Showing papers by "University of Milan published in 1981"
TL;DR: In this paper, a general condition for high-frequency synthesis applicability is given, together with a method which allows direct converter design from the desired input-output characterizations, and a general model is introduced for highfrequency synthesis converters.
Abstract: This paper deals, both from the Fourier analysis and the circuit design point of view, with a large family of electronic power converters which synthesize the assigned slow-varying waveforms via highfrequency switching, thereby needing very little reactive elements. A general condition for high-frequency synthesis applicability is given, together with a method which allows direct converter design from the desired input-output characterizations. Furthermore, a general model is introduced for high-frequency synthesis converters; as a consequence, they are characterized as two-port, multipole, time varying, linear circuit elements. Finally, as a major application example, a new AC-AC, three-to-three phase converter is introduced. The new converter displays several attractive features: sinusoidal waveforms, bidirectionality, separate control over amplitude, frequency, phase, and power factor. Moreover, depending on which side is taken as an input, it can either step up or step down the voltage. For these reasons the new converter can be regarded to as a generalized transformer.
404 citations
TL;DR: It is shown that the consistency of the VIII:C response tends to decrease when repeated doses are given to healthy subjects, and this study shows that the response appears to be more prolonged in haemophiliacs.
Abstract: Summary. These studies were designed with the purpose of providing clinico-pharmacological information relevant to the use of DDAVP in the management of mild haemophilia and von Willebrand's disease (VWD). In healthy subjects, intravenous DDAVP produced its maximal response at a dose of 0.3 μg/kg. The extent of the increase in factor VIII coagulant activity (VIII:C) and factor VIII related antigen (VIIIR:Ag) induced by this dose was not significantly different from that observed with the same dose in haemophiliacs and VWD patients. In these, the bleeding time was not shortened. DDAVP given intranasally was followed by a two-fold increase of VIII:C. This route of administration might be adopted to provide an emergency aid in bleeding patients and to yield higher VIII:C levels in blood donors. In healthy subjects, the half-disappearance time of autologous VIII:C after increase induced by i.v. DDAVP is similar to that observed in patients with VWD treated in the same conditions, whereas the response appears to be more prolonged in haemophiliacs. This study shows that the consistency of the VIII:C response tends to decrease when repeated doses are given to healthy subjects. Repeatedly-treated haemophiliacs and VWD patients showed varied patterns, ranging from no change of the response to its early abolishment.
287 citations
TL;DR: It is suggested that the left half of the spatial framework of visual representations is impaired in patients with contralateral neglect, and analogical brain processes seem to underlie these representations.
234 citations
TL;DR: In this article, an unusual stratigraphic unit (nicknamed "homogenite") fills topographic lows in the complex ridge and trough bathymetry at two survey sites on the Western Mediterranean Ridge and the Calabrian Ridge.
Abstract: An unusual stratigraphic unit (nicknamed “homogenite”) fills topographic lows in the complex ridge and trough bathymetry at two survey sites on the Western Mediterranean Ridge and the Calabrian Ridge. On near-bottom 4-kHz seismic-reflection profiles, this unit us an acoustically transparent, near-surface, flat-lying layer, whereas in cores, it is a homogeneous gray marl as much as 7 m thick. Grain size decreases upcore within the unit, implying that it was deposited in a single event controlled by gravitational settling. The stratigraphic position of the homogenite relative to a firmly dated sapropel bed suggests emplacement between 4400 and 3100 yr B.P. The source of the homogenite is inferred to be the nearby basin walls. Farther east, two other sites with similar rugged topography lack homogenite entirely.
