Miguel Mira da Silva Yvan Bdard  

E-print Network

at design time to efficiently compute pre- aggregation in the DW [3]. One alternative is to follow a data making process to support spatial queries is not a trivial task. This task becomes even harder when using difficulties on indexing issues and on the associated query mechanisms. On the other hand, a typical DW


Repairing OLAP Queries in Databases with Referential Integrity Errors  

E-print Network

applications and OLAP tools dy- namically generate SQL queries involving join operators and aggregate functions integrity and take almost the same time as original queries, highlighting efficiency is good and overhead calls aggregate functions. The method consists in rewriting queries that use joins where foreign keys

Ordonez, Carlos


Object-Based Selective Materialization for Efficient Implementation of Spatial Data Cubes  

Microsoft Academic Search

With a huge amount of data stored in spatial databases and the introduction of spatial components to many relational or object-relational databases, it is important to study the methods for spatial data warehousing and OLAP of spatial data. In this paper, we study methods for spatial OLAP, by integration of nonspatial OLAP methods with spatial database implementation techniques. A spatial

Nebojsa Stefanovic; Jiawei Han; Krzysztof Koperski



Predicting your next OLAP query based on recent analytical sessions  

E-print Network

the efficiency of OLAP sessions on the other. In particular, query recommendation would proactively guide users, usability, and efficiency of modern OLAP systems, the huge number of possible aggregations and selectionsPredicting your next OLAP query based on recent analytical sessions Marie-Aude Aufaure1 , Nicolas

Paris-Sud XI, Université de


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



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

PubMed Central

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 multidimensional datawarehouse designed to facilitate querying of large numerical data. Coupling the spatial capabilities of GIS with the numerical analysis of OLAP, might enhance CHA data analysis. OLAP-GIS systems have been developed by university researchers and corporations, yet their potential for CHA data analysis is not well understood. To evaluate the potential of an OLAP-GIS decision support system for CHA problem solving, we compared OLAP-GIS to the standard information technology (IT) currently used by many public health professionals. Methods SOVAT, an OLAP-GIS decision support system developed at the University of Pittsburgh, was compared against current IT for data analysis for CHA. For this study, current IT was considered the combined use of SPSS and GIS ("SPSS-GIS"). Graduate students, researchers, and faculty in the health sciences at the University of Pittsburgh were recruited. Each round consisted of: an instructional video of the system being evaluated, two practice tasks, five assessment tasks, and one post-study questionnaire. Objective and subjective measurement included: task completion time, success in answering the tasks, and system satisfaction. Results Thirteen individuals participated. Inferential statistics were analyzed using linear mixed model analysis. SOVAT was statistically significant (? = .01) from SPSS-GIS for satisfaction and time (p < .002). Descriptive results indicated that participants had greater success in answering the tasks when using SOVAT as compared to SPSS-GIS. Conclusion Using SOVAT, tasks were completed more efficiently, with a higher rate of success, and with greater satisfaction, than the combined use of SPSS and GIS. The results from this study indicate a potential for OLAP-GIS decision support systems as a valuable tool for CHA data analysis. PMID:18541037

Scotch, Matthew; Parmanto, Bambang; Monaco, Valerie



Data Warehousing & OLAP Chapter 25, Ramakrishnan & Gehrke  

E-print Network

such On-Line Analytic Processing (OLAP) with traditional On-line Transaction Processing (OLTP): mostly on spreadsheet-style operations and "multidimensional" view of data. ­ Interactive and "online" queries. · Data;MOLAP vs ROLAP · Multidimensional data can be stored physically in a (disk- resident, persistent) array

Lakshmanan, Laks V.S.


Range Queries in OLAP Data Cubes  

Microsoft Academic Search

A range query applies an aggregation operation over all selectedcells of an OLAP data cube where the selection isspecified by providing ranges of values for numeric dimensions.We present fast algorithms for range queries for twotypes of aggregation operations: SUM and MAX. These twooperations cover techniques required for most popular aggregationoperations, such as those supported by SQL.For range-sum queries, the essential

Ching-Tien Ho; Rakesh Agrawal; Nimrod Megiddo; Ramakrishnan Srikant



Efficient Updates for OLAP Range Queries on Flash Memory  

E-print Network

, gender is male or female and job is {teacher, manager, clerk, none}. The data cube will have 100 � 2 � 4Efficient Updates for OLAP Range Queries on Flash Memory Mitzi McCarthy and Zhen He; This paper explores efficient ways to use flash memory to store OLAP data

He, Zhen


On the Performance of an Array-Based ADT for OLAP Workloads  

Microsoft Academic Search

There is currently a debate among OLAP vendors on the best way to provide OLAP functionality: RelationalOLAP (ROLAP) vendors advocate using sophisticated front ends to provide a multidimensional view of a standardrelational database, whereas Multidimensional OLAP (MOLAP) vendors provide custom servers that generallystore their data as arrays (instead of tables.) An important question in this debate is the relative performanceof

Yihong Zhao Kristin Tufte



Discovery-Driven Exploration of OLAP Data Cubes  

Microsoft Academic Search

.Analysts predominantly use OLAP data cubes to identifyregions of anomalies that may represent problem areas or new opportunities.The current OLAP systems support hypothesis-driven explorationof data cubes through operations such as drill-down, roll-up, and selection.Using these operations, an analyst navigates unaided through ahuge search space looking at large number of values to spot exceptions.We propose a new discovery-driven exploration paradigm that

Sunita Sarawagi; Rakesh Agrawal; Nimrod Megiddo



An efficient communication strategy for mobile agent based distributed spatial data mining application  

NASA Astrophysics Data System (ADS)

An efficient communication strategy is proposed in this paper, which aims to improve the response time and availability of mobile agent based distributed spatial data mining applications. When dealing with decomposed complex data mining tasks or On-Line Analytical Processing (OLAP), mobile agents authorized by the specified user need to coordinate and cooperate with each other by employing given communication method to fulfill the subtasks delegated to them. Agent interactive behavior, e.g. messages passing, intermediate results exchanging and final results merging, must happen after the specified path is determined by executing given routing selection algorithm. Most of algorithms exploited currently run in time that grows approximately quadratic with the size of the input nodes where mobile agents migrate between. In order to gain enhanced communication performance by reducing the execution time of the decision algorithm, we propose an approach to reduce the number of nodes involved in the computation. In practice, hosts in the system are reorganized into groups in terms of the bandwidth between adjacent nodes. Then, we find an optimal node for each group with high bandwidth and powerful computing resources, which is managed by an agent dispatched by agent home node. With that, the communication pattern can be implemented at a higher level of abstraction and contribute to improving the overall performance of mobile agent based distributed spatial data mining applications.

Han, Guodong; Wang, Jiazhen



Consistency-aware Evaluation of OLAP Queries in Replicated Data Warehouses  

E-print Network

1 Consistency-aware Evaluation of OLAP Queries in Replicated Data Warehouses Javier Garc of Houston Houston, TX 77204, USA Abstract--OLAP tools for distributed data warehouses gener- ally assume to evaluate OLAP queries in distributed data warehouses assuming a lazy replication model. Considering

Ordonez, Carlos


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 sets…

Sharoupim, Magdy S.



Database, Spatial Spatial databases are the foundation for computer-based applications involving spatially  

E-print Network

Database, Spatial Spatial databases are the foundation for computer-based applications involving, an orientation and a size). Spatial databases can be implemented using various technologies, the most common now to their intended purpose. There are two categories of spatial databases: transactional and analytical


Hybrid OLTP&OLAP High Performance Database Reference Number  

E-print Network

) queries that process substantial portions of the data in order to generate reports for business analysts. Typical reports include the aggregated sales statistics grouped by geographical regions, or by product an efficient hybrid system, called HyPer, that can handle both OLTP and OLAP simultaneously by using hardware


OLAP-based Query Recommendation Carlos Garcia-Alvarado  

E-print Network

. Although both methods are quite efficient in the computa- tion of aggregations, performing such a taskOLAP-based Query Recommendation Carlos Garcia-Alvarado University of Houston Dept. of Computer Carlos Ordonez University of Houston Dept. of Computer Science Houston, TX, USA ABSTRACT Query

Ordonez, Carlos


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.



Emerging Cubes for Trends Analysis in OlapDatabases  

Microsoft Academic Search

In various approaches, data cubes are pre-computed in order to efficiently answer Olap queries. Such cubes are also successfully used for multidimensional analysis of data streams. In this paper, we address the\\u000a issue of performing cube comparisons in order to exhibit trend reversals between two cubes. Mining such trend changes provides\\u000a users with a novel and specially interesting knowledge. For

Sébastien Nedjar; Alain Casali; Rosine Cicchetti; Lotfi Lakhal



Applying Multidimensional Scaling Analysis for Finding Similarity Knowledge in OLAP Reports  

Microsoft Academic Search

On Line Analysis Processing (OLAP) is a common solution that modern enterprises use to generate, monitor, share, and administrate their analysis reports. When daily, weekly, and\\/or monthly reports are generated or published by the OLAP operators, the report readers can only rely on their smart eyes to find out hidden rules, similar reports, or trend inside the potentially huge amount

Kevin Chihcheng Hsu; Ming-Zhong Li



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



A Conceptual Model for Combining Enhanced OLAP and Data Mining Systems  

Microsoft Academic Search

Online Analytical Processing (OLAP) was widely used to visualize complex data for efficient, interactive and meaningful analysis. Its power comes in visualizing huge operational data for interactive analysis. On the other hand, data mining techniques (DM) are strong at detecting patterns and mining knowledge from historical data. OLAP and DM is believed to be able to complement each other to

Muhammad Usman; Sohail Asghar; Simon Fong



Selective Materialization: An Efficient Method for Spatial Data Cube Construction  

Microsoft Academic Search

. On-line analytical processing (OLAP) has gained its popularityin database industry. With a huge amount of data stored in spatialdatabases and the introduction of spatial components to many relationalor object-relational databases, it is important to study the methods forspatial data warehousing and on-line analytical processing of spatialdata. In this paper, we study methods for spatial OLAP, by integrationof nonspatial on-line

Jiawei Han; Nebojsa Stefanovic; Krzysztof Koperski



Raster graphics for spatial applications  

Microsoft Academic Search

The greatest effective bandwidth of the eye is for changes in color and texture, so why does computer graphics emphasize line-drawings? Questions such as this brought about the MAPS Project in 1971 for the purpose of developing graphics systems suitable for geographic applications. The MAPS-1 system, operational since September 1974, and the MINIMAPS system now under development achieve high performance

Michael A. Fischer; Robert E. Nunley



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


IX-Cubes: Iceberg Cubes for Data Warehousing and OLAP on XML Data  

E-print Network

IX-Cubes: Iceberg Cubes for Data Warehousing and OLAP on XML Data Fianny Ming-fei Jian The Chinese is not available. In this paper, we introduce the IX-cube (Iceberg XML cube) over XML data to tackle the problem of supporting OLAP on XML data and develop an IX-Cube approach: we construct an iceberg data cube on an XML data

Pei, Jian


Managing Spatial Knowledge for Mobile Personalized Applications  

Microsoft Academic Search

\\u000a The continuing explosion in the amount of readily available spatial data has given rise to significant problems in accessing\\u000a the most task-relevant spatial information. At the same time, advances in mobile computing have yielded handheld platforms\\u000a powerful enough to deliver spatial information interactions, but with usability issues in interfacing and wireless data transmission.\\u000a We are developing techniques to manage information

Joe Weakliam; Daniel Lynch; Julie Doyle; Helen Min Zhou; Eoin Mac Aoidh; Michela Bertolotto; David C. Wilson



Effectiveness of OLAP-based cost data management in construction cost estimate  

Microsoft Academic Search

Historical cost data offer important information on the performance of past construction work, while current information technology makes it easier to develop databases. The database, however, needs to be utilized more, by providing a functional environment of probability analysis. The objective of this paper is to improve the effectiveness of utilizing historical cost data in an analytical OLAP (On-Line Analytical

S. W. Moon; J. S. Kim; K. N. Kwon



SOCQET: Semantic OLAP with Compressed Cube and Summarization Laks V.S. Lakshmanan  

E-print Network

SOCQET: Semantic OLAP with Compressed Cube and Summarization Laks V.S. Lakshmanan Jian Pei Yan Zhao cube, which can be viewed as a multi-level, multi-dimensional database with aggregate data at multiple granularity. In a data cube, two basic semantic relations among cells are roll up and drill down. A cell c1

Pei, Jian


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.




USGS Publications Warehouse

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

Miller, Betty M.; Domaratz, Michael A.



Parallel Star Join + DataIndexes: Efficient Query Processing in Data Warehouses and OLAP  

Microsoft Academic Search

Abstract—On-Line Analytical Processing (OLAP) refers to the technologies,that allow users to efficiently retrieve data from the data warehouse,for decision-support purposes. Data warehouses,tend to be extremely,large—it is quite possible for a data warehouse,to be hundreds of gigabytes to terabytes in size [3]. Queries tend to be complex and ad hoc, often requiring computationally expensive operations such as joins and aggregation. Given

Anindya Datta; Debra E. Vandermeer; Krithi Ramamritham



Radiographic applications of spatial frequency multiplexing  

NASA Technical Reports Server (NTRS)

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

Macovski, A.



Extensions to Time Warp Parallel Simulation for Spatial Decomposed Applications  

E-print Network

Extensions to Time Warp Parallel Simulation for Spatial Decomposed Applications Benno J. Overeinder systems puts some extra requirements on the parallel syn- chronization schemes such as Time Warp. The large sci- entific problems require efficient memory management-- both time and space efficient

Amsterdam, Universiteit van


Spatial Bloom Filters: Enabling Privacy in Location-aware Applications  

E-print Network

systems such as a GPS receiver. The ability to track a user's position raises however deep privacySpatial Bloom Filters: Enabling Privacy in Location-aware Applications Paolo Palmieri1 , Luca, highly sensitive information: the user's privacy can be preserved if only the minimum amount


Design and implementation of GGEarth spatial data service application system  

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

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

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



New Sampling-Based Estimators for OLAP Queries  

Microsoft Academic Search

One important way in which sampling for approximate query processing in a database environment differs from tra- ditional applications of sampling is that in a database, it is feasible to collect accurate summary statistics from the data in addition to the sample. This paper describes a set of sampling-based estimators for approximate query processing that make use of simple summary

Ruoming Jin; Leonid Glimcher; Chris Jermaine; Gagan Agrawal



Merging Hypermedia GIS with Spatial On-Line Analytical Processing: Towards Hypermedia SOLAP  

E-print Network

(s)), Geographic Hypermedia: Concepts and Systems . accept� #12;information adheres to the way human brains thinkMerging Hypermedia GIS with Spatial On-Line Analytical Processing: Towards Hypermedia SOLAP Yvan B Systems (GIS) with those of On-Line Analytical Processing (OLAP), paving the way to a new technology


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



Vanadium dioxide spatial light modulator for applications beyond 1200 nm  

NASA Astrophysics Data System (ADS)

Spatial light modulators based on vanadium dioxide are used to demonstrate all-optical spectral filtering in the near infrared, up to 1700 nm, with potential to application into the mid-infrared. By spectrally dispersing the shaped beam and transmitting the beam through a vanadium dioxide thin film, the transmission is modified by optically pumping the film locally with a laser beam. Heating causes the film to undergo an insulator-to-metal transition, along with a drop in transmission. The spectrum can be shaped by pumping with a beam at different location and/or different intensity profiles. The method is promising for longer wavelength since the film is more efficient further in the infrared.

Anh Do, Phuong; Hendaoui, Ali; Mortazy, Ebrahim; Chaker, Mohamed; Haché, Alain



Spatial and statistical GIS Applications for geological and environmental courses  

NASA Astrophysics Data System (ADS)

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

Marsellos, A.; Tsakiri, K.



Spectral extrapolation of spatially bounded images [MRI application  

Microsoft Academic Search

A spectral extrapolation algorithm for spatially bounded images is presented. An image is said to be spatially bounded when it is confined to a closed region and is surrounded by a background of zeros. With prior knowledge of the spatial domain zeros, the extrapolation algorithm extends the image's spectrum beyond a known interval of low-frequency components. The result, which is

Sylvia K. Plevritis; Albert Macovski



Truthful Color Reproduction in Spatial Augmented Reality Applications.  


Spatial augmented reality is especially interesting for the design process of a car, because a lot of virtual content and corresponding real objects are used. One important issue in such a process is that the designer can trust the visualized colors on the real object, because design decisions are made on basis of the projection. In this article, we present an interactive visualization technique which is able to exactly compute the RGB values for the projected image, so that the resulting colors on the real object are equally perceived as the real desired colors. Our approach computes the influences of the ambient light, the material, the pose and the color model of the projector to the resulting colors of the projected RGB values by using a physically-based computation. This information allows us to compute the adjustment for the RGB values for varying projector positions at interactive rates. Since the amount of projectable colors does not only depend on the material and the ambient light, but also on the pose of the projector, our method can be used to interactively adjust the range of projectable colors by moving the projector to arbitrary positions around the real object. We further extend the mentioned method so that it is applicable to multiple projectors. PMID:22732680

Menk, Christoffer; Koch, Reinhard




E-print Network

A SPATIAL OVERCONSTRAINED MECHANISM THAT CAN BE USED IN PRACTICAL APPLICATIONS Constantinos Mavroidis, Assistant Professor Michael Beddows, Research Assistant Department of Mechanical and Aerospace mechanism is presented that can be used in many practical applications. It is a 5 link 4R1P spatial

Mavroidis, Constantinos


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. PMID:23923094

Studnicki, James; Fisher, John W.



Spatial processing techniques for satellite altimetry applications in continental hydrology  

NASA Astrophysics Data System (ADS)

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

Maillard, Philippe; Calmant, Stéphane



A Framework for Developing Real-Time OLAP algorithm using Multi-core processing and GPU: Heterogeneous Computing  

NASA Astrophysics Data System (ADS)

The overwhelmingly increasing amount of stored data has spurred researchers seeking different methods in order to optimally take advantage of it which mostly have faced a response time problem as a result of this enormous size of data. Most of solutions have suggested materialization as a favourite solution. However, such a solution cannot attain Real-Time answers anyhow. In this paper we propose a framework illustrating the barriers and suggested solutions in the way of achieving Real-Time OLAP answers that are significantly used in decision support systems and data warehouses.

Alzeini, H. I.; Hameed, Sh A.; Habaebi, M. H.



GIS application on spatial landslide analysis using statistical based models  

NASA Astrophysics Data System (ADS)

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

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



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



Full Spatial Resolution Infrared Sounding Application in the Preconvection Environment  

NASA Astrophysics Data System (ADS)

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

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



Application and Optimisation of the Spatial Phase Shifting Technique in  

E-print Network

83 3.4.3 Relation of speckle size and magnification 85 3.4.4 Spatial phase shifting on speckle fields unwrapping of speckle phases 166 6.7.2 Long-term observation of biological object 168 6.7.3 Relative

Hinsch, Klaus



E-print Network

is founded on the tesseral repre­ sentation incorporated into the SPARTA (SPAtial Reasoning using Tesseral an overview of the SPARTA tesseral representation together with some brief notes on tesseral representations are presented together with a number of questions and issues to be resolved. 2 THE SPARTA TESSERAL

Atkinson, Katie



E-print Network

Based Reasoning (CBR). The representation used is founded on the SPARTA (SPAtial Reasoning using gives an overview of the SPARTA tesseral representation together with brief notes on tesseral representations in general, data storage and tesseral arithmetic. An outline of the SPARTA scripting language used

Atkinson, Katie


Spatial Competition and market Share: An Application to Motion Pictures  

Microsoft Academic Search

This paper presents an empirical assessment of movie theatre attendance in two major metropolitan markets and provides strong support for the importance of spatial characteristics in determing attendance. We consider the hypothesis that attendance at particular movie theatres reflects a tension between two effects: a negative competion effect and a positive agglomeration effect. We find evidence that the competition effect

Darlene C. Chisolm; George Norman



Spatial Competition and Demand: An Application to Motion Pictures  

Microsoft Academic Search

This paper provides a rich assessment of the demand characteristics for movie theatre attendance in two major metropolitan markets and provides strong support for the importance of spatial characteristics in empirical demand analysis. We provide evidence of the usual competitive effect of location on an exhibitor’s demand but also find evidence of a clustering effect: when a group of theatres

Darlene C. Chisholm; George Norman



Spatial Competition and Agglomeration: An Application to Motion Pictures  

Microsoft Academic Search

This paper presents an empirical assessment of movie theatre attendance in two major metropolitan markets and provides strong support for the importance of spatial characteristics in determining attendance. We consider the hypothesis that attendance at a particular movie theatre reflects a tension between two effects: a competition effect and an agglomeration effect. We find evidence that the agglomeration effect dominates.

Darlene C. Chisholm; George Norman


Qualitative Spatial Reasoning about Objects in Motion: Application to Physics Problem Solving  

E-print Network

, such as Resnick and Halliday's Physics text [17], are an in­ teresting source of problems as they contain bothQualitative Spatial Reasoning about Objects in Motion: Application to Physics Problem Solving Raman

Kuipers, Benjamin


Selected properties of optical spatial solitons in photorefractive media and their important applications  

E-print Network

Some selected important properties of photorefractive spatial solitons and their applications have been reviewed in the present paper. Using band transport model, the governing principle of photorefractive nonlinearity has been addressed and nonlinear dynamical equations of spatial solitons owing to this nonlinearity have been discussed. Mechanisms of formation of screening and photovoltaic solitons of three different configurations i.e., bright, dark and grey varieties have been examined. Incoherently coupled vector solitons due to single and two-photon photorefractive phenomena have been highlighted. Modulation instability, which is precursor to soliton formation has been also discused briefly. Finally possible applications of photorefractive spatial solitons have been highlighted.

Konar, S



Nonparametric Spatial Models for Extremes: Application to Extreme Temperature Data*  

PubMed Central

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

Fuentes, Montserrat; Henry, John; Reich, Brian



Tract-Based Spatial Statistics: Application to Mild Cognitive Impairment  

PubMed Central

Rationale and Objectives. The primary objective of the current investigation was to characterize white matter integrity in different subtypes of mild cognitive impairment (MCI) using tract-based spatial statistics of diffusion tensor imaging. Materials and Methods. The study participants were divided into 4 groups of 30 subjects each as follows: cognitively healthy controls, amnestic MCI, dysexecutive MCI, and Alzheimer's disease (AD). All subjects underwent a comprehensive neuropsychological assessment, apolipoprotein E genotyping, and 3-tesla MRI. The diffusion tensor was reconstructed and then analyzed using tract-based spatial statistics. The changes in brain white matter tracts were also examined according to the apolipoprotein E ?4 status. Results. Compared with controls, amnestic MCI patients showed significant differences in the cerebral white matter, where changes were consistently detectable in the frontal and parietal lobes. We found a moderate impact of the apolipoprotein E ?4 status on the extent of white matter disruption in the amnestic MCI group. Patients with AD exhibited similar but more extensive alterations, while no significant changes were observed in dysexecutive MCI patients. Conclusion. The results from this study indicate that amnestic MCI is the most likely precursor to AD as both conditions share significant white matter damage. By contrast, dysexecutive MCI seems to be characterized by a distinct pathogenesis. PMID:24900978

Wai, Yau-Yau; Hsu, Wen-Chuin; Fung, Hon-Chung; Lee, Jiann-Der; Chan, Hsiao-Lung; Tsai, Ming-Lun; Lin, Yu-Chun; Wu, Yih-Ru; Ying, Leslie; Wang, Jiun-Jie



Bayesian Models for Spatial Extremes Application to inferring high values of  

E-print Network

Bayesian Models for Spatial Extremes Application to inferring high values of ground-level ozone): · carbon monoxide (CO), · lead (Pb), · nitrogen dioxide (NO2), · ground-level Ozone (O3), · particulate by the National Science Foundation (NSF) #12;Outline · Background to Ozone Application · Background to Extreme

Gilleland, Eric


A Spatial Programming Model for Real Global Smart Space Applications  

Microsoft Academic Search

Global smart spaces are intended to provide their inhabitants with context-aware access to pervasive services and information relevant to large geographical areas. Transportation is one obvious domain for such global smart spaces since applications can be built to exploit the variety of sensor-rich systems that have been deployed to support urban traffic control and highway management as well as within

René Meier; Anthony Harrington; Thomas Termin; Vinny Cahill



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



Full-Stokes UV and visible spectropolarimeter for spatial application  

NASA Astrophysics Data System (ADS)

UVMag is a project of a space mission equipped with a high-resolution spectropolarimeter working in the UV and visible range. This M-size mission will be proposed to ESA. The main goal of UVMag is to measure the magnetic fields, winds and environment of all types of stars to reach a better understanding of stellar formation and evolution. The groundbreaking combination of a UV and visible observation will allow the scientists to study the star and its environment simultaneously. The baseline wavelength window for spectropolarimetry is between 117nm and 870nm, in order to observe the polarization state in many important spectral lines. We also aim at extending the window down to 90 nm at least in spectroscopy. The UV domain contains key atomic and molecular transitions, for example for hot stars, and is the best domain to study Sun-like stars or white dwarfs. The instrumental challenge for this mission is to design a high-resolution space spectropolarimeter measuring the full-Stokes vector of the observed star in a huge spectral range from FUV to the limit between visible and NIR. This spectral range is the main difficulty because of the lack of birefringent and transparent materials working at FUV and visible wavelengths at the same time. As the instrument will be launched into space, the polarimetry module has to be robust and therefore use if possible only static elements. I will present some concepts that we studied to build such a system, using spatial or temporal modulation or channeled polarimetry. The output of the full-Stokes robust polarimeter will correspond to the entrance slit of a high-resolution echelle spectrometer, which will disperse the echelle orders into several UV and visible detectors.

Pertenais, Martin; Neiner, Coralie; Petit, Pascal; Pares, Laurent


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



Probabilistic Conic Mixture Model and its Applications to Mining Spatial Ground Penetrating Radar Data  

E-print Network

Probabilistic Conic Mixture Model and its Applications to Mining Spatial Ground Penetrating Radar Data Huanhuan Chen Anthony G Cohn Abstract This paper proposes a probabilistic conic mixture model based approaches. By incorporating a swift conic fitting algorithm into the probabilistic mixture model

Leeds, University of


A Spatial Model of Tumor-Host Interaction: Application of Chemotherapy  

E-print Network

A Spatial Model of Tumor-Host Interaction: Application of Chemotherapy Peter Hinow Institute, January 6th 2009 Peter Hinow et al. Tumor-Host Interaction, Chemotherapy #12;Origin of this model. Tumor-Host Interaction, Chemotherapy #12;Collaborators Philip Gerlee, Alexander R. A. Anderson (Division

Hinow, Peter


A Spatial Econometric Approach to Measuring Pollution Externalities: An Application to Ozone Smog  

E-print Network

A Spatial Econometric Approach to Measuring Pollution Externalities: An Application to Ozone Smog C- ducing ozone smog. 1. Introduction In 1997, eight states in the northeastern United States filed Standard (NAAQS) for ozone smog. These petitions identified 31 states plus the District of Columbia

Lin, C.-Y. Cynthia


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


Application of THz probe radiation in low-coherent tomographs based on spatially separated counterpropagating beams  

NASA Astrophysics Data System (ADS)

A principle of designing a high-resolution low-coherent THz tomograph, which makes it possible to investigate media with a high spatial resolution (in the range ?0 - 2?0, where ?0 is the average probe wavelength) is considered. The operation principle of this tomograph implies probing a medium by radiation with a coherence length of 8?0 and recording a hologram of a focused image of a fixed layer of this medium using spatially separated counterpropagating object and reference beams. Tomograms of the medium studied are calculated using a temporal approach based on application of the time correlation function of probe radiation.

Kuritsyn, I. I.; Mandrosov, V. I.; Shkurinov, A. P.; Nazarov, M. M.; Cherkasova, O. P.



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



Spatial Aggregation: Data Model and Implementation  

E-print Network

Data aggregation in Geographic Information Systems (GIS) is only marginally present in commercial systems nowadays, mostly through ad-hoc solutions. In this paper, we first present a formal model for representing spatial data. This model integrates geographic data and information contained in data warehouses external to the GIS. We define the notion of geometric aggregation, a general framework for aggregate queries in a GIS setting. We also identify the class of summable queries, which can be efficiently evaluated by precomputing the overlay of two or more of the thematic layers involved in the query. We also sketch a language, denoted GISOLAP-QL, for expressing queries that involve GIS and OLAP features. In addition, we introduce Piet, an implementation of our proposal, that makes use of overlay precomputation for answering spatial queries (aggregate or not). Our experimental evaluation showed that for a certain class of geometric queries with or without aggregation, overlay precomputation outperforms R-tre...

