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Showing papers by "University of Florence published in 1981"


Journal ArticleDOI
TL;DR: The early reaction of theAstrocytes suggests that disassembly of glial filaments or new GFA synthesis may contribute to astrocytic changes.

148 citations


Journal ArticleDOI
TL;DR: In this article, major elements, trace elements and 87Sr/86Sr data are reported for the Quaternary potassic alkaline rocks from the Mts. Ernici volcanic area (Southern Latium) in Italy.
Abstract: Major elements, trace elements and 87Sr/86Sr data are reported for the Quaternary potassic alkaline rocks from the Mts. Ernici volcanic area (Southern Latium — Italy). These rocks are represented by primitive types which display high Mgv, low D.I., variable degrees of silica undersaturation and different K2O contents which allowed the distinction of a potassium series (KS) and a high potassium series (HKS). All the analyzed samples have high LIL element contents and high 87Sr/86Sr which ranges between 0.707–0.711. They also have fractionated REE patterns. The KS rocks have lower LIL element concentrations and 87Sr/86Sr ratios than the HKS rocks with a large compositional gap between the two series. Minor but still significant isotopic and trace element variations are also observed within both KS and HKS. The genesis cannot be completly explained either by crystal liquid fractionation, mixing or assimilation processes or by different degrees of equilibrium partial melting from a homogeneous source, thus indicating that both the KS and HKS consist of several geochemically and isotopically distinct magma types. The data suggest that the KS and HKS magmas originated by low degrees of melting of a garnet peridotite mantle heterogeneously enriched in LIL elements and radiogenic strontium, possibly accompanied by disquilibrium melting of some accessory phases. The occurrence of a geochemical anomaly within the mantle is believed to be due to fluid metasomatism probably generated by dehydration of a lithospheric slab subducted during the Late Tertiary development of the Apennine Chain.

122 citations


Journal ArticleDOI
TL;DR: Multiple regression analysis indicated that hypercoagulability and increased platelet biologic activity were not a consequence of differences in risk factor patterns in IHD patients compared to control subjects.

93 citations


Journal ArticleDOI
TL;DR: In this paper, the finite-time regulator problem for linear, autonomous, degenerate systems is studied and two investigations of the regulator problem are presented, which depend on the quadratic cost associated with the differential equation.
Abstract: In this paper, we study the finite-time regulator problem for linear, autonomous, degenerate systems, i.e., systems described by the differential equation $$K\dot x = Ax + Bu(t)$$ with det(K)=0. Two investigations of the regulator problem are presented, which depend on the quadratic cost associated with the differential equation.

79 citations


Book ChapterDOI
E. Casari1
01 Jan 1981
TL;DR: In a meeting in which almost every topic concerning such a connection has undergone or will undergo a direct or indirect, analytical or cursory, theoretical or historical treatment is by no means an easy task as mentioned in this paper.
Abstract: To say something about the connections between logic and the foundations of mathematics in a meeting in which almost every topic concerning such a connection has undergone or will undergo a direct or indirect, analytical or cursory, theoretical or historical treatment is by no means an easy task.

73 citations


Journal ArticleDOI
TL;DR: Findings indicate that TxB2 and PGI2 formation may represent a modulating mechanism of vascular response to adrenergic stimulation.
Abstract: Prostacyclin (PGI2) and thromboxane A2 (TxA2), antiaggregating and aggregating agents, may be involved in the control of local vasomotor tone owing to their vasoactive properties. In 15 healthy young volunteers, circulating PGI2 (biological assay using superfusion technique) and plasma TxA2 levels (measured by radioimmunoassay as its stable derivative TxB2) have been investigated. Adrenergic stimulation was induced by a 2 min cold application and its effectiveness was checked in all subjects by the changes in forearm calculated vascular resistance (blood flow was measured by strain gauge plethysmography), and in six subjects by changes in catecholamine plasma levels (radioenzymatic assay). Cold application induced a sharp increase in calculated vascular resistance and plasma noradrenaline concentration in all subjects. Adrenergic stimulation was associated with a prompt elevation of circulating PGI2 (from 6.67 ± 2.38 to 12.18 ± 2.95 ng·cm−3, P < 0.001) and TxB2 levels (from 0.49 ± 0.18 to 1.10 ± 0.61 pmol·cm−3, P < 0.001). PGI2 and TxB2 increases disappeared within 10 min. In subjects treated with 5 mg·kg−1 ASA, both TxB2 resting levels and their increase after adrenergic stimulation were not significantly different from values before ASA although platelets were unable to produce TxB2. Therefore, platelets were not the source of TxB2 in plasma. After 10 mg·kg−1 ASA, TxB2 increase following adrenergic stimulation was unaffected whereas PGI2 elevation was completely blocked and the increase in calculated vascular resistance was significantly higher than in subjects pretreated with saline. These findings indicate that TxB2 and PGI2 formation may represent a modulating mechanism of vascular response to adrenergic stimulation.

