KK-monopoles and G-structures in M-theory/type IIA reductions

We argue that M-theory/massive IIA backgrounds including KK-monopoles are suitably described in the language of G-structures and their intrinsic torsion. To this end, we study classes of minimal supergravity models that admit an interpretation as twisted reductions in which the twist parameters are not restricted to satisfy the Jacobi constraints $\omega\, \omega=0$ required by an ordinary Scherk-Schwarz reduction. We first derive the correspondence between four-dimensional data and torsion classes of the internal space and, then, check the one-to-one correspondence between higher-dimensional and four-dimensional equations of motion. Remarkably, the whole construction holds regardless of the Jacobi constraints, thus shedding light upon the string/M-theory interpretation of (smeared) KK-monopoles.Comment: 38 pages, 1 figure, 1 table; v2: refs added, published versio

Lobotomy of Flux Compactifications

We provide the dictionary between four-dimensional gauged supergravity and type II compactifications on $\mathbb{T}^6$ with metric and gauge fluxes in the absence of supersymmetry breaking sources, such as branes and orientifold planes. Secondly, we prove that there is a unique isotropic compactification allowing for critical points. It corresponds to a type IIA background given by a product of two 3-tori with SO(3) twists and results in a unique theory (gauging) with a non-semisimple gauge algebra. Besides the known four AdS solutions surviving the orientifold projection to $\mathcal{N}=4$ induced by O6-planes, this theory contains a novel AdS solution that requires non-trivial orientifold-odd fluxes, hence being a genuine critical point of the $\mathcal{N}=8$ theory.Comment: 44 pages (33 pages + appendices), 13 tables, 3 figure

A unifying framework for kk-statistics, polykays and their multivariate generalizations

Through the classical umbral calculus, we provide a unifying syntax for single and multivariate $k$-statistics, polykays and multivariate polykays. From a combinatorial point of view, we revisit the theory as exposed by Stuart and Ord, taking into account the Doubilet approach to symmetric functions. Moreover, by using exponential polynomials rather than set partitions, we provide a new formula for $k$-statistics that results in a very fast algorithm to generate such estimators.Comment: Published in at http://dx.doi.org/10.3150/07-BEJ6163 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Executive functions in the elderly with Mild Cognitive Impairment: a systematic review on motor and cognitive inhibition, conflict control and cognitive flexibility

Background: Mild Cognitive Impairment (MCI) is a syndrome characterised by mild cognitive decline, on one or more domains, but which does not compromise daily functions. Several studies have investigated the relationship between MCI and deficit in executive functions (EFs) but, unlike robust evidence in the mnestic domain, the nature of executive deficits in the MCI population remains uncertain. Objectives: This systematic review aims to evaluate EFs in patients with MCI, considering inhibition (motor and cognitive), conflict control and cognitive flexibility. Method: The databases used for the search were PUBMED, PsycINFO, PsycARTICLES and MEDLINE. Eligibility criteria: use of specific paradigms for EFs assessment ("Wisconsin Card Sorting Test", "Stroop Task", "Go/No-Go Task", "Flanker Task"); age over 65, studies published in English. Exclusion criteria: presence of dementia; psychiatric disorders; stroke; cranial trauma; inclusion of participants with MCI in groups with healthy elderly or those with dementia. Results: Fifty-five studies were selected, namely: Stroop Task (N=30), WCST (N=14), Go/No-Go (N=9), Flanker Task (N=2). Results have shown in people with MCI deficits in all the EFs considered. Conclusions: The results of this review support the applicability of the four experimental tasks examined for the study of EFs in people with MCI. These paradigms are useful in research, diagnosis and therapeutic purposes, allowing obtaining an articulated EFs profile that can compromise the daily life in elderly. These EFs are not generally evaluated by standard assessment of MCI, but their evaluation can lead to a better knowledge of MCI and help in the diagnosis and treatment

Sharp estimates for the anisotropic torsional rigidity and the principal frequency

In this paper we generalize some classical estimates involving the torsional rigidity and the principal frequency of a convex domain to a class of functionals related to some anisotropic non linear operators