Gomez, Leticia; Kuijpers, Bart; Vaisman, Alejandro



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

NASA Astrophysics Data System (ADS)

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

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



Recursive temporal-spatial information fusion with applications to target identification  

Microsoft Academic Search

Centralized\\/distributed recursive algorithms for temporal-spatial information integration using the Dempster-Shafer technique are developed. Compared with the Bayesian approach, the Dempster-Shafer technique has the strong capability of handling information uncertainties, which are particularly desirable in many applications. In the centralized integration algorithm, all information is pooled into the central processor and integrated. In contrast, the distributed integration algorithm shares the computational




Spatial-Temporal Affinity Propagation for Feature Clustering with Application to Traffic Video Analysis  

Microsoft Academic Search

\\u000a In this paper, we propose STAP (Spatial-Temporal Affinity Propagation), an extension of the Affinity Propagation algorithm\\u000a for feature points clustering, by incorporating temporal consistency of the clustering configurations between consecutive\\u000a frames. By extending AP to the temporal domain, STAP successfully models the smooth-motion assumption in object detection\\u000a and tracking. Our experiments on applications in traffic video analysis demonstrate the effectiveness

Jun Yang; Yang Wang; Arcot Sowmya; Jie Xu; Zhidong Li; Bang Zhang



Application of Wavelet Transform for Image Denoising of Spatially and Time Variable Astronomical Imaging Systems  

NASA Astrophysics Data System (ADS)

We report on our efforts to formulate algorithms for image signal processing with the spatially and time variant Point-Spread Function (PSF) and inhomogeneous noise of real imaging systems. In this paper we focus on application of the wavelet transform for denoising of the astronomical images with complicated conditions. They influence above all accuracy of the measurements and the new source detection ability. Our aim is to test the usefulness of Wavelet transform (as the standard image processing technique) for astronomical purposes.

Blažek, M.; Anisimova, E.; Páta, P.


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

PubMed Central

Background The R project includes a large variety of packages designed for spatial statistics. Google dynamic maps provide web based access to global maps and satellite imagery. We describe a method for displaying directly the spatial output from an R script on to a Google dynamic map. Methods This is achieved by creating a Java based web application which runs the R script and then displays the results on the dynamic map. In order to make this method easy to implement by those unfamiliar with programming Java based web applications, we have added the method to the options available in the R Web User Interface (Rwui) application. Rwui is an established web application for creating web applications for running R scripts. A feature of Rwui is that all the code for the web application being created is generated automatically so that someone with no knowledge of web programming can make a fully functional web application for running an R script in a matter of minutes. Results Rwui can now be used to create web applications that will display the results from an R script on a Google dynamic map. Results may be displayed as discrete markers and/or as continuous overlays. In addition, users of the web application may select regions of interest on the dynamic map with mouse clicks and the coordinates of the region of interest will automatically be made available for use by the R script. Conclusions This method of displaying R output on dynamic maps is designed to be of use in a number of areas. Firstly it allows statisticians, working in R and developing methods in spatial statistics, to easily visualise the results of applying their methods to real world data. Secondly, it allows researchers who are using R to study health geographics data, to display their results directly onto dynamic maps. Thirdly, by creating a web application for running an R script, a statistician can enable users entirely unfamiliar with R to run R coded statistical analyses of health geographics data. Fourthly, we envisage an educational role for such applications. PMID:22998945



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

NASA Astrophysics Data System (ADS)

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

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



Applicability and efficiency of near-optimal spatial encoding for dynamically adaptive MRI.  


Adaptive near-optimal MRI spatial encoding entails, for the acquisition of each image update in a dynamic series, the computation of encodes in the form of a linear algebra-derived orthogonal basis set determined from an image estimate. The origins of adaptive encoding relevant to MRI are reviewed. Sources of error of this approach are identified from the linear algebraic perspective where MRI data acquisition is viewed as the projection of information from the field-of-view onto the encoding basis set. The definitions of ideal and non-ideal encoding follow, with nonideal encoding characterized by the principal angles between two vector spaces. An analysis of the distribution of principal angles is introduced and applied in several example cases to quantitatively describe the suitability of a basis set derived from a specific image estimate for the spatial encoding of a given field-of-view. The robustness of adaptive near-optimal spatial encoding for dynamic MRI is favorably shown by results computed using singular value decomposition encoding that simulates specific instances of worst case data acquisition when all objects have changed or new objects have appeared in the field-of-view. The mathematical analysis and simulations presented clarify the applicability and efficiency of adaptively determined near-optimal spatial encoding throughout a range of circumstances as may typically occur during use of dynamic MRI. PMID:9469703

Zientara, G P; Panych, L P; Jolesz, F A



Properties and applications of two-dimensional optical spatial solitons in a quadratic nonlinear medium  

NASA Astrophysics Data System (ADS)

An experimental and numerical investigation into the properties of quadratic spatial solitons (QSS) formed in a potassium titanyl phosphate (KTP) crystal was performed. This type II phase-matched crystal allowed for spatial soliton formation in (2+1) dimensions due to the cascaded second-order nonlinearity. This nonlinearity allowed for a strong localized coupling of the three interacting fields through both second-harmonic generation (SHG) and optical parametric amplification (OPA). From these fundamental properties, potential applications were demonstrated. The properties of type II QSS formed during SHG with unequal fundamental polarization components were investigated. The threshold for soliton formation and the soliton composition was studied for various launching conditions of fundamental intensity imbalance and phase- mismatch configurations. The changing fundamental polarization components in the QSS with input polarization variations provided a mechanism to produce a binary all-optical switch due to spatial walk-off in the critically phase-matched geometry. The robust nature of QSS formation was compared to conventional methods for SHG. Soliton formation occurs due to strong coupling of high intensity fields focused at the entrance face of the crystal while conventional SHG methods produce higher efficiencies through weak focusing at the center of the crystal. The enhanced phase-matching bandwidth provided by QSS formation lends itself to applications where strong temperature and mechanical control are not possible. Additional applications for beam reshaping of elliptical fundamental beams were investigated. The spatial break-up of a quasi-one-dimensional plane- wave due to modulational instabilities was examined numerically and experimentally. The break-up of a highly elliptical spatial profile into a series of circular beams matched with theoretical predictions of modulational instability. Applications for pattern formation in one- and two-transverse dimensions were demonstrated. Soliton formation due to parametric instabilities was investigated at the degeneracy point for parametric amplification in KTP. A strong pump at the harmonic frequency was seeded with a weak fundamental field and QSS formation was shown to occur. The soliton formation threshold and soliton composition was studied for various detunings from phase-matching. Clamped all-optical amplification was demonstrated over a large range of input energies.

Fuerst, Russell Alexander




Microsoft Academic Search

Digital and automated photogrammetric methods and procedures developed for the collection and management of spatial data have been well introduced on archaeological applications. Recently, special tools in Spatial Information Systems (SIS) and management systems of virtual world models (VR) have been developed. Their combination can provide relevant scientists and users with a variety of possibilities for the creation of integrated

C. Ioannidis; S. Soile


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

NASA Astrophysics Data System (ADS)

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

Luo, Ji



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

NASA Technical Reports Server (NTRS)

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

Louis, Pascal; Gokhale, Arun M.



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

PubMed Central

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

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



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

USGS Publications Warehouse

Surveys collecting count data are the primary means by which abundance is indexed for birds. These counts are confounded, however, by nuisance effects including observer effects and spatial correlation between counts. Current methods poorly accommodate both observer and spatial effects because modeling these spatially autocorrelated counts within a hierarchical framework is not practical using standard statistical approaches. We propose a Bayesian approach to this problem and provide as an example of its implementation a spatial model of predicted abundance for the Cerulean Warbler (Dendroica cerulea) in the Prairie-Hardwood Transition of the upper midwestern United States. We used an overdispersed Poisson regression with fixed and random effects, fitted by Markov chain Monte Carlo methods. We used 21 years of North American Breeding Bird Survey counts as the response in a loglinear function of explanatory variables describing habitat, spatial relatedness, year effects, and observer effects. The model included a conditional autoregressive term representing potential correlation between adjacent route counts. Categories of explanatory habitat variables in the model included land cover composition and configuration, climate, terrain heterogeneity, and human influence. The inherent hierarchy in the model was from counts occurring, in part, as a function of observers within survey routes within years. We found that the percentage of forested wetlands, an index of wetness potential, and an interaction between mean annual precipitation and deciduous forest patch size best described Cerulean Warbler abundance. Based on a map of relative abundance derived from the posterior parameter estimates, we estimated that only 15% of the species' population occurred on federal land, necessitating active engagement of public landowners and state agencies in the conservation of the breeding habitat for this species. Models of this type can be applied to any data in which the response is counts, such as animal counts, activity (e.g.,nest) counts, or species richness. The most noteworthy practical application of this spatial modeling approach is the ability to map relative species abundance. The functional relationships that we elucidated for the Cerulean Warbler provide a basis for the development of management programs and may serve to focus management and monitoring on areas and habitat variables important to Cerulean Warblers.

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



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


Opinions are divided as to whether human intervention to control elephant (Loxodonta africana) population growth is desirable, partly because of elephant welfare concerns. Female contraception through immunization with porcine zona pellucida (PZP) proteins is viable. The effects of sustained use and application of the PZP vaccine on elephant behavioral and spatial responses were examined by evaluating herd ranging, fission-fusion dynamics, association patterns, and reproductive and sexual behaviors. Minimal change was anticipated as a result of long calf dependence on and association with cows, a reduced but not indefinite 0% growth rate and the known mechanism of action of PZP vaccines, and minimal expected change in resource requirements necessitating behavioral or spatial use adaptations. Although behavioral effects identified in previous hormonal contraceptive trials were evident, it was demonstrated that immunocontraception caused no prolonged behavioral, social, or spatial changes over the 11-yr study period. Individually identified elephants were monitored from 1999 to 2011. Minimal, short-term social disruption, with temporary changes to the herds' core ranges, was observed during the annual treatment events, particularly in the first three treatment years, when vaccinations were conducted exclusively from the ground. Thereafter, when vaccinations were conducted aerially, minor disruptions were confined to the morning of administration only. Despite sustained treatments resulting in demographic changes of fewer calves being born, treatments did not alter spatial range use, and no adverse interherd-intraherd relations were observed. Similarly, resource requirements did not change as calving still occurred, although in fewer numbers. It was concluded that PZP immunocontraception has no detectable behavioral or social consequences in elephants over the course of 11 yr, providing a convincing argument for the use of sustained immunocontraception in the medium to long term as an important tool for elephant management. Behavioral consequences of alternative management approaches should all receive similar scrutiny to enable managers to make informed decisions when weighing management interventions. PMID:24437086

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



Generalized Taylor-Aris dispersion in discrete spatially periodic networks: Microfluidic applications  

NASA Astrophysics Data System (ADS)

A theory is presented for the lumped parameter, convective-diffusive transport of individual, noninteracting Brownian solute particles (``macromolecules'') moving within spatially periodic, solvent-filled networks-the latter representing models of chip-based microfluidic chromatographic separation devices, as well as porous media. Using graph-theoretical techniques, the composite medium is conceptually decomposed into a network of channels (the edges) through which the solute is transported by a combination of molecular diffusion and either ``piggyback'' entrainment within a flowing solvent or an externally applied force field acting upon the solute molecules. A probabilistic choice of egress channel for a solute particle exiting the intersection (vertex) of the channels is furnished by an imperfect mixing model. A spatially periodic, Taylor-Aris-like ``method-of-moments'' scheme is applied to this transport model, leading to discrete matrix equations for computing the network-scale particle velocity vector U¯* and dispersivity dyadic Dbar* in terms of the prescribed microscale transport parameters and network geometry characterizing the basic unit cell of which the spatially periodic device is comprised. The ensuing algebraic equations governing the vertex-based, discrete unit-cell ``fields'' P?0(i) and B(i) (i=1,2,...,n), whose paradigmatic summations yield U¯* and Dbar*, constitute discrete analogs of classical continuous macrotransport phenomenological parameters, P?0(r) and B(r), with r a continuous position vector defined within the unit cell. The ease with which these discrete calculations can be performed for complex networks renders feasible parametric studies of potential microfluidic chip designs, particularly those pertinent to biomolecular separation schemes. Application of this discrete theory to the dispersion analysis of pressure-driven flow in spatially periodic serpentine microchannels is shown to accord with existing results previously derived using classical continuous macrotransport theory.

Dorfman, Kevin D.; Brenner, Howard



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


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



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

PubMed Central

Background Health professionals and authorities strive to cope with heterogeneous data, services, and statistical models to support decision making on public health. Sophisticated analysis and distributed processing capabilities over geocoded epidemiological data are seen as driving factors to speed up control and decision making in these health risk situations. In this context, recent Web technologies and standards-based web services deployed on geospatial information infrastructures have rapidly become an efficient way to access, share, process, and visualize geocoded health-related information. Methods Data used on this study is based on Tuberculosis (TB) cases registered in Barcelona city during 2009. Residential addresses are geocoded and loaded into a spatial database that acts as a backend database. The web-based application architecture and geoprocessing web services are designed according to the Representational State Transfer (REST) principles. These web processing services produce spatial density maps against the backend database. Results The results are focused on the use of the proposed web-based application to the analysis of TB cases in Barcelona. The application produces spatial density maps to ease the monitoring and decision making process by health professionals. We also include a discussion of how spatial density maps may be useful for health practitioners in such contexts. Conclusions In this paper, we developed web-based client application and a set of geoprocessing web services to support specific health-spatial requirements. Spatial density maps of TB incidence were generated to help health professionals in analysis and decision-making tasks. The combined use of geographic information tools, map viewers, and geoprocessing services leads to interesting possibilities in handling health data in a spatial manner. In particular, the use of spatial density maps has been effective to identify the most affected areas and its spatial impact. This study is an attempt to demonstrate how web processing services together with web-based mapping capabilities suit the needs of health practitioners in epidemiological analysis scenarios. PMID:22126392



Enabling OLAP in mobile environments via intelligent data cube compression techniques  

Microsoft Academic Search

The main drawbacks of handheld devices (small storage space, small size of the display screen, discontinuance of the connection\\u000a to the WLAN etc) are often incompatible with the need of querying and browsing information extracted from enormous amounts\\u000a of data which are accessible through the network. In this application scenario, data compression and summarization have a\\u000a leading role: data in

Alfredo Cuzzocrea; Filippo Furfaro; Domenico Saccà




E-print Network

work in [13] by allowing particle mobility. Such spatial birth-mobility-and-death processes can also be seen as a general- ization of the spatial birth-and-death generator, which allows for mobility: spatial birth-and-death process, spatial queueing network, mobility, regularity, ergodicity, invariant

Boyer, Edmond


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.



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


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

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



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)



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


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



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

NASA Astrophysics Data System (ADS)

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

Zhou, Lijuan; Wu, Minhua; Li, Shuang



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

SciTech Connect

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

Burley, J.B.



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

ERIC Educational Resources Information Center

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

Karatepe, Akif



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

NASA Technical Reports Server (NTRS)

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

Efron, Uzi (editor)



Construction and application of particle swarm optimization algorithm for ecological spatial data mining  

NASA Astrophysics Data System (ADS)

The research of the regional ecological environment becomes more important to regional Sustainable Development in order to achieve the harmonious relationship between the person and the nature. The advent of spatial information technologies, such as GIS, GPS and RS, have great enhanced our capabilities to collect and capture spatial data. How to discover potentially useful information and knowledge from massive amounts of spatial data is becoming a crucial project for spatial analysis and spatial decision making. Particle Swarm Optimization has a powerful ability for reasoning and semantic representation, which combined with qualitative analysis and quantitative analysis, with prior knowledge and observed data, and provides an effective way to spatial data mining. This paper focuses on construction and learning a Particle Swarm Optimization model for spatial data mining. Firstly, the theory of spatial data mining is introduced and the characteristics of Particle Swarm Optimization are discussed. A framework and process of spatial data mining is proposed. Then we construct a Particle Swarm Optimization model for spatial data mining with the given dataset. The research area is focused on the distribution of pollution sources in Wuhan City. The experimental results demonstrate the feasibility and practical of the proposed approach to spatial data mining. Finally, draw a conclusion and show further avenues for research. Through the empirical study, it has been proved that Particle Swarm Optimization algorithm is feasible and the conclusion can provide instruction for local environmental planning.

Fu, ZhongLiang; Wan, Bin



Theory and application for retrieval and fusion of spatial and temporal quantitative information from complex natural environment  

Microsoft Academic Search

This paper briefly presents the research progress of the State Major Basic Research Project 2001CB309400, “Theory and Application\\u000a for Retrieval and Fusion of Spatial and Temporal Quantitative Information from Complex Natural Environment”. Based on the\\u000a rapid advancement of synthetic aperture radar (SAR) imagery technology, information theory of fully polarimetric scattering\\u000a and applications in polarimetric SAR remote sensing are developed. To

Yaqiu Jin




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...


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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

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

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



Fine-pitch high-efficiency spatial optical modulator for mobile display applications  

NASA Astrophysics Data System (ADS)

Diffractive spatial optical modulators (SOM) with fine pitch pixel array were introduced for the mobile applications of laser projection display which requires the small volume, low power consumption and high optical efficiency. Micromechanical designs of piezoelectric (PZT) actuator and mirror ribbon structure were optimized for small volume, but keeping the same level of the other performance. Even though the same design rule and fabrication equipment were used for 10 um pitch SOM and 16 um pitch SOM, the optical efficiency of the fine pitch SOM was 78 % for the 0th order diffraction and is better than that of 16 um pitch SOM (73%). The full on/off contrast ratio has no difference between 10 um pitch and 16 um pitch SOM. All the optical characteristics coincide well with the theoretical estimations. High displacement of 500nm, which is enough to modulate the three Red, Green and Blue colors were achieved by the control of the thicknesses and stresses of constituent structural layers. It was found that the stress of Pt/PZT/Pt actuating layer was the main parameter affecting the initial gap height of the ribbon and also its displacement. For improving the optical properties of the SOM devices, the required ribbon-flatness could be achieved by applying a stress gradient on the SiN layer to compensate for the stress unbalance between Al mirror and SiN supprting layer. The temperature sensitive characteristics of the SOM device, which degrades the image quality, could be minimized by a mechanical compensation method using a thermal expansion effect of Si substrates. This concept could be applied in most of the bridge type MEMS structure. The most critical parameter which limit the SOM device lifetime was found to be the ribbon displacement degradation. By using a temperature accelerating lifetime measurement method based on the displacement degradation the estimated lifetime was more than 4,000 hrs and is of acceptable level in the mobile application. In short, the developed fine pitch SOM device, for making small volume of optical module, has sufficient response time and ribbon displacement for modulating the red, blue and green colors with one SOM chip and is suitable for high quality embedded laser projection displays. Optical module with VGA is successfully demonstrated for its potential applications in mobile laser projection display such as a embed projection cellular phone.

Song, Jong Hyeong; Yun, Sang Kyeong; Kim, Hee Yeoun; An, Seungdo; Park, Heung Woo; Choi, Yoon Joon; Yurlov, Victor; Lapchuk, Anatoliy; Yang, Chung Mo; Lee, Sung Jun; Jang, Jae Wook; Lee, Ki Un; Woo, Ki Suk; Bourim, El M.



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




Estimating Treatment Effects from Spatial Policy Experiments: An Application to Ugandan Microfinance  

Microsoft Academic Search

This paper demonstrates a method for estimating treatment effects in spatial tests, utilizing a second control group to measure unexplained spatial phenomena. The technique is implemented on two innovations in Ugandan microfinance, and we measure the ways in which concurrent shocks such as an Ebola outbreak and a contentious presidential election altered outcomes differentially across regions. By correcting for this

Craig McIntosh



Spatial correlations of monthly rainfall: Applications in climatology and weather modification experiments  

Microsoft Academic Search

Spatial correlations based on monthly rainfall totals from northwest Georgia for the period 1949--77 are studied. This work, a part of the Meteorological Effects of Thermal Energy Releases (METER) Program, determines natural variability rainfall trends and assists the field studies of potential precipitation effects of the Bowen Electric Generating Plant near Cartersville, Georgia. The spatial correlations, based on the overall

A. A. N. Patrinos; N. C. J. Chen; R. L. Miller



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

ERIC Educational Resources Information Center

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

Cepeda-Cuervo, Edilberto; Núñez-Antón, Vicente



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


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



Towards the geometric optimization of potential field models - A new spatial operator tool and applications  

NASA Astrophysics Data System (ADS)

We present a new method for automated geometric modifications of potential field models. Computational developments and the increasing amount of available potential field data, especially gradient data from the satellite missions, lead to increasingly complex models and integrated modelling tools. Editing of these models becomes more difficult. Our approach presents an optimization tool that is designed to modify vertex-based model geometries (e.g. polygons, polyhedrons, triangulated surfaces) by applying spatial operators to the model that use an adaptive, on-the-fly model discretization. These operators deform the existing model via vertex-dragging, aiming at a minimized misfit between measured and modelled potential field anomaly. The parameters that define the operators are subject to an optimization process. This kind of parametrization provides a means for the reduction of unknowns (dimensionality of the search space), allows a variety of possible modifications and ensures that geometries are not destroyed by crossing polygon lines or punctured planes. We implemented a particle swarm optimization as a global searcher with restart option for the task of finding optimal operator parameters. This approach provides us with an ensemble of model solutions that allows a selection and geologically reasonable interpretations. The applicability of the tool is demonstrated in two 2D case studies that provide models of different extent and with different objectives. The first model is a synthetic salt structure in a horizontally layered background model. Expected geometry modifications are considerably small and localized and the initial models contain rather little information on the intended salt structure. A large scale example is given in the second study. Here, the optimization is applied to a sedimentary basin model that is based on seismic interpretation. With the aim to evaluate the seismically derived model, large scale operators are applied that mainly cause depth adjustments to the model horizons.

Haase, Claudia; Götze, Hans-Jürgen



Application of Data Fusion in the Production and Updating of Spatial Data  

NASA Astrophysics Data System (ADS)

The increasing spatial data provide abundant material for data fusion, and the purpose of the paper is to apply data fusion into the production and updating of spatial data. After outlining the general framework and workflow, the processing contents and methods are specified in sequence. Facing various spatial data from different sources, how to design proper data fusion scheme is the toppriority problem. The method of analyzing and assessing various spatial data is introduced referring to images, which is shown by concrete examples. Then the technical workflow of multi-source data integration is present to eliminate differences and relevant contents are also specified. After building the relationships of homologous entities through spatial data matching, the data fusion which is similar to cartographic generalization in essence can be implemented. Different ways of updating spatial data is introduced to keep the currency of existing data. At last, the spatial data with good quality can be obtained. The efficient and reliability of the methodology in this paper has been proved through practical production.

Chen, H.; Sun, Q.; Xu, L.; Xiong, Z.



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

NASA Technical Reports Server (NTRS)

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

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



Application of spatial Poisson process models to air mass thunderstorm rainfall  

NASA Technical Reports Server (NTRS)

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

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



The Dual Spatial Autoregressive Probit Model with an Application to the 2001 Congressional Farm Bill  

Microsoft Academic Search

Political economy models of congressional voting usually rely on standard econometric techniques, such as the probit or logit models. These techniques ignore any spatial externality in voting outcomes that may be geographically correlated across space, a phenomenon

Donald J. Lacombe; Garth J. Holloway; Timothy M. Shaughnessy



December 2006 Spatial Autocorrelation and Pseudoreplication 107 Practices and Applications in Fire Ecology  

E-print Network

fire ecology researchers. Key Words: nearness, experimental design, ecology, landscape Ecology SPATIAL AUTOCORRELATION AND PSEUDOREPLICATION IN FIRE ECOLOGY Amanda L. Bataineh1 , Brian P of Forestry and Agriculture, Stephen F. Austin State University 2 Department of Natural Resources

Hung, I-Kuai


Estimation of spatial-temporal point process models using the (stochastic) Expectation Maximization algorithm and its application to California earthquakes  

Microsoft Academic Search

We explore the use of the Expectation Maximization (EM) algorithm as well as its stochastic version for estimating the parameters of spatial-temporal point process models, in particular the Epidemic-Type Aftershock Sequence (ETAS) model (Ogata 1988, 1998). We present situations in which this algorithm performs better than directly maximizing the log-likelihood function and show an application to earthquake occurrence data from

Alejandro Veen; Frederic Paik Schoenberg


Spatial stochastic processes for yield and reliability management with applications to nano electronics  

E-print Network

yield modeling and the extrinsic reliabil- ity estimation model. New yield models of integrated circuits based on the spatial point process are established. The defect density which varies according to location on the wafer is modeled by the spatial... nonhomogeneous Poisson process. And, in order to capture the variations in defect patterns between wafers, a random coe?- cient model and model-based clustering are applied. Model-based clustering is also applied to the fabrication process control for detecting...

Hwang, Jung Yoon



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


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



Spatial Polarimetric Time-Frequency Distributions and Applications to Direction-of-Arrival Estimation  

Microsoft Academic Search

Time-frequency distributions (TFDs) have evolved to be a powerful technique for nonstationary signal analysis and synthesis. With the use of a multi-sensor array, spatial time-frequency distributions (STFDs) have been developed and successfully applied to high-resolution direction-of-arrival (DOA) estimation and blind recovery of the source waveforms. In this paper, the polarimetric dimension is introduced to the STFDs resulting in the spatial

Yimin Zhang; Moeness G. Amin; Baha A. Obeidat


Persistence analysis in geophysical spatial series: an application to well log data  

NASA Astrophysics Data System (ADS)

Fractal geometry is the field of Mathematics that studies the properties and behavior of fractals. It was already applied to several areas of Science, explaining many situations that cannot be described by classical geometry. A fractal is a geometric object that can be divided into several parts, each one similar to the original object. Fractal geometry has been used frequently to characterize and describe natural models. Its applications range from microscopic dimensions to the understanding of macroscopic processes. Many geophysical variables seem to have a scale behavior, which means that their power spectrum, P(f), seem to be proportional to some frequency f, that is, ln[P(f)] = - b ln(f), where b is called the spectral exponent. Following this principle, we propose to study a set of well log data, collected in the Jequitinhonha basin (Brazil), through the methods of spectral analysis and re-scaled analysis. When the spectral exponent varies from 0.5 to 1.5, the physical property is said to have a 1/f noise. One method to verify the long range persistence is through the re-scaled (R/S) analysis, with computes the Hurst coefficient H. H and the exponent b are related by bcum = 2H + 1, where bcum is cumulative spectral exponent of the sequence with exponent b. The spatial series are the following well data: acoustic velocity, gamma ray, induction deep resistivity, porosity, density, resistivity average, and spontaneous potential. For each parameter, we computed the spectral exponent b, and the coefficient H, attesting the variability of the available data. The results for H were coherent with other works mentioned in the literature. We obtained 0.6 < H < 0.9 for both methods, in such a way that all the parameters behave as persistent. The importance of such study is to show that different methods provided the same results, which is a significant fact for complex systems. The knowledge of H also provides the computation of the fractal dimension, as well as to understand the complexity of layer sedimentation phenomenon.

Bassrei, A.



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



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

USGS Publications Warehouse

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

Preston, Stephen D.; Brakebill, John W.



Unsupervised spatial event detection in targeted domains with applications to civil unrest modeling.  


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

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



Bayesian Modeling of Multivariate Spatial Binary Data with applications to Dental Caries  

PubMed Central

SUMMARY Dental research gives rise to data with potentially complex correlation structure. Assessments of dental caries yields a binary outcome indicating the presence or absence of caries experience for each surface of each tooth in a subject’s mouth. In addition to this nesting, caries outcome exhibit spatial structure among neighboring teeth. We develop a Bayesian multivariate model for spatial binary data using random effects autologistic regression that controls for the correlation within tooth surfaces and spatial correlation among neighboring teeth. Using a sample from a clinical study conducted at the Medical University of South Carolina, we compare this autologistic model with covariates to alternative models to demonstrate the improvement in predictions and also to assess the effects of covariates on caries experience. PMID:19902498

Bandyopadhyay, Dipankar; Reich, Brian J.; Slate, Elizabeth



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

PubMed Central

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

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



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


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

Sparks, Corey S



A methodology for modelling and retrieving satellite images basing on spatial knowledge: application to natural risks  

NASA Astrophysics Data System (ADS)

In this paper, we present a methodology for modelling and retrieving satellite images basing on their spatial knowledge. The main idea of our approach is that the use of spatial knowledge, reasoning and inference technique, can contribute to deduce the susceptibility of the scene at natural risks (erosion, flooding, fires, etc.). Our methodology takes in input a set of multi-sensor images representing a scene. It contains four modules: (1) Modelling of the scene, (2) fusion of image annotations, (3) similar case retrieval, and (4) reasoning and interpretation.

Messaoudi, Wassim; Farah, Imed Riadh; Ghezala, Henda Ben; Solaiman, Basel




E-print Network

) involve discrete responses in a temporal and spatial context. It is especially true for analysis conditions and other, socio-economic factors: land owners make development decisions based on their knowledge relationships in ordered categorical data. This paper demonstrates how this model can be applied to the analysis

Kockelman, Kara M.


Unsupervised soil drainage classification and mapping through the application of spatial and nonspatial methods  

Microsoft Academic Search

The accuracy of a soil map is strongly related to the level of spatial precision of its mapped properties, such as soil drainage quality, which are increasingly needed for effective soil and water management plan implementations in agriculture and natural resource management. Multivariate logistic regression analysis, geostatistics, and GIS were applied to the SSURGO soil survey data (NRCS) and continuous

Rifat Akis



Bivariate B-splines and its Applications in Spatial Data Analysis  

E-print Network

In the field of spatial statistics, it is often desirable to generate a smooth surface for a region over which only noisy observations of the surface are available at some locations, or even across time. Kriging and kernel estimations are two...

