Towards better understanding of gradient-based attribution methods for Deep Neural Networks

Understanding the flow of information in Deep Neural Networks (DNNs) is a challenging problem that has gain increasing attention over the last few years. While several methods have been proposed to explain network predictions, there have been only a few attempts to compare them from a theoretical perspective. What is more, no exhaustive empirical comparison has been performed in the past. In this work, we analyze four gradient-based attribution methods and formally prove conditions of equivalence and approximation between them. By reformulating two of these methods, we construct a unified framework which enables a direct comparison, as well as an easier implementation. Finally, we propose a novel evaluation metric, called Sensitivity-n and test the gradient-based attribution methods alongside with a simple perturbation-based attribution method on several datasets in the domains of image and text classification, using various network architectures.Comment: ICLR 201

Social Dilemmas and Cooperation in Complex Networks

In this paper we extend the investigation of cooperation in some classical evolutionary games on populations were the network of interactions among individuals is of the scale-free type. We show that the update rule, the payoff computation and, to some extent the timing of the operations, have a marked influence on the transient dynamics and on the amount of cooperation that can be established at equilibrium. We also study the dynamical behavior of the populations and their evolutionary stability.Comment: 12 pages, 7 figures. to appea

The impact of nonalcoholic fatty liver disease on renal function in children with overweight/obesity

The association between nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease has attracted interest and attention over recent years. However, no data are available in children. We determined whether children with NAFLD show signs of renal functional alterations, as determined by estimated glomerular filtration rate (eGFR) and urinary albumin excretion. We studied 596 children with overweight/obesity, 268 with NAFLD (hepatic fat fraction >= 5% on magnetic resonance imaging) and 328 without NAFLD, and 130 healthy normal-weight controls. Decreased GFR was defined as eGFR < 90 mL/min/1.73 m(2). Abnormal albuminuria was defined as urinary excretion of >= 30 mg/24 h of albumin. A greater prevalence of eGFR < 90 mL/min/1.73 m2 was observed in patients with NAFLD compared to those without liver involvement and healthy subjects (17.5% vs. 6.7% vs. 0.77%; p < 0.0001). The proportion of children with abnormal albuminuria was also higher in the NAFLD group compared to those without NAFLD, and controls (9.3% vs. 4.0% vs. 0; p < 0.0001). Multivariate logistic regression analysis revealed that NAFLD was associated with decreased eGFR and/or microalbuminuria (odds ratio, 2.54 (confidence interval, 1.16-5.57); p < 0.05) independently of anthropometric and clinical variables. Children with NAFLD are at risk for early renal dysfunction. Recognition of this abnormality in the young may help to prevent the ongoing development of the disease

Student mobility in higher education: Sicilian outflow network and chain migrations

The Italian public universities are subsidised within a competitive framework that awards excellence, efficiency, and the capacity of universities to attract students from Italian regions other than its own. However, repeated cuts to public spending has increased the well-known Italian North-South divide. The most important student mobility (SM) flow is from the Southern to the Central-Northern regions--a phenomenon that has been magnified by an increasing number of outgoing students from Sicily over the last decade. In this paper, we rely upon micro-data of university enrolment and students' personal records for three cohorts of freshmen, in order to investigate preferential patterns of SM from Sicily toward universities in other regions. Indeed, our main goal is to eventually reveal the existence of chain migrations, through which students from a particular geographical area move towards a particular destination. We consider 38 clusters aggregating the 390 Sicilian municipalities, based on geographical proximity and socio-economic criteria. The data from each cohort is represented as a tripartite network with three sets of nodes, namely, clusters of Sicilian municipalities, students, and universities. The tripartite network is projected in a bipartite weighted network of clusters and universities, which is, then, filtered, in order to obtain a statistically validated bipartite network (SBVN). The SBVNs of the three cohorts suggest the existence and evolution of chain migration patterns over time, which are also gender specific

A meta-analysis of survival rates of untreated patients in randomized clinical trials of hepatocellular carcinoma.

Knowing the spontaneous outcome of hepatocellular carcinoma (HCC) is important for designing randomized controlled trials (RCTs) of new therapeutic approaches; however, survival of patients in the absence of treatment is highly variable, and prognostic factors influencing outcomes are incompletely defined. The aims of this meta-analysis were to estimate the 1-year and 2-year survival rates of untreated HCC patients enrolled in RCTs of palliative treatments, and to identify prognostic factors. RCTs evaluating therapies for HCC with placebo or no-treatment arms were identified on MEDLINE through April 2009. Data were combined in a random effect model. Primary outcomes were 1-year and 2-year survival. Thirty studies met the inclusion criteria. The pooled estimates of the survival rates were 17.5% at 1 year (95% confidence interval [95%CI], 11%-27%; range, 0%-75%) and 7.3% at 2 years (95%CI, 3.9%-13%; range, 0%-50%). Heterogeneity among studies was highly significant (P < 0.0001) both for 1-year and 2-year survival, and persisted when RCTs were stratified according to all patient and study features. Through meta-regression, impaired performance status, Child-Pugh B-C class, and presence of portal vein thrombosis were all independently associated with shorter survival. Ascites was strongly linked to a worse outcome in intermediate/advanced Barcelona Clinic Liver Cancer stages. Conclusion: This meta-analysis confirms the heterogeneity of behavior of untreated HCC and provides a sound basis for stratifying patients with HCC according to expected survival in future trials of new anti-cancer agents

Physical–Mechanical and Mineralogical Properties of Fired Bricks of the Archaeological Site of Harran, Turkey

In this study, the physical–mechanical and mineralogical properties of bricks used in historical structures of the site of Harran, Turkey have been investigated. Harran was destroyed by the Mongol army, during the Turkish reconquest campaign around the 1260s. The remains of the buildings made of bricks and basalt/limestone were recently uncovered almost in their entirety. Several brick samples have been taken from the burial mound, the university, the city walls, the castle, and the great mosque. From the visual analyses, it was noted that the bricks have unique colors such as pottery, desert beige, and canyon. Physical analyses show that the absorption rates of the bricks are between 17.30–38.12%, their densities between 1.33–1.70 g/cm3, and porosities between 8.88–25.31%. For the mechanical analyses, the bending strengths have been found to be between 0.82–1.86 MPa and compressive strengths between 6.69–7.95 MPa. The thin-section images show that the bricks contain calcite, muscovite, and plagioclase quartz and pyroxene minerals