3,416 research outputs found
Art Neural Networks for Remote Sensing: Vegetation Classification from Landsat TM and Terrain Data
A new methodology for automatic mapping from Landsat Thematic Mapper (TM) and terrain data, based on the fuzzy ARTMAP neural network, is developed. System capabilities are tested on a challenging remote sensing classification problem, using spectral and terrain features for vegetation classification in the Cleveland National Forest. After training at the pixel level, system performance is tested at the stand level, using sites not seen during training. Results are compared to those of maximum likelihood classifiers, as well as back propagation neural networks and K Nearest Neighbor algorithms. ARTMAP dynamics are fast, stable, and scalable, overcoming common limitations of back propagation, which did not give satisfactory performance. Best results are obtained using a hybrid system based on a convex combination of fuzzy ARTMAP and maximum likelihood predictions. A prototype remote sensing example introduces each aspect of data processing and fuzzy ARTMAP classification. The example shows how the network automatically constructs a minimal number of recognition categories to meet accuracy criteria. A voting strategy improves prediction and assigns confidence estimates by training the system several times on different orderings of an input set.National Science Foundation (IRI 94-01659, SBR 93-00633); Office of Naval Research (N00014-95-l-0409, N00014-95-0657
ART and ARTMAP Neural Networks for Applications: Self-Organizing Learning, Recognition, and Prediction
ART and ARTMAP neural networks for adaptive recognition and prediction have been applied to a variety of problems. Applications include parts design retrieval at the Boeing Company, automatic mapping from remote sensing satellite measurements, medical database prediction, and robot vision. This chapter features a self-contained introduction to ART and ARTMAP dynamics and a complete algorithm for applications. Computational properties of these networks are illustrated by means of remote sensing and medical database examples. The basic ART and ARTMAP networks feature winner-take-all (WTA) competitive coding, which groups inputs into discrete recognition categories. WTA coding in these networks enables fast learning, that allows the network to encode important rare cases but that may lead to inefficient category proliferation with noisy training inputs. This problem is partially solved by ART-EMAP, which use WTA coding for learning but distributed category representations for test-set prediction. In medical database prediction problems, which often feature inconsistent training input predictions, the ARTMAP-IC network further improves ARTMAP performance with distributed prediction, category instance counting, and a new search algorithm. A recently developed family of ART models (dART and dARTMAP) retains stable coding, recognition, and prediction, but allows arbitrarily distributed category representation during learning as well as performance.National Science Foundation (IRI 94-01659, SBR 93-00633); Office of Naval Research (N00014-95-1-0409, N00014-95-0657
Differences in both prevalence and titre of specific immunoglobulin E among children with asthma in affluent and poor communities within a large town in Ghana.
Background Reports from several African countries have noted an increasing prevalence of asthma in areas of extensive urbanization. Objective To investigate the relevance of allergen-specific sensitization and body mass index (BMI) to asthma/wheezing and exercise-induced bronchospasm (EIB) among children from affluent and poorer communities within a large town in Ghana. Methods Children with physician-diagnosed asthma and/or current wheezing aged 9-16 years (n=99; cases) from three schools with differing socio-economic backgrounds [urban affluent (UA), urban poor (UP) or suburban/rural (SR)] were recruited from a cross-sectional study (n=1848) in Kumasi, Ghana, and matched according to age, sex and area of residence with non-asthmatic/non-wheezy controls. We assayed sera for IgE antibodies to mite, cat, dog, cockroach, Ascaris and galactose-Ī±-1,3-galactose. Results Children from the UA school had the lowest total serum IgE. However, cases from the UA school had a higher prevalence and mean titre of sIgE to mite (71.4%, 21.2IU/mL) when compared with controls (14.3%, 0.8IU/mL) or cases from UP (30%, 0.8IU/mL) and SR community (47.8%, 1.6IU/mL). While similar findings were observed with EIB in the whole population, among cases there was no difference in IgE antibody prevalence or titre between children with or without EIB. BMI was higher among UA children with and without asthma; in UP and SR communities, children with EIB (n=14) had a significantly higher BMI compared with children with asthma/wheezing without EIB (n=38) (18.2 vs. 16.4, respectively, P<0.01). Conclusions and Clinical Relevance In the relatively affluent school, asthma/wheezing and EIB were associated with high titre IgE antibodies to mite, decreased total IgE, and increased BMI. This contrasted with children in the urban poor school and suggests that changes relevant to a Western model of childhood asthma can occur within a short geographical distance within a large city in Africa. Ā© 2011 Blackwell Publishing Ltd
A solvable model of the evolutionary loop
A model for the evolution of a finite population in a rugged fitness
landscape is introduced and solved. The population is trapped in an
evolutionary loop, alternating periods of stasis to periods in which it
performs adaptive walks. The dependence of the average rarity of the population
(a quantity related to the fitness of the most adapted individual) and of the
duration of stases on population size and mutation rate is calculated.Comment: 6 pages, EuroLaTeX, 1 figur
Human response to vibration in residential environments (NANR209), executive summary
The aim of the Defra-funded project NANR209 āHuman response to vibration in residential environmentsā was to develop exposure-response relationships for vibration experienced in residential environments from sources outside of the residentsā control. The project was performed at the University of Salford between January 2008 and March 2011. The final report was published on the Defra website on 6th September 2012.