Pan, Huijun 1987-



Extending Data Mining for Spatial Applications: A Case Study in Predicting Nest Locations  

E-print Network

, transportation, public health, business lo­ gistics, travel and tourism. Classical data mining al­ gorithms [7 in the development of spatial model for the nesting locations of a marsh­nesting bird species [15, 16]. We will use(Darr and Stubble) located on the shores of Lake Erie in Ohio. A uniform grid was imposed on the wetlands

Shekhar, Shashi


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



Spatial Lasso with Applications to GIS Model Selection Hsin-Cheng Huang  

E-print Network

to a modification of the Lasso procedure. The LARS algorithm, which can be used in a fast implementation of Lasso include information on geology, topography, weather and climate, ownership, political administration, land to a modification of the Lasso procedure that we call spatial Lasso. The model and the implementation of standard


Digital Hydrologic Networks Supporting Applications Related to Spatially Referenced Regression Modeling1  

PubMed Central

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

Brakebill, JW; Wolock, DM; Terziotti, SE



Regional and Temporal Variation in Methamphetamine-Related Incidents: Applications of Spatial and Temporal Scan Statistics  

PubMed Central

Introduction This investigation utilized spatial scan statistics, geographic information systems and multiple data sources to assess spatial clustering of statewide methamphetamine-related incidents. Temporal and spatial associations with regulatory interventions to reduce access to precursor chemicals (pseudoephedrine) were also explored. Methods Four statewide data sources were utilized including regional poison control center statistics, fatality incidents, methamphetamine laboratory seizures, and hazardous substance releases involving methamphetamine laboratories. Spatial clustering of methamphetamine incidents was assessed using SaTScan™. SaTScan™ was also utilized to assess space-time clustering of methamphetamine laboratory incidents, in relation to the enactment of regulations to reduce access to pseudoephedrine. Results Five counties with a significantly higher relative risk of methamphetamine-related incidents were identified. The county identified as the most likely cluster had a significantly elevated relative risk of methamphetamine laboratories (RR=11.5), hazardous substance releases (RR=8.3), and fatalities relating to methamphetamine (RR=1.4). A significant increase in relative risk of methamphetamine laboratory incidents was apparent in this same geographic area (RR=20.7) during the time period when regulations were enacted in 2004 and 2005, restricting access to pseudoephedrine. Subsequent to the enactment of these regulations, a significantly lower rate of incidents (RR 0.111, p=0.0001) was observed over a large geographic area of the state, including regions that previously had significantly higher rates. Conclusions Spatial and temporal scan statistics can be effectively applied to multiple data sources to assess regional variation in methamphetamine-related incidents, and explore the impact of preventive regulatory interventions. PMID:19225949

Sudakin, Daniel L.



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

PubMed Central

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

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



High-fidelity spatially resolved multiphoton counting for quantum imaging applications  

E-print Network

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

Radoslaw Chrapkiewicz; Wojciech Wasilewski; Konrad Banaszek



Spatial MAC in MIMO Communications and its Application to Underlay Cognitive Radio  

E-print Network

We propose a learning technique for MIMO secondary users (SU) to spatially coexist with Primary Users (PU). By learning the null space of the interference channel to the PU, the SU can utilize idle degrees of freedom that otherwise would be unused by the PU. This learning process does not require any handshake or explicit information exchange between the PU and the SU. The only requirement is that the PU broadcasts a periodic beacon that is a function of its noise plus interference power, through a low rate control channel. The learning process is based on energy measurements, independent of the transmission schemes of both the PU and SU, i.e. independent of their modulation, coding etc.. The proposed learning technique also provides a novel spatial division multiple access mechanism for equal-priority MIMO users sharing a common channel that highly increases the spectrum utilization compared to time based or frequency multiple access.

Noam, Yair



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


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

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



Workflow-based Spatial Modeling Environment and its application in food provisioning services of grassland ecosystem  

Microsoft Academic Search

Focusing on the topic of model integration, we develop a Workflow-based Spatial Modeling Environment (WF-SME) which enables scientists and modeling users easy to design and create of complex systems models through a drag-drop operation or editing mathematical formula in model constructor. WF-SME, a visual integrated modeling environment is mainly used for the rapid realization of model dynamic integration, in which

Yimin Lu; Tianxiang Yue; Chenliang Wang; Qinmin Wang



A spatial\\/spectral protocol for quality assurance of decompressed hyperspectral data for practical applications  

Microsoft Academic Search

A detailed spatial\\/spectral protocol to test the influence of compressed-decompressed on the hyperspectral image data is presented. The proposed scheme is evaluated by applying an hybrid algorithm (LCT and SPHIT) on AISA-Dual hyperspectral images. For the purpose of reliable thematic results, the preservation and recovering of reflectance spectral features should be on the main concern. Therefore, this protocol contains three

Anna Brook; Eyal Ben-Dor



Spatial variation of residual stresses in a welded pipe for high temperature applications  

Microsoft Academic Search

Measurements of residual macro-stresses have been undertaken in a feature multipass circumferential single V butt-weld made from a P91 ferritic steel pipe over different spatial depths: (i) ?10?m by X-ray diffraction, (ii) ?1mm by incremental centre-hole drilling and (iii) through wall section using deep-hole drilling. The ability to make near-surface X-ray residual stress measurements on as-oxidised surfaces has been demonstrated

G. Hilson; S. Simandjuntak; P. E. J. Flewitt; K. R. Hallam; M. J. Pavier; D. J. Smith



Practical definition of territory and its application to the spatial distribution of voles  

Microsoft Academic Search

The utility of the definition of territory proposed by Davies (1978) (individual animals or groups are spaced out more than\\u000a would be expected from a random occupation of suitable habitats) was tested by applying it to an analysis of spacing behavior\\u000a in voles,Clethrionomys rufocanus bedfordiae (Thomas). The examination of the Nearest Neighbor Distance and spatial distribution of home range suggested

Takashi Saitoh



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


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

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



A Bayesian normal mixture accelerated failure time spatial model and its application to prostate cancer.  


In the United States, prostate cancer is the third most common cause of death from cancer in males of all ages, and the most common cause of death from cancer in males over age 75. It has been recognized that the incidence of the prostate cancer is high in African Americans, and its occurrence and progression may be impacted by geographical factors. In order to investigate the spatial effects and racial disparities for prostate cancer in Louisiana, in this article we propose a normal mixture accelerated failure time spatial model, which does not require the proportional hazards assumption and allows the multi-model distribution to be modeled. The proposed model is estimated with a Bayesian approach and it can be easily implemented in WinBUGS. Extensive simulations show that the proposed model provides decent flexibility for a variety of parametric error distributions. The proposed method is applied to 2000-2007 Louisiana prostate cancer data set from the Surveillance, Epidemiology and End Results Program. The results reveal the possible spatial pattern and racial disparities for prostate cancer in Louisiana. PMID:23117407

Wang, Songfeng; Zhang, Jiajia; Lawson, Andrew B



Spatially aware expectation maximization (SpAEM): application to prostate TRUS segmentation  

NASA Astrophysics Data System (ADS)

In this paper we introduce Spatially Aware Expectation Maximization (SpAEM), a new parameter estimation method which incorporates information pertaining to spatial prior probability into the traditional expectation- maximization framework. For estimating the parameters of a given class, the spatial prior probability allows us to weight the contribution of any pixel based on the probability of that pixel belonging to the class of interest. In this paper we evaluate SpAEM for the problem of prostate capsule segmentation in transrectal ultrasound (TRUS) images. In cohort of 6 patients, SpAEM qualitatively and quantitatively outperforms traditional EM in distinguishing the foreground (prostate) from background (non-prostate) regions by around 45% in terms of the Sorensen Dice overlap measure, when compared against expert annotations. The variance of the estimated parameters measured via Cramer-Rao Lower Bound suggests that SpAEM yields unbiased estimates. Finally, on a synthetic TRUS image, the Cramer-Von Mises (CVM) criteria shows that SpAEM improves the estimation accuracy by around 51% and 88% for prostate and background, respectively, as compared to traditional EM.

Orooji, Mahdi; Sparks, Rachel; Bloch, B. Nicolas; Feleppa, Ernest; Barratt, Dean; Madabhushi, Anant



Spatial modeling and dynamics of a photovoltaic generator for renewable energy application.  

E-print Network

??Photovoltaic systems alongside energy storage systems are a recognized distributed generation (DG) technology deployed in stand-alone and grid connected system for urban and rural applications.… (more)

Bello, Mashood Mobolaji.



[Effects of wheat-oilseed rape intercropping and methyl salicylate application on the spatial distributions of Sitobion avenae and its main natural enemies].  


A field investigation was conducted on the spatial distributions of Sitobion avenae and its main natural enemies under wheat-oilseed rape intercropping and methyl salicylate application. With the development of wheat plant, an alternation from aggregation to uniform was observed in the spatial distribution of S. avenae under the intercropping and methyl salicylate application, being more obvious under the interaction of the two practices. The spatial distribution of S. avenae natural enemies was in accordance with that of the aphid. These results could be used for the reference of sampling investigation and forecast of wheat aphid and its natural enemies in field. PMID:23173471

Dong, Jie; Liu, Ying-Jie; Wang, Guang; Liu, Yong



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

NASA Astrophysics Data System (ADS)

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 mm2). 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.

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.



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

NASA Astrophysics Data System (ADS)

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

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



Application of spatial EOF and multivariate time series model for evaluating agricultural drought vulnerability in Korea  

NASA Astrophysics Data System (ADS)

This study proposed a methodology using the empirical orthogonal function (EOF) and multivariate time series model for the analysis of drought both in time and space. The methodology proposed was then applied to evaluate the vulnerability of agricultural drought of major river basins in Korea. First, the three-month SPI data from 59 rain gauge stations over the Korean Peninsula were analyzed by deriving and spatially characterizing the EOFs. The shapes of major estimated EOFs were found to well reflect the observed spatial pattern of droughts. Second, the coefficient time series of estimated EOFs were then fitted by a multivariate time series model to generate the SPI data for 10,000 years, which were used to derive the annual maxima series of areal average drought severity over the Korean Peninsula. These annual maxima series were then analyzed to determine the mean drought severity for given return periods. Four typical spatial patterns of drought severity could also be selected for those return periods considered. This result shows that the southern part of the Korean Peninsula is most vulnerable to drought than the other parts. Finally, the agricultural drought vulnerability was evaluated by considering the potential water supply from dams. In an ideal case, when all the maximum dam storage was assumed to be assigned to agriculture, all river basins in Korea were found to have the potential to overcome a 30-year drought. However, under more realistic conditions considering average dam storage and water allocation priorities, most of the river basins could not overcome a 30-year drought.

Kim, Dae Ha; Yoo, Chulsang; Kim, Tae-Woong



Pattern classification of fMRI data: applications for analysis of spatially distributed cortical networks.  


The field of fMRI data analysis is rapidly growing in sophistication, particularly in the domain of multivariate pattern classification. However, the interaction between the properties of the analytical model and the parameters of the BOLD signal (e.g. signal magnitude, temporal variance and functional connectivity) is still an open problem. We addressed this problem by evaluating a set of pattern classification algorithms on simulated and experimental block-design fMRI data. The set of classifiers consisted of linear and quadratic discriminants, linear support vector machine, and linear and nonlinear Gaussian naive Bayes classifiers. For linear discriminant, we used two methods of regularization: principal component analysis, and ridge regularization. The classifiers were used (1) to classify the volumes according to the behavioral task that was performed by the subject, and (2) to construct spatial maps that indicated the relative contribution of each voxel to classification. Our evaluation metrics were: (1) accuracy of out-of-sample classification and (2) reproducibility of spatial maps. In simulated data sets, we performed an additional evaluation of spatial maps with ROC analysis. We varied the magnitude, temporal variance and connectivity of simulated fMRI signal and identified the optimal classifier for each simulated environment. Overall, the best performers were linear and quadratic discriminants (operating on principal components of the data matrix) and, in some rare situations, a nonlinear Gaussian naïve Bayes classifier. The results from the simulated data were supported by within-subject analysis of experimental fMRI data, collected in a study of aging. This is the first study that systematically characterizes interactions between analysis model and signal parameters (such as magnitude, variance and correlation) on the performance of pattern classifiers for fMRI. PMID:24705202

Yourganov, Grigori; Schmah, Tanya; Churchill, Nathan W; Berman, Marc G; Grady, Cheryl L; Strother, Stephen C



Automatic extraction of watershed characteristics using spatial analysis techniques with application to groundwater mapping  

NASA Astrophysics Data System (ADS)

Spatial analysis techniques were developed using a raster-based image processing system to derive geometric and morphologic characteristics of watersheds from a digital elevation model. The watershed data layers were overlaid with digital soils information for two 7 {1'}/{2} quadrangles in the Cascade Mountains of Washington. The data layers were then integrated with a ground-water prediction model and maps of groundwater level zones were prepared from the digital data sets. This information can be useful in assessing the stability of slopes in landslide hazard prediction.

Benosky, Christopher P.; Merry, Carolyn J.



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

NASA Astrophysics Data System (ADS)

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

Tasser, Erich; Wohlfahrt, Georg



Spatial polarimetric time-frequency distributions and applications to direction-of-arrival estimation  

NASA Astrophysics Data System (ADS)

Time-frequency distributions (TFDs) have evolved to be a powerful technique for nonstationary signal analysis and synthesis. With the use of a multi-sensor array, spatial time-frequency distributions (STFDs) have been developed and successfully applied to high-resolution direction-of-arrival (DOA) estimation and blind recovery of the source waveforms. In this paper, the polarimetric dimension is introduced to the STFDs resulting in the spatial polarimetric time-frequency distributions (SPTFDs) as a platform for the processing of non-stationary polarized signals. In the SPTFD platform, polarized signals are decomposed (projected) into two orthogonal polarization components, such as horizontal and vertical, and later processed in a manner where their polarization characteristics are exploited. This empowers the STFDs with additional degrees of freedom and improves the robustness of the signal and noise subspaces, and therefore, serving to enhance DOA estimation, signal recovery, and source separation performance. To demonstrate the advantages of the SPTFDs, the polarimetric time-frequency MUSIC (PTF-MUSIC) method for DOA estimation is proposed based on the SPTFD platform and is shown to outperform the time-frequency, polarimetric, and conventional MUSIC methods.

Zhang, Yimin; Amin, Moeness G.; Obeidat, Baha A.



Temporal and spatial variation of surface reaction rates in porous media: Applications to silicate weathering  

NASA Astrophysics Data System (ADS)

Percolation theory provides a promising framework for modeling transport in heterogeneous porous media, including hydraulic and electrical conductivity, air permeability, gas diffusivity, and solute transport. Using percolation concepts (e.g., critical path analysis, fractal scaling of percolation clusters, and cluster statistics), we developed a physically-based model for predicting solute transport. Our model predicted spatial solute distributions as a function of time, and arrival time distributions as a function of system size. Our solute transport predictions gave good matches to a wide range of experiments. We now apply our solute transport model to silicate weathering. We assume that surface chemical reactions are at equilibrium at the scale of a single pore, but that at larger length scales, reactions are limited by transport of reactants or products. Using results from published field experiments, we find that the temporal and spatial dependence derived from solute velocity successfully predicts the measured time- and length-dependence of reaction rates and weathering of silicate minerals over a wide range of time and length scale. A similar analysis of lab experiments (uranium breakthrough curves measured in two short and long columns from the Hanford site) indicates that normalized reaction rate versus normalized time follow 2D invasion and 3D random percolation.

Ghanbarian, B.; Hunt, A. G.; Skinner, T. E.; Ewing, R. P.



Geo-spatial Service and Application based on National E-government Network Platform and Cloud  

NASA Astrophysics Data System (ADS)

With the acceleration of China's informatization process, our party and government take a substantive stride in advancing development and application of digital technology, which promotes the evolution of e-government and its informatization. Meanwhile, as a service mode based on innovative resources, cloud computing may connect huge pools together to provide a variety of IT services, and has become one relatively mature technical pattern with further studies and massive practical applications. Based on cloud computing technology and national e-government network platform, "National Natural Resources and Geospatial Database (NRGD)" project integrated and transformed natural resources and geospatial information dispersed in various sectors and regions, established logically unified and physically dispersed fundamental database and developed national integrated information database system supporting main e-government applications. Cross-sector e-government applications and services are realized to provide long-term, stable and standardized natural resources and geospatial fundamental information products and services for national egovernment and public users.

Meng, X.; Deng, Y.; Li, H.; Yao, L.; Shi, J.



Spatially adaptive multiwavelet representations on unstructured grids with applications to multidimensional computational modeling  

E-print Network

In this thesis, we develop wavelet surface wavelet representations for complex surfaces, with the goal of demonstrating their potential for 3D scientific and engineering computing applications. Surface wavelets were ...

Castrillón Candás, Julio E. (Julio Enrique)



Testing for spatial correlation and semiparametric spatial modeling of binary outcomes with application to aberrant crypt foci in colon carcinogenesis experiments  

E-print Network

In an experiment to understand colon carcinogenesis, all animals were exposed to a carcinogen while half the animals were also exposed to radiation. Spatially, we measured the existence of aberrant crypt foci (ACF), namely morphologically changed...

Apanasovich, Tatiyana Vladimirovna



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


[Application of spatially explicit landscape model in soil loss study in Huzhong area].  


Universal Soil Loss Equation (USLE) has been widely used to estimate the average annual soil loss. In most of the previous work on soil loss evaluation on forestland, cover management factor was calculated from the static forest landscape. The advent of spatially explicit forest landscape model in the last decade, which explicitly simulates the forest succession dynamics under natural and anthropogenic disturbances (fire, wind, harvest and so on) on heterogeneous landscape, makes it possible to take into consideration the change of forest cover, and to dynamically simulate the soil loss in different year (e.g. 10 years and 20 years after current year). In this study, we linked a spatially explicit landscape model (LANDIS) with USLE to simulate the soil loss dynamics under two scenarios: fire and no harvest, fire and harvest. We also simulated the soil loss with no fire and no harvest as a control. The results showed that soil loss varied periodically with simulation year, and the amplitude of change was the lowest under the control scenario and the highest under the fire and no harvest scenario. The effect of harvest on soil loss could not be easily identified on the map; however, the cumulative effect of harvest on soil loss was larger than that of fire. Decreasing the harvest area and the percent of bare soil increased by harvest could significantly reduce soil loss, but had no significant effects on the dynamic of soil loss. Although harvest increased the annual soil loss, it tended to decrease the variability of soil loss between different simulation years. PMID:15624815

Xu, Chonggang; Hu, Yuanman; Chang, Yu; Li, Xiuzhen; Bu, Renchang; He, Hongshi; Leng, Wenfang



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



Scaling of spatial snow depth distribution parameters for large-scale model applications  

NASA Astrophysics Data System (ADS)

Snow depth distribution is extremely heterogeneous in mountainous terrain where the snow cover is typically influenced by large spatial gradients of incident radiation, precipitation and wind. Small-scale snow depth variations play a key role in large-scale models such as hydrologic catchment or land-surface models. Due to computational constraints, small-scale distributed modeling is, in general, rarely feasible for large regions. However, information about small-scale (sub-grid) snow coverage is essential for instance to accurately represent snow melt rates for large grid sizes. Past research has shown that for rather homogeneous landscape units the pre-melt spatial distribution of snow depth can be approximated by a log-normal distribution. However, this may no longer be valid for snow distributions over landscape units covering complex terrain. Seasonally recurring snow accumulation patterns have been reported, mostly shaped by precipitation, radiation and wind. Which process dominates, strongly depends on the considered scale. We focus on large heterogeneous landscape units on the order of a few kilometers, typically employed by hydrologic and land-surface models. In order to characterize the impact of topographic parameters on pre-melt sub grid snow depth distribution, we analyzed a new, highly resolved data set acquired at peak of winter. Snow depth data with 2 m horizontal resolution was obtained from an opto-electronic scanning data set (Sensor ADS 80, Leica Geosystems) in a large catchment located above Davos, in the eastern Swiss Alps. Sub-grid snow distribution parameters were found to scale with topographic descriptors such as mean slope and standard deviation of the summer digital elevation model. Our results suggest that parameterizations of the snow-covered fraction can be enhanced if terrain parameters are included.

Helbig, Nora; Magnusson, Jan; Jonas, Tobias



Development and application of an instrument for spatially resolved Seebeck coefficient measurements  

NASA Astrophysics Data System (ADS)

The Seebeck coefficient is a key indicator of the majority carrier type (electrons or holes) in a material. The recent trend toward the development of combinatorial materials research methods has necessitated the development of a new high-throughput approach to measuring the Seebeck coefficient at spatially distinct points across any sample. The overall strategy of the high-throughput experiments is to quickly identify the region of interest on the sample at some expense of accuracy, and then study this region by more conventional techniques. The instrument for spatially resolved Seebeck coefficient measurements reported here relies on establishing a temperature difference across the entire compositionally graded thin-film and consecutive mapping of the resulting voltage as a function of position, which facilitates the temperature-dependent measurements up to 400 °C. The results of the designed instrument are verified at ambient temperature to be repeatable over 10 identical samples and accurate to within 10% versus conventional Seebeck coefficient measurements over the -100 to +150 ?V/K range using both n-type and p-type conductive oxides as test cases. The developed instrument was used to determine the sign of electrical carriers of compositionally graded Zn-Co-O and Ni-Co-O libraries prepared by combinatorial sputtering. As a result of this study, both cobalt-based materials were determined to have p-type conduction over a broad single-phase region of chemical compositions and small variation of the Seebeck coefficient over the entire investigated range of compositions and temperature.

Zakutayev, Andriy; Luciano, Frank J.; Bollinger, Vincent P.; Sigdel, Ajaya K.; Ndione, Paul F.; Perkins, John D.; Berry, Joseph J.; Parilla, Philip A.; Ginley, David S.



Christou, C., Jones, K., Pitta-Pantazi, D., Pittalis, M., Mousoulides, N., Matos, J.F., Sendova, E., Zachariades, T., & Boytchev, P. (2007), Developing student spatial ability with 3D software applications. Paper presented at the 5th  

E-print Network

., Zachariades, T., & Boytchev, P. (2007), Developing student spatial ability with 3D software applications), Larnaca, Cyprus, 22-26 Feb 2007. 1 DEVELOPING STUDENT SPATIALABILITY WITH 3D SOFTWARE APPLICATIONS probably hinder the development of many of the 3D spatial abilities identified in the research literature


Natural, persistent oscillations in a spatial multi-strain disease system with application to dengue.  


Many infectious diseases are not maintained in a state of equilibrium but exhibit significant fluctuations in prevalence over time. For pathogens that consist of multiple antigenic types or strains, such as influenza, malaria or dengue, these fluctuations often take on the form of regular or irregular epidemic outbreaks in addition to oscillatory prevalence levels of the constituent strains. To explain the observed temporal dynamics and structuring in pathogen populations, epidemiological multi-strain models have commonly evoked strong immune interactions between strains as the predominant driver. Here, with specific reference to dengue, we show how spatially explicit, multi-strain systems can exhibit all of the described epidemiological dynamics even in the absence of immune competition. Instead, amplification of natural stochastic differences in disease transmission, can give rise to persistent oscillations comprising semi-regular epidemic outbreaks and sequential dominance of dengue's four serotypes. Not only can this mechanism explain observed differences in serotype and disease distributions between neighbouring geographical areas, it also has important implications for inferring the nature and epidemiological consequences of immune mediated competition in multi-strain pathogen systems. PMID:24204241

Lourenço, José; Recker, Mario



Natural, Persistent Oscillations in a Spatial Multi-Strain Disease System with Application to Dengue  

PubMed Central

Many infectious diseases are not maintained in a state of equilibrium but exhibit significant fluctuations in prevalence over time. For pathogens that consist of multiple antigenic types or strains, such as influenza, malaria or dengue, these fluctuations often take on the form of regular or irregular epidemic outbreaks in addition to oscillatory prevalence levels of the constituent strains. To explain the observed temporal dynamics and structuring in pathogen populations, epidemiological multi-strain models have commonly evoked strong immune interactions between strains as the predominant driver. Here, with specific reference to dengue, we show how spatially explicit, multi-strain systems can exhibit all of the described epidemiological dynamics even in the absence of immune competition. Instead, amplification of natural stochastic differences in disease transmission, can give rise to persistent oscillations comprising semi-regular epidemic outbreaks and sequential dominance of dengue's four serotypes. Not only can this mechanism explain observed differences in serotype and disease distributions between neighbouring geographical areas, it also has important implications for inferring the nature and epidemiological consequences of immune mediated competition in multi-strain pathogen systems. PMID:24204241

Lourenco, Jose; Recker, Mario



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. PMID:22235184

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



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

NASA Astrophysics Data System (ADS)

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

Gkatzoflias, Dimitrios; Mellios, Giorgos; Samaras, Zissis



The influence of input device characteristics on spatial perception in desktop-based 3D applications  

Microsoft Academic Search

In desktop applications 3D input devices are mostly operated by the non-dominant hand to control 3D viewpoint navigation, while selection and geometry manipulations are handled by the dominant hand using the regular 2D mouse. This asymmetric bi-manual interface is an alternative to commonly used keyboard and mouse input, where the non-dominant hand assists the dominant hand with keystroke input to

Alexander Kulik; Jan Hochstrate; Andre Kunert; Bernd Froehlich



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

NASA Astrophysics Data System (ADS)

L'objectif de cette etude est d'elaborer un processus decisionnel a reference spatiale (PDRS) pour la mariculture. Le PDRS est applique aux eaux cotieres de la baie des Chaleurs, dans le golfe du Saint-Laurent (Canada). Une carte preliminaire regionale d'indices du potentiel maricole, d'une limite de resolution spatiale de 1 kmsp2, est produite avec des parametres du niveau 1. Ces parametres englobent la temperature de l'eau de surface, extraite des images AVHRR, la salinite, les courants ainsi que les pigments chlorophylliens, quantifies a l'aide de mesures in situ. Les images AVHRR, prises en 1994, ont ete utiliees comme reference primaire pour selectionner des aires pouvant supporter une activite maricole sur la cote nord de la baie des Chaleurs. La temperature de surface extraite de ces images permet une analyse mesoechelle a la fois qualitative et quantitative des processus cotiers observes pendant la periode d'acquisition des donnees. Les autres donnees, soit la salinite, les courants et les concentrations en pigments chlorophylliens, sont analysees de facon a identifier la variabilite spatio-temporelle des caracteristiques des eaux de surface. L'ensemble des informations permet de produire une carte preliminaire regionale d'indices du potentiel maricole de la partie centrale de la baie des Chaleurs. Selon cet indice (defini entre 0 et 1), le secteur de potentiel aquicole de 0,5 a 0,75 s'etend sur une superficie d'environ 300 kmsp2. La localisation de cette aire potentielle est en accord avec les fortes concentrations en pigments chlrophylliens, presentant des conditions environnementales ideales a une haute productivite biologique. Par la suite la carte preliminaire est modifiee en tenant compte des parametres du niveau 2. Ces parametres sont la geomorphologie littorale, la bathymetrie, les sediments en suspension, les vents, les vagues, le debit d'eau douce, la glace marine, le carbone organique dissous, les aires de peche et les sources de pollution. Ces parametres sont compares deux a deux par rapport a la carte preliminaire regionale d'indices du potentiel maricole pour determiner leur poids relatif. La carte finale produite avec ces parametres du niveau 2 presente un secteur ou les indices du potentiel maricole sont de 0,5 a 0,75. Ce secteur longe la cote et epouse les isobathes de 10 a 30 m de profondeur. L'effet de la profondeur d'eau semble avoir jouer un role important. Le secteur de potentiel maricole de 0,25 a 0,5 est toujours present et couvre une superficie d'environ 426 kmsp2. L'etude necessitera toujours un suivi des conditions environnementales prevalant dans la region. Ce suivi peut etre effectue a l'aide d'un outil de vision aerospatiale (capteurs de teledetection) et d'analyse spatio-temporelle (SIG-PDRS). (Abstract shortened by UMI.)

Habbane, Mohamed


Modeling the temporal, spatial and chemical variability in bioaccumulation: Issues and applications  

SciTech Connect

As new data are generated, it is becoming increasingly clear that there is considerable variability of chemical concentrations in aquatic organisms over time, space and chemical classes. Examples include the Bioaccumulation Factor (BAF) of PCB congeners in Green Bay and the Hudson estuary, PAHs in river systems, and mercury speciation over trophic space in lakes as well as chemical variability in organs of aquatic animals. Understanding the causes of such variability through food web transfer models is important in predicting the impacts of chemical accumulation on the aquatic and wildlife related ecosystems. Variability is considered from three sources: bioavailable water and sediment concentrations, ecosystem dynamics and chemical type and structure. BAF models are used to evaluate the contribution of these sources of variability to the observed BAF. For example: (1) for the Hudson estuary PCB congeners in the blue fish, a time variable BAF model indicates the significance of organism weight changes on uptake and deputation during migration into the estuary, (2) for methyl Hg in upper trophic levels, a BAF model indicates the potential for methylation by top predators, (3) for Green Bay PCB congeners, a BAF model as a function of log Kow does not explain observed variability within a Kow sub-class, and (4) for cadmium in fish, a pharmacokinetic model shows the significance of within-organism metal transfers. The current BAF models aid significantly in understanding the variability in organism chemical concentrations and also indicate gaps in predicting chemical-specific (e.g., PCB congener) behavior. Since toxicity effects and ecosystem health are ultimately determined by temporal and spatial exposure to specific chemicals, BAF models must be further developed to explain the variability in observed data.

