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PubMed2004

Concentration of 226Ra in rocks of the southern part of Lower Silesia (SW Poland).

The aim of the article is to present a preliminary description of rocks in the southern part of Lower Silesia and the Sudety Mountains in particular, with regard to 226Ra content. The research demonstrates that the average content of this isotope was 40.4 Bq/kg in the rocks of the southern part of Lower Silesia, and 41.7 Bq/kg in the rocks of the Sudetes. These values are slightly higher than the mean 226Ra content in the upper part of the Earth's crust, while the measured maximum content of this isotope (244 Bq/kg) is more than twice as high as the upper range of the values most frequently recorded in the upper part of the Earth's crust. The minimum values were lower than the detection limit, which was about 1 Bq/kg. These results reflect the mosaic-like geological structure of Lower Silesia, and particularly the Sudety Mountains, the occurrence of SiO2-rich igneous rocks and the products of their metamorphism, as well as numerous manifestations of uranium mineralisation or even deposital concentrations of this element. The rocks with the highest 226Ra contents include (in decreasing order): aplites, granites, gneisses and leucogranites, granite-gneisses, granodiorites and rhyolites, and, finally, mudstones. The lowest values of 226Ra content, on the other hand, were measured in sandstones, marls and conglomerates, and extremely low-in marbles and quartzites. The results show that background values of 226Ra content in the rocks of the southern part of Lower Silesia fall within a range from several to about 100 Bq/kg, which is the same as the range most frequently recorded in the upper part of the Earth's crust. Distribution of these values has log-normal character. The research demonstrates that the southern part of Lower Silesia, and the Sudetes in particular, may be marked by an increased radon potential. Particularly liable areas are: the Karkonosze granite massif, especially in its border zones, the Ladek-Snieznik and the Izera massifs, especially in their gneiss parts, as well as the Orlica massif. There is an urgent necessity to undertake more extensive and detailed research into this subject in connection with radiological hazard of radon. These statements are compliant with observed high radon concentrations in some groundwaters and tourist underground objects on these areas.

Geology↗
PubMed2004

Radon concentrations in groundwaters of the Polish part of the Sudety Mountains (SW Poland).

In the course of researches into radon occurrence in the groundwaters of the Polish part of the Sudety Mountains, conducted in various research centres in Poland, almost 1000 radon concentration determinations have been collected. These results have given the basis for an attempt to characterise the groundwaters of this region with respect to radon content. Radon concentrations oscillated within the range of 0.2-1645 Bq/dm3, with the arithmetic mean at 240.0 Bq/dm3 and the geometric mean at 106.7 Bq/dm3. The largest number of radon concentrations found in the Sudetic groundwaters ranged between ca. 3-6 and 1000 Bq/dm3. The values over 1000 Bq/dm3 can be considered anomalously high. They constitute 3.9% of all the results and occur around six localities within different geological units of the Sudety Mountains. These are shallow circulation, low mineralised groundwaters, which outflow from gneisses and granites. In the face of the fact that from 12.8% to 72.7% (depending on the adopted norm of maximum radon concentration for drinking waters) of the examined waters cannot be drunk directly without removing at least part of the radon, and in the face of the possibility of recognizing as many as 63.5% of the waters as potentially medicinal, extensive research of radon geochemistry in the Sudety Mountains area should be urgently undertaken.

Altitude↗
PubMed2005

Classification of motor commands using a modified self-organising feature map.

In this paper, a control system for an advanced prosthesis is proposed and has been investigated in two different biological systems: (1) the spinal withdrawal reflex system of a rat and (2) voluntary movements in two human males: one normal subject and one subject with a traumatic hand amputation. The small-animal system was used as a model system to test different processing methods for the prosthetic control system. The best methods were then validated in the human set-up. The recorded EMGs were classified using different ANN algorithms, and it was found that a modified self-organising feature map (SOFM) composed of a combination of a Kohonen network and the conscience mechanism algorithm (KNC) was superior in performance to the reference networks (e.g. multi-layer perceptrons) as regards training time, low memory consumption, and simplicity in finding optimal training parameters and architecture. The KNC network classified both experimental set-ups with high accuracy, including five movements for the animal set-up and seven for the human set-up.

