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Fame for Sale: Efficient Detection of Fake Twitter Followers
Get PDFFake followers?are those Twitter accounts specifically created to inflate the number of followers of a target account. Fake followers are dangerous for the social platform and beyond, since they may alter concepts like popularity and influence in the Twittersphere - hence impacting on economy, politics, and society. In this paper, we contribute along different dimensions. First, we review some of the most relevant existing features and rules (proposed by Academia and Media) for anomalous Twitter accounts detection. Second, we create a baseline dataset of verified human and fake follower accounts. Such baseline dataset is publicly available to the scientific community. Then, we exploit the baseline dataset to train a set of machine-learning classifiers built over the reviewed rules and features. Our results show that most of the rules proposed by Media provide unsatisfactory performance in revealing fake followers, while features proposed in the past by Academia for spam detection provide good results. Building on the most promising features, we revise the classifiers both in terms of reduction of overfitting and cost for gathering the data needed to compute the features. The final result is a novel?Class A?classifier, general enough to thwart overfitting, lightweight thanks to the usage of the less costly features, and still able to correctly classify more than 95% of the accounts of the original training set. We ultimately perform an information fusion-based sensitivity analysis, to assess the global sensitivity of each of the features employed by the classifier. The findings reported in this paper, other than being supported by a thorough experimental methodology and interesting on their own, also pave the way for further investigation on the novel issue of fake Twitter followers
Indagini sui sedimenti del Lago Maggiore. Campionamento, preparazione dei campioni e datazione
Get PDFNot availableIndagini su DDT e sostanze pericolose nell\u27ecosistema del Lago Maggiore. Programma 2013-2015. Rapporto annuale 2014 - Indagini sui sedimenti del Lago Maggiore. Campionamento, preparazione dei campioni e datazion
Evoluzione stagionale e a lungo termine delle caratteristiche chimiche del Lago Maggiore e bilancio dei nutrienti a Lago (Azoto e Fosforo)
Get PDFNot availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2014. Evoluzione stagionale e a lungo termine delle caratteristiche chimiche del Lago Maggiore e bilancio dei nutrienti a Lago (Azoto e Fosforo). Chimica di base e contenuto ionico delle acque lacustri. Nutrienti a lago (composti dell\u27Azoto e del Fosforo e silicati). Ossigeno disciolto. Metalli in tracce. Apporti chimici dai tributari e dell\u27emissario. Concentrazioni medie areali. Carichi chimici e bilanci di Azoto e Fosforo
Ricerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 2014
Get PDFNot availableRicerche sull\u27evoluzione del Lago Maggiore. Aspetti limnologici. Programma triennale 2013-2015. Campagna 201
The trophic reliance of methane in the benthic food web: natural versus anthropogenic drivers
Get PDFIt is now widely recognized that biogenic methane can contribute up to 80% of the chironomid biomass in case of hypoxic tropholytic zone. However, several studies have revealed that hypoxic deep conditions can appear more or less abruptly through time, suggesting that the biogenic methane contribution is not the \u27reference\u27 functioning in most lakes. This study aims at identifying the causes of the trophic reliance of methane (\u27TRM\u27) activation, and to understand the environmental conditions that enable the activation of the TRM. Three different lakes (productivity, altitude, water depth, etc.) were investigated using paleolimnological approach. The methodological strategy is built in three steps: (i) the reconstruction of the temporal evolution of methanotroph availability (ancient DNA of methanotroph) and the chironomid paleo-diet (carbon stable isotopes), (ii) the comparison of these dynamics with the histories of climate variability and anthropogenic pressures (pollen analysis) (iii) and the assessment of the environmental conditions (trophic state, oxygen conditions and organic matter accumulation) that allowed this activation. Results reveal very contrasting evolutions suggesting (i) that this pathway is highly driven by human and climate pressures and (ii) that lakes seem to have a various \u27sensibility\u27 facing the activation and the modulation of the TRM
Fish in lake ecological assessment in Europe: Quo Vadis?
