50 years of the water-flow variance in Tucuruí reservoir related with Brazilian energy consumption.

Dammed rivers lose its natural characteristics of the flow cycle and becomes controlled by the energy demands of the hydroelectric plants. With the connection of the energy-producing plants to a central station in Brazil the situation is aggravated since demands in different regions of the country affect the water flow. Using downstream flow data from the Tucuruí dam over a 50-year period, we tested whether the variation in water flow has changed. We observed an increase of the annual variation of the water flow and the extreme events of flooding at downstream of the dam, indicating the operation of the dam intensified the control of water passage. The study reveals an increase in the variation of water flow in the dam's downstream section following the interconnection of the Tucurui dam with the Central System in 1997. Management strategies for the dam should be considered integrated with the national electricity demand, since distant demands may affect the local environment in question.

Alterações fisiológicas e comportamentais de bovinos de corte após o manejo de castração / Physiological and behavioral changes of beef cattle after castration management

Objetivou-se avaliar o desempenho, parâmetros fisiológicos e temperamentais de bovinos de corte não castrados ou submetidos à castração cirúrgica ou à imunocastração. O período experimental foi dividido em dois subperíodos de observações: primeiros 15 dias pós-castração (período de cicatrização) e os 25 dias seguintes à cicatrização. Nos primeiros 15 dias de avaliação, os animais não castrados obtiveram maior ganho médio diário de peso em relação aos castrados cirurgicamente. A frequência cardíaca foi maior para os animais castrados cirurgicamente, com 126,51 batimentos/minuto, em relação aos demais tratamentos. A distância de fuga foi superior para os novilhos castrados cirurgicamente, com valor de 12,22 metros. Nos 25 dias seguintes à castração cirúrgica, o ganho médio diário de peso foi superior nos bovinos castrados cirurgicamente em relação aos bovinos não castrados ou imunocastrados. A velocidade de fuga, no segundo subperíodo de avaliação, foi superior nos bovinos castrados em relação aos não castrados. O período imediato à castração, os primeiros 15 dias, prejudicou o ganho médio diário e o ganho de peso total, o que causou maior reatividade, com alterações nos parâmetros fisiológicos e temperamentais de bovinos castrados cirurgicamente em comparação com bovinos não castrados, entretanto, transcorrido o período de cicatrização, essas diferenças diminuíram ou desapareceram.(AU)

The aim of this study was to evaluate the performance, physiological and temperamental parameters of uncastrated beef cattle or those submitted to surgical castration or immunocastration, in the post-castration period. The experimental period was divided into two subperiods of observations: the first 15 days post-castration (healing period) and the 25 days following healing. In the first 15 days of evaluation, the non-castrated animals obtained a greater average daily gain of weight in relation to surgically castrated. The heart rate was higher for surgically castrated animals with 126,51 beats/minute, compared to the other treatments. The distance of escape was higher for the surgically castrated steers, with a value of 12,22 meters, when compared to the other groups studied. During the next 25 days of surgical castration, the mean daily gain of weight was higher in surgically castrated cattle than in non-castrated or immunocastrated cattle. The escape velocity, in the second evaluation subperiod, was superior in the castrated cattle, in relation to the not castrated. The immediate castration period, the first 15 days, altered the mean daily gain and the total weight gain, the physiological and temperamental parameters of surgically castrated cattle, however, after the healing period, these differences diminish or disappear.(AU)

Dynamics of the O + ClO reaction: reactive and vibrational relaxation processes.

Classical trajectories have been integrated to study the O + ClO reaction, both reactive and vibrational energy transfer processes, for the range of temperatures 100 ≤ T/K ≤ 500 using momentum Gaussian binning. The employed potential energy surface is the recently proposed single-sheeted double many-body expansion potential energy surface for the (2)A" ground-state of ClO2 based on multireference ab initio data. A capture-type regime with a room-temperature rate constant of (17.8 ± 0.5) × 10(-12) cm(3) s(-1) and temperature dependence of k(T/K)/cm(3) s(-1) = 22.4 × 10(-12) × T(-0.81) exp(-39.2/T) has been found. Although the value reported here is half of the experimental and recommended one, tentative explanations are given. Other dynamical attributes are also examined for the title reaction, with state-to-all and state-to-state vibrational relaxation and excitation rate constants reported for temperatures of relevance in stratospheric chemistry.

