Dynamic correlation functions and Boltzmann Langevin approach for driven one dimensional lattice gas

We study the dynamics of the totally asymmetric exclusion process with open boundaries by phenomenological theories complemented by extensive Monte-Carlo simulations. Upon combining domain wall theory with a kinetic approach known as Boltzmann-Langevin theory we are able to give a complete qualitative picture of the dynamics in the low and high density regime and at the corresponding phase boundary. At the coexistence line between high and low density phases we observe a time scale separation between local density fluctuations and collective domain wall motion, which are well accounted for by the Boltzmann-Langevin and domain wall theory, respectively. We present Monte-Carlo data for the correlation functions and power spectra in the full parameter range of the model.Comment: 10 pages, 9 figure

Concettualizzazione e contestualizzazione dei beni culturali archeologici

This report describes the observations made while developing a new methodology for historic surveys used for the re-contextualisation of archaeological finds. This particular methodology avails itself of both traditional historic surveys as well as the representation of knowledge through ontology. The methodology described here was developed in reference to specific cases of re-contextualisation of archaeological artefacts from Pompeii which are now in the National Archaeological Museum in Naples

Bottleneck-induced transitions in a minimal model for intracellular transport

We consider the influence of disorder on the non-equilibrium steady state of a minimal model for intracellular transport. In this model particles move unidirectionally according to the \emph{totally asymmetric exclusion process} (TASEP) and are coupled to a bulk reservoir by \emph{Langmuir kinetics}. Our discussion focuses on localized point defects acting as a bottleneck for the particle transport. Combining analytic methods and numerical simulations, we identify a rich phase behavior as a function of the defect strength. Our analytical approach relies on an effective mean-field theory obtained by splitting the lattice into two subsystems, which are effectively connected exploiting the local current conservation. Introducing the key concept of a carrying capacity, the maximal current which can flow through the bulk of the system (including the defect), we discriminate between the cases where the defect is irrelevant and those where it acts as a bottleneck and induces various novel phases (called {\it bottleneck phases}). Contrary to the simple TASEP in the presence of inhomogeneities, many scenarios emerge and translate into rich underlying phase-diagrams, the topological properties of which are discussed.Comment: 14 pages, 15 figures, 1 tabl

Il progetto “ceraNEApolis”: un sistema informativo cartografico delle produzioni ceramiche a Neapolis (IV a.C.-VII d.C.)

In the last few decades, urban archaeology in Naples has contributed to outline the history of the city. The discovery of a great amount of pottery gave information about the daily life of ancient Naples. It was therefore decided to draw up a thematic archaeological map of the ceramics finds to reconstruct their production and distribution from the 4th century B.C. to the 7th century A.D. The project ceraNEApolis consists of a pottery map linked to a bibliographic database, which will be made available online: a working tool for experts, useful to outline the cultural city stratification and to understand the Neapolitan archaeological sites through the material. It is useful in defining the topography of production (workshop, raw materials, and resources), distribution (communication routes, harbour, market), uses and consumption patterns (house, habitat, sacred areas, burials) in the city, even if lacking monumental evidence. It contributes to the reconstruction and analysis of the cultural and urban landscape, taking into account the geomorphological elements and the data contexts even in diachronic and transversal multi-disciplinary perspective. The analysis of some significant cases shows its validity also for potential alternative fruition. The integration of virtual reality systems is a possible extension also for the knowledge, enhancement, communication and use of cultural heritage

Measurement of micro moulded parts by Computed Tomography and comparison to optical and tactile techniques

This paper focuses on dimensional verification of two micro-injection moulded components, selected from actual industrial productions, using CT metrological tools. In addition to CT scanning, also a tactile Coordinate Measuring Machine (CMM) with sub-micrometre uncertainty and an Optical Coordinate Measuring Machine (OCMM) allowing fast measurements suitable for in-line quality control were employed as validation instruments. The experimental work carried out and the analysis of the results provide valuable conclusions about the advantages and drawbacks of using CT metrology in comparison with CMM and OCMM when these techniques are employed for quality control of micro moulded parts

Sostenibilit\ue0 ambientale dei biocombustibili legnosi: importanza della filiera corta

Il legno \ue8 un materiale disponibile in abbondanza e, se la foresta \ue8 gestita in modo sostenibile, pu\uf2 rappresentare una fonte illimitata di materia prima per diversi settori industriali: dalla costruzione fino alla produzione di energia. Nel settore forestale, come in quello industriale, la domanda di una documentazione relativa alle sue prestazioni ambientali \ue8 in forte crescita. Per esempio, la certificazione ambientale di un prodotto da costruzione diventa necessaria in vista dell\u2019applicazione dei Criteri Ambientali Minimi (CAM) all\u2019edilizia a partire dall\u20191 gennaio 2021 mentre \ue8 gi\ue0 inclusa nella certificazione di qualit\ue0 dei biocombustibili solidi quali pellet (ENplus), bricchetti, cippato e legna da ardere (Biomassplus). Grazie alla competitivit\ue0 del costo della legna da ardere rispetto agli altri combustibili, l\u2019Italia storicamente ha una forte propensione all\u2019utilizzo di questo biocombustibile; tuttavia negli ultimi anni, si \ue8 sempre pi\uf9 sviluppato il mercato di importazione di legna da ardere, in particolar modo proveniente dall\u2019Est-Europa e dai Balcani. Il trasporto su strada della legna da ardere comporta degli input energetici nella filiera e conseguentemente delle emissioni di CO2. Questo studio confronta due diversi approcci di filiera: una filiera corta, in cui la legna da ardere \ue8 prodotta nella regione Veneto e in particolare in Cansiglio, e una filiera lunga, nella quale i tronchi per la produzione della legna da ardere vengono importati da paesi confinanti con l\u2019Italia. I tre obiettivi dello studio sono quelli di (i) valutare l\u2019impatto ambientale delle due filiere utilizzando 4 categorie di impatto, due globali (il potenziale di riscaldamento globale e il potenziale di riduzione dell\u2019ozono) e due locali (la formazione di smog fotochimico e la tossicit\ue0 umana); (ii) eseguire un\u2019analisi di sensitivit\ue0 per determinare la distanza critica del trasporto di legna da ardere e (iii) valutare la compensazione di CO2 in foresta. La metodologia adottata per la valutazione degli impatti ambientali delle due filiere \ue8 l\u2019analisi del ciclo di vita. Lo studio ha evidenziato che, nel caso della filiera corta, la fase critica del ciclo di vita \ue8 la combustione, mentre le operazioni forestali e il trasporto su strada hanno un contributo marginale sull\u2019impatto globale. Passando alla filiera lunga, escludendo le emissioni di CO2 di origine biogenica, il trasporto su strada diventa la fase critica

