Fitting spatial models in the R package: hglm

We present a new version of the hglm package for fittinghierarchical generalized linear models (HGLM) with spatially correlated random effects. A CAR family for conditional autoregressive random effects was implemented. Eigen decomposition of the matrix describing the spatial structure (e.g. the neighborhood matrix) was used to transform the CAR random effectsinto an independent, but heteroscedastic, gaussian random effect. A linear predictor is fitted for the random effect variance to estimate the parameters in the CAR model.This gives a computationally efficient algorithm for moderately sized problems (e.g. n<5000).

Spatial Analysis of Colby College Trails: Perkins Arboretum and Runnals Hill

I created an updated map of trails at Colby College using global positioning system data that were then edited in ArcGIS. The map background, obtained from the Maine Office of GIS, was created from digital orthophotographs produced from aerial photos collected over southwest Maine in Spring 2003. Trail difficulty was determined by creating a slope layer and taking other factors into consideration such as ground surface and path width. The map will eventually be available online, enabling interactive selection of trails where users can access additional trail information.

Volunteered Geographic Information For Water Management: A Prototype Architecture

Driven by Web 2.0 technology and the almost ubiquitous presence of mobile devices, Volunteered Geographic Information (VGI) is knowing an unprecedented growth. These notable technological advancements have opened fruitful perspectives also in the field of water management and protection, raising the demand for a reconsideration of policies which also takes into account the emerging trend of VGI. This research investigates the opportunity of leveraging such technology to involve citizens equipped with common mobile devices (e.g. tablets and smartphones) in a campaign of report of water-related phenomena. The work is carried out in collaboration with ADBPO - Autorità di bacino del fiume Po (Po river basin Authority), i.e. the entity responsible for the environmental planning and protection of the basin of river Po. This is the longest Italian river, spreading over eight among the twenty Italian Regions and characterized by complex environmental issues. To enrich ADBPO official database with user-generated contents, a FOSS (Free and Open Source Software) architecture was designed which allows not only user field-data collection, but also data Web publication through standard protocols. Open Data Kit suite allows users to collect georeferenced multimedia information using mobile devices equipped with location sensors (e.g. the GPS). Users can report a number of environmental emergencies, problems or simple points of interest related to the Po river basin, taking pictures of them and providing other contextual information. Field-registered data is sent to a server and stored into a PostgreSQL database with PostGIS spatial extension. GeoServer provides then data dissemination on the Web, while specific OpenLayers-based viewers were built to optimize data access on both desktop computers and mobile devices. Besides proving the suitability of FOSS in the frame of VGI, the system represents a successful prototype for the exploitation of user local, real-time information aimed at managing and protecting water resources.

Using Neo4J geospatial data storage and integration

Online geographic-databases have been growing increasingly as they have become a crucial source of information for both social networks and safety-critical systems. Since the quality of such applications is largely related to the richness and completeness of their data, it becomes imperative to develop adaptable and persistent storage systems, able to make use of several sources of information as well as enabling the fastest possible response from them. This work will create a shared and extensible geographic model, able to retrieve and store information from the major spatial sources available. A geographic-based system also has very high requirements in terms of scalability, computational power and domain complexity, causing several difficulties for a traditional relational database as the number of results increases. NoSQL systems provide valuable advantages for this scenario, in particular graph databases which are capable of modeling vast amounts of inter-connected data while providing a very substantial increase of performance for several spatial requests, such as finding shortestpath routes and performing relationship lookups with high concurrency. In this work, we will analyze the current state of geographic information systems and develop a unified geographic model, named GeoPlace Explorer (GE). GE is able to import and store spatial data from several online sources at a symbolic level in both a relational and a graph databases, where several stress tests were performed in order to find the advantages and disadvantages of each database paradigm.

