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We study the generalized min sum set cover (GMSSC) problem, wherein given a collection of hyperedges E with arbitrary covering requirements {ke ∈ Z+ : e ∈ E}, the goal is to find an ordering of the vertices to minimize the total cover time of the hyperedges; a hyperedge e is considered covered by the first time when ke many of its vertices appear in the ordering. We give a 4.642 approximation algorithm for GMSSC, coming close to the best possible bound of 4, already for the classical special case (with all ke = 1) of min sum set cover (MSSC) studied by Feige, Lovász and Tetali [11], and improving upon the previous best known bound of 12.4 due to Im, Sviridenko and van der Zwaan [20]. Our algorithm is based on transforming the LP solution by a suitable kernel and applying randomized rounding. This also gives an LP-based 4 approximation for MSSC. As part of the analysis of our algorithm, we also derive an inequality on the lower tail of a sum of independent Bernoulli random variables, which might be of independent interest and broader utility. Another well-known special case is the min sum vertex cover (MSVC) problem, in which the input hypergraph is a graph (i.e., |e| = 2) and ke = 1, for every edge e ∈ E. We give a 16/9 ' 1.778 approximation for MSVC, and show a matching integrality gap for the natural LP relaxation. This improves upon the previous best 1.999946 approximation of Barenholz, Feige and Peleg [6]. (The claimed 1.79 approximation result of Iwata, Tetali and Tripathi [21] for the MSVC turned out have an unfortunate, seemingly unfixable, mistake in it.) Finally, we revisit MSSC and consider the lp norm of cover-time of the hyperedges. Using a dual fitting argument, we show that the natural greedy algorithm simultaneously achieves approximation guarantees of (p + 1)1+1/p, for all p ≥ 1, giving another proof of the result of Golovin, Gupta, Kumar and Tangwongsan [13], and showing its tightness up to NP-hardness. For p = 1, this gives yet another proof of the

We study the generalized min sum set cover (GMSSC) problem, wherein given a collection of hyperedges E with arbitrary covering requirements {ke ∈ Z+ : e ∈ E}, the goal is to find an ordering of the vertices to minimize the total cover time of the hyperedges; a hyperedge e is considered covered by the first time when ke many of its vertices appear in the ordering. We give a 4.642 approximation algorithm for GMSSC, coming close to the best possible bound of 4, already for the classical special case (with all ke = 1) of min sum set cover (MSSC) studied by Feige, Lovász and Tetali [11], and improving upon the previous best known bound of 12.4 due to Im, Sviridenko and van der Zwaan [20]. Our algorithm is based on transforming the LP solution by a suitable kernel and applying randomized rounding. This also gives an LP-based 4 approximation for MSSC. As part of the analysis of our algorithm, we also derive an inequality on the lower tail of a sum of independent Bernoulli random variables, which might be of independent interest and broader utility. Another well-known special case is the min sum vertex cover (MSVC) problem, in which the input hypergraph is a graph (i.e., |e| = 2) and ke = 1, for every edge e ∈ E. We give a 16/9 ' 1.778 approximation for MSVC, and show a matching integrality gap for the natural LP relaxation. This improves upon the previous best 1.999946 approximation of Barenholz, Feige and Peleg [6]. (The claimed 1.79 approximation result of Iwata, Tetali and Tripathi [21] for the MSVC turned out have an unfortunate, seemingly unfixable, mistake in it.) Finally, we revisit MSSC and consider the lp norm of cover-time of the hyperedges. Using a dual fitting argument, we show that the natural greedy algorithm simultaneously achieves approximation guarantees of (p + 1)1+1/p, for all p ≥ 1, giving another proof of the result of Golovin, Gupta, Kumar and Tangwongsan [13], and showing its tightness up to NP-hardness. For p = 1, this gives yet another proof of the

Aims: Curative-intent radiotherapy (RT) or chemoradiation (CRT) of squamous cell carcinoma of the head and neck (HNSCC) produces high survival rates, but is associated with substantial toxicity. However, there are no commonly accepted quality metrics for early mortality in radiation oncology. To assess the applicability of early mortality as a clinical quality indicator, this study investigated the temporal distribution, risk factors and trends of 90- and 180-day overall and non-cancer mortality in a nationwide cohort of HNSCC patients treated with RT/CRT. Materials and methods: Information on all HNSCC patients treated with curative-intent RT/CRT in Denmark between 2000 and 2017 was obtained from the national Danish Head and Neck Cancer Group clinical database. Deaths in patients with residual or recurrent disease after RT/CRT were classified as cancer-related. Possible risk factors were investigated using logistic regression analysis. Results: Data from 11 419 patients were extracted. In total, 90- and 180-day mortality risks were 3.1% and 7.1%, respectively. There was a uniform temporal distribution of 180-day mortality. In multivariable analysis, increasing age, stage, performance status, earlier treatment year and hypopharyngeal cancer were significantly associated with an increased risk (P < 0.05). Risk factor estimates were comparable for 90- versus 180-day mortality as well as for overall versus non-cancer mortality. Between 2000 and 2017 there was a significant decrease in 180-day mortality, which was driven by a reduction in cancer-related events. Conclusion: The distribution of 180-day overall and non-cancer mortality did not indicate a well-defined early high-risk period. Moreover, risk factor estimates were highly similar across risk periods and groups. Taken together, our findings question the applicability of early mortality as a standard metric for treatment-associated toxicity.

