Student contribution in asynchronous online discussion: a review of the research and empirical exploration

The increasingly prevalent use of Internet in schools and homes has resulted in asynchronous online discussion becoming an increasingly common means to facilitate dialogue between instructors and students, as well as students and students beyond the boundaries of their physical classrooms. This article is organized into two main sections. In the first section, we review 50 empirical studies in order to identify the factors leading to limited student contribution. Limited student contribution is defined as students making few or no postings, or students exhibiting surface-level thinking or low-level knowledge construction in online discussions. We then identify the various empirically based guidelines to address the factors. In the second section, we discuss three potential guideline dilemmas that educators may encounter: (a) use of grades, (b) use of number of posting guideline, and (c) instructor-facilitation. These are guidelines where previous empirical research shows mixed results when they are implemented. Acknowledging the dilemmas is essential for educators and researchers to make informed decisions about the discussion guidelines they are considering implementing. Finally, we report two exploratory case studies on student-facilitation that we conducted. Using students as facilitators may be an alternative solution to educators who wish to avoid the instructor-facilitation guideline dilemma.     

Different visual stimuli affect muscle activation at the knee during sidestepping

Increasing knee stability via appropriate muscle activation could reduce anterior cruciate ligament (ACL) injury risk during unplanned sidestepping. High-level athletes may activate their knee muscles differently from low-level athletes when responding to quasi-game realistic versus non game-realistic stimuli. Eleven high-level and 10 low-level soccer players responded to a non game-realistic arrow-planned condition (AP), a quasi game-realistic one-defender scenario (1DS) and two-defender scenario (2DS), and an arrow-unplanned condition (AUNP), that imposed increasing time constraints to sidestep. Activation from eight knee muscles during sidestepping was measured during pre-contact and weight-acceptance. Knee flexor-extensor co-activation ratios were established. Muscle activation levels increased by approximately 27% solely in the 1DS in both sidestepping phases. In the 2DS, the shift from a flexor dominant co-activation strategy in pre-contact toward extensor dominance in weight-acceptance commenced earlier for the high-level players. Quasi game-realistic information allowed for anticipatory increases in knee muscle activation regardless of expertise levels but only when the time demands to respond were low (1DS). High-level players were better at interpreting complex game-realistic information (2DS) to activate their knee extensors earlier in preparation for single-leg landing during weight-acceptance.     

香港科技大学土工离心机先进模拟技术在岩土工程中的应用(英文)

研究目的:采用香港科技大学的先进土工离心模拟技术来研究和解决复杂的岩土工程问题。创新要点:1.验证竖向钻孔开挖技术(应力释放)对建筑纠偏的有效性;2.研究隧道坍塌对其邻近既有隧道的影响;3.研究基坑开挖对坑中既有桩基承载力的影响;4.揭示不同颗粒级配形成的土坡在水位上升和动力荷载作用下的破坏模式。研究方法:1.用香港科技大学全球首台离心机中的双向震动台(见图5)模拟地震荷载对土坡的影响;2.用香港科技大学全球第二台四轴机械手(见图6)模拟不停机情况下的钻孔开挖。重要结论:1.竖向钻孔开挖技术能有效地对建筑物进行纠偏;2.隧道坍塌会对其邻近既有隧道产生很大的附加弯矩,尤其是拱脚处的弯矩可增加多达228%;3.基坑开挖后坑中桩基的承载力取决于桩土接触面的粗糙程度,粗糙的桩-土接触面在剪切过程中倾向于发生剪胀,这会增大桩周围土的水平土压力,从而使桩基承载力增加;4.当水位上升时,颗粒均匀,级配差的松散砂土坡容易发生静态液化;相反地,颗粒级配好的松散砂土坡(风化土)不太可能发生静态液化,而只是发生整体滑动破坏;5.离心机双向震动台实验显示松散的风化岩土坡在0.3g的地震加速度作用下不会发生液化,可以抵御香港地区的地震荷载(0.08g到0.11g)。     

The Reconquest as Crusade in the Anonymous De expugnatione Lyxbonensi

De expugnatione Lyxbonensi, an intriguing account of the Christian capture of Lisbon in 1147 by a mixed force of visiting Crusaders and local Portuguese troops, offers the modern reader a unique insight into the reality of twelfth-century religious militancy. Because the anonymous author was himself one of the Crusaders, his impressions of the Portuguese are particularly illuminating. The rapid escalation of sectarian hostility throughout the Iberian peninsula during this period has generally been interpreted as a manifestation of external cultural influences. Events in Lisbon, however, present a different picture. Although the Portuguese attempted to accommodate their northern allies' religious fervour, they themselves sought to justify their aggression by claiming the far older right of reconquest. Yet beneath such protestations of religious sanction or legal legitimacy lay the more pragmatic aim of territorial expansion.     

Providing Readable Readers for Children in the Lower Primary School

Even a proficient mature reader occasionally has problems with reading. Try reading this sentence.

“that that is is not that that is not is that it is” Even when appropriate punctuation is provided to facilitate the apprehension of the linguistic structure of this sentence, its meaning is not easily evident.     

Coordination and variability in the elite female tennis serve

Enhancing the understanding of coordination and variability in the tennis serve may be of interest to coaches as they work with players to improve performance. The current study examined coordinated joint rotations and variability in the lower limbs, trunk, serving arm and ball location in the elite female tennis serve. Pre-pubescent, pubescent and adult players performed maximal effort flat serves while a 22-camera 500 Hz motion analysis system captured three-dimensional body kinematics. Coordinated joint rotations in the lower limbs and trunk appeared most consistent at the time players left the ground, suggesting that they coordinate the proximal elements of the kinematic chain to ensure that they leave the ground at a consistent time, in a consistent posture. Variability in the two degrees of freedom at the elbow became significantly greater closer to impact in adults, possibly illustrating the mechanical adjustments (compensation) these players employed to manage the changing impact location from serve to serve. Despite the variable ball toss, the temporal composition of the serve was highly consistent and supports previous assertions that players use the location of the ball to regulate their movement. Future work should consider these associations in other populations, while coaches may use the current findings to improve female serve performance.