Increase in Hippocampal Theta Oscillations during Spatial Decision Making

The processing of spatial and mnemonic information is believed to depend on hippocampal theta oscillations (5–12 Hz). However, in rats both the power and the frequency of the theta rhythm are modulated by locomotor activity, which is a major confounding factor when estimating its cognitive correlates. Previous studies have suggested that hippocampal theta oscillations support decision-making processes. In this study, we investigated to what extent spatial decision making modulates hippocampal theta oscillations when controlling for variations in locomotion speed. We recorded local field potentials from the CA1 region of rats while animals had to choose one arm to enter for reward (goal) in a four-arm radial maze. We observed prominent theta oscillations during the decision-making period of the task, which occurred in the center of the maze before animals deliberately ran through an arm toward goal location. In speed-controlled analyses, theta power and frequency were higher during the decision period when compared to either an intertrial delay period (also at the maze center), or to the period of running toward goal location. In addition, theta activity was higher during decision periods preceding correct choices than during decision periods preceding incorrect choices. Altogether, our data support a cognitive function for the hippocampal theta rhythm in spatial decision making

Transfer function-noise modeling and spatial interpolation to evaluate the risk of extreme (shallow) water-table levels in the Brazilian Cerrados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Distribution of paracoccidioidomycosis: determination of ecologic correlates through spatial analyses

Paracoccidioidomycosis (PCM) is endemic in Latin America and in countries like Brazil it carries a high mortality rate. The fungus' habitat has not been precisely determined. The present study aims to identify ecologic correlates based on PCM distribution in a hyper-endemic area in southeastern Brazil. The Geographic Information System (GIS) and spatial statistics were used to associate environmental attributes, human population density and, PCM distribution. By means of the Pearson r correlation coefficient, the highest statistically significant associations with prevalence density were the percent area (by county) of: basaltic rocks (r = 0.63; P < 0.0001), Podzolic soils (r = - 0.48; P < 0.001), Latosol soils (r = 0.40; P < 0.01), mean annual precipitation between 1500 and 1600 mm (r = 0.46; P < 0.001) and, mean precipitation during the wet season between 940 and 1040 mm (r = - 0.44; P < 0.01). Soil texture and precipitation analyzed together reached r = 0.61 (P < 0.000002) for fine-textured soils with annual precipitation above 1400 mm. Environmental correlates indicate that moisture availability plays an important role in PCM distribution.

Spatial distribution of trachoma cases in the City of Bauru, State of São Paulo, Brazil, detected in 2006: defining key areas for improvement of health resources

Introduction: The objective of this study was to analyze the spatial behavior of the occurrence of trachoma cases detected in the City of Bauru, State of São Paulo, Brazil, in 2006 in order to use the information collected to set priority areas for optimization of health resources. Methods: the trachoma cases identified in 2006 were georeferenced. The data evaluated were: schools where the trachoma cases studied, data from the 2000 Census, census tract, type of housing, water supply conditions, distribution of income and levels of education of household heads. In the Google Earth® software and TerraView® were made descriptive spatial analysis and estimates of the Kernel. Each area was studied by interpolation of the density surfaces exposing events to facilitate to recognize the clusters. Results: of the 66 cases detected, only one (1.5%) was not a resident of the city's outskirts. A positive association was detected of trachoma cases and the percentage of heads of household with income below three minimum wages and schooling under eight years of education. Conclusions: The recognition of the spatial distribution of trachoma cases coincided with the areas of greatest social inequality in Bauru City. The micro-areas identified are those that should be prioritized in the rationalization of health resources. There is the possibility of using the trachoma cases detected as an indicator of performance of micro priority health programs.

Spatial Distribution of Seropositive Dogs to Leptospira spp. and Evaluation of Leptospirosis Risk Factors Using a Decision Tree

