Finite-Time Consensus with Disturbance Rejection by Discontinuous Local Interactions in Directed Graphs

In this technical note we propose a decentralized discontinuous interaction rule which allows to achieve consensus in a network of agents modeled by continuous-time first-order integrator dynamics affected by bounded disturbances. The topology of the network is described by a directed graph. The proposed discontinuous interaction rule is capable of rejecting the effects of the disturbances and achieving consensus after a finite transient time. An upper bound to the convergence time is explicitly derived in the technical note. Simulation results, referring to a network of coupled Kuramoto-like oscillators, are illustrated to corroborate the theoretical analysis

Analisi della attivita muscolare anticipatoria nel movimento di raggiungimento dell'arto superiore: effetto della diversa attivazione iniziale del tronco e della velocità di spostamento dell'arto

Studio osservazionale su 18 soggetti adulti sani. Analisi EMG dei muscoli LT,LD e EO rispetto al Deltoide durante un raggiungimento da posizione seduta. Sono state utilizzate 3 modalita  sperimentali: due con variazione della posizione seduta ed una con velocita  elevata. I risultati hanno dimostrato come l'attivazione posturale preventiva riduca il lavoro muscolare necessario per la stabilizzazione mentre la maggiore velocita  produca una maggiore partecipazione dei muscoli posturali.ope

Spontaneous CP violation in the Next-to-Minimal Supersymmetric Standard Model

In this thesis we will investigate CP violation within the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The study of the violation of the CP symmetry is relevant for several reasons. The origin of CP symmetry violation observed experimentally in the kaon system and nowhere else, is still uncertain and under active investigation. Also, and perhaps more intriguing, CP violation is a necessary ingredient of explanations of baryogenesis: supersymmetric theories allow for several sources of CP violation, whether explicit or not, therefore guaranteeing the necessary amount of CP violation. In fact, there are potentially so many CP violating phases, that it is an issue whether supersymmetry is compatible with the tight experimental constraints on the electron and neutron electric dipole moments. In particular we will concentrate on the study of Spontaneous CP Violation (SCPV), where the vacuum is CP non conserving. In the Standard Model, although the Electroweak symmetry is spontaneously broken, SCPV cannot occur, as at least two Higgs doublets are needed. Also, within the simplest extension of the Standard Model, the Minimal Supersymmetric Standard Model, SCPV, although possible in principle, is ruled out experimentally. Here we will show a detailed analysis of possible SCPV under general assumptions within the NMSSM. The implications of this are also addressed both for experiments at high energy colliders and also at low energy for the neutron and electron electric dipole moments when the CP violating phases are large. We have considered these phases as arbitrary parameters, and have studied the consequences as a function of the amount of CP violation present. In chapter 1 and 2 we briefly review the MSSM and the NMSSM. In chapter 3 we review the literature on SCPV, in both models, as a comparison. We also discuss the assumptions and formalism which will be used extensively in the following analysis. In chapter 4 we discuss weak SCPV 1 and its possible experimental consequences. The study of this scenario will effectively constitute the main aim of this work. In chapter 5 we present a thorough numerical analysis of SCPV both weak and not, over a vast area of the parameter space. The chapter also includes a discussion of the Higgs sector when CP is not violated, and when it is violated explicitly. In chapter 6 we address the issue of whether SCPV within the NMSSM is experimentally testable with emphasis on the weak SCPV case. In chapter 7 we then discuss the constraints coming from the neutron and electron electric dipole moments, which are relevant when SCPV is not weak. We then summarise our overall conclusions

J/psi production in p-A collisions at 158 and 400 GeV: recent results from the NA60 experiment

The NA60 experiment has studied muon pair production in p-A and In-In collisions at the CERN SPS. We present new results on nuclear effects on J/psi production in p-A at 158 GeV, the same energy used for collecting A-A data at the SPS. We then compare nuclear effects with previous results from fixed target experiments, and with the results obtained from a p-A data sample taken by NA60 at 400 GeV. Based on the 158 GeV results, we calculate the expected J/psi suppression in In-In and Pb-Pb collisions due to cold nuclear matter effects, and we extract a new estimate for the anomalous suppression at SPS energies. Finally, we show preliminary results on J/psi polarization in p-A collisions.Comment: 4 pages, 4 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse

Structured population balances to support microalgae-based processes: Review of the state-of-art and perspectives analysis

Design and optimization of microalgae processes have traditionally relied on the application of unsegregated mathematical models, thus neglecting the impact of cell-to-cell heterogeneity. However, there is experimental evidence that the latter one, including but not limited to variation in mass/size, internal composition and cell cycle phase, can play a crucial role in both cultivation and downstream processes. Population balance equations (PBEs) represent a powerful approach to develop mathematical models describing the effect of cell-to-cell heterogeneity. In this work, the potential of PBEs for the analysis and design of microalgae processes are discussed. A detailed review of PBE applications to microalgae cultivation, harvesting and disruption is reported. The review is largely focused on the application of the univariate size/mass structured PBE, where the size/mass is the only internal variable used to identify the cell state. Nonetheless, the need, addressed by few studies, for additional or alternative internal variables to identify the cell cycle phase and/or provide information about the internal composition is discussed. Through the review, the limitations of previous studies are described, and areas are identified where the development of more reliable PBE models, driven by the increasing availability of single-cell experimental data, could support the understanding and purposeful exploitation of the mechanisms determining cell-to-cell heterogeneity

