Social Search: retrieving information in Online Social Platforms -- A Survey

Social Search research deals with studying methodologies exploiting social information to better satisfy user information needs in Online Social Media while simplifying the search effort and consequently reducing the time spent and the computational resources utilized. Starting from previous studies, in this work, we analyze the current state of the art of the Social Search area, proposing a new taxonomy and highlighting current limitations and open research directions. We divide the Social Search area into three subcategories, where the social aspect plays a pivotal role: Social Question&Answering, Social Content Search, and Social Collaborative Search. For each subcategory, we present the key concepts and selected representative approaches in the literature in greater detail. We found that, up to now, a large body of studies model users' preferences and their relations by simply combining social features made available by social platforms. It paves the way for significant research to exploit more structured information about users' social profiles and behaviors (as they can be inferred from data available on social platforms) to optimize their information needs further

Latent Assimilation: assimilating data in a latent space of a surrogate model

Formulation of a new methodology that combines machine learning and data assimilation techniques. The methodology consists in using an Autoencoder to reduce the size of the input. In the latent space, a recurrent neural network (LSTM) is used as a surrogate for a dynamic system. The accuracy of the model is improved by using the Kalman Filter in the latent space which incorporates data (observation) collected by sensors, producing the updated state. The updated state is then reported in the original physical space by the decoder. The methodology was applied to a real test case

Rapid molecular evolution of human bocavirus revealed by Bayesian coalescent inference

Human bocavirus (HBoV) is a linear single-stranded DNA virus belonging to the Parvoviridae family that has recently been isolated from the upper respiratory tract of children with acute respiratory infection. All of the strains observed so far segregate into two genotypes (1 and 2) with a low level of polymorphism. Given the recent description of the infection and the lack of epidemiological and molecular data, we estimated the virus''s rates of molecular evolution and population dynamics. A dataset of forty-nine dated VP2 sequences, including also eight new isolates obtained from pharyngeal swabs of Italian patients with acute respiratory tract infections, was submitted to phylogenetic analysis. The model parameters, evolutionary rates and population dynamics were co-estimated using a Bayesian Markov Chain Monte Carlo approach, and site-specific positive and negative selection was also investigated. Recombination was investigated by seven different methods and one suspected recombinant strain was excluded from further analysis. The estimated mean evolutionary rate of HBoV was 8.6x10(-4)subs/site/year, and that of the 1st+2nd codon positions was more than 15 times less than that of the 3rd codon position. Viral population dynamics analysis revealed that the two known genotypes diverged recently (mean tMRCA: 24 years), and that the epidemic due to HBoV genotype 2 grew exponentially at a rate of 1.01year(-1). Selection analysis of the partial VP2 showed that 8.5% of sites were under significant negative pressure and the absence of positive selection. Our results show that, like other parvoviruses, HBoV is characterised by a rapid evolution. The low level of polymorphism is probably due to a relatively recent divergence between the circulating genotypes and strong purifying selection acting on viral antigens

Hepatitis B virus genotypes distribution in individuals with chronic HBV infection and in patients with HBV/HIV-1 co-infection living in Italy

Hepatitis B virus (HBV) strains isolated worldwide have been classified into 8 genomic groups (A to H) defined by an intergroup divergence of more than 8% in the complete genome sequence. The genotypes show a geographical pattern in their distribution and may influence the natural course of chronic HBV infection. To determine HBV distribution and correlation with particular risk behaviours among individuals living in Italy, the serum samples from 62 subjects with chronic HBV infection and 55 patients with HBV/HIV-1 co-infection were examined for the presence of HBV-DNA by amplifying a highly conserved S gene region through nested-PCR assay and for genotypes by sequence analysis of a 1182 bp fragment including entirely S, pre-S2 and partially pre-S1 regions. Ninety-eight out of 117 (83.8%) patients were HBV-DNA positive and all samples were classified by sequencing. Genotype D was the most prevalent both in chronic HBV infected (59.7%) and in HBV/HIV-1 co-infected (47.2%) patients, followed by genotype A (25.8% and 36.1%, respectively). Genotype F was detected in 7.2%, genotype G in 5.1%, while genotypes B, C and E in 1.0% respectively of the study population. Genotypes A, D, F and G were present in Italian-born subjects, whereas genotypes B, C and E were found in subjects from Asia and Africa. As regard to risk factors, we found a significative association between genotype D and parenteral route, whereas genotype A seems to be related to sexual route of transmission. Further investigations should be carried out on larger number of samples in order to better understand the HBV genotypes distribution in the Italian population

Peripheral blood HIV-1 DNA dynamics in antiretroviral-treated HIV/HCV co-infected patients receiving directly-acting antivirals.

