Do Principals Affect Student Outcomes: An Organizational Perspective

This research study investigated the principal's role as instructional manager, its relationship to student achievement, and how principals influence teachers to accomplish the school's goal of increasing student learning. Conceptually, principal instructional management includes those processes, both mental and physical, that the principal uses which result in other people executing formal and informal duties to achieve organizational goals. It deals mainly with planning, organizing and controlling teacher behavior to achieve organizational goals, but also includes monitoring and controlling resources. Subjects for the study included elementary school (K‐8) principals and teachers in 27 schools. Student achievement gain was determined by regression analysis where current achievement was regressed on prior achievement and SES for two years of data. Principal instructional management behavior was measured by a modified form of the Instructional Management Rating Scales, or IMRS (Hallinger, 1983). The results from the study question whether principals should be led by researchers and policymakers into thinking that increasing their instructional management behaviors will turn ineffective schools into effective ones. School improvement is a complex process that involves a host of factors which principals can influence, but not control. While principals play an important role as part of the schools' efforts in school improvement, the role of the principal in school improvement, must be placed in its proper perspective.     

Acute impact of submaximal resistance exercise on immunological and hormonal parameters in young men

In this study, we examined the acute effects of submaximal resistance exercise on immunological and hormonal parameters in 7 resistance-trained and 10 non-resistance-trained males. The participants, who were aged 29.5 +/- 7.1 years (mean +/- s), performed submaximal resistance exercise at 75% of their one-repetition maximum. Blood samples were taken before, during, immediately after, and 30, 60 and 120 min after exercise and analysed for leukocyte subpopulations and stress hormones. Total leukocytes, neutrophils and monocytes increased during exercise, reaching their maximum 2 h after exercise. Lymphocytes increased during exercise, T-helper cells returned to resting values after exercise, and natural killer cells and T-suppressor cells decreased below resting values. The CD4/CD8 ratio decreased during exercise but increased during recovery. The resistance-trained participants tended to have lower T-helper cell counts before, during and immediately after exercise and a lower CD4/CD8 ratio during recovery than the non-resistance-trained participants. Plasma cortisol correlated positively with leukocytes during exercise (r = 0.572, P < 0.05), but negatively with T-helper cells 30 and 60 min after exercise (r = -0.573, P < 0.05; r = -0.642, P < 0.01, respectively). Our results indicate that resistance exercise leads to acute changes in leukocyte counts, despite moderate hormonal changes, independent of training status. Regular resistance exercise might lead to decreased T-helper cell counts and a lower CD4/CD8 ratio, which could increase susceptibility to infections.     

The effects of skin and core tissue cooling on oxygenation of the vastus lateralis muscle during walking and running

Skin and core tissue cooling modulates skeletal muscle oxygenation at rest. Whether tissue cooling also influences the skeletal muscle deoxygenation response during exercise is unclear. We evaluated the effects of skin and core tissue cooling on skeletal muscle blood volume and deoxygenation during sustained walking and running. Eleven male participants walked or ran six times on a treadmill for 60 min in ambient temperatures of 22°C (Neutral), 0°C for skin cooling (Cold 1), and at 0°C following a core and skin cooling protocol (Cold 2). Difference between oxy/deoxygenated haemoglobin ([diffHb]: deoxygenation index) and total haemoglobin content ([tHb]: total blood volume) in the vastus lateralis (VL) muscle was measured continuously. During walking, lower [tHb] was observed at 1 min in Cold 1 and Cold 2 vs. Neutral (P?0.05). Lower [diffHb] was seen at 1 and 10 min in Cold 2 vs. Neutral by 13.5 ± 1.2 µM and 15.3 ± 1.4 µM and Cold 1 by 10.4 ± 3.1 µM and 11.1 ± 4.1 µM, respectively (P?0.05). During running, [tHb] was lower in Cold 2 vs. Neutral at 10 min only (P = 0.004). [diffHb] was lower at 1 min in Cold 2 by 11.3 ± 3.1 µM compared to Neutral and by 13.5 ± 2.8 µM compared to Cold 1 (P?0.001). Core tissue cooling, prior to exercise, induced greater deoxygenation of the VL muscle during the early stages of exercise, irrespective of changes in blood volume. Skin cooling alone, however, did not influence deoxygenation of the VL during exercise.     

从守护者到领路人:全球图书馆界的新角色

随着信息在人们生活和社会发展中的作用发生变化,图书馆和图书馆员的角色也经历从守护者向门户再向领路人的转变。历史上,图书馆和图书馆员作为守护者为保护和传承人类文化做出了贡献,但在社会服务方面主要是为少数精英阶层提供服务;信息、知识、学习被认为是精英阶层的特权,社会大众被认为没有必要获取信息。第二次工业革命时期,人们普遍认识到基本文化素养的必要性,西方社会也逐渐形成共识,即确保每个社会成员至少接受过初等教育;此后,随着技术进步,印刷成本降低,信息能被更多人获取和利用;公共图书馆开始普及并向社会公众开放,图书馆和图书馆员发挥门户的作用,帮助人们克服获取信息的障碍;进入数字时代,图书馆仍然发挥门户的作用,确保任何人无论其身份、财富、背景如何,都不应被排除在信息获取之外。人类社会进入信息时代,信息极大丰富与信息稀缺一样,给信息获取带来了种种问题,人们需要使用批判性思维来面对海量的信息资源;图书馆需充分发挥领路人的作用,帮助社会公众提升信息素养,实现对丰富信息的有效利用,助力创建更强大、更公平、更具创新性的社会。