Computational analysis of dynamic light exposure of unicellular algal cells in a flat-panel photobioreactor to support light-induced CO2 bioprocess development

Cyanobacterial cell factories trace a vibrant pathway to climate change neutrality and sustainable development owing to their ability to turn carbon dioxide-rich waste into a broad portfolio of renewable compounds, which are deemed valuable in green chemistry cross-sectorial applications. Cell factory design requires to define the optimal operational and cultivation conditions. The paramount parameter in biomass cultivation in photobioreactors is the light intensity since it impacts cellular physiology and productivity. Our modeling framework provides a basis for the predictive control of light-limited, light-saturated, and light-inhibited growth of the Synechocystis sp. PCC 6803 model organism in a flat-panel photobioreactor. The model here presented couples computational fluid dynamics, light transmission, kinetic modeling, and the reconstruction of single cell trajectories in differently irradiated areas of the photobioreactor to relate key physiological parameters to the multi-faceted processes occurring in the cultivation environment. Furthermore, our analysis highlights the need for properly constraining the model with decisive qualitative and quantitative data related to light calibration and light measurements both at the inlet and outlet of the photobioreactor in order to boost the accuracy and extrapolation capabilities of the model

Momenti di occupazione e ristrutturazione del nuraghe Orgono di Ghilarza (OR)

Riassunto: Recenti lavori di consolidamento del nuraghe Orgono di Ghilarza (OR) sono stati affiancati dallo scavo delle due camere della singolare struttura. I risultati più importanti si sono avuti nell’indagine dei due focolari sovrapposti della camera superiore, pertinenti a due distinti momenti di frequentazione: età del ferro ed età romana (fine repubblica-inizio impero). Il primo era sigillato dalla sistemazione pavimentale di epoca storica, il secondo dal sopravvenuto crollo della volta. Entrambi propongono lo studio di alcuni manufatti ceramici di scarsa qualità, solo in parte ispirati ai repertori tipologici dei rispettivi periodi e pertanto difficilmente collocabili tra le produzioni ceramiche conosciute, che sembrano attestare la lunga sopravvivenza di tecniche di lavorazione domestica.Abstract: Besides recent consolidation works of nuraghe Orgono (Ghilarza - OR), both rooms of the uncommon structure have been excavated. The most important results come from the research of the two superimposed hearths of the upper room, which belong to two distinct occupation moments: Iron Age and Roman Age (Late Republic - Early Empire). The former was covered by the floor of historical period, the latter by the collapse of the vault. Both hearths propose the study of some pottery products of low quality, which are only partly inspired to the typologies of their respective periods and therefore can hardly be placed among the known pottery productions, which suggest a long survival of home working techniques

Diet in the Sardinian Bronze Age: models, collagen isotopic data, issues and perspectives

Traditional reconstructions depict Sardinian Bronze Age economy as a mixed one characterized by a remarkable importance of pastoralism, opposed to a more ‘agricultural’ Neolithic. The first few isotopic data, though not unambiguously, seem to indicate quite the opposite compared with earlier times, reflecting possibly a higher dependence on vegetal foods, with possible marginal contributions of aquatic foods and/or C4 plants at one coastal site. However, the importance of ecosystem-wide shifts in interpreting collagen data for comparative purposes is underlined, with specific examples from Sardinia, and so is the rarity of collections including faunal and botanical specimens alongside humans, which would help establish a local isotopic baseline. Efforts to discriminate animal vs. vegetal contributions in Bronze Age diets that are fully based on C3 ecosystems, therefore, remain tentative. Isotopic research in progress on Sardinian diet and climate from the Copper Age up to the Nuragic Late Bronze (2800-1100 BC) is expected to provide a better grasp on temporal and geographic variation.Les reconstitutions alimentaires traditionnelles dépeignent l’économie de l’âge du Bronze en Sardaigne comme une économie mixte caractérisée par une grande importance de l’élevage des moutons, juxtaposée à une période néolithique plus agricole. Les premières données isotopiques, bien que peu nombreuses encore, semblent, d’une façon ambigüe, plutôt indiquer le contraire lorsqu’on les compare aux données des périodes précédentes. Elles montrent une plus grande dépendance des aliments végétaux avec peut-être la contribution marginale d’aliments aquatiques et/ou des plantes issues du milieu côtier. Afin de palier le manque d’études sur les restes fauniques et botaniques et dans le but de réaliser des comparaisons à l’échelle de la Sardaigne, une analyse détaillée des données isotopiques des collagènes a été réalisée pour cerner l’importance de modifications isotopiques de l’écosystème tout entier. Une recherche en cours sur la diète et sur le climat dans la Sardaigne à partir du Néolithique jusqu’à l’âge du Fer (4700-500 avant J.C.) devrait permettre une meilleure interprétation de la variabilité isotopique d’un point de vue chronologique et géographique