© 2017 IEEE. Small drones are a rising threat due to their possible misuse for illegal activities, in particular smuggling and terrorism. The project SafeShore, funded by the European Commission under the Horizon 2020 program, has launched the 'drone-vs-bird detection challenge' to address one of the many technical issues arising in this context. The goal is to detect a drone appearing at some point in a video where birds may be also present: the algorithm should raise an alarm and provide a position estimate only when a drone is present, while not issuing alarms on birds. This paper reports on the challenge proposal, evaluation, and results1.

© 2017 IEEE. Small drones are a rising threat due to their possible misuse for illegal activities, in particular smuggling and terrorism. The project SafeShore, funded by the European Commission under the Horizon 2020 program, has launched the 'drone-vs-bird detection challenge' to address one of the many technical issues arising in this context. The goal is to detect a drone appearing at some point in a video where birds may be also present: the algorithm should raise an alarm and provide a position estimate only when a drone is present, while not issuing alarms on birds. This paper reports on the challenge proposal, evaluation, and results1.

© 2017, International Society of Behavioral Medicine. Purpose: Understanding and increasing awareness on individual risk for HIV infection as well as HIV risk perception’s effects on different behavioral outcomes for people who inject drugs (PWID) is important for policymaking and planning purposes. The objectives of the present study were to determine whether HIV risk perception was associated with greater injection and sexual risk-taking behaviors among PWIDs. Method: We surveyed 460 PWID in Kermanshah regarding their demographic characteristics, sexual risk behaviors, HIV risk perception, and drug-related risk behaviors in the month prior to the study. Three classes of HIV risk perception were identified using ordinal regression to determine factors associated with HIV risk perception. Results: Study participants were categorized as follows: “low� (n = 100, 22%), “moderate� (n = 150, 32%), and “high� (n = 210, 46%) risk perception for becoming infected with HIV. The odds of categorizing as “high� risk for HIV was significantly greater in PWID that reported unprotected sex (adjusted odds ratio (AOR) 2.4, p value 0.02), receptive syringe sharing (AOR 1.8, p value 0.01), and multiple sex partners (AOR 1.4, p value 0.03). PWID who reported unprotected sex had 2.7 times the odds of “high� risk perception when compared to PWID with “low� risk perception. Conclusion: Findings show that PWID could rate their HIV risk with acceptable accuracy. Additionally, perceived HIV risk was associated with many risk factors for transmission of HIV, emphasizing the importance of developing targeted prevention and harm reduction programs for all domains of risk behaviors, both sexual and drug-related use.

© 2017 Taylor & Francis Group, LLC. Background: Characteristics and behaviors of early-onset injection drug users are under studied topics in Iran. This study aimed to identify and compare the demographic characteristics as well as the drug using behaviors of early-onset and late-onset injection drug users in Kermanshah, West Iran. Methods: In this cross-sectional study using snowball and convenience sampling, we recruited 450 people during the Fall of 2014 from two drop in centers in Kermanshah, Iran. We collected data through face-to-face interviews. Early-onset injection is defined as whether the person reported their first injection at 22 years of age or younger. Subsequently, late-onset injection is defined as 23 years of age or older. We compared the characteristics of the two groups through both univariate and multiple logistic analyses. Results: Overall, 54% (CI 95%: 44.3%, 62.2%) were early injectors. After controlling for low socioeconomic status, initiation of drug use at a young age, multiple drug use and methamphetamine use were all significantly associated with a higher likelihood of early-onset injection. Additionally, early-onset injection was associated with recent syringe borrowing (OR = 2.6, p = 0.001), recent syringe lending (OR = 1.4, p = 0.01), recent cooker sharing (OR = 3.2, p = 0.01) and injecting two or more times a day (OR = 2.2, p = 0.04). Conclusion: Early-onset injectors were more likely to report a lower socioeconomic status, initiation of first drug use at a younger age, using methamphetamine alongside polydrug use, and engaging in higher risk taking behaviors like borrowing needles. With these associations, the study emphasizes the need for drug-prevention programs to focus on the transition to injection drug use at younger ages.

© 2017 Taylor & Francis Group, LLC. Background: Needle and Syringe Programs (NSP) have been implemented in Iran since 2002. The primary aim of NSP is to prevent blood-borne virus transmission by providing sterile injecting equipment and information on safer injection practices. However, while NSP has been implemented in Iran for more than a decade, only a limited number of studies have evaluated the effect access to NSP has in reducing risk behaviors among people who inject drugs (PWIDs).Methods: Between September and December 2014 we used snow ball sampling to recruit PWID from Kermanshah for a cross-sectional survey. Participants completed a face-to-face interview and provided information on the frequency of injection and drug-related risk behaviors such as sharing (borrowing or lending) of previously used syringes/needles and the number of injecting partners with whom they have shared syringes/needles in the two months prior to interview. Correlation between drug-related risk behaviors and ability to access NSPs was assessed by bivariate and multiple logistic regression through the estimation of odds ratios (OR) and 95% confidence intervals (95% CI).Results: Of 500 PWIDs in this study, 18%, 36% and 46% reported low, medium and high ability to access NSPs in the two months prior to interview, respectively. The odds of receptive syringe sharing among people with low-access was 3.5 times the odds of people with high-access when adjusted for covariates and remained statistically significant (adjusted odds ratio (AOR): 3.5, 95%CI 1.4–7.7). The relationship between access to NSP and use of sterile-injecting equipment was not statistically significant. The AOR for outcomes like paraphernalia sharing (AOR: 2.5, 95%CI: 0.6–4.6, p-value: 0.6) was not statistically significant.Conclusions: Similar to the previous research in international settings, this study found that PWID who reported to have more access to needle and syringe programs were less likely to use a syringe af