1,750 research outputs found

    Increasing the spatial resolution of agricultural land cover maps using a Hopfield neural network

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    Land cover class composition of remotely sensed image pixels can be estimated using soft classification techniques increasingly available in many GIS packages. However, their output provides no indication of how such classes are distributed spatially within the instantaneous field of view represented by the pixel. Techniques that attempt to provide an improved spatial representation of land cover have been developed, but not tested on the difficult task of mapping from real satellite imagery. The authors investigated the use of a Hopfield neural network technique to map the spatial distributions of classes reliably using information of pixel composition determined from soft classification previously. The approach involved designing the energy function to produce a ‘best guess’ prediction of the spatial distribution of class components in each pixel. In previous studies, the authors described the application of the technique to target identification, pattern prediction and land cover mapping at the sub-pixel scale, but only for simulated imagery.We now show how the approach can be applied to Landsat Thematic Mapper (TM) agriculture imagery to derive accurate estimates of land cover and reduce the uncertainty inherent in such imagery. The technique was applied to Landsat TM imagery of small-scale agriculture in Greece and largescale agriculture near Leicester, UK. The resultant maps provided an accurate and improved representation of the land covers studied, with RMS errors for the Landsat imagery of the order of 0.1 in the new fine resolution map recorded. The results showed that the neural network represents a simple efficient tool formapping land cover from operational satellite sensor imagery and can deliver requisite results and improvements over traditional techniques for the GIS analysis of practical remotely sensed imagery at the sub pixel scale

    Indirect measurement of left ventricular end-diastolic pressure in congestive cardiomyopathy and constrictive pericarditis

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    Pulmonary artery diastolic and pulmonary capillary wedge mean pressures were measured in 30 patients with congestive cardiomyopathy and in 30 patients with constrictive pericarditis. These measurements were compared with left ventricular end-diastolic pressure (LVEDP) to assess their value as indirect measurements of left ventricular function. There was close correlation between the indirect measurements and LVEDP in both disorders: a better statistical correlation was achieved using a power curve than with linear regression, since pulmonary artery diastolic pressure increased disproportionately when LVEDP was high.S. Afr. Med. J., 48, 540 (1974)

    Recent, independent and anthropogenic origins of Trypanosoma cruzi hybrids.

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    The single celled eukaryote Trypanosoma cruzi, a parasite transmitted by numerous species of triatomine bug in the Americas, causes Chagas disease in humans. T. cruzi generally reproduces asexually and appears to have a clonal population structure. However, two of the six major circulating genetic lineages, TcV and TcVI, are TcII-TcIII inter-lineage hybrids that are frequently isolated from humans in regions where chronic Chagas disease is particularly severe. Nevertheless, a prevalent view is that hybridisation events in T. cruzi were evolutionarily ancient and that active recombination is of little epidemiological importance. We analysed genotypes of hybrid and non-hybrid T. cruzi strains for markers representing three distinct evolutionary rates: nuclear GPI sequences (n = 88), mitochondrial COII-ND1 sequences (n = 107) and 28 polymorphic microsatellite loci (n = 35). Using Maximum Likelihood and Bayesian phylogenetic approaches we dated key evolutionary events in the T. cruzi clade including the emergence of hybrid lineages TcV and TcVI, which we estimated to have occurred within the last 60,000 years. We also found evidence for recent genetic exchange between TcIII and TcIV and between TcI and TcIV. These findings show that evolution of novel recombinants remains a potential epidemiological risk. The clearly distinguishable microsatellite genotypes of TcV and TcVI were highly heterozygous and displayed minimal intra-lineage diversity indicative of even earlier origins than sequence-based estimates. Natural hybrid genotypes resembled typical meiotic F1 progeny, however, evidence for mitochondrial introgression, absence of haploid forms and previous experimental crosses indicate that sexual reproduction in T. cruzi may involve alternatives to canonical meiosis. Overall, the data support two independent hybridisation events between TcII and TcIII and a recent, rapid spread of the hybrid progeny in domestic transmission cycles concomitant with, or as a result of, disruption of natural transmission cycles by human activities

    A Comparison Of Dietary Intakes Of Title Iii-C Participants On Home-Delivered Meal And Non-Meal Days

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    U okviru robotom potpomognutog protokola za dijagnozu autizma razvijen je modul za detekciju i praćenje proizvoljnog broja predmeta čije su boje poznate te prepoznavanje gesta u pokretima koje se tim predmetima izvode. Modul je prilagođen za izvođenje na humanoidnom robotu NAO u realnom vremenu. Praćenje predmeta se izvodi na robusan način koji dopušta snažnu interakciju između predmeta slične boje bez da se time gubi identitet pojedinog predmeta, te se pokazalo pouzdanim u realnim uvjetima izvođenja zadatka i u testovima praćenja. Prepoznavanje geste s korisničke je strane intuitivno i kvalitetno prepoznaje pokrete koji se koriste pri izvođenju protokola za dijagnozu.As part of a robot-assisted autism diagnostic protocol, a module has been developed for the detection and tracking of an arbitrary number of objects of known color, as well as recognition of gestures based on the movements made by the objects. The module is built for real-time execution on the NAO humanoid robot. Object tracking is done using a robust method allowing for strong interaction between objects of a similar color without disrupting the tracking of any interacting object, and is shown to be reliable both in real-world conditions as well as in tracking tests. The module's gesture recognition capabilities are intuitive to use and provide quality recognition of all movements used in the diagnostic protocol