Background: Leptospirosis is an important zoonotic disease associated with poor areas of urban settings of developing countries and early diagnosis and prompt treatment may prevent disease. Although rodents are reportedly considered the main reservoirs of leptospirosis, dogs may develop the disease, may become asymptomatic carriers and may be used as sentinels for disease epidemiology. The use of Geographical Information Systems (GIS) combined with spatial analysis techniques allows the mapping of the disease and the identification and assessment of health risk factors. Besides the use of GIS and spatial analysis, the technique of data mining, decision tree, can provide a great potential to find a pattern in the behavior of the variables that determine the occurrence of leptospirosis. The objective of the present study was to apply Geographical Information Systems and data prospection (decision tree) to evaluate the risk factors for canine leptospirosis in an area of Curitiba, PR.Materials, Methods & Results: The present study was performed on the Vila Pantanal, a urban poor community in the city of Curitiba. A total of 287 dog blood samples were randomly obtained house-by-house in a two-day sampling on January 2010. In addition, a questionnaire was applied to owners at the time of sampling. Geographical coordinates related to each household of tested dog were obtained using a Global Positioning System (GPS) for mapping the spatial distribution of reagent and non-reagent dogs to leptospirosis. For the decision tree, risk factors included results of microagglutination test (MAT) from the serum of dogs, previous disease on the household, contact with rats or other dogs, dog breed, outdoors access, feeding, trash around house or backyard, open sewer proximity and flooding. A total of 189 samples (about 2/3 of overall samples) were randomly selected for the training file and consequent decision rules. The remained 98 samples were used for the testing file. The seroprevalence showed a pattern of spatial distribution that involved all the Pantanal area, without agglomeration of reagent animals. In relation to data mining, from 189 samples used in decision tree, a total of 165 (87.3%) animal samples were correctly classified, generating a Kappa index of 0.413. A total of 154 out of 159 (96.8%) samples were considered non-reagent and were correctly classified and only 5/159 (3.2%) were wrongly identified. on the other hand, only 11 (36.7%) reagent samples were correctly classified, with 19 (63.3%) samples failing diagnosis.Discussion: The spatial distribution that involved all the Pantanal area showed that all the animals in the area are at risk of contamination by Leptospira spp. Although most samples had been classified correctly by the decision tree, a degree of difficulty of separability related to seropositive animals was observed, with only 36.7% of the samples classified correctly. This can occur due to the fact of seronegative animals number is superior to the number of seropositive ones, taking the differences in the pattern of variable behavior. The data mining helped to evaluate the most important risk factors for leptospirosis in an urban poor community of Curitiba. The variables selected by decision tree reflected the important factors about the existence of the disease (default of sewer, presence of rats and rubbish and dogs with free access to street). The analyses showed the multifactorial character of the epidemiology of canine leptospirosis.

Disturbance chemical cues determine changes in spatial occupation by the convict cichlid Archocentrus nigrofasciatus

I studied the effect of disturbance chemical cues on fish that make trade-offs between foraging in an open area and remaining in a safe refuge. I used convict cichlids Archocentrus nigrofasciatus that were either visually exposed to a predator (n = 8) or exposed to water conditioned by chemical cues from disturbed conspecifics (n = 8). Fish visually exposed to a predator decreased their ingestion rate and spent more time in the refuge than in the foraging area, while fish receiving water from frightened conspecifics did not alter their ingestion rate or time spent in the refuge and foraging site, but increased their spatial occupation (i.e., motion). These results suggest that convict cichlids recognized the predator by visual cues. Moreover, disturbance cues are a form of threatening public information that may increase fish spatial occupation due to increased exploring behaviour; but is not sufficiently alarming to alter feeding or increase refuge use. (C) 2004 Elsevier B.V. All rights reserved.

Temporal patterns of parasitism in Diatraea saccharalis Fabr. (Lep., Crambidae) populations at different spatial scales in sugarcane fields in Brazil

Biological control of Diatraea saccharalis is regarded as one of the best examples of successful classical biological control in Brazil. Since the introduction of the exotic parasitoid, Cotesia flavipes, from Pakistan at the beginning of the 1970s, decrease in D. saccharalis infestation in sugarcane fields has been attributed to the effectiveness of this agent. Recently, the native Tachinidae fly parasitoids (Lydella minense and Paratheresia claripalpis) have also been implicated in this success. However, quantitative data confirming the actual contribution of these agents to the control of D. saccharalis are rather limited. The purpose of this study was to investigate the dynamics of the interactions between D. saccharalis and its parasitoids, emphasizing the temporal patterns of parasitism. To investigate this question, a large data set comprising information collected from two sugarcane mills located in the state of São Paulo, Brazil (Barra and Sao Joao sugarcane mills), was analysed. Basically, the data set contained monthly information about the number of D. saccharalis larvae and their parasitoids in each sample (man-hour per sample), the sugarcane varieties cultivated, the age of the sugarcane plants (only at the Sao Joao sugarcane mill) as well as the sugarcane cut at sampling time. The data were collected from March 1984 to March 1997 and from May 1982 to December 1996 for the Barra and Sao Joao sugarcane mills, respectively. Temporal inverse density-dependent parasitism was predominant for both parasitoid species with respect to all spatial scales. Although the temporal pattern of parasitism was not directly density dependent, it was evident that the tachinids and C. flavipes presented positive numerical responses according to variations in D. saccharalis densities through time.

