Showing papers by "University of Cagliari published in 1997"
TL;DR: In this paper, the spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry-phase approach to polarization in solids.
Abstract: The spontaneous polarization, dynamical Born charges, and piezoelectric constants of the III-V nitrides AlN, GaN, and InN are studied ab initio using the Berry-phase approach to polarization in solids. The piezoelectric constants are found to be up to ten times larger than in conventional III-V and II-VI semiconductor compounds, and comparable to those of ZnO. Further properties at variance with those of conventional III-V compounds are the sign of the piezoelectric constants (positive as in II-VI compounds) and the very large spontaneous polarization.
2,785 citations
TL;DR: Delta9-THC and heroin exert similar effects on mesolimbic dopamine transmission through a common mu1 opioid receptor mechanism located in the ventral mesencephalic tegmentum.
Abstract: The effects of the active ingredient of Cannabis, Delta9-tetrahydrocannabinol (Delta9-THC), and of the highly addictive drug heroin on in vivo dopamine transmission in the nucleus accumbens were compared in Sprague-Dawley rats by brain microdialysis Delta9-THC and heroin increased extracellular dopamine concentrations selectively in the shell of the nucleus accumbens; these effects were mimicked by the synthetic cannabinoid agonist WIN55212-2 SR141716A, an antagonist of central cannabinoid receptors, prevented the effects of Delta9-THC but not those of heroin Naloxone, a generic opioid antagonist, administered systemically, or naloxonazine, an antagonist of micro1 opioid receptors, infused into the ventral tegmentum, prevented the action of cannabinoids and heroin on dopamine transmission Thus, Delta9-THC and heroin exert similar effects on mesolimbic dopamine transmission through a common mu1 opioid receptor mechanism located in the ventral mesencephalic tegmentum
1,071 citations
796 citations
TL;DR: In this paper, a general theory is developed which provides explicit criteria for the choice of the operating conditions of simulated moving bed (SMB) units to achieve the prescribed separation of a mixture characterized by both constant selectivity Langmuir isotherms and variable selectivity modified LSHs.
559 citations
TL;DR: In this paper, the effect of land use and precipitation on annual runoff and sediment loss was investigated in eight different sites along the northern Mediterranean region and the Atlantic coastline located in Portugal, Spain, France, Italy and Greece.
Abstract: The effect of land use and precipitation on annual runoff and sediment loss was investigated in eight different sites along the northern Mediterranean region and the Atlantic coastline located in Portugal, Spain, France, Italy and Greece. These sites represent a variety of landscapes and are under a number of land-uses representative of the Mediterranean region, such as agricultural land with rainfed cereals, vines, olives, eucalyptus plantation or natural vegetation (shrubland). It was found that land use can greatly affect runoff and soil erosion. The greatest rates of runoff and sediment loss were measured in hilly areas under vines (average sediment loss 142.8 t km −2 yr −1 ). Areas cultivated with wheat are sensitive to erosion, especially during winter, generating intermediate amounts of runoff and sediment loss (17.6 t km −2 yr −1 ) especially under rainfalls higher than 280 mm per year. Olives grown under semi-natural conditions, as for example with an understory of vegetation of annual plants greatly restrict soil loss to nil values (0.8 t km −2 yr −1 ). Erosion in shrublands increased with decreasing annual rainfall to values in the range 280–300 mm and then it decreased with decreasing rainfall (average sediment loss 6.7 t km −2 yr −1 ).
495 citations
TL;DR: An overview of the various models and problems formulated in the literature focusing on two particular models, the controlled Petri nets and the labeled nets, and two efficient techniques for the on-line computation of the control law.
Abstract: This paper surveys recent research on the application of Petri net models to the analysis and synthesis of controllers for discrete event systems. Petri nets have been used extensively in applications such as automated manufacturing, and there exists a large body of tools for qualitative and quantitative analysis of Petri nets. The goal of Petri net research in discrete event systems is to exploit the structural properties of Petri net models in computationally efficient algorithms for computing controls. We present an overview of the various models and problems formulated in the literature focusing on two particular models, the controlled Petri nets and the labeled nets. We describe two basic approaches for controller synthesis, based on state feedback and event feedback. We also discuss two efficient techniques for the on-line computation of the control law, namely the linear integer programming approach which takes advantage of the linear structure of the Petri net state transition equation, and path-based algorithms which take advantage of the graphical structure of Petri net models. Extensions to timed models are briefly described. The paper concludes with a discussion of directions for future research.