Single-sheeted double many-body expansion potential energy surface for ground-state ClO2.

A global single-sheeted double many-body expansion potential energy surface is reported for the ground electronic state of ClO2. The potential energy surface is obtained by fitting 3200 energy points that map all atom-diatom dissociation channels as well as all relevant stationary points, including the well-known OClO and ClOO structures. The ab initio calculations are obtained at the multireference configuration interaction level of theory, employing the cc-pVXZ (X = D, T) Dunning basis sets, and then extrapolated to the complete basis set limit with the generalized uniform singlet- and triplet-pair protocol. The topographical features of the novel global potential energy surface are examined in detail.

Cerebral blood flow velocity during tilt table test for pediatric syncope.

BACKGROUND: Brain hypoperfusion during neurocardiogenic syncope develops as a consequence of hypotension and bradycardia. Transcranial Doppler indicates that an increase in cerebral vascular resistance occurs before or during the loss of consciousness. OBJECTIVE: Cerebral blood flow velocity was studied during tilt table testing in pediatric patients with neurocardiogenic syncope. We assessed whether a critical reduction in flow velocity (>40%) was predictive of the presyncopal manifestations during the test. METHODS: A 2-MHz transcranial Doppler measured blood flow velocity in the right middle cerebral artery in 27 pediatric patients (ages, 8 to 18 years) during a three-stage 80 degrees tilt table test protocol. A positive test required development of syncope or presyncope with at least 30% decrease in systolic blood pressure and/or heart rate relative to preceding values. Patients were divided into: group I (isoproterenol-induced positive tests), group II (positive without isoproterenol), and group III (negative tests). RESULTS: Within the first 3 minutes of the upright position mean cerebral blood flow velocity in groups I, II, and III decreased by 18%, 29%, and 17%, respectively, as the systolic and diastolic blood pressures showed only minimal changes. A decreased mean blood flow velocity of 48% and 45% and an increase in resistance index of 42% and 26% from supine values in the absence of hypotension, were detected in groups I and II at 46 seconds (range, 30-120 seconds) and 50 seconds (range, 0-300 seconds) before any clinical symptom (presyncope latency). Mean blood flow velocity during presyncope decreased by 58% and 59%, whereas resistance index was double. A significant correlation (rho = -0.62) was found between presyncope latency and the decreased mean cerebral blood flow velocity. Similar blood flow velocity changes were not detected in group III. CONCLUSION: A sustained reduction >40% in mean cerebral blood flow velocity in the absence of hypotension always resulted in presyncopal or syncopal manifestations. It seems that once this critical threshold is identified during the tilt table testing, supine position may be resumed several seconds before the clinical manifestations of syncope.

Transoesophageal echocardiographic assessment of obstruction to the pulmonary venous pathway in children with Mustard or Senning repair.

The morphology and mechanism of obstruction to the pulmonary venous pathway in patients following either Mustard or Senning repair of complete transposition was assessed using transoesophageal echocardiography. Seven patients underwent catheterization and complete transoesophageal study in both transverse and longitudinal planes, followed by balloon dilation of the obstructed venous pathway in five of seven under transoesophageal echocardiography guidance. A complete scan of both systemic and venous pathway was obtained in all patients. Four patients with a Mustard repair were found to have a 'tubular' baffle, with stenosis resulting from a discrete wedge of tissue arising from the atrial free wall in association with fibrous adhesions to the baffle. In the three patients with a Senning repair the intra-atrial baffle showed a characteristic 'peaked' appearance, with stenosis of the venous pathway stenosis related directly to contracture of the patch used to augment the atrial free wall. The mechanism of obstruction appears to be inherent to the different surgical techniques. Indwelling transoesophageal echocardiography provided immediate haemodynamic and morphologic assessment of the efficacy of dilation of the obstructed venous pathway.

Cerebral blood flow velocities monitored by transcranial Doppler during cardiac catheterizations in children.

