Euclid and the scientific thought in the third century B.C.

The criticism on the texts of Euclid, even assuming different positions, starts generally from the previous assumption that the author of the Elements is  totally inside the Platonic-Aristotelian tradition. The thesis affirmed in this paper is that many of the gaps and contradictions found by the criticism have their root in this assumption. The authors assert that Euclid was a scientist that belonged in a full way to the new cultural climate of the Hellenistic Kingdoms, and particularly of the Alexandria’s Museum. In this climate, characterized by lively philosophical disputes, the scientists, and in particular Euclid, tend to obtain coherent and stable results, voluntarily omitting to give their opinion on the real being of the scientificobject and on the truth of the principles

Temperature dependence of the ohmic conductivity and activation energy of Pb1+y(Zr0.3Ti0.7)O3 thin films

The ohmic conductivity of the sol-gel derived Pb1+y(Zr0.3Ti0.7)O3 thin films (with the excess lead y=0.0 to 0.4) are investigated using low frequency small signal alternate current (AC) and direct current (DC) methods. Its temperature dependence shows two activation energies of 0.26 and 0.12 eV depending on temperature range and excess Pb levels. The former is associated with Pb3+ acceptor centers, while the latter could be due to a different defect level yet to be identified.Comment: 13 pages, 3 figures, PostScript. Submitted to Applied Physics Letter

Archimede aristotelico o platonico: "tertium non datur"?

The aim of the present paper is to continue a critical study on Hellenistic Sciences. Such a study began with some previous papers on Euclid, where some remarkable aspects of the Alexandrinian mathematician emerged; in particular, we focused on some characters, innovative with respect to the previous Greek philosophical tradition and undervalued until now by historiography and critical literature. Here, the figure of Archimedes is analysed in the light of previous results and consequent criteria; he is freed from a long tradition, started with Plutarch, that sees the Sicilian scientist inside a Platonistic (in some sense) paradigm or, inversely, in an Aristotelian one. The re-reading of his works in the light of the new hypotheses, as expressed by other authors and scholars, allows us to delineate a more pragmatic and modern figure of scientist. In particular, some metaphysical problems as those concerning the Truth and Prime Causes, that were central in the Platonic-Aristotelian tradition, are in such a way avoided or suspended, in favour of more exact and appropriate modelling tools that make the phenomenical world more predictable and controllable also by technologies

Exploring low-degree nodes first accelerates network exploration

We consider information diffusion on Web-like networks and how random walks can simulate it. A well-studied problem in this domain is Partial Cover Time, i.e., the calculation of the expected number of steps a random walker needs to visit a given fraction of the nodes of the network. We notice that some of the fastest solutions in fact require that nodes have perfect knowledge of the degree distribution of their neighbors, which in many practical cases is not obtainable, e.g., for privacy reasons. We thus introduce a version of the Cover problem that considers such limitations: Partial Cover Time with Budget. The budget is a limit on the number of neighbors that can be inspected for their degree; we have adapted optimal random walks strategies from the literature to operate under such budget. Our solution is called Min-degree (MD) and, essentially, it biases random walkers towards visiting peripheral areas of the network first. Extensive benchmarking on six real datasets proves that the---perhaps counter-intuitive strategy---MD strategy is in fact highly competitive wrt. state-of-the-art algorithms for cover

Exploring plastic biofilm formation and Escherichia coli colonisation in marine environments

Microorganisms, including potential pathogens, can colonise plastic surfaces in aquatic environments. This study investigates the colonisation of plastic pellets by Escherichia coli (E. coli) as a proxy for faecal pathogens in aquatic environments. Plastic pellets from a polluted beach were placed in seawater aquaria spiked with E. coli. Diverse bacteria, primarily from the Proteobacteria phylum, rapidly colonised the pellets within 24 h, with notable species known for plastic or hydrocarbon degradation. Over 26 days, biofilms formed on the plastic surfaces, reaching bacterial populations of up to 6.8·105 gene copies (gc) of the 16S rRNA mm-2. E. coli, was detected in the pellets for up to 7 days using culture methods, exhibiting varying attachment densities regardless of source or environmental factors. The study highlights plastic biofilms as reservoirs for E. coli, contributing to the survival and persistence of faecal bacteria in aquatic systems. These findings deepen our understanding of the risks associated with plastic pollution in marine settings, offering insights into the behaviour of faecal indicators and their implications for water quality assessments, while providing valuable information on potential pathogen dissemination within plastic-associated microbial communities

Sentiment analysis in geo social streams by using machine learning technique

Dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science in Geospatial TechnologiesMassive amounts of sentiment rich data are generated on social media in the form of Tweets, status updates, blog post, reviews, etc. Different people and organizations are using these user generated content for decision making. Symbolic techniques or Knowledge base approaches and Machine learning techniques are two main techniques used for analysis sentiments from text. The rapid increase in the volume of sentiment rich data on the web has resulted in an increased interaction among researchers regarding sentiment analysis and opinion (Kaushik & Mishra, 2014). However, limited research has been conducted considering location as another dimension along with the sentiment rich data. In this work, we analyze the sentiments of Geotweets, tweets containing latitude and longitude coordinates, and visualize the results in the form of a map in real time. We collect tweets from Twitter using its Streaming API, filtered by English language and location (bounding box). For those tweets which don’t have geographic coordinates, we geocode them using geocoder from GeoPy. Textblob, an open source library in python was used to calculate the sentiments of Geotweets. Map visualization was implemented using Leaflet. Plugins for clusters, heat maps and real-time have been used in this visualization. The visualization gives an insight of location sentiments