Quadriceps EMG muscle activation during accurate soccer instep kicking

Six competitive soccer players were recruited to examine EMG activation in three quadriceps muscles during a kicking accuracy task. Participants performed three maximum instep place kicks of a stationary ball, 11 m perpendicular from the centre of the goal line towards targets (0.75 m(2)) in the four corners of the goal. Surface EMG of the vastus lateralis, vastus medialis, and rectus femoris of the kicking leg was normalized and averaged across all participants to compare between muscles, targets, and the phase of the kick. Although no significant difference were observed between muscles or kick phases, kicks to the right targets produced significantly greater muscle activity than those towards the left targets (P < 0.01). In addition, kicks towards the top right target demonstrated significantly greater muscle activity than towards the top and bottom left (P < 0.01). Under accurate soccer shooting conditions, kicks aimed to the top right corner of the goal demonstrated a higher level of quadriceps muscle activation than those towards the other corners.     

More is different: how aggregation turns on the light

The reductionist approach to science seeks to understand the behaviour of systems by studying their individual components. It has been an enormously productive approach, but it is also widely acknowledged now that in some systems the behaviour of interest is an emergent property that cannot be discerned in the separate parts. Biology is replete with such examples, from the flocking of birds to the way metabolic processes in cells rely on a dynamic interplay of proteins and other components.Yet molecular systems do not have to be particularly complex before their properties become more than the sum of the parts. A classic example is the appearance of bulk-like metallic behaviour in small clusters of metal atoms only once they exceed a certain critical size. One of the most striking instances became apparent in 2001, when Ben Zhong Tang of the Hong Kong University of Science and Technology and his co-workers found that heterocyclic silicon-containing molecules called siloles become luminescent as nanoscopic aggregates even though the individual molecules in dilute solution do not emit light [1]. This looked like the opposite of the well-known phenomenon of concentration quenching, in which energy transfer between fluorescent (generally organic) molecules quenches the emission, an effect explained in 1955 [2]. Aggregation-induced ‘switching off’ is intuitively understandable, but ‘switching on’ due to aggregation was more surprising.Yet this effect of ‘aggregation-induced emission’ (AIE), as Tang and colleagues called it, was apparently seen, but not understood, much earlier [3]. In the 1850s, George Stokes noted that some inorganic complexes were fluorescent in the condensed, solid state but not in solution. At first, AIE was seen as a curiosity and deemed likely to be rare. However, subsequent research has shown not only that it is a rather common effect but also that it can be considered just one manifestation of a wide range of behaviours that arise from aggregation—leading to the proposed field of ‘aggregate science’, manifesting at the supramolecular level of small clusters or groups of molecules held together by relatively weak interactions. The field might be considered to illustrate George Whitesides’ notion of a chemistry ‘beyond the molecule’ [4], which bridges disciplines ranging from colloid science to crystal growth, nanotechnology, liquid crystals, photochemistry and molecular biology. At the same time, it echoes the famous insight of physicist Philip Anderson about emergent phenomena and the hierarchical nature of science: ‘More is different’ [5]. An ability to switch properties on and off by controlling intermolecular interactions and aggregation suggests various applications, from optical device technologies to targeted drugs for cancer therapy [6].NSR spoke to Ben Zhong Tang about the origins and possibilities of the field.

NSR: It seems you noticed AIE in 2001 by accident. How did it come about? Tang: Yes, it was serendipity. Development of new light emitters for the fabrication of organic light-emitting diodes was a hot topic at that time. We were trying to make new luminophores [light-emitting molecules] with high efficiencies and novel structures. Attracted by the aesthetically pleasing molecular structures of siloles, I asked my students to prepare various silole compounds. One day, a student told me that he could not see any luminescence when he used a UV lamp to excite the solution of the silole compound he had made. This surprised me, because I myself prepared a silole compound when I was a PhD student and I remember that its crystal was luminescent. I sensed something strange and immediately rushed to the lab. After careful verification and discussion with the student, we concluded that both of us were correct: the silole solution was not luminescent (his observation was right) but the silole powder was emissive (my memory was right). The non-luminescent molecular species in the dilute solution were induced to emit light through formation of aggregates in the solid state. We termed the process aggregation-induced emission or AIE.

