Electronic zero-point oscillations in the strong-interaction limit of density functional theory

The exchange-correlation energy in Kohn-Sham density functional theory can be expressed exactly in terms of the change in the expectation of the electron-electron repulsion operator when, in the many-electron hamiltonian, this same operator is multiplied by a real parameter $\lambda$ varying between 0 (Kohn-Sham system) and 1 (physical system). In this process, usually called adiabatic connection, the one-electron density is kept fixed by a suitable local one-body potential. The strong-interaction limit of density functional theory, defined as the limit $\lambda\to\infty$, turns out to be, like the opposite non-interacting Kohn-Sham limit ($\lambda\to 0$) mathematically simpler than the physical ($\lambda=1$) case, and can be used to build an approximate interpolation formula between $\lambda\to 0$ and $\lambda\to\infty$ for the exchange-correlation energy. Here we extend the exact treatment of the $\lambda\to\infty$ limit [Phys. Rev. A {\bf 75}, 042511 (2007)] to the next leading term, describing zero-point oscillations of strictly correlated electrons, with numerical examples for small spherical atoms. We also propose an improved approximate functional for the zero-point term and a revised interpolation formula for the exchange-correlation energy satisfying more exact constraints.Comment: 11 pages, submitted to J. Chem. Theory Compu

Webcrow: A web-based system for crossword solving

Language games represent one of the most fascinating challenges of research in artificial intelligence. In this paper we give an overview of WebCrow, a system that tackles crosswords using the Web as a knowledge base. This appears to be a novel approach with respect to the available literature. It is also the first solver for non-English crosswords and it has been designed to be potentially multilingual. Although WebCrow has been implemented only in a preliminary version, it already displays very interesting results reaching the performance of a human beginner: crosswords that are “easy ” for expert humans are solved, within competition time limits, with 80 % of correct words and over 90 % of correct letters

Correlation between CT and pathological findings in lung adenocarcinoma

The aim of this retrospective study was to determine CT appearance of 38 lung nodules that underwent CT-guided biopsies for cytological and/or histological evaluation. At biopsy all these lesions resulted lung adenocarcinoma. Unenhanced and contrast-enhanced CT examinations and CT-guided biopsies of all lesions were performed by using a 64-channel CT and a high definition 64-channels CT at Radiology Department of University of Pisa between June and December 2013. Using radiological criteria, the new 2011 adenocarcinoma classification was applied to characterize these 38 lesions in the adenocarcinoma spectrum. CT characteristics of the nodules (nodule presentation, size, location and number) were registered by using the PACS system. According to the new classification the results were: one preinvasive lesions (AIS), two minimally invasive lesions (MIA) and 35 invasive lesions. A better application of the new lung adenocarcinoma classification both by the pathologists and the radiologists will allow an improved definition of the lesions in the adenocarcinoma spectrum, from premalignant to frankly invasive lesions which necessitate different ways of management.

Analisi farmacogenetica dell’enzima TPMT in pazienti in trattamento con azatioprina