69 citations


Journal ArticleDOI
TL;DR: The predictive power of the consociational model cannot be assessed without a rigorous analysis of the conditions that are conducive to overarching elite cooperation as mentioned in this paper, and neither Lijphart nor other scholars deal satisfactorily with the problem because many of these conditions that they identify often fail to satisfy one or more criteria that test their reliability.
Abstract: The predictive power of the consociational model cannot be assessed without a rigorous analysis of the conditions that are conducive to overarching elite cooperation. However, neither Lijphart nor other scholars deal satisfactorily with the problem because many of the conditions that they identify often fail to satisfy one or more criteria that test their reliability. Only two conditions are unambiguously favourable to consociational cooperation: inter-subcultural stability and elite predominance over a politically deferential and organizationally encapsulated following:

62 citations


Journal ArticleDOI
TL;DR: It is concluded that GABA and glutamate released from the cerebral cortex and diffused into an epidural or cortical cup originate at least in part from the brain and the rate of their release is influenced by changes in neuronal activity.
Abstract: 1. The release of endogenous GABA and glutamate from the cerebral cortex was measured using a cortical cup technique in unanaesthetized freely moving rats and anaesthetized rats by means of a sensitive and specific massspectrometric procedure. 2. GABA release was not affected by the presence of the dura mater or by anaesthesia. Glutamate output was reduced by urethane but not by pentobarbital anaesthesia and by the presence of the dura. 3. An isotonic solution containing 50 mM KCl placed epidurally within the cup elicited a significant short-lasting increase in glutamate output, a decrease in GABA output and a short-lasting electrocorticogram (ECoG) activation. 4. When the dura was removed, a high K+ solution placed on the exposed cerebral cortex elicited a 7–8 fold increase in GABA output accompanied by a marked decrease in glutamate output and by ECoG synchronization. The changes in GABA and glutamate output had parallel time-course and were prevented by the application within the cup of tetrodotoxin (3×10−5 M). 5. Amphetamine at the doses of 3.7 and 7.4 μmol·kg−1 i.v. inereased glutamate output and at the dose of 37 μmol ·kg−1 i.v. increased GABA output. Both effects were prevented or reduced by haloperidol pretreatment (0.65 μmol ·kg−1 i.v.). 6. It is concluded that GABA and glutamate released from the cerebral cortex and diffused into an epidural or cortical cup originate at least in part from the brain. The rate of their release is influenced by changes in neuronal activity. The measurement of their rate of release offers a useful tool for the study of the functional role of cortical GABA and glutamate-releasing neurons.

58 citations


Journal ArticleDOI
TL;DR: The epr spectra at 4.2 K of inhibitor derivatives of cobalt carbonic anhydrase have been recorded and a third kind of epr spectrum with a single broad signal is obtained when the inhibitor is in large excess.

58 citations



Journal ArticleDOI
TL;DR: In this paper, an intermolecular potential is derived for methane molecules using solid-state data, the second virial coefficient of the gas, and the known long-range dispersion forces.

Journal ArticleDOI
TL;DR: In observations at the treatment plant, mutagenic chemicals were produced to a lesser extent by ozone treatment than by chlorination, and ozonation of the chemicals in controlled laboratory experiments resulted in a decrease in themutagenic activity.
Abstract: The mutagenic potential of water taken at various stages in a water treatment plant which used both chlorination and ozonation as methods for disinfection was investigated. Presented in this paper are some of the results obtained using the Salmonella/microsome test. The results of this investigation indicate that while mutagenic chemicals were produced by chlorination, ozonation of the chemicals in controlled laboratory experiments resulted in a decrease in the mutagenic activity. In observations at the treatment plant, mutagenic chemicals were produced to a lesser extent by ozone treatment than by chlorination. (RJC)

