Showing papers by "University of Florence published in 1985"
TL;DR: In this article, the authors provide a comprehensive survey of the existing methods and their applications in engineering fields, and present several examples of application of the proposed technique for low-order (second and third) systems.
Abstract: This paper deals with the problem of the estimation of regions of asymptotic stability for continuous, autonomous, nonlinear systems. The first part of the work provides a comprehensive survey of the existing methods and of their applications in engineering fields. In the second part certain topological considerations are first developed and the "trajectory reversing method" is then presented together with a theorem on which it is based. In the final part, several examples of application are reported, showing the efficiency of the proposed technique for low-order (second and third) systems.
470 citations
TL;DR: In this article, both calc-alkaline and K-rich magmas were generated within a mantle heterogenously enriched in LIL elements, by adding material, probably sediments, dragged down by the undergoing slab.
Abstract: Geochemical data on mafic volcanics show that important affinities exist between the Roman and the calc-alkaline rocks from the Aeolian arc (south Tyrrhenian Sea). These affinities, together with the close association of calc-alkaline and K-rich volcanics in the Aeolian arc and in the Naples area, the continuity in the variation of abundances of incompatible elements from calc-alkaline to potassic suites, and the similarity in terms of major-element geochemistry, support a genetic relationship of the Roman magmatism and the subduction processes that affected the Apennines in Tertiary time and are still active under the Aeolian arc. In the genetic model presented here, both calc-alkaline and K-rich magmas were generated within a mantle heterogenously enriched in LIL elements. Composition of the mantle was modified by addition of material, probably sediments, dragged down by the undergoing slab. The geochemical and petrological differences displayed by the calc-alkaline and K-rich volcanics are accounted for by the different conditions of melting as well as by chemical and isotopic heterogeneities of the source. 26 references, 3 figures, 1 table.
195 citations
TL;DR: Voluntary contraction of target muscles remarkably enhanced MAP amplitudes during scalp, but not during spine stimulation, and anodal stimuli showed liminal values significantly lower than the cathodal ones.
157 citations
TL;DR: The path-integral method is used for determination of the quantum corrections to the free energy of nonlinear systems and an effective potential to be inserted in the configurational integral is found.
Abstract: The path-integral method is used for determination of the quantum corrections to the free energy of nonlinear systems. All quantum effects of the harmonic part of the potential are considered and a variational principle is used to account for the quantum corrections due to the anharmonic part. Correct renormalized frequencies are obtained at any temperature and an effective potential to be inserted in the configurational integral is found. A new general expression for the partition function at any temperature in the low-coupling limit is obtained.
154 citations
TL;DR: In this paper, a modified sample preparation technique was used to establish a detailed lower Campanian to upper Eocene nannofossil stratigraphy in the Bottaccione and Contessa Highway sections near Gubbio.
153 citations
TL;DR: In this article, a uniform high-frequency solution is presented for the diffraction by a wedge with impedance faces illuminated by a plane wave perpendicularly incident on its edge, and both the transverse electric (TE) and transverse magnetic (TM) cases are considered.
Abstract: A uniform high-frequency solution is presented for the diffraction by a wedge with impedance faces illuminated by a plane wave perpendicularly incident on its edge. Arbitrary uniform isotropic impedance boundary conditions may be imposed on the faces of the wedge, and both the transverse electric (TE) and transverse magnetic (TM) cases are considered. This solution is formulated in terms of a diffraction coefficient which has the same structure as that of the uniform geometrical theory of diffraction (UTD) for a perfectly conducting wedge. Its extension to the present case is achieved by introducing suitable multiplying factors, which have been derived from an asymptotic evaluation of the exact solution given by Maliuzhinets. When the field point is located on the surface near the edge, a more accurate asymptotic evaluation is employed to obtain a high-frequency expression for the diffracted field, which is suitable for several specific applications. The formulation described in this paper may provide a useful, rigorous basis to search for a more numerically efficient but yet accurate approximation.
142 citations
TL;DR: The results of this study refute the commonly held belief that all thyroid tumors containing clear cells are malignant, and do not support the concept of "clear cell carcinoma" of the thyroid as a specific microscopic entity.
