The maximum cardinality cut problem in co-bipartite chain graphs

A co-bipartite chain graph is a co-bipartite graph in which the neighborhoods of the vertices in each clique can be linearly ordered with respect to inclusion. It is known that the maximum cardinality cut problem (\({\textsc {MaxCut}}\)) is \({\textsc {NP}}{\text {-hard}}\) in co-bipartite graphs (Bodlaender and Jansen, Nordic J Comput 7(2000):14–31, 2000). We consider \({\textsc {MaxCut}}\) in co-bipartite chain graphs. We first consider the twin-free case and present an explicit solution. We then show that \({\textsc {MaxCut}}\) is polynomial time solvable in this graph class.     

Reactions to cyberbullying among high school and university students

In this study, behavioral and emotional reactions to cyberbullying were investigated by surveying 567 undergraduate-level university students and 211 high school students. Among the study participants, 170 of the undergraduates (29.98%) and 120 of the high school students (56.87%) reported that they had recently been cyberbullied. A four-factor scale with 37 items was used to investigate the behavioral cyberbullying reactions of victimized students. The four factors were revenge, countermeasure, negotiation and avoidance. An additional two-factor scale with 11 items was used to classify victimized students’ emotional reactions as either internalizing or externalizing. Explained variance values of both scales were above 50%, and the factors were found to have acceptable internal consistency coefficients. Behavioral and emotional reactions varied according to gender and school level. Computer self-efficacy and internet use were associated with different reaction types.     

The Characteristics of Child Sexual Abuse in the School Environment in Turkey

School may represent a protective factor, boosting the mental health of the student body, while also representing a risk factor that heightens the potential for mental health problems. The present study aims to identify the individual and familial characteristics associated with the incidents of child sexual abuse (CSA) in Turkey’s school environment. The incidents involving school-related CSA constituted 5.6% (N = 125) of 2,238 cases. The following was discovered: an adult committed the majority (64%) of CSA in the school environment; most adult perpetrators were teachers (62.5%). This study determined that the perpetrators manipulated the victims via methods that included physical abuse (11.2%), threats (19.2%), tricks/deception (15.2%), and taking photographs/videos with sexual content (3.2%); and CSA incidents involved intercourse (15.2%); and almost three-quarter of the victims of CSA in the school environment reported the incident late. This study indicates that peer perpetrators abuse younger victims and a greater proportion of male victims relative to adult perpetrators. In light of these findings, school security must be improved, especially in public schools, and trainings aimed at preventing bullying and sexual abuse (SA) should be given to all school staff, students, and parents.     

Ties in one block comparison experiments: a generalization of the Mallows–Bradley–Terry ranking model

This study is concerned with the extension of the Mallows–Bradley–Terry ranking model for one block comparison consisting of all the items of interest to situations which allow an expression of no preference. We consider a modification of the Mallows–Bradley–Terry ranking model by introducing an additional parameter, called an index of discrimination, in the model. This permits ties in the model. The maximum likelihood estimates of the parameters are found using a Maximization–Minimization algorithm: the evaluation of the mathematical expectations involved in the log-likelihood equation is obtained by generating samples of Monte Carlo Markov chain from the stationary distribution. In addition, a simulation study for asymptotic properties assessment has been made. The proposed method is applied to analyze data election.     

An alternative method correcting BDR type of heteroskedasticity by the weighting re-estimated absolute residuals

The aim of this paper is to introduce a new method which corrects residual variances for the butterfly distributed residuals (BDR). Distribution theory, confidence intervals, and tests of hypotheses are valid and meaningful only if the standard regression assumptions are satisfied. Heteroskedasticity is one of the violations of these assumptions and BDR is another type of heteroskedasticity. This study reveals an alternative approach to correct the BDR type of heteroskedasticity by the weighting re-estimated absolute residuals (WRAR). After giving brief information about heteroskedasticity and BDR type of heteroskedasticity, WRAR is introduced. WRAR and the usual variance stabilizing techniques are compared on multiple and simple regression models.     

Exploring Perceived Discrimination Among LGBT Individuals in Turkey in Education,Employment, and Health Care: Results of an Online Survey

This article explores the discrimination practices encountered by lesbian, gay, bisexual, and transgender (LGBT) individuals in education, income, employment, and health care in Turkey. Limited quantitative data on LGBT individuals are available in Turkey. This study collected data from 2,875 LGBT individuals through a Web-based survey. The findings suggest that LGBT individuals report perceived direct and indirect discrimination in accessing education, employment, and health care. In a country where LGBT rights are not yet recognized and antidiscrimination legislation covering sexual orientation and gender identity is still nonexistent, findings demonstrate perceived discrimination of LGBTs rarely turns into a legal complaint. Even when they do, most LGBTs in our sample report that they did not feel that the justice system addressed their grievances.     

Ties,sites and irregularities: pitfalls and benefits in using respondent-driven sampling for surveying a homeless population

Respondent-driven sampling (RDS) is a survey method for hidden populations and, as such, it offers a suitable approach for sampling the homeless. Surprisingly, the practical use of RDS in surveying homeless populations has only sporadically been described in the professional literature so far, and the specifics of using RDS for sampling this group have not been reflected in depth. The goal of the article is to investigate how three specific concerns, namely the transitional character of social ties among the homeless, problems with locating the interview site, and the irregular use of coupons, affect the sampling process. The findings of the article are based on experience using RDS for creating two independent samples of homeless persons in two Czech cities. Worries of poor referral effectiveness were disproved, but poor validity of the network size indicator, tendency towards irregular use of coupons, and negative effects arising from selecting service centres for the homeless as survey sites were confirmed.     

Mesurer les coǔts de licenciement: de l'intérět des méthodes directes

Les coǔts de licenciement, ainsi que l'appareil législatif et réglementaire régissant les relations professionnelles, sont souvent blǎmés pour les mauvaises performances du marché du travail. Toutefois, les études théoriques et économétriques sur l'impact économique de ces coǔts ne sont pas concluantes. Par le passé, on s'est surtout intéressé aux hypothèses fonctionnelles et à l'incidence des divers paramètres, mais on a très peu analysé la qualité et la précision des méthodes de mesure de ces coǔts, dont dépendent pourtant la plupart des résultats en cette matière. L'auteur examine les méthodes de mesure directes et indirectes couramment utilisées en ce domaine, et soutient qu'il est essentiel d'employer les méthodes quantitatives directes, rarement utilisées par les chercheurs, pour compléter les méthodes de mesure indirectes auxquelles on a généralement recours. Ce point est illustré par les résultats d'un sondage expérimental récemment mené en Australie.     

Appropriation et régulation des innovations biotechnologiques : pour une comparaison transatlantique

This article analyzes two biotechnological innovations — the tests of tracking the genetic risks of diseases and the transgenic organisms — and explores the controversies concerning the status of these new knowledges and the ways there are applied. It shows how these innovations were received in a different way in the United States and in France. The market regulation, which is strong in the USA is problematic in France. It is marginalized by the professional regulation in the case of the genetic tests. And in the other case it is limited by the control of the state, which constitutes some resources for the mobilization of the civil society against transgenic organisms. Finally the comparison consolidates the hypothesis of the emergence of a new regime of production of the knowledge, specified by the tension between a “market” regulation and a “consumerist-civic” regulation.