A triggering mechanism is required which is capable of initiating massive sediment transport simultaneously in many separate basins at the western two survey sites, but which is not effective at the eastern sites. A large archeologically recorded earthquake of the correct age is considered and rejected because its epicenter is closer to the nonhomogenite-bearing sites than to the sites where this sediment type was observed, and because several other earthquakes of comparable magnitude have since been recorded in the area, whereas the homogenite is unique. The 3,500 yr B.P. collapse of the caldera of the volcano of Santorini caused a huge tsunami which is recorded archeologically and geologically around the eastern Mediterranean. Because of refraction of the tsunami by the bathymetry, and because the caldera collapsed in its southwest corner, a disproportionate amount of tsunami energy was directed toward the western area where homogenite is observed. In contrast, the homogenite-free sites were relatively sheltered. An order-of-magnitude calculation shows that the near-bottom oscillating currents accompanying the Santorini tsunami were at or above the threshold erosion velocity at the homogenite-bearing sites. In addition, the near-bottom pressure pulse under the tsunami at the homogenite-bearing sites was sufficient to cause liquefaction of sediments. Neither mechanism was adequate to cause sediment transport or slope failure at the homogenite-free sites.
215 citations
TL;DR: It is suggested that the ganglioside activation of (Na+ ‐K+)‐ATPase is a specific phenomenon not related to the amphiphilic and ionic properties ofgangliosides, but due to modifications of the membrane lipid environment surrounding the enzyme.
Abstract: GM1 ganglioside binding to the crude mitochondrial fraction of rat brain and its effect on (Na+, K+)-ATPase were studied, the following results being obtained: (a) the binding process followed a biphasic kinetics with a break at 50 nM-GM1; GM1 at concentrations below the break was stably associated, while over the break it was loosely associated; (b) stably bound GM1 activated (Na+, K+)-ATPase up to a maximum of 43%; (c) the activation was dependent upon the amount of bound GM1 and was highest at the critical concentration of 20 pmol bound GM1 X mg protein-1; (d) loosely bound GM1 suppressed the activating effect on (Na+, K+)-ATPase elicited by firmly bound GM1; (e) GM1-activated (Na+, K+)-ATPase had the same pH optimum and apparent Km (for ATP) as normal (Na+, K+)-ATPase but a greater apparent Vmax; (f) under identical binding conditions (2 h, 37 degrees C, with 40 nM substance) all tested gangliosides (GM1, GD1a, GD1b, GT1b) activated (Na+, K+)-ATPase (from 26-43%); NeuNAc, sodium dodecylsulphate, sulphatide and cerebroside had only a very slight effect. It is suggested that the ganglioside activation of (Na+-K+)-ATPase is a specific phenomenon not related to the amphiphilic and ionic properties of gangliosides, but due to modifications of the membrane lipid environment surrounding the enzyme.
212 citations
TL;DR: The dominance of volcanic processes and the importance of vertical tectonics in the geological evolution of the Pacific Basin has been recognised since the time of Charles Darwin this article, and data gathered on several legs of Deep Sea Drilling Project (DSDP) and numerous marine expeditions in the past decade have confirmed Menard's postulate that the Pacific basin was the scene of volcanism on an enormous scale in Mesozoic time.
204 citations
TL;DR: In this article, a list of proteins with known isoelectric points (pl) as determined by focusing are tabulated and the native molecular weight and the submit molecular weight, and stoichiometry are reported.
170 citations
TL;DR: A new gel matrix is described: a highly cross-linked N,N'-(1,2-dihydroxyethylene)bisacrylamide gel, which is hydrophilic, highly porous and can be conveniently used for electrophoresis in horizontal, ultrathin layers cast on silanized glass surfaces.
166 citations
TL;DR: The prognosis for Stage I melanoma of the skin was evaluated on the basis of histologic characteristics of 699 primary tumors collected by the W.H.O. Melanoma Group and it was found that the “intermediate prognosis” group cannot be divided into subgroups with different survival.
