Showing papers by "Sapienza University of Rome published in 1986"
TL;DR: A model is proposed for the evolution of the profile of a growing interface that exhibits nontrivial relaxation patterns, and the exact dynamic scaling form obtained for a one-dimensional interface is in excellent agreement with previous numerical simulations.
Abstract: A model is proposed for the evolution of the profile of a growing interface. The deterministic growth is solved exactly, and exhibits nontrivial relaxation patterns. The stochastic version is studied by dynamic renormalization-group techniques and by mappings to Burgers's equation and to a random directed-polymer problem. The exact dynamic scaling form obtained for a one-dimensional interface is in excellent agreement with previous numerical simulations. Predictions are made for more dimensions.
4,299 citations
TL;DR: The aim of the paper is to provide first a unifying framework for the problem of schema integration, then a comparative review of the work done thus far in this area, providing a basis for identifying strengths and weaknesses of individual methodologies, as well as general guidelines for future improvements and extensions.
Abstract: One of the fundamental principles of the database approach is that a database allows a nonredundant, unified representation of all data managed in an organization. This is achieved only when methodologies are available to support integration across organizational and application boundaries.Methodologies for database design usually perform the design activity by separately producing several schemas, representing parts of the application, which are subsequently merged. Database schema integration is the activity of integrating the schemas of existing or proposed databases into a global, unified schema.The aim of the paper is to provide first a unifying framework for the problem of schema integration, then a comparative review of the work done thus far in this area. Such a framework, with the associated analysis of the existing approaches, provides a basis for identifying strengths and weaknesses of individual methodologies, as well as general guidelines for future improvements and extensions.
1,648 citations
TL;DR: A review of the method of constraints, devised to carry out Molecular Dynamics simulations of complex molecular systems with some internal degrees of freedom frozen, in terms of atomic Cartesian coordinates, and deriving the statistical-mechanical formalism for these systems.
408 citations
TL;DR: It appears, contrary to what has been repeatedly claimed in the past, the extrinsic factors are more important than the intrinsic in the aetiology of jumper’s knee.
Abstract: Jumper's knee is a typical functional overload injury because it affects those athletes who submit their knee extensor mechanisms to intense and repeated stress, e.g. volleyball and basketball players, high and long jumpers. According to the classification of Perugia and colleagues, it is an insertional tendinopathy affecting, in order of frequency, the insertion of the patellar tendon into the patella (65% of cases), attachment of the quadriceps tendon to the patella (25%) and the attachment of the patellar tendon to the tibial tuberosity (10%). The frequent occurrence of this injury in athletes led to the study of factors that may contribute to its onset and aggravation. These factors are divided into extrinsic (i.e. kind of sport practised and training methods used) and intrinsic (i.e. connected with the somatic and morphological characteristics of the athletes). On the basis of our experience and after a review of the literature it appears, contrary to what has been repeatedly claimed in the past, the extrinsic factors are more important than the intrinsic in the aetiology of jumper's knee. The effect of traumatic incidents and use of elastic kneecap guards should also be considered negligible. The intrinsic causes of jumper's knee, can be sought in the mechanical properties of tendons (resistance, elasticity and extensibility) rather than in morphological or biomechanical abnormalities of the knee extensor mechanism.
280 citations
232 citations
TL;DR: It is shown that long-term salmon CT treatment may be of benefit in postmenopausal osteoporosis and that the effects of CT on bone mass may be due not only to the inhibition of bone resorption but also to the stimulation of bone formation.
Abstract: In this paper we present the results of a 12-month double-blind clinical multicenter study assessing the effects of synthetic salmon cacitonin (CT) administration in a group of white postmenopausal osteoporotic women. Treated patients were given 100 MRC units of synthetic salmon CT injected i.m. in the morning every other day. Control patients received a placebo injection. All patients received 500 mg of elementary calcium p.o., b.i.d. Bone mineral content (BMC) was measured at the extreme distal radius of the nondominant arm by a dual photon bone densitometer which utilizes two radionuclides,241Am and125I, with energies of about 60 keV and 30 keV respectively. Biochemical parameters of calcium-phosphorus metabolism were also measured. After 12 months of treatment a significant mean increment of BMC and nondialyzable OHPr/creatinine values and a significant decrease of total OHPr/creatinine values were observed in the treated group, while controls showed a significant decrease in BMC values. These results, together with the observation that in some patients the decrease in total OHPr/creatinine values was not accompanied by an increment of BMC, show that long-term salmon CT treatment may be of benefit in postmenopausal osteoporosis and that the effects of CT on bone mass may be due not only to the inhibition of bone resorption but also to the stimulation of bone formation.
