The classic endoscopic diagnosis of a Barrett's esophagus (BE) is based on the finding of > or =3 cm, of distal esophagus covered by specialized columnar epithelium. However, currently, it is based on the finding of intestinal metaplasia (IM) at the squamous-columnar mucosal junction, independent of its extent. The aim of this study was to determine the prevalence of Barrett's esophagus by endoscopic and histological findings in control subjects and in patients with symptoms of gastroesophageal reflux (GER). Three hundred and six control subjects and 376 patients with symptoms of gastroesophageal reflux were included in this prospective study. Patients with Barrett's esophagus were classified in three groups as follows. 1. Intestinal metaplasia at the cardia. When endoscopy showed non-Barrett's esophagus, but histological intestinal metaplasia was found. 2. Short-segment Barrett's esophagus. When <3 cm, was covered with tongues or finger-like or creeping substitution of distal esophagus. 3. Long-segment Barrett's esophagus. When > 3 cm, of distal esophagus was covered by specialized columnar epithelium. Two biopsies at the antrum, four biopsies at the squamous-columnar junction and one or two at the distal esophagus were taken. In control subjects, 1.6% showed histological IM at the esophagogastric junction. In patients with GER without esophagitis or with erosive esophagitis, IM was found in 18% and 10.7% respectively. 'Short-segment' Barrett's esophagus was three times more frequent than 'long-segment' Barrett's esophagus. Patients with Barrett's esophagus were significantly older than the other groups. The presence of complications or erosions, peptic ulcer or stricture were significantly more frequent among patients with 'long-segment' Barrett's esophagus (p < 0.0001). The prevalence of dysplasia was similar in all groups of patients with Barrett's esophagus. Complications such as ulcers, stricture and dysplasia were exclusively seen among patients with BE, whereas non-Barrett's patients did not exhibit these complications. In control subjects, IM can be found in a low percentage of cases. Among patients with symptoms of GER, the classic endoscopic diagnosis of a Barrett's esophagus can underestimate this condition in 80% of the cases. Patients with intestinal metaplasia at the cardia already present 17% of the cases with low-grade dysplasia. In all patients with symptoms of GER, systematic biopsies at the squamous-columnar junction should be taken.

Abstract-This paper is aimed at studying the electromagnetic radiation pattern of a multipactor discharge occurring in a parallel-plate waveguide. The proposed method is based on the Fourier expansion of the multipactor current in terms of timeharmonic currents radiating in the parallel-plate region. Classical radiation theory combined with the frequency domain Green's function of the problem allows the calculation of both the electric and the magnetic radiated fields. A novel analytical formula for the total radiated power of each multipactor harmonic has been derived. This formula is suitable for predicting multipactor with the third-harmonic technique. The proposed formulation has been successfully tested with a particle-in-cell code.Index Terms-Microwave discharges, multipactor effect, parallel-plate waveguide, radiated power, third-harmonic detection technique.

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Multipactoring is a non-linear phenomenon that appears in high-power microwave equipment operating under vacuum conditions and causes several undesirable effects. In this paper, a theoretical and experimental study of the RF spectrum radiated by a multipactor discharge, occurring within a realistic microwave component based on rectangular waveguides, is reported. The electromagnetic coupling of a multipactor current to the fundamental propagative mode of a uniform waveguide has been analysed in the context of the microwave network theory. The discharge produced under a single-carrier RF voltage regime has been approached as a shunt current source exciting such a mode in a transmission-line gap region. By means of a simple equivalent circuit, this model allows prediction of the harmonics generated by the discharge occurring in a realistic passive waveguide component. Power spectrum radiated by a third-order multipactor discharge has been measured in an E-plane silver-plated waveguide transformer, thus validating qualitatively the presented theory to simulate the noise generated by a single-carrier multipactor discharge.

Clozapine is an atypical antipsychotic used in refractory schizophrenia and depression. Its use is often complicated by its vast side-effect profile including cardiovascular reactions, agranulocytosis, and seizures. Specifically, the cardiac complications of clozapine have been shown to predominantly cause myocarditis and pericarditis. In this case report, the case of a 58-year-old male being treated for treatment-resistant depression and schizophrenia who suffers from tachycardia is presented. He is treated empirically for orthostatic hypotension with IV fluids without much success. Further imaging and echocardiography demonstrated a pericardial effusion, a rare reaction (≤1 : 10000) that has only been documented in a handful of case reports. This anecdotal evidence highlights the significance of polyserositis/pericardial effusion in the context of clozapine-induced orthostatic hypotension resistant to rehydration. When starting a patient on clozapine, it is important to consider further workup and monitoring with laboratory baseline biomarkers and cardiac evaluation with symptomatic individuals. Upon immediate cessation of clozapine, the pericardial effusion should spontaneously resolve without complication and should not be rechallenged.