Polytechnic University of Milan

About: Polytechnic University of Milan is a education organization based out in Milan, Italy. It is known for research contribution in the topics: Finite element method & Population. The organization has 18231 authors who have published 58416 publications receiving 1229711 citations. The organization is also known as: PoliMi & L-NESS.

Phoenix: DGA-Based Botnet Tracking and Intelligence ∗

Abstract: Modern botnets rely on domain-generation algorithms (DGAs) to build resilient command-and-control infrastructures. Given the prevalence of this mechanism, recent work has focused on the analysis of DNS traffic to recognize botnets based on their DGAs. While previous work has concentrated on detection, we focus on supporting intelligence operations. We propose Phoenix, a mechanism that, in addition to telling DGA- and non-DGA-generated domains apart using a combination of string and IP-based features, characterizes the DGAs behind them, and, most importantly, finds groups of DGA-generated domains that are representative of the respective botnets. As a result, Phoenix can associate previously unknown DGA-generated domains to these groups, and produce novel knowledge about the evolving behavior of each tracked botnet. We evaluated Phoenix on 1,153,516 domains, including DGA-generated domains from modern, well-known botnets: without supervision, it correctly distinguished DGA- vs. non-DGA-generated domains in 94.8 percent of the cases, characterized families of domains that belonged to distinct DGAs, and helped researchers “on the field” in gathering intelligence on suspicious domains to identify the correct botnet.

Horizontal data partitioning in database design

Abstract: In this paper the problem of horizontally partitioning data on a set of resources is considered.The main optimization parameter is the number of accesses performed by the application programs to different portions of data. The concepts which are required for the determination of relevant portions of data are defined and a methodology for determining the access parameters is proposed.The formulation of the general partitioning problem in 3 specific application environments is shown: distributed database design, file partitioning on a primary and a secondary memory and data distribution on different devices.It is shown that the analytical models of these specific applications use the parameters of the general formulation.

Smoking and life expectancy among HIV-infected individuals on antiretroviral therapy in Europe and North America.

Abstract: Background: Cardiovascular disease and non-AIDS malignancies have become major causes of death among HIV-infected individuals. The relative impact of lifestyle and HIV-related factors are debated. Methods: We estimated associations of smoking with mortality more than 1 year after antiretroviral therapy (ART) initiation among HIV-infected individuals enrolled in European and North American cohorts. IDUs were excluded. Causes of death were assigned using standardized procedures. We used abridged life tables to estimate life expectancies. Life-years lost to HIV were estimated by comparison with the French background population. Results: Among 17995 HIV-infected individuals followed for 79760 person-years, the proportion of smokers was 60%. The mortality rate ratio (MRR) comparing smokers with nonsmokers was 1.94 [95% confidence interval (95% CI) 1.56‐2.41]. The MRRs comparing current and previous smokers with never smokers were 1.70 (95% CI 1.23‐2.34) and 0.92 (95% CI 0.64‐1.34), respectively. Smokers had substantially higher mortality from cardiovascular disease, non-AIDS malignancies than nonsmokers [MRR 6.28 (95% CI 2.19‐18.0) and 2.67 (95% CI 1.60‐4.46), respectively]. Among 35-year-old HIV-infected men, the loss of life-years associated with smoking and HIV was 7.9 (95% CI 7.1‐8.7) and 5.9 (95% CI 4.9‐ 6.9), respectively. The life expectancy of virally suppressed, never-smokers was 43.5 years (95% CI 41.7‐45.3), compared with 44.4 years among 35-year-old men in the background population. Excess MRRs/1000 person-years associated with smoking increased from 0.6 (95% CI ‐1.3 to 2.6) at age 35 to 43.6 (95% CI 37.9‐49.3) at age at least 65 years. Conclusion: Well treated HIV-infected individuals may lose more life years through smoking than through HIV. Excess mortality associated with smoking increases markedly with age. Therefore, increases in smoking-related mortality can be

Extended finite element method for quasi‐brittle fracture

Abstract: A methodology for the simulation of quasi-static cohesive crack propagation in quasi-brittle materials is presented. In the framework of the recently proposed extended finite element method, the partition of unity property of nodal shape functions has been exploited to introduce a higher-order displacement discontinuity in a standard finite element model. In this way, a cubic displacement discontinuity, able to reproduce the typical cusp-like shape of the process zone at the tip of a cohesive crack, is allowed to propagate without any need to modify the background finite element mesh. The effectiveness of the proposed method has been assessed by simulating mode-I and mixed-mode experimental tests. Copyright © 2003 John Wiley & Sons, Ltd.