QFIELD, PYARCHINIT AND BRADYPUS, INTERCHANGE OF PROTOCOLS AND WORKFLOWS FOR ACADEMIC RESEARCH

In the past, documenting archaeological research was based mainly on subjective experience due to the lack of digital platforms that would standardise documenting a context. Although it is in the last two decades that practise has been digitally standardardised. Some user-friendly systems help collect and organise data. Sometimes, the seem non-interoperable. Then it is to study a uniwue method capable of making different software comminicate with each other. The aim of this study is the integration of state-of-the-art software to aid in developing a criterion for the creation of an archaeological data interchange protocol. FLOSS was chosen as it offers the highest level of interoperability. One premise, it is assumed that you already have pyArchInit 2.6.2 on your computer, a server with Bradypus 4.0 installend and a postgreSQL database

Band-wise Hyperspectral Image Pansharpening using CNN Model Propagation

Hyperspectral pansharpening is receiving a growing interest since the last few years as testified by a large number of research papers and challenges. It consists in a pixel-level fusion between a lower-resolution hyperspectral datacube and a higher-resolution single-band image, the panchromatic image, with the goal of providing a hyperspectral datacube at panchromatic resolution. Thanks to their powerful representational capabilities, deep learning models have succeeded to provide unprecedented results on many general purpose image processing tasks. However, when moving to domain specific problems, as in this case, the advantages with respect to traditional model-based approaches are much lesser clear-cut due to several contextual reasons. Scarcity of training data, lack of ground-truth, data shape variability, are some such factors that limit the generalization capacity of the state-of-the-art deep learning networks for hyperspectral pansharpening. To cope with these limitations, in this work we propose a new deep learning method which inherits a simple single-band unsupervised pansharpening model nested in a sequential band-wise adaptive scheme, where each band is pansharpened refining the model tuned on the preceding one. By doing so, a simple model is propagated along the wavelength dimension, adaptively and flexibly, with no need to have a fixed number of spectral bands, and, with no need to dispose of large, expensive and labeled training datasets. The proposed method achieves very good results on our datasets, outperforming both traditional and deep learning reference methods. The implementation of the proposed method can be found on https://github.com/giu-guarino/R-PN