441 citations
TL;DR: Results indicate that recruitment of histone acetyltransferase activity of PCAF by MyoD, through p300/CBP, is crucial for activation of the myogenic program.
426 citations
TL;DR: In this article, a novel food (Fonzies) to rats fed ad libitum with standard food increased extracellular dopamine (DA) in the medial prefrontal cortex (PFCX) and medial nucleus accumbens (NAc).
Abstract: Feeding a novel food (Fonzies) to rats fed ad libitum with standard food increased extracellular dopamine (DA) in the medial prefrontal cortex (PFCX) and in the medial nucleus accumbens (NAc). Previous Fonzies feeding, although it did not affect the increase of extracellular DA in the PFCX in response to Fonzies feeding, blunted that increase in the NAc (habituation); recovery from habituation in the NAc was complete 5 d after previous Fonzies feeding. Predictive association of an otherwise neutral stimulus extrinsic to Fonzies (empty plastic box) with Fonzies feeding resulted in the acquisition by the stimulus of the property to elicit incentive responses directed toward the stimulus and to increase extracellular DA in the PFCX. However, the same stimulus, or a more complex stimulus including intrinsic stimuli (Fonzies-filled plastic box), failed to acquire the ability to modify extracellular DA in the NAc. Pseudoconditioning, i.e., nonpredictive association of the extrinsic stimulus (empty box) with Fonzies feeding, did not result in acquisition by the stimulus of the property to elicit incentive responses and to increase extracellular DA in the PFCX. Repeated nonreinforced presentation of previously conditioned extrinsic stimuli (empty box) resulted in extinction of the property to elicit incentive responses and to increase extracellular DA in the PFCX. These results indicate that in rats fed ad libitum, phasic activation of mesocortical and mesolimbic DA systems by motivational stimuli is differentially influenced by associative (conditioning) and nonassociative (habituation) learning mechanisms and is differentially related to acquisition and expression of incentive motivation.
382 citations
TL;DR: It is demonstrated that, in differentiating skeletal muscle cells, p300 physically interacts with the myogenic basic helix–loop–helix (bHLH) regulatory protein MyoD at its DNA binding sites, and p300 potentiates MyOD‐ and myogenin‐dependent activation of transcription from E‐box‐containing reporter genes.
Abstract: The nuclear phosphoprotein p300 is a new member of a family of 'co-activators' (which also includes the CREB binding protein CBP), that directly modulate transcription by interacting with components of the basal transcriptional machinery. Both p300 and CBP are targeted by the adenovirus E1A protein, and binding to p300 is required for E1A to inhibit terminal differentiation in both keratinocytes and myoblasts. Here we demonstrate that, in differentiating skeletal muscle cells, p300 physically interacts with the myogenic basic helix-loop-helix (bHLH) regulatory protein MyoD at its DNA binding sites. During muscle differentiation, MyoD plays a dual role: besides activating muscle-specific transcription, it induces permanent cell cycle arrest by up-regulating the cyclin-dependent kinase inhibitor p21. We show that p300 is involved in both these activities. Indeed, E1A mutants lacking the ability to bind p300 are greatly impaired in the repression of E-box-driven transcription, and p300 overexpression rescues the wild-type E1A-mediated repression. Moreover, p300 potentiates MyoD- and myogenin-dependent activation of transcription from E-box-containing reporter genes. We also provide evidence, obtained by microinjection of anti-p300 antibodies, that p300 is required for MyoD-dependent cell cycle arrest in either myogenic cells induced to differentiate or in MyoD-converted C3H10T1/2 fibroblasts, but is dispensable for maintenance of the postmitotic state of myotubes.