196 citations
TL;DR: In this article, a search to observe neutrino decays has been performed, and its results are used to set limits on the couplings of a hypothetical massive Neutrino with the ordinary ve and vμ.
196 citations
TL;DR: The Dissipation-Rumination Scale as discussed by the authors is related to the inclination to overcome and abandon more or less rapidly feelings of distress and wishes of retaliation associated with the experience of insults suffered.
179 citations
TL;DR: The field of intramolecular reactions is a mature area in which the merging of concepts from both physical organic chemistry and polymer chemistry leads to a unified treatment of cyclization rates and equilibria in terms of a few simple generalizations and theories as discussed by the authors.
Abstract: Publisher Summary This chapter focuses that the field of intramolecular reactions is a mature area in which the merging of concepts from both physical organic chemistry and polymer chemistry leads to a unified treatment of cyclization rates and equilibria in terms of a few simple generalizations and theories. It is concerned with reaction rates, equilibria, and mechanisms of cyclization reactions of chain molecules. It discusses that parallel to the search for synthetic methods to make rings of all sizes, kinetic studies have appeared with the aim of providing insight into physical aspects of ring closure. A significant portion of the evidence available on the kinetics of intramolecular reactions falls in the domain of neighboring group participation. The term is sufficiently wide to encompass “all intramolecular reactions and all reactions that involve nonelectrostatic through-space interactions between groups in the same molecule.” However, the most common types of neighboring group participation involve nucleophilic participation either with or without anchimeric assistance and intramolecular acid and base catalysis. The chapter explores that intramolecular catalysis phenomena have attracted much attention, both from the experimental and theoretical points of view, not only on account of their inherent mechanistic interest, but also because they are believed to model the extraordinary efficiency of enzyme catalysis.
179 citations
TL;DR: The genetic variation of the sibling species Anisakis simplex A and A. simplex B was investigated by electrophoretic analysis of 22 gene-enzyme systems and several paratenic hosts and one cetacean definitive host are identified for each of the two species.
164 citations
TL;DR: In this paper, the energy extent of the type-II multiple-scattering (MS) regime was determined by making a comparison between the Mn K-edge absorption of (${\mathrm{MnO}}_{4}$${) and [Mn${H}}_{2}$O${)}_{6}$ ] 2+}$ complexes in aqueous solution.
Abstract: By making a comparison between the Mn K-edge absorption of (${\mathrm{MnO}}_{4}$${)}^{\mathrm{\ensuremath{-}}}$ and [Mn(${\mathrm{H}}_{2}$O${)}_{6}$${]}^{2+}$ complexes in aqueous solution we obtain an experimental determination of the energy extent of the type-II multiple-scattering (MS) regime that is substantially wider than expected. Theoretical calculations based on the MS formalism support this conclusion. We also recognize three energy regions in the absorption spectra of these complexes: a full MS region, where numerous or an infinite number of MS paths of high order contribute (depending on whether the MS series converges or not), an intermediate MS region, where only a few MS paths of low order are relevant, and a single-scattering region where the photoelectron is backscattered only once by the ligands [extended x-ray-absorption fine-structure (EXAFS) regime]. Theoretical considerations show that this must be a general situation in x-ray-absorption spectra and opens the way to a unified scheme for their interpretation. The energy extent of the three regions is obviously system dependent. We also show how to generalize to MS contributions the usual EXAFS analysis using curved-wave propagators and indicate how to extract geometrical information from the spectra of the two clusters investigated. In particular the method is used to derive the Mn---O---O---Mn path length in the (${\mathrm{MnO}}_{4}$${)}^{\mathrm{\ensuremath{-}}}$ complex.
TL;DR: A layout algorithm is presented that allows the automatic drawing of data flow diagrams, a diagrammatic representation widely used in the functional analysis of information systems.
Abstract: A layout algorithm is presented that allows the automatic drawing of data flow diagrams, a diagrammatic representation widely used in the functional analysis of information systems. A grid standard is defined for such diagrams, and aesthetics for good readability are identified. The layout algorithm receives as input an abstract graph specifying connectivity relations between the elements of the diagram, and produces as output a corresponding diagram according to the aesthetics. The basic strategy is to build incrementally the layout; first, a good topology is constructed with few crossings between edges; subsequently, the shape of the diagram is determined in terms of angles appearing along edges. and finally dimensions are given to the graph, obtaining a grid skeleton for the diagram.
