Finitary quasivarieties are characterized categorically by the existence of colimits and of an abstractly finite, regularly projective regular generator G. Analogously, infinitary quasivarieties are characterized: one drops the assumption that G be abstractly finite. For (finitary) varieties the characterization is similar: the regular generator is assumed to be exactly projective, i.e., hom(G, –) is an exact functor. These results sharpen the classical characterization theorems of Lawvere, Isbell and other authors.Supported by the Czech Grant Agency (Project 201/02/0148).Special issue of Studia Logica: Algebraic Theory of Quasivarieties Presented byM. E. Adams, K. V. Adaricheva, W. Dziobiak, and A. V. Kravchenko相似文献
As a result of studies examining factors involved in the learning process, various structural models have been developed to explain the direct and indirect effects that occur between the variables in these models. The objective was to evaluate a structural model of cognitive and motivational variables predicting academic achievement, including general intelligence, academic self-concept, goal orientations, effort and learning strategies. The sample comprised of 341 Spanish students in the first year of compulsory secondary education. Different tests and questionnaires were used to evaluate each variable, and Structural Equation Modelling (SEM) was applied to contrast the relationships of the initial model. The model proposed had a satisfactory fit, and all the hypothesised relationships were significant. General intelligence was the variable most able to explain academic achievement. Also important was the direct influence of academic self-concept on achievement, goal orientations and effort, as well as the mediating ability of effort and learning strategies between academic goals and final achievement. 相似文献
Visual distortions of perceived lengths, angles, or forms, are generally known as “geometric–optical illusions” (goi). In the present paper we focus on a class of gois where the distortion of a straight line segment (the “target” stimulus) is induced by an array of non-intersecting curvilinear elements (“context” stimulus). Assuming local target–context interactions in a vector field representation of the context, we propose to model the perceptual distortion of the target as the solution to a minimization problem in the calculus of variations. We discuss properties of the solutions and reproduction of the respective form of the perceptual distortion for several types of contexts. Moreover, we draw a connection between the interactionist model of gois and Riemannian geometry: the context stimulus is understood as perturbing the geometry of the visual field from which the illusory distortion naturally arises. The approach is illustrated by data from a psychophysical experiment with nine subjects and six different contexts. 相似文献
The study compared clinical, psychopathological, and personality profiles between immigrants and Spanish native-born pathological gambling patients. A total of 1,601 native-born and 133 immigrant patients attending treatment at a specialized hospital unit were administered a battery of questionnaires during clinical assessment. Outcome measures were compared between both groups and the incremental predictive accuracy of the area of origin was examined using a regression model. Native-born Spaniards showed a mean 2.6 yr. greater duration of the disorder, while immigrants scored higher on South Oaks Gambling Screen, frequency of going to casinos, and total money spent (in a single day and/or to recover losses). General psychopathology and personality scores did not differ between the cohorts. However, immigration from Asia had a statistically significantly incremental validity for pathological gambling in South Oaks Gambling Screen scores. Both cohorts shared more similarities than differences in their gambling profiles. 相似文献
Household structure for older people’s subjective well-being is important to promote healthy ageing in the context of the rapid increase of the older population. Living with adult children is known to promote older people’s life satisfaction, a key indicator of subjective well-being, whereas others claim a negative impact of such intergenerational coresidence. This study aims to empirically test these theories (family support vs. family conflict), by examining the role of homeownership–another important factor contributing to subjective well-being–in this association between intergenerational coresidence and life satisfaction. Analysing the nationally representative data on the elderly population in South Korea, the findings showed that intergenerational coresidence decreases life satisfaction when the elderly achieve a certain level of housing security by living in owner-occupied housing. Living with adult children is negatively associated with life satisfaction particularly for older old homeowners compared to younger old owners. Our findings provide implications for public policies promoting intergenerational coresidence and asset-based welfare to enhance older people’s well-being in Korea and more broadly in East Asia.