Abstract: Thirty-eight primary thyroid neoplasms with extensive (greater than or equal to 50%) clear cell changes were studied. These were divided into four categories: 1) Hurthle cell tumors, 10 cases; 2) follicular tumors, 17 cases (two of them having a signet-ring or lipoblast-like appearance); 3) papillary carcinomas, seven cases; and 4) undifferentiated carcinomas, four cases. These were compared with eight cases of renal cell carcinoma metastatic to the thyroid. Factors resulting in the cytoplasmic clear cell changes were: 1) formation of medium-sized vesicles, many of apparent mitochondrial derivation; 2) accumulation of glycogen (with or without accompanying fat); and 3) deposition of intracellular thyroglobulin. Vesicle formation was the most common cause of clear cell change in Hurthle cell and follicular tumors; glycogen accumulation in papillary, undifferentiated, and metastatic tumors; and thyroglobulin deposition in the subgroup of follicular tumors with a signet-ring or lipoblast-like appearance. However, several exceptions were noted. The results of this study refute the commonly held belief that all thyroid tumors containing clear cells are malignant, and do not support the concept of "clear cell carcinoma" of the thyroid as a specific microscopic entity. We believe that the natural history of thyroid tumors containing clear cells is more dependent on their basic cytoarchitectural features than on the presence, amount, or type of clear cells, and we suggest for these tumors to be evaluated for carcinoma by using standard morphologic criteria for their respective types. The importance of thyroglobulin staining for the differential diagnosis with metastatic renal cell carcinoma is emphasized, but the pitfalls inherent to this technique are also pointed out.
130 citations
TL;DR: This paper describes a technique for increasing the efficiency of an ARQ communication system utilizing error detection codes, in which the blocks containing errors are not discarded at the receiver, as in the conventional ARQ systems.
Abstract: This paper describes a technique for increasing the efficiency of an ARQ communication system utilizing error detection codes. In this technique the blocks containing errors are not discarded at the receiver, as in the conventional ARQ systems. Such blocks are retained in order to make use of the information contained in them. A reliability value is associated to each demodulated symbol; this reliability value is updated every time a new retransmission is made, even if the vector received is in error. The process of updating the symbols often eliminates automatically the errors introduced by the channel. The results obtained by means of a simulation show that this method offers a considerable reduction in the average number of retransmissions, in comparison with conventional ARQ systems.
126 citations
TL;DR: The life events experienced in the 12 months prior to the first panic attack were studied in patients with a DSM-III diagnosis of panic disorder as well as in healthy subjects matched for age, sex, social and educational level.
119 citations
TL;DR: These studies show that Polysorbate 80 releases histamine both in vitro and in isolated mast cells from rats and in vivo in the dog, and that the plasma concentrations are correlated with the haemodynamic responses.
Abstract: The solvent of commercial amiodarone (Polysorbate 80) has been reported to produce haemodynamic responses in humans and in dogs similar to those produced by histamine infusion. We therefore evaluated the correlation between hypotension induced by the solvent of amiodarone and its histamine-releasing properties in the awake dog.
104 citations
TL;DR: In this paper, a tentative seismotectonic model of the Northern Apennines is discussed, which is based on the structural evolution and crustal structure, in which the earthquake distribution can find a coherent framework.
TL;DR: GM1 treatment improved acquisition of the active avoidance response in the lesioned rats as indicated by a larger number of avoidances and a smaller number of escape failures during training in comparison with saline treatment.
TL;DR: The results suggest that the structures in the deep, ventro-lateral aspect of rostral medulla, from which apnoea can be induced, correspond partly to the nucleus paragigantocellularis lateralis (nPGL) and the nucleus preolivaris, which appear to be relevant for the drive inputs necessary for respiratory rhythmogenesis.
Abstract: Unilateral focal cold blocks (20 degrees C) in structures located ventrolaterally in rostral medulla consistently caused apnoea or deep depression of inspiratory motor output. The inhibitory effect could be correlated with the cooling temperature. Apnoeic response occurred either with complete absence of any inspiratory activity or combined with low level tonic inspiratory motor activity ('tonic apnoea'). The appearance of apnoea was CO2-independent, whereas the tonic component of the latter increased with increasing levels of PCO2. The results suggest that the structures in the deep, ventro-lateral aspect of rostral medulla, from which apnoea can be induced, correspond partly to the nucleus paragigantocellularis lateralis (nPGL) and the nucleus preolivaris. These structures appear to be relevant for the drive inputs necessary for respiratory rhythmogenesis. Unilateral focal cooling in the rostral medulla, including the 'Botzinger Complex', caused increments in respiratory rate both in vagotomized and non-vagotomized animals. The increase in respiratory rate in response to cooling in the region of the 'Botzinger Complex' was combined with either an enhancement or some depression of respiratory motor output. This area in the rostral part of the ventral respiratory group (VRG) seems not to be crucial for respiratory rhythmogenesis, but to play a role in determining both the intensity and timing of the respiratory activity. All effects of unilateral cold block were bilaterally symmetrical.
