Showing papers by "University of Buenos Aires published in 1981"

Hierarchies of Regulations and their Logic

Abstract: We study some of the ways in which the imposition of a partial ordering on a code of laws or regulations can serve to overcome logical imperfections in the code itself. In particular, we first show how partial orderings of a code, and derivative orderings of its power set, may be used to confer uniqueness upon otherwise indefinite derogations by ranking remainders; and second, we show how such orderings may be used to resolve contradictions implicit in a code by a process which we shall call delivery. Finally, we investigate the relations between derogation and delivery, showing that although the two processes appear and are generally assumed to be quite different from each other, nevertheless for finite inconsistent codes, the composite process of derogating and then selecting a remainder turns out to be equipowerful with delivery. For consistent codes, where delivery reduces to its underlying consequence operation and so is of no special interest, the correspondence is with a more general process of ‘relative delivery’. Sections 2 and 3, on derogation and the resolution of contradictions respectively, are written so that they may be read in either order. Section 4, on the relations between the two, depends on both. The study is carried out mathematically, and the reader is assumed to be familiar with elementary properties of partial orderings and consequence operations. Throughout, however, attention is also given to the realities of juridical practice.

Relation between arsenic in drinking water and skin cancer.

Abstract: From observations in the Republic of Argentina it is concluded that the regular intake of drinking water containing more than 0.1 ppm of arsenic leads to clearly recognizable signs of intoxication and ultimately in some cases to skin cancer.

Translating Spanish into logic through logic

Abstract: We discuss the use of logic for natural language (NL) processing, both as an internal query language and as a programming tool. Some extensions of standard predicate calculus are motivated by the first of these roles. A logical system including these extensions is informally described. It incorporates semantic as well as syntactic NL features, and its semantics in a given interpretation (or data base) determines the answer-extraction process. We also present a logic-programmed analyser that translates Spanish into this system. It equates semantic agreement with syntactic weil-formedness, and can detect certain presuppositions, resolve certain ambiguities and reflect relations among sets.

Transparent heat mirrors: influence of the materials on the optical characteristics.

Abstract: Transparent heat mirrors of the antireflecting metal type with a dielectric/metal/dielectric structure are studied. It is found that dielectrics of lower refractive index give a higher cutoff wavelength, but the transition becomes more gradual. The angular behavior of these mirrors is also analyzed. The optimum mechanical efficiency obtainable with a plain collector and a carnot engine is given for different concentrations and refractive indices. Moreover it appears that using Al instead of Ag introduces appreciable absorption losses (~25-35%).

Coagulation Studies in Argentine Hemorrhagic Fever

Abstract: Coagulation studies were performed on samples taken from day 6 to day 22 after the onset of symptoms from 32 patients with Argentine hemorrhagic fever, grouped by clinical form into 17 mild cases, nine moderate cases, and six severe cases. The profiles of the coagulation factors during the course of disease were similar in all patients. Partial thromboplastin time activated with kaolin was prolonged in the early stages (78.0 +/- 5.8 sec on day 6 and 47.5 +/- 1.9 sec on day 14). Values for factors II and VII-X remained in the normal range, but factor V activity was greatly enhanced (257.6% +/- 54.7% on day 10). Coagulation alterations tended to normalize after day 14. Fibrinogen profiles differed in the three clinical forms; on day 12 the fibrinogen level increased to 532 +/- 39.3 mg/100 ml in the moderate disease form and to 472 +/- 40.9 mg/100 ml in the severe form. Neither fibrin monomers for fibrinogen degradation products were detected.

Junin Virus Infection of Guinea Pigs: Immunohistochemical and Ultrastructural Studies of Hemopoietic Tissue

Abstract: An association between viral antigens, cytopathic effect (CPE), and viral titers in blood and lymphoid tissues suggests a direct CPE of Junin virus on the lymphopoietic organs of guinea pigs infected with 103 50070 lethal doses of the XJ prototype strain. After seven days of infection, all lymphoreticular organs had infectivity titers higher than those for blood. Virus was recovered from bone marrow and lymph nodes at day 5 after infection; peak titers were obtained from bone marrow, spleen, and lymph nodes after day 10. Granular specific fluorescence was detected in the cytoplasm of reticular monocytes after day 7; megakaryocytes showed positive fluorescence, but specific staining of other lymphoid cells was not observed. Necrosis of bone marrow, lymph nodes, and spleen was observed after day 9. CPE consisted of overdevelopment of reticuloendoplasmic cisternae of reticulomonocytes and myeloblasts. Typical Junin virus particles were observed. Reticular cells were gradually destroyed, and simultaneous necrosis of surrounding lymphoid cells was observed. Argentine hemorrhagic fever (AHF) is an endemic epidemic disease of the Pampean area of Argentina caused by Junin virus, a member of the arenavirus group. This disease mainly affects rural workers involved in corn harvesting. The major clinical characteristics are malaise, fever, central nervous system involvement, and a pronounced leukopenia and thrombocytopenia with hemorrhagic diathesis [1].