End-to-end Molecular Communication Channels in Cell Metabolism: an Information Theoretic Study

The opportunity to control and fine-tune the behavior of biological cells is a fascinating possibility for many diverse disciplines, ranging from medicine and ecology, to chemical industry and space exploration. While synthetic biology is providing novel tools to reprogram cell behavior from their genetic code, many challenges need to be solved before it can become a true engineering discipline, such as reliability, safety assurance, reproducibility and stability. This paper aims to understand the limits in the controllability of the behavior of a natural (non-engineered) biological cell. In particular, the focus is on cell metabolism, and its natural regulation mechanisms, and their ability to react and change according to the chemical characteristics of the external environment. To understand the aforementioned limits of this ability, molecular communication is used to abstract biological cells into a series of channels that propagate information on the chemical composition of the extracellular environment to the cell’s behavior in terms of uptake and consumption of chemical compounds, and growth rate. This provides an information-theoretic framework to analyze the upper bound limit to the capacity of these channels to propagate information, which is based on a well-known and computationally efficient metabolic simulation technique. A numerical study is performed on two human gut microbes, where the upper bound is estimated for different environmental compounds, showing there is a potential for future practical applications

Second-harmonic generation in silicon waveguides strained by silicon nitride

Silicon photonics meets the electronics requirement of increased speed and bandwidth with on-chip optical networks. All-optical data management requires nonlinear silicon photonics. In silicon only third-order optical nonlinearities are present owing to its crystalline inversion symmetry. Introducing a second-order nonlinearity into silicon photonics by proper material engineering would be highly desirable. It would enable devices for wideband wavelength conversion operating at relatively low optical powers. Here we show that a sizeable second-order nonlinearity at optical wavelengths is induced in a silicon waveguide by using a stressing silicon nitride overlayer. We carried out second-harmonic-generation experiments and first-principle calculations, which both yield large values of strain-induced bulk second-order nonlinear susceptibility, up to 40pm/V at 2.300 nm. We envisage that nonlinear strained silicon could provide a competing platform for a new class of integrated light sources spanning the near- to mid-infrared spectrum from 1.2 to 10 micron

Metabolic Synergy between Human Symbionts \u3ci\u3eBacteroides\u3c/i\u3e and \u3ci\u3eMethanobrevibacter\u3c/i\u3e

ABSTRACT Trophic interactions between microbes are postulated to determine whether a host microbiome is healthy or causes predisposition to disease. Two abundant taxa, the Gram-negative heterotrophic bacterium Bacteroides thetaiotaomicron and the methanogenic archaeon Methanobrevibacter smithii, are proposed to have a synergistic metabolic relationship. Both organisms play vital roles in human gut health; B. thetaiotaomicron assists the host by fermenting dietary polysaccharides, whereas M. smithii consumes end-stage fermentation products and is hypothesized to relieve feedback inhibition of upstream microbes such as B. thetaiotaomicron. To study their metabolic interactions, we defined and optimized a coculture system and used software testing techniques to analyze growth under a range of conditions representing the nutrient environment of the host. We verify that B. thetaiotaomicron fermentation products are sufficient for M. smithii growth and that accumulation of fermentation products alters secretion of metabolites by B. thetaiotaomicron to benefit M. smithii. Studies suggest that B. thetaiotaomicron metabolic efficiency is greater in the absence of fermentation products or in the presence of M. smithii. Under certain conditions, B. thetaiotaomicron and M. smithii form interspecies granules consistent with behavior observed for syntrophic partnerships between microbes in soil or sediment enrichments and anaerobic digesters. Furthermore, when vitamin B12, hematin, and hydrogen gas are abundant, coculture growth is greater than the sum of growth observed for monocultures, suggesting that both organisms benefit from a synergistic mutual metabolic relationship. IMPORTANCE The human gut functions through a complex system of interactions between the host human tissue and the microbes which inhabit it. These diverse interactions are difficult to model or examine under controlled laboratory conditions. We studied the interactions between two dominant human gut microbes, B. thetaiotaomicron and M. smithii, using a seven-component culturing approach that allows the systematic examination of the metabolic complexity of this binary microbial system. By combining high-throughput methods with machine learning techniques, we were able to investigate the interactions between two dominant genera of the gut microbiome in a wide variety of environmental conditions. Our approach can be broadly applied to studying microbial interactions and may be extended to evaluate and curate computational metabolic models. The software tools developed for this study are available as user-friendly tutorials in the Department of Energy KBase