Adult↗
PubMed2004

Marginal median SOM for document organization and retrieval.

The self-organizing map algorithm has been used successfully in document organization. We now propose using the same algorithm for document retrieval. Moreover, we test the performance of the self-organizing map by replacing the linear Least Mean Squares adaptation rule with the marginal median. We present two implementations of the latter variant of the self-organizing map by either quantifying the real valued feature vectors to integer valued ones or not. Experiments performed using both implementations demonstrate a superior performance against the self-organizing map based method in terms of the number of training iterations needed so that the mean square error (i.e. the average distortion) drops to the e(-1) = 36.788% of its initial value. Furthermore, the performance of a document organization and retrieval system employing the self-organizing map architecture and its variant is assessed using the average recall-precision curves evaluated on two corpora; the first comprises of manually selected web pages over the Internet having touristic content and the second one is the Reuters-21578, Distribution 1.0.

Algorithms↗
PubMed2004

Re-experiencing old memories via hippocampus: a PET study of autobiographical memory.

The time-scale of medial temporal lobe (MTL) involvement in storage and retrieval of episodic memory is keenly debated. To test competitive theories of long-term memory consolidation, the present work aimed at characterizing which cerebral regions are involved during retrieval of recent and remote strictly episodic autobiographical memory. Using positron emission tomography (PET), we examined mental retrieval of recent (0-1 year) and remote (5-10 years) autobiographical memories, controlling for the nature of the autobiographical memories (i.e., specificity, state of consciousness, vividness of mental visual imagery, emotion) retrieved during scanning by behavioral measures assessed at debriefing for each event recalled. Cognitive results showed that specificity and emotion did not change with time interval although both autonoetic consciousness and mental image quality were significantly higher for recent memories, suggesting an underlying shift in the phenomenal experience of remembering with the passage of time. The SPM analysis revealed common activations during the recollection of recent and remote memories that involved a widespread but mainly left-sided cerebral network, consistent with previous studies. Subtraction analysis demonstrated that the retrieval of recent (relative to remote) autobiographical memories principally activated the left dorsolateral prefrontal cortex whereas the retrieval of remote (relative to recent) autobiographical memories activated the inferior parietal cortex bilaterally. ROIs analysis revealed more hippocampal activity for remote memories than for recent ones and a preferentially right-sided involvement of the hippocampal responses whatever the remoteness of autobiographical memories. New insights based on higher hippocampal response to the remoteness of episodic autobiographical memories challenge the standard model and are less discrepant with the multiple trace theory.

Adult↗
PubMed2004

Surface-based approaches to spatial localization and registration in primate cerebral cortex.

Explicit surface reconstructions provide invaluable substrates for visualizing and analyzing the complex convolutions of cerebral cortex. This report illustrates the utility of surface-based atlases of human and macaque monkey for representing many aspects of cortical organization and function. These include a variety of cortical partitioning schemes plus an open-ended collection of complex activation patterns obtained from fMRI studies. Surface-based registration from one hemisphere to an atlas provides powerful approach to (i) objectively and quantitatively representing both the consistencies and the variability of the pattern of convolutions and the patterns of functional activation from any given task; and (ii) making comparisons across species and evaluating candidate homologies between cortical areas or functionally delineated regions.

Animals↗
PubMed2005

Ecphory of autobiographical memories: an fMRI study of recent and remote memory retrieval.

Ecphory occurs when one recollects a past event cued by a trigger, such as a picture, odor, or name. It is a central component of autobiographical memory, which allows us to "travel mentally back in time" and re-experience specific events from our personal past. Using fMRI and focusing on the role of medial temporal lobe (MTL) structures, we investigated the brain bases of autobiographical memory and whether they change with the age of memories. Importantly, we used an ecphory task in which the remote character of the memories was ensured. The results showed that a large bilateral network supports autobiographical memory: temporal lobe, temporo-parieto-occipital junction, dorsal prefrontal cortex, medial frontal cortex, retrosplenial cortex and surrounding areas, and MTL structures. This network, including MTL structures, changed little with the age of the memories.

Adult↗
PubMed2004

Do high functioning persons with autism present superior spatial abilities?