Abstract: The prognosis for Stage I melanoma of the skin was evaluated on the basis of histologic characteristics of 699 primary tumors collected by the W.H.O. Melanoma Group from September 1967 to September 1975. Variables considered were maximum tumor thickness, levels of invasion, histologic type, number of mitoses, cell type, growth pattern, inflammatory reaction, angioinvasion, ulceration. When considered as single factors, these criteria, but cell type and inflammatory reaction, significantly affected survival (P < 0.05). However, when each criterion was adjusted by maximum tumor thickness, the number of mitoses and ulceration only were found to be still significant. The type of cells, which is not significant by itself (P = 0.92), becomes significant (P = 0.02) when adjusted by maximum thickness. The most important prognostic factor was maximum tumor thickness (P = 10−9). Using this criterion this series was divided into three groups: (1) “good prognosis” with maximum thickness not exceeding 2 mm and a five-year survival rate of over 80%; (2) “intermediate prognosis” with maximum thickness between 2.01–4.00 mm and a five-year survival rate between 50 and 80%; (3) “poor prognosis” with maximum thickness greater than 4.01 mm and five-year survival rate of under 50%. All other prognostic criteria were evaluated within each group and it was found that the “intermediate prognosis” group cannot be divided into subgroups with different survival. The best survival was observed in patients with primary tumor not thicker than 2.00 mm with no ulceration (P = 0.01) or with spindle cells (P = 0.03); the worse survival was observed in patients with primary melanoma thicker than 4 with ulceration (P = 0.04) or with more than one mitosis per high power field (P = 0.04).
157 citations
TL;DR: It is suggested that gangliosides cause strong side-side head group interactions on the bilayer surface--betweenganglioside oligosaccharide chains and between gangliosiside and phosphatidylcholine polar portions--which lead the lipid chains to assembly in a more rigid fashion.
118 citations
TL;DR: The seed globulins of Lupinus albus were extracted and 12 ditterent proteins were separated: four of them correspond to vicilins and two to legumin.
TL;DR: The results obtained with this experimental model indicate that the ventricular endings of these afferent sympathetic unmyelinated fibers act as "polymodal" receptors, hypothesizing that the peripheral mechanism for cardiac nociception involves intensive excitation of fibers discharging spontaneously and not recruitment of silent fibers which are purely nocICEptive in function.
Abstract: In anesthetized and artificially ventilated cats, we recorded the impulse activity of 23 afferent sympathetic unmyelinated fibers with left ventricular endings, dissected from the left sympathetic rami T3 and T4. All fibers displayed a spontaneous discharge at a rate of 0.79 +/- 0.2 (mean +/- SE) impulses/sec. During constriction of the thoracic aorta, the discharge increased to 1.92 +/- 0.2 impulses/sec. During myocardial ischemia, produced by interruption of left main coronary artery perfusion, supplied through an extracorporeal pump, the impulse activity increased to 1.73 +/- 0.3 impulses/sec. The mean latency for this excitation was 16.5 +/- 1.5 sec. The intracoronary administration of bradykinin (5 and 10 ng/kg) elicited a marked increase in impulse activity that, following 5 ng/kg, reached 2.06 +/- 0.2 impulses/sec, after a latency of 18 +/- 2 sec and in absence of significant hemodynamic changes. Myocardial ischemia and bradykinin never revealed the existence of silent afferent fibers included in the split nerve strand. The results obtained with this experimental model indicate that the ventricular endings of these afferent sympathetic unmyelinated fibers act as "polymodal" receptors. We hypothesize that the peripheral mechanism for cardiac nociception involves intensive excitation of fibers discharging spontaneously and not recruitment of silent fibers which are purely nociceptive in function.
TL;DR: In this article, a new structural model for highly cross-linked polyacrylamide gels is proposed, based on which a new model for high reactivity of cross-links is proposed.
Abstract: Polymerization kinetics of polyacrylamide gels, cross-linked with the following: N,N′-methylenebisacrylamide (Bis), N,N′-bisacrylylcystamine (BAC), N,N′- diallyltartardiamide (DATD), N,N′(1,2-dihydroxyethylene) bisacrylamide (DHEBA) and ethylene diacrylate (EDA), have been studied. The gels are polymerized directly in a spectrophotometer quartz cuvette and the kinetics followed at 283 nm (disappearance of the double bond) or at 600 nm (Tyndall effect due to turbidity of Bis, DHEBA and BAC gels). The order of reactivity of the various cross-links appears to be: Bis ≅ DHEBA > EDA ≅ BAC ≫ DATD. The last cross-link, (DATD), was found to actually be an inhibitor of gel polymerization, leading to highly unpolymerized gels, especially at high %C values. Bis and DHEBA gels, at 3 to 5 %C levels, are fully polymerized within 30 min at room temperature, while EDA and BAC gels, in the same %C range, require at least 3h. All cross-links, when used above 10 %C, display quite slow polymerization kinetics, requiring overnight reaction for good conversion of monomers into polymer chains. When polymerizing liquid linear polyacrylamide (without cross-link), an initial concentration of > 5% should be used and the reaction continued overnight, at room temperature or higher, for acceptable polymerization efficiency. On the basis of these data, a new structural model for highly cross-linked gels is proposed.
