43,927 research outputs found
Polynomial filtering for linear discrete time non-Gaussian systems
No full textIn this work we propose a new filtering approach for linear discrete time non-Gaussian systems that generalizes a previous result concerning quadratic filtering [A. De Santis, A. Germani, and M. Raimondi, IEEE Trans. Automat. Control, 40 (1995) pp. 1274-1278]. A recursive nu th-order polynomial estimate of finite memory Delta is achieved by defining a suitable extended state which allows one to solve the filtering problem via the classical Kalman linear scheme. The resulting estimate will be the mean square optimal one among those estimators that take into account nu-polynomials of the last Delta observations. Numerical simulations show the effectiveness of the proposed method
Testing van der Waals interactions with quantum dynamics: Repulsive anisotropy and well depth in the LiH plus He system
No full textRecent calculations on the rigid rotor surface for the LiH-He interaction [B. K. Taylor and R. J. Hinde, J. Chem. Phys. 111, 973 (1999)] surmised that the well depth and anisotropy of the new surface differ substantially from the latest valence bond calculations for the same system [F. A. Gianturco, S. Kumar, S. K. Pathak, M. Raimondi, M. Sironi, J. Gerratt, and D. L. Cooper, Chem. Phys. 215, 227 (1997)]. We examine in detail the performance of both these potential energy surfaces once employed to generate quantum observables which can be compared with experiments. Our computations clearly show that the two surfaces exhibit small differences in their short-range repulsive anisotropy and larger differences in well depths. The latter however cannot be assessed as yet from existing experiments. The different behavior of their wells in supporting van der Waals bound states is also examined and spectroscopic experiments are suggested for detecting possible transitions between such states. (C) 2000 American Institute of Physics. [S0021- 9606(00)00341-X]
Marx: la produzione del soggetto
No full textQuesto testo è il primo esito di un seminario tenutosi presso l'Università di Padova al quale hanno partecipato studenti, dottorandi, ricercatori e docenti di varie università. Il volume analizza il significato storico, teorico e politico che la nozione di soggetto assume in alcune opere di Marx dai primi agli ultimi scritti
Introduzione
No full textIl termine "soggetto" e i suoi derivati non compaiono spesso nei testi marxiani. Il lavoro concettuale svolto da Marx attorno al problema del soggetto scientifico e del soggetto politico esercita tuttavia, a dispetto delle più immediate apparenze, un ruolo cruciale nelle sue pagine. Nel presente volume si è cercato di fornire alcune indicazioni sulle specificità e sull'operatività politica del concetto in questione
A sliding mass wave energy converter
No full textThis paper presents a wave energy converter which is based on a sliding mass coupled to a linear generator. In order to maximize energy extraction, the stochastic features of the energy source has been included in the mathematical model of the system in order to satisfactorily tackle the problem. The results of several simulations are presented
Application of valence-bond techniques to the study of weakly bound complexes. The potential energy surface of the Ne-CH4 system
No full textWe present a comprehensive survey of the Molecular Orbital-Valence Bond ( MO-VB) method, a theoretical scheme developed within the framework of the Valence Bond theory to deal with weakly bound intermolecular complexes. According to the MO-VB, the wavefunction of the system is expressed as a truncated non-orthogonal Configuration Interaction expansion, which is size extensive and a priori free of basis set superposition error. We report on the recent developments of the method, which extend the range of application of the MO-VB to intermolecular complexes with a quite large number of correlated electrons, showing that VB-based methods are nowadays a valid alternative to Molecular Orbital approaches also in this field. The MO-VB has been applied to study extensively the Ne-CH4 complex, and compared with the more standard MP4 and CCSD( T) results. We determined two analytical Potential Energy Surfaces ( PES) for this system, computed at MO-VB and MP4 level, which represent the first ones coming entirely from ab initio computations. The features of our potentials are discussed, and compared to the single analytical potential which includes the anisotropy available in the literature, determined about twenty years ago by Udo Buck and co-workers using a semiempirical approach [ U. Buck, A. Kolhase, D. Secrest, T. Phillips, G. Scoles and F. Grein, Mol. Phys., 1985, 55, 1233]. The differences among the three PES are quite relevant, and are due to play a relevant role in the theoretical simulations of the dynamical properties of the Ne-CH
Emofiltrazione artero venosa continua (CAVH) nello scompenso cardiaco come mezzo per evitare la ventilazione artificiale
No full textThree-dimensional reactive surfaces for the LiH2+ system: An analysis of accurate ab initio results
No full textCalculations for the reactive potential energy surfaces, which are relevant for examining the low-energy channels connected with the LiH2 three ato
m ionic system. are carried out using a multireference valence bond (MRVB) approach. More than 11.000 points have been computed over the grid of the three
relevant coordinates (two bond distances and the enclosed angle) and the lowest three electronic states have been followed over the spatial configuration o
f the above coordinates. Several aspects of the reactive behavior could be gleaned from an analysis of the computed surfaces and various features of the re
active outcomes are extracted from that analysis
Deciphering the deformation modes associated with function retention and specialization in members of the Ras superfamily
No full textThe evolutionary and physical deformability patterns of members of the Ras GTPase superfamily were investigated by Principal Component and Elastic Network-Normal Mode analyses. The study helped to decipher the dynamics information encrypted into the conserved core and to separate the trans-family intrinsic flexibility associated with a common function from the protein motions related to functional specialization of selected families or family members. The conserved core is dynamically divided into two lobes. The deformation modes, which allow the Ras GTPases to accomplish their switching function, are conserved along evolution and are localized in lobe 1 portions close to the nucleotide. These modes lead to functional specialization when associated with evolution-driven deformations of protein portions essentially located in lobe 2, distal from the nucleotide, and involved in peculiar interactions with membrane, guanine nucleotide exchange factors, or effectors. Overall, a complete picture of the functional and evolutionary dynamics of the Ras superfamily emerges
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