Characteristic exponents of complex networks

We present a novel way to characterize the structure of complex networks by studying the statistical properties of the trajectories of random walks over them. We consider time series corresponding to different properties of the nodes visited by the walkers. We show that the analysis of the fluctuations of these time series allows to define a set of characteristic exponents which capture the local and global organization of a network. This approach provides a way of solving two classical problems in network science, namely the systematic classification of networks, and the identification of the salient properties of growing networks. The results contribute to the construction of a unifying framework for the investigation of the structure and dynamics of complex systems.Comment: 6 pages, 5 figures, 1 tabl

Toward Reverse Engineering of VBA Based Excel Spreadsheet Applications

Modern spreadsheet systems can be used to implement complex spreadsheet applications including data sheets, customized user forms and executable procedures written in a scripting language. These applications are often developed by practitioners that do not follow any software engineering practice and do not produce any design documentation. Thus, spreadsheet applications may be very difficult to be maintained or restructured. In this position paper we present in a nutshell two reverse engineering techniques and a tool that we are currently realizing for the abstraction of conceptual data models and business logic models.Comment: In Proceedings of the 2nd Workshop on Software Engineering Methods in Spreadsheets (http://spreadsheetlab.org/sems15/

Erosion Rate of the Aliano Biancana Badlands Based on a 3D Multi-Temporal High-Resolution Survey and Implications for Wind-Driven Rain

Biancana badlands are peculiar landforms in the Basilicata region of Italy resulting from the local combination of geological, geomorphological, and climatic settings. The evolution of badlands mainly depends on slope erosion, which is controlled by the angle, exposure, and vegetation of the slope and its interactions with insolation, rain, and wind. Multi-temporal, detailed, high-resolution surveys have led researchers to assess changes in slopes to investigate the spatial distributions of erosion and deposition and the influence of wind-driven rain (WDR). A comparison between two terrestrial laser scanner (TLS) point clouds surveyed during 2006 and 2016 fieldwork showed that the study area suffers from intense erosion that is not spatially uniform on all sides of biancane. By combining slope and exposure data and the cloud of difference (CoD), derived from a 3D model, we showed that all the steepest southern sides of biancane suffered the most intense erosion. Because splash and sheet erosion triggers sediment displacement, the analysis was also focused on the intensity and direction of WDR. We performed a real field experiment analysing erosion rates over 10 years in relation to daily and hourly wind data (direction and speed), and we found that frequent winds of moderate force, combined with moderate to heavy rainfall, contributed to the observed increase in soil erosion when combined with the insolation effect. Our results show how all the considered factors interact in a complex pattern to control the spatial distribution of erosion

Emittance Characterization of Ion Beams Provided by Laser Plasma

Laser ion sources offer the possibility to obtain ion beams useful for particle accelerators. Nanosecond pulsed lasers at intensities of the order of 108 W/cm2, interacting with solid matter in a vacuum, produce plasma of high temperature and high density. To increase the ion energy, an external post-acceleration system can be employed by means of high voltage power supplies of some tens of kV. In this work, we characterize the ion beams provided by an LIS source and post-accelerated. We calculated the produced charge and the emittance. Applying 60 kV of accelerating voltage and laser irradiance of 0.1 GW/cm2 on the Cu target, we obtain 5.5 mA of output current and normalized beam emittance of 0.2 mm mrad. The brightness of the beams was 137 mA (mm mrad)−2

On the compliance of thermal performance requirements for highly insulated building units

The target of the nearly zero-energy building (nZEB), stated by the European Union, represents one of the most strenuous challenges to reduce energy consumptions and greenhouse gas emissions in the building sector. In Italy, the nZEB concept refers to a set of energy performance requirements, fixed at national level and establishing a maximum allowable mean thermal transmittance value of the building envelope, as a function of the heating degree-days and of the shape factor. The building envelope is becoming more and more thermally insulated; this determines the reduction of the energy need for heating, but on the other hand it can cause the indoor overheating and the resulting increase of the energy need for cooling. In the design of highly energy efficient buildings, the different energy needs should be kept in balance as to increase the overall energy performance. The article aims to investigate the conditions and extent for which the envelope insulation is beneficial for containing overall energy needs. A sensitivity analysis that involves different insulation levels of the building envelope is performed on some apartments of a typical residential building, located in three different Italian climatic zones. The energy performance calculations are carried out by means of a detailed dynamic simulation tool (EnergyPlus). The results point out that, whereas the effect of increasing the thermal insulation causes a stable reduction of the energy need for heating, the energy need for cooling is very sensitive to the apartment storey; specifically, it increases in ground-floor apartments, and decreases for topfloor building units. Its reduction becomes progressively more consistent at the decrease of the heating degree-days. Considering the annual imbalances between the energy needs for cooling and heating due to the hyper-insulated envelope, reference values of thermal transmittance can be derived as to maximise the overall energy performance of the building