TL;DR: In this paper, the Latemar buildup is used to illustrate the main character of a Lower Ladinian buildup on the slopes of the Southern Alps of Italy, with additional data for the slope taken from Mt. Coldai (Civetta) and Sass da Putia.
TL;DR: Diet-induced fatty acid changes in platelet and aortic lipids, platelet aggregation and thromboxane and prostacyclin formation are discussed and platelet cyclooxygenase appeared to be selectively depressed.
Abstract: Semisynthetic diets containing either corn oil (CO) or butter (B) (11 and 2.2 en % as linoleic acid, respectively) were fed to male rabbits for periods of 3 weeks and 3 months. The CO diet, in respect to the B diet, induced higher levels of linoleic acid (LA) and lower levels of arachidonic acid (AA) in platelet phospholipids, lower levels of AA in aortic phosphatidylinositol (PI) and accumulation of both LA and AA in liver lipids. The thresholds for aggregation with AA, but not with collagen, were higher in the CO group and the formation of thromboxane B2 (TXB2) from [14C] AA, but not from endogenous substrate after collagen stimulation, was lower in the same group. Formation of PGE2-like material by incubated aortas was higher in the B group. In the CO group, platelet cyclooxygenase appeared to be selectively depressed. The correlations among diet-induced fatty acid changes in platelet and aortic lipids, platelet aggregation and thromboxane and prostacyclin formation are discussed.
Journal Article•
TL;DR: In this article, it is suggested that polymerization at 0-4°C should be abandoned, since it leads to unhomogeneous and unreproducible pore size matrices.
Abstract: The temperature at which polyacrylamide gels are polymerized strongly affects the structure and physical properties of this matrix. The suggested temperature of 0–4 °C has been found to produce highly turbid, highly porous and unelastic gels. At temperature of 25 °C of higher, the gels became progressively transparent, less porous and more elastic. This phenomenon is strongly pronounced in N,N′-methylenebisacrylamide (Bis) gels and progressively decreases for N,N′-(1,2-dihydroxyethylene)bisacrylamide (DHEBA) and N,N′-bisacrylylcystamine (BAC) gels. It has been attributed to the formation of hydrogen bonds among cross-linker molecules, which are presumably stabilized by low temperature and progressively broken at higher temperatures. The most extensively H-bonded compounds seem to be Bis molecules, since they can form four H-bonds/molecule, followed by DHEBA (in which inter-molecular H-bonds have to compete with intra-molecular H-bonds) and finally by BAC, which is sparingly H-bonded at 2 °C, and fully uncomplexed at 30°C. It is suggested that polymerization at 0–4°C should be abandoned, since it leads to unhomogeneous and unreproducible pore size matrices. Since H-bonds in Bis molecules are fully disrupted only at 60°C (a temperature unsuitable for gel polymerization, since it produces short chains and unelastic matrices), it is also suggested that the use of Bis should be discontinued in favour of better cross-links, such as DHEBA. In all cases, best polymerization conditions are obtained at 25–30°C. For all three cross-linkers, homogeneous gels are obtained in presence of 8 M urea or in pure formamide as solvent, since both agents fully disrupt H-bonds.
TL;DR: Comparison of the CT scan findings in two matched groups of fluent aphasics showed that phonemic disorders of speech were associated with lesions nearer to the sylvian fissure, while lexical disorders ofspeech were associatedwith lesions farther from the syLVian fISSure.
TL;DR: Data indicate that in ethynylestradiol treated rats S-adenosyl-l-methionine can reverse both cholestasis and related abnormalities of biliary lipids and modify the pattern but not the total amount of bile excretion.
