Bicartesian Coherence

Coherence is demonstrated for categories with binary products and sums, but without the terminal and the initial object, and without distribution. This coherence amounts to the existence of a faithful functor from a free category with binary products and sums to the category of relations on finite ordinals. This result is obtained with the help of proof-theoretic normalizing techniques. When the terminal object is present, coherence may still be proved if of binary sums we keep just their bifunctorial properties. It is found that with the simplest understanding of coherence this is the best one can hope for in bicartesian categories. The coherence for categories with binary products and sums provides an easy decision procedure for equality of arrows. It is also used to demonstrate that the categories in question are maximal, in the sense that in any such category that is not a preorder all the equations between arrows involving only binary products and sums are the same. This shows that the usual notion of equivalence of proofs in nondistributive conjunctive-disjunctive logic is optimally defined: further assumptions would make this notion collapse into triviality.     

Discrimination of the Second Generation: Evidence from a Field Experiment in Norway

A major question in labour market research is the extent to which discrimination in employments causes the disadvantages experienced by children of immigrants. This article contributes to the debate by utilising a correspondence test study in which pairs of equivalent résumés and cover letters—one with a Pakistani name and one with a Norwegian name—were sent in response to 900 job openings in the greater Oslo area. The results show that applicants with Norwegian names on average are 25 % more likely to receive a call back for a job interview than equally qualified applicants with Pakistani names. More refined analyses demonstrate that the effect of ethnic background on employment probabilities is larger among men than women and larger in the private sector than in the public sector, and important variations among the occupations included in the study are revealed. In an effort to separate the potentially conflating effects of gender and sector, all applications to gender-segregated occupations were removed from the analyses. Interestingly, the gender differences disappear when exclusively analysing discrimination in gender-integrated occupations by sector. In gender-integrated occupations in the private sector, the gender difference in fact is reversed, indicating that women with minority background are treated less favourably than are minority men in the private sector. These results suggest that the intersection of gender, ethnicity, and sector should be scrutinised more carefully in future field experiments.     

Models for normal intuitionistic modal logics

Kripke-style models with two accessibility relations, one intuitionistic and the other modal, are given for analogues of the modal systemK based on Heyting's prepositional logic. It is shown that these two relations can combine with each other in various ways. Soundness and completeness are proved for systems with only the necessity operator, or only the possibility operator, or both. Embeddings in modal systems with several modal operators, based on classical propositional logic, are also considered. This paper lays the ground for an investigation of intuitionistic analogues of systems stronger thanK. A brief survey is given of the existing literature on intuitionistic modal logic.     

参照性交流双方学习效果和选择性注意的比较*

以144名大学生为被试,采用参照性交流范式,设计复杂性不同的材料,创设功能预测和维度选择任务,探查比较参照性交流双方学习效果与选择性注意特点。结果高成绩组block10成绩显著高于低成绩组,关系复杂性主效应显著,参照性交流双方维度选择结果不存在显著差异,关系复杂性影响维度选择的整体结果、有关维度选择结果。表明：双方学习效果不平衡,但选择性注意协调一致,均不受复杂性影响。     

Chemosignalling effects of human tears revisited: Does exposure to female tears decrease males’ perception of female sexual attractiveness?

Gelstein et al. reported the results of three experiments suggesting a dampening influence of inhalation of female emotional tears on males’ arousal and perception of female sexual attractiveness, specifically in non-sexual situations. This prompted the hypothesis that crying exerts its influence on others not only via the auditory and visual mode but also via chemosignals. In three studies, we attempted to replicate and extend Gelstein et al.’s findings by including an additional condition with irritant tears, by using pictures of sexually attractive women, and by testing related hypotheses on the pro-social effects of exposure to tears. All three studies, separately or combined in a meta-analysis, failed to replicate the original inhibitory effects of tears. In addition, sniffing tears did not affect measures of connectedness, aggression and pro-social behaviour. It is concluded that the effects of female tears on male arousal and perception of female sexual attractiveness, if any, are very weak at best. Rather, it seems that crying exerts its strong inter-personal effects through the visual and auditory sensory channels.     

Parallel sexual relationships in the Norwegian context

The purpose of the paper is to describe and analyse the prevalence of parallel sexual relationships among adult Norwegians in terms of social background variables, possibility factors and motivational factors. Data stem from two cross-sectional, postal questionnaire surveys in 1987 and 1992 on two separate representative samples of 10,000 Norwegians aged between 18 and 60. The results showed that 16% of the respondents reported one or more parallel sexual relationships. The prevalence of parallel sexual relationships increased with possibility factors, such as the number of travelling days and population density. Among motivational factors, parallel sexual relationships increased with the number of years married/cohabiting, except for those married the longest. It decreased with increasing age of first intercourse, and increased with the number of partners before the last partnership. Of those not satisfied with coital frequency with their permanent partner, 22% had parallel sexual relationship experience compared to 12% among those who were satisfied. Furthermore, more men than women reported parallel sexual relationships; respondents with higher levels of education more often reported parallel sexual activity than those with lower level of education; and subjects born between 1937 and 1956 reported more parallel sexual activity than the other cohorts. When controlled for the number of years married/cohabiting, the predicted trend suggests that for the cohorts born up to 1970, men and women with lower and higher levels of education have become more similar as regards parallel sexual behaviour. © 1998 John Wiley & Sons, Ltd.     

Impacts of school-wide positive behaviour support: Results from National Longitudinal Register Data

Problem behaviour in schools may have detrimental effects both on students' well-being and academic achievement. A large literature has consistently found that school-wide positive behaviour support (SWPBS) successfully addresses social and behavioural problems. In this paper, we used population-wide longitudinal register data for all Norwegian primary schools and a difference-in-difference (DiD) design to evaluate effects of SWPBS on a number of primary and secondary outcomes, including indicators of externalising behaviour, school well-being, pull-out instruction, and academic achievement. Indications of reduced classroom noise were found. No other effects were detected. Analyses revealed important differences in outcomes between the intervention and control schools, independent of the implementation of SWPBS, and that a credible design like DiD is essential to handle such school differences.     

Body evaluation and coital onset: a population-based longitudinal study

This study examined the temporal relationship between body evaluation and coital onset. In a population-based longitudinal study, 1449 Norwegian girls and boys between 12 and 15 years of age were followed at 4 waves over a span of 13 years. Body evaluation was used in order to predict coital onset besides romantic appeal and psychological problems. For girls early in adolescence, body evaluation did not influence the probability of coital onset during the first 2-year period. In the subsequent 5-year period, body dissatisfaction increased the probability for coital onset when romantic appeal was held constant. Body evaluation did not influence the odds of coital onset among boys. The findings imply that the pattern of association between body evaluation and coital onset differs according to the timing of coital onset for girls. Future research needs to distinguish body image from romantic appeal in relation to first time sexual experiences.     

Duality between modal algebras and neighbourhood frames

This paper presents duality results between categories of neighbourhood frames for modal logic and categories of modal algebras (i.e. Boolean algebras with an additional unary operation). These results extend results of Goldblatt and Thomason about categories of relational frames for modal logic.