Aim was to determine the dynamics of peripheral blood mononuclear cells (PBMC)- associated total HIV-1 DNA in successfully ART-treated HIV/HCV co-infected patients receiving DAA treatment and to explore possible virological hypotheses underlying the phenomenon.Longitudinal, single-centre study measuring total HIV-1 DNA before the start of DAA, at the end of treatment (EOT), and 3 months after treatment. Univariable and multivariable analyses were used to assess factors associated with HIV-1 DNA increase ≥0.5 Log copies/million PBMC. Episomal 2-LTR forms, residual HIV-1 viremia and proviral DNA quasispecies evolution were also investigated.119 successfully ART-treated HIV/HCV co-infected patients were included. Median baseline HIV-1 DNA was 3.84 Log copies/million PBMC (95%CI 3.49-4.05), and no significant variation with respect to baseline was found at EOT and after 3 months of DAA termination. In 17% of cases an increase ≥0.5 Log copies/million PBMC was observed at EOT compared to baseline. HIV-1 DNA increase was independently associated with lower baseline HIV-1 DNA, longer HIV suppression, raltegravir-based ART and previous exposure to interferon/ribavirin for HCV treatment. In none of the patients with HIV-1 DNA increase, 2-LTR forms were detected at baseline, while in 2 cases 2-LTR forms were found at EOT, without association with residual HIV-1 RNA viremia. No evidence of viral evolution was observed.In successfully ART-treated HIV/HCV co-infected patients receiving DAA, PBMC-associated total HIV-1 DNA was quite stable over time, but some patients showed a considerable increase at EOT when compared to baseline. A significantly higher risk of HIV DNA increase was found, in presence of lower cellular HIV reservoir at baseline. Activation of replicative-competent virus generating new rounds of viral replication seems unlikely, while mobilization of cell-associated HIV from tissue reservoirs could be hypothesized

La stagione neorealistica di Eduardo tra la scena e lo schermo

Il saggio si occupa di quella felice stagione del secondo dopoguerra durante la quale Eduardo scrisse i suoi capolavori teatrali e realizzò la maggior parte delle sue opere cinematografiche. Cerca inoltre di chiarie due equivoci che hanno inficiato una serena valutazione critica del suo rapporto con lo schermo. La prima è il contributo al “neorealismo”, inteso come uno schema prefissato a cui gli autori, come lo stesso Eduardo, dovevano attenersi. Il secondo equivoco è legato ad una vulgata che mette a confronto i due ambiti: la scena e lo schermo finendo per concludere che la sua figura di cineasta sia mediocre. Eduardo, in breve, diede un valido contributo alla stagione neorealista, nel cinema, non meno che nel teatro. Per quanto riguarda le sue capacità di attore e anche di regista, ad una più attenta e meditata analisi, si rivelano caratteri fin ad ora ignorati di originalità e resa espressiva

Virological and Immunological Outcomes of an Intensified Four-Drug versus a Standard Three-Drug Antiretroviral Regimen, Both Integrase Strand Transfer Inhibitor-Based, in Primary HIV Infection

The optimal therapeutic approach for primary HIV infection (PHI) is still debated. We aimed to compare the viroimmunological response to a four- versus a three-drug regimen, both INSTI-based, in patients with PHI. This was a monocentric, prospective, observational study including all patients diagnosed with PHI from December 2014 to April 2018. Antiretroviral therapy (ART) was started, before genotype resistance test results, with tenofovir/emtricitabine and either raltegravir plus boosted darunavir or dolutegravir. Cumulative probability of virological suppression [VS] (HIV-1 RNA< 40 cp/mL), low-level HIV-1 DNA [LL-HIVDNA] (HIV-1 DNA < 200 copies/106PBMC), and CD4/CD8 ratio ≥1 were estimated using Kaplan–Meier curves. Factors associated with the achievement of VS, LL-HIVDNA, and CD4/CD8 ≥ 1 were assessed by a Cox regression model. We enrolled 144 patients (95.8% male, median age 34 years): 110 (76%) started a four-drug-based therapy, and 34 (24%) a three-drug regimen. Both treatment groups showed a comparable high probability of achieving VS and a similar probability of reaching LL-HIVDNA and a CD4/CD8 ratio ≥1 after 48 weeks from ART initiation. Higher baseline HIV-1 RNA and HIV-1 DNA levels lowered the chance of VS, whereas a better preserved immunocompetence increased that chance. Not statistically significant factors associated with LL-HIVDNA achievement were found, whereas a higher baseline CD4/CD8 ratio predicted the achievement of immune recovery. In PHI patients, the rapid initiation of either an intensified four-drug or a standard three-drug INSTI-based regimen showed comparable responses in terms of VS, viral reservoir size, and immunological recovery

The scatterplot of baseline HIV-1 DNA levels and change between EOT and baseline.

<p>The scatterplot of baseline HIV-1 DNA levels and change between EOT and baseline.</p

Phylogenetic tree of HIV-1 C2V5 nucleotide clonal sequences of subject #53 during DAA therapy.

<p>The viral sequences at the various time points are indicated by different colours, see table insert. Bootstrap values ≥80% are indicated. Bars indicate p distance scale. In the insert mean diversity (number of nucleotide substitutions/site) of the sequences detected at different time points is reported.</p