Journal ArticleDOI
TL;DR: In the cortical cholinergic nerve endings, depolarization caused by electrical stimulation is coupled with an increase in choline transport which can be modulated by the addition of atropine or physostigmine, and within given experimental conditions a linear relationship exists between the reciprocal of ACh content in the slices and synaptosomal HACU.
Abstract: 1 Superfused guinea-pig cortical slices were electrically stimulated at different frequencies and the changes in acetylcholine (ACh) content measured. Synaptosomes were prepared at the end of the stimulation period and high affinity choline uptake (HACU) rate was measured. 2 The effect of increasing KC1 concentrations was compared on ACh content of the slices and on synaptosomal HACU. 3 Electrical stimulation (2, 5, 10, 20 Hz) elicited a frequency-dependent linear increase in synaptosomal HACU rate and a decrease in ACh content of the slices. 4 The addition of atropine (1.5 x 10(-8) M) to the slices enhanced and that of physostigmine (3 x 10(-5) M) reduced the frequency-dependent increase in HACU rate. Atropine (1.5 x 10(-6) M) not only antagonized the effect of physostigmine, but the HACU rate measured after treatment with both drugs was larger than that found after atropine alone. 5 These results indicate that in the cortical cholinergic nerve endings, depolarization caused by electrical stimulation is coupled with an increase in choline transport which can be modulated by the addition of atropine or physostigmine. Furthermore, within given experimental conditions a linear relationship exists between the reciprocal of ACh content in the slices and synaptosomal HACU.

Journal ArticleDOI
TL;DR: The Aegean volcanic arc is one of the most important geological structures of the Mediterranean area as discussed by the authors, it is a belt of volcanic centers consisting of products ranging from basaltic, andesitic, dacitic to rhyolitic in composition, all of them displaying a typical calc-alkaline chemical character.
Abstract: The Aegean volcanic arc is one of the most important geological structure of the Mediterranean area It is a belt of volcanic centers consisting of products ranging from basaltic, andesitic, dacitic to rhyolitic in composition, all of them displaying a typical calc-alkaline chemical character

Journal ArticleDOI
TL;DR: In this article, it was shown that nuclei are usually produced at sites of identifiable surface imperfection and that such sites are not randomly distributed across the reactant surfaces. But the authors did not discuss the significance of the Arrhenius parameters calculated for these reactions and concluded that local surface stresses exert a more significant control upon these reactions than has hitherto been generally realized.
Abstract: Recent advances in microscope techniques have been used in a reinvestigation of the kinetics of the formation and the growth of nuclei developed during dehydration of cleaved (111) faces of relatively perfect crystals of the alums KAl(SO 4 ) 2 . 12H 2 O and KCr(SO 4 ) 2 . 12H 2 O , and solid solutions of five intermediate compositions, KAl x Cr 1-x (SO 4 ) 2 . 12H 2 O. There was observational evidence that nuclei are usually produced at sites of identifiable surface imperfection and that such sites are not randomly distributed across the reactant surfaces. Nucleation is a deceleratory process and, during the later stages, the continued generation of new reaction sites was associated with surface cracking. The rates of interface advance are constant at the boundaries of established nuclei, though this stability sometimes followed an initial period of either more or less rapid growth. The implications of these observations are discussed for the formulation of yield-time kinetic expressions for solid state decomposition. The activation energies determined for the constant rate of interface advance during dehydrations of chrome alum and the solid solutions were between 70 and 93 kJ mol -1, with no systematic dependence on composition discerned, and the value for aluminium alum was greater (108 kJ mol -1 ). Textural examinations of partially reacted surfaces give evidence that exposure to vacuum results in modification, attributable to water loss, of all the reactant surface and that dehydration is not restricted to the interface comprising the reactant-product contact zone. It is believed that each growth nucleus arises as a consequence of a local recrystallization and this is promoted at the interface by water temporarily retained within cracks and pores of the reactant and between the finely divided product particles. We also conclude that local surface stresses exert a more significant control upon these reactions than has hitherto been generally realized. This model contrasts with many mechanistic features of the accepted theory of the subject. Rates of nucleus growth in the five solid solutions (mixed alums) were less than those of the pure end members, a minimum reactivity was found at the composition 2Al:1Cr. There were no significant changes in activation energy with composition and we discuss the significance of the Arrhenius parameters calculated for these reactions.