TL;DR: In this article, the authors reported the discovery of cold brines in an entirely different geodynamic situation, a convergent plate boundary in the eastern Mediterranean, where the heatflow is very low and no hydrothermal activity occurs.
Abstract: In 1968 hot brines from which gypsum had precipitated were discovered in the Red Sea, in a divergent plate boundary setting with hydrothermal activity1. We now report the discovery of cold brines in an entirely different geodynamic situation, a convergent plate boundary in the eastern Mediterranean, where the heatflow is very low2 and no hydrothermal activity occurs. Decimetric pure gypsum crystals precipitate from the cold brines, which occupy the bottom of a rimmed anoxic basin near the southern edge of the Mediterranean Ridge, close to the Sirte Abyssal Plain. Nucleation of the crystals does not occur at the surface, but from the deep brines, because the salinity of the water is normal down to the depth of −3,000 m. We propose the name ‘Bacino Bannock’ for this basin, after the Consiglio Nazionale delle Ricerche R/V Bannock from which the bottom-water brines were surveyed and sampled.
TL;DR: In this paper, the relation between mass movements, rainfall and interstitial pressures is examined to evaluate the relations between mass movement, rainfall, and the interstitial pressure in rock slides and earth slides.
Abstract: Old landslides in precarious conditions and new masses are moved or removed by particularly heavy rainfalls. Phenomena relative to rock slides and earth slides are examined to evaluate the relations between mass movements, rainfall and interstitial pressures.
TL;DR: It is proposed that the chronic phosphatidylserine treatment may reduce the age-induced decrease in acetylcholine release by acting on the stimulus-secretion coupling mechanism.
TL;DR: Findings confirm that adenomatous polyps are not limited to the colon and rectum, as previously believed, but can affect the whole gastrointestinal tract and periodic surveillance of mucosa seems to be indicated.
Abstract: Endoscopy and biopsy of the upper gastrointestinal tract and terminal ileum were performed in 24 patients with familial polyposis or Gardner's syndrome in order to further define the incidence of extracolonic adenomatous polyps. Polyps, usually multiple and small in size, were detected in the gastric fundus (12.5 percent), antrum (29.1 percent), duodenum (66.6 percent), and terminal ileum (41.7 percent). Histology showed hyperplasia of the fundic glands and cystic dilatation in the polyps of gastric fundus, and adenomas in several cases of antral (three patients) or duodenal polyps (14 patients). Polyps of the terminal ileum were either adenomas (five patients) or lymphoid aggregates. Patients with stigmata of Gardner's syndrome, desmoids or mesenteric fibromatosis presented a major incidence of adenomas in the duodenum, but not in other parts of the digestive tract investigated. Subsequent checkup after an average of 33 months in ten patients revealed an increase of lesions only in the duodenum in two patients. These findings confirm that adenomatous polyps are not limited to the colon and rectum, as previously believed, but can affect the whole gastrointestinal tract. Periodic surveillance of mucosa seems to be indicated, especially for the duodenum, since degeneration of adenomas into carcinoma is possible
TL;DR: In this article, an equation for the field dependence of nuclear T1−1 enhancement due to dipolar coupling with an electron of spin 1 2 which takes into consideration g anisotropy under slow rotation conditions was derived.
TL;DR: In this paper, the final degradative pathways of atrazine (I) by a Nocardia strain through experiments on the degradation of its metabolite, 4-amino-2-chloro-6-isopropylamino-1,3,5-triazine (IIa), were elucidated.
Abstract: The purpose of this paper is to elucidate the final degradative pathways of atrazine (I) by a Nocardia strain through experiments on the degradation of its metabolite, 4-amino-2-chloro-6-isopropylamino-1,3,5-triazine (IIa). This compound, in the bacterial medium, was transformed into several products identified as 2-chloro-4,6-diamino-1,3,5-triazine (IIc), 4-amino-2-hydroxy-6-isopropylamino-1,3,5-triazine (VIII), 4-amino-1,2-dihydro-1,3,5-triazin-2-one (IV) and dicyanodi-amidine (VII). The formation of (IIc) was attributed to a microbial N-dealkylation, while the detection of (IV) and (VII) was attributed to a chemical degradation of the intermediate 4-amino-2-chloro-1,3,5-triazine (III). Compound (III) undergoes rapid hydrolysis and does not accumulate in the culture medium. On the basis of the microbial and chemical results, we propose a degradative pathway for atrazine.
01 Dec 1985
TL;DR: In this paper, the authors studied local properties of a control system via polynomial approximations induced by suitable filtrations of the Lie Algebra associated to the system.