This series of experiments was aimed at assessing spatial abilities in high functioning individuals with autism (HFA), using a human-size labyrinth. In the context of recent findings that the performance of individuals with HFA was superior to typically developing individuals in several non-social cognitive operations, it was expected that the HFA group would outperform a typically developing comparison group matched on full-scale IQ. Results showed that individuals with autism performed all spatial tasks at a level at least equivalent to the typically developing comparison group. No differences between groups were found in route and survey tasks. Superior performance for individuals with HFA was found in tasks involving maps, in the form of superior accuracy in graphic cued recall of a path, and shorter learning times in a map learning task. We propose that a superior ability to detect [Human Perception and Performance 27 (3) (2001) 719], match [Journal of Child Psychology and Psychiatry 34 (1993) 1351] and reproduce [Journal of Child Psychology and Psychiatry 40 (5) (1999) 743] simple visual elements yields superior performance in tasks relying on the detection and graphic reproduction of the visual elements composing a map. Enhanced discrimination, detection, and memory for visually simple patterns in autism may account for the superior performance of persons with autism on visuo-spatial tasks that heavily involve pattern recognition, either in the form of recognizing and memorizing landmarks or in detecting the similarity between map and landscape features. At a neuro-anatomical level, these findings suggest an intact dorso-lateral pathway, and enhanced performance in non social tasks relying on the infero-temporal pathway.

Adolescent↗
PubMed2005

Mapping the results of extensive surveys: the case of atmospheric biomonitoring and terrestrial mosses.

In this paper we discuss some difficulties associated with the process of constructing maps of pollution from data obtained in surveys covering extensive areas. As we show here, these problems may be wide-ranging but are seldom recognized by investigators. The origin of the problems is the existence of multiple sources of pollution in the study area, each of different intensity and affecting areas of different extent. The particular spatial structure of the pollution sources interacts with the spatial layout of the samples, resulting in data sets with distributions that are very different from the usually assumed normal distribution, and characterized by heavy tails and gross outliers. These distributions arise because of incomplete sampling of small-scale pollution processes (i.e. those occurring on a spatial scale smaller than the spatial scale of the sampling grid). After discussion of the potential problems and appropriate techniques for analyzing this kind of data, we applied the proposed techniques to a real data set of heavy metal contents in terrestrial mosses. From the exercise we concluded that a) the first step in analysis of this kind of data must be to check for the presence of spatial structure on scales larger than the sampling grid, to avoid mapping noise, and b) the map generated must not contain information about pollution sources with a spatial scale smaller than the spatial scale of the sampling grid. We present and discuss the performance of robust statistical methods of testing for spatial structure (based on robust variograms and randomization testing) and of filtering the small-scale spatial processes (using median-polishing) prior to mapping.

Atmosphere↗
PubMed2000

Topographical disorientation consequent to amnesia of spatial location in a patient with right parahippocampal damage.

We describe a patient who selectively lost the ability to orient himself in the environment after a stroke involving the right parahippocampal gyrus. The neuropsychological assessment showed a specific pattern of impairment of topographical memory; the patient recognised and recalled environmental landmarks but was unable to recall their spatial location. This study provides evidence that different forms of topographical disorientation may be related to distinct mechanisms of cognitive dysfunction. Furthermore, neuroimaging data suggest that a lesion of the right parahippocampal gyrus is critically related to pure topographical disorientation.

Aged↗
PubMed2001

A new approach for detecting and mapping sewage impacts.

Increased nitrogen loading has been implicated in eutrophication occurrences worldwide. Much of this loading is attributable to the growing human population along the world's coastlines. A significant component of this nitrogen input is from sewage effluent, and delineation of the distribution and biological impact of sewage-derived nitrogen is becoming increasingly important. Here, we show a technique that identifies the source, extent and fate of biologically available sewage nitrogen in coastal marine ecosystems. This method is based on the uptake of sewage nitrogen by marine plants and subsequent analysis of the sewage signature (elevated delta 15N) in plant tissues. Spatial analysis is used to create maps of delta 15N and establish coefficient of variation estimates of the mapped values. We show elevated delta 15N levels in marine plants near sewage outfalls in Moreton Bay, Australia, a semi-enclosed bay receiving multiple sewage inputs. These maps of sewage nitrogen distribution are being used to direct nutrient reduction strategies in the region and will assist in monitoring the effectiveness of environmental protection measures.