A mesoscopic aggregate can have a property that its molecular species does not exhibit at all.—Ben Zhong Tang

Open in a separate windowBen Zhong Tang of the Hong Kong University of Science and Technology, China (Courtesy of Ben Zhong Tang). NSR: The phenomenon seemed to defy conventional expectations. Did you have trouble persuading others—or yourselves!—that it was real? Tang: I initially thought the student might have done something wrong, for the phenomenon he observed was totally unexpected. The common belief in the community of photophysics research is that luminescence from an organic dye generally weakens when its molecules are aggregated, an effect often referred to as aggregation-caused quenching or ACQ. I was shocked when I realized that the silole luminogen was showing an anti-ACQ effect. Still, I felt lucky to encounter something ‘abnormal’. No matter how odd a phenomenon seems, if it can be repeatedly observed, it must be real. We repeated our experiments many times and we were eventually convinced that the AIE effect was true. We had trouble, however, to understand why the silole luminogen behaved in such a way that was diametrically opposed to conventional ACQ. NSR: Are there any historical precedents—experiments in which this effect might have been glimpsed previously, but not recognized as such? Tang: When we published our first AIE paper in 2001, we thought the photophysical effect was unprecedented. However, we gradually found out that similar phenomena had been previously observed by other scientists. For example, in 1853 George Stokes reported in a paper that some inorganic platinocyanide salts ‘are sensitive’ (meaning luminescent in modern terminology) ‘only in the solid state’ but ‘their solutions look like mere water’. Sadly, he didn’t follow it up. Other people have made similar observations in different dye systems, which were, however, not recognized as AIE processes. Partially because of this, we had great difficulty in finding relevant reference papers. As a matter of fact, Stokes’ report, published in the mid-19th century, was not known to us until the middle of 2018. However, we are not surprised by those early works, for we understand that science progresses not in an abrupt but in a continuous way. George Smith articulated this: ‘Very few research breakthroughs are novel. Virtually all of them build on what went on before.’ A discovery is often a happenstance. We happened to have ‘rediscovered’ a very old but largely unnoticed phenomenon. Luckily, we grasped the opportunity to see more and farther by standing on the shoulders of giants.     

Thinking Thru Making: Mapping Computational Thinking Practices onto Scientific Reasoning

Journal of Science Education and Technology - This paper shares findings from a teacher designed physics and computing unit that engaged students in learning physics and computing concurrently thru...     

Different centre of pressure patterns within the golf stroke II: Group-based analysis

Abstract

Although the golf coaching literature stresses the importance of weight transfer during the swing, research has been conflicting or lacking statistical support. A potential problem with previous studies is that no attempt was made to account for different movement strategies in the golf swing. This study evaluated the relationship between centre of pressure measures and club head velocity within two previously identified swing styles, the “Front Foot” and “Reverse” styles. Thirty-nine Front Foot golfers and 19 Reverse golfers performed swings with a driver while standing on two force plates. From the force plate data, centre of pressure displacement, velocity, range, and timing parameters were calculated. Correlation and regression analysis indicated that a larger range of centre of pressure and a more rapid centre of pressure movement in the downswing was associated with a larger club head velocity at ball contact for the Front Foot group. For the Reverse golfers, positioning the centre of pressure further from the back foot at late backswing and a more rapid centre of pressure transfer towards the back foot at ball contact was associated with a larger club head velocity at ball contact. This study has highlighted the importance of identifying different movement strategies before evaluating performance measures, as different parameters were found to be important for the Front Foot and Reverse styles.     

Allocation of academic staff in universities

This article is concerned with allocation of academic staff between departments in a university. The article considers general principles of staff allocation and then goes on to consider specific techniques for university staff allocation. Practical problems likely to be associated with implementing the results of a given method of staff allocation are also discussed. Finally the question of decentralised decision-making and possibility of allowing some freedom of choice between appointment of academic staff and other resources is considered.     

The ordinary school – what is it?

In this paper we describe some of the complexities involved in the construction of a sample of ‘ordinary’ schools. We outline the policy context in England that produces pressures to resist ‘ordinariness’. The paper then explores two theoretical tools, fabrication and rhetoric, that are deployed in an analysis of some key artefacts of fabrication from schools in England. Through an examination of artefacts such as school brochures and websites, this paper asks whether there are any ‘ordinary’ schools in these performative times?