1,721,308 research outputs found
Non-crossing shortest paths in planar graphs with applications to max flow, and path graphs
Full text linkThis thesis is concerned with non-crossing shortest paths in planar graphs with applications to st-max flow vitality and path graphs.
In the first part we deal with non-crossing shortest paths in a plane graph G, i.e., a planar graph with a fixed planar embedding, whose extremal vertices lie on the same face of G. The first two results are the computation of the lengths of the non-crossing shortest paths knowing their union, and the computation of the union in the unweighted case. Both results require linear time and we use them to describe an efficient algorithm able to give an additive guaranteed approximation of edge and vertex vitalities with respect to the st-max flow in undirected planar graphs, that is the max flow decrease when the edge/vertex is removed from the graph. Indeed, it is well-known that the st-max flow in an undirected planar graph can be reduced to a problem of non-crossing shortest paths in the dual graph. We conclude this part by showing that the union of non-crossing shortest paths in a plane graph can be covered with four forests so that each path is contained in at least one forest.
In the second part of the thesis we deal with path graphs and directed path graphs, where a (directed) path graph is the intersection graph of paths in a (directed) tree. We introduce a new characterization of path graphs that simplifies the existing ones in the literature. This characterization leads to a new list of local forbidden subgraphs of path graphs and to a new algorithm able to recognize path graphs and directed path graphs. This algorithm is more intuitive than the existing ones and does not require sophisticated data structures
A Note on 3D Orthogonal Drawings with Direction Constrained Edges
No full textThe recent interest in three-dimensional graph drawing has been motivating studies on how to extend two-dimensional techniques to higher dimensions. A common 2D approach for computing an orthogonal drawing separates the task of defining the shape of the drawing from the task of computing its coordinates. First results towards finding a three-dimensional counterpart of this approach are presented by G. Di Battista, et al. [Graph Drawing (Proc. GD’00), Lecture Notes in Comput. Sci., vol. 1984, Springer, Berlin, 2001; Theoret. Comput. Sci. 289 (2002) 897], where characterizations of orthogonal representations of paths
and cycles are studied. In this paper we show that the characterization for cycles given by G. Di Battista, et al. [Theoret. Comput. Sci. 289 (2002) 897] does not immediately extend to even seemingly simple graphs.
La terapia batterica orale nell’ infezione da SARS-CoV2: nuove sfide in corso di pandemia
Full text linkSARS-CoV-2 may impact on host microbiota and gut inflammation, infecting intestinal epithelial cells. Furthermore, some patients after the resolution of the disease, experience symptoms associated with a syndrome known as Long-Covid characterized by symptoms such as fatigue, "brain fog", similar diffuse pains. The aim of this study was to compare the rate of mortality, the need of ICU hospitalization and the length of hospitalization in patients with severe COVID-19 pneumonia who received the best available therapy (BAT) vs. patients treated with BAT and supplemented with oral bacteriotherapy. We also analyzed the effect of probiotic supplementation in preventing chronic fatigue.
Methods: We performed an observational cohort study included 200 adults with COVID-19 pneumonia. All patients received therapeutic regimens including low molecular weight heparin plus one or more between hydroxychloroquine, azithromycin, antivirals, and Tocilizumab. Oral bacteriotherapy (OB) was used as complementary treatment. Subsequently, to evaluate the effect on chronic fatigue, a subgroup of 58 patients hospitalized for COVID-19 was analyzed. 24 (41.4%) received OB during hospitalization (OB+) while 34 (58.6%) taken only the standard treatment (OB–). Serum metabolomic profiling of patients has been performed at both hospital acceptance (T0) and discharge (T1). Six months after discharge, fatigue perceived by participants was assessed by administrating the Fatigue Assessment Scale.
Results: Out of the 200 patients, 112 received BAT without oral bacteriotherapy, and 88 BAT with oral bacteriotherapy. Crude mortality was 22%. In the group of patients treated with BAT plus oral bacteriotherapy 11% died as compared to 30% in the group of patients treated with BAT (p < 0.001). By multivariate analysis, age >65 years, C-Reactive Protein >41.8 mg/L, Platelets <150.000 mmc, and cardiovascular events were associated with the increased risk of mortality. Oral bacteriotherapy was associated with a reduced risk for death. From the group of 58 patients investigated for chronic fatigue, 70.7% reported fatigue while 29.3% were negative for such condition. The OB+ group showed a lower proportion of subjects reporting fatigue than the OB– one (p < 0.01). Furthermore, OB+ subjects were characterized by significantly increased concentrations of serum Arginine, Asparagine, Lactate opposite to lower levels of 3-Hydroxyisobutirate.
Discussion: this study suggests a possible role for oral bacteriotherapy in the management of patients hospitalized for COVID-19 pneumonia and point out how the administration of probiotics may prevent the development of chronic fatigue by impacting key metabolites involved in the utilization energy pathways
Scelta dei genitori sulle fonti di informazione relative alle vaccinazioni infantili. Uno studio trasversale in due Asl italiane
Full text link“Vaccine hesitancy” has been defined by the World Health Organization (WHO) as “delay in acceptance of vaccine despite the availability of vaccination services”. This definition also recognizes that vaccine hesitancy is complex and context specific, varying across time, place and vaccines and it is influenced by factors such as complacency, convenience and confidence. When it comes to childhood vaccination campaigns, this issue can lead to very problematic outcomes in terms of public health. A factor playing a fundamental role in this dynamic is the source of information considered by parents in the decision-making progress that leads to the acceptance or refusal of childhood vaccinations. Previous studies show how selecting an alternative source of information, as opposed to a conventional and institutional one, can result into major skepticism or even refuse of childhood vaccinations. An online questionnaire was administered anonymously to the parents of students attending elementary, middle and high schools in Rome and Turin, through the electronic register of the schools they belong to. Two validated tools were used: the Parent Attitudes about Childhood Vaccines Survey (PACVs), and the Health Literacy Vaccinale degli adulti in Italiano (HLVa- IT). In a third section, vaccination hesitancy in relation to COVID-19 was assessed. Univariate analysis and logistic regression models were built to identify predictors of the preferred sources of information on the topic. 2301 answers to the survey were collected from June to October 2021. 1127 came from parents in Rome (49%) and 1174 from parents based in Turin (51%). The majority of the respondents were mothers (81%), married (73%), with 2 or more children (70,5%). Most of the parents have a degree or post-degree education (59%) and have an employment (90%). The average age in the selected sample was 47.7 years (Std. dev. 6.4). Our logistic regression model showed that fathers were more prone than mothers to use alternative sources of information (p=0.001, OR 1.32 – 2.63). Moreover, a score >50 on the PACV scale (p=0.004, OR 1.4 – 5.6) was a strong predictor for choosing an alternative source of information. Other predictors that showed a statistical significance were the perceived quality of the healthcare system, the city parents were from, the child’s age, being atheist or agnostic and referring to be in need of more information about vaccinations. The HLVA-it filter questions showed that people who had never paid attention to information material about vaccination or that were never invited to get a vaccine were more inclined to use alternative sources of information
Minimum cloud and layer ignition temperatures of mixtures of combustible and inert dusts
No full textQuasi una mise en abyme. Ovvero, dei riverberi della parola
No full textContributo sugli scritti di critica teatrale di Giuseppe Liotta
Quasi una mise en abyme. Ovvero, dei riverberi della parola
No full textContributo sugli scritti di critica teatrale di Giuseppe Liotta
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