Dramatic Plasmon Response to the Charge-Density-Wave Gap Development in 1T-TiSe_{2}.

1T-TiSe_{2} is one of the most studied charge density wave (CDW) systems, not only because of its peculiar properties related to the CDW transition, but also due to its status as a promising candidate of exciton insulator signaled by the proposed plasmon softening at the CDW wave vector. Using high-resolution electron energy loss spectroscopy, we report a systematic study of the temperature-dependent plasmon behaviors of 1T-TiSe_{2}. We unambiguously resolve the plasmon from phonon modes, revealing the existence of Landau damping to the plasmon at finite momentums, which does not support the plasmon softening picture for exciton condensation. Moreover, we discover that the plasmon lifetime at zero momentum responds dramatically to the band gap evolution associated with the CDW transition. The interband transitions near the Fermi energy in the normal phase are demonstrated to serve as a strong damping channel of plasmons, while such a channel in the CDW phase is suppressed due to the CDW gap opening, which results in the dramatic tunability of the plasmon in semimetals or small-gap semiconductors.

Tratamiento no farmacológico del insomnio. 3o parte / Non pharmacological treatment of insommia. 3o parte

Los trastornos del sueño son una patología frecuente. Cerca del 35 por ciento de los colombianos presentara en cualquier momento de su vida una alteración del sueño. El insomnio es la queja principal en adultos y ancianos. La prevalencia del insomnio en mujeres es del 40 por ciento, se presenta en 30 por ciento de los hombres y en 50 por ciento de personas mayores de 65 años. Los factores asociados con mayor prevalencia son género femenino, presencia de trastornos mentales, condiciones médicas generales, abuso de sustancias y edad avanzada. Una adecuada intervención exige el diagnóstico cuidadoso y el tratamiento según la causa. Existe relación directa entre insomnio y alteraciones médicas, neurológicas, neumológicas y psiquiátricas. El omnólogo descarta estas patologías cuando examina un paciente mediante la anamnesis, heteroanamnesis, examen físico, agenda de sueño, exámenes somáticos y psicológicos y en ocasiones la polisomnografía. Para su manejo se evalúan factores predisponentes, precipitantes y perpetuadores que afectan el curso del insomnio. El tratamiento actual considera un abordaje integral y edológico. Se usa higiene del sueño, hipnóticos, CPAP-BiPAP-AutoCPAP, luminoterapia, cronoterapia y en ocasiones la melatonina. En este artículo se presenta el manejo no psicofarmacológico del insomnio crónico. Se describen las principales técnicas comportamentales y su aplicación en el tratamiento de estos pacientes

Menopausia: actitudes y conocimientos en un grupo de medicos internos, de la facultad de medicina, de la Universidad de Antioquia / Menopause: attiude an knowledge in a group of final-year medical students of the school of medicine of the University of Antioquia

Se presentan los resultados de una encuesta realizada a los médicos de la Facultad de Medicina de la Universidad de Antioquia, en el segundo semestre de 1997. El proyecto se realizó con el doble propósito de construir conocimiento sobre el tema del climaterio femenino y, en segundo lugar, para aportar elementos pertinentes a la discusión de cambio curricular en que está empeñada la Facultad y la Universidad. Partimos de la hipótesis de que la historia personal del individuo limita las actitudes y condiciona el desarrollo de motivación y destrezas sobre un tema determinado. Se utilizó el censo y las técnicas de encuesta y escala Lickert para indagar sobre variables socioculturales, demográficas y de carácter científico/técnico. Se encontró que el nivel de conocimientos, medido por la nota, fue de 2.85 + 0.83; la actitud frente a la terapia fue baja en el 44 por ciento y alta en el 40 por ciento. Como se había previsto en la hipótesis, la relación entre actitudes y conocimientos fue directa, pero la asociación con variables sociodemográficas no pudo determinarse debido a la homogenidad de la población

[Barrett++ esophagus in children. Presentation of 12 cases]. / Esófago de Barrett en niños. Presentación de doce casos.

This paper describes 12 cases of Barrett's oesophagus selected out of a population of 364 refluxing children studied from 1986 to 1990. Their mean age was 14, seven were cared for in special institutions for brain damaged and 2 had been operated upon for oesophageal atresia at birth. Excessive acid exposure was documented in 8/10 patient studied and simultaneous gastric and oesophageal pH-monitoring demonstrated massive duodeno-gastric alkaline reflux in 3. Histological studies revealed that columnar-lined epithelium was of fundic type in 2 cases, of junctional type in 7 and of specialized type in three. Helicobacter pylori was found in the mucosa of 8 patients. The present series confirms that BE should be looked for endoscopically in children with GER and provides further evidence of the long duration of GER disease and the excessive acid-alkaline chemical exposure of the oesophageal lining in the pathogenesis of mucosal changes.

