In many applications of structural engineering, the following question arises: given a set of forces , , …, applied at prescribed points , , …, , under what constraints on the forces does there exist a truss structure (or wire web) with all elements under tension that supports these forces? Here we provide answer to such a question for any configuration of the terminal points , , …, in the two- and three-dimensional cases. Specifically, the existence of a web is guaranteed by a necessary and sufficient condition on the loading which corresponds to a finite dimensional linear programming problem. In two dimensions, we show that any such web can be replaced by one in which there are at most elementary loops, where elementary means that the loop cannot be subdivided into subloops, and where is the number of forces , , …, applied at points strictly within the convex hull of , , …, .
View Article and Find Full Text PDFField patterns occur in space-time microstructures such that a disturbance propagating along a characteristic line does not evolve into a cascade of disturbances, but rather concentrates on a pattern of characteristic lines. This pattern is the field pattern. In one spatial direction plus time, the field patterns occur when the slope of the characteristics is, in a sense, commensurate with the space-time microstructure.
View Article and Find Full Text PDFWith regard to health care workers the irritative contact dermatitis represents about the 80% of all the dermopathies in sanitary staff whereas the allergic contact dermatitis covers approximately the 20% of the professional dermatoses. In our study 4 cases of allergy to latex in hospital nurses are presented; the clinical history is described for each of them as well as the resulting judgment of suitability to the specific work. In general population the allergy to latex is estimated to be approximately 1-6%; in sanitary staff it rises to 5-12%.
View Article and Find Full Text PDFDiabetes mellitus is a disease of great social relief that has a deep impact also in working life. Our short paper wants to highlight some critical aspects that occupational physician must deal with both in preventive and periodic health evaluation for diabetic subjects. In our study, performed on health care workers, we reported 16 cases of diabetes; 10 of them were nurses, 5 sanitary auxiliaries and 1 sanitary technical operator.
View Article and Find Full Text PDFBackground: The effects of long-term treatment with gallopamil 50 mg t.i.d were assessed in 8 patients, 7 males and 1 female, aged 47-69 years, with stable angina pectoris, positive exercise tests, coronary artery disease and no previous myocardial infarction.
View Article and Find Full Text PDFNeuropsychological impairment and the subjective symptoms of 21 patients with organic solvent intoxication were compared with those of patients with vertebrobasilar insufficiency (n = 16), cerebral trauma (n = 16), and headache (n = 15). The aim was to study the diagnostic efficiency of psychological methods in the neuropsychological assessment of patients with suspected solvent intoxications. Our results suggest that it is possible to differentiate between the four groups at group level; however, because of the variance in each group, no specific rule for individual diagnostics can be given.
View Article and Find Full Text PDFPreliminary clinical studies with 131I-meta-iodobenzylguanidine, a newly synthesized radiopharmaceutical and guanethidine analog capable of imaging the adrenal medulla, have led to the identification of a case of disseminated malignant pheochromocytoma with the localization of brain and bone metastases. The result is of particular interest as the symptomatology in this case appeared rather equivocal and various investigations had led to a completely different diagnosis. This new scintigraphic technique has proved to be safe, specific and noninvasive, and it may have a clinical application as a complementary or alternative technique to conventional diagnostic tests.
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