TL;DR: In this paper, the authors point out that the field theoretical description of the localisation transition exhibits anomalous scaling for the moments of the probability density at the localization threshold, which hints at a multifractal structure of the wavefunction.
Abstract: The authors point out that the field theoretical description of the localisation transition exhibits anomalous scaling for the moments of the probability density at the localisation threshold. This property hints at a multifractal structure of the wavefunction. They attempt an analysis of the corresponding singularity distribution.
TL;DR: Observations suggest that in early mammalian development homoeobox genes may exert a wide spectrum of control functions in a variety of organs and body parts, in addition to the spinal cord, in a striking organ- and stage-specific pattern.
Abstract: The homoeobox is a 183 base-pair (bp) DNA sequence1 conserved in several Drosophila genes controlling segmentation and segment identity2–4. Homoeobox sequences have been detected in the genome of species ranging from insects and anellids to vertebrates5,6 and homoeobox containing genes have been cloned from Xenopus7–9, mouse10–22 and man23. We recently isolated human homoeobox containing complementary DNA clones, that represent transcripts from four different human genes24. One clone (HHO.c10) is selectively expressed in a 2.1 kilobase (kb) polyadenylated transcript in the spinal cord of human embryos and fetuses 5–10 weeks after fertilization25. We report the characterization of a second cDNA clone, termed HHO.c13, that represents a new homoeobox gene. This clone encodes a protein of 255 amino-acid residues, which includes a pentapeptide, upstream of the homoeo domain, conserved in other Drosophila, Xenopus, murine and human homoeobox genes. By Northern analysis HHO.c13 detects multiple embryonic transcripts, which are differentially expressed in spinal cord, brain, backbone rudiments, limb buds and heart in 5–9-week-old human embryos and fetuses, in a striking organ- and stage-specific pattern. These observations suggest that in early mammalian development homoeobox genes may exert a wide spectrum of control functions in a variety of organs and body parts, in addition to the spinal cord.
TL;DR: The analysis of human and animal bones excavated from the Neolithic levels of the Fontbr�goua Cave strongly suggests that humans were butchered, processed, and probably eaten in a manner that closely parallels the treatment of wild and domestic animals at Fontbrb� goua.
Abstract: Cannibalism is a provocative interpretation put forth repeatedly for practices at various prehistoric sites, yet it has been so poorly supported by objective evidence that later, more critical reviews almost invariably reject the proposal. The basic data essential to a rigorous assessment of a cannibalism hypothesis include precise contextual information, analysis of postcranial and cranial remains of humans and animals, and detailed bone modification studies. Such data are available from the Neolithic levels of the Fontbregoua Cave (southeastern France) where several clusters of human and animal bones have been excavated. The analysis of these bones strongly suggests that humans were butchered, processed, and probably eaten in a manner that closely parallels the treatment of wild and domestic animals at Fontbrbegoua.
TL;DR: The modulation of intracellular calcium concentrations by calcium ionophores induced Epstein-Barr viral antigens in lymphoblastoid cell lines that carry the virus.
Abstract: In many viral infections the host cell carries the viral genome without producing viral particles, a phenomenon known as viral latency. The cellular mechanisms by which viral latency is maintained or viral replication is induced are not known. The modulation of intracellular calcium concentrations by calcium ionophores induced Epstein-Barr viral antigens in lymphoblastoid cell lines that carry the virus. When calcium ionophores were used in conjunction with direct activators of protein kinase C (12-O-tetradecanoyl phorbol-13-acetate and a synthetic diacylglycerol), a greater induction of viral antigens was observed than with either agent alone. Activation of protein kinase C may be required for the expression of the viral genome.
TL;DR: In this article, a viscous incompressible fluid moving in a two-dimensional flat torus is studied and a set of external forces for which the stationary state is attractive for any Reynolds number is given.
Abstract: We study a viscous incompressible fluid moving in a two dimensional flat torus [0,L] × [0,2π],L<2π. We show a set of external forces for which the stationary state is attractive for any Reynolds numberR. Moreover, the size of this set and the basin of attraction are independent ofR.
TL;DR: It is demonstrated that bile salts hydrophilicity influences the quantity of phosphatidylcholine in bile but not the quality, as well as the type of conjugation.
Abstract: Bile salts and phospholipids from bile of chicken, dog, sheep, rat, ox, pig, guinea-pig and man were analyzed by high-performance liquid chromatography. Bile salts showed marked differences in their hydrophilic properties, owing to hydroxyl structure and type of conjugation. Phospholipids were generally similar, containing 90-95% of phosphatidylcholine which was made of molecular species containing palmitic acid in the sn-1 position. The comparative analysis of bile salts and phosphatidylcholines profile demonstrated that bile salts hydrophilicity influences the quantity of phosphatidylcholine in bile but not the quality.