TL;DR: The possibility that the dopamine-inhibited enzyme is located in mammotrophs appears supported by its observation in the female rat pituitary, which contains this type of cells in much larger proportion than the male gland.
TL;DR: An overall positive association was found between the territorial distribution of chloracne cases and the different levels of soil contamination in the affected area, and no clinically definable systemic disease has been diagnosed.
Abstract: Data are presented on the occurrence of chloracne, clinical symptoms and biochemical changes in 164 children following environmental contamination by TCDD from an industrial accident in Seveso, Italy. An overall positive association was found between the territorial distribution of chloracne cases and the different levels of soil contamination in the affected area. Individual risk factors such as condition and length of exposure, intake via contaminated foods, etc. were evaluated; no single factor appeared to be associated with chloracne. Disturbances of the gastrointestinal tract were more frequently observed in children affected with chloracne in those from the same areas having no skin lesions. However, no clinically definable systemic disease has been diagnosed.
TL;DR: The available evidence suggests that this might not be the only subcellular location of the sulfated polypeptide in the pituitary tissue, and that this sulfated component was present in purified bovine prolactin granules stripped of their limiting membrane.
TL;DR: Direct evidence, obtained in some secretory systems, indicates that after exocytosis the granules and plasma membranes do not intermix, but remain segregated.
Abstract: Exocytosis implies the fusion of the membrane of secretion granules with, and the insertion into, the plasmalemma. In non-growing systems such an insertion is temporary in that the inserted membrane is eventually removed. Turnover results indicate that the removed membrane is not destroyed but recycled within the cell and reused. In some systems exocytosis occurs over the entire plasmalemma, while in others it is restricted to discrete regions, characterized by peculiar morphology and composition. Thus the fusion of the two membranes is probably preceded by a recognition step. Structural specializations were detected in interacting granule and plasma membranes by freeze-fracture and surface labelling techniques: arrays of intramembrane particles in protozoans and nerve terminals; clearing of particles and surface antigens in other systems. Direct evidence, obtained in some secretory systems, indicates that after exocytosis the granules and plasma membranes do not intermix, but remain segregated. The subsequent recapture of membrane patches of the granule type (in many systems by means of coated pits and vesicles) could then account for the striking specificity of the recycling process, documented by both composition and structural studies. In different systems the recycling of granule membranes is carried out at greatly different rates. Recent results in the parotid gland and neuromuscular junction indicate that this process is Ca2+-dependent.
TL;DR: The ominous significance of renal impairment in EMC should be revaluated because the high prevalence of hypertension, which was refractory to treatment in six patients, may be important to the clinical outcome.
Abstract: The mode of presentation of renal disease in 44 patients with essential mixed cryoglobulinaemia (EMC) was: acute renal failure (two patients), acute nephritic syndrome (six patients), nephrotic syndrome (eight patients), proteinuria and/or haematuria (28 patients). Renal biopsy, performed in 35 patients showed proliferative lesions in 33, while only minimal glomerular changes were seen in the remaining two. Immunofluorescence studies showed: IgG (85 per cent), IgA (36 per cent), IgM (90 per cent), C3 (90 per cent), C1q (47 per cent), and C4 (33 per cent) deposits, mainly located in subendothelial position. On electron microscopy, crystalloid structure of deposits and monocyte infiltration of capillary loops were the outstanding feature. The survival rate was 75 per cent at 10 years from the onset of clinical symptoms. Thirty-nine patients were followed for three to 146 months (mean 53.8). Twelve patients died, cardiovascular disease and infection being the commonest cause of death. Thirteen patients showed acute renal failure of acute nephritis syndrome: nine recovered completely, whereas the remaining four died during the acute renal episode. Three patients developed chronic renal failure, but only one period required chronic dialysis. The ominous significance of renal impairment in EMC should therefore be revaluated. The high prevalence of hypertension (28/44 patients) which was refractory to treatment in six, may be important to the clinical outcome.
TL;DR: A familial syndrome with hypo-alpha-lipoproteinemia with high prevalence of premature cardiac events was observed in this kindred, without any other established coronary risk factors present.