Journal ArticleDOI
01 Aug 1981-Pain
TL;DR: An important difference between healthy and pathological subjects is not the quality but the quantity of the changes induced by TENS, in the sense that the levels of inhibition and facilitation of the reflexes are more evident in patients with pain.
Abstract: In healthy subjects and in subjects with chronic myofascial pain of one lower limb, the following was measured in both lower limbs: (i) sequential Hoffman (H) reflex, (ii) sequential Achilles tendon (T) reflex, (iii) cutaneous pain threshold determined with electrical stimuli, before, during and after transcutaneous electrical nerve stimulation (TENS). In healthy subjects no significant differences were observed between the pain thresholds of the two limbs. During and after TENS, changes of the reflexes were related to the pain thresholds. In the pathological subjects a significant difference of pain threshold was present between the affected limb and the contralateral one. An important difference between healthy and pathological subjects is not the quality but the quantity of the changes induced by TENS, in the sense that the levels of inhibition and facilitation of the reflexes are more evident in patients with pain. Indeed, TENS induces a reset of sensory and of motor system and a parallel long lasting effect both on sensory and on muscular function, with concomitant pain relief in the pathological subjects.

Journal ArticleDOI
TL;DR: The results seemed to indicate the usefulness of the Salmonella/microsome test for detection of mutagens in human urine and suggest that people exposed to potentially carcinogenic chemicals may show high enough traces of those chemicals and their metabolites in their body fluids to be detected with current mutagenesis techniques.
Abstract: Urine samples from a control population and from a population of chemical workers from two chemical plants near Florence, Italy, were analyzed for the presence of mutagenic chemicals by the Salmonella/microsome test. When tested with strain TA 1538, the urine of nonsmoking chemical workers showed higher mutagenic activity than that of controls in the presence of in vitro metabolic activation, but no difference was found between controls and chemical workers who both smoked. Increased mutagenic activity was observed in the group of control smokers compared to control nonsmokers, but the same effect was not observed for chemical workers. When TA 100 was used as the tester strain, the chemical workers, both smoking and nonsmoking, had significantly higher mutagenic activity than controls. The mutagenic activity fell to control levels in some workers’ urine after 20 d leave. Although some perturbing effects of smoking habits were observed, the results seemed to indicate the usefulness of the Salmonella/ micro...

Journal ArticleDOI
TL;DR: Treatment with mucopolysaccharidases of both mature leukocytes and marrow stromal cells can interfere in these adhesive relationships, suggesting a role of glycosaminoglycans in regulating short-range interactions during hematopoiesis.

Journal ArticleDOI
TL;DR: In this article, the structure of the [FeH(N2)(P4)]Br · C2H5OH complex was determined from three dimensional X-ray data collected by counter methods.

Journal ArticleDOI
TL;DR: Dipyridamole was found to increase PGI2 production in healthy volunteers, when given both by infusion (8 µg/kg/min × 2 h) and by oral administration (375 mg/day for seven days).
Abstract: The effects of some phosphodiesterase (PDE) inhibitors (dipyridamole, theophylline, papaverine and SH-869) on prostacyclin (PGI2) production have been studied in vitro and in vivo. PGI2 was bioassayed by Vane's superfusion technique. In rabbit aortic rings, only dipyridamole in concentrations from 1 to 12 microM was able to stimulate PGI2 biosynthesis in a dose-dependent manner. This effect was also detected with so-called "exhausted" rabbit aortic rings. The other PDE inhibitors used, both in microM and mM concentration, did not affect PGI2 biosynthesis. Dipyridamole was found to increase PGI2 production in healthy volunteers, when given both by infusion (8 micrograms/kg/min x 2h) and by oral administration (375 mg/day for seven days). Circulating PGI2 and PGI2 production induced by a 3-min period of ischaemia were increased by an average of 137% (p less than 0.001) and 30.8% (p less than 0.001) respectively. Saline and theophylline (as aminophylline) infusions used as controls did not affect PGI2 production.

Journal ArticleDOI
R. Fabbri1
TL;DR: In this article, the spectral shape of the Sunyaev-Zel'dovich effect in the cosmic background radiation was analyzed in detail, taking into account relativistic corrections for a hot electron gas.
Abstract: We analyse in detail the spectral shape of the Sunyaev-Zel'dovich effect in the cosmic background radiation, taking into account the relativistic corrections for a hot electron gas We calculate the displacement of the zero-signal frequency, which is especially informative in a new method for measuring the millimetric temperature of the background radiation; we also present a simple analytical expression, to be used to fit the experimental data in spectral measurements of the effect in very hot cluster gases

Journal ArticleDOI
TL;DR: The regularity results of Hildebrandt-Widman and Wiegner for elliptic systems were generalized to the parabolic case by as mentioned in this paper, where the regularity was shown to be constant.
Abstract: The regularity results of Hildebrandt-Widman and Wiegner for elliptic systems are generalized to the parabolic case.

