Permutazioni come prodotti di cicli

La tesi è relativa alle permutazioni come prodotti di cicli. Si introducono i primi concetti sulle permutazioni con i teoremi principali annessi, vengono definiti i Numeri di Stirling di primo e secondo tipo, i concetti delle funzioni generatrici e funzioni generatrici esponenziali; viene mostrata l'importante relazione tra permutazioni cicliche e alberi

Emerging role of gefitinib in the treatment of non-small-cell lung cancer (NSCLC)

Most patients with non-small-cell lung cancer (NSCLC) present with advanced disease and their long-term prognosis remains poor. Epidermal growth factor receptor (EGFR)-targeted therapies, such as gefitinib, have been subjected to comprehensive clinical development. Several phase II and III trials evaluated the clinical efficacy of gefitinib as monotherapy in pretreated patients with advanced NSCLC, as well as both monotherapy and combined with chemotherapy in chemotherapy-naive patients. A phase III trial (ISEL) in heavily pretreated advanced NSCLC patients demonstrated some improvement in survival with gefitinib compared with placebo; however, the difference was not statistically significant within the overall population. A large phase III trial in pretreated patients (INTEREST) demonstrated the non-inferiority of gefitinib in comparison with docetaxel for overall survival, together with an improved quality of life and tolerability profiles. In a large phase III trial (IPASS) in Asian chemotherapy-naive, never or former light-smoker patients with adenocarcinoma, gefitinib was more effective than carboplatin–paclitaxel in prolonging progression-free survival, particularly in patients harboring EGFR gene mutations. Gefitinib was a generally well tolerated treatment, with skin rash and diarrhea being the most common treatment adverse events. As a result, gefitinib is expected to have a large impact on the management of patients with advanced NSCLC, in particular in EGFR mutated patients

Gusci temporanei e ricomponibili: Utilizzo di un sistema multi-agente per la generazione di un sistema costruttivo a tasselli planari per superfici a doppia curvatura

Lo scopo della ricerca è quello di sviluppare un metodo di design che integri gli apporti delle diverse discipline di architettura, ingegneria e fabbricazione all’interno del progetto, utilizzando come caso di studio l’uso di una tettonica ad elementi planari in legno per la costruzione di superfici a guscio da utilizzare come padiglioni temporanei. La maniera in cui ci si propone di raggiungere tale scopo è tramite l’utilizzo di un agent based system che funge da mediatore tra i vari obbiettivi che si vogliono considerare, in questo caso tra parametri estetici, legati alla geometria scelta, e di fabbricazione. Si sceglie di applicare questo sistema allo studio di una struttura a guscio, che grazie alla sua naturale rigidezza integra forma e capacità strutturale, tramite una tassellazione planare della superficie stessa. Il sistema studiato si basa sull’algoritmo di circle relaxation, che viene integrato tramite dei comportamenti che tengano conto della curvatura della superficie in questione e altri comportamenti scelti appositamente per agevolare il processo di tassellazione tramite tangent plane intersection. La scelta di studiare elementi planari è finalizzata ad una maggiore facilità di fabbricazione ed assemblaggio prevedendo l’uso di macchine a controllo numerico per la fabbricazione e un assemblaggio interamente a secco e che non necessita di impalcature . Il risultato proposto è quello quindi di un padiglione costituito da elementi planari ricomponibili in legno, con particolare attenzione alla facilità e velocità di montaggio degli stessi, utile per possibili strutture temporanee e/o di emergenza

Selected new developments in computational chemistry.

Molecular dynamics is a general technique for simulating the time-dependent properties of molecules and their environments. Quantum mechanics, as applied to molecules or clusters of molecules, provides a prescription for predicting properties exactly (in principle). It is reasonable to expect that both will have a profound effect on our understanding of environmental chemistry in the future. In this review, we consider several recent advances and applications in computational chemistry

Costs and Benefits of Native Language Similarity for Non-native Word Learning

The present study examined the costs and benefits of native language similarity for non-native vocabulary learning. Because learning a second language (L2) is difficult, many learners start with easy words that look like their native language (L1) to jumpstart their vocabulary. However, this approach may not be the most effective strategy in the long-term, compared to introducing difficult L2 vocabulary early on. We examined how L1 orthographic typicality affects pattern learning of novel vocabulary by teaching English monolinguals either Englishlike or Non-Englishlike pseudowords that contained repeated orthographic patterns. We found that overall, the first words that individuals learned during initial acquisition influenced which words they acquired later. Specifically, learning a new word in one session made it easier to acquire an orthographically similar word in the next session. Similarity among non-native words interacted with native language similarity, so that words that looked more like English were easier to learn at first, but they were less effective at influencing later word learning. This demonstrates that although native language similarity has a beneficial effect early on, it may reduce learners' ability to benefit from non-native word patterns during continued acquisition. This surprising finding demonstrates that making learning easier may not be the most effective long-term strategy. Learning difficult vocabulary teaches the learner what makes non-native words unique, and this general wordform knowledge may be more valuable than the words themselves. We conclude that native language similarity modulates new vocabulary acquisition and that difficulties during learning are not always to be avoided, as additional effort early on can pay later dividends