The influence of irradiance and water deficit during fruit development on seed dormancy in Datura ferox L.

Abstract: Summary: The effect on seed dormancy of exposing the mother plants to different environmental conditions was studied in Datura ferox. Reducing incident radiation and withholding water to provoke water stress, during the period from fruit set until seed ripening, caused a decrease in the degree of dormancy of the harvested seeds. A significantly smaller amount of the basic fraction inhibitors was found in the seeds with the lesser degree of dormancy. It is suggested that one of the ways in which the environmental conditions to which the mother plants are exposed can influence seed behaviour is by changing the endogenous inhibitor levels Resume: Influence de l'irradiation et du deficit en eau pendant le developpement du fruit sur la dormance des semences de Datura ferox L. L'effet sur a dormance des semences de l'exposition des plantes meres a diverses conditions de l'environnement eteetudie chez Datura ferox. La reduction de la radiation incidente et la retention de l'eau pour provoquer un choc hydrique durant la periode s'etendant de la formation du fruit jusqu'a la maturation des semences, ont provoque une diminution du degre de dormance chez les semences recoltees. Une quantite significativement plus petite de la fraction basique des inhibiteurs a ete trouvee dans les semences presentant le plus faible degre de dormance. II est suggere que les modifications des niveaux des inhibiteurs endogenes constituent l'une des voies par lesquelles les conditions de l'environnement auquel les plantes meres sont exposees peuvent influencer le comportement des semences. Zusammenfassung Der Einfluss von Belichtung und Wasserdefizit wahrend der Fruchtausbildung auf die Dormanz der Samen von Datura ferox L. Mutterpflanzen von Datura ferox wurden unterschiedlichen Umweltverhaltnissen ausgesetzt und die Auswirkung auf die Dormanz der Samen untersucht. Reduzierter Lichteinfall und Wasserstress wahrend der Zeit des Fruchtansatzes bis zur Samenreife, hatten eine geringere Dormanz der Samen zur Folge. Die weniger dormanten Samen enthielten in der basischen Fraktion signifikant weniger Hemmstoffe. Es wird angenommen, dass Veranderungen im Gehalt der Samen an endogenen Hemmstoffen eine von verschiedenen moglichen Reaktionen der Mutterpflanze auf Umweltbedingungen ist.

Benzodiazepine receptors in rat brain: action of Triton X-100 and localization in relation to the synaptic region.

Abstract: Membranes were isolated from the cerebral cortices of rat brain and submitted to binding with 3H-flunitrazepam (3H-FNZP). Specific binding gave a hyperbolic saturation curve reaching a maximum between 10–12 nM suggesting a single population of sites. By Scatchard analysis a KD = 4 nM and a Bmax = 407 fmol/mg protein was obtained; the Hill number was 0.97. The effect of Triton X-100 was analyzed between concentrations of 6.4 × 10-8 and 5 × 10-1%. With 6.4 × 10-6 and 6.4 × 10-3% there is an activation of the binding without loss of protein. This activation is not reversed by washing. At 6.4 × 10-2% or higher concentrations there is an inhibition that is partially reversed and also solubilization of some receptors. The activation with low detergent is due to an increase in Bmax without change in KD. With 2 × 10-1% and 5 × 10-1% Triton X-100 there is considerable decrease in Bmax and in the latter case, an increase in affinity, as well.The results obtained through the action of Triton X-100 suggest th...

Odor, taste, and flavor perception of some flavoring agents

Abstract: Psychophysical functions for the odor, taste, and flavor of five common flavorings were obtained by the method of magnitude estimation. The stimuli included three simple compounds (vanillin, piperonal, and benzaldehyde) and two complex ones (natural vanilla extract and artificial almond essence). The odor intensity of all the flavorings grew much less rapidly with concentration than did taste intensity. The growth of flavor for the complex substances and piperonal behaved very much like taste. For vanillin and benzaldehyde, the flavor functions resembled taste functions at high concentrations but showed a tendency to flatten at lower concentrations. These findings implied that, at least for some flavorings, the growth of flavor reflects the most salient feature on the particular concentration range studied. At low concentrations odor seems to be the most important feature and so flavor functions are generally flat, but at high concentrations taste becomes the salient feature and so flavor functions steepen.