Journal ArticleDOI
TL;DR: The absolute respiration dependence of cycling resumption by resting ascites cells does not seem to rely on respiratory ATP supply, but rather is linked to the electron flow through the respiratory chain.
Abstract: Resting Yoshida AH130 hepatoma cells, harvested at the plateau of tumor development in vivo, were recruited into the cycling state following transfer to an in vitro system whereby these cells were incubated in the autologous ascites plasma diluted with buffered saline and enriched with glucose. In this system, cell recruitment into the phase of DNA synthesis (S phase) strictly depends on the activity of the respiratory chain and is abolished by anaerobiosis as well as by antimycin A, although the intracellular levels of ATP and the rate of protein synthesis are practically unaffected by these treatments. Furthermore, 2,4-dinitrophenol, at concentrations which uncouple the respiratory phosphorylation and hence enhance both glycolysis and oxygen consumption, does not hinder cell promotion into S phase. Thus, the absolute respiration dependence of cycling resumption by resting ascites cells does not seem to rely on respiratory ATP supply, but rather is linked to the electron flow through the respiratory chain.

Journal ArticleDOI
TL;DR: The electron spin resonance of the Mn(H2O)62+ ion in aqueous solution adsorbed on silica gels with narrow and wide pores has been used to investigate the properties of the water filling the pores as well as the solid-liquid interaction.

Journal ArticleDOI
TL;DR: The results are consistent with a possible neurotransmitter role of ACh and GABA in the striatum and show some differences in the ionic mechanisms underlying GABA and ACh release.
Abstract: The release processes of endogenous Acetylcholine (ACh), γ-aminobutyric acid (GABA), glutamate (Glu) and glutamine (GLN) were studied in superfused guinea-pig caudatal slices. Basal ACh release remained constant for up to 2 h, while the basal release of GABA, Glu and GLN declined to half or less of its initial values after 1 h of superfusion. Electrical stimulation increased the ACh release by 700–800% and that of GABA by 80% whereas it decreased the output of Glu by 50% and failed to modify the GLN efflux. KCl (25 mM) increased the output of ACh by 400%, that of GABA by approximately 500% and decreased that of Glu by 40%. Substituting of CaCl2 by MgCl2 in the superfusion medium reduced the basal ACh release by 70% whereas no differences were observed in the basal efflux of GABA, Glu and GLN. Under these conditions, no evoked release of ACh or of GABA was detected, following electrical or KCl stimulation. Tetrodotoxin 5 × 10-7 M decreased the basal ACh release by 60% and increased the GABA efflux by 40%. The toxin abolished the stimulus-evoked ACh efflux but scarcely affected that of GABA. These results are consistent with a possible neurotransmitter role of ACh and GABA in the striatum and show some differences in the ionic mechanisms underlying GABA and ACh release.

Journal ArticleDOI
TL;DR: In this article, it was shown that large N singularities of parton densities are related by a gauge transformation to a class of collinear singularities, which are calculable to all orders by a change of scale in α S ( Q 2 ).

Journal ArticleDOI
TL;DR: Findings suggest a possible regulatory role of this enzyme in vivo on the calcium transport process by sarcoplasmic reticulum by way of acylphosphatase in rabbit muscle.


Journal ArticleDOI
TL;DR: Results indicated that immunoassay procedures for cortisol based on monitoring chemiluminescence can be developed with these labels.

Journal ArticleDOI
TL;DR: In this article, the magnitude spectra of the modulus v were evaluated from the observed tansient surface tension decay, by proper data manipulation and by adaptation of FT algorithms, taking into account the particular characteristics of the time and frequency domain functions relevant to the examined dynamic properties of fluid interfaces.
Abstract: Computational procedures are devised which allow accurate magnitude spectra of the modulus ɛ(v) to be evaluated from the observed tansient surface tension decay. This is achieved by proper data manipulation and by adaptation of FT algorithms, taking into account the particular characteristics of the time — and frequency — domain functions relevant to the examined dynamic properties of fluid interfaces. Numerical examples, given for 1) exponential-type and 2) diffusion-controlled relaxation mechanisms, show satisfactory accuracy.