289 citations
TL;DR: The results suggest that lower serum Zn is a marker of TRD and of the immune/inflammatory response in depression, and it is suggested that treatment resistance may bear a relationship with theimmune/inflammatory alterations in major depression.
250 citations
TL;DR: The solution of a tracking problem for a secondorder nonlinear system with uncertain dynamics and incomplete state measurement is obtained by means of a procedure directly inspired by the solution of the classical minimum-time optimal control problem.
TL;DR: In this paper, the static and electronic dielectric tensors of polar insulating crystals were calculated based on concepts from the modern theory of dielectrics polarization, and the first ab initio calculation of the constants in the wurtzite III-V nitrides AlN, GaN, and InN was presented.
Abstract: We present a novel method for the calculation of the static and electronic dielectric tensor of polar insulating crystals based on concepts from the modern theory of dielectric polarization. As an application, we present the first ab initio calculation of the dielectric constants in the wurtzite III-V nitrides AlN, GaN, and InN. [S0031-9007(97)04523-7]
TL;DR: In this article, an orthogonal collocation method based on moving finite elements has been developed for simulating fixed-bed adsorbers, where the movement of the grid is calculated explicitly before starting the integration of the discretized equations, using the results of the equilibrium theory for wave transitions and the shock layer theory for shock transitions.
TL;DR: Observations indicate that inhibition of GABAergic transmission, induced by foot shock or pharmacological manipulations, results in an increase in the concentrations of AP in brain and plasma, possibly via a modulation of hypothalamic‐pituitary‐adrenal (HPA) axis.
Abstract: 1. This study was undertaken to investigate the relationship between a reduction in brain GABAA receptor function and the cerebro-cortical content of 3 alpha-hydroxy-5 alpha-pregnan-20 one (allopregnanolone, AP), a potent endogenous positive modulator of 7-aminobutyric acid (GABA) action at GABAA receptors, with anticonflict and anticonvulsant effects in rodents. 2. An acute depletion of the cerebral content of GABA or an attenuation of GABAA receptor-mediated transmission by systemic injections of isoniazid (375 mg kg-1, s.c.) or FG 7142 (15 mg kg-1, i.p.) induced a transient increase in the cerebro-cortical and plasma concentrations of AP in handling-habituated (not stressed) rats. 3. Two stress paradigms, handling in naive rats and mild foot shock in handling-habituated rats, that reduce central GABAergic tone mimicked the effects of isoniazid and FG 7142 on cortical AP content; foot shock in handling-habituated rats, but not handling in naive animals, also increased plasma AP. Isoniazid, FG 7142, and foot shock also each increased the concentrations of the AP precursors, pregnenolone and progesterone, in both brain and plasma of handling-habituated rats, whereas handling in naive rats increased the concentrations of these steroids only in brain. 4. Pretreatment of handling-habituated rats with the anxiolytic beta-carboline derivative abecarnil, a positive allosteric modulator of GABAA receptors, which per se failed to affect the AP concentration in brain or plasma, prevented the increase in brain and plasma AP induced by foot shock or isoniazid. 5. In adrenalectomized and castrated rats foot shock or isoniazid failed to increase AP both in brain cortex and plasma. 6. These observations indicate that inhibition of GABAergic transmission, induced by foot shock or pharmacological manipulations, results in an increase in the concentrations of AP in brain and plasma, possibly via a modulation of hypothalamic-pituitary-adrenal (HPA) axis. 7. Given that AP enhances GABAA receptor function with high efficacy and potency, an increase in brain AP concentration may be important in the fine tuning of the GABA-mediated inhibitory transmission in the central nervous system.
TL;DR: In this article, a model is developed, based on neurocomputing, for predicting, with sufficient approximation, the compressive strength of cement conglomerates, and the experimental data obtained during construction of the "Alto Sulcis Thermal Power Station" at Portovesme, Italy, were used in the tests.
TL;DR: It is suggested that amphetamine and cocaine increase extracellular DA in the PFCX largely through the blockade of the NA carrier, and direct evidence for this hypothesis was provided by the observation that, when theNA carrier was blocked by reverse dialysis of the P FCX with desipramine, cocaine and GBR 12909 lost their differences in the ability to increase extracllular DA.
