Jorge Álvarez - Academia.edu (original) (raw)
Papers by Jorge Álvarez
Physics of Plasmas, 2008
A recent analytic solution of the Hall magnetohydrodynamics equations is analyzed. It is shown th... more A recent analytic solution of the Hall magnetohydrodynamics equations is analyzed. It is shown that its evolution in time depends upon a certain set of inequalities upon the initial values of the velocity and the magnetic field. For most of the cases, both magnitudes will blow up in a finite time. This shows that for keeping the original structure of
Early Human Development, 1993
We tested the hypotheses that (1) pretetm infants with bronchopulmonary dysplasia (BPD) have an i... more We tested the hypotheses that (1) pretetm infants with bronchopulmonary dysplasia (BPD) have an increased incidence of obstructive apneas as compared to those without BPD (control) and (2) the respiratory pattern during obstructive apneas may be associated with more pronounced hypoventilation. Ventilation was measured with a flow-through system. We examined 2929 total apneas in 12 infants with BPD and 4366 apneas in 12 control infants matched for study weight (1.51 f 0.11 kg in the BPD group and 1.62 f 0.12 kg in the control group, P = 0.6) and for postconceptional age (33.3 + 0.8 weeks in the BPD group compared with 33.4 f 0.7 weeks in the control group, P = 0.6). The incidence of central apneas predominated in the BPD group (2551/2929, 87%) and in the control group (4188/4366, 96%). Obstructive apneas were more frequent in the BPD group (37812929, 13%) than in the control group (178/4366, 4%, P = 0.004). The increased incidence of obstructive apneas in infants with BPD was observed in Quiet sleep (9.1 vs. 1.6%, P = 0.03) and in REM sleep (14.2 vs. 3.6%, P = 0.009). This increased incidence of obstructive apneas was applicable to short apneas (< 10 s, 10.9 vs. 2.7%, P = 0.003) and long apneas (> 10 s, 27.5 vs. 16.4%, P = 0.01). There were no signiticant changes in ventilatory pattern that could be uniquely attributed to one type of apnea. The findings suggest: (1) the great variability in the incidence of obstructive apneas reported in the literature relates, at least in part, to the clinical status of the infants and (2) ventilatory pattern is not a useful predictor of either type of apnea.
Pediatric Research, 1992
The classic "biphasic" ventilatory response to 15% O2 was previously observed i... more The classic "biphasic" ventilatory response to 15% O2 was previously observed in preterm infants who were large compared with those in the intensive care nursery today. We hypothesized that in the smaller infant (less than or equal to 1500 g) the response might be closer to that of the fetus, with no initial increase in ventilation. Thus, we studied 14 healthy preterm infants less than or equal to 1500 g [birth weight 1200 +/- 63 g (mean +/- SEM); gestational age 29 +/- 0.4 wk; postnatal age 17 +/- 3 d] during rapid eye movement and quiet sleep. Ventilation was measured using a nosepiece and a flow-through system. Sleep states were defined using EEG, electro-oculogram, and body movements. After a control period in 21% O2 (3 min), infants breathed 15% O2 for 5 min. In rapid eye movement sleep, minute ventilation decreased from 0.186 +/- 0.020 (control) to 0.178 +/- 0.021 (30 s), to 0.171 +/- 0.017 (1 min; p = 0.03), to 0.145 +/- 0.016 (3 min; p = 0.002), and to 0.129 +/- 0.011 l.min-1.kg-1 (5 min; p = 0.004). In quiet sleep, it decreased from 0.173 +/- 0.019 (control) to 0.164 +/- 0.019 (30 s), to 0.166 +/- 0.019 (1 min), to 0.148 +/- 0.013 (3 min; p = 0.03), and to 0.146 +/- 0.012 l.min-1.kg-1 (5 min; p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)
Neonatology, 1993