Characterization and Phytotoxicity Assessment of Essential Oils from Plant Byproducts

The present work describes the chemical characterization and the phytotoxicity assessment of essential oils (EOs) obtained from spent materials or pruning waste of four plant species: Zingiber officinale Roscoe used in the juicing industry, Pistacia vera L. var. Bronte used in the food industry, discarded material of industrial hemp (Cannabis sativa L. var. Futura 75), and pruning waste from Cupressus sempervirens L. The phytochemical profile of the EOs was evaluated by gas chromatographic flame ionization detection (GC-FID) and GC-MS analyses, which highlighted the presence of several compounds with a wide range of biological activities. Among them, application possibilities in agriculture were evaluated by studying the phytotoxic activity in vitro against germination and initial radical growth of several seeds such as Raphanus sativus L., Lepidium sativum L., Lactuca sativa L., Solanum lycopersicum L., Lolium multiflorum Lam., and Portulaca oleracea L

Adult human biliary tree stem cells differentiate to β-pancreatic islet cells by treatment with a recombinant human Pdx1 peptide

Generation of β-pancreatic cells represents a major goal in research. The aim of this study was to explore a protein-based strategy to induce differentiation of human biliary tree stem cells (hBTSCs) towards β-pancreatic cells. A plasmid containing the sequence of the human pancreatic and duodenal homeobox 1 (PDX1) has been expressed in E. coli. Epithelial-Cell-Adhesion-Molecule positive hBTSCs or mature human hepatocyte cell line, HepG2, were grown in medium to which Pdx1 peptide was added. Differentiation toward pancreatic islet cells were evaluated by the expression of the β-cell transcription factors, Pdx1 and musculoapo-neurotic fibrosarcoma oncogene homolog A, and of the pancreatic hormones, insulin, glucagon, and somatostatin, investigated by real time polymerase chain reaction, western blot, light microscopy and immunofluorescence. C-peptide secretion in response to high glucose was also measured. Results indicated how purified Pdx1 protein corresponding to the primary structure of the human Pdx1 by mass spectroscopy was efficiently produced in bacteria, and transduced into hBTSCs. Pdx1 exposure triggered the expression of both intermediate and mature stage β-cell differentiation markers only in hBTSCs but not in HepG2 cell line. Furthermore, hBTSCs exposed to Pdx1 showed up-regulation of insulin, glucagon and somatostatin genes and formation of 3-dimensional islet-like structures intensely positive for insulin and glucagon. Finally, Pdx1-induced islet-like structures exhibited glucose-regulated C-peptide secretion. In conclusion, the human Pdx1 is highly effective in triggering hBTSC differentiation toward functional β-pancreatic cells

A Presentation of Ionic Liquids as Lubricants: Some Critical Comments

Ionic liquids (ILs) are liquid materials at room temperature with an ionic intrinsic nature. The electrostatic interactions therefore play a pivotal role in dictating their inner structure, which is then expected to be far from the traditional pattern of classical simple liquids. Therefore, the strength of such interactions and their long-range effects are responsible for the ionic liquid high viscosity, a fact that itself suggests their possible use as lubricants. More interestingly, the possibility to establish a wide scenario of possible interactions with solid surfaces constitutes a specific added value in this use. In this framework, the ionic liquid complex molecular structure and the huge variety of possible interactions cause a complex aggregation pattern which can depend on the presence of the solid surface itself. Although there is plenty of literature focusing on the lubricant properties of ionic liquids and their applications, the aim of this contribution is, instead, to furnish to the reader a panoramic view of this exciting problematic, commenting on interesting and speculative aspects which are sometimes neglected in standard works and trying to furnish an enriched vision of the topic. The present work constitutes an easy-to-read critical point of view which tries to interact with the imagination of readers, hopefully leading to the discovery of novel aspects and interconnections and ultimately stimulating new ideas and research