Introduzione. La comparsa di eventi avversi e il fallimento terapeutico sono problemi che si manifestano spesso in corso di trattamento con azatioprina (AZA) in pazienti affetti da malattie infiammatorie croniche reumatologiche e gastroenterologiche. AZA subisce un metabolismo inattivante da parte dell’enzima tiopurina-metiltransferasi (TPMT), la cui attività è principalmente influenzata da quattro polimorfismi genici a singolo nucleotide. Obiettivo. Lo studio oggetto della presente tesi è stato condotto con l’obiettivo di valutare la distribuzione del genotipo (studio dei polimorfismi genici) e del fenotipo (analisi dell'attività enzimatica) dell'enzima TPMT e la capacità di questi determinanti di predire tossicità ed efficacia di AZA in una coorte di pazienti gastroenterologici e reumatologici affetti da patologie infiammatorie croniche. Metodi. I genotipi TPMT *2,*3A,*3B,*3C sono stati analizzati con metodica PCR (restriction fragment length polymorphism o metodiche allele-specifiche), mentre l’attività enzimatica intraeritrocitaria di TPMT è stata valutata con saggi di High Performance Liquid Chromatography (conversione di 6-tioguanina in 6-metil-tioguanina, 6MTG). I dati clinici dei pazienti sono stati raccolti dalle cartelle cliniche delle Unità Operative di Reumatologia, Pediatria e Gastroenterologia Universitaria dell’Azienda Ospedaliero-Universitaria Pisana. Risultati. Per la valutazione della prevalenza delle mutazioni, sono stati analizzati 223 pazienti che hanno mostrato i genotipi seguenti: omozigosi *1/*1 o wild type (WT) (n=208); omozigosi *3C/*3C (n=1), eterozigosi *1/*3A (n=11); eterozigosi *1/*3C (n=2) e eterozigosi *3A/*3C (n=1). Per la valutazione della capacità predittiva dell’assetto genetico di TPMT su efficacia e tollerabilità di AZA, sono stati valutati 104 pazienti affetti da malattia di Crohn (n=15), rettocolite ulcerosa (n=12), connettiviti sistemiche (n=35), vasculiti (n=28) e altre malattie autoimmuni (n=14). In 40 pazienti (38,5%), entro una mediana di 7 mesi (intervallo: 0,5-80), sono stati osservati uno o più degli eventi avversi seguenti: leucopenia (10,6%), infezioni gravi (5,8%), tossicità epatica (13,5%), pancreatite (2,9%), sintomi gastrointestinali (8,7%) o sistemici (7,7%). Polimorfismi TMPT sono stati evidenziati in 4 pazienti: 3 eterozigoti TPMT*3A (2,9%) e 1 omozigote *3C/*3C (0,9%). Tra questi, 3 pazienti hanno sviluppato tossicità. AZA è risultata efficace in 89 pazienti (n=87 WT, n=2 *1/*3A) e inefficace in 4 (n=2 WT, n=1 *1/*3A, n=1 *3C/*3C). Il genotipo WT è risultato predittivo di successo terapeutico (RR 1,74; IC 0,65-4,65; p<0,04). L’attività TPMT mediana, analizzata in un sottogruppo di 27 pazienti (n=26 WT, n=1 *1/*3A), è risultata 54,2 nmol 6MTG/gHb/h (intervallo: 32,4-106,8). In accordo con un cut-off validato, è stata osservata una ridotta attività enzimatica in 3 pazienti WT e 1 eterozigote. I valori di attività TPMT nei rimanenti pazienti WT (n=23) sono risultati entro l’intervallo di normalità. Tra questi pazienti, 9/23 hanno sviluppato eventi avversi e 18/23 hanno manifestato un buon controllo di malattia. Conclusioni. La presenza di polimorfismi TPMT può predire la comparsa di tossicità correlata al trattamento con AZA. La presenza di un genotipo WT appare un buon predittore di efficacia terapeutica, ma non esclude la possibilità di sviluppare eventi avversi. La valutazione del fenotipo TPMT suggerisce che un controllo favorevole della malattia possa essere ottenuto nei pazienti con attività enzimatica normale. La valutazione combinata di genotipo e fenotipo TPMT può rappresentare un utile strumento farmacologico per la gestione clinica dei pazienti in trattamento con AZA

Persistent Homology analysis of Phase Transitions

Persistent homology analysis, a recently developed computational method in algebraic topology, is applied to the study of the phase transitions undergone by the so-called XY-mean field model and by the phi^4 lattice model, respectively. For both models the relationship between phase transitions and the topological properties of certain submanifolds of configuration space are exactly known. It turns out that these a-priori known facts are clearly retrieved by persistent homology analysis of dynamically sampled submanifolds of configuration space.Comment: 10 pages; 10 figure

Velocity-dependent quantum phase slips in 1D atomic superfluids

Quantum phase slips are the primary excitations in one-dimensional superfluids and superconductors at low temperatures but their existence in ultracold quantum gases has not been demonstrated yet. We now study experimentally the nucleation rate of phase slips in one-dimensional superfluids realized with ultracold quantum gases, owing along a periodic potential. We observe a crossover between a regime of temperature-dependent dissipation at small velocity and interaction and a second regime of velocity-dependent dissipation at larger velocity and interaction. This behavior is consistent with the predicted crossover from thermally-assisted quantum phase slips to purely quantum phase slips.Comment: 7 pages, 6 figure

Towards A New Decision Support System for Design, Management and Operation of Wastewater Treatment Plants for the Reduction of Greenhouse Gases Emission

The increasing attention paid to the environment has led to a reduction in the emissions from wastewater treatment plants (WWTPs). Moreover, the increasing interest in the greenhouse gas (GHG) emissions from WWTPs suggests that we reconsider the traditional tools used for designing and managing WWTPs. Indeed, nitrous oxide, carbon dioxide and methane can be emitted from wastewater treatment, significantly contributing to the greenhouse gas (GHG) footprint. The reduction of energy consumption as well as GHG emission are of particular concern for large WWTPs which treat the majority of wastewater in terms of both volume and pollution load. Nowadays, there is an increasing need to develop new tools that include additional performance indicators related to GHG emissions and energy consumption as well as traditional effluent quality parameters. Energy consumption, in fact, can be considered as an indirect source of GHGs. This paper presents the development of an ongoing research project aiming at setting-up an innovative mathematical model platform for the design and management of WWTPs. The final goal of the project by means of this platform is to minimize the environmental impact of WWTPs through their optimization in terms of energy consumptions and emissions, which can be regarded as discharged pollutants, sludge and GHGs

Observation of a disordered bosonic insulator from weak to strong interactions

We employ ultracold atoms with controllable disorder and interaction to study the paradigmatic problem of disordered bosons in the full disorder-interaction plane. Combining measurements of coherence, transport and excitation spectra, we get evidence of an insulating regime extending from weak to strong interaction and surrounding a superfluid-like regime, in general agreement with the theory. For strong interaction, we reveal the presence of a strongly-correlated Bose glass coexisting with a Mott insulator