Spatial and temporal population interactions between the parasitoids Cotesia flavipes and Tachinidae flies: considerations on the adverse effects of biological control practice

Biological control of Diatraea saccharalis is regarded as one of the best examples of successful classical biological control in Brazil. Since the introduction of the exotic parasitoid Cotesia flavipes, the decrease of D. saccharalis infestation in sugarcane fields has been attributed to the effectiveness of this agent. Recently, the native tachinid fly parasitoids (Lydella minense and Paratheresia claripalpis) have also been implicated in the success. Here, we investigated the spatial and temporal population interactions between C. flavipes and the tachinid flies, and provide a critical analysis of the biological control practice, focusing on the undesirable effects of introductions of exotic natural enemies. To investigate these questions, a large data set comprising information from two sugarcane mills located in the state of São Paulo, Brazil (Barra and Sao Joao Mills), was analysed. Analysis of the correlation between C. flavipes and tachinid fly population densities through time revealed that such populations were inversely correlated in the Sao Joao Mill and not correlated in the Barra Mill. Logistic regressions were computed to investigate the proportion of sites occupied by the parasitoid species at both mills as a function of time. An increasing trend in the proportion of sites occupied by C. flavipes was observed, with a concomitant decrease of the sites occupied by tachinid flies. This effect was more intense in the Sao Joao Mill. Thus, there is a convincing possibility that constant releases of C. flavipes decreased the tachinid fly populations, resulting in an undesirable effect of biological control practice.

Spatial and temporal distribution of fishing resources exploited by the Manaus fishing fleet, Amazonas, Brazil

Recursos pesqueiros são importantes fontes de renda e alimento para as populações rurais e urbanas na Amazônia. O presente trabalho avalia a pesca e as variáveis ambientais que determinam a produção de pescarias que desembarcam em Manaus, e avalia também a abundância relativa de recursos pesqueiros em diferentes subsistemas na Amazônia Central. A informação coletada no porto de desembarque de pescado de Manaus foi utilizada para testar um novo índice de captura obtido a partir de um modelo de covariância que apresentou as seguintes variáveis significativas: número de pescadores/dia (dias de pesca vezes número de pescadores por viagem); distância do pesqueiro até Manaus; quantidade de gelo que usou durante a viagem; e nível de rio. Não houve nenhuma diferença significativa entre valores médios de captura entre os subsistemas do Purus, Madeira e de Juruá. Estes resultados sugerem que os tributários da margem direita são similares e mais produtivos em termos comerciais. Concluiu-se que a produção corrente varia de acordo com a magnitude de esforço pesqueiro, por variações ambientais, assim como por aspectos operacionais da pesca, particularmente o consumo de gelo.

Spatial electric load forecasting using an evolutionary heuristic

A method for spatial electric load forecasting using elements from evolutionary algorithms is presented. The method uses concepts from knowledge extraction algorithms and linguistic rules' representation to characterize the preferences for land use into a spatial database. The future land use preferences in undeveloped zones in the electrical utility service area are determined using an evolutionary heuristic, which considers a stochastic behavior by crossing over similar rules. The method considers development of new zones and also redevelopment of existing ones. The results are presented in future preference maps. The tests in a real system from a midsized city show a high rate of success when results are compared with information gathered from the utility planning department. The most important features of this method are the need for few data and the simplicity of the algorithm, allowing for future scalability.