Abstract: This study was performed to investigate the relative role of noradrenaline (NA) and dopamine (DA) carrier blockade in the effects of psychostimulants on DA transmission in the rat prefrontal cortex (PFCX). To this end, changes of extracellular DA and NA in the PFCX and of extracellular DA in the nucleus accumbens (NAc) were measured following the administration of amphetamine and cocaine, which are known to bind to both DA and NA carriers, or GBR 12909, a selective DA carrier blocker. After non-intravenous injection, amphetamine (0.25 and 0.5 mg/kg, s.c.) and cocaine (5 and 10 mg/kg, i.p.) increased extracellular DA in the PFCX to a larger extent than in the NAc, while the reverse applied to GBR 12909 (2.5 and 5 mg/kg, i.p.). These differences were obtained in spite of the fact that the three drugs elicited at each dose level a similar peak increase of extracellular DA in the NAc. Amphetamine and cocaine also increased extracellular NA in the PFCX and this effect was quantitatively similar to that on extracellular DA in the same area. Intravenous doses of cocaine and GBR 12909, corresponding to those which maintain self-administration in the rat, while equieffective in raising extracellular DA in the NAc, had different effects on extracellular DA in the PFCX. In fact, in contrast to cocaine, GBR 12909 increased extracellular DA in the PFCX to a lesser extent than in the NAc or did not modify it at all. The peak increase of extracellular DA in the PFCX was highly correlated to that of NA in the same area but was poorly correlated to the increase of extracellular DA in the NAc. These results suggest that amphetamine and cocaine increase extracellular DA in the PFCX largely through the blockade of the NA carrier. Direct evidence for this hypothesis was provided by the observation that, when the NA carrier was blocked by reverse dialysis of the PFCX with desipramine (1 microM), cocaine and GBR 12909 lost their differences in the ability to increase extracellular DA in the PFCX.
11 Dec 1997-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a new experimental apparatus, designed principally for a high sensitivity search for ν μ → ν τ oscillation, has been successlly constructed and made operational by the CHORUS Collaboration for the CERN-WA95 experiment.
Abstract: A new experimental apparatus, designed principally for a high sensitivity search for ν μ → ν τ oscillation, has been successlly constructed and made operational by the CHORUS Collaboration for the CERN-WA95 experiment. It consists of a large emulsion target, a scintillating fiber tracker system with optoelectronics read-out, an air-core magnet, a set of trigger hodoscopes, a calorimeter based on the lead/scintillating-fiber technique, and a muon spectrometer. The design, construction and performance of the entire apparatus and of the different detectors are described.
TL;DR: In this paper, the Drell-Yan and J ψ cross-sections measured in PbPb collisions are compared with the values extrapolated from the results obtained in proton and light ion induced reactions.
TL;DR: The results of the present study indicate that the positive interaction between SCH 58261 and L-DOPA, in 6-hydroxydopamine-lesioned rats, is mainly due to an interaction with dopamine D1 receptors, and suggest that adenosine A2A receptor antagonists might be useful for potentiating the effects of L- DOPA in Parkinson's disease.
TL;DR: Lithium maintenance treatment in recurring major mood disorders has strong evidence of antisuicide effects not demonstrated with any other mood stabilizer, and close association of suicide and depression in bipolar disorder emphasizes the need for improved identification and treatment of bipolar depression.
Abstract: We reviewed evidence of a possible antisuicide action of lithium maintenance treatment in mood disorders. Of 28 published studies involving over 17,000 patients with major affective illnesses, most yielded supportive evidence: risk of suicides and attempts averaged 3.2 versus 0.37 per 100 patient-years without versus with lithium (8.6-fold difference). In a new study of 284 bipolar I- and II-disordered patients, corresponding rates (2.2 vs. 0.39/100 patient-years) differed by 5.6-fold (p < 0.001); moreover, after discontinuing lithium, rates of suicidal acts rose by 7-fold (16-fold within the first year), and fatalities increased by nearly 9-fold. Lithium maintenance treatment in recurring major mood disorders has strong evidence of antisuicide effects not demonstrated with any other mood stabilizer. Close association of suicide and depression in bipolar disorder emphasizes the need for improved identification and treatment of bipolar depression.
