Browsing by Autor "P. Miranda Loza"

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Control de soldadura industrial mediante rayos-X tendido de tubería Ovejuyo-Pampahasi
(1998) P. Miranda Loza
1 This study aimed to determine the role of the vascular endothelium on recovery of contractile function following global low-flow ischaemia of guinea-pig isolated working hearts and the effects of adenosine analogues on this recovery. 2 Guinea-pig isolated spontaneously beating or paced working hearts were set up and coronary flow (CF), aortic output (AO) (as an index of cardiac function), heart rate (HR), left ventricular pressure (LVP) and dP/dt max recorded. The endothelium was either intact or removed by a blast of oxygen. 3 In spontaneously beating hearts, low-flow ischaemia for 30 min reduced CF and cardiac contractility (LVP, dP/dt max) but not AO. On reperfusion, CF, LVP and dP/dt max recovered, while AO fell precipitously followed by a gradual recovery, indicative of myocardial stunning. The effects of ischaemia did not differ between endothelium-intact and -denuded hearts, indicating no role of the endothelium in the changes observed. 4 The adenosine analogues, N6-cyclopentyladenosine (CPA, A1 selective), 5'-N-ethylcarboxamidoadenosine (NECA, two-fold A2 selective over A1) and 2-p-((carboxyethyl)-phenethylamino)-5'carboxamidoadenosine (CGS21680, A2A selective) were infused (3 x 10-7 M) from 10 min into the 30-min low-flow ischaemia of denuded hearts and during reperfusion. 5 CGS21680 increased CF and improved the postischaemic functional recovery, as measured by the AO. NECA and CPA were not cardioprotective. The A2A selective antagonist, ZM241385, attenuated the coronary vasodilatation by CGS21680 and abolished the improved recovery of AO on reperfusion. 6 Reperfusion of paced working hearts caused a dramatic fall in AO which failed to recover. Infusion of CGS21680 from 15 min into the ischaemic period produced vasodilatation but failed to restore AO, presumably because the ischaemic damage was irreversible. 7 Thus, the endothelium plays no role in myocardial dysfunction following low-flow global ischaemia and reperfusion of guinea-pig working hearts. The A2A adenosine receptor-selective agonist but not the non-selective A2 receptor agonist, NECA, attenuated ischaemia- and reperfusion-induced stunning. This was attributed to increased CF and was independent of the endothelium.
INTERCOMPARACION DE LOS REGISTROS DE LOS OBSERVATORIOS DE VILLA REMEDIOS Y PATACAMAYA
(2008) Edgar Ricaldi Yarvi; P. Miranda Loza
RESUMEN Los registros magneticos del observatorio de Villa Remedios (REM), obte- nidos con equipo digital moderno, y los registros del observatorio de Patacamaya (PTY), obtenidos con equipo analogico antiguo, instalados en sitios diferentes, fueron sometidos al analisis de espectros de amplitudes y frecuencias, practica- dos en registros de intervalos de tiempo cada vez menores, hasta aproximarnos a la frecuencia maxima de 0, 0083Hz, que es la permitida por el instrumento. Las correlaciones realizadas nos permiten estimar que el observatorio antiguo dispone de sensores (agujas magneticas suspendidas) mas sensibles que los del observatorio moderno (bobinas, que trabajan en modo Flux Gate). Sin embargo, cabe informar que los registros del observatorio moderno estan sometidos a un r´i gido control y a un m´ i nimo numero de fuentes de error. La automatizacion del observatorio antiguo, y su puesta en funcionamiento en el mismo punto en que se encuentra localizado el observatorio moderno, permitir´ i a resolver esta controversia. Descriptores: geomagnetismo — procedimientos de laboratorio — registro y procesa- miento de datos ABSTRACT The magnetic records of the observatory of Villa Remedios (REM), obtai- ned from modern digital equipment, and those of the observatory of Patacamaya (PTY), obtained from old analogical equipment, installed in different locations were submitted to a spectral analysis of amplitudes and frequencies. The analy- sis involved recording ever shorter time intervals until reaching the instruments maximum frequency of 0, 0083Hz. The correlations realized indicate that the old observatory has sensors (pendent magnetic needles) that are more sensitive than those of the modern observatory (coils of the Flux Gate type). However, the records of the modern observatory are subject to rigid control and minimal sources of error. The automation of the old observatory and its functioning in the same place as the modern one would allow to solve this controversy.
Use of water-Cherenkov detectors to detect Gamma Ray Bursts at the Large Aperture GRB Observatory (LAGO)
(Elsevier BV, 2008) D. Allard; I. Allekotte; C. Álvarez; H. Asorey; H. Barros; X. Bertou; O. Burgoa; M. Gómez Berisso; O. Martı́nez; P. Miranda Loza