Updated Summation Model: An Improved Agreement with the Daya Bay Antineutrino Fluxes.

A new summation method model of the reactor antineutrino energy spectrum is presented. It is updated with the most recent evaluated decay databases and with our total absorption gamma-ray spectroscopy measurements performed during the last decade. For the first time, the spectral measurements from the Daya Bay experiment are compared with the antineutrino energy spectrum computed with the updated summation method without any renormalization. The results exhibit a better agreement than is obtained with the Huber-Mueller model in the 2-5 MeV range, the region that dominates the detected flux. A systematic trend is found in which the antineutrino flux computed with the summation model decreases with the inclusion of more pandemonium-free data. The calculated flux obtained now lies only 1.9% above that detected in the Daya Bay experiment, a value that may be reduced with forthcoming new pandemonium-free data, leaving less room for a reactor anomaly. Eventually, the new predictions of individual antineutrino spectra for the ^{235}U, ^{239}Pu, ^{241}Pu, and ^{238}U are used to compute the dependence of the reactor antineutrino spectral shape on the fission fractions.

Large Impact of the Decay of Niobium Isomers on the Reactor ν[over ¯]_{e} Summation Calculations.

Even mass neutron-rich niobium isotopes are among the principal contributors to the reactor antineutrino energy spectrum. They are also among the most challenging to measure due to the refractory nature of niobium, and because they exhibit isomeric states lying very close in energy. The ß-intensity distributions of ^{100gs,100m}Nb and ^{102gs,102m}Nb ß decays have been determined using the total absorption γ-ray spectroscopy technique. The measurements were performed at the upgraded Ion Guide Isotope Separator On-Line facility at the University of Jyväskylä. Here, the double Penning trap system JYFLTRAP was employed to disentangle the ß decay of the isomeric states. The new data obtained in this challenging measurement have a large impact in antineutrino summation calculations. For the first time the discrepancy between the summation model and the reactor antineutrino measurements in the region of the shape distortion has been reduced.

Total Absorption Spectroscopy Study of (92)Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape.

The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. (92)Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied (92)Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.

Enhanced γ-Ray Emission from Neutron Unbound States Populated in ß Decay.

Total absorption spectroscopy is used to investigate the ß-decay intensity to states above the neutron separation energy followed by γ-ray emission in (87,88)Br and (94)Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy is compared to Hauser-Feshbach model calculations. For (87)Br and (88)Br the γ branching reaches 57% and 20%, respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich (94)Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled by introducing an enhancement of 1 order of magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proves to be correct, leads to a similar increase in the (n,γ) cross section that would have an impact on r process abundance calculations.

New antineutrino energy spectra predictions from the summation of beta decay branches of the fission products.

In this Letter, we study the impact of the inclusion of the recently measured beta decay properties of the (102;104;105;106;107)Tc, (105)Mo, and (101)Nb nuclei in an updated calculation of the antineutrino energy spectra of the four fissible isotopes (235,238)U and (239,241)Pu. These actinides are the main contributors to the fission processes in pressurized water reactors. The beta feeding probabilities of the above-mentioned Tc, Mo, and Nb isotopes have been found to play a major role in the γ component of the decay heat of (239)Pu, solving a large part of the γ discrepancy in the 4-3000 s range. They have been measured by using the total absorption technique, insensitive to the pandemonium effect. The calculations are performed by using the information available nowadays in the nuclear databases, summing all the contributions of the beta decay branches of the fission products. Our results provide a new prediction of the antineutrino energy spectra of (235)U, (239,241)Pu, and, in particular, (238)U for which no measurement has been published yet. We conclude that new total absorption technique measurements are mandatory to improve the reliability of the predicted spectra.

Reactor decay heat in 239Pu: solving the γ discrepancy in the 4-3000-s cooling period.

The ß feeding probability of (102,104,105,106,107)Tc, 105Mo, and 101Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for 239Pu in the 4-3000 s range.

Deformation of the N=Z nucleus 76Sr using beta-decay studies.

A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of quasi-random-phase approximation calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large total absorption gamma spectrometer, "Lucrecia," newly installed at CERN-ISOLDE.

Radionuclide ventriculography in dynamic cardiomyoplasty.