Thomann, R.V. [Manhattan College, Riverdale, NY (United States). Dept. of Environmental Engineering



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

NASA Astrophysics Data System (ADS)

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

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



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

SciTech Connect

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

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



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: [Department of Environmental Engineering, Middle East Technical University, 06800 Ankara (Turkey)



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


Sensing and compensating of optical aberrations in closed-loop mode using a single spatial light modulator (SLM) for ophthalmic applications is demonstrated. Notwithstanding the disadvantages of the SLM, in certain cases, this multitasking capability of the device makes it advantageous over existing deformable mirrors (DMs), which are expensive and in general used for aberration compensation alone. A closed-loop adaptive optics (AO) system based on a single SLM was built. Beam resizing optics were used to utilize the large active area of the device and hence make it feasible to generate 137 active subapertures for wavefront sensing. While correcting Zernike aberrations up to fourth order introduced with the help of a DM (for testing purposes), diffraction-limited resolution was achieved. It is shown that matched filter and intensity-weighted centroiding techniques stand out among others. Closed-loop wavefront correction of aberrations in backscattered light from the eyes of three healthy human subjects was demonstrated after satisfactory results were obtained using an artificial eye, which was simulated with a short focal length lens and a sheet of white paper as diffuser. It is shown that the closed-loop AO system based on a single SLM is capable of diffraction-limited correction for ophthalmic applications. PMID:25253296

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




Microsoft Academic Search

Spatial regression models incorporating non-stationarity in the regression coefficients are popular. We propose a spatial variant of the Smooth Transition AutoRegressive (STAR) model that is more parsimonious than commonly used approaches and endogenously determines the extent of spatial parameter variation. Uncomplicated estimation and inference procedures are demonstrated using a neoclassical convergence model for United States counties.

Valerien O. Pede; Raymond J. G. M. Florax; Matthew T. Holt



An asymptotic wavefunction splitting procedure for propagating spatially extended wavefunctions: application to intense field photodissociation of H +2  

NASA Astrophysics Data System (ADS)

We describe an efficient procedure for propagation a spatially extended wavefunction evaluated on a small grid. The procedure involves the repeated splitting of the wavefunction into a part residing mainly in the interaction region (small fragment separation) and parts residing solely in the asymptotic region (large fragment separation), and propagation each part separately. The splitting is done by multiplying the wavefunction by the functions f( R) and 1- f( R), where R is the internuclear separation of an unbound degree of freedom and f(R) equals one in the interaction region and falls to zero in the asymptotic region. Each asymptotic piece of the wavefunction is propagated to some final time, in the momentum representation where it does not spread or translate, by a single application of a free-particle propagator. Unlike the use of an absorbing boundary, the total wavefunction can be reassembled at a later time by adding the individual asymptotic pieces, propagated to a common final time with a free-particle propagator, to the part of the wavefunction remaining in the interaction region. This procedure is well suited to propagation methods that evaluate the wavefunction on a spatial grid, because the amount of asymptotic region included in the grid, and thereforethe computational effort, can be minimized (the smaller the asymptotic region, the more frequent the splitting). The propagation method is demonstrated in the calculation of the fragment kinetic energy distribution produced by the intense field photodissociation of H +2. This example illustrates the propagation method for a system whose wavefunction becomes very extended with time due to multiphoton bound-continuum and continuum-continuum transitions.

Heather, Robert W.



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



Spatial mashup technology and real time data integration in geo-web application using open source GIS – a case study for disaster management  

Microsoft Academic Search

The Web 2.0 technologies and standards enable web as a platform by allowing the user participation in web application. In the realization of Web 2.0, new knowledge and services are created by combining information and services from different sources which are known as ‘mashups'. The present study focused on spatial mashup solution for disaster management using open source GIS, mobile

Harish Chandra Karnatak; Reedhi Shukla; Vinod Kumar Sharma; Y. V. S. Murthy; V. Bhanumurthy



A Single Application of MK801 Causes Symptoms of Acute Psychosis, Deficits in Spatial Memory, and Impairment of Synaptic Plasticity in Rats  

Microsoft Academic Search

Schizophrenia is mostly a progressive psychiatric illness. Although cognitive changes in chronic schizophrenia have been investi- gated, little is known about the consequences of a single psychotic epi- sode on memory mechanisms and formation. We investigated changes in hippocampal long-term potentiation (LTP) and spatial memory in a rat model of an acute psychotic episode. Application of NMDA receptor antagonists, such

Denise Manahan-Vaughan; Dorothea von Haebler; Christine Winter; Georg Juckel; Uwe Heinemann



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. PMID:23817443

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



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



Spatially Localized, One- and Two-Dimensional NMR Spectroscopy and in VivoApplication to Human Muscle  

NASA Astrophysics Data System (ADS)

The localized 1H MR spectrum of human muscle has recently been reported to feature unassigned, orientation-dependent resonance lines. For their characterization in vivo,various NMR techniques were combined with 3D spatial localization: 2D-J spectroscopy, zero-quantum- and Zeeman-order-filtering, double-quantum-filtering, 2D-constant-time COSY, dipolar-order filtering, and 2D-longitudinal-order separated spectroscopy. The successful implementation of these methods on a whole-body MR system and their application to study human subjects is described. 1H MR spectra of human muscle were found to feature residual dipolar couplings and anisotropic susceptibilities which render resonance frequencies, phases, and—with some sequences—signal intensities orientation dependent. Two of the unidentified resonances unequivocally form a dipolar doublet of two equivalent protons, centered at 3.93 ppm. All unknown as well as previously assigned peaks in the range between 2.7 and 3.6 ppm are either subject to dipolar coupling themselves or overlap with spectral contributions of metabolites involved in dipolar coupling. The methyl protons of creatine are likely to be subject to residual dipolar coupling and do therefore form a dipolar triplet and not a singlet as previously assumed. Finally, X3, a further unidentified peak at 3.5 ppm, appears to be part of a multiplet with its center at 3.3 ppm and overlapping the trimethylammonium resonance.

Kreis, Roland; Boesch, Chris


Small area estimation for semicontinuous skewed spatial data: an application to the grape wine production in Tuscany.  


Linear-mixed models are frequently used to obtain model-based estimators in small area estimation (SAE) problems. Such models, however, are not suitable when the target variable exhibits a point mass at zero, a highly skewed distribution of the nonzero values and a strong spatial structure. In this paper, a SAE approach for dealing with such variables is suggested. We propose a two-part random effects SAE model that includes a correlation structure on the area random effects that appears in the two parts and incorporates a bivariate smooth function of the geographical coordinates of units. To account for the skewness of the distribution of the positive values of the response variable, a Gamma model is adopted. To fit the model, to get small area estimates and to evaluate their precision, a hierarchical Bayesian approach is used. The study is motivated by a real SAE problem. We focus on estimation of the per-farm average grape wine production in Tuscany, at subregional level, using the Farm Structure Survey data. Results from this real data application and those obtained by a model-based simulation experiment show a satisfactory performance of the suggested SAE approach. PMID:24214421

Dreassi, Emanuela; Petrucci, Alessandra; Rocco, Emilia



A spatially-explicit approach for estimating carrying capacity: An application for the Atlantic menhaden ( Brevoortia tyrannus ) in Chesapeake Bay  

Microsoft Academic Search

A spatially-explicit methodology was developed for estimating system carrying capacities of fish stocks, and used to estimate\\u000a the seasonal and spatial patterns of carrying capacity of Chesapeake Bay for Atlantic menhaden (Brevoortia tyrannus). We used a spatially-explicit three-dimensional (3-D) model that divided the heterogeneous habitat of Chesapeake Bay into\\u000a over 4,000 cubes. Each cube represented a volume of water that

Jiangang Luo; Kyle J. Hartman; Stephen B. Brandt; Carl F. Cerco; Thomas H. Rippetoe



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

E-print Network

Correlation and heritability in neuroimaging datasets: A spatial decomposition approach) and dizygotic (DZ) twins. Conventionally, heritability is measured for univariate, scalar traits (e.g. IQ, body


Bayesian Factor Analysis for Spatially Correlated Data, With Application to Summarizing Area-Level Material Deprivation From Census Data  

Microsoft Academic Search

This article describes a Bayesian hierarchical model for factor analysis of spatially correlated multivariate data. The é rst level specié es, for each area on a map, the distribution of a vector of manifest variables conditional on an underlying latent factor; at the second level, the area- specié c latent factors have a joint distribution that incorporates spatial correlation. The

Hogan J. W; Rusty Tchernis



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

ERIC Educational Resources Information Center

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

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



XD(xanthene dyes)-DC-PVA (dichromated polyvinyl alcohol) for holographic recording: measurement of the spatial resolution and applications  

Microsoft Academic Search

We report on the characterization of some photopolymer recording materials based on DC-PVA films sensitized or non- sensitized by some xanthene dyes. The limit of the spatial resolution was determined for different sample preparation techniques. It is well known that the quality of the recorded hologram depends on the spatial resolution of the recording material. A bad resolution will reduce

Thierry Cornelissen; Christophe de Veuster; Jean J. Couture; Yvon L. Renotte; Yves F. Lion



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




Microsoft Academic Search

Until now, satellite data are only of limited use to Mid-European forest management. A major limitation is the low spatial reso lution of the commonly available satellite sensors. In this paper, we present a specific data fusion approach (local correlation model ling) which can be used to produce multispectral images with high spatial resolution based on panchromatic reference channels. Such

J. Hill; C. Diemer



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

E-print Network

We present the "condensation" method that exploits the heterogeneity of the probability distribution functions (PDF) of event locations to improve the spatial information content of seismic catalogs. As its name indicates, the condensation method reduces the size of seismic catalogs while improving the access to the spatial information content of seismic catalogs. Ranked by decreasing location errors, the PDFs of events are successively condensed onto better located and lower variance event PDFs. The obtained condensed catalog differs from the initial catalog by attributing different weights to each event, the set of weights providing an optimal spatial representation with respect to the spatially varying location capability of the seismic network. As a result of this condensation, which preserves the overall spatial probability density distribution, a large portion of the events (~25%) can be discarded without reducing the information content of the original catalog. Applied to Southern California seismicity...

Kamer, Y; Sornette, D; Woessner, J



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

NASA Astrophysics Data System (ADS)

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

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



The spatial Probit model-An application to the study of banking crises at the end of the 1990’s  

NASA Astrophysics Data System (ADS)

We use a spatial Probit model to study the effect of contagion between banking systems of different countries. Applied to the late 1990s banking crisis in Asia we show that the phenomena of contagion is better seized using a spatial than a traditional Probit model. Unlike the latter, the spatial Probit model allows one to consider the cascade of cross and feedback effects of contagion that result from the outbreak of one initial crisis in one country or system. These contagion effects may result either from business connections between institutions of different countries or from institutional similarities between banking systems.

Amaral, Andrea; Abreu, Margarida; Mendes, Victor



Application of a spatially referenced water quality model to predict E. coli flux in two Texas river basins  

E-print Network

Water quality models are applied to assess the various processes affecting the concentrations of contaminants in a watershed. SPAtially Referenced Regression On Watershed attributes (SPARROW) is a nonlinear regression based approach to predict...

, Deepti



Testing the importance of spatial configuration of winter habitat for woodland caribou: An application of graph theory  

E-print Network

T Conservation of remaining woodland caribou (Rangifer tarandus caribou) populations requires land management. Ã? 2006 Elsevier Ltd. All rights reserved. 1. Introduction Woodland caribou (Rangifer tarandusTesting the importance of spatial configuration of winter habitat for woodland caribou

Fortin, Marie Josee


Detection of multimode spatial correlation in PDC and application to the absolute calibration of a CCD camera  

E-print Network

We propose and demonstrate experimentally a new method based on the spatial entanglement for the absolute calibration of analog detector. The idea consists on measuring the sub-shot-noise intensity correlation between two branches of parametric down conversion, containing many pairwise correlated spatial modes. We calibrate a scientific CCD camera and a preliminary evaluation of the statistical uncertainty indicates the metrological interest of the method.

Giorgio Brida; Ivo Pietro Degiovanni; Marco Genovese; Maria Luisa Rastello; Ivano Ruo-Berchera



A multilevel model for spatially correlated binary data in the presence of misclassification: an application in oral health research.  


Dental caries is a highly prevalent disease affecting the tooth's hard tissues by acid-forming bacteria. The past and present caries status of a tooth is characterized by a response called caries experience (CE). Several epidemiological studies have explored risk factors for CE. However, the detection of CE is prone to misclassification because some cases are neither clearly carious nor noncarious, and this needs to be incorporated into the epidemiological models for CE data. From a dentist's point of view, it is most appealing to analyze CE on the tooth's surface, implying that the multilevel structure of the data (surface-tooth-mouth) needs to be taken into account. In addition, CE data are spatially referenced, that is, an active lesion on one surface may impact the decay process of the neighboring surfaces, and that might also influence the process of scoring CE. In this paper, we investigate two hypotheses: that is, (i) CE outcomes recorded at surface level are spatially associated; and (ii) the dental examiners exhibit some spatial behavior while scoring CE at surface level, by using a spatially referenced multilevel autologistic model, corrected for misclassification. These hypotheses were tested on the well-known Signal Tandmobiel® study on dental caries, and simulation studies were conducted to assess the effect of misclassification and strength of spatial dependence on the autologistic model parameters. Our results indicate a substantial spatial dependency in the examiners' scoring behavior and also in the prevalence of CE at surface level. PMID:23996301

Mutsvari, Timothy; Bandyopadhyay, Dipankar; Declerck, Dominique; Lesaffre, Emmanuel



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.



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

NASA Astrophysics Data System (ADS)

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

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



P-124: Study of Stacked Alignment Layers on a Single Substrate with Spatial Liquid Crystal Pretilt Angles and its Applications  

E-print Network

= is a position vector in the simulation cell and the liquid crystal director field is denoted by )sinP-124: Study of Stacked Alignment Layers on a Single Substrate with Spatial Liquid Crystal Pretilt for Display Research, Department of Electrical and Electronic Engineering Hong Kong University of Science


The development of a light-collecting probe with high spatial resolution applicable to randomly fluctuating combustion fields  

NASA Astrophysics Data System (ADS)

A high-luminosity-light-collection system for highly spatial detection of chemiluminescence of radical species in flames has been developed. The system, multi-colour integrated Cassegrain receiving optics (MICRO) is based upon a Cassegrain-type configuration, which implies that it employs only reflective components (in combination with an optical fibre for light collection). It provides therefore spherical- and chromatic-aberration-free detection, which is of importance for high-spatial-resolution measurements and for the simultaneous monitoring of signals in different wavelength regions from a given spatial volume. The effective light-collection volume has been estimated to be only 1.6 mm × 0.2 mm × 0.2 mm by ray-tracing techniques, which is more than three orders of magnitude smaller than that provided by a corresponding simple single-lens system and comparable to that of laser-based techniques, e.g. Doppler anemometry. The system is also easily aligned since the active probe volume can be visualized by sending in visible light through the system in the reverse direction. In order to demonstrate the performance of the system, OH-radical chemiluminescence in a Bunsen flame was monitored using MICRO and compared with the ion-current signal from a Langmuir probe with a minute sensor tip. A good correlation between the fluctuations in the two signals could be obtained, proving the high spatial and temporal resolution of the MICRO system.

Akamatsu, Fumiteru; Wakabayashi, Takashi; Tsushima, Shohji; Katsuki, Masashi; Mizutani, Yukio; Ikeda, Yuji; Kawahara, Nobuyuki; Nakajima, Tsuyoshi



On measuring the fractal anisotropy of 2-D geometrical sets: Application to the spatial distribution of fractures  

Microsoft Academic Search

This work addresses a methodology on how to estimate and correlate the fractal anisotropy of a 2-D spatial distribution of segments with structural geometrical parameters and the relative dating of fracture sets. Tectonic characterisation of fracture traces can be performed to classify fractures into families, according to the tectonic event. To analyse their fractal anisotropy, several Cantorian profiles were constructed

R. Pérez-López; C. Paredes



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

Microsoft Academic Search

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.

De Sapio



Study of a high spatial resolution 10B-based thermal neutron detector for application in neutron reflectometry: the Multi-Blade prototype  

NASA Astrophysics Data System (ADS)

Although for large area detectors it is crucial to find an alternative to detect thermal neutrons because of the 3He shortage, this is not the case for small area detectors. Neutron scattering science is still growing its instruments' power and the neutron flux a detector must tolerate is increasing. For small area detectors the main effort is to expand the detectors' performances. At Institut Laue-Langevin (ILL) we developed the Multi-Blade detector which wants to increase the spatial resolution of 3He-based detectors for high flux applications. We developed a high spatial resolution prototype suitable for neutron reflectometry instruments. It exploits solid 10B-films employed in a proportional gas chamber. Two prototypes have been constructed at ILL and the results obtained on our monochromatic test beam line are presented here.

Piscitelli, F.; Buffet, J. C.; Clergeau, J. F.; Cuccaro, S.; Guérard, B.; Khaplanov, A.; La Manna, Q.; Rigal, J. M.; Van Esch, P.



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.



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.



Spatial Databases - Accomplishments and Research Needs  

Microsoft Academic Search

Spatial databases, addressing the growing data management and analysis needs of spatial applications such as geographic information systems, have been an active area of research for more than two decades. This research has produced a taxonomy of models for space, spatial data types and operators, spatial query languages and processing strategies, as well as spatial indexes and clustering techniques. However,

Shashi Shekhar; Sanjay Chawla; Sivakumar Ravada; Andrew Fetterer; Xuan Liu; Chang-tien Lu



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

NASA Technical Reports Server (NTRS)

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

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



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

NASA Technical Reports Server (NTRS)

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

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



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

Microsoft Academic Search

Monitoring the environment of fish is a key component of the ecosystem approach to fisheries management. Here, we propose a methodology to statistically monitor time series of maps of environmental indices. These maps were derived from a 37-year hindcast of a coupled physical–biogeochemical model. The space–time variability in the maps was decomposed using empirical orthogonal functions into time-invariant spatial patterns

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



Assessment of parameter settings for SPM5 spatial normalization of structural MRI data: Application to type 2 diabetes  

Microsoft Academic Search

Spatial normalization is the process of standardizing images of different subjects into the same anatomical space. The goal of this work was to assess standard and unified methods in SPM5 for the normalization of structural magnetic resonance imaging (MRI) data acquired in mid-life\\/elderly subjects with diabetes. In this work, we examined the impact of different parameters (i.e. nonlinear frequency cutoff,

Bedda L. Rosario; Scott K. Ziolko; Lisa A. Weissfeld; Julie C. Price



A web-based, component-oriented application for spatial modelling of habitat suitability of mosquito vectors  

Microsoft Academic Search

This paper proposes a web-enabled computational environment for the spatial modelling of habitat suitability of mosquito vectors. Under a component-based architecture and implemented using an object-oriented data model, we integrate database interfaces, Web feature services (WFS) based on the open GIS consortium (OGC) protocols, and the data-mining tool WEKA, coupled through Java servlet scripts (JSP). The prototype, based exclusively on

P. Zeilhofer; P. S. Arraes Neto; W. Y. Maja; D. A. Vecchiato



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



Spatial application of BROOK90 in managed Inner Mongolia grasslands: a case study on evapotranspiration from 2002 to 2011  

NASA Astrophysics Data System (ADS)

Water balance losses in semi-arid grasslands are determined by evapotranspiration (ET). Although previous studies demonstrated point measurements of ET in Inner Mongolia grasslands are valuable at the field scale, little is known about the spatial distribution of ET in this area, where precipitation and ET have a high spatial variability. We present a simple method for modelling spatial ET at 1 km and 8-day resolution with the hydrological model BROOK90 and MODIS data for the 2,600 sqkm of typical steppe in the Xilin river catchment and the model results for the main vegetation periods (23 April to 28 August) of the last 10 years. BROOK90 is a physically-based, process-orientated hydrological model, that separates the productive transpiration (T) and the non-productive evaporation (E) based on the Shuttleworth and Wallace modification of the Penman-Monteith equation. BROOK90 was parameterised from eddy covariance data. After model parameterisation no additional ground-based data are needed for this method, because the daily model input data (precipitation, minimum and maximum air temperature) were derived from manipulation of MODIS leaf area index and land surface temperature data products. The spatial mean ET during the 10 years of the study period was 156 mm with a standard deviation of 22 mm and a coefficient of variation of 28%. Lowest mean ET was 119 mm in 2009 and highest mean ET was 197 mm in 2003. However, for individual pixels, ET varied from 67 mm to 319 mm. Maximum ET in this area varied between 3 mm d-1 and 5 mm d-1 during 8-day intervals. The analysis of spatial and temporal patterns of E and T demonstrates, our method could be a useful tool towards a better understanding of evapotranspiration in managed grassland of Inner Mongolia, and may help to adjust unsustainable land management practices towards a better adapted livestock management. ET in 2006: Probability density functions and summary statistics (first, second and third quartile) of the components of ET from 25 May to 28 August. Evaporation is depicted on the left side in light grey and transpiration is shown on the right side in dark grey. The + shows ET as the sum of its three components and the triangle shows ET without E from interception.

Schaffrath, D.; Bernhofer, C.



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

USGS Publications Warehouse

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

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



Spatial variability of near surface soil moisture in an alpine catchment: application of a wireless network of meteorological stations  

NASA Astrophysics Data System (ADS)

Soil moisture is an essential control on hydrological and meteorological behavior and knowledge of its spatial variability is considered to be of high importance for the performance of distributed hydrological models. Near surface soil moisture measurements can be provided by remote sensing on large scales or by point measurements on local scales. For the study of small and medium scale catchments in complex terrain, it is necessary to know the soil moisture on intermediate scales in order to link it with evapotranspiration and runoff processes. Moreover, the time resolution of the soil moisture measurements is often a limiting factor to correctly assess the impact of the soil moisture spatial variability on hydrological models. Few studies have tried to assess the spatial variability of soil moisture in mountainous catchment. Since 2008, an alpine watershed in the Swiss Alps has been intensely monitored with a network of wireless meteorological stations. The study area covers a total surface of 20.4 km2 with altitude ranges from 1775 m at the outlet to 3206 m above sea level (mean elevation: 2422.8m) and is characterized by steep (mean slope: 31.6°, maximum 88.9°) and variable terrain. Among other meteorological forcing parameters, soil moisture is measured using Decagon 5TM and 5TE probes at typical depths of 20cm and 40cm below surface with a time resolution of one minute. We present some preliminary results from statistical and geostatistical analysis of the soil moisture dataset. Moreover, we investigate the information content that antecedent soil moisture measurements add to rainfall measurements in order to predict and understand both runoff events and recession flows.

Mutzner, R.; Weijs, S. V.; Barrenetxea, G.; Parlange, M. B.



Epidemiologic analyses of spatial clustering of bovine ephemeral fever outbreaks. I. Application of the negative binomial distribution.  


An epidemic that propagates through a population results in a contagious spatial pattern. The incidence per farm of bovine ephemeral fever (BEF) outbreaks in the 22 areas of Fukuoka Prefecture in 1988 was well explained by the negative binomial distribution, which is generally considered, as the clustering of the outbreaks. Furthermore, the clustering was analyzed with three categories of vaccination rate (No. 1-40%, and 40-80%). As a result, the no vaccination and high vaccination rate (41-80%) groups tended to shift to similarly the Poisson distribution. It may be speculated that an insufficient vaccination control of the BEF was influenced with the clustering. PMID:8461418

Ogawa, T; Ishibashi, K; Imamura, K; Kurashige, S; Hatakeyama, H



Application of finite-element methods to dynamic analysis of flexible spatial and co-planar linkage systems, part 2  

NASA Technical Reports Server (NTRS)

An approach is described to modeling the flexibility effects in spatial mechanisms and manipulator systems. The method is based on finite element representations of the individual links in the system. However, it should be noted that conventional finite element methods and software packages will not handle the highly nonlinear dynamic behavior of these systems which results form their changing geometry. In order to design high-performance lightweight systems and their control systems, good models of their dynamic behavior which include the effects of flexibility are required.

Dubowsky, Steven



A Comparison of the Spatial Linear Model to Nearest Neighbor (k-NN) Methods for Forestry Applications  

PubMed Central

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



High-Field fMRI for Human Applications: An Overview of Spatial Resolution and Signal Specificity  

PubMed Central

In the last decade, dozens of 7 Tesla scanners have been purchased or installed around the world, while 3 Tesla systems have become a standard. This increased interest in higher field strengths is driven by a demonstrated advantage of high fields for available signal-to-noise ratio (SNR) in the magnetic resonance signal. Functional imaging studies have additional advantages of increases in both the contrast and the spatial specificity of the susceptibility based BOLD signal. One use of this resultant increase in the contrast to noise ratio (CNR) for functional MRI studies at high field is increased image resolution. However, there are many factors to consider in predicting exactly what kind of resolution gains might be made at high fields, and what the opportunity costs might be. The first part of this article discusses both hardware and image quality considerations for higher resolution functional imaging. The second part draws distinctions between image resolution, spatial specificity, and functional specificity of the fMRI signals that can be acquired at high fields, suggesting practical limitations for attainable resolutions of fMRI experiments at a given field, given the current state of the art in imaging techniques. Finally, practical resolution limitations and pulse sequence options for studies in human subjects are considered. PMID:22216080

Olman, Cheryl A; Yacoub, Essa



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

NASA Technical Reports Server (NTRS)

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Technical Reports Server (NTRS)

This report presents three-year accomplishments from the national program on Commercial Remote Sensing and Geospatial Technology (CRSGT) application to transportation, administered by the U.S. Department of Transportation (U.S. DOT) in collaboration with the National Aeronautics and Space Administration (NASA). The joint program was authorized under Section 5113 of the Transportation Equity Act for the 21st Century (TEA-21). This is the first national program of its type focusing on transportation applications of emerging commercial remote sensing technologies. U.S. DOT's Research and Special Programs Administration manages the program in coordination with NASA's Earth Science Enterprise's application programs. The program focuses on applications of CRSGT products and systems for providing smarter and more efficient transportation operations and services. The program is performed in partnership with four major National Consortia for Remote Sensing in Transportation (NCRST). Each consortium focuses on research and development of products in one of the four priority areas for transportation application, and includes technical application and demonstration projects carried out in partnership with industries and service providers in their respective areas. The report identifies products and accomplishments from each of the four consortia in meeting the goal of providing smarter and more efficient transportation services. The products and results emerging from the program are being implemented in transportation operations and services through state and local agencies. The Environmental Assessment and Application Consortium (NCRST-E) provides leadership for developing and deploying cost effective environmental and transportation planning services, and integrates CRSGT advances for achieving smarter and cost effective corridor planning. The Infrastructure Management Consortium (NCRST-I) provides leadership in technologies that achieve smarter and cheaper ways of managing transportation infrastructure assets, operation, and inspection, and integrates CRSGT advances for achieving infrastructure security. The Traffic Flow Consortium (NCRST-F) provides leadership to develop new tools for regional traffic flow management including heavy vehicles and intermodal flow of freight, and integrates CRSGT advances for complementing and extending the reach of ITS user services. The Safety, Hazards and Disasters (NCRST-H) provides leadership for deploying remote sensing technology to locate transportation hazards and improve disaster recovery, and integrates CRSGT advances for application to protect transportation systems from terrorism. The DOT-NASA team is proud to present this report of accomplishments on products and results emerging from the joint program for application to transportation practice.



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


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



Application of multi-scale variography for inferring the spatial variability of the hydraulic conductivity of a sandy aquifer  

NASA Astrophysics Data System (ADS)

In the framework of the disposal of short-lived low- and intermediate-level radioactive waste in a near-surface disposal facility in Dessel (Belgium), extensive characterization of the hydraulic conductivity (K) in the shallow Neogene aquifer has been performed at a regional scale. In the last few years the small-scale heterogeneity has been additionally characterized by outcrop analogue, hydraulic direct push, and borehole core air permeameter studies. The gathered data now include a) more than 350 hydraulic conductivity measurements on samples from 8 cored boreholes, mostly reaching depths of ~50 m and data at 2 m intervals, b) more than 5000 air permeability measurements on the same borehole cores, c) more than 250 cone penetration tests (CPTs) with depths down to 40 m and data at 2 cm intervals, d) over 100 dissipation tests performed during the CPT campaigns, e) 17 direct push injections loggings, 6 hydraulic profiling tool logs, and 6 direct push slug tests, f) several hundreds of air permeability measurements on outcrop analogues of the aquifer sediments, and g) numerous grain size analyses. The current study aims to quantify the heterogeneity of K from the centimetre- to the kilometre-scale and to check the compatibility of the spatial variability revealed by the different datasets. This is achieved through gathering all K values (either direct measurements, calibrated relative K values, or K estimates from secondary data), and the use of variography to quantify spatial variability in terms of two-points geostatistics. The results are discussed, and the main differences between the different data sources are explained. In a final step, different multi-scale variogram models are proposed for capturing the main characteristics of multi-scale variability within the shallow Neogene aquifer in Belgium.

Rogiers, Bart; Vienken, Thomas; Gedeon, Matej; Batelaan, Okke; Mallants, Dirk; Huysmans, Marijke; Dassargues, Alain



Spatial Displays and Spatial Instruments  

NASA Technical Reports Server (NTRS)

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

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




E-print Network

METRICS IN AUTOMOTIVE APPLICATIONS Christian Lottermann1,2 Alexander Machado1 Damien Schroeder2 Wolfgang Hintermaier1 Eckehard Steinbach2 1 BMW Group, Munich, Germany {} 2 Institute for Media the video. Besides the influence of the content-dependent parameters of the source video and the encoding

Steinbach, Eckehard


Combining conservation value, vulnerability, and effectiveness of mitigation actions in spatial conservation decisions: an application to coastal oil spill combating.  