To test the hypothesis that sighs are mechanistically important in triggering apnea, we studied 1... more To test the hypothesis that sighs are mechanistically important in triggering apnea, we studied 10 preterm infants, group 1: body weight 1.8 +/- 0.1 kg, gestational age 33 +/- 1 weeks, postnatal age 21 +/- 4 days, and 10 term infants, group 2: body weight 3.9 +/- 0.15 kg, gestational age 40 +/- 0.4 weeks, postnatal age 1.4 +/- 0.2 days. Instantaneous ventilatory changes associated with a sigh were studied in another 10 preterm infants, group 3: body weight 1.6 +/- 0.11 kg, gestational age 32 +/- 0.4 weeks, postnatal age 25 +/- 4 days. Ventilation was measured using a nosepiece and a flow-through system. Sleep states were recorded. Sighs were more frequent in preterm than in term infants (0.4 +/- 0.04 vs. 0.18 +/- 0.03 sighs/min; p = 0.03) and in rapid eye movement than in quiet sleep (0.5 +/- 0.05 vs. 0.3 +/- 0.05 sighs/min; p = 0.05). Of 722 apneas, 235 (33%) were associated with a sigh; of these, 113 (48%) preceded and 122 (52%) followed a sigh. Sighs induced with airway occlusion (groups 1 and 2) were more frequent after occlusion on 21 than on 35% O2, particularly when O2 saturation was low and negative airway pressure high. Instantaneous ventilation measured over 10 breaths preceding a sigh did not show any trend indicating the possible appearance of a sigh. Tidal volume increased from 7.5 +/- 0.7 before the sigh to 18.9 +/- 0.7 ml/kg (p &amp;lt; 0.01) during a sigh, with a significant increase in inspiratory drive. Ventilation increased from 0.327 +/- 0.041 to 0.660 +/- 0.073 l/min/kg.(ABSTRACT TRUNCATED AT 250 WORDS)
La justicia restaurativa o justicia reparadora es una teoría, a la vez que un movimiento social d... more La justicia restaurativa o justicia reparadora es una teoría, a la vez que un movimiento social de carácter internacional de reforma a la justicia penal, que plantea que el crimen o delito es fundamentalmente un daño en contra de una persona concreta y de las relaciones interpersonales, a diferencia de la justicia penal convencional de carácter retributiva, que plantea que el delito
Physics of Plasmas, 2008
A recent analytic solution of the Hall magnetohydrodynamics equations is analyzed. It is shown th... more A recent analytic solution of the Hall magnetohydrodynamics equations is analyzed. It is shown that its evolution in time depends upon a certain set of inequalities upon the initial values of the velocity and the magnetic field. For most of the cases, both magnitudes will blow up in a finite time. This shows that for keeping the original structure of
Early Human Development, 1993
We tested the hypotheses that (1) pretetm infants with bronchopulmonary dysplasia (BPD) have an i... more We tested the hypotheses that (1) pretetm infants with bronchopulmonary dysplasia (BPD) have an increased incidence of obstructive apneas as compared to those without BPD (control) and (2) the respiratory pattern during obstructive apneas may be associated with more pronounced hypoventilation. Ventilation was measured with a flow-through system. We examined 2929 total apneas in 12 infants with BPD and 4366 apneas in 12 control infants matched for study weight (1.51 f 0.11 kg in the BPD group and 1.62 f 0.12 kg in the control group, P = 0.6) and for postconceptional age (33.3 + 0.8 weeks in the BPD group compared with 33.4 f 0.7 weeks in the control group, P = 0.6). The incidence of central apneas predominated in the BPD group (2551/2929, 87%) and in the control group (4188/4366, 96%). Obstructive apneas were more frequent in the BPD group (37812929, 13%) than in the control group (178/4366, 4%, P = 0.004). The increased incidence of obstructive apneas in infants with BPD was observed in Quiet sleep (9.1 vs. 1.6%, P = 0.03) and in REM sleep (14.2 vs. 3.6%, P = 0.009). This increased incidence of obstructive apneas was applicable to short apneas (< 10 s, 10.9 vs. 2.7%, P = 0.003) and long apneas (> 10 s, 27.5 vs. 16.4%, P = 0.01). There were no signiticant changes in ventilatory pattern that could be uniquely attributed to one type of apnea. The findings suggest: (1) the great variability in the incidence of obstructive apneas reported in the literature relates, at least in part, to the clinical status of the infants and (2) ventilatory pattern is not a useful predictor of either type of apnea.
