Showing papers by "University of Trento published in 1988"

An interactive multi-user decision support system for consensus reaching processes using fuzzy logic with linguistic quantifiers

Abstract: We present an interactive user-friendly microcomputer-based decision support system for consensus reaching processes. The point of departure is a group of individuals (experts, decision makers,…) who present their testimonies (opinions) in the form of individual fuzzy preference relations. Initially, these opinions are usually quite different, i.e., the group is far from consensus. Then, in a multistage session a moderator, who is supervising the session, tries to make the individuals change their testimonies by, e.g., rational argument, bargaining, etc. to eventually get closer to consensus. For gauging and monitoring the process a new ‘soft’ degree (measure) of consensus is used whose essence is the determination to what degree, e.g., ‘most of the individuals agree as to almost all of the relevant options’. A fuzzy-logic-based calculus of linguistically quantified propositions is employed.

Risk factors for hepatocellular carcinoma in northern Italy.

Abstract: The role of socio-demographic factors, lifestyle habits and selected dietary factors on the risk of hepatocellular carcinoma was evaluated in a hospital-based case-control study conducted in Northern Italy on 151 patients with hepatocellular carcinoma and 1,051 controls in hospital for acute, non-neoplastic or digestive conditions, unrelated to any of the known or potential risk factors for primary liver cancer. There were significant inverse relationships with levels of education and social class (relative risk, RR = 1.9 and 2.4 for lower vs. upper categories), and positive associations with clinical history of hepatitis (RR = 3.5, 95% confidence interval = 2.0-6.0) or liver cirrhosis (RR = 15.6, 95% CI = 8.3-29.4). The relative risk was not elevated in smokers and light or moderate alcohol drinkers, but the point estimate was above unity among heavy drinkers (RR = 1.5, 95% CI = 1.0-2.4). Among 14 food items considered, including important sources of vitamin A, protein and fats in the Italian diet, 5 were inversely and significantly related to liver cancer risk. This suggests that a diet deficient in several aspects may be related to hepatocellular carcinoma.

The Temporal Dimension in Organizational Studies

Abstract: Organization studies and theories are based on time-free statements. This paper introduces the concept of 'organizational time' in order to explore the internal and particular time of the individual organization (or event) and the time involved in intra-organizational dynamics in relation to other times. Two research studies prompted the authors' reflections on organizational time as an important variable in the shaping of the scenario of decision-making processes. It is argued that the heuristic validity of the variable 'organizational time' lies in the interpretation of the choices and culture of organizational actors and in their defining of the boundaries of the organization.

The Return to the State: Critiques

Abstract: This symposium features three critiques of Gabriel Almonds argument—by Eric A. Nordlinger of Brown University, Theodore J. Lowi of Cornell University, and Sergio Fabbrini of the University of Trento.

Ion modulation of membrane permeability: effect of cations on intact cells and on cells and phospholipid bilayers treated with pore-forming agents.

Abstract: Leakage of ions (Na+, K+) and phosphorylated metabolites (phosphorylcholine, 2-deoxyglucose 6-phosphate) through membrane lesions in intact cells or in cells modified by ‘pore-forming’ agent has been studied. Leakage from intact cells isinduced by protons and by divalent cations such as Cu2+, Cd2+ or Zn2+. Leakage from agent-modified cells—or across phospholipid bilayers modified by agent—isprevented by low concentrations of the same cations and by higher concentrations of Ca2+, Mn2+ or Ba2+; Mg2+, dimethonium, spermine, or spermidine are virtually ineffective. The relative efficacy of a particular cation (e.g. Ca2+) depends more on cell type than on the nature of the pore-forming agent. The predominant effect is on binding of cation to specific sites, not on surface charge. Surface charge, on the other hand, does affect leakage from agent-modified cells in that suspension in nonionic media reduces leakage, which can be restored by increasing the ionic strength: univalent (Na+, K+, Rb+, NH 4 + ) and divalent (Mg2+, dimethonium) cations are equally effective; addition of protons or divalent cations such as Zn2+ to this system inhibits leakage. From this and other evidence here presented it is concluded that leakage across membranes is modulated by the presence of endogenous anionic components: when these are in the ionized state, leakage is favored; when unionized (as a result of protonation) or chelated (by binding to divalent cation), leakage is prevented. It is suggested that such groups are exposed at the extracellular face of the plasma membrane.