TL;DR: The sulfur-isotopic composition-age relationships obtained in this article generally agree with those found throughout the world and are almost identical to those published previously for sulfates of Permian and Triassic ages from other locations.
TL;DR: It appears that there are a number of methodological difficulties complicating interpretation of the intellectual deficit based on the Progressive Matrices and Wechsler-Bellevue scores, since performance on these tests is adversely affected by both aphasia and apraxia.
Abstract: The Raven Progressive Matrices and four subtests of the Wechsler-Bellevue Performance Scale were given to 173 left hemisphere patients subdivided according to presence/absence, type (fluent/non-fluent) and severity (moderate/severe) of aphasia. Constructive and ideomotor apraxia scores and CT scan data of each subject entered the statistical analysis. Factors significant in producing a low score on Progressive Matrices and Wechsler-Bellevue were presence of aphasia and constructive apraxia. Site and size of lesion per se failed to account for the intelligence scores. The relationship between aphasia, apraxia, intelligence test scores, and CT scan data were discussed in an attempt to clarify the meaning of these low intelligence test scores in aphasics and to assess the underlying roles of the brain lesions in this deficit. It appears that there are a number of methodological difficulties complicating interpretation of the intellectual deficit based on the Progressive Matrices and Wechsler-Bellevue scores, since performance on these tests is adversely affected by both aphasia and apraxia.
TL;DR: Treatment of therapeutic doses of digitalis in man enhance baroreceptor reflexes, and both the heart rate and the blood pressure reflex effects are involved, however, the enhancement occurs to a marked degree only withbaroreceptor stimulation and is not evident withBaroreceptor deactivation.
Abstract: Data in animals indicate that large amounts of digitalis potentiate arterial baroreflexes and that this factor may be important for the cardiovascular effects of the drug. To determine if arterial baroreflex potentiation also exists after administration of therapeutic doses of digitalis in man, we studied how stimulation and deactivation of arterial baroreceptors by phenylephrine and nitroglycerin injection affect heart rate and how stimulation and deactivation of carotid baroreceptors by neck suction and pressure affects blood pressure and heart rate. The study was performed in 29 normotensive or hypertensive subjects before and after injection of Lanatoside C (0.8 mg i.v.). Baroreceptor stimulation reduced heart rate and blood pressure, while baroreceptor deactivation increased both of these variables. The bradycardic and hypotensive effect of baroreceptor stimulation increased significantly after digitalis both in normotensive and hypertensive subjects. However, the tachycardic and hypertensive responses to baroreceptor deactivation were not affected by digitalis. Thus, therapeutic doses of digitalis in man enhance baroreceptor reflexes, and both the heart rate and the blood pressure reflex effects are involved. However, the enhancement occurs to a marked degree only with baroreceptor stimulation and is not evident with baroreceptor deactivation.
TL;DR: Factor VIII‐related antigen (VIIIR: Ag) was consistently higher than factor‐VIII procoagulant activity (VIII:C) in 57 patients with clinical conditions characterized by acute‐phase reactions.
Abstract: Summary. Factor VIII-related antigen (VIIIR: Ag) was consistently higher than factor-VIII procoagulant activity (VIII:C) in 57 patients with clinical conditions characterized by acute-phase reactions. Two different methods for measuring VIII:C (one- and two-stage assays) and VIIIR: Ag (electroimmunodiffusion and immunoradiometric assay) gave concordant results in the majority of cases. In 43% of plasma samples, crossed immunoelectrophoresis in agarose gel was characterized by the appearance of an additional, fast-moving precipitin peak which was immunologically identical with the major, slower-moving VIIIR : Ag peak. The fast-moving peak was detected in all the patients with clinical conditions typically associated with increased plasma proteolysis (DIC, acute pancreatitis, during thrombolytic therapy). It was present in a smaller proportion of cases with liver and renal failure and malignancies and in the post-operative period. The additional VIIIR : Ag peak is thought to be the result of in vivo factor VIII/von Willebrand factor fragmentation by proteolytic enzymes.