Increasing oil transportation and severe oil accidents in the past have led to the development of various sensitivity maps in different countries all over the world. Often, however, the areas presented on the maps are far too large to be safeguarded with the available oil combating equipment and prioritization is required to decide which areas must be safeguarded. While oil booms can be applied to safeguard populations from a drifting oil slick, decision making on the spatial allocation of oil combating capacity is extremely difficult due to the lack of time, resources and knowledge. Since the operational decision makers usually are not ecologists, a useful decision support tool including ecological knowledge must be readily comprehensible and easy to use. We present an index-based method that can be used to make decisions concerning which populations of natural organisms should primarily be safeguarded from a floating oil slick with oil booms. The indices take into account the relative exposure, mortality and recovery potential of populations, the conservation value of species and populations, and the effectiveness of oil booms to safeguard different species. The method has been implemented in a mapping software that can be used in the Gulf of Finland (Baltic Sea) for operational oil combating. It could also be utilized in other similar conservation decisions where species with varying vulnerability, conservational value, and benefits received from the management actions need to be prioritized. PMID:21437741

Ihaksi, Taina; Kokkonen, Teemu; Helle, Inari; Jolma, Ari; Lecklin, Tiina; Kuikka, Sakari



Focusing integrated mirrors realized by silver ion-exchange: application to laser Doppler velocimeter with ultrahigh spatial resolution  

NASA Astrophysics Data System (ADS)

Integrated reflecting mirrors based on total internal reflection are first proposed in this paper. They are design to be fabricated by ion-exchange process on a glass substrate. Theoretical modelling of parabolic and elliptic mirrors is presented. Surface and buried elliptic mirrors are fabricated at the same time as the rest of the guiding structure by a silver ion-exchange followed by a field assisted potassium exchange in the second case. Light coming out of a singlemode waveguide is focused outside the integrated component at distances of 500 ?m. Light beam width of 13 ?m at 1/e2 of the maximum intensity were measured. Second, those mirrors are used to design an integrated laser Doppler velocimeter with ultra-high spatial resolution. Interference pattern of 22 x 33 x 10 ?m3 with fringe spacing of 0.8 ?m was produced at the focal point of the integrated mirrors in air. The fringe visibility measured in the center of the measuring volume is 1.

Lemaitre-Auger, Pierre; Gluck, Stephane; Bucci, Davide; Cartellier, Alain; Benech, Pierre



High Spatial resolution GaN and Optical Photon Counting Detectors with sub-nanosecond timing for Astronomical and Space Sensing Applications  

NASA Astrophysics Data System (ADS)

Recent advances in UV-Visible ground and space borne detectors with the unique ability to record photon X,Y,T high fidelity information include the development of GaN UV photocathodes and cross strip high resolution position encoding readouts. Such sensors have the distinct advantage of being able to record the accurate time of each detected photon event, which is important for time dependent applications in space astronomy, biology, and time of flight instruments. Newly developed GaN photocathodes have achieved up to 80% quantum efficiency at 120 nm and in the opaque mode they demonstrate high efficiency up to a cutoff wavelength of about 360 nm. Meanwhile semitransparent GaN cathodes have achieved ~20% quantum efficiency in the 240 nm to 360 nm regime. Imaging devices with these photocathodes have demonstrated good spatial resolution and uniformity, with relatively low background event rates. For photon counting imaging detectors we have developed cross strip anode readouts with large, high spatial resolution formats capable of high counting rates and extended lifetimes. We have achieved resolutions of < 10 !m in tests over 32 mm x 32 mm anodes with excellent linearity. High-speed electronics for the cross strip readout are currently under development and should achieve > 1 MHz for random photon rates, and we have demonstrated time tagging of events to better than 1ns. A variety of sealed tube detectors are also in development with both GaN and GaAs photocathodes.

Siegmund, O.; Vallerga, J.; Welsh, B.; Tremsin, A.; McPhate, J.


An Application of Induced Seismicity Data Analysis for Detection of Spatial Structures and Temporal Regimes of Deformation Processes in Hydrocarbon Fields  

NASA Astrophysics Data System (ADS)

- An application of induced seismicity data to detection of deformation processes is considered. Methodology of the data interpretation is based on the conception of rock mass as a block medium adopting energy from internal and external sources and forming dissipative structures. The ideas from the stability theory of nonlinear systems are used. A spatial and temporal distribution of seismicity is analyzed to discover a regular, predictable component of seismic regime. Various methods were used for the analysis of seismic events listed in the seismic catalog in the region of Romashkino oil-field (Russia). Quasi-harmonious oscillations of seismic activity were found. They were synchronized in time with change of injection effectiveness. Spatial structures of seismicity were detected, and it was shown that these structures are in good agreement with tectonic faults. Data analysis shows correlation between seismic activity and imbalance of injected and extracted fluids. The obtained results show that water-injection effectiveness decreases during periods of increased seismic activity and increases during periods of low seismic activity.

Turuntaev, S. B.; Razumnaya, O. A.


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

NASA Astrophysics Data System (ADS)

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

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



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



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 adversely influenced by the underlying land cover. 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 extending 0.1 km downwind of two hydrocarbon storage tanks at the Inglewood Oil Field in Los Angeles, California (USA) 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 extended more than 1 km downwind of known seep locations. 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.



Effect of spatial confinement on magnetic hyperthermia via dipolar interactions in Fe?O? nanoparticles for biomedical applications.  


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

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



Nova Spatial  

NSDL National Science Digital Library

Nova Spatial is a software firm which has developed GIS software for the Android (TM) mobile device platform. Products include pcMapper Lite and extensions that allow for creation of GIS shape files using just a standard smartphone.

Llc, Nova S.


Optical Array Processor: Laboratory Results  

NASA Astrophysics Data System (ADS)

A Space Integrating (SI) Optical Linear Algebra Processor (OLAP) is described and laboratory results on its performance in several practical engineering problems are presented. The applications include its use in the solution of a nonlinear matrix equation for optimal control and a parabolic Partial Differential Equation (PDE), the transient diffusion equation with two spatial variables. Frequency-multiplexed, analog and high accuracy non-base-two data encoding are used and discussed. A multi-processor OLAP architecture is described and partitioning and data flow issues are addressed.

Casasent, David; Jackson, James; Vaerewyck, Gerard



Fluid-structure interaction applied to the analysis of a test sandwich panel typical for spatial applications  

NASA Astrophysics Data System (ADS)

A study to demonstrate the feasibility of an original method dedicated to fluid/structure interaction phenomena is presented. Based on the fact that the interaction is moderate, the proposed method consists of a time domain calculation coupling two independent kernels, a structural and an acoustical one, in an iterative scheme. The developed code, named ASTRYD-C, was applied to the response analysis of a test sandwich panel in air. Comparisons between numerical and experimental results for various configurations of this light structure, typical of space applications, show good agreement and demonstrate the ability of the proposed method to solve problems where coupling phenomena are significant.

Vaucherdelacroix, D.; Perret, L.; Parot, J. M.



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


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



Recurrence Plots for Spatial Data  

E-print Network

Recurrence Plots for Spatial Data Norbert Marwan, Peter Saparin, Jürgen Kurths Nonlinear Dynamics Group #12;Outline · Introduction · Recurrence plots & quantification · Spatial extension · Application #12;Recurrence Plots #12;Recurrence Plots · visualisation of phase space (Eckmann et al, 1987) Ri

Seehafer, Norbert


Applications of a spatial extension to CIELAB X-M. Zhanga, J.E. Farrell, b, and B.A. Wandella  

E-print Network

according to the spatial sensitivity of the human eye for that color component. Third, the ltered images of multi-level halftone images. Our com- putations were based on a spatial color di erence metric, S color patches. S-CIELAB includes a pre-processing stage that accounts for certain aspects of the spatial

Wandell, Brian A.


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

USGS Publications Warehouse

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

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



Spatial Mass  

E-print Network

In analogy to the transverse mass constructed from two objects, we define the spatial mass constructed from the input objects 3-vector momenta. This observable is insensitive to jet mass scale and resolution uncertainties when constructed from small-radius hadronic jets. Thus it improves the effective resolution on multijet masses for searches and measurements in hadronic final states. To illustrate the efficacy of the spatial mass, we consider a top quark mass measurement at the Large Hadron Collider (LHC) in the 3-jet final state. The reduction in uncertainty comes with a negligible cost in sensitivity.

Nachman, Benjamin



Spatial Mass  

E-print Network

In analogy to the transverse mass constructed from two objects, we define the spatial mass constructed from the input objects 3-vector momenta. This observable is insensitive to jet mass scale and resolution uncertainties when constructed from small-radius hadronic jets. Thus it improves the effective resolution on multijet masses for searches and measurements in hadronic final states. To illustrate the efficacy of the spatial mass, we consider a top quark mass measurement at the Large Hadron Collider (LHC) in the 3-jet final state. The reduction in uncertainty comes with a negligible cost in sensitivity.

Benjamin Nachman; Ariel Schwartzman



Planetary Spatial Analyst  

NASA Technical Reports Server (NTRS)

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

Keely, Leslie



Spatial networks  

NASA Astrophysics Data System (ADS)

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

Barthélemy, Marc



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



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.



Intraspecific application of the mid-domain effect model: spatial and temporal nest distributions of green turtles, Chelonia mydas, at Tortuguero, Costa Rica  

Microsoft Academic Search

The mid-domain effect (MDE) model was developed to evaluate patterns of species richness. We applied the MDE model to intraspecific distribution patterns - the spatial and temporal nest distributions of green turtles, Chelonia mydas, at Tortuguero, Costa Rica, from 1972 to 2000. Spatial and temporal distributions of green turtle nests at Tortuguero did not exhibit significant annual variation over this

Manjula Tiwari; Karen A. Bjorndal; Alan B. Bolten; Benjamin M. Bolker



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



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.



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



Visualizations in Spatial Algorithm Development  

NASA Astrophysics Data System (ADS)

Spatial algorithms as used in Geographic Information Systems (GIS) can be difficult to understand and use, both for the developers and users. Knowledge transfer between developers and GIS enabled application users is often inadequate, incomprehensible or non-existent. Novel approaches for spatially indexing and searching data involve trade-offs; all have their limitations and advantages. Effectively communicating these trade-offs is a challenge. Both the limitations and strong points of any algorithms used in scientific applications must be explained to end-users in an easily understood and digestible manner. Written documentation is only one way of describing an algorithm. Images, animations, and interactive demos have long been used to aid in understanding spatial algorithms but their adoption and use could be increased. This session demonstrates how to include interactive visualizations from a project's inception and outlines the possibility of using these visualizations not only as eventual documentation, but also as verification criteria for spatial algorithm development. Interactive tools, such as Google Earth, can be used to create and visualize inputs to spatial algorithms and validate results. During development, a developer can benefit from constant feedback and the ability to quickly test changes and new code. This session will also demonstrate methods of documenting spatial algorithms for end users. The use of literate programming tools such as docco, http://, and spatial visualizations document the code and aid in producing documentation for scientists and developers.

Gilman, J.; Pilone, D.; Mitchell, A. E.; Baynes, K.



Stability of active systems with a spatially periodic activity: Analysis of a simple model and application to the boiling crisis problem.  


We investigate theoretically the possibility to control the transition between two metastable states in reactive systems by imposing a spatial modulation. In particular, we consider the technologically very important case of the transition between the low temperature (nucleate boiling) and the high temperature (film boiling) phases of boiling of a liquid over a heat generating element, also known as the boiling crisis. With the help of a simplified model, we demonstrate that the dangerous regime where the high temperature phase invades the whole system requires a larger heat power in a periodically spatially modulated system, than in a uniform system. The possibility that a local perturbation, such as a small gas bubble, may induce locally a transition to the film boiling state is also considered. We show that the transition to the film boiling regime is hindered in a spatially periodic system. (c) 2002 American Institute of Physics. PMID:12779590

Pumir, Alain; Barelko, Viktor V.



Theoretical prediction of the source-detector separation distance suited to the application of the spatially resolved spectroscopy from the near-infrared attenuation data cube of tissues  

E-print Network

The modified Beer-Lambert law (MBL) and the spatially resolved spectroscopy are used to measure the tissue oxidation in muscles and brains by the continuous wave near-infrared spectroscopy. The spatially resolved spectroscopy predicts the change in the concentration of the absorber by measuring the slope of attenuation data according to the separation and calculating the absorption coefficients of tissue on the basis of the slop in attenuation at the separation distance satisfying the linearity of this slop. This study analyzed the appropriate source-detector separation distance by using the diffuse approximation resolution for photon migration when predicting the absorption coefficient by the spatially resolved spectroscopy on the basis of the reflective image of the tissue. We imagine the 3 dimensional attenuation image with the absorption coefficient, reduced scattering coefficient and separation distance as its axes and obtained the attenuation data cube by calculating the attenuation on a certain interva...

Ri, Yong-Wu; Im, Song-Jin



SMART: a spatially explicit bio-economic model for assessing and managing demersal fisheries, with an application to italian trawlers in the strait of sicily.  


Management of catches, effort and exploitation pattern are considered the most effective measures to control fishing mortality and ultimately ensure productivity and sustainability of fisheries. Despite the growing concerns about the spatial dimension of fisheries, the distribution of resources and fishing effort in space is seldom considered in assessment and management processes. Here we propose SMART (Spatial MAnagement of demersal Resources for Trawl fisheries), a tool for assessing bio-economic feedback in different management scenarios. SMART combines information from different tasks gathered within the European Data Collection Framework on fisheries and is composed of: 1) spatial models of fishing effort, environmental characteristics and distribution of demersal resources; 2) an Artificial Neural Network which captures the relationships among these aspects in a spatially explicit way and uses them to predict resources abundances; 3) a deterministic module which analyzes the size structure of catches and the associated revenues, according to different spatially-based management scenarios. SMART is applied to demersal fishery in the Strait of Sicily, one of the most productive fisheries of the Mediterranean Sea. Three of the main target species are used as proxies for the whole range exploited by trawlers. After training, SMART is used to evaluate different management scenarios, including spatial closures, using a simulation approach that mimics the recent exploitation patterns. Results evidence good model performance, with a noteworthy coherence and reliability of outputs for the different components. Among others, the main finding is that a partial improvement in resource conditions can be achieved by means of nursery closures, even if the overall fishing effort in the area remains stable. Accordingly, a series of strategically designed areas of trawling closures could significantly improve the resource conditions of demersal fisheries in the Strait of Sicily, also supporting sustainable economic returns for fishermen if not applied simultaneously for different species. PMID:24465971

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



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

PubMed Central

Management of catches, effort and exploitation pattern are considered the most effective measures to control fishing mortality and ultimately ensure productivity and sustainability of fisheries. Despite the growing concerns about the spatial dimension of fisheries, the distribution of resources and fishing effort in space is seldom considered in assessment and management processes. Here we propose SMART (Spatial MAnagement of demersal Resources for Trawl fisheries), a tool for assessing bio-economic feedback in different management scenarios. SMART combines information from different tasks gathered within the European Data Collection Framework on fisheries and is composed of: 1) spatial models of fishing effort, environmental characteristics and distribution of demersal resources; 2) an Artificial Neural Network which captures the relationships among these aspects in a spatially explicit way and uses them to predict resources abundances; 3) a deterministic module which analyzes the size structure of catches and the associated revenues, according to different spatially-based management scenarios. SMART is applied to demersal fishery in the Strait of Sicily, one of the most productive fisheries of the Mediterranean Sea. Three of the main target species are used as proxies for the whole range exploited by trawlers. After training, SMART is used to evaluate different management scenarios, including spatial closures, using a simulation approach that mimics the recent exploitation patterns. Results evidence good model performance, with a noteworthy coherence and reliability of outputs for the different components. Among others, the main finding is that a partial improvement in resource conditions can be achieved by means of nursery closures, even if the overall fishing effort in the area remains stable. Accordingly, a series of strategically designed areas of trawling closures could significantly improve the resource conditions of demersal fisheries in the Strait of Sicily, also supporting sustainable economic returns for fishermen if not applied simultaneously for different species. PMID:24465971

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



Application of optical emission spectroscopy for He I considering the spatial structure of radiation trapping in MAP-II divertor simulatora)  

NASA Astrophysics Data System (ADS)

The He I optical emission spectroscopy that considers the spatial structure of radiation trapping was proposed by us and was applied to a MAP-II divertor simulator. The spatial distribution of the optical escape factor was calculated from the n P1 (n ?3) state profiles measured by visible spectroscopy. The profile of 2 P1, which is immeasurable by visible spectroscopy, needs to be broader than that of the 3 P1 state. The sensitivity of the 2 P1 profile to the Te value estimated by He I spectroscopy is investigated.

Iida, Y.; Kado, S.; Muraki, A.; Tanaka, S.



Semantic Caching for Multiresolution Spatial Query Processing in Mobile Environments  

Microsoft Academic Search

Spatial data are particularly useful in mobile environments. However, due to the low bandwidth of most wireless networks, developing large spatial database applications becomes a challenging process. In this paper, we provide the flrst attempt to combine two important techniques, multiresolution spatial data structure and semantic caching, towards ef- flcient spatial query processing in mobile environments. Based on the study

Sai Sun; Xiaofang Zhou; Heng Tao Shen



Applications of a spatial extension to CIELAB XM. Zhang a , J.E. Farrell, b , and B.A. Wandell a  

E-print Network

sensitivity of the human eye for that color component. Third, the filtered images are transformed into the CIE the perceived quality of multi­level halftone images. Our com­ putations were based on a spatial color the discriminability of large uniform color patches. S­CIELAB includes a pre­processing stage that accounts for certain

Wandell, Brian A.


Principles of high-spatial-resolution surface EMG (HSR-EMG): single motor unit detection and application in the diagnosis of neuromuscular disorders  

Microsoft Academic Search

The most detailed information about the structural and functional characteristics of the muscle can be gained from the single motor unit (MU) action potential. In addition, information about the activity of a single MU is essential for the diagnosis of neuromuscular disorders. Due to the low spatial resolution of conventional bipolar surface electromyography (EMG), the resulting signal is a superposition

G Rau; C Disselhorst-Klug



Measuring the Contribution of Water and Green Space Amenities to Housing Values: An Application and Comparison of Spatially-weighted Hedonic Models  

Microsoft Academic Search

This study estimates the influence of proximity to water bodies and park amenities on residential housing values in Knox County, Tennessee, using the hedonic price approach. Values for proximity to water bodies and parks are first estimated globally with a standard ordinary least square (OLS) model. A locally weighted regression model is then employed to investigate spatial non-stationarity and generate

Seong-Hoon Cho; James Michael Bowker; William M. Park



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.


Spatial Aspects of Census Districting  

NASA Astrophysics Data System (ADS)

Urban districting refers to partitioning of an urban area into smaller regions for a specific application in order to effectively facilitate and enhance the quality of municipal services. Among other considerations, which are imposed by the general problem or the application in hand, several factors in urban districting have spatial aspects, many of which have been disregarded in most of districting plans, and only descriptive measures have been considered. This paper explores the impact of spatial aspects on census districting, as an important urban districting. It proposes an approach that not only considers the workload, as the most effective criterion in census districting, but spatial criteria such as compactness, barriers and travers length are also involved. The implementation results of the proposed approach for a case study have been evaluated and discussed.

Dezyani, S.; Karimipour, F.



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

NASA Astrophysics Data System (ADS)

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

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



Measuring boundary convexity at multiple spatial scales using a linear “moving window” analysis: an application to coastal river otter habitat selection  

Microsoft Academic Search

Landscape metrics have been used to quantify ecological patterns and to evaluate relationships between animal presence\\/abundance\\u000a and habitat at multiple spatial scales. However, many ecological flows occur in linear systems such as streams, or across\\u000a patch\\/landscape boundaries (ecotones). Some organisms and flows may depend on the boundary shape, but metrics for defining\\u000a linear boundary characteristics are scarce. While sinuosity and

Shannon E. AlbekeNathan; Nathan P. Nibbelink; Lan Mu; Daniel J. Ellsworth



A smoothed particle hydrodynamics-based fluid model with a spatially dependent viscosity: application to flow of a suspension with a non-Newtonian fluid matrix  

Microsoft Academic Search

A smoothed particle hydrodynamics approach is utilized to model a non-Newtonian fluid with a spatially varying viscosity.\\u000a In the limit of constant viscosity, this approach recovers an earlier model for Newtonian fluids of Español and Revenga (Phys\\u000a Rev E 67:026705, 2003). Results are compared with numerical solutions of the general Navier–Strokes equation using the “regularized” Bingham model\\u000a of Papanastasiou (J

Nicos S. Martys; William L. George; Byong-Wa Chun; Didier Lootens



Modeling the environmental suitability of recreational trails in the Sam Houston National Forest: an application of spatial technologies and the universal soil loss equation  

E-print Network

: Dr. Myron Floyd This study was an attempt to integrate spatial technologies, including Geographic Information Systems (GIS) and the Global Positioning System (GPS), with the Universal Soil Loss Equation (USLE). Through GIS, GPS, and the USLE... on these innovations, Canada's Ambassador to the Environment, John Fraser, stated "It is not an exaggeration to say that the future health of our planet depends upon our ability to make use of technologies such as GIS, GPS, and associated satellite linkages to find...

Holzer, Damon Michael



Estimating spatial correlations from spatial-temporal meteorological data  

SciTech Connect

Meterological data are collected over space and time. Techniques for modeling the temporal characteristics of meteorological data are well known and accepted. While methods for accommodating the spatial character of meteorological variables have been available for over 30 years, they are far less frequently uses. In part, this is because many theoretical and computational issues remain to be resolved concerning the application of spatial modeling methods to meterological data. One of these issues is the fitting of spatial-correlation functions. In this paper, it is shown that temporal correlations can seriously bias fitted covariance functions that are used in optimal interpolation and optimal spatial-averaging methods. A result of this bias is that the fitting of correlation functions to temporal correlations can result in overestimates of spatial correlations. In contrast, the fitting of structure function models from data for fixed time periods does not suffer from the temporal biases of correlation function fitting and should be the preferred method for estimating spatial correlations. Structure function modeling must, however, accommodate anisotropy in the data. 34 refs., 12 figs., 3 tabs.

Gunst, R.F. [Southern Methodist Univ., Dallas, TX (United States)] [Southern Methodist Univ., Dallas, TX (United States)



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

NASA Astrophysics Data System (ADS)

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

Legleiter, Carl J.



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


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



Spatial-Operator Algebra For Robotic Manipulators  

NASA Technical Reports Server (NTRS)

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

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



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


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



A spatially explicit risk approach to support marine spatial planning in the German EEZ.  


An ecosystem approach to marine spatial planning (MSP) promotes sustainable development by organizing human activities in a geo-spatial and temporal context. (1) This study develops and tests a spatially explicit risk assessment to support MSP. Using the German exclusive economic zone (EEZ) of the North Sea as a case study area, current and future spatial management scenarios are assessed. (2) Different tools are linked in order to carry out a comprehensive spatial risk assessment of current and future spatial management scenarios for ecologic and economic ecosystem components, i.e. Pleuronectes platessa nursery grounds. With the identification of key inputs and outputs the suitability of each tool is tested. (3) Here, the procedure as well as the main findings of the spatially explicit risk approach are summarised to demonstrate the applicability of the framework and the need for an ecosystem approach to risk management techniques using geo-spatial tools. PMID:23535014

Gimpel, Antje; Stelzenmüller, Vanessa; Cormier, Roland; Floeter, Jens; Temming, Axel



Approximate spatial reasoning  

NASA Technical Reports Server (NTRS)

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

Dutta, Soumitra




NSDL National Science Digital Library

The TeachSpatial collection assembles digital teaching resources relevant to spatial cognition, spatial learning, and spatial literacy across multiple STEM disciplines for middle school, high school, and undergraduate learners. Common topics include physical geography, GIS (Geographic Information Systems), and map reading skills (population demographics, geographic coordinates, etc.). Resources are indexed by the core spatial concepts and principles found in the 1996 National Science Education Standards and contain comments and ratings from a community of users. TeachSpatial is a project of the Center for Spatial Studies at the University of California, Santa Barbara.



Application of composite water quality identification index on the water quality evaluation in spatial and temporal variations: a case study in Honghu Lake, China.  


Composite Water Quality Identification Index (CWQII) and multivariate statistical techniques were used to investigate the temporal and spatial variations of water quality in Honghu Lake. The aims are to explore the characteristics of water quality trends in annual, monthly, and site spatial distribution and to identify the main pollution factors. The results showed that the values of CWQII increased from 2.0 to 4.0 from the years 2001 to 2005, then decreased from 2006 and kept a balance between 2.0 and 3.0 from 2006 to 2011, indicating that the water quality of Honghu Lake deteriorated from 2001 to 2005 and has gradually improved since 2006, which were likely achieved after water protection measurements taken since 2004. The monthly change rules of water quality were influenced by a superposition of natural processes and human activities. In samples numbered 1-9 from upstream to downstream, the maximum values of CWQII often occurred in sample site 9 while the minimum ones often occurred in sample site 2, indicating that the water quality near the upstream tributary was the poorest and that in the core zone was the best. Incoming water from the trunk canal of the Sihu area upstream was the largest pollution source. The sensitive pollution nutrients were mainly caused by the total nitrogen, followed by the total phosphorus. PMID:24615690

Ban, Xuan; Wu, Qiuzhen; Pan, Baozhu; Du, Yun; Feng, Qi




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.


Spatial Standard Observer  

NASA Technical Reports Server (NTRS)

The present invention relates to devices and methods for the measurement and/or for the specification of the perceptual intensity of a visual image, or the perceptual distance between a pair of images. Grayscale test and reference images are processed to produce test and reference luminance images. A luminance filter function is convolved with the reference luminance image to produce a local mean luminance reference image. Test and reference contrast images are produced from the local mean luminance reference image and the test and reference luminance images respectively, followed by application of a contrast sensitivity filter. The resulting images are combined according to mathematical prescriptions to produce a Just Noticeable Difference, JND value, indicative of a Spatial Standard Observer, SSO. Some embodiments include masking functions, window functions, special treatment for images lying on or near borders and pre-processing of test images.

Watson, Andrew B. (Inventor)



Spatial Standard Observer  

NASA Technical Reports Server (NTRS)

The present invention relates to devices and methods for the measurement and/or for the specification of the perceptual intensity of a visual image. or the perceptual distance between a pair of images. Grayscale test and reference images are processed to produce test and reference luminance images. A luminance filter function is convolved with the reference luminance image to produce a local mean luminance reference image . Test and reference contrast images are produced from the local mean luminance reference image and the test and reference luminance images respectively, followed by application of a contrast sensitivity filter. The resulting images are combined according to mathematical prescriptions to produce a Just Noticeable Difference, JND value, indicative of a Spatial Standard Observer. SSO. Some embodiments include masking functions. window functions. special treatment for images lying on or near border and pre-processing of test images.

Watson, Andrw B. (Inventor)



Center for Advanced Spatial Technologies  

NSDL National Science Digital Library

The Center for Advanced Spatial Technologies (CAST) at the University of Arkansas is dedicated to applications in Geographic Information Systems (GIS), remote sensing, digital photogrammetry and interoperability, and Global Positioning Systems (GPS). This enormous site contains a wide range of research activities in spatial technologies as applied to the disciplines of environmental studies, archaeology, historical preservation, landscape architecture, urban and rural planning, spatial statistics, and data development. Within the Reports and Publications section, the Arkansas Gap Analysis Program (GAP) final report is available (in HTML and .pdf formats) and, though the work itself was completed in 1998, the report provides excellent information on biodiversity assessment and land-cover mapping (For the national Gap Analysis Program Website, see the September 17, 1997 Scout Report for Science & Engineering). Each of the research areas of the site contains documentation of projects and links to related sites.



Policy applications of a highly resolved spatial and temporal onroad carbon dioxide emissions data product for the U.S.: Analyses and their implications for mitigation  

NASA Astrophysics Data System (ADS)

Onroad CO2 emissions were analyzed as part of overall GHG emissions, but those studies have suffered from one or more of these five shortcomings: 1) the spatial resolution was coarse, usually encompassing a region, or the entire U.S.; 2) the temporal resolution was coarse (annual or monthly); 3) the study region was limited, usually a metropolitan planning organization (MPO) or state; 4) fuel sales were used as a proxy to quantify fuel consumption instead of focusing on travel; 5) the spatial heterogeneity of fleet and road network composition was not considered and instead national averages are used. Normalized vehicle-type state-level spatial biases range from 2.6% to 8.1%, while the road type classification biases range from -6.3% to 16.8%. These biases are found to cause errors in reduction estimates as large as ±60%, corresponding to ±0.2 MtC, for a national-average emissions mitigation strategy focused on a 10% emissions reduction from a single vehicle class. Temporal analysis shows distinct emissions seasonality that is particularly visible in the northernmost latitudes, demonstrating peak-to-peak deviations from the annual mean of up to 50%. The hourly structure shows peak-to-peak deviation from a weekly average of up to 200% for heavy-duty (HD) vehicles and 140% for light-duty (LD) vehicles. The present study focuses on reduction of travel and fuel economy improvements by putting forth several mitigation scenarios aimed at reducing VMT and increasing vehicle fuel efficiency. It was found that the most effective independent reduction strategies are those that increase fuel efficiency by extending standards proposed by the corporate average fuel economy (CAFE) or reduction of fuel consumption due to price increases. These two strategies show cumulative emissions reductions of approximately 11% and 12%, respectively, from a business as usual (BAU) approach over the 2000-2050 period. The U.S. onroad transportation sector is long overdue a comprehensive study of CO2 emissions at a highly resolved level. Such a study would improve fossil fuel flux products by enhancing measurement accuracy and prompt location-specific mitigation policy. The carbon cycle science and policymaking communities are both poised to benefit greatly from the development of a highly resolved spatiotemporal emissions product.

