世界各国聚焦氢能源经济

氢是宇宙中最丰富的元素，地球上分布着大量的氢，其来源丰富。氧还是元素周期表中最轻的一个元素，与其他物质相比，具有较高的重量比能量。氢的燃烧产物是水，非常清洁，不会对环境造成污染。因此人们对氢能源的开发与利用也产生了极大的兴趣。     

Visual interactive simulation an aid to decision making

This paper describes a technique of visual interactive simulation. The technique allows a simulation model to be dynamically displayed on a visual display unit. The user can watch the model progress through time and has the ability to stop, interact and try alternative decision strategies. The paper shows that by watching a simulation model progress through time and having the ability to interact with it, a user can improve his analysis and understanding of the original problem situation.     

Positive Changes in Perceptions and Selections of Healthful Foods by College Students After a Short-Term Point-of-Selection Intervention at a Dining Hall

Abstract

Objective: Determine the effects of a short-term, multi-faceted, point-of-selection intervention on college students’ perceptions and selection of 10 targeted healthful foods in a university dining hall and changes in their self-reported overall eating behaviors. Participants: 104 college students, (age 18–23) completed pre-I and post-I surveys. Methods: Pre-survey collected at dining hall in April 2007, followed by 3-week intervention then post-survey collected via email. Healthy choice indicators, large signs, table tents, flyers and colorful photographs with “benefit-based messages” promoted targeted foods. Response rate to both surveys was 38%. Results: Significantly more participants reported that healthful choices were clearly identified in the dining hall after the intervention. Over 20% of participants reported becoming more aware of healthful food choices in the dining hall after the intervention. Significant increases in self-reported intake were reported for cottage cheese and low-fat salad dressing, with a trend toward increased consumption of fresh fruit. Seven of the 14 assessed eating behaviors had significant changes in the desired direction. Increased awareness of healthful foods was the top reason for self-reported changes in overall eating behaviors. Conclusion: Short-term, multi-faceted, point-of-selection marketing of healthful foods in university dining halls may be beneficial for improving college students’ perceptions and selections of targeted healthful foods in the dining hall and may improve overall eating behaviors of college students.     

The Status of Nutrition Education in ACHA College and University Health Centers

Abstract

An assessment of the prevalence and scope of nutrition services offered through 208 randomly selected American College Health Association member student health centers revealed that 79% of the 160 respondents provided some type of nutrition education for students. One-to-one counseling, available at 96% of the institutions, was the most common approach. The larger the school's enrollment, the more likely it was to provide programs in nutrition. All of the institutions with student populations of more than 35,000 offered some type of nutrition service, as did 52% of the 19 schools with enrollments between 2,000 and 5,000. Health educators, nurses, doctors, dietitians, and trained peer educators provided the services, with registered dietitians the most common providers and often coordinators of the programs. Costs to students for nutrition interventions were nominal; weightmanagement programs were the most expensive and showed the greatest variation in content.     

Physical Activity,Exercise, and Sedentary Behavior in College Students

Abstract

Objective: This article examines students’ perceptions of individual and institutional responsibility for sexual health so that institutions can better provide for the needs of their students to increase academic success and healthy relationship outcomes. Participants: Students from 2- and 4-year colleges in 1 state (N = 78). Methods: From May through November 2010, the authors used go-along interviews to examine students’ perceptions of resources for sexual health on their campuses. Results: Participants believed that it is the college's responsibility to provide resources and the responsibility of students to access resources. Participants at 2-year schools wanted referrals to resources, whereas participants at 4-year schools expected resources to be available and emphasized the importance of a supportive community. Conclusions: Students at 2- and 4-year colleges have different expectations of their institutions; by making resources and referrals for sexual health available, colleges can better serve their students, which will result in improved health outcomes.     

A Model for Implementing an Evidence-Based Practice in Student Fieldwork Placements: Barriers and Facilitators to the Use of “SBIRT”

ABSTRACT

This article reports on focus group data analysis that was used to understand initial, largely positive outcomes from a university-based initiative to disseminate and implement an evidence-based practice (EBP)—Screening, Brief Intervention, and Referral to Treatment for Substance Use (SBIRT)—into student fieldwork placements, which are usual care social work settings. Focus groups were conducted with three groups of stakeholders involved in the ongoing project: social work department faculty (n = 10), bachelor- and master-level social work students (n = 8), and social work fieldwork instructors (n = 6). Dimensional analysis of the focus group data yielded results indicating that dissemination and implementation of SBIRT was influenced by agency- and school-level factors and perceived fit between the EBP and individual professional identity, intrapersonal characteristics, and timing. The resulting model, developed through the focus group analysis, is offered and shows how these factors interacted and affected training, supervision, and use of the EBP. The model provides social work educational programs and agencies a working tool for diagnosing and proactively addressing barriers and breakdowns in the EBP implementation process. Future research that tests the model as a diagnostic tool and generates knowledge about its influence in developing competent evidence-based practitioners is indicated. Future focus groups in relation to this initiative are needed to better understand these barriers and facilitators in the EBP implementation process and their critical roles in the process of translating SBIRT into standard social work practice.     

A Convolution Estimator for the Density of Nonlinear Regression Observations

Abstract. The problem of estimating an unknown density function has been widely studied. In this article, we present a convolution estimator for the density of the responses in a nonlinear heterogenous regression model. The rate of convergence for the mean square error of the convolution estimator is of order n ^?1 under certain regularity conditions. This is faster than the rate for the kernel density method. We derive explicit expressions for the asymptotic variance and the bias of the new estimator, and further a data‐driven bandwidth selector is proposed. We conduct simulation experiments to check the finite sample properties, and the convolution estimator performs substantially better than the kernel density estimator for well‐behaved noise densities.