Transcranial Doppler (TCD) was used to evaluate brain circulation during cardiac catheterizations in 32 children requiring pulmonary (n=10) or aortic balloon dilatations (n=2), ductus arteriosus coil insertions (n=5), or angiography (n=15). Cerebral blood flow velocity (CBFV) in the middle cerebral artery was measured before (baseline), during, and after each procedure (mean+/-95%ci). High-intensity transient signals (HITS) were also detected during these maneuvers. Balloon angioplasty decreased CBFV by 63+/-11% from baseline (P < 0.01). Shorter durations of the inflation cycle resulted in earlier CBFV recovery (r=0.78). During angiography, CBFV increased by 11+/-4% (P < 0.01) in all except one case that showed retrograde diastolic flow. Mean total HITS count was 44 (95%ci.limits: 27,74). These signals were more frequently found in septal defects or systemic arterial manipulations. Pediatric cardiac catheterization may impose transient fluctuations in brain perfusion as indicated by TCD, but their clinical implications are uncertain. CBFV changes during balloon angioplasty emphasize the importance of rapid inflation/deflation cycles. TCD can monitor such changes and evaluate preventive measures.

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia in children.

Radiofrequency (RF) catheter ablation has been widely used in the treatment of cardiac arrhythmias. In atrioventricular nodal reentrant tachycardia (AVNRT), the experience has been predominantly in adults. The cardiac electrophysiological records of 18 consecutive children undergoing RF catheter AV node modification for AVNRT were reviewed. The patients (10 females, 8 males) were 8.2-17.9 years of age (mean 13.6 +/- 3.0), weight 15.2-88.1 kg (mean 52.2 +/- 20.8), and height 103-190 cm (mean 157.1 +/- 21.7). Thirteen were on antiarrhythmic medications (1-3, average 1.5 drugs/day). All drugs were discontinued 48 hours prior to the ablations. The procedures were performed under sedation and local anesthesia. Pre- and post-AV node modification electrophysiological studies were performed in all procedures. The 18 patients underwent a total of 25 procedures (1.39 +/- 0.61 per patient): the anterior approach aimed at the antegrade fast pathway in the first four patients and the posterior approach aimed at the slow pathway in the remainder. The number of energy applications was 8-54 (19.8 +/- 10.7) per procedure. The maximum energy used in each procedure was 30-50 watts (33.8 +/- 8.4). The average energy was 24-50 watts (33.0 +/- 6.8). The fluoroscopy time was 7.1-73.4 minutes (29.9 +/- 20.0) per procedure, for a total catheterization time of 228-480 minutes (300.3 +/- 59.1). Preablation spontaneous or induced AVNRT (cycle length 310.4 +/- 55.0 msec) was seen in all except one who had the arrhythmia (cycle length 270 msec) on surface ECG.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful repair of recurrent coarctation after neonatal heart transplantation.

Neonatal orthotopic heart transplantation is an attractive primary surgical therapy for severe uncorrectable congenital heart defects such as variants of the hypoplastic left heart syndrome. Aortic arch reconstruction is frequently required to repair the hypoplastic aortic arch and the coarctation at the time of graft implantation. Residual coarctation of the aorta after neonatal heart transplantation for such a condition has satisfactorily been treated with percutaneous balloon dilatation. We describe the successful surgical repair of a recurrent coarctation of the aorta via a sternotomy in a 2-year-old patient who had previously undergone neonatal orthotopic heart transplantation. Postoperative periodic investigations have not shown any evidence of obstruction across the site of the primary end-to-end anastomosis.

Transcatheter management of pulmonary venous pathway obstruction with atrial baffle leak following Mustard and Senning repair.

Two patients presenting with pulmonary venous baffle obstruction following Mustard or Senning repair of transposition of the great arteries were successfully treated with percutaneous balloon dilatation. At the time of baffle dilatation, a significant systemic to pulmonary venous Mustard baffle leak was successfully closed with a Rashkind ductal occluder device. Specific features pertaining to the morphology of the baffle defect that allowed successful catheter occlusion are discussed and compared to that found in a Senning patient. The important adjunctive role of transoesophageal echocardiography within the catheterization laboratory is emphasized.

Initial evaluation of heart murmurs: are laboratory tests necessary?