Environment↗
PubMed1989

Understanding maps as symbols: the development of map concepts in children.

We expect that many readers encountered this article with the beliefs that maps are highly specialized devices primarily used for wayfinding; that they represent the spatial world in a single, correct form; that they are readily transparent; and that their sole contribution to psychology is their role in externalizing environmental cognition. By discussing the myriad functions and forms of maps, by highlighting their symbolic nature, and by considering some of the misconceptions about maps, we have attempted to demonstrate the value of maps for addressing a wide range of developmental questions. Our review of past research literature suggests that research conducted within individual disciplines has both strengths and limitations. Work in the psychological tradition is characterized by attention to important subject characteristics and to carefully described and implemented research designs, procedures, coding, and analyses. At the same time, this work reveals, at best, highly restricted views about maps, and at worst, fundamental misconceptions about maps. Work in the geographic and environmental traditions, in contrast, samples a broader range of map forms and functions, but it suffers from inattention to procedural details that makes the conclusions less compelling than they might otherwise be. A conventional wisdom is emerging from the work in both traditions: That children's map understanding occurs extremely early and extremely easily. The limitations of both research traditions, however, suggest the need for caution in accepting this view. Developmental and cartographic theories provide a compelling reason to reexamine the early and easy view and suggest the need for alternative conceptual and empirical approaches. We have argued that future work should integrate the traditions of psychology and geography. Illustrative data from an interdisciplinary program of research were presented. We described work demonstrating the gradual and difficult process of mastering the representational and geometric correspondences that link the map to its referent in the world. Our data suggest that there are significant achievements in map conceptualization (the understanding of the concept of a map), map identification (understanding the formal components of a map), and map utilization (the ability to use maps). Our data support the view that maps are not transparent and that children's abilities to understand, use, and create maps are linked to their developing representational and spatial skills. In concluding, we should acknowledge that we have deliberately pushed interpretations about understanding maps as symbolic representations to the extreme. The reason for this strategy is simple: We believe that work on maps--both in the public schools and in academia--is assumed to be an expendable and irrelevant luxury.(ABSTRACT TRUNCATED AT 400 WORDS)

Child Development↗
PubMed2001

The origins of a new Trypanosoma brucei rhodesiense sleeping sickness outbreak in eastern Uganda.

BACKGROUND: Sleeping sickness, caused by two trypanosome subspecies, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, is a parasitic disease transmitted by the tsetse fly in sub-Saharan Africa. We report on a recent outbreak of T b rhodesiense sleeping sickness outside the established south-east Ugandan focus, in Soroti District where the disease had previously been absent. Soroti District has been the subject of large-scale livestock restocking activities and, because domestic cattle are important reservoirs of T b rhodesiense, we investigated the role of cattle in the origins of the outbreak. METHODS: We identified the origins of cattle entering the outbreak area in the 4 years preceding the outbreak. A matched case-control study was conducted to assess whether the distance of villages from the main market involved with restocking was a risk factor for sleeping sickness. We investigated the spatial clustering of sleeping sickness cases at the start of the outbreak. FINDINGS: Over 50% (1510 of 2796) of cattle traded at the market were reported to have originated from endemic sleeping sickness areas. The case-control study revealed that distance to the cattle market was a highly significant risk factor for sleeping sickness (p<0.001) and that there was a significant clustering of cases (27 of 28) close to the market at the start of the outbreak (p<0.001). As the outbreak progressed, the average distance of cases moved away from the cattle market (0.014 km per day, 95% CI 0.008-0.020 km per day, p<0.001). INTERPRETATIONS: The results are consistent with the disease being introduced by cattle infected with T b rhodesiense imported to the market from the endemic sleeping sickness focus. The subsequent spread of the disease away from the market suggests that sleeping sickness is becoming established in this new focus. Public health measures directed at controlling the infection in the animal reservoir should be considered to prevent the spread of sleeping sickness.

