Showing papers by "National University of Comahue published in 1990"

Zooplankton Dynamics of Lake Escondido (Rio Negro, Argentina), with Special Reference to a Population of Boeckella gracilipes (Copepoda, Calanoida)

Abstract: The zooplancton dynamics and the populations of Boeckella gracilipes Daday of Lake Escondido (Rio Negro, Argentina) were studied from March 1987 to March 1988. Rotifers and Cladocerans showed high densities during spring and summer, while copepods were densest in autumn. The vertical distribution study showed that rotifers prefer upper levels of the water column, while cladocerans and copepods prefer lower levels, especially during thermal stratification. Boeckella gracilipes had a sex ratio biassed toward female, though changes in the sex ratio were observed. The clutch size was high in winter when the proportion of ovigerous females was low. The instantaneous birth rates were low during winter and high in summer. This result is related to the thermal cycle of the lake, by the influence of temperature on egg development time. The mortality rates showed a similar pattern, and maximum values were registered in spring and summer.

Quantum-chemical molecular dynamics applied to S-P metals

Abstract: We use a simple electronic model for the cohesive energy of metals which explicitly considers eigenfunctions and eigenvectors in a single-particle linear-combination-of-atomic-orbitals approach. From them forces are obtained to perform molecular-dynamics calculations or static relaxation. As an application we compare the model predictions to full many-body ab initio and embedded-atom-model calculations applied to structure and energetics of small Na and Al clusters, to bulk Al, and to vacancies in Al. The relevance of the angular forces introduced by the symmetry of the orbitals used is clearly reflected. Advantages and limitations of this approach as well as size restrictions are discussed.

Sobre hendidas y pseudohendidas

Abstract: Entre varios procedimientos que dispone los el espanol para destacar uno de los constituyentes de laoracion, el HENDIMIENTO (o "escision"o "particion";en ingles "cleaving") apela fundamentalmente a recursos gramaticales. Consiste en dividir el material lexico de una clausula de partida (CLQ) en dos miembros mediante la incorporacion de dos marcadores estructurales: el verbo SER y un nexo hipotactico (relativo o conjuncion). En la construccion derivada, hendida o pseudo hendida, se reconocen dos planos: en un primer plano, en la clausula superordinada, el constituyente focalizado; en el plano de fondo, la subordinada, que, al encapsular el resto, le confiere, en principio, el caracter de presupuesto pragmatico, compartido por los interlocutores y que, por lo tanto, queda fuera de discusion.

Phase II trial of cytarabine, cisplatin and vindesine for advanced non-small cell lung cancer.

Abstract: Thirty-two patients with advanced non-small cell lung cancer (NSCLC) were entered in this study to evaluate the efficacy and toxicity of a chemotherapy schedule including cisplatin (C) 40 mg/m2 intravenously (i.v.) on days 1-3; vindesine (V) 3 mg/m2 i.v. on day 1, and cytarabine (ara-C) 15 mg/m2 subcutaneously every 12 hours on days 1-3 (total dose: 90 mg/m2). Cisplatin was administered simultaneously with one dose of ara-C. Cycles were repeated every 28 days. Five patients out of 28 (18%) fully evaluable for response presented partial remissions. No complete response was observed. Median survival was 8 months and median duration of response was 4 months. Hematologic toxicity was severe in 3 patients. There were no toxicity-related deaths. Other adverse reactions included nausea and vomiting, alopecia and peripheral neuropathy. We conclude that this chemotherapy combination is marginally effective against NSCLC showing in this group of patients a low number of responses of short duration without a significant impact on survival.