The NANR209 Final Report consists of the following documents:
ā¢ Executive summary
ā¢ Final project report
ā¢ Technical report 1: Measurement of vibration exposure
ā¢ Technical report 2: Measurement of response
ā¢ Technical report 3: Calculation of vibration exposure
ā¢ Technical report 4: Measurement and calculation of noise exposure
ā¢ Technical report 5: Analysis of the social survey findings
ā¢ Technical report 6: Determination of exposure-response relationships
This document is the Executive summary
Preliminary evaluation of the airborne imaging spectrometer for vegetation analysis
The primary goal of the project was to provide ground truth and manual interpretation of data from an experimental flight of the Airborne Infrared Spectrometer (AIS) for a naturally vegetated test site. Two field visits were made; one trip to note snow conditions and temporally related vegetation states at the time of the sensor overpass, and a second trip following acquisition of prints of the AIS images for field interpretation. Unfortunately, the ability to interpret the imagery was limited by the quality of the imagery due to the experimental nature of the sensor
Establishing a gold standard for manual cough counting: video versus digital audio recordings
BACKGROUND: Manual cough counting is time-consuming and laborious; however it is the standard to which automated cough monitoring devices must be compared. We have compared manual cough counting from video recordings with manual cough counting from digital audio recordings. METHODS: We studied 8 patients with chronic cough, overnight in laboratory conditions (diagnoses were 5 asthma, 1 rhinitis, 1 gastro-oesophageal reflux disease and 1 idiopathic cough). Coughs were recorded simultaneously using a video camera with infrared lighting and digital sound recording. The numbers of coughs in each 8 hour recording were counted manually, by a trained observer, in real time from the video recordings and using audio-editing software from the digital sound recordings. RESULTS: The median cough frequency was 17.8 (IQR 5.9ā28.7) cough sounds per hour in the video recordings and 17.7 (6.0ā29.4) coughs per hour in the digital sound recordings. There was excellent agreement between the video and digital audio cough rates; mean difference of -0.3 coughs per hour (SD Ā± 0.6), 95% limits of agreement -1.5 to +0.9 coughs per hour. Video recordings had poorer sound quality even in controlled conditions and can only be analysed in real time (8 hours per recording). Digital sound recordings required 2ā4 hours of analysis per recording. CONCLUSION: Manual counting of cough sounds from digital audio recordings has excellent agreement with simultaneous video recordings in laboratory conditions. We suggest that ambulatory digital audio recording is therefore ideal for validating future cough monitoring devices, as this as this can be performed in the patients own environment
Human response to vibration in residential environments (NANR209), Technical report 6 : determination of exposure-response relationships
This technical report presents the development of exposure-response relationships for the human response to vibration in residential environments. The data used to formulate the relationships presented in this report are those which were collected for the Defra funded project āNANR209: Human response to vibration in residential environmentsā, the main aim of which was the development of exposure-response relationships. Vibration caused by railway traffic, construction work, and internal sources outside of the residentsā control were considered. Response data was collected via face to face interviews with residents in their own homes. The questionnaire was presented as a neighbourhood satisfaction survey and gathered information on, among other things, annoyance caused by vibration and noise exposure. Development and implementation of the questionnaire used for the collection of response data is discussed in Technical Report 2 and Technical Report 5. Vibration exposure was determined via measurement and prediction in such a way that, where possible, an estimation of internal vibration exposure was established for each residence in which a questionnaire was completed. The measurement procedures and methods employed to estimate vibration exposure are detailed in Technical Report 1 and Technical Report 3. Estimations of noise exposure were also derived for each residence using the methods detailed in Technical Report 4
Near-Real-Time Monitoring of Insect Defoliation Using Landsat Time Series
Introduced insects and pathogens impact millions of acres of forested land in the United States each year, and large-scale monitoring efforts are essential for tracking the spread of outbreaks and quantifying the extent of damage. However, monitoring the impacts of defoliating insects presents a significant challenge due to the ephemeral nature of defoliation events. Using the 2016 gypsy moth (Lymantria dispar) outbreak in Southern New England as a case study, we present a new approach for near-real-time defoliation monitoring using synthetic images produced from Landsat time series. By comparing predicted and observed images, we assessed changes in vegetation condition multiple times over the course of an outbreak. Initial measures can be made as imagery becomes available, and season-integrated products provide a wall-to-wall assessment of potential defoliation at 30 m resolution. Qualitative and quantitative comparisons suggest our Landsat Time Series (LTS) products improve identification of defoliation events relative to existing products and provide a repeatable metric of change in condition. Our synthetic-image approach is an important step toward using the full temporal potential of the Landsat archive for operational monitoring of forest health over large extents, and provides an important new tool for understanding spatial and temporal dynamics of insect defoliators
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