Adult↗
PubMed2003

Olfactory coding in the mammalian olfactory bulb.

There have been a number of recent approaches to the study of olfactory coding, each of which has its advantages and disadvantages. In the present review, we discuss our own work on this topic, which has involved mapping uptake of [14C]2-deoxyglucose across the entire glomerular layer of the rat main olfactory bulb in response to systematically selected pure odorant molecules. Our strategy to understand the olfactory code has involved four approaches. In the first, we determined whether the system encodes odorants in their entirety, or whether it encodes odorants by representing combinations of molecular features that add together to comprise a neural picture of each odorant. Multiple odorant features appeared to be coded by multiple receptors. Our second strategy examined the ways that such features are represented. We stimulated rats with odorants that differed greatly in their molecular structure to be able to identify a set of odorant feature response domains. Our third approach asked how odorants with very small differences in molecular structure are coded, and we found systematic differences in the representation of such features within response domains. Finally, we were able to predict odor perception from the neural representations of odorants that differed in only a single aspect of their structure. Using these strategies, we have been able to learn some of the rules by which the olfactory code operates. These rules have allowed us to predict where previously unmapped molecules would be represented and how differences in molecular representations affect olfactory perceptions.

Animals↗
PubMed2001

GIS approaches to the problem of disease clusters: a brief commentary.

This commentary considers issues raised in a recent article on GIS-based approaches to modeling disease clusters. 'Modeling exposure opportunities' (Sabel, Gatrell & Löytönen et al., 2000. Social Science and Medicine, 50, 1121-37) and the general problem of mapping disease clusters. It notes that the authors' advocate a fundamentally statistical approach, Kerneling estimation, to map the occurrence of a specific illness whose etiology is unknown. Epidemiologists, ironically, have advocated a fundamentally cartographic solution, the cartogram, in addressing the general problem of disease clusters. The advantages and limits of both approaches are reviewed and the potential for their comparison in a single study suggested. Most importantly, perhaps, the commentary seeks to join the epidemiological and medical geographic literatures as they pertain to this analytic problem and medical cartography's potential (GIS-based or traditional) to understand disease etiology.

Algorithms↗
PubMed2002

Making health data maps: a case study of a community/university research collaboration.

This paper presents the main findings from a collaborative community/university research project in Canada. The goal of the project was to improve access to community health information, and in so doing, enhance our knowledge of the development of community health information resources and community/university collaboration. The project built on a rich history of community/university collaboration in Southeast Toronto (SETO), and employed an interdisciplinary applied research and action design. Specific project objectives were to: (1) develop via active community/university collaboration a geographic information system (GIS) for ready access to routinely collected health data, and to study logistical, conceptual and technical problems encountered during system development; and (2) to document and analyze issues that can emerge in the process of community/university research collaboration. System development involved iteration through community user assessment of need, development or refinement of the GIS, and assessment of the GIS by community users. Collaborative process assessment entailed analysis of archival material, interviews with investigators and participant observation. Over the course of the project, a system was successfully developed, and favorably assessed by users. System development problems fell into four main areas: maintaining user involvement in system development, understanding and integrating data, bringing disparate data sources together, and making use of assembled data. Major themes emerging from the community/university collaborative research process included separate community and university cultures, time as an important issue for all involved, and the impact of uncertainty and ambiguity on the collaborative process.

Access to Information↗
PubMed2003

Zones of prevention: the geography of fall injuries in the elderly.

Our investigation of the geography of fall injuries considers the relationship between injury prevention and contextual approaches to health research. We use a geographic information system (GIS) to describe the pattern of emergency department reported falls of the elderly in the Capital Health Region, an administrative health area in Alberta, Canada. We used empirical Bayes estimates to obtain a geographic measure of fall incidence over the study area and a cluster detection statistic to measure the presence of a significant spatial cluster in the region. Inner-city Edmonton had the highest incidence of risk, suburban Edmonton the lowest, and surrounding rural regions and smaller communities had more moderate fall incidence. We argue that descriptive geography can enhance the effectiveness of injury prevention programs by identifying zones of high risk, even when the individual-level and contextual factors that explain the underlying patterns are unknown.

Accidental Falls↗