TL;DR: In this article, 2-chlorophenol and 2,6-dichlorophenol removal from aqueous solutions using porous carbon felt anodes was investigated. And the experimental results showed that a satisfactory detoxification, consisting of removal of cyclic chlorinated compounds, could be accomplished by means of this electrochemical method with a faradic efficiency of 30% under optimized conditions.
Abstract: Electrochemical 2-chlorophenol and 2,6-dichlorophenol removal from aqueous solutions using porous carbon felt anodes was investigated. Operating variables including current input, ratio between electrode and solution volumes, and initial pollutant concentration were considered in order to determine their influence on the faradic efficiency of the process. The byproducts of the oxidation reaction were identified, and their concentration was determined during the electrolysis. The experimental results showed that a satisfactory detoxification, consisting of removal of cyclic chlorinated compounds, could be accomplished by means of this electrochemical method with a faradic efficiency of 30% under optimized conditions. A mathematical model based on the reaction between chlorophenols adsorbed on the carbon fibers of the electrode and hydroxyl radicals produced by anodic oxidation of water has been proposed in order to interpret the experimental behavior of the system under different operating conditions.
TL;DR: A new method has been developed for quantitative, phytotherapeutic analysis with a goal to create a general tool suitable for a wide range of research situations that would allow one to gather data in such a format as to facilitate comparison with studies from other areas.
TL;DR: Methodological approaches to the study of genes conferring susceptibility to MS include association studies, which measure the frequency of a specific allele in affected and healthy populations, and linkage studies,Which trace the inheritance of a gene from parents and correlate these genes to disease susceptibility.
Abstract: The preponderance of genetic factors in attempts to account for susceptibility to multiple sclerosis (MS), a common inflammatory and demyelinating disease of young adults, has recently been demonstrated (Ebers et al . 1995). The inheritance of MS appears to be complex and is believed to involve several genes (Ebers et al . 1996; The Multiple Sclerosis Genetics Group 1996; Sawcer et al . 1996). Methodological approaches to the study of genes conferring susceptibility to MS include association studies, which measure the frequency of a specific allele in affected and healthy populations, and linkage studies, which trace the inheritance of a gene from parents and correlate these genes to disease susceptibility.
TL;DR: Data indicate that peptide expression in dorsal root ganglia and the spinal cord is markedly influenced by severe inflammation with distinct and individual temporal patterns, which are also related to the severe rearrangement of joint structure during polyarthritis.
TL;DR: Sardinian alcohol-preferring rats have been selectively bred for high ethanol preference and consumption over 16 years and 39 generations and the results suggest that voluntary ethanol intake in sP rats is sustained by the search for specific pharmacological effects of ethanol.
Abstract: Sardinian alcohol-preferring (sP) rats have been selectively bred for high ethanol preference and consumption over 16 years and 39 generations. The present paper briefly reviews some recent studies from this laboratory characterizing ethanol drinking behaviour in this rat line. Under the two-bottle regimen of free choice between 10% (v/v) ethanol and water, sP rats consume daily >4 g of ethanol/kg and avoid water almost completely. Relevant features of ethanol drinking behaviour in sP rats are: (a) attainment of high ethanol intake from the first day of exposure to ethanol, suggestive of an immediate disclosure and acquisition of ethanol reinforcement; (b) titration of daily ethanol intake in distinct binges during the nocturnal phase of the light/dark cycle, indicative of their ability to regularize both ethanol dose and administration time; (c) achievement of pharmacologically relevant blood ethanol levels at each drinking episode; (d) substitution of the calories provided by ethanol for a part of those taken from food; (e) maintenance of constant ethanol intake (in g/kg/day) in the presence of ethanol concentrations varying from 7 to 30% (v/v). These results suggest that voluntary ethanol intake in sP rats is sustained by the search for specific pharmacological effects of ethanol. Anxiolysis is likely to be one of these effects; indeed, voluntarily consumed ethanol reversed the innate, high levels of anxiety in sP rats. These results portray sP rats as a valid model for investigating the association between ethanol drinking and anxiety. Finally, the breeding programme as well as results of neurochemical studies are also described.