Get PDFIt is well established that fish are sensitive indicators of environmental degradation and offer the major advantage of integrating the direct and indirect effects of stress over large scales of space and time. Nevertheless, the use of fish communities as indicators of environmental quality is highly challenging, therefore fish community has been one of the most neglected aspect of lake ecological monitoring. This paper gives an overview on fish-based assessment methods in Europe. By now, 15 Member States have finalised fish-based lake assessment systems, five of these assessment systems have been recently intercalibrated in the Alpine and Northern region, while Intercalibration is still ongoing in the Central-Baltic region. In contrary, several countries of the Mediterranean region have currently renounced the use of fish in lake assessment (mainly due to a low species richness, dominance of invasive taxa, and high costs of sampling), this opinion being strongly debated within region. This paper seeks to answer questions: How lake fish ecological assessment systems are built and used across Europe? Which pressures are assessed and are the pressure-response relationships tested? What are the main lessons and challenges of the lake fish methods` development and harmonization process
Problems related to measurements oflow values of total alkalinity and pH in dilute samples
Get PDFThe resuts of the working ring test are analysed to help labs to improve their result
Horizontal gene transfer in bdelloid rotifers is ancient, ongoing and more frequent in species from desiccating habitats
Get PDFBackground Although prevalent in prokaryotes, horizontal gene transfer (HGT) is rarer in multicellular eukaryotes. Bdelloid rotifers are microscopic animals that contain a higher proportion of horizontally transferred, non-metazoan genes in their genomes than typical of animals. It has been hypothesized that bdelloids incorporate foreign DNA when they repair their chromosomes following double-strand breaks caused by desiccation. HGT might thereby contribute to species divergence and adaptation, as in prokaryotes. If so, we expect that species should differ in their complement of foreign genes, rather than sharing the same set of foreign genes inherited from a common ancestor. Furthermore, there should be more foreign genes in species that desiccate more frequently. We tested these hypotheses by surveying HGT in four congeneric species of bdelloids from different habitats: two from permanent aquatic habitats and two from temporary aquatic habitats that desiccate regularly. Results Transcriptomes of all four species contain many genes with a closer match to non-metazoan genes than to metazoan genes. Whole genome sequencing of one species confirmed the presence of these foreign genes in the genome. Nearly half of foreign genes are shared between all four species and an outgroup from another family, but many hundreds are unique to particular species, which indicates that HGT is ongoing. Using a dated phylogeny, we estimate an average of 12.8 gains versus 2.0 losses of foreign genes per million years. Consistent with the desiccation hypothesis, the level of HGT is higher in the species that experience regular desiccation events than those that do not. However, HGT still contributed hundreds of foreign genes to the species from permanently aquatic habitats. Foreign genes were mainly enzymes with various annotated functions that include catabolism of complex polysaccharides and stress responses. We found evidence of differential loss of ancestral foreign genes previously associated with desiccation protection in the two non-desiccating species. Conclusions Nearly half of foreign genes were acquired before the divergence of bdelloid families over 60 Mya. Nonetheless, HGT is ongoing in bdelloids and has contributed to putative functional differences among species. Variation among our study species is consistent with the hypothesis that desiccating habitats promote HGT
Ruolo del sapere tecnico e del vissuto di catastrofe naturale nella rappresentazione sociale del rischio: primi risultati di una ricerca svolta nella provincia di Ferrara
No full textIl rischio pu? essere considerato un prodotto culturale socialmente costruito attraverso discorsi, policies, media, appartenenza culturale e processi storici e sociali (Beck, 1996). ? la comunit? che individua i fenomeni degni di attenzione e fa s? che alcuni rischi vengano messi in evidenza e riconosciuti come tali mentre altri, ugualmente pericolosi, vengano ignorati. Sono proprio queste valutazioni, che non si basano mai completamente su dati oggettivi, che orientano la pianificazione e realizzazione degli interventi da parte delle istituzioni, come pure l\u27adozione di comportamenti da parte dei cittadini. Lo studio presentato in questo contributo ha indagato l\u27influenza del tipo di sapere posseduto (tecnico vs senso comune) e dell\u27esperienza personale di catastrofi ambientali sulla rappresentazione sociale del rischio. Lo studio ha coinvolto 190 persone residenti in provincia di Ferrara. Dal punto di vista metodologico ? stato utilizzato il metodo delle libere associazioni, facendo riferimento alla teoria del nucleo centrale delle rappresentazioni sociali (Abric, 2011). Le associazioni libere sono state raccolte tramite un questionario costruito ad hoc. I dati sono stati analizzati tramite il software EVOC. I risultati mostrano che la rappresentazione sociale del rischio naturale si struttura intorno al concetto di pericolo, con particolare riferimento al terremoto, nonch? ad aspetti emotivi e comportamentali. Tra i primi l\u27emozione prevalente ? la paura; tra i secondi si fa riferimento soprattutto alla prevenzione. Il possesso di una conoscenza tecnica e l\u27aver vissuto un terremoto incidono sulla struttura della rappresentazione del rischio. I risultati confermano in parte quanto emerso in altre ricerche, mostrando anche delle specificit? legate al contesto in cui ? stato condotto lo studio. In particolare ? emerso che eventi traumatici collettivi, come il terremoto, entrano rapidamente e stabilmente a far parte del vissuto di una comunit?, connotandone la rappresentazione del rischio. Tali risultati saranno utilizzati nell\u27ambito di un percorso di formazione - ricerca partecipato
The role of intrinsic motivations in the development of tool use: a study in infant robots
Get PDFThe aim of this work is to investigate, through "infant robots", the key role of intrinsic motivations (IMs) in the development of the capacity to solve the rake tool-use task