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The stability region of the delay in Pareto opportunistic networks
Get PDFThe intermeeting time, i.e., the time between two consecutive contacts between a pair of nodes, plays a fundamental role in the delay of messages in opportunistic networks. A desirable property of message delay is that its expectation is finite, so that the performance of the system can be predicted. Unfortunately, when intermeeting times feature a Pareto distribution, this property does not always hold. In this paper, assuming heterogeneous mobility and Pareto intermeeting times, we provide a detailed analysis of the conditions for the expectation of message delay to be finite (i.e., to converge) when social-oblivious or social-aware forwarding schemes are used. More specifically, we consider different classes of social-oblivious and social-aware schemes, based on the number of hops allowed and the number of copies generated. Our main finding is that, in terms of convergence, allowing more than two hops may provide advantages only in the social-aware case. At the same time, we show that using a multi-copy scheme can in general improve the convergence of the expected delay. We also compare social-oblivious and social-aware strategies from the convergence standpoint and we prove that, depending on the mobility scenario considered, social-aware schemes may achieve convergence while social-oblivious cannot, and vice versa. Finally, we apply the derived convergence conditions to three popular contact data sets available in the literature (Cambridge, Infocom, and RollerNet), assessing the convergence of each class of forwarding protocols in these three cases
Characterization and identification of hidden rare variants in the human genome
Get PDFBackgroundBy examining the genotype calls generated by the 1000 Genomes Project we discovered that the human reference genome GRCh37 contains almost 20,000 loci in which the reference allele has never been observed in healthy individuals and around 70,000 loci in which it has been observed only in the heterozygous state.ResultsWe show that a large fraction of this rare reference allele (RRA) loci belongs to coding, functional and regulatory elements of the genome and could be linked to rare Mendelian disorders as well as cancer. We also demonstrate that classical germline and somatic variant calling tools are not capable to recognize the rare allele when present in these loci. To overcome such limitations, we developed a novel tool, named RAREVATOR, that is able to identify and call the rare allele in these genomic positions. By using a small cancer dataset we compared our tool with two state-of-the-art callers and we found that RAREVATOR identified more than 1,500 germline and 22 somatic RRA variants missed by the two methods and which belong to significantly mutated pathways.ConclusionsThese results show that, to date, the investigation of around 100,000 loci of the human genome has been missed by re-sequencing experiments based on the GRCh37 assembly and that our tool can fill the gap left by other methods. Moreover, the investigation of the latest version of the human reference genome, GRCh38, showed that although the GRC corrected almost all insertions and a small part of SNVs and deletions, a large number of functionally relevant RRAs still remain unchanged. For this reason, also future resequencing experiments, based on GRCh38, will benefit from RAREVATOR analysis results. RAREVATOR is freely available at http://sourceforge.net/projects/rarevator
An approach to high frequency monitoring of lakes: the SAILING and PITAGORA projects
Get PDFRecent developments in sensor technology allow highresolution monitoring of lakes and reservoirs from sensor based systems such as buoys and platforms. The data collected by these systems may be provided to end-users by web-based technology and in this way be readily available for both advanced users (e.g. researchers) and citizens. With respect to traditional monitoring, based on discrete samples, high frequency data may resolve diel or short-term events and detect horizontal and vertical patterns in large deep lakes. Starting in 2014, we assembled a multi-parameter measuring system, adaptable to specific needs and implementable with different type of sensors. This system was initially tested on a sailing boat, in the framework of the SAILING project (Sensor-based Assessment on In Lake processes and water quality - Scientific INvestigation and Growing environmental awareness): two monitoring campaigns were performed, on Lake Maggiore (during 2014) and Orta (during 2015), with the aim of measuring basic limnological parameters (water temperature, pH, conductivity, dissolved oxygen) in surface water with high temporal and spatial frequency. Successively, through the PITAGORA project (Platform of interoperable technology for the acquisition, management and organization of environmental data), a similar measuring system was installed on a couple of buoys, deployed in both the two lakes. In this paper we describe the approach we used in the development of these sensor based systems and present some preliminary results obtained from the analysis of high frequency data. Results highlight the usefulness of these data in detecting processes that occur on very short time scales, such as those driven by rapid changes in meteorological condition. These activities have been performed in the framework of the EU COST Action NETLAKE (Networking Lake Observatories in Europe), aiming to build a network of sites and individuals to support the development and deployment of sensor-based systems in lakes and reservoirs
Il progetto SISTO "SIstema di Sorveglianza TOssine algali"
No full textNot availableDescrizione del progetto SIST
Rapid and highly variable warming of lake surface waters around the globe
No full textIn this first worldwide synthesis of in situ and satellite-derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean?=?0.34?C decade?\u271) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors-from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72?C decade?\u271) to ice-free lakes experiencing increases in air temperature and solar radiation (0.53?C decade?\u271). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes
