Learning in the combinatorial neural model.

The combinatorial neural model (CNM) is a type of fuzzy neural network for classification problems and, more generally, for the mapping between fuzzy multidimensional spaces. Learning in CNM is a complex task spanning the learning of input-neuron membership functions, of the network topology, and of connection weights. In this paper we are concerned with these various aspects of learning in CNM, most notably with the learning of connection weights, whose complexity comes from the existence of nondifferentiable, nonconvex error functions associated with the learning process. We introduce several algorithms for weight learning, most based on subgradient techniques borrowed from the field of nondifferentiable optimization. All algorithms are based on essentially "local" rules, and are therefore amenable to distributed/parallel implementations. Experimental results are provided on the large-scale problem of monitoring the deforestation of the Amazon region on satellite images. What these results indicate is that a hybrid CNM system outperforms previous results obtained with variations of error backpropagation techniques. In addition, this hybrid system has demonstrated robustness in the context under consideration, therefore constituting an attractive alternative.

Safety assessment of HCFC-141b: use as a blowing agent for insulation in building construction and refrigeration.

We have performed a risk assessment to evaluate potential risk to human health that might be associated with the use of HCFC-141b (1,1-dichloro-1-fluoroethane) in rigid foam insulation boards for home sheathing and in foam insulation for refrigerators. Risks presented by the blowing agent itself and its potential contaminants and breakdown products (HCFC-151a, HCFC-1131a, and vinylidene chloride) were evaluated following the standard procedures outlined by the National Academy of Sciences. HCFC-141b showed an equivocal tumorigenic effect in rats (an increase in benign testicular tumors that was not dose related), while vinylidene chloride was associated with an increase in tumor incidence (kidney tumors in mice) in a single study out of 19 in which its carcinogenicity has been investigated. The other two contaminants have not been tested for carcinogenicity, but do show some evidence of genotoxicity in short-term tests. However, even if all of these substances are treated as potential carcinogens, under the anticipated conditions of human exposure the maximum theoretical risk to a resident is less than one in one million (10(-6)). Also, no other toxic effects would be anticipated.

Dual substrate removal by an axenic bacterial culture.

A pure bacterial culture capable of utilizing either L-lysine or 2-chlorophenol (2-CP) as sole carbon source was isolated and used in continuous culture experiments to determine its response to dual substrate limitation by those two compounds. Dilution rate and feed composition were each set at three levels in a two factorial experimental design. The total chemical oxygen demand (COD) of the feed was fixed at 225 mg/L and its composition was varied by changing the ratio of lysine to 2-CP. The effects of the two independent variables (dilution rate and feed composition) on the concentrations of cells, lysine, COD, and dissolved organic carbon (DOC) in the reactors were systematic whereas the effects on the 2-CP concentration were less predictable. The concentrations of the two substrates responded to the two independent variables in a complex interactive manner which is not explained by existing models for dual, substitutable substrates. Rather, the results suggested that the prediction of the fate of a single organic component in a reactor receiving a multicomponent feed is a very difficult task.

Bacteriologia da bile em afeccoes litiasicas das vias biliares.Associacao clinico-radiologica. / Biliary bacteriology in cholelithiasis. Clinical and radiological aspects

Os autores realizaram estudos bacteriologicos de amostras biliares de 55 pacientes submetidos a cirurgia das vias biliares extra-hepaticas devido a colecistopatias litiasicas cronicas e agudas. Relacionaram dados clinicos e radiologicos pre e intra-operatorios com a presenca de bacteriobilia. Obtiveram taxas de positividade de 34,5% para bacterias aerobias e 20% para anaerobias. A analise estatistica dos dados clinicos e bacteriologicos apresentou significancia com relacao a existencia de ictericia, febre, diagnostico de patologia aguda e colangiografia operatoria anormal.Nao houve associacao com o tempo de historia clinica ou com o achado radiologico pre-operatorio

[Bacteriology of the bile in cholecystopathies. Radiological association]. / Bacteriologia da bile em colecistopatias. Associação radiológica.

A clinicobacteriological survey was undertaken in 55 patients undergoing biliary surgery, because of chronic and acute cholecystitis. Some radiological preoperative and operative aspects were analised in order to detect any relation of these aspects with biliary tract infection. The bile cultures were positive in 34,5% and 20,0% for aerobes an anaerobes microorganisms respectively. The microorganisms most frequently isolated were Escherichia coli, Pseudomonas aeruginosa, Klebsiella, Bacteroides sp and Clostridium sp, as aerobian and anaerobian. The statistical analysis showed significance between the presence of bacteria in the biliary tract and pathological operative cholangiography. It had not significance with the radiological preoperative aspects.

Bacteriologia da bile em colecistopatias. Associacao radiologica. / Biliary bacteriology in cholecystopathies.Radiological association

Os autores realizaram estudo bacteriologico de amostras biliares de 55 pacientes submetidos a cirurgia das vias biliares extra-hepatica devido a colecistopatias litiasicas cronicas e agudas. Relacionaram os resultados com aspectos radiologicos pre e intra-operatorios. Obtiveram taxas de positividade de 34,5% para bacterias aerobias e 20,0% para anaerobias. A analise estatistica dos dados radiologicos e bacteriologicos apresentou significancia com relacao a existencia de colangiografia operatoria anormal. Nao houve associacao estatistica significativa com o achado radiologico pre-operatorio