Dynamic cardiomyoplasty improves ventricular function by increasing pump function and by limiting cardiac dilatation. The aim of this study was to assess long-term myocardial performance by radionuclide ventriculography on dilated cardiomyopathy patients subjected to cardiomyoplasty. Thirteen survivors were included. Radionuclide ventriculography was performed one week before surgery and one year later. Five patients were also studied two years following surgery. The left ventricular ejection fraction (LVEF), end-diastolic volume (EDV) and ventricular amplitude ratio (VAR) to assess mitral regurgitation were measured. Every case after one year showed a non-significant increase in LVEF. However, the decrease in EDV and in VAR was significant (p < 0.01). No significant difference in these values was found after two years. We conclude that the effects of cardiomyoplasty--reduction of cardiac dilatation, wall stress and mitral regurgitation--are more evident during the first year after surgery. Thereafter, a certain stabilization is observed.

[Experience with the use of an implantable automatic cardioverter defibrillator]. / Experiencia en el uso del desfibrilador cardioverter automático implantable.

An automatic implantable cardioverter-defibrillator with pacemaker was implanted in Cuba, in ten patients with malignant ventricular arrhythmias, sudden cardiac collapse, and ventricular tachycardia with syncope, after a previous electrophysiological study for analysis of the arrhythmia and pharmacological evaluation. The patients were 9 males, ranging in age from 23 a 70 years, with a mean of 48 years, and an ejection fraction of 32% (18-62%). The etiologies were: an old myocardial infarction (7 cases) and dilated cardiomyopathy (3 cases). During the follow-up, mean from 2 to 25 months, four patients received effective shocks for rapid palpitations and presyncope. Two patients died, one due to incessant ventricular tachycardia and one of a cause unrelated to device. We concluded that the GUARDIAN 4201 and 4202 device are useful to prevent sudden cardiac death in high risk patients who experienced a life threatening arrhythmia.

[Surgery for Wolff-Parkinson-White syndrome. Cuban experience]. / Cirugía en el síndrome de Wolff Parkinson White. Experiencia cubana.

Surgery is a recent approach in the treatment of arrhythmias. The first successful surgery of this type was the interruption of the accessory pathway in a patient suffering from the Wolff Parkinson White syndrome. In 25 consecutive patients who underwent surgery, 28 accessory AV pathways were identified with classical endocardial and epicardial mapping. Only three patients experienced recurrence of preexcitation without symptoms; one patient had AV block; and another patient died. In all cases we successfully used either an endocardial or an epicardial approach. The purpose of this paper is to report the Cuban experience with this procedure.

Dehydrobenzperidol and disopyramide in A-V conduction.

The effects on A-V conduction of dehydrobenzperidol (Droperidol) 0.35 and 1.0 mg/kg i.v.) and disopyramide (1, 5 and 10 mg/kg i.v.) were tested in anesthetized, open chest and paced dogs. His's bundle electrograms were recorded by means of a catheter electrode or by a sutured electrode-bearing plaque in the A-V nodal region. Droperidol at the lower dose did not modify conduction time, while 1.0 mg/kg (3 times the usual clinical dose), prolonged atrial-His conduction without modifying H-V interval. Disopyramide 1 mg/kg caused a non-significant decrease in atrial-His concuction time, while in doses of 5 and 10 mg/kg it prolonged both conduction times (S-H and H-V), due to a predominant direct depressant effect, which is opposite to the atropinic actions of the drug.

Traumatismos cardíacos: Presentación de 24 casos / Cardiac traumatism. A report of 24 cases

Se informa la experiencia obtenida en el Instituto de Cardiología y Cirugía Cardiovascular en 24 pacientes que presentaban diversos tipos de traumatismos cardíacos; de éstos, 9 fueron operados de urgencia. Se encontró una frecuencia de 0,68 porciento para perforaciones cardíacas ocurridas en nuestro medio en el transcurso de un cateterismo cardíaco. El riesgo de la perforación fue mayor, tanto desde el punto de vista de la gravedad como de la frecuencia, en los cateterismos del lado izquierdo del corazón. Se discute el diagnóstico y la conducta a seguir frente a estos casos según los síntomas iniciales y el origen de la perforación, basándose en la evolución obtenidas en nuestros casos y en una revisión de la literatura al respecto, llegándose a la conclusión de uqe las perforaciones de las cavidades izquierdas deben ser abordadas quirúrgicamente de emergencia, sin ninguna demora, y que solamente se dará un margen de espera bajo vigilancia estrecha a las perforaciones de las cavidades cardíacas derechas (AU)