Comment on "Critique of the foundations of time-dependent density functional theory" [Phys. Rev.A. 75, 022513 (2007)]

A recent paper (Phys. Rev A. 75, 022513 (2007), arXiv:cond-mat/0602020) challenges exact time-dependent density functional theory (TDDFT) on several grounds. We explain why these criticisms are either irrelevant or incorrect, and that TDDFT is both formally exact and predictive.Comment: 4 pages; This is a Comment on the paper cited above, also at arXiv:cond-mat/060202

Analysis of Floquet formulation of time-dependent density-functional theory

Floquet formulation of time-dependent density-functional theory is revisited in light of its recent criticism [Maitra and Burke, Chem. Phys. Lett. 359 (2002), 237]. It is shown that Floquet theory is well founded and its criticism has overlooked important points of both the Runge-Gross formalism and Floquet formulation itself. We substantiate our analysis by examples similar to that considered by Maitra and Burke.Comment: 17 pages, 2 figures. accepted for publication in "Chemical Physics Letters

Frank Discussion of the Status of Ground-state Orbital-free DFT

F.E. Harris has been a significant partner in our work on orbital-free density functional approximations for use in ab initio molecular dynamics. Here we mention briefly the essential progress on single-point functionals since our original paper (2006). Then we focus on the advantages and limitations of generalized gradient approximation (GGA) non-interacting kinetic-energy functionals. We reconsider the constraints provided by near-origin conditions in atomic-like systems and their relationship to regularized versus physical external potentials. Then we seek the best empirical GGA for the non-interacting KE for a modest-sized set of molecules with a well-defined near-origin behavior of their densities. The search is motivated by a desire for insight into GGA limitations and for a target for constraint-based development

An Atomic Model for the Pleated β-Sheet Structure of Aβ Amyloid Protofilaments

Synchrotron x-ray studies on amyloid fibrils have suggested that the stacked pleated beta-sheets are twisted so that a repeating unit of 24 beta-strands forms a helical turn around the fibril axis (. J. Mol. Biol. 273:729-739). Based on this morphological study, we have constructed an atomic model for the twisted pleated beta-sheet of human Abeta amyloid protofilament. In the model, 48 monomers of Abeta 12-42 stack (four per layer) to form a helical turn of beta-sheet. Each monomer is in an antiparallel beta-sheet conformation with a turn located at residues 25-28. Residues 17-21 and 31-36 form a hydrophobic core along the fibril axis. The hydrophobic core should play a critical role in initializing Abeta aggregation and in stabilizing the aggregates. The model was tested using molecular dynamics simulations in explicit aqueous solution, with the particle mesh Ewald (PME) method employed to accommodate long-range electrostatic forces. Based on the molecular dynamics simulations, we hypothesize that an isolated protofilament, if it exists, may not be twisted, as it appears to be when in the fibril environment. The twisted nature of the protofilaments in amyloid fibrils is likely the result of stabilizing packing interactions of the protofilaments. The model also provides a binding mode for Congo red on Abeta amyloid fibrils. The model may be useful for the design of Abeta aggregation inhibitors

Density-functional embedding using a plane-wave basis

The constrained electron density method of embedding a Kohn-Sham system in a substrate system (first described by P. Cortona, Phys. Rev. B {\bf 44}, 8454 (1991) and T.A. Wesolowski and A. Warshel, J. Phys. Chem {\bf 97}, 8050 (1993)) is applied with a plane-wave basis and both local and non-local pseudopotentials. This method divides the electron density of the system into substrate and embedded electron densities, the sum of which is the electron density of the system of interest. Coupling between the substrate and embedded systems is achieved via approximate kinetic energy functionals. Bulk aluminium is examined as a test case for which there is a strong interaction between the substrate and embedded systems. A number of approximations to the kinetic-energy functional, both semi-local and non-local, are investigated. It is found that Kohn-Sham results can be well reproduced using a non-local kinetic energy functional, with the total energy accurate to better than 0.1 eV per atom and good agreement between the electron densities.Comment: 11 pages, 4 figure