Abstract: This paper is concerned with studying some local properties of a control system via polynomial approximations induced by suitable filtrations of the Lie Algebra associated to the system. The approximations may be obtained by means of a finite algorithm.
TL;DR: The results suggest that aging of the aorta is accompanied by an increase both in collagen content and in total sugar content when expressed as mg/cm2 while the elastin content, when expressed in the same way, does not undergo any variation.
Abstract: The biochemical analysis of samples of aortic connective tissue was carried out in 22 subjects from 9 to 84 years old.Aortic samples were taken at necropsy performed after sudden or, more often, traumatic death. The results suggest that aging of the aorta is accompanied by an increase both in collagen content and in total sugar content when expressed as mg/cm2 while the elastin content, when expressed in the same way, does not undergo any variation.
TL;DR: Evaluating the course of the disease according to the site and type of operation shows that non-radical surgical treatment associated with radiotherapy seems to give results comparable to those obtained with radical surgery alone.
Abstract: Thirty-seven cases of adenoid cystic carcinoma treated at the Otolaryngologic Clinic of the University of Florence between 1962 and 1979 were studied. The patients were treated with radical surgical excision (20), non-radical surgery associated with radiotherapy (13), or with palliative treatment (4). The aim of this study is to evaluate the course of the disease according to the site and type of operation. Our results show that non-radical surgical treatment associated with radiotherapy seems to give results comparable to those obtained with radical surgery alone.
TL;DR: In this article, transferrin and ceruloplasmin have been measured by a solid-phase chemiluminescent method in seminal fluid and circulating blood of normal and vasectomized subjects (1 year after operation).
TL;DR: The aqua(1,10-phenanthroline)(oxalato-O1O2) copper(II)monohydrate was synthesized and characterized by spectroscopy, thermal analysis, EPR and structural measurements as discussed by the authors.
TL;DR: The postoperative course was evaluated for 458 consecutive patients, all over the age of 56 years, who had undergone laryngeal conservation surgery in the last 10 years.
Abstract: The postoperative course was evaluated for 458 consecutive patients, all over the age of 56 years, who had undergone laryngeal conservation surgery in the last 10 years. One hundred seventy-one patients aged 66 and over made up the "elderly" group and 287 patients, aged between 56 and 65 years formed the control group. It was confirmed that cordectomy and frontolateral laryngectomy are feasible even in elderly patients. Bronchopneumonia is the most frequent and serious complication after supraglottic laryngectomy. Therefore this operation should be performed in the elderly patient only after a thorough evaluation of cardiac and respiratory function. Prophylactic neck dissection should not be done for N0 necks and the second therapeutic neck dissection in N2 cancers should be staged 6 or more weeks later. Hemilaryngopharyngectomy and subtotal reconstructive laryngectomy with cricohyoidpexis are not advisable in elderly patients.
TL;DR: The results suggest that theDRG and VRG areas exert somewhat different effects on the respiratory pattern: DRG appears to be more concerned with integration of vagal and other inputs contributing to the inspiratory off-switch mechanisms which, however, are not confined only to the DRG.
Abstract: Unilateral focal cold blocks in the region of the nucleus tractus solitarius and the dorsal respiratory group of neurons, DRG, of anaesthetized cats consistently caused apneustic-type breathing. There was no concomitant change in the initial rate of rise of inspiratory activity. The apneustic prolongation of inspiratory duration, T1, was most pronounced in, but was not confined to, the DRG. The apneustic effects were more marked after vagotomy. In cats with intact vagus nerves being given artificial ventilation, focal cooling at certain sites of the DRG region could produce ‘unlocking’ of the respiratory rhythm from that of the respiratory pump. At other sites in this region, focal cooling could selectively block the effects of the inspiration-facilitating reflex induced by deflation without blocking the inspiration-inhibiting Hering-Breuer reflex. Unilateral focal cold blocks in the region of the intermediate part of the ventral respiratory group of neurons, VRG, generally caused depression of the rate of rise of inspiratory activity, but almost never apneustic effects. All effects of unilateral focal cooling both in the DRG and VRG were bilaterally symmetrical. No systematic differences between the effects on phrenic and external intercostal inspiratory activity were found in response to focal cooling either of the DRG or VRG suggesting that differential control of phrenic and external intercostal motoneurons is not exerted mainly at the level of these medullary structures. The results suggest that the DRG and VRG areas exert somewhat different effects on the respiratory pattern: DRG appears to be more concerned with integration of vagal and other inputs contributing to the inspiratory off-switch mechanisms which, however, are not confined only to the DRG. The VRG inspiratory mechanisms, on the other hand, appear to be more involved in the gain control of the inspiratory output intensity.