Isolation from the Mediterranean Stolonifern Coral Sarcodictyon roseum of Sarcodictyin C, D, E, and F, novel diterpenodic alcohols esterified by (E)‐ or (Z)‐N(1)‐methylurocanic acid. Failure of the carbon‐skeleton type as a classification criterion

Abstract: It is shown here that the stoloniferan coral Sarcodictyon roseum of east Pyrenean waters contains four novel diterpenoids, sarcodictyin C ((−)-3), D ((−)-4), E ((+)-5), F ((+)-6), which are related to sarcodictyin A ( = (−)-(4R,4aR,7R,10S,11S,12aR,1Z,5E,8Z-7,10-epoxy-3,4,4a,7,10,11,12,12a-octahydro-7-hydroxy-6-(methyoxycarbonyl)-1,10-dimethyl-4-(1-methylethyl)-benzocyclodecen-11-yl (E)-N1-methylyrocanate; ((−)−1), previously isolated from the same coral. Sarcodictyin C ((−)-3) and D ((−)-4) and the 3α-hydroxy and 3α-acetoxy derivatives of (−)-1), sarcodictyin E ((+)-5) is the (Z)-urocanate isomer of (−)-3), and sarcodictyin F ((+)-6) is the 1α-hydroxy-2-ene isomer of (−)-3. In all cases, the nine-membered ring is locked, and the molecule stabilized, by the urocanic appendage; when this is removed in MeOH/KOH, the C(11)–O− function is free to attack at C(5), and retro-condensations then lead to the ring-contracted butenolides 11 (from (−)-3) or 10 (from(−)-1) with extrusion of the hydroxyfuran nucleus (Scheme 3). Under the same conditions, with (−)-3, the C(3)-O− group competitively attacks at C(5), the hydroxyfuran nucleus is expelled, and aldehyde 14 is formed. Peculiarly, in the reaction of (−)-3 with MeOD/KOD, the ring-contracted butenolide 17 contains D at the 4′-ax position. The sarcodictyins are unique in these chemical properties, not shared by the cladiellanes which have the same C-skeleton.

The hemolysin of Escherichia coli.

Abstract: Many strains of E coli elaborate a hemolysin which is responsible for the zone of β-hemolysis surrounding bacterial colonies on blood agar The significance of this cytolysin as a determinant of bacterial pathogenicity has been established in animal models with the use of genetically engineered, isogenic bacterial strains An analogous role in human infections has been inferred from the high association of hemolysin production with disease Studies at a molecular genetical level have defined 4 genes that are required for the synthesis, post,translational modification and secretion of the hemolysin The structural gene hlyA encodes for a 107-110 000 polypeptide, which must be modified in an unknown manner to its active form by the product of the neighboring hlyC gene Genes hlyb and hlyD encode for proteins that export the molecule to the extracellular medium The signal for secretion is contained in the C-terminal portion of the toxin molecule The secreted hemolysin attacks plasma membranes of target mammalian cells by inserting as a monomer into the bilayer and generating hydrophilic transmembrane pores of approximately 2 nm effective diameter The pores display a marked selectivity for cations over anions and pore-opening is dependent on the presence of a correct transmembrane potential Binding to a membrane target does not require the presence of a specific receptor, and pores may be generated in planar lipid membranes consisting solely of phosphatidylcholine Pore formation in nucleated cells can trigger secondary reactions such as stimulation of arachidonate metabolism with release of lipid mediators, probably initiated by passive influx of extracellular Ca2+ Perfusion of subcytolytic doses through isolated and ventilated rabbit lungs induces lung edema that is at least partially due to such secondary events The capacity of E coli hemolysin to damage human tissues via primary and secondary processes is consistent with the concept of its pathogenic role in human infections[/p]

Novel Aplysinopsin‐Type Alkaloids from Scleractinian Corals of the Family Dendrophylliidae of the Mediterranean and the Philippines. Configurational‐assignment criteria, stereospecific synthesis, and photoisomerization

Abstract: From the scleractinian coral Tubastraea sp. (Dendrophylliidae) collected at Palawan, Philippines, 3′-deimino-3′-oxoaplysinopsin (4) and 6-bromo-3′-deimino-3′-oxoaplysinopsin (6) are now isolated as 5:2 mixtures of (E/Z) stereoisomers. The 3′-deimino-2′,4′-bis(demethyl)-3′-oxoaplysinopsin (7) and 6-bromo-3′-demino-2′,4-bis(demethyl)-3′-oxoaplysinopsin (5) are isolated as 2:3 and 1:1 (E/Z) mixtures, respectively, from another dendrophylliid, Leptopsammia pruvoti, collected near Marseille, Mediterranean coast of France. Larger amounts of these and related compounds, needed for a full structural determination, are obtained by synthesis. Thus, condensations of indol-3-carboxaldehyde (9) or of its 6-bromo derivative 14 with hydantoin (15), 3-methylhydantoin (11), or 1,3dimethylhydantoin (10) give the prevalent natural aplysinopsins with high stereospecificity. The minor stereoisomers (Z)-4, (Z)-6, (E)-7, and (E)-5 are obtained by (E/Z) photoisomerization under UV light of the condensation mixtures. The configuration is assigned from larger HC(8)/C(5′) 1H, 13C couplings in the (E) than in the (Z) isomer, and, in the case of 4 and 6, from NOE enhancement at MeN(2′) on irradiation at HC(8). The stereospecificity of the condensations is attributed to steric inhibition to planarity in the rate-limiting transition states, due to N(2′)/HC(2) repulsion with (Z)-4 and (Z)-6, or to C(5′)O/HC(2) repulsion with (E)–7 or (E)-5. As the aplysinopsins undergo (E/Z ) phostoisomerization also under the daylight conditions of the laboratory, their isomeric composition in nature can not be presently assessed.

