Longitudinal resistance performance of granular ballast beds under cyclic symmetric displacement loading

The longitudinal resistance performance of a granular ballast bed under cyclic symmetric displacement loading was studied based on a full-scale test model of ballast track structures. The change law of the longitudinal resistance characteristics of the ballast bed under variable displacement amplitudes was analyzed. The results show that: the resistance-displacement curves of a granular ballast bed are a set of closed hysteretic curves, indicating obvious energy consumption; a granular ballast bed softens gradually during the cyclic process with constant displacement amplitude, and the residual deformation rate increases nonlinearly with increasing cycle number; the peak value of the longitudinal resistance of lines decreases with increasing cycle number; the cyclic softening of a granular ballast bed is dependent on the displacement amplitude–the higher the displacement, the more severe the cyclic softening will become; after cyclic displacement loading is applied several times, the longitudinal resistance of the bed will degenerate obviously, and the higher the displacement amplitude, the higher the longitudinal resistance attenuation rate of the ballast bed will become.     

Different ways in which students handle chance encounters in the explorative setting of a dice game

The purpose of this study is to investigate the ways in which Swedish seventh grade students (12 and 13 years old) handle chance encounters. Four groups of students working in pairs participated in the study. In the group discussions, which were tape-recorded and fully transcribed, the students were encouraged to explore strategies for winning a specifically designed dice game based on the sum of two dice. The dice game included four different set-ups of dice designed to bring to the fore different aspects of probability modelling and to offer the student the opportunity to encounter small differences in the mathematical structure of the sample space and of the probability distribution between the four different set-ups. The study describes strategies that the students use when confronted with these different set-ups, what their activities imply in terms of resources in handling random phenomena and what the dice game offers in terms of opportunities for learning probability. In order to explain such meaning-making processes the students’ activities are viewed from a perspective that takes into consideration how the students’ understanding varies with their interpretations of the situation they are confronted with, i.e., how they contextualize the different set-ups of the dice game. The results show how the students, during the course of the game, reorganize their interpretations of the mathematical content confronting them, and how a variation of guiding principles becomes the object of exploration. Approaches of extremes and a number model are described as a means for the students to identify and assign probabilities for the total of two dice.     

Design,development, and implementation of electronic learning environments for collaborative learning

Developments in society and business, and related changes in higher education and lifelong learning, require educators and educational designers or technologists to rethink education. Examples of such changes are the growing importance of achieving complex learning, the integration of learning and work in education, and the need for improved flexibility with regard to time, place, and individual needs. These changes cannot simply be responded to by adding technological solutions implemented according to existing educational approaches. Instead, an integrated view of e-learning is necessary, characterized by the combination of pedagogical, technical, social, and organizational factors. This two-part special issue elaborates on the different characteristics of integrated e-learning, from design through future topics for research. He would like to give special thanks to Jan Elen and Brent Wilson, who took on the task of reviewing and discussing all of the contributions, both at AECT 2003 in Anaheim and for this issue, and J. Michael Spector, Development Editor of this journal, for his faith in all of us.     

Moderators of the interest congruence-occupational outcome relation

Several reasons for the modest relation between interest congruence and occupational outcomes are discussed, but focus is placed on possible moderators of this relation. Specifically individual differences, environmental differences and time are proposed as potential moderators. Overall, it is important to investigate theoretically driven moderators of the congruence-outcome relation to further our knowledge of this area.     

A Systematic Literature Review of Funding for Higher Education Institutions in Developed Countries

Resource allocation and funding in higher education is crucial to the success of reform and transformation of our higher education system. With a view to identifying trends and best practices in the area, utilizing a method of systematic literature review, we have critically reviewed relevant theories and practices from developed counties that are covered in the scholarly literature published in English in the past 10 years. Our review has revealed: (1) Several universal trends have exerted a decisive impact on resource allocation in higher education, for example, funding reduction and tuition fee increases, performancebased funding, privatization, corporatization, and internationalization; (2) Several theories underpin key research in the area, for example, new institutional economics, resource dependence theory, and political economy; (3) Several controversial issues have made their way into public debate, for example, higher education as a public good or private good, academic capitalism, educational equity, and the role of econometrics.     

