Search results for "Formula"
showing 10 items of 755 documents
Structure and Dynamics of the Instantaneous Water/Vapor Interface Revisited by Path-Integral and Ab Initio Molecular Dynamics Simulations
2015
The structure and dynamics of the water/vapor interface is revisited by means of path-integral and second-generation Car-Parrinello ab-initio molecular dynamics simulations in conjunction with an instantaneous surface definition [A. P. Willard and D. Chandler, J. Phys. Chem. B 114, 1954 (2010)]. In agreement with previous studies, we find that one of the OH bonds of the water molecules in the topmost layer is pointing out of the water into the vapor phase, while the orientation of the underlying layer is reversed. Therebetween, an additional water layer is detected, where the molecules are aligned parallel to the instantaneous water surface.
World revision of the genus Encyrtoscelio Dodd (Hymenoptera: Scelionidae)
1995
The genus Encyrtoscelio Dodd is revised. E. apterus (Szelényi), E. mirissimus Dodd, E. turneri Waterston are redescribed, and six new species are described: E. cydni Caleca, E. japonicus Caleca, E. mediterraneus Caleca, E. miroides Caleca, E. spuratus Caleca and E. undecim Caleca. A key to separate females is presented, and is based on the number of antennomeres and claval sensillar formula, mandibular spurs and teeth, palpal formula and clypeus, and some cephalic characters. Morphological adaptations of the head and mandibles are discussed in relation to host habitat and oviposition site. Information on host associations, habitat preference, seasonal and daily occurrence of some species a…
Lights and shadows of the Taenia asiatica life cycle and pathogenicity.
2013
Humans are definitive hosts of two well-known species of the Taenia genus, Taenia solium (the pig tapeworm) and Taenia saginata (the cattle tapeworm). In the 1990s, a third species, Taenia asiatica, was discovered, sharing features with the other two since the adult morphology is similar to that of T. saginata, but its life cycle is like that of T. solium. Human taeniasis usually is asymptomatic or displays mild symptoms, and only T. solium can cause other sometimes serious disorders when humans accidentally ingest the eggs and develop the larval stage in different organs (cysticercosis). In this review, we expose what we currently know (lights) and what we do not yet know (shadows) about t…
Multiscale modeling of polycrystalline materials: A boundary element approach to material degradation and fracture
2015
Abstract In this work, a two-scale approach to degradation and failure in polycrystalline materials is proposed. The formulation involves the engineering component level (macro-scale) and the material grain level (micro-scale). The macro-continuum is modeled using a three-dimensional boundary element formulation in which the presence of damage is formulated through an initial stress approach to account for the local softening in the neighborhood of points experiencing degradation at the micro-scale. The microscopic degradation is explicitly modeled by associating Representative Volume Elements (RVEs) to relevant points of the macro continuum, for representing the polycrystalline microstruct…
Formulations and valid inequalities for the capacitated dispersion problem
2023
This work focuses on the capacitated dispersion problem for which we study several mathematical formulations in different spaces using variables associated with nodes, edges, and costs. The relationships among the presented formulations are investigated by comparing the projections of the feasible sets of the LP relaxations onto the subspace of natural variables. These formulations are then strengthened with families of valid inequalities and variable-fixing procedures. The separation problems associated with the valid inequalities that are exponential in number are shown to be polynomially solvable by reducing them to longest path problems in acyclic graphs. The dual bounds obtained from s…
Il ruolo del familiae emptor nel testamentum per aes et libram
2016
L'intonaco Li Vigni nell'architettura del XX secolo a Palermo. Nuove conoscenze e applicazioni diagnostiche per la manutenzione
2013
Il saggio presenta lo studio degli intonaci formulati per imitare le pietre e i marmi naturali che si diffondono in Sicilia all’inizio del XX secolo ed evidenzia che le prime applicazioni e la diffusione delle nuove malte, anche nel resto dell’Italia, risentono delle sperimentazioni condotte in tutta l’Europa. Il contributo riassume i risultati di una rigorosa e capillare ricognizione tra i brevetti conservati presso l’Archivio Centrale dello Stato a Roma inerenti alle malte per il confezionamento dell’intonaco a “finta pietra”, ne analizza i contenuti in modo critico e pone in risalto i contatti culturali con le sperimentazioni dei materiali in atto nell’ambito dei grandi cantieri di resta…
Abitare nel reale. Dalla crisi della periferia alla tessitura di nuove relazioni contestuali
2019
I progetti redatti per “Palermo Sud-Est” sono il risultato di un Laboratorio di Laurea strutturatosi attraverso incontri, seminari, comunicazioni specialistiche, esposizioni critiche, che – in una strategia condivisa – ha visto ogni studente elaborare il proprio lavoro nel confronto con gli altri attori del Laboratorio stesso. La ricerca sui “progetti urbani” è stata impostata di modo che ogni laureando fosse messo a conoscenza dei progetti svolti nello stesso ambito territoriale dai colleghi che l’avevano preceduto, così da poter operare in continuità e contribuire a formulare un ragionamento unitario, nel quale ogni progetto costituisse continuazione, verifica o anche variante dei precede…
The Mathematicians’ Happy Hunting Ground: Einstein’s General Theory of Relativity
2004
There is hardly any doubt that for physics special relativity theory is of much greater consequence than the general theory. The reverse situation prevails with respect to mathematics: there special relativity theory had comparatively little, general relativity theory very considerable, influence, above all upon the development of a general scheme for differential geometry. —Hermann Weyl, “Relativity as a Stimulus to Mathematical Research,” pp. 536–537.
Seeing reality through Einstein's eyes: a teaching proposal for special relativity
2021
The teaching of Special Relativity is still a critical issue not only for students but also for teachers. In this paper, we describe the trial of a learning unit on the Special Relativity topic based on Minkowski's approach through spacetime diagrams, following the results in pedagogical researches in this field. The main innovation of our project consists of a mechanical instrument: it allows to physically and mechanically represent Lorentz’s transformations by hands, exploring the effects of a change of the reference frame. Teachers and students can deal “by eye” with unusual phenomena as the loss of simultaneity, time dilation, length contraction, relativistic addition of velocities and …