The Stackelberg minimum spanning tree game on planar and bounded-treewidth graphs

The Stackelberg Minimum Spanning Tree Game is a two-level combinatorial pricing problem played on a graph representing a network. Its edges are colored either red or blue, and the red edges have a given fixed cost, representing the competitor’s prices. The first player chooses an assignment of prices to the blue edges, and the second player then buys the cheapest spanning tree, using any combination of red and blue edges. The goal of the first player is to maximize the total price of purchased blue edges. We study this problem in the cases of planar and bounded-treewidth graphs. We show that the problem is NP-hard on planar graphs but can be solved in polynomial time on graphs of bounded treewidth.     

执教中国

对一个西方人而言,在中国从事教育工作往往有这样一种感情经历：有时喜悦,有时沮丧,但总是魅力无穷。尽管文化上的差异十分明显,然而,也正是这种差异促进了师生之间的相互理解和相互尊重。这是我在东北师大、外交学院、南京大学执教以及在杭州师院随同美国大学生访问而得出的结论。 中国的高等教育虽然有了很大发展,但大学生占整体人口的比率相对于欧洲来说仍然很少,与美国相比则更少。仅这一因素,就使西方教师觉得中国学生很特别。一方面,这造就了一部分在传统衡量方式下学术能力和记忆能力表现都不错的学生。另一方面,正是这种…     

Psychological Distress as an Indicator of Co-Occurring Psychopathology among Treatment-Seeking Disordered Gamblers

Disordered gamblers frequently present with concurrent anxiety, depressive, personality, and substance use disorders, which may complicate treatment. Although there is a need for a thorough assessment, some questionnaires may prove lengthy for clients and clinicians. Thus, there is a need for brief screens for identifying co-occurring psychopathology. The present study sought to examine whether a brief, self-report measure of psychological distress could indicate the presence of co-occurring psychopathology among an outpatient sample of disordered gamblers. At intake, 69 participants completed self-report measures of distress and gambling symptomatology, a personality inventory, and a structured interview for the diagnostic criteria for disordered gambling. Gamblers with greater elevations of psychological distress evidenced greater severity of gambling pathology. Clinically significant elevations were present for symptoms of depression, deviancy, and anxiety, but not substance abuse. Greater scores of psychological distress significantly predicted elevations of depression, deviancy, and anxiety. Sensitivity and specificity were evaluated and the findings supported that an average psychological distress score of 16 corresponded with the presence of co-occurring psychopathology. Clinicians treating disordered gamblers should consider screening for co-occurring psychopathology with brief, self-report measures of psychological distress.     

Competing risk analysis in a large cardiovascular clinical trial: An APEX substudy

Competing risk methods are time‐to‐event analyses that account for fatal and/or nonfatal events that may potentially alter or prevent a subject from experiencing the primary endpoint. Competing risk methods may provide a more accurate and less biased estimate of the incidence of an outcome but are rarely applied in cardiology trials. APEX investigated the efficacy of extended‐duration betrixaban versus standard‐duration enoxaparin to prevent a composite of symptomatic deep‐vein thrombosis (proximal or distal), nonfatal pulmonary embolism, or venous thromboembolism (VTE)–related death in acute medically ill patients (n = 7513). The aim of the current analysis was to determine the efficacy of betrixaban vs standard‐duration enoxaparin accounting for non‐VTE–related deaths using the Fine and Gray method for competing risks. The proportion of non‐VTE–related death was similar in both the betrixaban (133, 3.6%) and enoxaparin (136, 3.7%) arms, P = .85. Both the traditional Kaplan‐Meier method and the Fine and Gray method accounting for non‐VTE–related death as a competing risk showed equal reduction of VTE events when comparing betrixaban to enoxaparin (HR/SHR = 0.65, 95% 0.42‐0.99, P = 0.046). Due to the similar proportion of non‐VTE–related deaths in both treatment arms and the use of a univariate model, the Fine and Gray method provided identical results to the traditional Cox model. Using the Fine and Gray method in addition to the traditional Cox proportional hazards method can indicate whether the presence of a competing risk, which is dependent of the outcome, altered the risk estimate.     

Matière à spéculer : les produits laitiers saisis par l’écrit

This article seeks to describe the work of dairy products speculators. It reveals the effort, cognitive and material, that enables these actors to handle the widening of their range of action, but also the contraction in the timescale of that action, two dynamics characteristic of the financialization process currently underway in certain international agricultural markets. In contrast with certain works critical of finance, which report a decoupling of the “financial sphere” from the “real economy”, it reveals – through close attention to the graphic media employed – agents who are aware of the materiality of the products they manipulate, despite their growing distanciation, both cognitive and geographical, from the target of their activity.     

Validation of the traumatic sexualization survey for use with heterosexual men

Two studies were conducted to validate the Traumatic Sexualization Survey (TSS) for use with heterosexual men. In Study 1, an online sample of men completed the TSS and measures used to examine convergent and divergent validity. An exploratory factor analysis revealed that the TSS had a similar factor structure in men as previously found in women. The TSS demonstrated adequate reliability and validity with men. In Study 2, male sexually transmitted disease clinic patients completed the TSS and a measure of child maltreatment. Men with a child sexual abuse (CSA) history reported higher levels of traumatic sexualization than men with a history of only physical abuse or no abuse, providing some preliminary evidence of construct validity. The TSS appears to be an adequate measure of maladaptive attitudes that have been conceptually linked to CSA impact in men.     

Rates of asymptomatic nonurethral gonorrhea and Chlamydia in a population of university men who have sex with men

Abstract Objectives: The study determined prevalence of asymptomatic nonurethral gonorrhea and chlamydia in men who have sex with men (MSM) seen at the Columbia University Health Service for routine care. Participants: The study enrolled 200 participants from March 2007 to May 2010. Results: Specimens were tested using culture and nucleic acid amplification testing (NAAT): 3.5% (n = 7) tested positive for pharyngeal gonorrhea by NAAT, none were positive by culture; 3% (n = 6) tested positive for rectal chlamydia by NAAT and 0.5% (n = 1) by culture. Conclusions: The incidence of pharyngeal gonorrhea and rectal chlamydia in MSM who visited the Columbia Health Service was similar to rates of asymptomatic nonurethral gonorrhea and chlamydia in studies conducted in the MSM population in non-university settings. This suggests that, following the Centers for Disease Control and Prevention guidelines, (1) 3-site testing for MSM seen at the Columbia clinic is indicated. NAAT is more sensitive than culture for nonurethral gonorrhea and chlamydia.     

Urbanization,Economic Structure,Political Regime,and Income Inequality

Social Indicators Research - The study examined the effect of urbanization on income inequality for 21 Sub Saharan African countries over the period 1984–2014 using heterogeneous panel...     

A Borda count for partially ordered ballots

The application of the theory of partially ordered sets to voting systems is an important development in the mathematical theory of elections. Many of the results in this area are on the comparative properties between traditional elections with linearly ordered ballots and those with partially ordered ballots. In this paper we present a scoring procedure, called the partial Borda count, that extends the classic Borda count to allow for arbitrary partially ordered preference rankings. We characterize the partial Borda count in the context of weighting procedures and in the context of social choice functions.