177,209 research outputs found
The role of tunability in microwave amplifier synthesis
No full textThis paper deals with the minimisation of the tunability factor. This represents the input port sensitivity of the amplifier circuit to all parametric load alterations, and acquires importance especially when the design specifications are so strict that no tolerance margin is given for placing of the input and output reflection coefficients. An operative procedure, combining graphical and numerical techniques, is also shown, which allows a simple design of the system parts
Microwave low noise amplifier: A new formulation for single and two-stage design
No full textA new method to get the best value of input reflection coefficient in microwave low noise amplifier design is proposed, with reference to both single and two-stage cases. A simple computer program shows an application example
Epidemiological aspects of isolated systolic hypertension in the elderly population as cerebrovascular risk factor.
No full textA large number of studies indicate that isolated systolic hypertension (ISH) is an important cerebrovascular risk factor. This clinical state is very common in elderly people who are the most exposed to stroke risk. Therefore, it is important to know the real prevalence of ISH, in order to predict the possible incidence of cerebrovascular disease in the elderly population. In the Camerano study on hypertension, we have verified the prevalence of ISH in the elderly. ISH has been considered clinically when the systolic arterial pressure (SAP) was higher than 160 mmHg, and the diastolic arterial pressure (DAP) was lower than 90 mmHg. In our study population, an ISH prevalence of 11.9% was found in the elderly (above 60 years of age); whereas in the adult population (between 30 and 60 years), it amounted only to 4.5%
Tako-Tsubo-Like Syndrome With Atypical Clinical Presentation: Case Report and Literature Review
No full textA 78-year-old woman presented herself at emergency for the appearance of severe dyspnea. An electrocardiogram showed signs of inferior and anterior necrosis, and laboratory tests showed a small increase of myocardial cytonecrosis enzymes. An echocardiogram detected a reduction of global systolic function (ejection fraction [EF] approximately 40%) as well as akinesia of the apex, interventricular septum middle segments, and anterior and anterolateral walls, with basal segments showing compensatory hyperkinesia. The coronarography showed a coronary tree substantially free from significant lesions. The patient was transferred to the cardiology unit of our hospital. Based on the contained increase of the cardiac enzymes, the absence of coronary lesions, and the presence of typical echocardiography alterations, we suspected a Tako-tsubo-like syndrome. On deeper anamnestic investigation, an event of strong emotional stress emerged preceding the hospital admission that confirmed the pathology, even though it is atypical to see clinical presentation a long time after a stressful event
Sexual dimorphism in arterial hypertension: an age-related phenomenon.
No full textEpidemiological, clinical and experimental evidence is available indicating that male subjects develop hypertension with a higher probability than age-matched females. The sexual dimorphism of blood pressure (BP) has been observed both in normotensive and hypertensive subjects. In order to analyze the presence of sexual dimorphism of arterial hypertension (AH) and its relationship to the aging process - particularly to the menopause - the population screened in the Camerano Study has been examined. In addition, to evaluate sex-related differences in the AH, another sample of 3765 patients from our Hypertension Centre has also been considered. Our samples displayed a real cross-over in the prevalence of arterial hypertension, hypercolesterolemia, hyperglycemia and obesity in women versus men, after the menopausal period. In fact, in the adult group (20-54 years) the prevalence of arterial hypertension was significantly higher (P54 years), we observed a significantly higher prevalence (P<0.001) in females (46.6%) than in males (34.7%). These results suggest that the menopause and age can play a separate role in the sexual dimorphism of arterial hypertension. A significant gender-related difference in hypertensive patients was found only in hypercholesterolemia above the age of 50 years, namely, females have this disorder more frequentl
Circulating microRNAs (miRs) for diagnosing acute myocardial infarction: An exciting challenge.
No full textPrevention of cardiovascular events in early menopause: a possible role for hormone replacement therapy
No full textHeart disease is a major cause of illness and death in women. It is well known that there is an increase in cardiovascular disease and
cardiovascular risk factors after the menopause, but it is still unclear whether the change in risk factors after the menopause is only related to the aging process or is principally due to estrogen deprivation. Observational studies suggest a protective role for estrogens, whereas recent randomized controlled trials report a negative effect of oral estrogens on primary and secondary prevention of cardiovascular events.
The role of inflammation in the process of atherogenesis and in determining the cardiovascular disease risk in postmenopausal women has
been focused only recently as well as the role of the estrogen receptor system in different tissues and the role of genetic susceptibility to adverse events during estrogen therapy.
The objective of this work was to review the current understanding of the relationships between cardiovascular disease risk factors and hormonal age-related changes in postmenopausal women and particularly in early and surgical postmenopausal women, for a more appropriate evaluation of the expected effects of therapy with exogenous estrogens in a specific sample of the large population of postmenopausal women
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