Mendoza Lebrun, Daniel


Chapter Title Fundamentals of Spatial Data Warehousing for Geographic Knowledge Discovery  

E-print Network

Recent years have witnessed major changes in the Geographic Information (GI) market, from interoperable decision making, such as dashboards, executive information systems, data mining, report makers, and OLAP (On-Line Analytical Processing). In fact, data warehouse emerged as the unifying solution to a series


Differentiating spatial memory from spatial transformations.  


The perspective-taking task is one of the most common paradigms used to study the nature of spatial memory, and better performance for certain orientations is generally interpreted as evidence of spatial representations using these reference directions. However, performance advantages can also result from the relative ease in certain transformations/rotations. To differentiate spatial memory from spatial transformations, the present study took a new approach based on the hypothesis that responses may be biased toward the original representation but not a transformed one. Participants memorized a regular target array and then judged the relative direction between 2 targets while imagining facing various directions. Their response time and absolute errors showed the standard advantages at 4 imagined orientations. In contrast, an attraction analysis suggested that only 1 orientation was represented in memory, whereas performance advantages at other orthogonal orientations were due to lower transformation costs and should not be interpreted as spatial representations. These findings challenged the traditional performance-based interpretations of perspective change tasks and provided a new research paradigm to differentiate spatial representations from spatial transformations. PMID:24364722

Street, Whitney N; Wang, Ranxiao Frances




Microsoft Academic Search

The spatial auto-regression (SAR) model is a popula r spatial data analysis technique which has been used in many applications with geo-spatial datasets. Howeve r, exact solutions for estimating SAR parameters are computationally expensive due to the need to compute all the eigen-values of a very large matrix . Therefore, serial solutions for the SAR model do not scale up

Shashi Shekhar; Baris M. Kazar; David J. Lilja


Part II: temporal and spatial distribution of multiclass pesticide residues in lake sediments of northern Greece: application of an optimized MAE-LC-MS/MS pretreatment and analytical method.  


The development and application of an analytical methodology for the pretreatment and determination of 253 multiclass pesticides, in lake sediment samples, using liquid chromatography coupled with mass spectrometry (LC-MS/MS) are described in this work. Sediments of lakes Volvi, Doirani, and Kerkini, located in northern Greece, were collected in two-time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methodology. Microwave-assisted extraction (MAE) was applied to extract the pesticide residues from lake sediment samples. Analytical results were stored, categorized, and visualized using geographical information systems, in order to assess and observe spatial and temporal variations of the pollution. Main pesticides that were detected included the following: amitrole, tebuconazole, phoxim, diniconazole, sethoxydim, temephos, tetrachlorvinphos, pendimethalin, boscalid, disulfoton sulfone, lenacil, propiconazole, cycloxydim, pyridaben, and terbuthylazine. Amitrole, diniconazole, and tebuconazole were found to be common in all three lakes. Lakes Kerkini and Doirani exhibited increased concentrations during the first sampling period (winter 2010) with predominant pesticide classes, triazines/triazoles and organophosphates. Pollution is mainly located near the populated villages of the lakes and the nearby cultivations. During the second sampling period, pesticide concentrations appear lower and located in sediments near the center of the lake. Lake Volvi exhibits increased pesticide concentrations during the second sampling period, temporal and spatial variations and different pesticide profile pattern. Increased pollution occurs near the center of the lake during the first sampling period, mainly comprised by triazines/triazoles and organophosphates. During the second sampling period, the majority of the sediment samples demonstrated a different pesticide profile dominated by unclassified pesticides and triazines/triazoles. Mineralogical analysis of the samples demonstrates that sediments are mainly composed of clay, mud, and sand particles, and they present spatial variations. Near the center of the lakes, sediments appear to be more fine-grained with higher clay content and are more likely to adsorb pesticides. PMID:24691934

Kalogridi, Eleni-Chrysoula; Christophoridis, Christophoros; Bizani, Erasmia; Drimaropoulou, Garyfallia; Fytianos, Konstantinos



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



A software tool to model genetic regulatory networks. Applications to the modeling of threshold phenomena and of spatial patterning in Drosophila.  


We present a general methodology in order to build mathematical models of genetic regulatory networks. This approach is based on the mass action law and on the Jacob and Monod operon model. The mathematical models are built symbolically by the Mathematica software package GeneticNetworks. This package accepts as input the interaction graphs of the transcriptional activators and repressors of a biological process and, as output, gives the mathematical model in the form of a system of ordinary differential equations. All the relevant biological parameters are chosen automatically by the software. Within this framework, we show that concentration dependent threshold effects in biology emerge from the catalytic properties of genes and its associated conservation laws. We apply this methodology to the segment patterning in Drosophila early development and we calibrate the genetic transcriptional network responsible for the patterning of the gap gene proteins Hunchback and Knirps, along the antero-posterior axis of the Drosophila embryo. In this approach, the zygotically produced proteins Hunchback and Knirps do not diffuse along the antero-posterior axis of the embryo of Drosophila, developing a spatial pattern due to concentration dependent thresholds. This shows that patterning at the gap genes stage can be explained by the concentration gradients along the embryo of the transcriptional regulators. PMID:20523731

Dilão, Rui; Muraro, Daniele



Kinetic theory of spatially homogeneous systems with long-range interactions: III. Application to power law potentials, plasmas, stellar systems, and to the HMF model  

NASA Astrophysics Data System (ADS)

We apply the general results of the kinetic theory of systems with long-range interactions to particular systems of physical interest. We consider repulsive and attractive power law potentials of interaction with in a space of dimension d . For , strong collisions must be taken into account and the evolution of the system is governed by the Boltzmann equation or by a modified Landau equation; for , strong collisions are negligible and the evolution of the system is governed by the Lenard-Balescu equation. In the marginal case , we can use the Landau equation (with appropriately justified cut-offs) as a relevant approximation of the Boltzmann and Lenard-Balescu equations. The divergence at small scales that appears in the original Landau equation is regularized by the effect of strong collisions. In the case of repulsive interactions with a neutralizing background ( e.g. plasmas), the divergence at large scales that appears in the original Landau equation is regularized by collective effects accounting for Debye shielding. In the case of attractive interactions ( e.g. gravity), it is regularized by the spatial inhomogeneity of the system and its finite extent. We provide explicit analytical expressions of the diffusion and friction coefficients, and of the relaxation time, depending on the value of the exponent and on the dimension of space d . We treat in a unified framework the case of Coulombian plasmas and stellar systems in various dimensions of space, and the case of the attractive and repulsive HMF models.

Chavanis, Pierre-Henri



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.



Spatial Solitons in Algaas Waveguides  

NASA Astrophysics Data System (ADS)

In this work, by measuring the two-, three-photon absorption, and the nonlinear refractive index coefficients, a useful bandwidth for an all-optical switching applications in the AlGaAs below half the band gap is identified. Operating in this material system, several types of spatial solitons such as fundamental bright solitons, Vector solitons, and Manakov solitons are experimentally demonstrated. The propagation and the interaction behaviors of these solitons are studied experimentally and numerically. The distinct properties of each soliton are discussed along with some possible applications. Some applications, such as all -optical switching based on spatial soliton dragging and the efficient guiding of orthogonally polarized femtosecond pulses by a bright spatial soliton, are experimentally demonstrated. The signal gain due to an ultrafast polarization coupling, better known as Four Wave Mixing (FWM) is demonstrated in a channel waveguide. The effects of FWM are studied experimentally and numerically. This effect is also used to demonstrate polarization switching. The linear and nonlinear properties of AlGaAs/GaAs multiple quantum well waveguides are measured. Anisotropic two photon absorption and nonlinear refractive indices near half the band gap are measured along with the linear birefringence for several different quantum well structures. The usefulness of multiple quantum well structures for an all -optical switching because of anisotropic nature of this material system is discussed.

Kang, Jin Ung


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 of…

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


Spatial recurrence plots  

Microsoft Academic Search

We propose an extension of the recurrence plot concept to perform quantitative analyzes of roughness and disorder of spatial patterns at a fixed time. We introduce spatial recurrence plots SRPs as a graphical representation of the pointwise correlation matrix, in terms of a two-dimensional spatial return plot. This technique is applied to the study of complex patterns generated by coupled

D. B. Vasconcelos; S. R. Lopes; R. L. Viana; J. Kurths



Complex Spatial Query Processing  

Microsoft Academic Search

The user of a Geographical Information System is not limited to conventional spatial selections and joins, but may also pose more complicated and descriptive queries. In this paper we focus on the efficient processing and optimization of complex spatial queries that involve combinations of spatial selections and joins. Our contribution is manifold; we first provide formulae that accurately estimate the

Nikos Mamoulis; Dimitris Papadias; Dinos Arkoumanis



Efficient method for controlling the spatial coherence of a laser  

E-print Network

- hibiting very high spatial coherence and thermal sources or light emitting diodes (LEDs) having very low coherence [11], and the ones engineered for low spatial coherence were incorporated in full-field imaging applications to obtain images whose quality is similar to those obtained with traditional low spatial coherence

Cao, Hui


Application of a spatially distributed water balance model for assessing surface water and groundwater resources in the Geba basin, Tigray, Ethiopia  

NASA Astrophysics Data System (ADS)

The Geba basin is one of the most water-stressed areas of Ethiopia, with only a short rainy period from mid-June to mid-September. Because rainfall in this region has been consistently erratic in the last decades, both in time and space, rain-fed agriculture has become problematic. Hence, in order to supplement rain-fed agriculture by irrigation, a detailed understanding of local and regional surface water and groundwater resources is important. The main objective of this study is to assess the available water resources in the Geba basin using a spatially distributed water balance model (WetSpass). Relevant input data for the model is prepared in the form of digital maps using remote sensing images, GIS tools, FAO and NASA databases, field reconnaissance and processing of meteorological and hydrological observations. The model produces digital maps of long-term average, seasonal and annual surface runoff, evapotranspiration and groundwater recharge. Results of the model show that 76% of the precipitation in the basin is lost through evapotranspiration, 18% becomes surface runoff and only 6% recharges the groundwater system. Model predictions are verified against river flow observations and are shown to be reliable. Additional maps are derived of accumulated surface runoff, safe yield for groundwater abstraction and water deficit for crop growth. Comparison of existing reservoirs with the accumulated runoff map shows that many reservoirs have failed because their design capacity is much higher than the actual inflow. Comparison of the safe yield map with the crop water deficit map shows that in most areas groundwater can be safely abstracted to supplement the water deficit for crop growth during the wet summer season. However, in the dry winter season the crop water deficit is too high to be supplemented by groundwater abstraction in a sustainable way.

Gebreyohannes, Tesfamichael; De Smedt, Florimond; Walraevens, Kristine; Gebresilassie, Solomon; Hussien, Abdelwasie; Hagos, Miruts; Amare, Kasa; Deckers, Jozef; Gebrehiwot, Kindeya



Spatially-Heterodyned Holography  


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



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

NASA Astrophysics Data System (ADS)

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

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


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



Spatial Data Models and Query Processing Hanan Samet  

E-print Network

the term database management system DBMS was a euphemism for distinguishing commercial applications e. The common thread behind all of these applications is that they make use of spatial data. Spatial data is a term used to describe data that pertains to the space occupied by objects in a databases. This data

Samet, Hanan


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



Spatial Latent Class Analysis Model for Spatially Distributed Multivariate Binary Data  

PubMed Central

A spatial latent class analysis model that extends the classic latent class analysis model by adding spatial structure to the latent class distribution through the use of the multinomial probit model is introduced. Linear combinations of independent Gaussian spatial processes are used to develop multivariate spatial processes that are underlying the categorical latent classes. This allows the latent class membership to be correlated across spatially distributed sites and it allows correlation between the probabilities of particular types of classes at any one site. The number of latent classes is assumed fixed but is chosen by model comparison via cross-validation. An application of the spatial latent class analysis model is shown using soil pollution samples where 8 heavy metals were measured to be above or below government pollution limits across a 25 square kilometer region. Estimation is performed within a Bayesian framework using MCMC and is implemented using the OpenBUGS software. PMID:20161235

Wall, Melanie M.; Liu, Xuan




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.



Part I: temporal and spatial distribution of multiclass pesticide residues in lake waters of Northern Greece: application of an optimized SPE-UPLC-MS/MS pretreatment and analytical method.  


The present work describes the application of an analytical procedure, utilizing ultra performance liquid chromatography (UPLC) coupled with mass spectrometry instrumentation, for the determination of 253 multiclass pesticides, classified in six different groups. Solid phase extraction was applied for the isolation and pre-concentration of target compounds in water samples. Surface waters of the lakes located in Northern Greece (Volvi, Doirani, and Kerkini), were collected in two time periods (fall/winter 2010 and spring/summer 2011) and analyzed, applying the developed analytical methods. Spatial distribution of detected pesticides was visualized using interpolation methods and geographical information systems (GIS). Pesticides with maximum concentrations were amitrole, propoxur, simazine, chlorpyrifos, carbendazim, triazophos, disulfoton-sulfone, pyridaben, sebuthylazine, terbuthylazine, atrazine, atrazine-desethyl, bensulfuron-methyl, metobromuron, metribuzin, rotenone, pyriproxyfen, and rimsulfuron. In Lake Kerkini, mainly carbamates and triazines were determined at elevated concentrations, near the coastal point of the NW side of the lake. Seasonal variations were strong among the applied pesticide classes and determined concentrations, indicating the contribution of pesticide application patterns and rainfall. Lake Doirani exhibited organophosphate pesticides at higher concentrations mainly at coastal points, while triazines emerged as the main pollutant during spring sampling. Lake Volvi exhibited the highest pesticide concentrations, mostly triazines and ureas at the central part of the lake. The occurrence of extreme values and nonconstant seasonal variations indicated that the concentrations were increased disproportionately during the second sampling, as a result of the varying contribution of pollution sources right after the application period. In all cases, the total concentration of pesticides increased during the second sampling period. PMID:24696214

Kalogridi, Eleni-Chrysoula; Christophoridis, Christophoros; Bizani, Erasmia; Drimaropoulou, Garyfallia; Fytianos, Konstantinos



Minimising Mortality in Endangered Raptors Due to Power Lines: The Importance of Spatial Aggregation to Optimize the Application of Mitigation Measures  

PubMed Central

Electrocution by power lines is one of the main causes of non-natural mortality in birds of prey. In an area in central Spain, we surveyed 6304 pylons from 333 power lines to determine electrocution rates, environmental and design factors that may influence electrocution and the efficacy of mitigation measures used to minimise electrocution cases. A total of 952 electrocuted raptors, representing 14 different species, were observed. Electrocuted raptors were concentrated in certain areas and the environmental factors associated with increased electrocution events were: greater numbers of prey animals; greater vegetation cover; and shorter distance to roads. The structural elements associated with electrocutions were shorter strings of insulators, one or more phases over the crossarm, cross-shaped design and pylon function. Of the 952 carcasses found, 148 were eagles, including golden eagle (Aquila chrysaetos), Spanish imperial eagle (Aquila adalberti) and Bonelli's eagle (Aquila fasciata). Electrocuted eagles were clustered in smaller areas than other electrocuted raptors. The factors associated with increased eagle electrocution events were: pylons function, shorter strings of insulators, higher slopes surrounding the pylon, and more numerous potential prey animals. Pylons with increased string of insulators had lower raptor electrocution rates than unimproved pylons, although this technique was unsuccessful for eagles. Pylons with cable insulation showed higher electrocution rates than unimproved pylons, both for raptors and eagles, despite this is the most widely used and recommended mitigation measure in several countries. To optimize the application of mitigation measures, our results recommend the substitution of pin-type insulators to suspended ones and elongating the strings of insulators. PMID:22140549

Guil, Francisco; Fernandez-Olalla, Mariana; Moreno-Opo, Ruben; Mosqueda, Ignacio; Gomez, Maria Elena; Aranda, Antonio; Arredondo, Angel; Guzman, Jose; Oria, Javier; Gonzalez, Luis Mariano; Margalida, Antoni



Minimising mortality in endangered raptors due to power lines: the importance of spatial aggregation to optimize the application of mitigation measures.  


Electrocution by power lines is one of the main causes of non-natural mortality in birds of prey. In an area in central Spain, we surveyed 6304 pylons from 333 power lines to determine electrocution rates, environmental and design factors that may influence electrocution and the efficacy of mitigation measures used to minimise electrocution cases. A total of 952 electrocuted raptors, representing 14 different species, were observed. Electrocuted raptors were concentrated in certain areas and the environmental factors associated with increased electrocution events were: greater numbers of prey animals; greater vegetation cover; and shorter distance to roads. The structural elements associated with electrocutions were shorter strings of insulators, one or more phases over the crossarm, cross-shaped design and pylon function. Of the 952 carcasses found, 148 were eagles, including golden eagle (Aquila chrysaetos), Spanish imperial eagle (Aquila adalberti) and Bonelli's eagle (Aquila fasciata). Electrocuted eagles were clustered in smaller areas than other electrocuted raptors. The factors associated with increased eagle electrocution events were: pylons function, shorter strings of insulators, higher slopes surrounding the pylon, and more numerous potential prey animals. Pylons with increased string of insulators had lower raptor electrocution rates than unimproved pylons, although this technique was unsuccessful for eagles. Pylons with cable insulation showed higher electrocution rates than unimproved pylons, both for raptors and eagles, despite this is the most widely used and recommended mitigation measure in several countries. To optimize the application of mitigation measures, our results recommend the substitution of pin-type insulators to suspended ones and elongating the strings of insulators. PMID:22140549

Guil, Francisco; Fernández-Olalla, Mariana; Moreno-Opo, Rubén; Mosqueda, Ignacio; Gómez, María Elena; Aranda, Antonio; Arredondo, Angel; Guzmán, José; Oria, Javier; González, Luis Mariano; Margalida, Antoni



Approximate Computation of Multidimensional Aggregates of Sparse Data Using Wavelets  

Microsoft Academic Search

Computing multidimensional aggregates in high dimensionsis a performance bottleneck for many OLAP applications.Obtaining the exact answer to an aggregation query can beprohibitively expensive in terms of time and\\/or storage spacein a data warehouse environment. It is advantageous to havefast, approximate answers to OLAP aggregation queries.In this paper, we present a novel method that providesapproximate answers to high-dimensional OLAP aggregationqueries in

Jeffrey Scott Vitter; Min Wang




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.


Spatial Learning in Dragonflies  

E-print Network

about spatial memory in females than in males. This may bemales and females may result in interesting and potentially instructive sexual differences in spatial learning and memory.the limit of a male’s memory for a female morph is less than

Eason, Perri K; Switzer, Paul V.



Toward intelligent spatial information dissemination based on user profile model  

NASA Astrophysics Data System (ADS)

Spatial information dissemination is a necessary step to make use of spatial information for which is a bridge between the acquirement and the application of spatial information. However, conventional methods of spatial information dissemination cannot cater to users in that not only users' personalized requirements cannot be satisfied, but initiative dissemination service cannot be provided. In this paper, the idea of intelligent spatial information dissemination (ISD) is proposed. Combining the ideas of personalized information retrieval, information filtering and recommender systems, the ISD system employs user profiles and query conditions to provide two implement ways of spatial information disseminations, namely "pull" and "push". Then, the three layers architecture of intelligent spatial information dissemination system based on user profile model is given, and the procedure of data in the ISD system is introduced. Also, the user profile is presented including user profile model and user profile management. Finally, the prototype system of intelligent spatial information dissemination is presented.

Xia, Yu; Zhu, Xinyan; Zhang, Chunlin; He, Jie



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



Applications of virtual audio  

Microsoft Academic Search

Technology for electronically simulating spatial sound over loudspeakers and headphones has matured in the past few decades to facilitate many new applications of virtual audio. Electronic simulation of directional and distance auditory cues has greatly expanded the areas of application of virtual audio. Some potential aerospace applications include monitoring spatially separated speech communication signals to increase understanding, navigating by an

Mark Ericson; William D'Angelo; Eric Scarborough; Steve Rogers; Philip Amburn; Dennis Ruck



Entropy, complexity, and spatial information  

NASA Astrophysics Data System (ADS)

We pose the central problem of defining a measure of complexity, specifically for spatial systems in general, city systems in particular. The measures we adopt are based on Shannon's (in Bell Syst Tech J 27:379-423, 623-656, 1948) definition of information. We introduce this measure and argue that increasing information is equivalent to increasing complexity, and we show that for spatial distributions, this involves a trade-off between the density of the distribution and the number of events that characterize it; as cities get bigger and are characterized by more events—more places or locations, information increases, all other things being equal. But sometimes the distribution changes at a faster rate than the number of events and thus information can decrease even if a city grows. We develop these ideas using various information measures. We first demonstrate their applicability to various distributions of population in London over the last 100 years, then to a wider region of London which is divided into bands of zones at increasing distances from the core, and finally to the evolution of the street system that characterizes the built-up area of London from 1786 to the present day. We conclude by arguing that we need to relate these measures to other measures of complexity, to choose a wider array of examples, and to extend the analysis to two-dimensional spatial systems.

Batty, Michael; Morphet, Robin; Masucci, Paolo; Stanilov, Kiril



Entropy, complexity, and spatial information  

NASA Astrophysics Data System (ADS)

We pose the central problem of defining a measure of complexity, specifically for spatial systems in general, city systems in particular. The measures we adopt are based on Shannon's (in Bell Syst Tech J 27:379-423, 623-656, 1948) definition of information. We introduce this measure and argue that increasing information is equivalent to increasing complexity, and we show that for spatial distributions, this involves a trade-off between the density of the distribution and the number of events that characterize it; as cities get bigger and are characterized by more events—more places or locations, information increases, all other things being equal. But sometimes the distribution changes at a faster rate than the number of events and thus information can decrease even if a city grows. We develop these ideas using various information measures. We first demonstrate their applicability to various distributions of population in London over the last 100 years, then to a wider region of London which is divided into bands of zones at increasing distances from the core, and finally to the evolution of the street system that characterizes the built-up area of London from 1786 to the present day. We conclude by arguing that we need to relate these measures to other measures of complexity, to choose a wider array of examples, and to extend the analysis to two-dimensional spatial systems.

Batty, Michael; Morphet, Robin; Masucci, Paolo; Stanilov, Kiril



Spatially branched hierarchical ZnO nanorod-TiO2 nanotube array heterostructures for versatile photocatalytic and photoelectrocatalytic applications: towards intimate integration of 1D-1D hybrid nanostructures.  


Hierarchically ordered ZnO nanorods (NRs) decorated nanoporous-layer-covered TiO2 nanotube array (ZnO NRs/NP-TNTAs) nanocomposites have been prepared by an efficient, two-step anodization route combined with an electrochemical deposition strategy, by which monodispersed one-dimensional (1D) ZnO NRs were uniformly grown on the framework of NP-TNTAs. The crystal phases, morphologies, optical properties, photocatalytic as well as photoelectrocatalytic performances of the well-defined ZnO NRs/NP-TNTAs heterostructures were systematically explored to clarify the structure-property correlation. It was found that the ZnO NRs/NP-TNTAs heterostructure exhibits significantly enhanced photocatalytic and photoelectrocatalytic performances, along with favorable photostability toward degradation of organic pollutants under UV light irradiation, as compared to the single component counterparts. The remarkably enhanced photoactivity of ZnO NRs/NP-TNTAs heterostructure is ascribed to the intimate interfacial integration between ZnO NRs and NP-TNTAs substrate imparted by the unique spatially branched hierarchical structure, thereby contributing to the efficient transfer and separation of photogenerated electron-hole charge carriers. Moreover, the specific active species during the photocatalytic process was unambiguously determined and photocatalytic mechanism was tentatively presented. It is anticipated that our work could provide new insights for the construction of various hierarchical 1D-1D hybrid nanocomposites for extensive photocatalytic applications. PMID:25363649

Xiao, Fang-Xing; Hung, Sung-Fu; Tao, Hua Bing; Miao, Jianwei; Yang, Hong Bin; Liu, Bin



Spatial Light Amplifier Modulators  

NASA Technical Reports Server (NTRS)

Spatial light amplifier modulators (SLAM's) are conceptual devices that effect two-dimensional spatial modulation in optical computing and communication systems. Unlike current spatial light modulators, these provide gain. Optical processors incorporating SLAM's designed to operate in reflection or transmission mode. Each element of planar SLAM array is optical amplifier - surface-emitting diode laser. Array addressed electrically with ac modulating signals superimposed on dc bias currents supplied to lasers. SLAM device provides both desired modulation and enough optical gain to enable splitting of output signal into many optical fibers without excessive loss of power.

Eng, Sverre T.; Olsson, N. Anders



Architectural Implications for Spatial Object Association Algorithms  

SciTech Connect

Spatial object association, also referred to as cross-match of spatial datasets, is the problem of identifying and comparing objects in two or more datasets based on their positions in a common spatial coordinate system. In this work, we evaluate two crossmatch algorithms that are used for astronomical sky surveys, on the following database system architecture configurations: (1) Netezza Performance Server R, a parallel database system with active disk style processing capabilities, (2) MySQL Cluster, a high-throughput network database system, and (3) a hybrid configuration consisting of a collection of independent database system instances with data replication support. Our evaluation provides insights about how architectural characteristics of these systems affect the performance of the spatial crossmatch algorithms. We conducted our study using real use-case scenarios borrowed from a large-scale astronomy application known as the Large Synoptic Survey Telescope (LSST).

Kumar, V S; Kurc, T; Saltz, J; Abdulla, G; Kohn, S R; Matarazzo, C



A spatial light modulator for terahertz beams  

SciTech Connect

Spatial light modulators that control the spatial transmission of a terahertz beam either electrically or optically, have been difficult to build due to the lack of suitable materials. Here we propose the use of active terahertz metamaterials for the construction of a multi-pixel spatial modulator for terahertz beams. Our first-generation device consists of a 4 x 4 pixel array, where each pixel is an array of sub-wavelength-sized split-ring resonator elements fabricated on a semiconductor substrate, and is independently controlled by applying an external voltage. Through terahertz transmission experiments, we show that the spatial modulator has a uniform modulation depth of around 40 percent across all pixels at the resonant frequency. Around this operating frequency, the crosstalk between pixels is negligible. This device can operate under small voltage levels, at room temperature, with low power consumption and reasonably high switching speed, and can therefore benefit future applications in terahertz imaging and communications.

Chen, Hou-tong [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory



Spatially confined assembly of nanoparticles.  


Conspectus The ability to assemble NPs into ordered structures that are expected to yield collective physical or chemical properties has afforded new and exciting opportunities in the field of nanotechnology. Among the various configurations of nanoparticle assemblies, two-dimensional (2D) NP patterns and one-dimensional (1D) NP arrays on surfaces are regarded as the ideal assembly configurations for many technological devices, for example, solar cells, magnetic memory, switching devices, and sensing devices, due to their unique transport phenomena and the cooperative properties of NPs in assemblies. To realize the potential applications of NP assemblies, especially in nanodevice-related applications, certain key issues must still be resolved, for example, ordering and alignment, manipulating and positioning in nanodevices, and multicomponent or hierarchical structures of NP assemblies for device integration. Additionally, the assembly of NPs with high precision and high levels of integration and uniformity for devices with scaled-down dimensions has become a key and challenging issue. Two-dimensional NP patterns and 1D NP arrays are obtained using traditional lithography techniques (top-down strategies) or interfacial assembly techniques (bottom-up strategies). However, a formidable challenge that persists is the controllable assembly of NPs in desired locations over large areas with high precision and high levels of integration. The difficulty of this assembly is due to the low efficiency of small features over large areas in lithography techniques or the inevitable structural defects that occur during the assembly process. The combination of self-assembly strategies with existing nanofabrication techniques could potentially provide effective and distinctive solutions for fabricating NPs with precise position control and high resolution. Furthermore, the synergistic combination of spatially mediated interactions between nanoparticles and prestructures on surfaces may play an increasingly important role in the controllable assembly of NPs. In this Account, we summarize our approaches and progress in fabricating spatially confined assemblies of NPs that allow for the positioning of NPs with high resolution and considerable throughput. The spatially selective assembly of NPs at the desired location can be achieved by various mechanisms, such as, a controlled dewetting process, electrostatically mediated assembly of particles, and confined deposition and growth of NPs. Three nanofabrication techniques used to produce prepatterns on a substrate are summarized: the Langmuir-Blodgett (LB) patterning technique, e-beam lithography (EBL), and nanoimprint lithography (NPL). The particle density, particle size, or interparticle distance in NP assemblies strongly depends on the geometric parameters of the template structure due to spatial confinement. In addition, with smart design template structures, multiplexed NPs can be assembled into a defined structure, thus demonstrating the structural and functional complexity required for highly integrated and multifunction applications. PMID:25244100

Jiang, Lin; Chen, Xiaodong; Lu, Nan; Chi, Lifeng



Spatial decision support system for tobacco enterprise based on spatial data mining  

NASA Astrophysics Data System (ADS)

Tobacco enterprise is a special enterprise, which has strong correlation to regional geography. But in the past research and application, the combination between tobacco and GIS is limited to use digital maps to assist cigarette distribution. How to comprehensively import 3S technique and spatial data mining (SDM) to construct spatial decision support system (SDSS) of tobacco enterprise is the main research aspect in this paper. The paper concretely analyzes the GIS requirements in tobacco enterprise for planning location of production, monitoring production management and product sale at the beginning. Then holistic solution is presented and frame design for tobacco enterprise spatial decision based on SDM is given. This paper describes how to use spatial analysis and data mining to realize the spatial decision processing such as monitoring tobacco planted acreage, analyzing and planning the cigarette sale network and so on.