TL;DR: During spontaneous and histamine induced attacks in the cluster phase, plasma EKA was increased in comparison with the values in controls and it remains to be seen whether variations of plasma SPLI and EKA levels play a role in the CH mechanism.
Abstract: Substance P (SP), present in sensory afferent neurons, seems to process nociceptive information in the trigeminal system. SP, released from peripheral trigeminal endings, causes typical cluster headache (CH) signs, e.g. vasodilatation, conjunctival and nasal edema and miosis. Opiates and somatostatin (SRIF), both active in relieving CH attack, inhibit SP release from the central and peripheral trigeminal system. In the present study, plasma and cerebrospinal fluid (CSF), SP-like immunoreactivity (SPLI) and enkephalinase activity (EKA), and plasma SRIF-like immunoreactivity (SRIFLI) have been evaluated during spontaneous and histamine induced attacks in the cluster phase. During the histamine provoked attacks, CSF SPLI and plasma SRIFLI and EKA were unchanged, while plasma SPLI decreased significantly. During spontaneously occurring attacks, plasma SRIFLI was found to be unmodified and a significant lowering of SPLI was detected when compared with controls. Moreover, both during and between attacks in the cluster phase, plasma EKA was increased in comparison with the values in controls. It remains to be seen whether variations of plasma SPLI and EKA levels play a role in the CH mechanism.
TL;DR: Nonsignificant hemodynamic change was observed in the placebo subsets, and FDP failed to exert any effect in subsets 1, 2 and 3; a 24% increase in cardiac index occurred 60 minutes after FDP in subset 4, and LV stroke work index increased, while PA wedge pressure remained unchanged.
Abstract: Acute hemodynamic and electrocardiographic effects of fructose-1,6-diphosphate (FDP), an agent that is supposed to restore anaerobic glycolytic flux in the ischemic myocardium, were studied in 40 patients with acute myocardial infarction who were grouped into 4 subsets: subset 1, normal (15 mm Hg or less) pulmonary artery (PA) wedge pressure and normal (35 g-m/m2 or greater) left ventricular (LV) stroke work index; subset 2, elevated (more than 15 mm Hg) PA wedge pressure and normal LV stroke work index; subset 3, normal PA wedge pressure and reduced (less than 35 g-m/m2) LV stroke work index; subset 4, elevated PA wedge pressure and LV stroke work index moderately reduced to a range between 16 and 34 g-m/m2. Patients were randomized into an FDP (250 mg/kg body weight in isotonic saline solution intravenously in 20 minutes) and into a placebo group. Each subset contained 5 FDP- and 5 placebo-treated patients. After basal measurements, hemodynamic measurements were reassessed at 60, 90 and 120 minutes from the infusions, while a standard 12-lead electrocardiogram was recorded in the basal state and 120 minutes after infusion. Nonsignificant hemodynamic change was observed in the placebo subsets, and FDP failed to exert any effect in subsets 1, 2 and 3. A 24% (p less than 0.02) increase in cardiac index occurred 60 minutes after FDP in subset 4. LV stroke work index also increased, while PA wedge pressure remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: Soit x˙(t)=f(t,x(t))t∈J, x∈S, ou JCR est un intervalle donne, f:J×R n →R n est une fonction continue, et S un sous-ensemble de C(J,R n ) as discussed by the authors, l'espace des fonctions continues de J dans R n.
Abstract: Soit x˙(t)=f(t,x(t))t∈J, x∈S, ou JCR est un intervalle donne, f:J×R n →R n est une fonction continue, et S un sous-ensemble de C(J,R n ) ― l'espace des fonctions continues de J dans R n . On considere l'equation operateur associee x=T(x) ou T est un operateur non lineaire, discontinu dans son domaine
01 Nov 1985-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The capacity of Talitrus saltator populations to adapt to variations in shoreline directions within a limited space was evaluated by testing both adults collected at different points along continuous sandy arcs, and the 1st and 2nd generations of their laboratory-born offspring (exposed to the sun for the first time during testing) as discussed by the authors.
Abstract: The capacity ofTalitrus saltator populations to adapt to variations in shoreline directions within a limited space was evaluated by testing both adults collected at different points along continuous sandy arcs, and the 1st and 2nd generations of their laboratory-born offspring (exposed to the sun for the first time during testing). Solar orientation of the adults was adapted to the direction of the shoreline at the capture point, and significant statistical differences appeared between lots from different points. The innate directional tendency of the laboratory-born populations differed between collecting points only a few km apart. Solar direction-finding is thus genetically determined, and these results presuppose a genetic heterogeneity within the natural populations. Individually acquired components could improve orientation in nature.