Low-Energy Raman Scattering from Silver Particles in Alkali Halides

Abstract: Raman spectra of silver particles in NaCl and KI are reported, which show the particles to have spheroidal shape and undergo quadrupolar surface vibrations. From the energies of the observed modes the shape and dimension of the metallic particles are deduced.

On Measuring Consensus in the Setting of Fuzzy Preference Relations

Abstract: Consensus, traditionally understood as a full and unanimous agreement, is a utopia in virtually all practical cases. A degree of consensus to indicate how far one is from complete agreement does therefore make sense. We present a ‘soft’ consensus measure which is basically a degree to which, say, “most pairs of individuals agree as to their preferences between almost all relevant options”. The point of departure is the set of individual preference relations. A fuzzy-logic-based calculus of linguistically quantified proposition is employed.

Loop space representation of quantum general relativity

Abstract: We define a new representation for quantum general relativity, in which exact solutions of the quantum constraints may be obtained. The representation is constructed by means of a noncanonical graded Poisson algebra of classical observables, defined in terms of Ashtekar's new variables. The observables in this algebra are nonlocal and involve parallel transport around loops in a three-manifold Σ. The theory is quantized by constructing a linear representation of a deformation of this algebra. This representation is given in terms of an algebra of linear operators defined on a state space which consists of functionals of sets of loops in Σ. The construction is general and can be applied also to Yang-Mills theories. The diffeomorphism constraint is defined in terms of a natural representation of the diffeomorphism group. The hamiltonian constraint, which contains the dynamics of quantum gravity, is constructed as a limit of a sequence of observables which incorporates a regularization prescription. We give the general solution of the diffeomorphism constraint in closed form. It is spanned by a countable basis which is in one-to-one correspondence with the diffeomorphism equivalence classes of multiple loops, which are a generalization of the link classes studied in knot theory. Then we explicitly construct, in closed form, a large space of solution of the entire set of constraints, including the hamiltonian constraint. These turn out to be classified by the ordinary knot and link classes of Σ. The space of solutions that we find is a sector of the physical states space of nonperturbative quantum general relativity. The failure of perturbation theory is thus shown to be not relevant to the problem of the existence of a nontrivial physical state space in quantum gravity. The relationship between this new loop representation and the self-dual representation of Ashtekar is illuminated by means of a functional transform between states in the two representations. Questions of the completeness of the solution space, the meaning of the physical operators and the physical inner product, are discussed, but not, so far, resolved.

Singular convergence of weak solutions for a quasilinear nonhomogeneous hyperbolic system

Abstract: We show that the weak solutions of the nonlinear hyperbolic system $$\left\{ \begin{gathered} \varepsilon u_t^\varepsilon + p(v^\varepsilon )_x = u^\varepsilon \hfill \\ v_t^\varepsilon - u_x^\varepsilon = 0 \hfill \\ \end{gathered} \right.$$ converge, as e tends to zero, to the solutions of the reduced problem $$\left\{ \begin{gathered} u + p(v)_x = 0 \hfill \\ v_t - u_x = 0 \hfill \\ \end{gathered} \right.$$ . Then they satisfy the nonlinear parabolic equation $$v_t + p(v)_{XX} = 0$$ . The limiting procedure is carried out using the techniques of “Compensated Compactness”. Some connections with the theory of nonlinear heat conduction and the theory of nonlinear diffusion in a porous medium are suggested. The main result is stated in th. (2.9).

Dragging of inertial frames by the rotating Earth: Proposal and feasibility for a ground-based detection

Abstract: We are proposing a ground-based experiment to detect the Lense-Thirring drag due to the rotating earth by an off-line comparison between an astrometric measurement of the Earth rotation and an inertial measurement of the angular velocity of the laboratory. It is shown that the former, by means of routine observations of Very Long Baseline Interferometry, has already reached the accuracy needed to perform a 3 % experiment on a time span of ∼1 yr. We propose to perform the latter by a dynamical detector of local rotation of novel conception, the Gyromagnetic Electron Gyroscope. Its principle of operation is briefly discussed together with its response to rotationlike gravitational fields.

