Abstract In this study, we examined the mechanics and energetics of locomotion with a paddle-wheel boat and a water bike. Power output ([Wdot]tot) was measured directly on the water bike by means of an instrumented chain-ring. The simultaneous assessment of oxygen uptake ([Vdot]O2) allowed the computation of the “overall” efficiency of locomotion (ηo = [Wdot]tot / [Vdot]O2). Mean ηo was 0.27 (s = 0.02), which was unaffected by the speed, and was assumed to be the same for the two boats as both are semi-recumbent bicycles. For the paddle-wheel boat, [Wdot]tot was then obtained from ηo and measures of [Vdot]O2. The power to overcome (passive) drag was calculated as [Wdot]d = D · v (where D is the force measured by means of a load cell when towing the boats at given speeds). Propelling efficiency was calculated as ηp = [Wdot]d / [Wdot]tot, which was lower with the paddle-wheel boat (mean 0.35, s = 0.01) than with the water bike (mean 0.57, s = 0.01). The observed differences in ηp and [Wdot]d explain why at the highest speed tested (~3 m · s?1), the energy required to cover a unit distance with the water bike is similar to that required to move the paddle-wheel boat at 1.3 m · s?1. 相似文献
This study examined the dispositions, experiences, and expectations of international students in a developing country to understand
the increasing phenomenon of reverse student flows and the role of the political economy in international student mobility.
Students’ dispositions, experiences and expectations—referred here collectively as “orientations”—served as the guiding framework
for this study. Data were drawn from survey responses from 279 international students at universities throughout Mexico and
analyzed to explore the orientations among students from Europe, Latin America and North America. Findings showed significant
differences among international students’ dispositions, experiences, and expectations by these geographical regions of origin.
In a broader context, this research addressed the important role of developing countries as not only senders but also receivers
of international students. This research also demonstrated the ways that the political economy shape the orientations of students
studying abroad. 相似文献
This paper proposes a model to assess the level of maturity in Virtual Communities of Practice (VCoPs). The model is based on a theoretical construction attained from the analysis of previous frameworks proposed in literature. Using this construction, we have proposed eight main organizational, managerial and technological levers to improve the performance of VCoPs. Additionally, the model presents the analysis of four performance metrics obtained from these VCoP management levers. The model presented can be used as a benchmarking tool for analysing how companies perform in their management of VCoPs. After developing the model, we applied it to a benchmarking study of four global oil and gas companies. Our results include a performance comparison among these companies as well as the main practices and technologies they use to achieve success in the management of VCoP. 相似文献
In this study, we assessed the longitudinal effects of social-cognitive mechanisms on the self-reported use of doping substances and supplements among Italian high school students. In total, 1232 students completed questionnaires measuring various psychological factors hypothesized to influence students' intention to use substances. Three months later, 762 of the students completed the same questionnaires a second time and also reported their use of substances during the time between assessments. Overall, the percentages of students using doping substances (2.1%) or supplements (14.4%) were consistent with values reported in the literature. Analysis of the data showed that adolescents' intention to use doping substances increased with stronger attitudes about doping, stronger beliefs that significant others would approve of their use, a stronger conviction that doping use can be justified, and a lowered capacity to resist situational pressure or personal desires. In turn, stronger intentions and moral disengagement contributed to a greater use of doping substances during the previous 3 months. Doping use was also correlated significantly to supplementation. In conclusion, our results provide novel information about some of the psychological processes possibly regulating adolescents' use of doping substances and supplements. The results also highlight possible areas for future study and intervention, focusing on the prevention of adolescents' substance use. 相似文献
This article investigates experimentally the effects of sensational content on viewing choices and satisfaction in television consumption. The authors found that the presence of verbal violence in one program causes subjects to watch more of that program. However, subjects do not experience higher satisfaction with the program. In addition, they report lower satisfaction with the overall viewing experience. These findings are robust to the use of different program types for the experimental manipulation. Overall, the results pose a challenge to the use of audience figures as a measure of enjoyment or satisfaction. 相似文献
Responses to a written beliefs test for 178 eighth grade students and interviews with a subset of the students are analysed to investigate students' beliefs about the tentativeness of scientific knowledge and about the autonomy and strategies appropriate for science learning. These three dimensions of beliefs are salient because they align with the image of science teaching promoted by current reform movements. Analyses focus on change in beliefs and relationships among dimensions of beliefs and between those beliefs and students' understandings of science concepts. Results show that students' beliefs do not change much during the one-semester course. Students who view scientific knowledge as tentative also try to understand science. Autonomous students do not hold the most productive learning strategies, though students with low autonomy develop significantly less coherent understandings of science concepts. Instructional implications focus on potential roles of teachers and technology in promoting productive beliefs about scientific knowledge and science learning. Implications for individualized instruction follow classroom-level implications. 相似文献
Purpose: The aim of the paper is to evaluate how advisory services stimulate the adoption of rural development policies (RDP) aiming at value creation.
Design/methodology/approach: By linking the use of agricultural extension services (AES) to policies for value creation, we will put forward an empirical analysis in Italy, with the aim of evaluating the capability of AES in bringing about higher access to rural policies for value creation in geographical indications (GI) contexts.
Findings: Results of our analyses evidence, on the one side, higher capability of funds attraction in GI areas. On the other side, path dependency schemes in accessing RDP are evident. Higher rates of access with the support of advisory services emerge, but only in traditional measure to fund farms’ investments. On the contrary, the use of AES does not facilitate access to other measures for value creation.
Practical implications: Our hypothesis is that AES include the support towards farm strategies of development through the adoption of RDP aiming at value creation in GI areas. Our analysis presents practical implications, in terms of a clear need for upgrading and broadening AES’ competencies in the field of projecting farm development and knowledge transfer in the field of funds to be obtained by RDP.
Theoretical implications: From a theoretical point of view, the paper may provide a contribution to theoretical debate by offering new insights into the role of advisory services in stimulating innovations and access to support policies.
Originality/value: This paper tries to fill a gap in the agricultural extension literature. We posit that the role of AES should comprehend a deeper knowledge (and knowledge transfer) concerning the opportunities provided by RDP. 相似文献