Bound and exact methods for assessing link vulnerability in complex networks

Assessing network systems for failures is critical to mitigate the risk and develop proactive responses. In this paper, we investigate devastating consequences of link failures in networks. We propose an exact algorithm and a spectral lower-bound on the minimum number of removed links to incur a significant level of disruption. Our exact solution can identify optimal solutions in both uniform and weighted networks through solving a well-constructed mixed integer program. Also, our spectral lower-bound derives from the Laplacian eigenvalues an estimation on the vulnerability of large networks that are intractable for exact methods. Through experiments on both synthetic and real-world networks, we demonstrate the efficiency of the proposed methods.     

外语能力磨蚀的性别差异初探

对300余名大学生进行了英语阅读和听力测试,并从中随机抽取男女生各50名进行了写作测试,得出如下结论:(1)外语磨蚀程度存在明显的性别差异;(2)男女生在深度阅读、短对话听力以及段落听力方面的磨蚀差异不显著;(3)女生在快速阅读能力方面的磨蚀程度明显超过男生;(4)女生写作能力在切题性、连贯性以及清楚性方面的磨蚀程度显著大于男生,而在语言的正确性方面的磨蚀没有明显超过男生.     

泰语中潮州话借词及其词义嬗变说略

潮州人移居泰国 ,促使彼此语言与文化相互影响。泰语从潮州话借入许多词语 ,这些借词绝大多数仍在使用 ,少部分因社会环境改变而消失 ,还有部分因不同原因词义发生嬗变     

Increased prevalence of erectile dysfunction (ED): Results of the second epidemiological study on sexual activity and prevalence of ED in Thai males

Objective.?The aim of this study is to investigate changes in sexual activity and the prevalence of erectile dysfunction (ED) in Thai males. In addition, the treatment-seeking behaviour of Thai patients suffering from ED is also investigated.

Materials and methods.?In a cross sectional study using a standardized questionnaire with a multi-stage stratified random sampling, 2,269 men aged 40–70 were interviewed. The questionnaire was designed to investigate the effects of socioeconomic factors, medical conditions and unhealthy lifestyles on the development of ED. Furthermore, the questionnaire was designed to characterize the treatment-seeking behaviour of Thai patients suffering from ED.

Results.?Compared to the first report dated the year 2000, the prevalence of ED has increased from 37.5% to 42.18%. In terms of socioeconomic factors, the highest prevalence of ED was observed among unemployed men (78.51%). Prostatism and/or prostatitis (Odd ratios (OR) = 2.02) and long histories of smoking (more than 30 years, OR = 2.36) were identified as statistically significant risk factors for ED, with p-values of <0.001. It is important to notice that 38.78% of the ED patients wanted to discuss their problem with spouses or partners. Three quarters of the ED patients (74.54%) preferred oral medication as therapy.

Conclusions.?The epidemiology of ED in Thailand is changing. An increased prevalence of ED does require further epidemiological studies on a regular basis in order to better understand the etiology of ED and look for measures (such as education) to counter the disease.     

Prevalence of sarcopenia and its association with functional and nutritional status among male residents in a nursing home in Turkey

Introduction The Aging Male Symptoms' (AMS) scale was designed as a health-related quality of life (QoL) scale and standardized as a self-administered scale, first, to assess symptoms of aging (independent from those which are disease-related) between groups of males under different conditions, second, to evaluate the severity of symptoms/QoL over time, and, third, to measure changes pre- and post-androgen replacement therapy. The scale is in widespread use (17 languages currently available) and a recent review of methodological data documented good psychometric characteristics and ability as a clinical utility. This paper describes test characteristics of the AMS (positive and negative predictive values), taking two internationally established and published screening scales for androgen deficiency as the available standard.

Method A sample of 150 German males aged 40–69 years completed the AMS scale and two screening scales for androgen deficiency: the ADAM scale of Morley and colleagues and the screener of Smith and colleagues. The technique of a computer-assisted telephone interview was applied.

Result The comparison of the AMS with the two screening instruments for androgen deficiency showed sufficiently good compatibility despite conceptual differences. The AMS scale sufficiently predicted the results of the two screening instruments. A positive predictive value of 92% and a negative predictive value of 50% were found regarding the ADAM scale. The respective figures regarding Smith's screener were 65% and 49% for positive and negative predictive values, respectively.

Conclusion The AMS scale obviously measures a similar phenomenon as the two established and widely used screeners for androgen deficiency, although it was not developed as a screening instrument.     

A comparison of bootstrap approaches for estimating uncertainty of parameters in linear mixed‐effects models

A version of the nonparametric bootstrap, which resamples the entire subjects from original data, called the case bootstrap, has been increasingly used for estimating uncertainty of parameters in mixed‐effects models. It is usually applied to obtain more robust estimates of the parameters and more realistic confidence intervals (CIs). Alternative bootstrap methods, such as residual bootstrap and parametric bootstrap that resample both random effects and residuals, have been proposed to better take into account the hierarchical structure of multi‐level and longitudinal data. However, few studies have been performed to compare these different approaches. In this study, we used simulation to evaluate bootstrap methods proposed for linear mixed‐effect models. We also compared the results obtained by maximum likelihood (ML) and restricted maximum likelihood (REML). Our simulation studies evidenced the good performance of the case bootstrap as well as the bootstraps of both random effects and residuals. On the other hand, the bootstrap methods that resample only the residuals and the bootstraps combining case and residuals performed poorly. REML and ML provided similar bootstrap estimates of uncertainty, but there was slightly more bias and poorer coverage rate for variance parameters with ML in the sparse design. We applied the proposed methods to a real dataset from a study investigating the natural evolution of Parkinson's disease and were able to confirm that the methods provide plausible estimates of uncertainty. Given that most real‐life datasets tend to exhibit heterogeneity in sampling schedules, the residual bootstraps would be expected to perform better than the case bootstrap. Copyright © 2013 John Wiley & Sons, Ltd.     

What's an Oscar worth?

This article examines the impact of an Academy Award nomination and award for best picture, best actor/actress, and best supporting actor/actress on a film's (i) market share of theaters, (ii) average revenue per screen, and (iii) its probability of survival. The model is estimated using weekly box-office data for a matched sample of nominated and non-nominated films. The results indicate substantial financial benefits for a nomination and award for best picture and best actor/actress. The structure of rewards is consistent with that found in two-stage, single-elimination tournaments.