Vehicular Traffic on Networks: Comparison among Solutions Modeling Vertex Flow

2015 - 2016Nowadays, the analysis of issues associated with road traffic within urban and suburban areas has taken a leading role in trying to implement efficient plans of transport regulations by taking advantage of the available infrastructure. In fact, the occurrence frequency of slowdowns phenomena and strong congestions has greatly multiplied and caused a series of inconveniences and poor services for citizens such as the increased risk of accidents and air and noise pollution. In order to solve the problem of urban mobility, it is possible to act with a rational management of infrastructure and a road artery-planning program using simulators able to identify critical points in the design phase and evaluate the correctness of the proposed interventions. For this reason, it is important to use mathematical models to predict the evolution of the traffic starting from the knowledge of quantities such as cars’ densities at a given time instant. These models are classified into microscopic and macroscopic ones. The former analyze the behavior of each single vehicle, while the latter consider situations that arise from the interaction of many particles derived based on concepts of the fluid dynamics. The aim of the present research work is to review macroscopic fluid dynamic models dealing with traffic flow on road networks and to propose new solutions for the dynamics at intersections based on the integration of optimization criteria about the vehicular flow and rules for the distribution of traffic. In detail, the Thesis analyzes, describes and highlights the following topics and results: physical variables that regulate road traffic and the relation that links them with each other, and some fluid dynamic macroscopic models for traffic on a single road (i.e. LWR, Payne Whitham, Aw-Rascle, Zhang, Third order and Multilane models); vehicular traffic network based on the fluid dynamic model LWR and conservation laws, and characterized by some aspects to be solved like initial conditions on not infinite roads and dynamics at intersections. About the former aspect, the corresponding boundary value problems are presented and solved, while about the latter aspect the solution to Riemann Solver is given by considering also additional rules for traffic distribution that are well defined in new appropriate models simulating the presence of traffic lights at intersections with variable or fixed cycles of red-green; numerical schemes used for the discretization of the conservation law and the solution of the dynamic at intersections. In detail, Godunov scheme, used for the determination of density values for road sections in different time instants starting from the initial density value of each road on the analyzed road network, is considered; numerical results about an experimentation of some of the new models defined that are implemented within a road traffic simulator prototype by reproducing the behavior of vehicular densities on a road network with appropriate dynamics at intersections. These results are then compared in order to prove the correctness of each model, evaluate the performances and analyze some specific situations for optimization of car traffic. Considerations and results obtained in this research work by simulation of traffic flows may be useful as support for authorities responsible for urban road network in order to make an appropriate urban planning by evaluating the needs of the country. In fact, it could be possible to avoid traffic congestion at certain areas or time slots, bring down the rate of air pollution or noise and minimize risks due to overcrowding of vehicles on roads. [edited by author]Oggigiorno, l'analisi delle problematiche legate al traffico stradale nelle aree urbane e suburbane ha avuto un ruolo di primo piano nel tentativo di attuare piani efficienti di regolamentazione dei trasporti sfruttando le infrastrutture disponibili. Infatti, la frequenza dei fenomeni di rallentamento e di congestione si è moltiplicata e ha causato una serie di inconvenienti e scarsi servizi per i cittadini, come l'aumento del rischio di incidenti e di inquinamento atmosferico ed acustico. Al fine di risolvere il problema della mobilità urbana, è possibile agire con una gestione razionale delle infrastrutture e un programma di pianificazione dell'arteria stradale utilizzando simulatori in grado di individuare punti critici nella fase di progettazione e valutare la correttezza degli interventi proposti. Per questo motivo, è importante utilizzare modelli matematici per prevedere l'evoluzione del traffico a partire dalla conoscenza di quantità come la densità di un veicolo in un dato istante di tempo. Tali modelli sono classificati in microscopici e macroscopici. I primi analizzano il comportamento di ogni singolo veicolo, mentre i secondi considerano situazioni che derivano dall'interazione di molte particelle derivate in base ai concetti della fluido-dinamica. Lo scopo del presente lavoro di ricerca è quello di analizzare i modelli fluido-dinamici macroscopici che trattano il flusso di traffico sulle reti stradali e di proporre nuove soluzioni per le dinamiche agli incroci basate sull'integrazione di criteri di ottimizzazione del flusso veicolare con regole di distribuzione del traffico. In dettaglio, la tesi analizza, descrive ed evidenzia i seguenti argomenti e risultati: le variabili fisiche che regolano il traffico stradale e la relazione che le lega tra loro, ed alcuni modelli fluido-dinamici macroscopici per il traffico su singola strada (ovvero i modelli LWR, Payne-Whitham, Aw-Rascle, Zhang, Third order e Multilane); la rete di traffico veicolare basata sul modello fluido-dinamico LWR e sulle leggi di conservazione e caratterizzata da alcuni aspetti da risolvere come le condizioni iniziali sulle strade non infinite e le dinamiche agli incroci. Per quanto riguarda il primo aspetto, vengono presentati e risolti i problemi di “condizione al bordo” corrispondenti, mentre per quanto riguarda il secondo aspetto viene presentata la soluzione al problema di Riemann considerando anche regole aggiuntive e ben definite per la distribuzione del traffico in nuovi modelli che simulano la presenza di semafori agli incroci con cicli variabili o fissi di rosso-verde; gli schemi numerici per la discretizzazione della legge di conservazione e la soluzione alle dinamiche agli incroci. In dettaglio, viene considerate lo schema di Godunov, usato per determinare i valori di densità dei segmenti di strada in diversi istanti di tempo a partire dal valore di densità iniziale di ogni strada nella rete stradale analizzata; i risultati numerici della sperimentazione di alcuni dei nuovi modelli definiti, che sono implementati all’interno di un prototipo di simulatore del traffico stradale riproducendo il comportamento delle densità dei veicoli nella rete stradale con appropriate dinamiche agli incroci. Tali risultati sono successivamente confrontati per provare la correttezza di ogni modello, valutare le prestazioni e analizzare alcune specifiche situazioni per ottimizzare il traffico stradale. I risultati e le considerazioni emerse dal presente lavoro di ricerca simulando flussi veicolari possono essere di aiuto alle autorità responsabili della rete stradale urbana per progettare un efficiente piano di viabilità valutando le reali necessità della città. Infatti, si potrebbero evitare congestioni di traffico in certe aree della città o in specifici intervalli temporali, diminuire sostanzialmente il tasso di inquinamento atmosferico o acustico e minimizzarne i rischi dovuti al sovraffollamento di veicoli lungo le strade. [a cura dell'autore]XV n.s

On a reverse Kohler-Jobin inequality

We consider the shape optimization problems for the quantities $\lambda(\Omega)T^q(\Omega)$, where $\Omega$ varies among open sets of $\mathbb{R}^d$ with a prescribed Lebesgue measure. While the characterization of the infimum is completely clear, the same does not happen for the maximization in the case $q>1$. We prove that for $q$ large enough a maximizing domain exists among quasi-open sets and that the ball is optimal among {\it nearly spherical domains}