    Acebutolol in cardiac arrhythmiaa

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    Acebutolol (Sectral), a new beta-adrenoceptor antagonist, was used in 44 patients with cardiac arrhythmias (53 episodes). It was used intravenously (12,5 and 25 mg), orally (100 mg every 8 hours) or in combination with quinidine. Acebutolol was most effective in supraventricular tachyarrhythmias, to control the ventricular response when digital's was ineffective, as a synergist with quinidine to convert patients to sinus rhythm, or prophylactically to prevent relapse to atrial fibrillation. It also terminated ventricular tachycardia in two patients. Side-effects occurred in three ill patients.S. Afr. Med. J., 48, 821 (1974

    Diagnostic electrocardiographic patterns in Bantu myocardiopathy and constrictive pericarditis

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    The electrocardiogram was analysed in 28 adult Bantu patients with myocardiopathy and 33 with constrictive pericarditis. The over-all pattern was quite distinctive in the two groups. Patients with CP usually had sinus rhythm, notched P waves, low voltage QRS complexes in the standard and precordial leads, a normal QRS duration, no intraventricular conduction defects and a uniform and characteristic pattern of ST-T  wave change in most cases. In contrast, the ECG in MCO shows left ventricular hypertrophy, varying degrees of intraventricular conduction disturbance and patterns simulating myocardial infarction

    A Comparison of Machine Learning Algorithms for Prediction of Past Due Service in Commercial Credit

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    Credit risk modeling has carried a variety of research interest in previous literature, and recent studies have shown that machine learning methods achieved better performance than conventional statistical ones. This study applies decision tree which is a robust advanced credit risk model to predict the commercial non-financial past-due problem with better critical power and accuracy. In addition, we examine the performance with logistic regression analysis, decision trees, and neural networks. The experimenting results confirm that decision trees improve upon other methods. Also, we find some interesting factors that impact the commercials’ non-financial past-due payment

    Multiple mitochondrial introgression events and heteroplasmy in trypanosoma cruzi revealed by Maxicircle MLST and next generation sequencing

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    Background Mitochondrial DNA is a valuable taxonomic marker due to its relatively fast rate of evolution. In Trypanosoma cruzi, the causative agent of Chagas disease, the mitochondrial genome has a unique structural organization consisting of 20–50 maxicircles (∼20 kb) and thousands of minicircles (0.5–10 kb). T. cruzi is an early diverging protist displaying remarkable genetic heterogeneity and is recognized as a complex of six discrete typing units (DTUs). The majority of infected humans are asymptomatic for life while 30–35% develop potentially fatal cardiac and/or digestive syndromes. However, the relationship between specific clinical outcomes and T. cruzi genotype remains elusive. The availability of whole genome sequences has driven advances in high resolution genotyping techniques and re-invigorated interest in exploring the diversity present within the various DTUs. Methodology/Principal Findings To describe intra-DTU diversity, we developed a highly resolutive maxicircle multilocus sequence typing (mtMLST) scheme based on ten gene fragments. A panel of 32 TcI isolates was genotyped using the mtMLST scheme, GPI, mini-exon and 25 microsatellite loci. Comparison of nuclear and mitochondrial data revealed clearly incongruent phylogenetic histories among different geographical populations as well as major DTUs. In parallel, we exploited read depth data, generated by Illumina sequencing of the maxicircle genome from the TcI reference strain Sylvio X10/1, to provide the first evidence of mitochondrial heteroplasmy (heterogeneous mitochondrial genomes in an individual cell) in T. cruzi. Conclusions/Significance mtMLST provides a powerful approach to genotyping at the sub-DTU level. This strategy will facilitate attempts to resolve phenotypic variation in T. cruzi and to address epidemiologically important hypotheses in conjunction with intensive spatio-temporal sampling. The observations of both general and specific incidences of nuclear-mitochondrial phylogenetic incongruence indicate that genetic recombination is geographically widespread and continues to influence the natural population structure of TcI, a conclusion which challenges the traditional paradigm of clonality in T. cruzi

    Coronary blood flow measured by the Xenon-133 washout technique

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    Coronary blood flow was measured by the radioactive xenon (133Xe) washout technique in 13 subjects: 6 controls, 5 patients with coronary artery disease and 2 patients who had undergone aortocoronary saphenous vein bypass grafts. The method did not discriminate between normal subjects and patients with coronary artery disease, but may be useful to the study of blood flow in coronary bypass grafts. In 2 patients changes in coronary flow were associated with a change in the patient's clinical status.S. Afr. Med. J., 48, 175 (1974)
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