Mei, Xin; Liu, Junyi; Zhang, Xuexia; Cui, Weihong



Geo-spatial image analysis applications  

NASA Astrophysics Data System (ADS)

Recent advances in the field of spectral sensing technology have elucidated the benefits of multispectral and hyperspectral sensing the military and civil user community. These advancements, when properly exploited can provide the additional and improved automated terrain analysis, image understanding, object detection, and material characterization capabilities. the U.S. Army has established a Center of Excellence for Spectral Sensing Technology. This Center conducts collaborative research on, and development and demonstration of spectral sensing, processing and exploitation techniques. The Center's collaborative efforts integrate programs across multiple disciplines and form a baseline program consisting of coordinated technology thrusts. Existing efforts span the domains of sensor hardware, data processing architectures, algorithms, and signal processing and exploitation technologies across wide spectral regions. These thrusts in turn enable progress and performance improvement in the automated analysis, understanding, classification, discrimination, and identification of terrestrial objects, and materials. The participants draw upon common scientific processes and disciplines to approach similar problems related to different categories and domains of phenomenology.

Roper, William E.



Bayesian multivariate spatial models and their applications  

E-print Network

as to style and content by: Bani K. Mallick (Chair of Committee) Marina Vannucci (Member) Shaw-Pin Miaou (Member) Jeffrey D. Hart (Member) Yalchin Efendiev (Member) Michael T. Longnecker (Head of Department) August 2004 Major Subject: Statistics iii ABSTRACT... D. Hart, Dr. Marina Van- nucci, and Dr. Yalchin Efendiev for their insightful suggestions and help. I would like to extend a special thank you to Dr. Shaw-Pin Miaou, who has been a committee member and a great mentor and friend to me. I cannot...

Song, Joon Jin



Mapping spatial relations  

E-print Network

One of the fundamental issues in cognitive science is the problem of grounding concepts in the perceptual world. In this thesis, I present a computational theory for how spatial relations are grounded in the perceptual ...

Kasturirangan, Rajesh, 1971-




Microsoft Academic Search

Spatial variability in crop production occurs as a result of spatial and temporal variations in soil structure and fertility; soil physical, chemical and hydraulic properties; irrigation applications; pests and diseases; and plant genetics. It is argued that this variability can be managed and the efficiency of irrigation water use increased by spatially variable application of irrigation water to meet the

R. J. Smith; S. R. Raine; A. C. McCarthy; N. H. Hancock


An API for Integrating Spatial Context Models with Spatial Reasoning Algorithms  

Microsoft Academic Search

The integration of context-aware applications with spatial context models is often done using a common query language. However, algorithms that estimate and reason about spatial context information can benefit from a tighter integration. An object-oriented API makes such integration possible and can help reduce the complexity of algorithms making them easier to maintain and develop. This paper propose an object-oriented

Mikkel Baun Kjærgaard; Aarhus N



Grounding language in spatial routines  

E-print Network

This thesis describes a spatial language understanding system based on a lexicon of words defined in terms of spatial routines. A spatial routine is a script composed from a set of primitive operations on sensor data, ...

Tellex, Stefanie, 1980-



2009 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics October 18-21, 2009, New Paltz, NY MULTIZONE 2D SOUNDFIELD REPRODUCTION VIA SPATIAL BAND STOP FILTERS  

E-print Network

, New Paltz, NY MULTIZONE 2D SOUNDFIELD REPRODUCTION VIA SPATIAL BAND STOP FILTERS Yan Jennifer Wu-zone soundfield. Index Terms-- soundfield reproduction, multizone, cylindri- cal harmonic expansions, spatial band stop filters. 1. INTRODUCTION Reproduction of multiple independent soundfields in separate zones over

Abhayapala, Thushara D.


Microscopic Origin of Spatial Coherence and Wolf Shifts  

E-print Network

We show that the vacuum of electromagnetic field has intrinsic partial spatial coherence in frequency domain which effectively extends over regions of the order of wavelength $\\lambda$. This spatial coherence leads to a dynamical coupling between atoms and is the cause of source correlations and Wolf shifts. We show how the source spatial correlations can lead to tailor made coherent emissions. We discuss the universality of source correlation effects and presents several application.

Girish S. Agarwal



Spatial and temporal interactions of sympatric mountain lions in Arizona  

Microsoft Academic Search

Spatial and temporal interactions among individual members of populations can have direct applications to habitat management\\u000a of mountain lions (Puma concolor). Our objectives were to evaluate home range overlap and spatial\\/temporal use of overlap zones (OZ) of mountain lions in\\u000a Arizona. We incorporated spatial data with genetic analyses to assess relatedness between mountain lions with overlapping\\u000a home ranges. We recorded

Kerry L. Nicholson; Paul R. Krausman; Adrian Munguia-Vega; Melanie Culver


Spatial analysis of Honolulu motor vehicle crashes: I. Spatial patterns  

Microsoft Academic Search

This study describes spatial patterns in Honolulu motor vehicle accidents for 1990. A method for geo-coding accident locations is utilized with approximately 98% of the crash locations being identified. Spatial software tools are developed for describing the degree of spatial concentration. The spatial patterns of different types of accidents and accidents for every hour of the day, weekdays and weekends

Ned Levine; Karl E. Kim; Lawrence H. Nitz



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.



R-trees: a dynamic index structure for spatial searching  

Microsoft Academic Search

In order to handle spatial data efficiently, as required in computer aided design and geo-data applications, a database system needs an mdex mechanism that ti help it retrieve data items quickly accordmg to their spatial locations However, traditional mdexmg methods are not well suited to data oblects of non-zero size located m multidimensional spaces In this paper we describe a

Antonin Guttman



Spatially varying dynamical properties of turbid media probed with  

E-print Network

Spatially varying dynamical properties of turbid media probed with diffusing temporal light in turbid media and is accurately modeled by a correlation diffusion equation. We demonstrate ex of the spatially varying dynamical properties of turbid media. The biomedical applicability of this diffuse


Spatial light modulator microscopy.  


The use of spatial light modulators (SLMs) for two-photon laser microscopy is described. SLM phase modulation can be used to generate nearly any spatiotemporal pattern of light, enabling simultaneous illumination of any number of selected regions of interest. We take advantage of this flexibility to perform fast two-photon imaging or uncaging experiments on dendritic spines and neocortical neurons. By operating in the spatial Fourier plane, an SLM can effectively mimic any arbitrary optical transfer function and thus replace, in software, many of the functions provided by hardware in standard microscopes, such as focusing, magnification, and aberration correction. PMID:24298039

Nikolenko, Volodymyr; Peterka, Darcy S; Araya, Roberto; Woodruff, Alan; Yuste, Rafael



Site characterization: a spatial estimation approach  

SciTech Connect

In this report the application of spatial estimation techniques or kriging to groundwater aquifers and geological borehole data is considered. The adequacy of these techniques to reliably develop contour maps from various data sets is investigated. The estimator is developed theoretically in a simplified fashion using vector-matrix calculus. The practice of spatial estimation is discussed and the estimator is then applied to two groundwater aquifer systems and used also to investigate geological formations from borehole data. It is shown that the estimator can provide reasonable results when designed properly.

Candy, J.V.; Mao, N.



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] [ORNL; Forrest, Stephanie [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Groat, Michael [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque



Spatial Organization in Blind Children.  

ERIC Educational Resources Information Center

Reviews the development of spatial organization in children with blindness. Discusses the importance of motor exploration, tactual development, and spatial representation as critical factors in developing spatial and cognitive organizations of their surroundings. Suggests seven specific activities to improve spatial organization in blind children.…

Wheeler, Linda C.; And Others



Heredity Factors in Spatial Visualization.  

ERIC Educational Resources Information Center

Spatial visualization is not yet clearly understood. Some researchers have concluded that two factors or abilities are involved, spatial orientation and spatial visualization. Different definitions and different tests have been proposed for these two abilities. Several studies indicate that women generally perform more poorly on spatial tests than…

Vandenberg, S. G.


Virtual Reality Rehabilitation of Spatial Abilities after Brain Damage  

E-print Network

Virtual Reality Rehabilitation of Spatial Abilities after Brain Damage Sebastian T. KOENIGA physio- and occupational therapy sessions. To further promote generalization of gained abilities and to quantify functional improvements, this project aims at developing a virtual reality (VR) application

Hickman, Mark



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...


1 INTRODUCTION Spatial and spatio-temporal distributions of both  

E-print Network

using various methods (remote sensing, site sampling, etc.) leading to heterogeneous datasets resolutions. 2 PROBLEM FORMULATION AND CRITERIA FOR SOLUTIONS The general formulation of the spatial applications, should therefore satisfy several important demands: accuracy and predictive power, robustness

Mitasova, Helena


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.



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.



Spatially Resolved Luminescence Spectroscopy  

NASA Astrophysics Data System (ADS)

Spatially resolved luminescence spectroscopy is a useful tool for the study of semiconductors with inhomogeneities of their properties on submicrometer scale and semiconductor nanostructures. In this chapter, basic operation principles, instrumentation, and advantages and disadvantages of micro-photoluminescence (?-PL), confocal microscopy, scanning near-field optical microscopy (SNOM), and cathodoluminescence (CL) are discussed.

Tamulaitis, Gintautas


Spatial Terahertz Modulator  

NASA Astrophysics Data System (ADS)

Terahertz (THz) technology is a developing and promising candidate for biological imaging, security inspection and communications, due to the low photon energy, the high transparency and the broad band properties of the THz radiation. However, a major encountered bottleneck is lack of efficient devices to manipulate the THz wave, especially to modulate the THz wave front. A wave front modulator should allow the optical or electrical control of the spatial transmission (or reflection) of an input THz wave and hence the ability to encode the information in a wave front. Here we propose a spatial THz modulator (STM) to dynamically control the THz wave front with photo-generated carriers. A computer generated THz hologram is projected onto a silicon wafer by a conventional spatial light modulator (SLM). The corresponding photo-generated carrier spatial distribution will be induced, which forms an amplitude hologram to modulate the wave front of the input THz beam. Some special intensity patterns and vortex beams are generated by using this method. This all-optical controllable STM is structure free, high resolution and broadband. It is expected to be widely used in future THz imaging and communication systems.

Xie, Zhenwei; Wang, Xinke; Ye, Jiasheng; Feng, Shengfei; Sun, Wenfeng; Akalin, Tahsin; Zhang, Yan



Spatial Ability and Handedness.  

ERIC Educational Resources Information Center

The relationships among preferred handedness, family history of sinistrality, sex of subject, and spatial visualization were examined in college students. Males outperformed females at all levels of handedness when measured as a continuous variable. Extreme handedness was associated with poorest performance. Decreased hemispheric specialization…

Burnett, Sarah A.; And Others



Velocity Profile Spatial Profile  

E-print Network

by different colors. The black horizontal bar indicates the time window used for the ROC-analysis. (B *New York University, Center for Neural Science 3. ROC-ANALYSIS 5. RESULTS 4. TIME COURSE Visual0 0 0 Velocity Profile velocity time increment decrement no change Spatial Profile t t0 1 Averaged


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. PMID:23459794

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



Spatial management of data  

Microsoft Academic Search

Spatial data management is a technique for organizing and retrieving information by positioning it in a graphical data space (GDS). This graphical data space is viewed through a color raster-scan display which enables users to traverse the GDS surface or zoom into the image to obtain greater detail. In contrast to conventional database management systems, in which users access data

Christopher F. Herot



Spatial search by quantum walk  

NASA Astrophysics Data System (ADS)

Grover’s quantum search algorithm provides a way to speed up combinatorial search, but is not directly applicable to searching a physical database. Nevertheless, Aaronson and Ambainis showed that a database of N items laid out in d spatial dimensions can be searched in time of order N for d>2 , and in time of order Npoly(logN) for d=2 . We consider an alternative search algorithm based on a continuous-time quantum walk on a graph. The case of the complete graph gives the continuous-time search algorithm of Farhi and Gutmann, and other previously known results can be used to show that N speedup can also be achieved on the hypercube. We show that full N speedup can be achieved on a d -dimensional periodic lattice for d>4 . In d=4 , the quantum walk search algorithm takes time of order Npoly(logN) , and in d<4 , the algorithm does not provide substantial speedup.

Childs, Andrew M.; Goldstone, Jeffrey



Making a Place for Space: Spatial Thinking in Social Science  

PubMed Central

New technologies and multilevel data sets that include geographic identifiers have heightened sociologists’ interest in spatial analysis. I review several of the key concepts, measures, and methods that are brought into play in this work, and offer examples of their application in a variety of substantive fields. I argue that the most effective use of the new tools requires greater emphasis on spatial thinking. A device as simple as an illustrative map requires some understanding of how people respond to visual cues; models as complex as HLM with spatial lags require thoughtful measurement decisions and raise questions about what a spatial effect represents. PMID:24273374

Logan, John R.



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. PMID:24146799

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



The importance of scale for spatial-confounding bias and precision of spatial regression estimators  

PubMed Central

Residuals in regression models are often spatially correlated. Prominent examples include studies in environmental epidemiology to understand the chronic health effects of pollutants. I consider the effects of residual spatial structure on the bias and precision of regression coefficients, developing a simple framework in which to understand the key issues and derive informative analytic results. When unmeasured confounding introduces spatial structure into the residuals, regression models with spatial random effects and closely-related models such as kriging and penalized splines are biased, even when the residual variance components are known. Analytic and simulation results show how the bias depends on the spatial scales of the covariate and the residual: one can reduce bias by fitting a spatial model only when there is variation in the covariate at a scale smaller than the scale of the unmeasured confounding. I also discuss how the scales of the residual and the covariate affect efficiency and uncertainty estimation when the residuals are independent of the covariate. In an application on the association between black carbon particulate matter air pollution and birth weight, controlling for large-scale spatial variation appears to reduce bias from unmeasured confounders, while increasing uncertainty in the estimated pollution effect. PMID:21528104

Paciorek, Christopher J



Spatial pattern of diarrhea based on regional economic and environment by spatial autoregressive model  

NASA Astrophysics Data System (ADS)

The diarrhea case pattern information, especially for toddler, is very important. It is used to show the distribution of diarrhea in every region, relationship among that locations, and regional economic characteristic or environmental behavior. So, this research uses spatial pattern to perform them. This method includes: Moran's I, Spatial Autoregressive Models (SAR), and Local Indicator of Spatial Autocorrelation (LISA). It uses sample from 23 sub districts of Bekasi Regency, West Java, Indonesia. Diarrhea case, regional economic, and environmental behavior of households have a spatial relationship among sub district. SAR shows that the percentage of Regional Gross Domestic Product is significantly effect on diarrhea at ? = 10%. Therefore illiteracy and health center facilities are significant at ? = 5%. With LISA test, sub districts in southern Bekasi have high dependencies with Cikarang Selatan, Serang Baru, and Setu. This research also builds development application that is based on java and R to support data analysis.

Bekti, Rokhana Dwi; Nurhadiyanti, Gita; Irwansyah, Edy



[Spatial heterogeneity of land use intensity].  


To approach the spatial heterogeneity of human disturbance is of significance in researching the dynamics of land cover change, especially the characteristics of its directional structure. Jinjiang City is a "hot" region of land use change in Fujian Province, and the land has experienced intense human disturbance. This paper studied the spatial heterogeneity of land use intensity and human disturbance in this city in 1989 - 2001, with systematic grid sampling method and geostatistics in application. The results revealed that there was an obvious spatial heterogeneity of human disturbance in the study area, especially the directional structure of NE-SW caused by the traffic line from Qingyang-Anhai. Human disturbance was grown in the whole area, and the administrative centers served as the growth poles. Because of the associated influence of traffic lines and administrative centers, human disturbance was of a pole-axis structure. PMID:16836088

Wang, Guojie; Liao, Shangang



Spatial audio through a bone conduction interface.  


Headphones are the standard presentation device for radio communication in the military. Although bone conduction devices possess several advantages over headphones for some military applications, they are generally considered inappropriate for inclusion in a multi-channel system. The current study tested the feasibility of a multi-channel bone conduction system by measuring the localizability of spatialized auditory stimuli presented through a pair of bone conduction vibrators. Listeners localized a Gaussian noise stimulus spatialized with individualized head-related transfer functions (HRTFs). The sounds were presented from eight virtual locations on the horizontal plane (0, +/-45, +/-90, +/-135, and 180 degrees ) through either stereo headphones or a stereo bone conduction system. Localization performance was found to be nearly identical for both audio systems, indicating that bone conduction systems can be effectively used for displaying spatial information. PMID:17062501

MacDonald, Justin A; Henry, Paula P; Letowski, Tomasz R



Effective data mining: a data warehouse-backboned architecture  

Microsoft Academic Search

An effective Data Mining (DM) system for mining multiple-level knowledge from Data Warehouse . An adaptive hybrid view technique is introduced to manage storage space. DM and OLAP technologies are closely integrated. The mining and OLAP kernel includes generic analysis modules for performing a wide spectrum of applications. Active data mining is adopted to support knowledge-driven business processes. Continuously gathered

Khalil M. Ahmed; Nagwa M. El-Makky; Yousry Taha



Business Intelligence for Home Care Source Data and ETL Process  

E-print Network

Business Intelligence for Home Care Source Data and ETL Process OLAP Cube and BI Application Future Work and Conclusion Business Intelligence in the Home Care Sector Peter Poulsen Lars Schunk Lasse Care Sector 1 / 32 #12;Business Intelligence for Home Care Source Data and ETL Process OLAP Cube and BI

Kaiserslautern, Universität


Providing Probabilistically-Bounded Approximate Answers to Non-Holistic Aggregate  

E-print Network

Providing Probabilistically-Bounded Approximate Answers to Non-Holistic Aggregate Range Queries answers to non-holistic aggregate range queries in OLAP is presented in this paper. Such a framework allows us to efficiently support OLAP applications, as answering queries is the main bottleneck

Song, Il-Yeol


Misspecification in Linear Spatial Regression Models  

Microsoft Academic Search

Spatial effects are endemic in models based on spatially referenced data. The increased awareness of the relevance of spatial interactions, spatial externalities and networking effects among actors, evoked the area of spatial econometrics. Spatial econometrics focuses on the specification and estimation of regression models explicitly incorporating such spatial effects. The multidimensionality of spatial effects calls for misspecification tests and estimators

Raymond J. G. M. Florax; Peter Nijkamp



Children's spatial thinking: does talk about the spatial world matter?  


In this paper we examine the relations between parent spatial language input, children's own production of spatial language, and children's later spatial abilities. Using a longitudinal study design, we coded the use of spatial language (i.e. words describing the spatial features and properties of objects; e.g. big, tall, circle, curvy, edge) from child age 14 to 46 months in a diverse sample of 52 parent-child dyads interacting in their home settings. These same children were given three non-verbal spatial tasks, items from a Spatial Transformation task (Levine et al., 1999), the Block Design subtest from the WPPSI-III (Wechsler, 2002), and items on the Spatial Analogies subtest from Primary Test of Cognitive Skills (Huttenlocher & Levine, 1990) at 54 months of age. We find that parents vary widely in the amount of spatial language they use with their children during everyday interactions. This variability in spatial language input, in turn, predicts the amount of spatial language children produce, controlling for overall parent language input. Furthermore, children who produce more spatial language are more likely to perform better on spatial problem solving tasks at a later age. PMID:22010900

Pruden, Shannon M; Levine, Susan C; Huttenlocher, Janellen



Stable spatial solitons in semiconductor optical amplifiers  

NASA Astrophysics Data System (ADS)

A spatial soliton is a shape invariant self guided beam of light or a self induced waveguide. Spatial solitons appear as a result of the balance of diffraction and nonlinear focusing in a system. They have been observed in many different conservative media in the last couple of years. Solitons are ubiquitous, because of the probability of using their interactions in optical data processing, communications etc. Up to now due to the power required to generate the solitons, and the response times of the soliton supporting media, these special waves of nature could not penetrate the applications arena. Semiconductors, with their resonant nonlinearities, are thought to be ideal candidates for fast switching, low power spatial solitons. In this dissertation it is shown theoretically and experimentally that it is possible to observe stable spatial solitons in a periodically patterned semiconductor optical amplifier (PPSOA). The solitons have unique beam profiles that change only with system parameters, like pumping current, etc. Their coherent and incoherent interactions which could lead to all optical devices have been investigated experimentally and theoretically. The formation of filaments or modulational instability has been studied theoretically and yielded analytical formulae for evaluating the filament gain and the maximum spatial frequencies in PPSOA devices. Furthermore, discrete array amplifiers have been analyzed numerically for discrete solitons, and the prospect of using multi peak discrete solitons as laser amplifiers is discussed.

Ultanir, Erdem



Spatial modeling of cell signaling networks.  


The shape of a cell, the sizes of subcellular compartments, and the spatial distribution of molecules within the cytoplasm can all control how molecules interact to produce a cellular behavior. This chapter describes how these spatial features can be included in mechanistic mathematical models of cell signaling. The Virtual Cell computational modeling and simulation software is used to illustrate the considerations required to build a spatial model. An explanation of how to appropriately choose between physical formulations that implicitly or explicitly account for cell geometry and between deterministic versus stochastic formulations for molecular dynamics is provided, along with a discussion of their respective strengths and weaknesses. As a first step toward constructing a spatial model, the geometry needs to be specified and associated with the molecules, reactions, and membrane flux processes of the network. Initial conditions, diffusion coefficients, velocities, and boundary conditions complete the specifications required to define the mathematics of the model. The numerical methods used to solve reaction-diffusion problems both deterministically and stochastically are then described and some guidance is provided in how to set up and run simulations. A study of cAMP signaling in neurons ends the chapter, providing an example of the insights that can be gained in interpreting experimental results through the application of spatial modeling. PMID:22482950

Cowan, Ann E; Moraru, Ion I; Schaff, James C; Slepchenko, Boris M; Loew, Leslie M



Particle detector spatial resolution  


Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector.

Perez-Mendez, Victor (Berkeley, CA)



Particle detector spatial resolution  


Method and apparatus for producing separated columns of scintillation layer material, for use in detection of X-rays and high energy charged particles with improved spatial resolution is disclosed. A pattern of ridges or projections is formed on one surface of a substrate layer or in a thin polyimide layer, and the scintillation layer is grown at controlled temperature and growth rate on the ridge-containing material. The scintillation material preferentially forms cylinders or columns, separated by gaps conforming to the pattern of ridges, and these columns direct most of the light produced in the scintillation layer along individual columns for subsequent detection in a photodiode layer. The gaps may be filled with a light-absorbing material to further enhance the spatial resolution of the particle detector. 12 figs.

Perez-Mendez, V.



Describing migration spatial structure  

Microsoft Academic Search

.   The age structure of a population is a fundamental concept in demography and is generally depicted in the form of an age\\u000a pyramid. The spatial structure of an interregional system of origin-destination-specific migration streams is, however, a\\u000a notion lacking a widely accepted definition. We offer a definition in this article, one that draws on the log-linear specification\\u000a of the

Andrei Rogers; Frans Willekens; Jani Little; James Raymer



SpectralSpatial Preprocessing Using Multihypothesis Prediction for Noise-Robust  

E-print Network

accuracy of hyperspectral image classification. Specifically, multiple spatially collocated pixel vectors-sensing applications, being a theme common to environmental mapping, crop analysis, plant and mineral identi- fication

Fowler, James E.


MobiSpatial : open source for mobile spatial interaction  

Microsoft Academic Search

This paper describes our Mobile Spatial Interaction (MSI) prototype MobiSpatial, which benefits from location and orientation aware smartphones and existing open source spatial data initiatives to facilitate user interaction with the geospatial query process. We utilize today's ubiquitous mobile device as the central computing platform to calculate a mobile user's visibility shape at his\\/her current location. MobiSpatial uses this shape

Junjun Yin; James D. Carswell



Discussion on the choice of separated components in fMRI data analysis by spatial independent component analysis  

Microsoft Academic Search

By measuring the changes of magnetic resonance signals during a stimulation, the functional magnetic resonance imaging (fMRI) is able to localize the neural activation in the brain. In this report, we discuss the fMRI application of the spatial independent component analysis (spatial ICA), which maximizes statistical independence over spatial images. Included simulations show the possibility of the spatial ICA on

Huafu Chen; Dezhong Yao



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



Approximation techniques for spatial data  

Microsoft Academic Search

Spatial Database Management Systems (SDBMS), e.g., Geographical Information Systems, that manage spatial objects such as points, lines, and hyper-rectangles, often have very high query processing costs. Accurate selectivity estimation during query optimization therefore is crucially important for finding good query plans, especially when spatial joins are involved. Selectivity estimation has been studied for relational database systems, but to date has

Abhinandan Das; Johannes Gehrke; Mirek Riedewald



Carbon flux data spatialization using neural networks  

NASA Astrophysics Data System (ADS)

Artificial neural networks constitute a field in fast expansion that finds application in many fields, from properly scientific disciplines (physics, biology, chemistry, etc.) to typically humanistic disciplines (literature, language, social studies, etc.) In biology and ecology applications, the neural methods are able to represent in a very effective way the complexity of phenomena in examination and their non-linear behaviour. We present the results of a work where we tested the capability of neural networks to generalize the carbon flux data collected by flux towers to obtain NEE spatialization at regional and continental scale.

Papale, D.; Valentini, R.



"Some new spatial point process models for functional neuroimaging meta analysis"  

E-print Network

"Some new spatial point process models for functional neuroimaging meta analysis" Jian Kang Emory on some new spatial point process models with their applications to meta analysis of functional labels that classify each study, we con- struct a Bayesian spatial point process classifier based

Arnold, Jonathan


Enhancing hyperspectral spatial resolution using multispectral image fusion: A wavelet approach  

Microsoft Academic Search

High spectral and spatial resolution images have a significant impact in remote sensing applications. Because both spatial and spectral resolutions of spaceborne sensors are fixed by design and it is not possible to further increase the spatial or spectral resolution, techniques such as image fusion must be applied to achieve such goals. This dissertation introduces the concept of wavelet fusion

Amin Jazaeri



Application of multi-stable isotope (?13C, ?15N, ?34S, ?37Cl) assays to assess spatial separation of fish (longnose sucker Catostomus catostomus) in an area receiving complex effluents  

Microsoft Academic Search

Incorporation of stable isotope analysis (SIA) into routine environmental effects monitoring programs of receiving waters may enable determination of the spatial extent of biotic exposure and discrimination among sources of complex effluents. To evaluate this hypothesis, longnose sucker (Catostomus catostomus) were collected from four sites along the Athabasca River, Alberta (upstream reference site, two sites downstream of effluents from two

M. G. Dube; Glenn A. Benoy; Sandra Blenkinsopp; Jenny-Marie Ferone; Robert B. Brua; Leonard I. Wassenaar



Quadratic spatial solitons  

NASA Astrophysics Data System (ADS)

Quadratic spatial solitons, beams that propagate unchanged in shape and magnitude, are supported by second order optical nonlinearities and can occur in all wave mixing processes under appropriate conditions. They are multi-component, consisting of all the frequency components that are coupled by a second order nonlinear interaction near a phase-matching condition. They have been observed in a number of bulk crystalline media, in LiNbO 3 slab waveguides and in arrays of parallel, weakly coupled, LiNbO 3 channel waveguides. The properties of the solitons and their excitation will be reviewed. To cite this article: G.I. Stegeman, C. R. Physique 8 (2007).

Stegeman, George I.