Making it on the streets in Bogotá: a psychosocial study of street youth.

In this study, we investigated the perceptions of the life situations, experiences, psychosocial characteristics, and environments of 94 street youth in Bogotá, Columbia. We outlined the implications of our results for developmental theory, psychosocial competence theory, future research, public policy formation, program development, and direct intervention.

Biperiden administration in normal sleep and after rapid eye movement sleep deprivation in healthy volunteers.

Twenty-six healthy volunteers were randomly assigned to one of four groups. Groups Bip-4 and Bip-6, each with six subjects, received 4 and 6 mg of biperiden, respectively, and were studied on acclimatization, baseline, biperiden, and follow-up nights. Group REM-P (n = 7) and Group REM-Bip (n = 7) were studied on acclimatization, baseline, six nights of REM sleep deprivation, and one recovery (treatment) night with either placebo (group REM-P) or biperiden (group REM-Bip), and one follow-up night. Biperiden 4 and 6 mg increased REM sleep latency and biperiden 6 mg reduced REM sleep time. On the recovery night following REM sleep deprivation Group REM-P and REM-Bip showed an increase in sleep continuity. REM sleep time in the REM-P group was increased during the recovery (treatment) night (REM sleep recovery), while the REM-Bip group did not show a significant REM sleep increase during recovery (treatment) night. It was not until the follow-up night that REM sleep increased in the REM-Bip group.

Ultrasound study of acute appendicitis in children with emphasis upon the diagnosis of retrocecal appendicitis.

Acute appendicitis in children frequently presents equivocal clinical manifestations. Delay of the proper diagnosis and unnecessary laparotomies are common. Abdominal ultrasound has proved to be useful in the diagnosis of acute appendicitis in adults. We have performed a preoperative ultrasound study in 368 children with acute appendicitis. Among the, 92 had a retrocecal appendicitis. Ultrasound established the correct diagnosis in 92.6% of patients, and in 94.5% of those with a retrocecal appendicitis. At our institution an abdominal sonography is performed on any child with a doubtful clinical diagnosis of acute appendicitis, helping the surgeon to take the decision to perform a laparotomy.

[New aspects of gallbladder pathology in children]. / Nuevos aspectos de la patologia de la vesicula biliar en niños.

We have reviewed in a retrospective study 38 children treated in our Hospital, during the last seven years, because of non congenital gall-bladder disease. The diagnosis established were cholelithiasis 58 for 100, hydrops 26 for 100, acalculous cholecystitis 13 for 100 and hemobilia in one child. Cholelithiasis was more frequent in females at a rate of 2/1. Just the opposite incidence was found for acalculous gall-bladder pathology. Mean age at time of first hospitalization was 7.6 years for the cholelithiasis group and 6.6 years for the rest. Symptoms in order of frequency were abdominal pain, vomiting and fever. Abdominal sonography has been basic in establishing to correct diagnosis in practically all cases. Our most interesting finding has been the clinical manifestations of patients with "Hydrops", consisting of abdominal pain which disappears spontaneously after 24 to 48 hours. The diagnosis has been established only after performing abdominal sonographic studies in children with abdominal pain of unclear etiology.

[Modified Kasai technique for the treatment of biliary atresia]. / Una modificación de la técnica de Kasai para el tratamiento de la atresia biliar.

Kasai's procedure has changed significantly the prognosis of biliary atresia. However, ascending cholangitis is a relatively frequent postoperative complication with high morbidity and mortality rates. We have developed a modification of that technic consisting in the isolation of a segment of jejunum-with its blood supply carefully preserved, after fashioning an antireflux valve in its distal end. This segment of bowel, less than 10 cm. in length, is anastomosed to the porta hepatis proximally and to the duodenum distally. Using this technic, we have operated upon three infants with biliary atresia and a child with extended rabdosarcoma of the biliary tree. After a follow up of 10 to 17 months with an average of 12.5 months, all children remain free of cholangitis and two of them are anicteric.

[Tendon and/or nerve lesions of the hand in childhood]. / Lesiones tendinosas y/o nerviosas de la mano en la infancia.

We have reviewed 50 consecutive children treated during the last five years of injuries of nerves and tendons of the hand, wrist and forearm. Seventy six per cent of these injuries affected the hand and/or fingers. The rest were located in the wrist or forearm.