Repeatability estimation of torque and thrust results in open water tests as a function of the Reynolds number
Get PDFAccording to current European regulations for calculating measurement uncertainty, besides the computation of sensibility coefficients by, for example, OFAT tests, it\u27s useful to evaluate the own repeatability of measurement device and technique, in order to estimate the influence of the not controlled parameters. The aim of the present work is to show that repeatability of open water test results depends strongly on the performed Reynolds number. A large set of tests carried out on four screws models, with different shapes, diameters and blades numbers (for a total of 627 experimental data), has shown that the coefficients of variation of torque and thrust measurements, as well as standard deviation of hydrodynamic coefficients KQ and KT, decrease if Reynolds number increases, with a trend well fitted by a rational function like kx-a. Results show also that, if Reynolds number is about 750.000, standard deviations of torque and thrust are about 0.5% of the obtained measures, as well as those of KQ and KT. In addition to what already shown by ITTC (International Towing Tank Conference) Procedures, this conclusion provides useful information about the minimum Reynolds number at which to perform open water tests in order to limit the uncertainty intervals
Indagini su DDT e sostanze pericolose nell\u27ecosistema del Lago Maggiore. Programma 2013-2015. Rapporto annuale 2014. Riassunto
No full textNot availableRiassunto delle attivit? all\u27inizio del volume "Indagini su DDT e sostanze pericolose nell\u27ecosistema del Lago Maggiore. Programma 2013-2015. Rapporto annuale 2014"
Tassonomia molecolare per razionalizzare il monitoraggio biologico
Get PDFSpecies identification for most ecological and applied purposes (e.g. biological monitoring, environmental assessment, etc.) is performed through the analysis of morphological features of the organisms collected in the wild and sorted individually. There are growing evidences that several complexes of cryptic species (i.e. species that cannot be identified from morphology) exist in the zooplankton, and that different cryptic species within a single morphological species may respond differently to environmental drivers, because they represent different evolutionary entities with different ecological adaptations. Such differences can represent serious hindrances to our understanding of biological drivers and correlates of biodiversity if the species complexes are not solved. I will report few examples from on-going analyses on aquatic and limno-terrestrial rotifers to support such scenario and provide suggestions on how molecular tools could provide useful avenues to get pass such impasse
Occurrence and mass development of Mougeotia Spp. (Zygnemataceae) in large, deep lakes
Get PDFOver the last decades, mass developments by the filamentous conjugating green alga Mougeotia have been followed in three large peri-alpine lakes(Lake Geneva, Lake Garda, Lake Maggiore) and in the sub-tropical Lake Kinneret. The aim of this study is to highlight annual and interannual patterns of Mougeotia biomass in the studied lakes and select key environmental parameters that may favour and maintain its mass development. Our results confirm former studies that planktic Mougeotia favours meso-oligotrophic conditions and becomes dominant when annual mean total phosphorus concentrations in the epilimnion fall below 20 ?gl-1. This triggering factor has effect with interactions of other environmental circumstances such as the water column stability. Physiological and morphological features of the taxon make it a successful competitor under stratified conditions. Results also showed that in three out of the four studied lakes, the annual peak was higher when the annual population development started earlier. Focusing on Lake Geneva, depth and strength of the thermocline, as well as wind speed in the beginning of summer that can cause nutrient replenishment and mix the epilimnion are key factors in the blooming of the taxon
Mitochondrial and nuclear diversity in the green oak leaf roller Tortrix viridana L. (Lepidoptera, Tortricidae) from Sardinia
Get PDFThe Green oak leaf roller Tortrix viridana is one of the most harmful pest of the Palearctic oaks. The young larvae of T. viridana develop inside the flushing buds and their egg hatch is synchronized with the bud burst of the oaks. The aim of the study was to investigate the genetic structure and variation of mitochondrial and nuclear loci in Sardinian populations associated with deciduous (Quercus pubescens) and evergreen (Q. suber and Q. ilex) oaks. We performed multilocus analyses (COI, COII mitochondrial genes and eight microsatellites) in about two hundreds individuals collected on all the three oak species coming from the most important forest districts in Sardinia Island, Italy. The populations were also characterized by egg hatching, after comparison in semi-field tests for egg development. Eighty-five mitochondrial haplotypes were found, with three ones shared among all populations, except the most southern one. A high haplotype diversity (H =0.90) and a low nucleotide diversity (? =0.003) have been observed. Microsatellites were highly variable with alleles ranging from 4 to 56 for locus and polymorfic information content values varying from 0.510 to 0.945. AMOVA tests were performed by structuring samples in different groups (geographic districts/oak species/egg development). The highest values of Fixation indexes resulted grouping populations according to early or late egg hatching. Furthermore, we tested for sex-biased dispersal, estimating pairwise FST, FIS, and relatedness r at nuclear loci separately for the sexes. We produced evidence for non random patterns of gene flow probably mediated by male biased dispersal, with values significantly higher in females than in males and females the phylopatric sex. In support of a male biased dispersal, nuclear and mitochondrial markers provided different results in the matter of genetic structure, with mitochondrial loci, unlike microsatellites, highlighting significant differentiation levels among populations