Phylogenetics and Phylogeography in the Planktonic Diatom Genus <i>Chaetoceros</i>

The initial aims of this thesis were to assess the systematics of the planktonic diatom genus Chaetoceros and the phylogeographic patterns of selected species in this genus across spatial and temporal scales. As expected in every experiment, some initial ideas have been pursued as they were; others have taken a different route and led to different questions. Consequently, the systematics of Chaetoceros has become a multigene phylogeny and a revision of the classical taxonomic scheme for the family Chaetocerotaceae (Chapter II). Then, the phylogeographic approach, initially meant as a Sanger sequencing of a few genes from specimens collected around the world, turned into the analysis of the C. curvisetus cryptic species complex by using an approach which combines haplotype networks and metabarcoding data (Chapter IV). The mapping of this complex against a temporal metabarcoding dataset (MareChiara, Gulf of Naples, IT) has become a story of concerted evolution and has been extended to different Chaetoceros species and supported by a single strain 18S-V4 high throughput sequencing (Chapter V). Amid these experiments, the potential of metabarcoding data for biological recording was explored and tested in the whole genus Chaetoceros to assess diversity and distribution (Chapter III). Such data were integrated with classical ones from public repositories and literature and used to produce, among the other results, distribution maps of Chaetoceros species

Improved analysis of the bounds from the electroweak precision tests on the 4-site model

We present a new complete analysis of the electroweak precision observables within the recently proposed 4-site Higgsless model, which is based on the SU(2)_L x SU(2)_1 x SU(2)_2 x U(1)_Y gauge symmetry and predicts six extra gauge bosons, W_{1,2} and Z_{1,2}. Within the epsilon_i (i=1,2,3,b) parametrization, we compute for the first time the EWPT bounds via a complete numerical algorithm going beyond commonly used approximations. Both epsilon_{1,3} impose strong constraints. Hence, it is mandatory to consider them jointly when extracting EWPT bounds and to fully take in to account the correlations among the electroweak precison measurements. The phenomenological consequence is that the extra gauge bosons must be heavier than 250 GeV. Their couplings to SM fermions, even if bounded, might be of the same order of magnitude than the SM ones. In contrast to other Higgsless models, the 4-site model is not fermiophobic. The new gauge bosons could thus be discovered in the favoured Drell-Yan channel already during the present run of the LHC experiment.Comment: Latex file, 35 pages, 10 figures, corrected typos, published versio

Interference effects in heavy W'-boson searches at the LHC

Interference effects are widely neglected in searches for new physics. This is the case in recent publications on searches for W'-bosons using leptonic final states. We examine the effects of interference on distributions frequently used to determine mass limits for possible W'-bosons and show that there are important qualitative effects on the behaviour of the new physics signal. There are two main consequences. Firstly, exclusion limits where interferences effects have not been considered are likely to have been overestimated. Secondly, presenting experimental results as a function of a transverse mass cut rather than in terms of the contribution of new physics to the total cross-section would be more informative.Comment: 31 pages, 8 figures. Published versio

Communication Strategies for Strip-Like Topologies in Ad-Hoc Wireless Networks

Non

Critical comments on EEG sensor space dynamical connectivity analysis

Many different analysis techniques have been developed and applied to EEG recordings that allow one to investigate how different brain areas interact. One particular class of methods, based on the linear parametric representation of multiple interacting time series, is widely used to study causal connectivity in the brain. However, the results obtained by these methods should be interpreted with great care. The goal of this paper is to show, both theoretically and using simulations, that results obtained by applying causal connectivity measures on the sensor (scalp) time series do not allow interpretation in terms of interacting brain sources. This is because 1) the channel locations cannot be seen as an approximation of a source's anatomical location and 2) spurious connectivity can occur between sensors. Although many measures of causal connectivity derived from EEG sensor time series are affected by the latter, here we will focus on the well-known time domain index of Granger causality (GC) and on the frequency domain directed transfer function (DTF). Using the state-space framework and designing two simulation studies we show that mixing effects caused by volume conduction can lead to spurious connections, detected either by time domain GC or by DTF. Therefore, GC/DTF causal connectivity measures should be computed at the source level, or derived within analysis frameworks that model the effects of volume conduction. Since mixing effects can also occur in the source space, it is advised to combine source space analysis with connectivity measures that are robust to mixing

Cannabis; epidemiological, neurobiological and psychopathological issues: an update

This document is the Accepted Manuscript version of the following article: Maria Antonietta De Luca, Gaetano Di Chiara, Cristina Cadoni, Daniele Lecca, Laura Orsolini, Duccio Papanti, John Corkery, Fabrizio Schifano, 'Cannabis; Epidemiological, Neurobiological and Psychopathological Issues: An Update', CNS & Neurological Disorders - Drug Targets, Vol. 16, 2017. The published manuscript is available at EurekaSelect via https://doi.org/10.2174/1871527316666170413113246. Published by Bentham Science.Cannabis is the illicit drug with both the largest current levels of consumption and the highest reported lifetime prevalence levels in the world. Across different countries, the prevalence of cannabis use varies according to the individual income, with the highest use being reported in North America, Australia and Europe. Despite its ‘soft drug’ reputation, cannabis misuse may be associated with several acute and chronic adverse effects. The present article aims at reviewing several papers on epidemiological, neurobiological and psychopathological aspects of the use of cannabis. The PubMed database was here examined in order to collect and discuss a range of identified papers. Cannabis intake usually starts during late adolescence/early adulthood (15-24 years) and drastically decreases in adulthood with the acquisition of working, familiar and social responsibilities. Clinical evidence supports the current socio-epidemiological alarm concerning the increased consumption among youngsters and the risks related to the onset of psychotic disorders. The mechanism of action of cannabis presents some analogies with other abused drugs, e.g. opiates. Furthermore, it has been well demonstrated that cannabis intake in adolescence may facilitate the transition to the use and/or abuse of other psychotropic drugs, hence properly being considered a ‘gateway drug’. Some considerations on synthetic cannabimimetics are provided here as well. In conclusion, the highest prevalence of cannabis use and the social perception of a relatively low associated risk are in contrast with current knowledge based on biological and clinical evidence. Indeed, there are concerns relating to cannabis intake association with detrimental effects on both cognitive impairment and mental health.Peer reviewe