Tissue specificity of dopamine effects on brain ATPases

Abstract: Dopamine inhibits Mg2+,Na+,K+- and Na+,K+-ATPase activities but does not modify Mg2+-ATPase activity of nerve ending membranes isolated from rat cerebral cortex. In the presence of the soluble fraction of brain, dopamine activates total, Na+,K+-, and Mg2+-ATPases. Dopamine stimulation of nerve ending membrane ATPases is achieved when soluble fractions of brain, kidney, or liver are used. On the other hand, dopamine effects are not observed on kidney or heart ATPase preparations. These results indicate tissue specificity of dopamine effects with respect to the enzyme source; there is no tissue specificity for the requirement of the soluble fraction to achieve stimulation of ATPases by dopamine.

Factor VIII: C and factor VIII R: Ag in Argentine hemorrhagic fever.

Abstract: Factor VIII procoagulant activity (F VIII:C) and factor VIII related antigen (F VIII R: Ag) were investigated in 35 patients with Argentine hemorrhagic fever Since the results obtained in the three clinical forms of the disease were not significantly different, they were tabulated altogether F VIII:C was low in early stages of the disease but increased progressively in later days (days 5-6: 054 +/- 010 I U/ml; days 13-14: 095 +/- 013 IU/ml) In contrast, the levels of F VIII R: Ag were high all along the disease and they returned to normal values during the convalescence period (days 5-6; 258 +/- 054 IU/ml; day 30: 130 +/- 014 IU/ml) The levels of F VIII R: ag were similar in samples drawn before (11 cases) or after (10 cases) the treatment with immune plasma infusion Plasma samples from 12 patients were studied by two-dimensional immunoelectrophoresis The only abnormality found was increased height of the immune precipitation arc

Electrophysiological Evidence for the Existence of Caudate-Caudate Connections

Abstract: Experiments were performed in cats unanesthetized and paralyzed with Flaxedil. The stimulation of the right caudate elicited in the contralateral nucleus, biphasic positive-negative field potentials with latencies between 11-20 msec and peak to peak amplitudes of 132-216 microv. These were the shortest latencies and the highest amplitudes for those potentials evoked by stimulation of the symmetrical positions to recording electrode. However, no responses could be evoked in the caudate tail by stimulation of any part of the opposite nucleus. Lesions of cerebral cortex (sensorimotor cortex or hemidecortication) and thalamus (center median-parafascicular complex and massa intermedia) left the evoked responses in the caudate nucleus unchanged. However, the evoked potentials were suppressed by section of the corpus callosum. Our results suggest direct connections between both caudates, through the corpus callosum.

Neonatal hypothyroidism and early undernutrition in the rat: defective maturation of structural membrane components in the central nervous system.

Abstract: The action of neonatal hypothyroidism and early undernutrition on the lipid and protein composition, as well as, on the activity of 2′3′ cyclic nucleotide 3′ phosphohydrolase was studied in different subcellular fractions isolated from 20 day old hypothyroid and undernourished rats. Based on protein content, a marked decrease (70%) in the recovery of myelin was observed in both experimental conditions. The lipid composition of myelin in both groups was, however, different; while cholesterol, total phospholipids, and total galactolipids decreased in a similar fashion in the two situations; sulfatides and plasmalogens were much more affected in hypothyroid rats.

Electrophysiological study of evoked electrical activity in the pineal gland.

Abstract: Experiments were carried out in rats, unanesthetized, paralyzed and artificially respirated. The electrical activity from the pineal gland was recorded with bipolar electrodes. Field potentials were evoked in the pineal after peripheral (photic and sciatic nerve) and central (septal area, habenular complex and optic tract) stimulations. In general these potentials were biphasic with the exception of that evoked by the sciatic nerve and optic tract, which exhibited a complex response and a triphasic field potential, respectively. Bilateral sympathectomy did not modify the pineal evoked responses, but when the pineal stalk was sectioned all the responses were immediately suppressed after the lesion. On the basis of the above experimental data one could conclude that the bulk of the inputs to the pineal gland come through its stalk. At the present, the physiological significance of these findings is not clear.