Pediatric Research, 1992
The classic "biphasic" ventilatory response to 15% O2 was previously observed i... more The classic "biphasic" ventilatory response to 15% O2 was previously observed in preterm infants who were large compared with those in the intensive care nursery today. We hypothesized that in the smaller infant (less than or equal to 1500 g) the response might be closer to that of the fetus, with no initial increase in ventilation. Thus, we studied 14 healthy preterm infants less than or equal to 1500 g [birth weight 1200 +/- 63 g (mean +/- SEM); gestational age 29 +/- 0.4 wk; postnatal age 17 +/- 3 d] during rapid eye movement and quiet sleep. Ventilation was measured using a nosepiece and a flow-through system. Sleep states were defined using EEG, electro-oculogram, and body movements. After a control period in 21% O2 (3 min), infants breathed 15% O2 for 5 min. In rapid eye movement sleep, minute ventilation decreased from 0.186 +/- 0.020 (control) to 0.178 +/- 0.021 (30 s), to 0.171 +/- 0.017 (1 min; p = 0.03), to 0.145 +/- 0.016 (3 min; p = 0.002), and to 0.129 +/- 0.011 l.min-1.kg-1 (5 min; p = 0.004). In quiet sleep, it decreased from 0.173 +/- 0.019 (control) to 0.164 +/- 0.019 (30 s), to 0.166 +/- 0.019 (1 min), to 0.148 +/- 0.013 (3 min; p = 0.03), and to 0.146 +/- 0.012 l.min-1.kg-1 (5 min; p = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)
Neonatology, 1993
To test the hypothesis that sighs are mechanistically important in triggering apnea, we studied 1... more To test the hypothesis that sighs are mechanistically important in triggering apnea, we studied 10 preterm infants, group 1: body weight 1.8 +/- 0.1 kg, gestational age 33 +/- 1 weeks, postnatal age 21 +/- 4 days, and 10 term infants, group 2: body weight 3.9 +/- 0.15 kg, gestational age 40 +/- 0.4 weeks, postnatal age 1.4 +/- 0.2 days. Instantaneous ventilatory changes associated with a sigh were studied in another 10 preterm infants, group 3: body weight 1.6 +/- 0.11 kg, gestational age 32 +/- 0.4 weeks, postnatal age 25 +/- 4 days. Ventilation was measured using a nosepiece and a flow-through system. Sleep states were recorded. Sighs were more frequent in preterm than in term infants (0.4 +/- 0.04 vs. 0.18 +/- 0.03 sighs/min; p = 0.03) and in rapid eye movement than in quiet sleep (0.5 +/- 0.05 vs. 0.3 +/- 0.05 sighs/min; p = 0.05). Of 722 apneas, 235 (33%) were associated with a sigh; of these, 113 (48%) preceded and 122 (52%) followed a sigh. Sighs induced with airway occlusion (groups 1 and 2) were more frequent after occlusion on 21 than on 35% O2, particularly when O2 saturation was low and negative airway pressure high. Instantaneous ventilation measured over 10 breaths preceding a sigh did not show any trend indicating the possible appearance of a sigh. Tidal volume increased from 7.5 +/- 0.7 before the sigh to 18.9 +/- 0.7 ml/kg (p &amp;lt; 0.01) during a sigh, with a significant increase in inspiratory drive. Ventilation increased from 0.327 +/- 0.041 to 0.660 +/- 0.073 l/min/kg.(ABSTRACT TRUNCATED AT 250 WORDS)
La justicia restaurativa o justicia reparadora es una teoría, a la vez que un movimiento social d... more La justicia restaurativa o justicia reparadora es una teoría, a la vez que un movimiento social de carácter internacional de reforma a la justicia penal, que plantea que el crimen o delito es fundamentalmente un daño en contra de una persona concreta y de las relaciones interpersonales, a diferencia de la justicia penal convencional de carácter retributiva, que plantea que el delito