Personality is hypothesized to have direct and indirect effects on health-related quality of life (HRQoL) through the mediating role of perceived occupational stressors. This hypothesized model was tested with Chinese judges, individuals characterized by high occupational stress. In this cross-sectional study, 330 judges undergoing professional training at the Shandong Judge Training Institute completed questionnaires assessing their personality (Big Five Inventory, BFI), perceived occupational stressors (Occupational Role Questionnaire, ORQ), and HRQoL (Medical Outcomes Study Short-Form Health Survey, SF-36). The proposed model was tested using structural equation modelling (SEM) approaches. The SEM analysis showed a good fit of the data to the hypothesized model(x2/df = 1.52, P?0.001, RMSEA = 0.04, GFI = 0.87, CFI = 0.91, TLI = 0.89). The model explained 60 % of the variance in HRQoL. A strong negative direct effect of neuroticism on HRQoL (?0.50, P?0.01) was observed. Neuroticism also had a negative indirect effect (?0.18, P?0.01) on HRQoL by positively influencing (β?=?0.47, P?0.01) perceived occupational stressors which had significantly negative direct effects (β?=??0.39, P?0.01) on HRQoL. However, both the direct effects of openness, conscientiousness, agreeableness and extraversion on HRQoL and their indirect effects mediated by perceived occupational stressor were not significant. In conclusion, our hypotheses were partly supported by the data. We found that neuroticism had both direct effect on HRQoL and an indirect effect through the mediating role of perceived occupational stressors which also had a significant effect on HRQoL, whereas neither the direct nor the indirect effects of openness, conscientiousness, agreeableness and extraversion on HRQoL of Chinese judges had been found in current study. 相似文献
The aim of this article is to report the prevalence of youth victimization and poly-victimization in northern Chile. Using the Juvenile Victimization Questionnaire, a sample of 706 adolescents ages 12 to 17 were surveyed. The results indicated that 89% of the participants had experienced victimization at least once in their lives and 76.8% had experienced at least 1 experience of victimization in the past year. The most frequent forms were conventional crimes (70% and 54.7%), witnessing and indirect victimization (63.2% and 45.2%), and peer and sibling victimization (50.0% and 34.6%), for the lifetime and the past year, respectively. Sexual victimization was less common for both time periods, but still relevant (15.9% lifetime and 9.9% past year). Older females and younger adolescents presented a higher risk of victimization particularly in conventional crimes and victimization by caregivers. As for poly-victimization, 21% of the adolescents presented between 4 and 6 different forms of victimization (the low poly-victimization group) and 16% reported seven or more (the high poly-victimization group) in the last year. The results showed that child and adolescent victimization is a significant problem in Chile. Percentages of victimization in Chilean adolescents were higher than those found in Europe or North America. Results from the group of poly-victims reinforces the need to evaluate the multiple forms of victimization that affect adolescents in Chile and to prioritize it in the design of the treatment of the consequences of violence, taking into account differences in gender and age. 相似文献
The authors' aim was to find the features of balance, proprioception, and gross motor development of Chinese children 3–6 years old and their correlations, provide theoretical support for promoting children's motor development, and enrich the world theoretical system of motor development. This study used a Tekscan foot pressure measurement instrument (Tekscan, Inc., Boston, MA), walking on a balance beam, Xsens 3-dimensional positional measuring system (Xsens Technologies, Enschede, the Netherlands), and Test of Gross Motor Development-2 to assess static balance, dynamic balance, knee proprioception, and levels of gross motor development (GMD) of 3- to 6-year-old children (n = 60) in Beijing. The results are as follows: children had significant age differences in static balance, dynamic balance, proprioception, and levels of GMD; children had significant gender differences in static balance, proprioception, and levels of GMD; children's static balance, dynamic balance, and proprioception had a very significant positive correlation with GMD (p < .01), but no significant correlation with body mass index. 相似文献
The purpose of this study was to compare African American and non-African American hepatitis C virus (HCV) patients on self-reported symptoms of HCV liver disease and psychosocial characteristics commonly affected by it in a sample of 309 patients enrolled in a randomized controlled trial. African Americans (n = 196) rated a higher reliance on religion/spirituality for coping with HCV compared to non-African Americans. This study’s findings are a basis for encouragement of public health efforts and programs to seek partnerships with African American faith and religious communities to identify and treat undiagnosed cases of HCV and promote HCV awareness. 相似文献