TL;DR: In this paper, the authors evaluate whether structural change is a key element in accounting for aggregate convergence for the Italian regions over the past two decades and conclude that aggregate convergence is largely a matter of structural change and cannot be interpreted as strong evidence in favour of the β convergence hypothesis.
TL;DR: This area seems to perform an early combination of information in the processing leading from target localization to movement generation, and for the majority of cells to a combination of visuomanual and oculomotor information.
Abstract: The role of area 7 m has been studied by recording the activity of single neurons of monkeys trained to fixate and reach toward peripheral targets. The target was randomly selected from eight possible locations on a virtual circle, of radius 30 degrees visual angle from a central target. Three tasks were employed to dissociate hand- from eye-related contributions. In the first task, animals looked and reached to the peripheral target. In a second task, the animal reached to the peripheral target while maintaining fixation on the central target. In the third task, the monkey maintained fixation on peripheral targets that were spatially coincident with those of the reaching tasks. The results show that cell activity in area 7 m relates, for some cells to eye position, for others to hand position and movement, and for the majority of cells to a combination of visuomanual and oculomotor information. This area, therefore, seems to perform an early combination of information in the processing leading from target localization to movement generation.
TL;DR: Variations in the expression of hMAF may account for the modulation in the activity of the genes that bear NFE2 recognition sites, and the association into homodimers that is induced by overexpressing hMAf inhibits theActivity of the same construct.
TL;DR: In this paper, the authors evaluated the features of MG associated with AITD compared to those of MG without thyroid disease, and found that MG was associated with mild clinical expression, with preferential ocular involvement and lower frequency of thymic disease and AchRAb.
Abstract: Myasthenia gravis (MG) may occur in association with autoimmune thyroid diseases (AITD). The aim of this study was to evaluate the features of MG associated with AITD compared to those of MG without AITD. A total of 129 MG patients (34 men and 95 women; age range, 11-81 yr) were subdivided into: group A, 56 MG patients with AITD [25 with autoimmune thyroiditis and 31 with Graves' disease (GD)]; group B, 21 MG patients with nonautoimmune thyroid diseases; and group C, 52 MG patients without thyroid disease. The severity of MG was ranked according to the Osserman score. Laboratory evaluation included assays for antithyroid and antiacetylcholine receptor (AchRAb) antibodies. Ocular MG (Osserman's class 1) was more frequent in group A (41.0%) than in group B (14.2%; P or = 2B) was more frequent in groups B (57.1%; P < 0.03) and C (51.9%; P < 0.02) than in group A (28.5%). GD patients with clinical evidence of ophthalmopathy had a higher frequency (P = 0.05) of ocular MG (57.8%) than GD patients without clinical ophthalmopathy (16.6%). Thymic disease was less frequent in group A (26.7%) than in group B (71.4%; P = 0.001) or C (59.7%; P = 0.001). The prevalence of thymic hyperplasia was 17.8%, 38.0%, and 40.3% in groups A, B, and C, respectively; the prevalence of thymoma was 8.9%, 33.4%, and 19.4%. When only patients with generalized MG were considered, thymic disease was less frequent (P < 0.02) in group A (40.6%) than in the remaining groups (69.4%). AchRAb was more frequent in groups B (57.1%) and C (57.6%; P < 0.03) than in group A (35.7%). In conclusion, MG associated with AITD has a mild clinical expression, with preferential ocular involvement and lower frequency of thymic disease and AchRAb. This supports the hypothesis that ocular and generalized MG are separate diseases with different spectra of associated diseases. Nonautoimmune thyroid diseases have no influence on the features of MG. The association of ocular MG and AITD might be due to a common autoimmune mechanism and/or a peculiar genetic background.