The anatomy of a Clustering Engine for Web Snippets

Recently there has been a surge of commercial interest about novel IR-tools, like Vivisimo or Groxis, that support the user of a search engine in his/her query formulation and query refinement. The basic idea is that the snippets returned by the search engine are grouped into clusters which are then organized in a hierarchy whose nodes are properly labeled via meaningful sentences. Each sentence must capture the "theme" of the snippets contained into the cluster it labels. This way the user is provided with a small, but intelligible, picture of the query answers at various levels of details. Despite this commercial interest, we found just four scientific papers on this topic. None of them achieved results comparable to Vivisimo, that actually represents the state-of-the-art. In the present paper we address this problem in its full generality: labels of variable length for denoting the clusters, labels drawn from the Web snippets as non contiguous sequences of terms, clusters possibly overlapping and organized within a hierarchy. We achieve this results by means of an algorithmic approach that exploits some innovative ideas, at least from the academic side

Comparison of Krylov Subspace Methods on the PageRank Problem

PageRank algorithm plays a very important role in search engine technology and consists in the computation of the eigenvector corresponding to the eigenvalue one of a matrix whose size is now in the billions. The problem incorporates a parameter $\alpha$ that determines the difficulty of the problem. In this paper, the effectiveness of stationary and non stationary methods are compared on some portion of real web matrices for different choices of $\alpha$. We see that stationary methods are very reliable and more competitive when the problem is well conditioned, that is for small values of $\alpha$. However, for large value of the parameter $\alpha$ the problem becomes more difficult and methods such as preconditioned BiCGStab or restarted preconditioned GMRES become competitive with stationary methods in terms of Mflops count as well as in number of iterations necessary to reach convergence

Psychological assessment

Psychological Assessment. Evaluation of the family within the systemic approach. The relational systemic approach allows understanding of the symptom within the meaningful context of the family and identifies a mutual influence of the patient and the interactive context. An evaluation of a family system should allow improvement of knowledge about the points of strength and vulnerability of the patient and his or her family'. 'Evaluation is intervention. The systemic diagnosis is linked to the feedback that derives from meeting the family. The evaluation, the intervention and the diagnosis do not appear to be different and neatly distinguished phases, but they are all embedded within the same framework represented by the meeting with the family. The task of the therapist is not to discriminate the authenticity of the symptoms shown by the patient, as to start focusing on the shared and explicit explanation in order to “deconstruct” the symptom and to widen the maps through which the family interpret reality. The ideal unit of evaluation includes all the family members who are part of the problem. The evaluation should take into account two levels of investigation: the history of the symptomatic behaviour and the history of the nuclear and origin family. The therapist has to draw attention to the communicative style, the ways in which the family face their problems and developmental tasks, the distribution of roles and functions. It is necessary to verify whether or not opinions about the symptom are shared by the family, the circulation of unrecognized messages and emotions has to be regarded as the foundation of the symptom. The therapist has to take into account a synchronic level of interactive and communicative models and a diachronic level of individual and collective histories, and the phase of the life cycle that the family is going through. The relational complexity increases further with the investigation into the extended family, the multigenerational context can rep¬resent the diagnostic tool and the symptom becomes the product of the intergenerational history. Once the phase of evaluation has been ter¬minated, it is useful to build a new definition of what has emerged, for and with the family. The relational context also includes the therapist’s position'. 'The specific case of adolescence. Adolescence represents a basic moment for the growth of the system, the family, who has to transform the previous organization of role, functions and relationships, and adopt a more functional one, a process of co-evolution concerning both the boy or girl and the family. The adolescent feels the necessity to become independent from the parents, but at the same time he or she needs to count on them. The adolescent’s ‘symptomatic’ attitudes may be seen as the proposal of an autonomous identity, or that the bond with the parents has not been broken by this difference, the adolescent’s expectation is that the bond should be enriched and transformed by the difference itself, without undergoing traumatic and irreversible disruptions. The problems of adolescence may be related to the integration of different levels of reality, in which individual, familiar and social aspects have to be connected and contemporaneously taken into consideration. For this reason, family therapy may be a likely solution in adolescence. An integrated individual and familiar approach is the most suitable indication for adolescent disorders, both in diagnostic and in therapeutic terms

Five Years of Dust Episodes at the Southern Italy GAW Regional Coastal Mediterranean Observatory: Multisensors and Modeling Analysis

The Mediterranean area is a climate-change hotspot because of the natural and anthropogenic pollution pressure. The presence of natural aerosols, such as dust, influences solar radiation and contributes to the detection, in storm episodes, of significant concentrations of PM10 in Southern Italy, where generally fresh and clean air is due to local circulation, and particulate matter concentrations are very low. We present the results of medium-term observations (2015–2019) at Lamezia Terme GAW (Global Atmospheric Watch) Regional Observatory, with the purpose of identifying the dust incursion events by studying the aerosol properties in the site. To achieve this goal, the experimental data, collected by several instruments, have been also correlated with the large-scale atmospheric patterns derived by the ERA5 reanalysis dataset, in order to study the meteorological conditions that strongly influence dust outbreaks and their spatio-temporal behavior. An intense dust-outbreak episode, which occurred on 23–27 April 2019, was chosen as a case study; a detailed analysis was carried out considering surface and column optical properties, chemical properties, large-scale pattern circulation, air-quality modeling/satellite products, and back-trajectory analysis, to confirm the capability of the modeled large-scale atmospheric fields to correctly simulate the conditions mainly related to the desert dust-outbreak events