Influence of low protein diets on gene expression of digestive enzymes and hormone secretion in the gastrointestinal tract of young weaned piglets

To investigate dietary protein level effects on digestive mechanisms, weaned piglets were fed for 45 d with diets containing 20%, 17%, or 14% crude protein (CP) supplemented to meet requirements for essential amino acids. This article describes the influence of dietary protein on gastrointestinal hormones and expression of an array of digestive enzymes in the gastrointestinal tract and pancreas. Results indicated that there were no significant differences in expression of enzymes involved in carbohydrate digestion, except for maltase in the duodenum. In the jejunum, amylase expression in pigs fed 20% CP was much higher than that in pigs fed other diets (P<0.05) and maltase expression in those fed 17% CP was higher than that in other treatments (P<0.05). Although there were no remarkable differences in expression of aminopeptidase in the small intestine or carboxypeptidase in the pancreas (P>0.05), there was a trend towards higher expression of various proteases in pigs fed 17% CP. The duodenal expression of enteropeptidase in diets with 14% and 17% CP was significantly higher than that with 20% CP (P<0.05), but treatment differences did not existed in jejunum (P>0.05). The expression of GPR93 as a nutrient-responsive G protein-coupled receptor in 14% and 17% CP diets was significantly higher than that in 20% CP diet in the small intestine (P<0.05). The expressions of genes for pancreatic enzymes, lipase and elastase, were significantly higher in pigs fed diets with low CP, while similar trends occurred for carboxypeptidase, chymotrypsin and amylase. Conversely, the gastric expressions of pepsinogen A and progastricsin were lower with the 17% CP diet. Differences between treatments were found in the gastric antral contents of cholecystokinin and somatostatin: both increased in pigs fed 17% CP, accompanied by decreased content of motilin, which was also seen in plasma concentrations. These patterns were not reflected in duodenal contents. In general, 17% dietary CP was beneficial to the digestion of nutrient substance in the gastrointestinal tract.     

The Experience of Columbian Child Soldiers from a Resilience Perspective

There are child soldiers fighting with government forces and opposition groups in more than 30 countries worldwide. Although studies have been conducted on the impact of war-related trauma on children, very few have focused on those children who do not exhibit trauma-related symptoms after experiencing armed combat. The purpose of this study was to identify and understand some of the mechanisms and resources that resilient children draw upon to overcome the trauma of child soldiering. Six Colombian child soldiers were recruited through purposive sampling techniques to participate in a narrative study focusing on their lived experiences and their personal understanding of how they were able to overcome the effects of war trauma. Six narrative themes were identified and discussed in terms of the literature on trauma and childhood resilience and also related to counselling needs and services.     

Hydrogen sulfide from a NaHS source attenuates dextran sulfate sodium (DSS)-induced inflammation via inhibiting nuclear factor-κB

This study investigated the alleviating effects of hydrogen sulfide (H₂S), derived from sodium hydrosulfide (NaHS), on inflammation induced by dextran sulfate sodium (DSS) in both in vivo and in vitro models. We found that NaHS injection markedly decreased rectal bleeding, diarrhea, and histological injury in DSS-challenged mice. NaHS (20 µmol/L) reversed DSS-induced inhibition in cell viability in Caco-2 cells and alleviated pro-inflammation cytokine expression in vivo and in vitro, indicating an anti-inflammatory function for H₂S. It was also found that H₂S may regulate cytokine expression by inhibiting the nuclear factor-κB (NF-κB) signaling pathway. In conclusion, our results demonstrated that H₂S alleviated DSS-induced inflammation in vivo and in vitro and that the signal mechanism might be associated with the NF-κB signaling pathway.