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R Jauregui

Publications and source records attributed to R Jauregui.

6 recordsLinked to original sources
PubMed2000

Mie scattering and the physical mechanisms of sonoluminescence

We propose an experimental procedure to investigate possible mechanisms for radiation emission in sonoluminescence. Our analysis is based on Mie's theory of light scattering for a coated sphere in an external medium. Depending on the physical mechanism responsible of sonoluminescence, the dielectric constant of the hot spot changes. As a case study we consider the problem of the detection of an inner plasma core in sonoluminescent bubbles. Our results show that polarization measurements of scattered light should discern the presence of a plasma provided that light detectors are fast enough. Extensions to other emission mechanisms are briefly discussed.

Journal Article↗
PubMed1977

Upper airway obstruction in euthyroid goiter.

Although it is recognized that an enlarged thyroid may occasionally cause tracheal compression, the incidence in euthyroid goiter is unknown. Twenty patients with nontoxic goiter were investigated for upper airway obstruction. Although none of them had dyspnea as a chief complaint, on direct questioning 9/20 had a history of shortness of breath on exertion and choking sensation. Upper airway obstruction was detected in 7/20 (35%) by roentgenography, 12/20 (60%) by flow volume loop (FVL), and in 16/20 (80%) by combined roentgenography and FVL. After therapy for goiter, there was a reduction in the size of the goiter and an improvement in FVL in the whole group. The statistically significant change occurred in peak expiratory flow (P less than .01) and peak inspiratory flow (P less than .05). These findings and the change in configuration of the curve suggested less upper airway compression. We conclude that goiter often causes unsuspected upper airway obstruction, usually slow in onset and not noticed by the patient.

Adult↗
PubMedDate not supplied

Percutaneous transluminal ultrasonic angioplasty: preliminary clinical report of ultrasound plaque ablation in totally occluded peripheral arteries.

Peripheral arterial obstructive disease has been treated with ultrasound ablation. Thirty two patients (pts), mean age 67 +/- 10 years underwent angiosonoplasty, with a prototype ultrasonic system, due to severe claudication (31%), rest pain (44%), rest pain and ulceration (25%). Angiosonoplasty was successful in 26/32 (81%) stenoses, (1/2 iliac, 9/2 femorals, 11/12 popliteal, 5/6 tibial). Angiography before and after angiosonoplasty confirmed that the lesions were successfully opened, (81%, p less than 0.05). A mean of 3 +/- 2 passes were required to adequately remove sufficient plaque. Balloon angioplasty was used in combination with angiosonoplasty in 11/32 (34%) occluded vessels. Complications included groin hematoma in 4 pts (12%) and vascular spasm in two patients (6%). Within 24 hours, 27/32 (94%) pts were discharged clinically improved. Reocclusion occurred in 4 pts (12%) immediately after the procedure. Ankle brachial indices significantly increased from 0.52 +/- 0.10 before to 0.70 +/- 0.12 after (p less than 0.05). In conclusion, the use of ultrasound energy to ablate atherosclerotic plaque would appear safe, and has shown no restenosis and a low incidence of complications over a six month period.

Aged↗
PubMedDate not supplied

[X syndrome. Angiographic findings].

Coronary artery spasm is the most frequent cause of ischemic heart disease without coronary atherosclerosis once other causes such as cardiomyopathy, arteritis, coronary ectasia, valvular heart disease or hypertensive heart disease are eliminated. We report 23 patients, 15 males and 8 females, whose ages ranged from 34 to 63 years, with a mean age of 47 years, with demonstrated angina pectoris and myocardial ischemia, whose cardiac cineangiography showed no signs of atherosclerosis. Nevertheless, a significant retardation in the progression speed of the contrast medium was observed, as indirect evidence of the increment in coronary resistance at the arteriole level. Coronary spasm was ruled out by administration of intracoronary ergonovine, and other causes of myocardial ischemia, such as muscular bridges, were also discarded. The clinical presentation of the ischemic heart disease was unstable angina (UA) in 21 patients and myocardial infarction (MI) in 2. In the UA group, 14 patients showed ischemic changes in the ECG while the pain lasted, and in 8 patients the changes were present during the stress test. In all of them, the stress test perfusion scan with thallium 201 showed myocardial ischemia. In the IM group, the diagnosis was based on the clinical findings, the ECG, the enzyme curve, and the technetium 99 cardiac scintigram. In the two-year follow-up the prognosis has been favorable with treatment based on calcium antagonists. Nowadays 18 patients are asymptomatic, four have stable angina and only one has unstable angina.

Adult↗
PubMedDate not supplied

[Sudden death caused by 2-directional tachycardia in an adolescent].

The history of a 12 year old male, who developed a bidirectional tachycardia and sudden death without evidence of neurological or cardiac disease is described. The role of bidirectional tachycardia related to sudden death is discussed, as well as its possible origin and mechanisms, based on the case described.

Child↗