Dendryphiellin A, the First Fungal Trinor‐eremophilane. Isolation from the marine deuteromycete Dendryphiella salina (SUTHERLAND) PUGHet NICOT

Abstract: The novel metabolite dendryphiellin A ( = (+)-(1R,2S,8aR)- 1,2,6,7,8,8a-hexahydro-7-hydroxy-1,8a-dimethyl-6-oxonaphthalen-2-yl (6R*, 2E,4E)-8-hydroxy-6-methylocta-2,4-dienoate; (+)-1) is isolated from cultures of the marine deuteromycete Dendryphiella salina. There is no precedent in fungi for trinor-eremophilanes or for branched C9 carboxylic acids, the two classes of compounds constituting (+)-1. The structure is secured by NMR spectroscopy and hydrolysis of (+)-1 to give the side-chain moiety ((6R*,2E,4E)-8-hydroxy-6-methylocta-2,4-dienoic acid (2)) intact, whilst the trinor-ermophilane moiety is decomposed. The absolute configuration at the trinor-eremophilane moiety is established from exciton coupling between the dienone and the diene-ester functions.

Asymptotic behaviour of the density for one-dimensional Navier-Stokes equations

Abstract: The existence of a (global in time) solution to the Navier-Stokes equations for barotropic compressible fluids in a bounded interval is already known in the case of vanishing external force field. In this paper we consider these equations for time-independent forces and prove that: (i) there exists a global solution to the usual initial-boundary value problem; (ii) the density of the fluid is bounded and its infimum is greater than zero for infinite time only if the external forces and the pressure satisfy a compatibility condition (which is the same derived in [2] for the existence of a stationary solution having bounded and strictly positive density).

Characterization of surface layers in ion-nitrided titanium and titanium alloys

Abstract: Surface layers having elevated hardness were produced by ion nitriding of titanium and α-β alloys of Ti-6wt.%Al-4wt.%V, Ti-4wt.%Al-2wt.%Sn4wt.%Mo and Ti-4wt.%Al-2wt.%Mn. The treatment was conducted at temperatures between 1073 and 1273 K for times of 4–32 h, using gaseous mixtures of nitrogen and hydrogen containing 20–80 vol.% nitrogen. X-ray diffraction, optical microscopy and microhardness were used to characterize the hardened surfaces. In most of the samples, this surface was composed of the phases δ (TiN type), ϵ (Ti 2 N type) and α (solid solution of nitrogen in titanium); in other cases only the δ and α phases were present. The operating parameters which influence the composition of the layer were identified and the particular crystalline texture of the ϵ phase is discussed.

Vibrational deactivation mechanisms for O+2(v=1) colliding with Kr

Abstract: The dynamics of the Kr–O+2(v=1) deexcitation process has been investigated in detail by performing classical trajectory calculations and related graphical studies. The consequence of the trapping at the chemical well, the nature of the intermediate complex, and the effect of reaching turning points have been examined for these atom‐charged diatom collisions. The impact of all that on the modeling of the quenching process has also been discussed.

Slowly interconverting conformers of the briarane diterpenoids verecynarmin B, C, and D, isolated from the nudibranch mollusc Armina maculata and the pennatulacean octocoral Veretillum cynomorium of East Pyrenean waters

Abstract: The novel briarane diterpenoids verecynarmin B(=(−)-(1R*, 10S*, 11R*, 4E, 12Z)-briara-4,7,12,17,-tetraen-14-one; (−)-4); verecynarmin C (=(−)-(1R*, 10R*, 11S*, 4E, 12Z)−11-hydroxybriara-4,7,12,17-tetraen-14-one; (−)-5); and verecynarmin D (=(−)-(1R*, 10R*, 11R*, 4E, 12E)-13-chloro-11-hydroxybriara-4,7,12,17,-tetraen-14-one; (−)-6) are reported here as constituents of both the Mediterranean nudibranch mollusc Armina maculata (Rafinesque) and its prey, the pennatulacean octocoral Veretillum cynomorium (PALLAS). The structural assignments rest mainly on (i) establishing that these briaranes occur in solution as two stable conformers which interconvert slowly (ca. 10 time per second at r.t. according to dynamic NMR) by 180° flipping of the C(4)C(5) group in the ten-membered ring (Scheme 1), (ii) deriving, for both conformers, 1H, 1H coupling constants from 1D spectra, as well as 1H, 1H, 13C, 1H, and 13C, 1H, and 13C, 13C, correlations from 2D experiments; (iii) subjecting the briaranes to SeO2 oxidation at the C(16) methyl group with isomerization at the C(4)=C(5) bond to give, in each case, only one observable molecular species as shown by NMR spectroscopy (Scheme 2).