TL;DR: Genetic analysis of the founder stock and five subsequent hatchery generations revealed a constant reduction in levels of allozyme polymorphism, which pointed out the importance of a careful check of the number of spawners actually contributing to each reproductive cycle.
TL;DR: Doplicher and Longo as discussed by the authors extended the construction of local generators of symmetries to space-time and supersymmetries, and established a weak form of Noether's theorem in quantum field theory.
TL;DR: In this paper, the theory of public goods is applied to the problem of wage price stability, and empirical verification of this proposition is attempted in cross-country comparisons by constructing indices of neocorporatism, which are then found to be negatively related to Okun's "misery index" in various industrialized countries.
Abstract: In this paper, the theory of public goods is applied to the problem of wage price stability. In the first part, it will be argued that achievable levels of inflation and employment vary directly with both the degree of centralization of a country’s system of collective bargaining and the degree of consensus governing both the distribution of income and the acceptability of the government in power. In the second part, empirical verification of this proposition is attempted in cross-country comparisons by constructing indices of neocorporatism, which are then found to be negatively related to Okun’s ’misery index’ in various industrialized countries.
TL;DR: In this paper, the concept of the distribution function of a closed-valued measurable multifunction is introduced and used to study the convergence of sequences of multifunctions and the epi-convergence in distribution of normal integrands and stochastic processes; in particular various compactness criteria are exhibited.
Abstract: The concept of the distribution function of a closed-valued measurable multifunction is introduced and used to study the convergence in distribution of sequences of multifunctions and the epi-convergence in distribution of normal integrands and stochastic processes; in particular various compactness criteria are exhibited. The connections with the classical convergence theory for stochastic processes are analyzed and for purposes of illustration we apply the theory to sketch out a modified derivation of Donsker's Theorem Brownian motion as a limit of normalized random walks. We also suggest the potential application of the theory to the study of the convergence of stochastic infima.
TL;DR: The no-information interpretation of null values is adopted, and three types of constraints on null values are taken into account, and the interaction of each of them with functional dependencies is studied.
Abstract: Database relations with incomplete information are considered. The no-information interpretation of null values is adopted, due to its characteristics of generality and naturalness. Coherently with the framework and its motivation, two meaningful classes of integrity constraints are studied: (a) functional dependencies, which have been widely investigated in the classical relational theory and (b) constraints on null values, which control the presence of nulls in the relations. Specifically, three types of constraints on null values are taken into account (nullfree subschemes, existence constraints, disjunctive existence constraints), and the interaction of each of them with functional dependencies is studied. In each of the three cases, the inference problem is solved, the complexity of the algorithms for its solution analyzed, and the existence of a complete axiomatization discussed.
TL;DR: This work uses recent results on the spin glass mean field theories to show that this completion of Hopfield's memory model can be done in a natural way with a minimal modification of Hebb’s rule for learning.
Abstract: In the original formulation of Hopfield's memory model, the learning rule setting the interaction strengths is best suited for orthogonal words. From the point of view of categorization, this feature is not convenient unless we reinterpret these words as primordial categories. But then one has to complete the model so as to be able to store a full hierarchical tree of categories embodying subcategories and so on. We use recent results on the spin glass mean field theories to show that this completion can be done in a natural way with a minimal modification of Hebb's rule for learning. Categorization emerges naturally from an encoding stage structured in layers.
TL;DR: The particular importance of the continuous hydroxyurea administration modality clearly emerges, suggesting the use of different administration modalities to reduce such serious side effects.
Abstract: The unusual appearance of extensive skin ulcerations was observed in 17 patients with chronic myelogenous leukemia on continuous chemotherapy with hydroxyurea. The strict relationship between ulcers and therapy was proved by the complete (14 cases) or almost complete (3 cases) healing of lesions after therapy was discontinued. The possible pathogenetic mechanisms responsible for skin alterations are considered. The particular importance of the continuous hydroxyurea administration modality clearly emerges, suggesting the use of different administration modalities to reduce such serious side effects.
TL;DR: These results are qualitatively consistent with the onset of a surface-roughening transition, in agreement with recent experimental results obtained from helium scattering on (110)copper surfaces.