Heart murmurs, most of them innocent, are the most common reason for referrals to a pediatric cardiologist. In the evaluation of murmurs, the electrocardiogram and echocardiogram are often included. The purpose of this study was to determine the utility of these examinations in the initial assessment of heart murmurs in children and adolescents. In a prospective series of 161 patients, the clinical diagnosis of heart murmurs by a pediatric cardiologist was compared with that obtained after electrocardiogram and echocardiogram (two-dimensional, M-mode, Doppler, and color-Doppler). On the basis of the clinical diagnosis the patients were classified as having "innocent murmur," "pathologic murmur," or "possible pathologic murmur." A total of 161 patients (51% males), aged 1 month to 17 years (median 3.2 years), were studied. After electrocardiogram, no diagnosis was changed. After echocardiogram, the clinical diagnosis of innocent murmur in 109 patients changed in 2 to pathologic (small ventricular septal defect 1, small atrial septal defect 1); pathologic murmur in 46 changed to innocent in 3 and possible pathologic in 2; and possible pathologic in 6 changed to innocent in 3 and to pathologic in 2. The clinical examination by an experienced pediatric cardiologist is an accurate means of assessing newly referred patients with murmurs. The clinical examination had a sensitivity of 96%, specificity of 95%, positive predictive value of 88%, and negative predictive value of 98%. The electrocardiogram, unlikely to disclose any unsuspected heart disease, may assist in reaching the lesion-specific diagnosis when there is underlying pathology. Echocardiography, although diagnostic when heart disease is suspected, is unnecessary in pediatric patients with clinically diagnosed innocent heart murmurs.

Atypical hepatic vein leiomyoma extending into the right atrium: an unusual cause of the Budd-Chiari syndrome.

A 14-year-old male presented with a one week history of weakness, lightheadedness and vomiting. Bilateral pleural effusions were evident on chest radiography; electrocardiogram revealed decreased voltages. Echocardiogram, abdominal ultrasound and magnetic resonance imaging revealed a mass in an hepatic vein and the inferior vena cava extending up to and filling the right atrium. Under deep hypothermia and extracorporeal circulation the mass was removed en bloc. It originated from the hepatic vein. Pathology revealed a smooth muscle tumour intermediate between benign and malignant (atypical leiomyoma). This is the first reported pediatric primary leiomyoma of the hepatic vein. It caused the Budd-Chiari syndrome, a rare pediatric entity.

Idiopathic post-operative pulmonary hypertension in the newborn.

A case of severe pulmonary hypertension following the primary repair of an omphalocele in a term infant is reported. There were no pre-disposing factors known to contribute to the postoperative pulmonary hypertension (PPH). Therapy was successful first by using hyperventilation, and then subsequently with tolazoline. Upper gastrointestinal bleeding limited the use of tolazoline after the first fourty-eight hours. Complete recovery ensued. The occurrence of PPH and the current therapy of this unpredictable condition is discussed.

Long-term prostaglandin E1 therapy in congenital heart defects.

Seventeen neonates received an intravenous infusion of prostaglandin E1 for an average of 39 days (range 8 to 104). Seven (group 1) had transposition of the great arteries with no ventricular septal defect or a small one; eight (group 2) had ductus-dependent pulmonary flow (pulmonary atresia or stenosis in six and tricuspid atresia in two); and two (group 3) had aortic coarctation, one with no ventricular septal defect, the other with ventricular septal defect, isthmus hypoplasia and descending aortic flow supplied mainly by the ductus. An increase in the arterial partial pressure of oxygen (PO2) was seen in groups 1 and 2. Six patients from group 1 and two from group 2 developed heart failure; cortical hyperostosis of long bones was seen in three patients from group 1 and three from group 2; one from group 1 had refractory diarrhea. Other side effects seen at the beginning improved as the rate of infusion diminished. In group 3, the patient with complex coarctation had a decrease in blood pressure in the arms, an increase in pressure in the legs and restoration of renal function; in the patient with no ventricular septal defect, heart failure worsened during therapy. Histologic changes seen in three ductus were attributed to the closing process. When delaying surgery in selected ill infants with heart defects is deemed advantageous, long-term infusions of prostaglandin E1 are feasible.

Cardiovascular anomalies with imperforate anus.

In 68 patients with anorectal malformations cardiovascular anomalies (CVA) were seen in 15 and genitourinary (GU) anomalies in 30. CVA were more frequent (33%) whenever there was a GU anomaly. Ventricular septal defect was the most frequent lesion. All but 1 CVA occurred with type III anorectal malformation. The complexity of the cardiac lesion did not parallel that of the GU anomaly.