: Intelligent, Interactive Investigaton of OLAP data cubes Sunita Sarawagi  

E-print Network

and numeric attributes like Sales and Revenue forming the measures or cells of the multidimensional cube Technology Indian Institute of Technology, Bombay Mumbai 400076, INDIA Phone: +91-22-576-7904, Fax: +91

Sarawagi, Sunita


Main-Memory & Near-Main-Memory OLAP Databases  

E-print Network

,200CompaqBC HydroPrinter 14,000CompaqSFUPC 45,000CompaqUBCPrinter 15,500DellBC HydroDisk 14,000DellSFUPC 25 Printer #12;11 Aggregation on a Cube Aggregation can be done very efficiently on the multidimensional-Campus Day Evening Distance Ed. Harbor Centre Location Dimension All Fall Spring Summer Regular Intersession

Li, Ze-Nian


Extending Complex AdHoc OLAP Theodore Johnson Damianos Chatziantoniou  

E-print Network

is easily optimized into efficient query plans. We show that nested aggregation queries can be evaluated queries. Many queries require complex aggregation, and many of these aggregates are non­ distributive efficiently by using a small extension to the EMF SQL query evaluation algorithm. A side effect

Chatziantoniou, Damianos


Bayesian semiparametric model with spatially-temporally varying coefficients selection  

PubMed Central

In spatio-temporal analysis, the effect of a covariate on the outcome usually varies across areas and time. The spatial configuration of the areas may potentially depend on not only the structured random intercept but also spatially varying coefficients of covariates. In addition, the normality assumption of the distribution of spatially varying coefficients could lead to potential biases of estimations. In this article, we propose a Bayesian semiparametric space-time model where the spatially-temporally varying coefficient is decomposed as fixed, spatially varying and temporally varying coefficients. The spatially varying coefficients of space-time covariates are modeled nonparametrically by using the area-specific Dirichlet process prior with weights transformed via a generalized transformation. Temporally varying coefficients of covariates are modeled through the dynamic model. Uncertainty of inclusion of the spatially-temporally varying coefficients is also taken into account by variable selection procedure through determining the probabilities of different effects for each covariate. The proposed semiparametric approach shows the improvement compared to the Bayesian spatial-temporal models with normality assumption on spatial random effects and the Bayesian model with the Dirichlet process prior on the random intercept. A simulation example is presented to evaluate the performance of the proposed approach with the competing models. An application to low birth weight data in South Carolina is used for an illustration. PMID:23526312

Cai, Bo; Lawson, Andrew B.; Hossain, Md. Monir; Choi, Jungsoon; Kirby, Russell S.; Liu, Jihong



Chunking in Spatial Memory  

PubMed Central

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 as a unit. Participants learned the locations of an array of objects around them in a room, then were blindfolded and underwent a succession of passive, whole-body rotations. After each rotation, participants pointed to remembered target locations. Targets were located more precisely relative to each other if they were (a) separated by smaller angular distances, (b) contained within the same regularly configured arrangement, or (c) corresponded to parts of a common object. A hypothesis is presented describing the roles played by egocentric and allocentric information within the spatial updating system. Results are interpreted in terms of an existing neural systems model, elaborating the model’s conceptualization of how parietal (egocentric) and medial temporal (allocentric) representations interact. PMID:20438258

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



Spatial cyclotron damping  

NASA Technical Reports Server (NTRS)

To examine spatial electron cyclotron damping in a uniform Vlasov plasma, it is noted that the plasma response to a steady-state transverse excitation consists of several terms (dielectric-pole, free-streaming, and branch-cut), but that the cyclotron-damped pole term is the dominant term for z l = c/w sub ce provided (w sub pe/w sub ce) squared (c/a) is much greater than 1. If the latter inequality does not hold, then the free-streaming and branch-cut terms persist well past z = c/w sub ce as w sub 1 approaches w sub ce, making experimental measurement of cyclotron damping essentially impossible. Considering only (w sub pe/w sub ce) squared (c/a) is much greater than 1, it is shown how collisional effects should be estimated and how a finite-width excitation usually has little effect on the cyclotron-damped part of the response. Criteria is established concerning collisional damping, measurable damping length sizes, and allowed uncertainty in the magnetic field Beta. Results of numerical calculations, showing the regions in the appropriate parameter spaces that meet these criteria, are presented. From these results, one can determine the feasibility of, or propose parameter values for, an experiment designed to measure spatial cyclotron damping. It is concluded that the electron temperature T sub e should be at least 1 ev., and preferably 10 ev. or higher, for a successful experiment.

Olson, C. L.



Join-Queries between Two Spatial Datasets Indexed by a Single R*Tree  

Microsoft Academic Search

\\u000a A spatial join, a common query in Spatial Databases and Geographical Information Systems (GIS), consists in testing every\\u000a possible pair of data elements belonging to two spatial datasets against a spatial predicate. This predicate might be “intersects”,\\u000a “contains”, “is enclosed by”, “distance”, “northwest”, “adjacent”, “meets”, etc. The large size of datasets that appears in\\u000a industrial and commercial modern applications (e.g.

Michael Vassilakopoulos; Antonio Corral; Nikitas N. Karanikolas



Application of laser ablation–inductively coupled plasma-mass spectrometry (LA–ICP–MS) to investigate trace metal spatial distributions in human tooth enamel and dentine growth layers and pulp  

Microsoft Academic Search

Human tooth enamel provides a nearly permanent and chronological record of an individual’s nutritional status and anthropogenic trace metal exposure during development; it might thus provide an excellent bio archive. We investigated the micro-spatial distribution of trace metals (Cu, Fe, Mg, Sr, Pb, and Zn) in 196×339 µm 2 raster pattern areas (6.6×10 4 µm 2) in a deciduous tooth using laser

Daniel Kang; Dulasiri Amarasiriwardena; Alan H. Goodman



Chemistry with spatial control using particles and streams().  


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



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. PMID:23145348

Kalinin, Yevgeniy V.; Murali, Adithya



Spatial search by quantum walk  

SciTech Connect

Grover's quantum search algorithm provides a way to speed up combinatorial search, but is not directly applicable to searching a physical database. Nevertheless, Aaronson and Ambainis showed that a database of N items laid out in d spatial dimensions can be searched in time of order {radical}(N) for d>2, and in time of order {radical}(N) poly(log N) for d=2. We consider an alternative search algorithm based on a continuous-time quantum walk on a graph. The case of the complete graph gives the continuous-time search algorithm of Farhi and Gutmann, and other previously known results can be used to show that {radical}(N) speedup can also be achieved on the hypercube. We show that full {radical}(N) speedup can be achieved on a d-dimensional periodic lattice for d>4. In d=4, the quantum walk search algorithm takes time of order {radical}(N) poly(log N), and in d<4, the algorithm does not provide substantial speedup.

Childs, Andrew M.; Goldstone, Jeffrey [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)



Mining Regional Knowledge in Spatial Datasets Wei Ding Christoph. F. Eick  

E-print Network

in the field of spatial data min- ing and its applications in geosciences and planetary sci- ences. Spatial to sys- tematically discover regional patterns and apply it to real- world applications in planetary-based, representative- based, grid-based, and agglomerative clustering algorithms to find such regional patterns

Ding, Wei


Automated Spatial Data Generalisation in Support of Diasters Response  

Microsoft Academic Search

Strain for maintaining up-to-date maps at a range of scales for intelligence spatial decision mapping are ever growing. Many e-government agencies and private organizations projects require highly developed applications software tools in responding to disaster events using location-based services. This underpins reliance on accurate, economical and viable digital spatial information products. Albeit the fact that automated generalisation systems meet these

Sharon Kazemi; Samsung Lim



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.



New advances in spatial network modelling: Towards evolutionary algorithms  

Microsoft Academic Search

This paper discusses analytical advances in evolutionary methods with a view towards their possible applications in the space-economy.For this purpose, we present a brief overview and illustration of models actually available in the spatial sciences which attempt to map the complex patterns of spatial\\/social networks. Particular attention is given to new emerging tools, such as neural networks (NNs) and evolutionary

Aura Reggiani; Peter Nijkamp; Enrico Sabella



Recherche d'Emploi, Contraintes Spatiales et Durée de Chômage  

Microsoft Academic Search

Un modèle de recherche d'emploi est proposé afin d'expliquer les déterminants du choix de l'horizon spatial de la recherche et l'effet de ce choix sur la durée du chômage. Cette question se trouve au croisement de deux champs d'application de la microéconomie : la microéconomie de l'emploi d'un coté, et la microéconomie spatiale de l'autre. Les propriétés de statique comparative

Khaled Bouabdallah; Sandra Cavaco; Jean-Yves Lesueur



Modality fusion for graphic design applications  

Microsoft Academic Search

Users must enter a complex mix of spatial and abstract information when operating a graphic design application. Speech \\/ language provides a fluid and natural method for specifying abstract information while a spatial input device is often most intuitive for the entry of spatial information. Thus, the combined speech \\/ gesture interface is ideally suited to this application domain. While

André D. Milota




PubMed Central

Unilateral spatial neglect is a common neurological syndrome following predominantly right hemisphere injuries to ventral fronto-parietal cortex. We propose that neglect reflects deficits in the coding of saliency, control of spatial attention, and representation within an egocentric frame of reference, in conjunction with non-spatial deficits of reorienting, target detection, and arousal/vigilance. In contrast to theories that link spatial neglect to structural damage of specific brain regions, we argue that neglect is better explained by the physiological dysfunction of distributed cortical networks. The ventral lesions in right parietal, temporal, and frontal cortex that cause neglect directly impair non-spatial functions and hypoactivate the right hemisphere, inducing abnormalities in task-evoked activity and functional connectivity of a dorsal frontal-parietal network that controls spatial attention. The anatomy and right hemisphere dominance of neglect follows from the anatomy and laterality of the ventral regions that interact with the dorsal attention network. PMID:21692662

Corbetta, Maurizio; Shulman, Gordon L.



On the analysis of spatial binary images.  


This paper deals with the analysis of spatial images taken from microscopically heterogeneous but macroscopically homogeneous microstructures. A new method is presented, which is strictly based on integral-geometric formulae such as Crofton's intersection formulae and Hadwiger's recursive definition of the Euler number. By means of this approach the quermassdensities can be expressed as the inner products of two vectors where the first vector carries the 'integrated local knowledge' about the microstructure and the second vector depends on the lateral resolution of the image as well as the quadrature rules used in the discretization of the integral-geometric formulae. As an example of application we consider the analysis of spatial microtomographic images obtained from natural sandstones. PMID:11555148

Lang, C; Ohser, J; Hilfer, R



Spatial propagation of protein polymerization.  


We consider the spatial dependence of filamentous protein self-assembly. Through studying the cases where the spreading of aggregated material is dominated either by diffusion or by growth, we derive analytical results for the spatial evolution of filamentous protein aggregation, which we validate against Monte Carlo simulations. Moreover, we compare the predictions of our theory with experimental measurements of two systems for which we identify the propagation as either growth or diffusion controlled. Our results connect the macroscopic observables that characterize the spatial propagation of protein self-assembly with the underlying microscopic processes and provide physical limits on spatial propagation and prionlike behavior associated with protein aggregation. PMID:24655282

Cohen, S I A; Rajah, L; Yoon, C H; Buell, A K; White, D A; Sperling, R A; Vendruscolo, M; Terentjev, E M; Dobson, C M; Weitz, D A; Knowles, T P J



Tomography of Spatial Mode Detectors  

E-print Network

Transformation and detection of photons in higher-order spatial modes usually requires complicated holographic techniques. Detectors based on spatial holograms suffer from non-idealities and should be carefully calibrated. We report a novel method for analyzing the quality of projective measurements in spatial mode basis inspired by quantum detector tomography. It allows us to calibrate the detector response using only gaussian beams. We experimentally investigate the inherent inaccuracy of the existing methods of mode transformation and provide a full statistical reconstruction of the POVM (positive operator valued measure) elements for holographic spatial mode detectors.

Bobrov, Ivan; Markov, Anton; Straupe, Stanislav; Kulik, Sergey



Spatial associative classification: propositional vs structural approach  

Microsoft Academic Search

Spatial associative classification takes advantage of employing association rules for spatial classification purposes. In this work, we investigate spatial associative classification in multi-relational data mining setting to deal with spatial objects having different properties, which are modeled by as many data tables (relations) as the number of spatial object types (layers). Spatial classification is based on two alternative approaches: a

Michelangelo Ceci; Annalisa Appice



A genetic algorithm for searching spatial configurations  

Microsoft Academic Search

Searching spatial configurations is a particular case of maximal constraint satisfaction prob- lems, where constraints expressed by spatial and non-spatial properties guide the search process. In the spatial domain, binary spatial relations are typically used for specifying constraints while searching spatial configurations. Searching configurations is particularly intractable when con- figurations are derived from a combination of objects, which involves a

M. Andrea Rodríguez; Mary Carmen Jarur



Spatial learning Hampton Court maze (London) Spatial learning: Small (1899)  

E-print Network

, 1948): ·Latent learning (incentive or motivational shift reveals learning) ·Vicarious trial and error......Submerged platform, different locations #12;Evidence for locale learning: Results Morris, 1981, Learn Motiv #12Spatial learning Hampton Court maze (London) #12;Goal Start Spatial learning: Small (1899) #12

Cooper, Brenton G.


Quadratic spatial soliton interactions  

NASA Astrophysics Data System (ADS)

Quadratic spatial soliton interactions were investigated in this Dissertation. The first part deals with characterizing the principal features of multi-soliton generation and soliton self-reflection. The second deals with two beam processes leading to soliton interactions and collisions. These subjects were investigated both theoretically and experimentally. The experiments were performed by using potassium niobate (KNBO 3) and periodically poled potassium titanyl phosphate (KTP) crystals. These particular crystals were desirable for these experiments because of their large nonlinear coefficients and, more importantly, because the experiments could be performed under non-critical-phase-matching (NCPM) conditions. The single soliton generation measurements, performed on KNBO3 by launching the fundamental component only, showed a broad angular acceptance bandwidth which was important for the soliton collisions performed later. Furthermore, at high input intensities multi-soliton generation was observed for the first time. The influence on the multi-soliton patterns generated of the input intensity and beam symmetry was investigated. The combined experimental and theoretical efforts indicated that spatial and temporal noise on the input laser beam induced multi-soliton patterns. Another research direction pursued was intensity dependent soliton routing by using of a specially engineered quadratically nonlinear interface within a periodically poled KTP sample. This was the first time demonstration of the self-reflection phenomenon in a system with a quadratic nonlinearity. The feature investigated is believed to have a great potential for soliton routing and manipulation by engineered structures. A detailed investigation was conducted on two soliton interaction and collision processes. Birth of an additional soliton resulting from a two soliton collision was observed and characterized for the special case of a non-planar geometry. A small amount of spiraling, up to 30 degrees rotation, was measured in the experiments performed. The parameters relevant for characterizing soliton collision processes were also studied in detail. Measurements were performed for various collision angles (from 0.2 to 4 degrees), phase mismatch, relative phase between the solitons and the distance to the collision point within the sample (which affects soliton formation). Both the individual and combined effects of these collision variables were investigated. Based on the research conducted, several all-optical switching scenarios were proposed.

Jankovic, Ladislav


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



One spatial map or many? Spatial coding of connected environments.  


We investigated how humans encode large-scale spatial environments using a virtual taxi game. We hypothesized that if 2 connected neighborhoods are explored jointly, people will form a single integrated spatial representation of the town. However, if the neighborhoods are first learned separately and later observed to be connected, people will form separate spatial representations; this should incur an accuracy cost when inferring directions from one neighborhood to the other. Interestingly, our data instead suggest that people have a very strong tendency to form local representations, regardless of whether the neighborhoods were learned together or separately. Only when all visible distinctions between neighborhoods were removed did people behave as if they formed one integrated spatial representation. These data are broadly consistent with evidence from rodent hippocampal place cell recordings in connected boxes, and with hierarchical models of spatial coding. PMID:24364723

Han, Xue; Becker, Suzanna



Spatial interference among moving targets  

Microsoft Academic Search

Peripheral vision for static form is limited both by reduced spatial acuity and by interference among adjacent features (‘crowding’). However, the visibility of acuity-corrected image motion is relatively constant across the visual field. We measured whether spatial interference among nearby moving elements is similarly invariant of retinal eccentricity and assessed if motion integration could account for any observed sensitivity loss.

Peter J. Bex; Steven C. Dakin



Gibbs ringing artifact, spatial correlation, and spatial resolution in MRI  

NASA Astrophysics Data System (ADS)

Gibbs ringing is an inevitable artifact in MR Fourier Transform (FT) imaging caused by truncating k-space data via a rectangular window. A common practice is to multiply k-space data with a filter function prior to FT reconstruction for softening the amount of ringing and accepting the concomitant blur. Although by properly choosing the filter functions, the apodization approach is effective in removing the overshoot and ringing, it is at the price of both spatial correlation and spatial resolution of pixel intensities in the reconstructed image. Our study reported in this paper shows that the truncation and apodization introduce/change the spatial correlation and the spatial resolution of pixel intensities in FT imaging. We develop a 4-step procedure progressively prove the spatially asymptotic independence of pixel intensities and introduce a delta-train method to derive the spatial resolution in the image, for both the basic and the filtered FT imaging. The methods are intuitive without any assumption and approximation. Different filter functions have been investigated. We also discuss the relationship between the spatial resolution and pixel size and correct some misconceptions on these issues.

Lei, Tianhu



Manakov spatial solitons  

NASA Astrophysics Data System (ADS)

The Manakov soliton is a two-component soliton that was first considered by Manakov in the early 1970s.1 Based on the work of Zakharov and Shabat,2 Manakov found that the coupled nonlinear Schrodinger (CNSE) equations with special choice of the coefficients in front of nonlinear terms can be solved exactly. This system is integrable and solitons have therefore a number of special properties which might be useful in practice. In particular, for same total power, the soliton of a single nonlinear Schrodinger equation and the Manakov soliton behave similarly. There are certain conditions for the integrability of the CNSE. Namely, for the coupled set of equations with cubic nonlinearity, the ratio between the self-phase modulation (SPM) to the cross-phase modulation coefficients has to be equal to unity, and the SPM coefficients need to be equal for the two polarizations. Moreover, the energy exchange terms or four-wave mixing (FWM) terms must be zero. Physically, the Manakov soliton is a mutually trapped state of two orthogonally polarized beams where each component of the soliton experiences exactly the same index potential which is proportional to the total intensity of the beam. There are no crystal symmetries that a priori lead to a SPM/XPM ratio of unity. Thus, the Manakov soliton has not been observed experimentally prior to the work we reported.3 Based on our previous work, we found that in AlGaAs, for photon energies just below half the band gap, the conditions for integrability can be satisfied. This led to the first experimental observation of spatial Manakov solitons.

Kang, J. U.; Stegeman, G. I.; Aitchison, J. S.; Akhmediev, N.



Directed spatial organization of zinc oxide nanorods.  

SciTech Connect

The ability to precisely place nanomaterials at predetermined locations is necessary for realizing applications using these new materials. Using an organic template, we demonstrate directed growth of zinc oxide (ZnO) nanorods on silver films from aqueous solution. Spatial organization of ZnO nanorods in prescribed arbitrary patterns was achieved, with unprecedented control in selectivity, crystal orientation, and nucleation density. Surprisingly, we found that caboxylate endgroups of {omega}-alkanethiol molecules strongly inhibit ZnO nucleation. The mechanism for this observed selectivity is discussed.

Simmons, Neil C.; Liu, Jun; Voigt, James A.; Hsu, Julia W. P.; Tian, Zhengrong Ryan; Matzke, Carolyn M.



Marine spatial planning in practice  

NASA Astrophysics Data System (ADS)

Multiple competing uses of continental-shelf environments have led to a proliferation of marine spatial planning initiatives, together with expert guidance on marine spatial planning. This study provides an empirical review of marine spatial plans, their attributes, and the extent to which the expert guidance is actually being followed. We performed a structured review of 16 existing marine spatial plans and created an idealized marine spatial plan from the steps included in recent expert papers. A cluster analysis of the yes/no answers to 28 questions was used to ordinate the 16 marine spatial plans and to compare them with the idealized plan. All the plans that have been implemented have a high-level government mandate and the authority to implement spatial planning vested in existing institutions. Almost all the plans used data with clear criteria for data inclusion. Stakeholders were included in almost all the plans; they did not participate in all stages of the planning process but their roles were generally clearly defined. Decision-support tools were applied inconsistently across plans and were seldom used dynamically over time. Most spatial planning processes did not select specific outcomes, such as preferred use scenarios. Success is defined inconsistently across plans; in half the cases there are no metrics of success with reference benchmarks. Although monitoring is included in the majority of plans, only in some cases do monitoring results feed back into management decisions. The process of marine spatial planning had advanced in that some of the more recent plans were developed more quickly and contain more desirable attributes than earlier plans. Even so, existing marine spatial plans are heterogeneous—there are essential ingredients, but no single recipe for success.

Collie, Jeremy S.; (Vic) Adamowicz, W. L.; Beck, Michael W.; Craig, Bethany; Essington, Timothy E.; Fluharty, David; Rice, Jake; Sanchirico, James N.



Non-equilibrium spatial dynamics of ecosystems.  


Ecological systems show tremendous variability across temporal and spatial scales. It is this variability that ecologists try to predict and that managers attempt to harness in order to mitigate risk. However, the foundations of ecological science and its mainstream agenda focus on equilibrium dynamics to describe the balance of nature. Despite a rich body of literature on non-equilibrium ecological dynamics, we lack a well-developed set of predictions that can relate the spatiotemporal heterogeneity of natural systems to their underlying ecological processes. We argue that ecology needs to expand its current toolbox for the study of non-equilibrium ecosystems in order to both understand and manage their spatiotemporal variability. We review current approaches and outstanding questions related to the study of spatial dynamics and its application to natural ecosystems, including the design of reserves networks. We close by emphasizing the importance of ecosystem function as a key component of a non-equilibrium ecological theory, and of spatial synchrony as a central phenomenon for its inference in natural systems. PMID:24984261

Guichard, Frederic; Gouhier, Tarik C



Structural Interactions in Spatial Panels  

E-print Network

speci…ed directional class such as north/ south. Standard spatial autocorrelation sta- tistics compare the spatial weights to the covariance relationship at pairs of locations. Spatial autocorrelation that is more positive than expected from random... available, the MPC has met once a month to decide on the base rate for the next month.10 Over most of this period, the MPC has had 9 members at any time: the Governor (of the Bank of England), 4 inter- nal members (senior sta¤ at the Bank of England) and 4...

Bhattacharjee, Arnab; Holly, Sean


Routing Algorithm Exploits Spatial Relations  

NASA Technical Reports Server (NTRS)

A recently developed routing algorithm for broadcasting in an ad hoc wireless communication network takes account of, and exploits, the spatial relationships among the locations of nodes, in addition to transmission power levels and distances between the nodes. In contrast, most prior algorithms for discovering routes through ad hoc networks rely heavily on transmission power levels and utilize limited graph-topology techniques that do not involve consideration of the aforesaid spatial relationships. The present algorithm extracts the relevant spatial-relationship information by use of a construct denoted the relative-neighborhood graph (RNG).

Okino, Clayton; Jennings, Esther



Spatial computation with gamma oscillations  

PubMed Central

Gamma oscillations in cortex have been extensively studied with relation to behavior in both humans and animal models; however, their computational role in the processing of behaviorally relevant signals is still not clear. One oft-overlooked characteristic of gamma oscillations is their spatial distribution over the cortical space and the computational consequences of such an organization. Here, we advance the proposal that the spatial organization of gamma oscillations is of major importance for their function. The interaction of specific spatial distributions of oscillations with the functional topography of cortex enables select amplification of neuronal signals, which supports perceptual and cognitive processing.

Engelhard, Ben; Vaadia, Eilon



ELSDE: A lightweight spatial data engine for mobile GIS  

NASA Astrophysics Data System (ADS)

Mobile GIS, a novel intercross research field integrating modern mobile computing techniques with geographic information science, has attracted more and more researchers in developing and deploying new techniques in mobile GIS. Efficiently exploiting the limited resources of mobile device, treating and manipulating geographic data using a uniform data model, and guaranteeing the dataset quality from field data collecting, require an appropriate mobile GIS architecture and an efficient underlying spatial data engine support. In this paper, we discuss the popular architectures of mobile GIS and present our approach: Embedded Lightweight Spatial Data Engine, named ELSDE. With efficient integration of embedded RDBMS, spatial index framework, binary topological predicates and the OpenGIS simple feature data model, ELSDE can provide a robust underlying spatial database like support for various higher-level mobile GIS applications.

He, Jun; Wang, Qing; Li, Zigang; Tai, Yingying



Adaptive proxy map server for efficient vector spatial data rendering  

NASA Astrophysics Data System (ADS)

The rapid transmission of vector map data over the Internet is becoming a bottleneck of spatial data delivery and visualization in web-based environment because of increasing data amount and limited network bandwidth. In order to improve both the transmission and rendering performances of vector spatial data over the Internet, we propose a proxy map server enabling parallel vector data fetching as well as caching to improve the performance of web-based map servers in a dynamic environment. Proxy map server is placed seamlessly anywhere between the client and the final services, intercepting users' requests. It employs an efficient parallelization technique based on spatial proximity and data density in case distributed replica exists for the same spatial data. The effectiveness of the proposed technique is proved at the end of the article by the application of creating map images enriched with earthquake seismic data records.

Sayar, Ahmet



Femtosecond spatial pulse shaping at the focal plane.  


Spatial shaping of ultrashort laser beams at the focal plane is theoretically analyzed. The description of the pulse is performed by its expansion in terms of Laguerre-Gaussian orthonormal modes. This procedure gives both a comprehensive interpretation of the propagation dynamics and the required signal to encode onto a spatial light modulator for spatial shaping, without using iterative algorithms. As an example, pulses with top-hat and annular spatial profiles are designed and their dynamics analyzed. The interference of top-hat pulses is also investigated finding potential applications in high precision pump-probe experiments (without using delay lines) and for the creation of subwavelength ablation patterns. In addition, a novel class of ultrashort pulses possessing non-stationary orbital angular momentum is also proposed. These exotic pulses provide additional degrees of freedom that open up new perspectives in fields such as laser-matter interaction and micro-machining. PMID:24150344

Martínez-Matos, Ó; Vaveliuk, P; Izquierdo, J G; Loriot, V



A spatial operator algebra for manipulator modeling and control  

NASA Technical Reports Server (NTRS)

A powerful new spatial operator algebra for modeling, control, and trajectory design of manipulators is discussed along with its implementation in the Ada programming language. Applications of this algebra to robotics include an operator representation of the manipulator Jacobian matrix; the robot dynamical equations formulated in terms of the spatial algebra, showing the complete equivalence between the recursive Newton-Euler formulations to robot dynamics; the operator factorization and inversion of the manipulator mass matrix which immediately results in O(N) recursive forward dynamics algorithms; the joint accelerations of a manipulator due to a tip contact force; the recursive computation of the equivalent mass matrix as seen at the tip of a manipulator; and recursive forward dynamics of a closed chain system. Finally, additional applications and current research involving the use of the spatial operator algebra are discussed in general terms.

Rodriguez, G.; Kreutz, K.; Milman, M.



Spatial Database Systems Tutorial Notes  

E-print Network

with extent city river cable highway forest lake city #12;Ralf Hartmut Güting, Tutorial Spatial Database ownership · "environments" of points Voronoi diagram · highways, streets · railways, public transport

Güting, Ralf Hartmut


Characterization Of Spatial Heterogeneity and Structure at Landscape Scale  

NASA Astrophysics Data System (ADS)

The monitoring of land surface dynamic processes at global scale, such as primary production, carbon and water fluxes, requires high temporal frequency remote sensing observations. Because of technological constraints, the sensors are characterized by coarse spatial resolution, i.e. a resolution from few hundred meters (MERIS/ENVISAT, MODIS/TERRA) up to one or few kilometres (VEGETATION/SPOT, SEVIRI/MSG). However, the scenes observed at this range of scales, present spatial heterogeneity which may have a great influence on land surface characteristic estimation from remotely sensed data. Therefore the characterisation of spatial heterogeneity is an important concern to scale non linear land surface processes. The aim of this study is to discuss a geostatistical approach based on two complementary tools to characterize spatial structure of remote sensing data at the landscape scale. The high spatial resolution NDVI (vegetation index) of SPOT/HRV images (20m resolution) is used to characterize the ground spatial structure of different landscapes. These NDVI images are then aggregated in order to describe the evolution of their structure with the spatial resolution. A classical method consists in describing the image spatial heterogeneity by a geostatistic tool: the variogram. The interest of the variogram is that it jointly allows to model the spatial distribution of a scene as well as to quantify the spatial heterogeneity as a function of the spatial resolution. A typology of spatial heterogeneity is derived from the variogram model parameters computed over several types of landscapes. To account for the availability of multiple wavebands, a multivariate description of the spatial heterogeneity could also be proposed. A first limit of the variogram approach is the assumption of spatial stationarity, necessary for modelling the variogram. Spatial stationarity can be checked by: Dividing the image into local windows and adjusting the corresponding variogram model parameters for a range of window size. Computing the variogram on increasing size of the same scene. A second limit of the variogram approach is that different models of spatial random fields can share the same variogram function. This is for example the case of the Gaussian random field with an exponential variogram and the mosaic model with Poisson random polyhedra. We show that these two models and their linear mixture are undistinguishable if the histogram and the variogram are the only tools used for characterizing the heterogeneity. In this work we propose to use the first order variogram to discriminate between these two models. Moreover, we show that it is possible to model a wide range of landscapes as a mixture of these models and to estimate their parameters and the proportion of the mixture. This new way of characterization of landscape spatial structure and heterogeneity is discussed with possible application to land surface characteristic estimation from coarse resolution observations. Key Words: remote sensing, spatial heterogeneity, landscape, scaling, spatial resolution, variogram, spatial random field simulation, non linear process

Garrigues, S.; Allard, D.; Baret, F.


Complex spatial\\/temporal CFAR  

Microsoft Academic Search

The conventional cell averaging constant false alarm rate (CFAR) criterion and its variations work well only in strictly spatially stationary environments. In non-homogeneous environments, clutter map (scan-by-scan) processing is deployed. The performance of this method degrades in the presence of slow targets. In this paper, a hybrid procedure for CFAR is proposed, which combines the advantages of both spatial and

Z. Ebrahimian