Abstract: The thermodynamical and structural behavior of a (110) face of a fcc (12-6) Lennard-Jones solid has been investigated by molecular-dynamics simulation on the solid-gas coexistence line. The temperature dependence of the relevant structural and mass-transport properties shows the following. (a) Despite the high degree of disorder which gradually appears on surface layers when the temperature is increased, the surface retains its solidlike character up to temperatures (T\ensuremath{\approxeq}0.64\ensuremath{\varepsilon}/${k}_{B}$) very close to the triple point (${T}_{t}$=0.68\ensuremath{\varepsilon}/${k}_{B}$). This conclusion does not confirm the findings of previous theoretical work predicting the formation of a liquid surface layer well below the bulk melting point. (b) The large concentration of vacancy-adatom pairs, produced at the surface in the high-temperature range, accounts for the high values of the surface diffusivity. (c) The Arrhenius plot of defect concentration indicates a progressive decrease of their formation energy for temperatures ranging from ${T}_{r}$=0.8${T}_{m}$ to the melting point. Consistently, the order parameter decreases slowly with increasing temperature up to ${T}_{r}$ but from T=${T}_{r}$ to the melting point it decreases much more rapidly than predicted by the extrapolation of the low-temperature data. These results are qualitatively consistent with the onset of a surface-roughening transition, in agreement with recent experimental results obtained from helium scattering on (110) copper surfaces.
TL;DR: The ionic strength dependences of the binding of tetrakis to poly(dG-dC) and calf thymus DNA and the avidity of binding does decrease with increasing [Na+] as predicted, but of greater interest is the relocation of the porphyrin from GC-rich regions to AT- rich regions as the ionsic strength increases.
Abstract: The ionic strength dependences of the binding of tetrakis (4-N-methylpyridyl)porphine (H2TMpyP) to poly(dG-dC) and calf thymus DNA have been determined. For the former system the results are typical of other intercalators, i.e., a plot of log K vs log [Na+] is linear albeit with a slope which suggests that the "effective charge" of the porphyrin is closer to two than the formal charge of +4. For calf thymus DNA, the binding profile is not completely compatible with the predictions of condensation theory. Whereas the avidity of binding does decrease with increasing [Na+] as predicted, of greater interest is the relocation of the porphyrin from GC-rich regions to AT-rich regions as the ionic strength increases.
TL;DR: A new continuously differentiable exact penalty function is introduced for the solution of nonlinear programming problems with compact feasible set that is defined on a suitable bounded open set containing the feasible region and that it goes to infinity on the boundary of this set.
Abstract: In this paper a new continuously differentiable exact penalty function is introduced for the solution of nonlinear programming problems with compact feasible set A distinguishing feature of the penalty function is that it is defined on a suitable bounded open set containing the feasible region and that it goes to infinity on the boundary of this set This allows the construction of an implementable unconstrained minimization algorithm, whose global convergence towards Kuhn-Tucker points of the constrained problem can be established
TL;DR: Polyacrylamide-gel electrophoresis and specific-activity data indicate that diamine oxidase is the most plentiful protein in the extracellular solution obtained from pea epicotyl sections and that an active process is involved in the selective transfer of the enzyme outside the cell.
Abstract: Most of the diamine oxidase (EC 1.4.3.6) present in pea (Pisum sativum L. cv. Rondo) epicotyls is found in the fluid obtained by centrifuging pea epicotyl sections previously infiltrated under vacuum with a buffer solution. No detectable amount of the cytoplasmic enzyme glucose-6-phosphate dehydrogenase is present in this fluid, showing that there is very little contamination by cell contents. Polyacrylamide-gel electrophoresis and specific-activity data indicate that diamine oxidase is the most plentiful protein in the extracellular solution obtained from pea epicotyl sections and that an active process is involved in the selective transfer of the enzyme outside the cell. The possible involvement of diamine oxidase in the supply of H2O2 to peroxidase-catalyzed reactions occurring inside the cell wall is discussed.
TL;DR: It is concluded that in Parkinson's disease the disability in generating two joint ballistic movements depends on a difficulty in running motor programmes for complex trajectories.
Abstract: Fast arm movements involving the shoulder and elbow joints have been analysed in normal controls and in patients with Parkinson's disease. The subjects were requested to draw on a graphic tablet triangles and squares of different size and shape. The patients produced a larger number of EMG burst compared with controls. The movements were accurate, and each segment of the geometric figures was performed with a roughly straight trajectory, but the time necessary to trace the geometric figures and the pauses at the vertices were prolonged. We conclude that in Parkinson's disease the disability in generating two joint ballistic movements depends on a difficulty in running motor programmes for complex trajectories.