27 research outputs found
Effect of Electron Traps on Scintillation of Praseodymium Activated Lu3Al5O12
No full textIn this paper we present the studies performed on a set of Lu3Al5O12:Pr (LuAG:Pr) crystals with praseodymium concentration between 1.5 and 10%, grown by the micro-pulling-down (muPD) technique. The research comprises the measurements of X-ray excited emission spectra and 137Cs gamma-ray pulse height spectra in a range from 78 to 600 K, and thermoluminescence glow curves. Based on experimental data we discuss the dependence of scintillation properties of Lu3Al5O12:Pr on praseodymium content and temperature. The main attention is focused on a distinct increase of scintillation yield with temperature, which we attribute to existence of shallow electron traps and their temperature-dependent contribution to scintillation of LuAG:Pr. An active role of traps is demonstrated by a novel experiment combining X-ray and laser excitation.Radiation, Radionuclides and ReactorsApplied Science
Conscious monitoring and control (reinvestment) in surgical performance under pressure.
No full textResearch on intraoperative stressors has focused on external factors without considering individual differences in the ability to cope with stress. One individual difference that is implicated in adverse effects of stress on performance is "reinvestment," the propensity for conscious monitoring and control of movements. The aim of this study was to examine the impact of reinvestment on laparoscopic performance under time pressure
Exploring the interaction between implicit and explicit processes in motor learning
No full textpublished_or_final_versionabstractHuman PerformanceDoctoralDoctor of Philosoph
Implicit motor learning promotes neural efficiency during laparoscopy.
No full textAn understanding of differences in expert and novice neural behavior can inform surgical skills training. Outside the surgical domain, electroencephalographic (EEG) coherence analyses have shown that during motor performance, experts display less coactivation between the verbal-analytic and motor planning regions than their less skilled counterparts. Reduced involvement of verbal-analytic processes suggests greater neural efficiency. The authors tested the utility of an implicit motor learning intervention specifically devised to promote neural efficiency by reducing verbal-analytic involvement in laparoscopic performance
Examining the effect of reduced action capabilities on defensive anticipation in a 1-vs-1 task
No full textThis study used small-sided games (SSGs) to induce fatigue and therefore, reduce the action capabilities of Varsity soccer players (n= 20). The aim was to examine the effect of compromised action capabilities on defensive movement response in a 1-vs-1 scenario. Action capabilities were assessed via countermovement jumps (CMJ), 5-m acceleration, 20-m sprint and a Change of Direction (COD) test. Defensive movement response was measured via a Soccer-Specific Anticipation Test (SSAT). Following SSGs, significant reductions were observed in jump (p=.04, d=.31), acceleration (p<.001, d=.98), and sprint (p<.001, d=.66) performance. Significantly, players tended to move earlier in the SSAT following SSGs (p=.049, d=.66). Furthermore, to examine the distinct effect of reductions in each action capability, players were categorised according to whether SSGs had a worthwhile change in CMJ, acceleration, sprint or COD performance. For each of the four measures, movements tended to be initiated earlier following SSGs, although pre-/post-SSGs differences were not significant (p =.08-.51), moderate to large effect sizes were shown (d=.56-.84). These findings intimate that compromised action capabilities influence the timing of the movement response of defensive players in 1-vs-1 situations
Understanding a player’s decision making process in team 2 sports: A systematic review of empirical evidence
No full textThree perspectives have been taken to explain decision making within team sports (information processing, recognition primed decision making and ecological dynamics perspectives) resulting in conceptual tension and practical confusion. The aim of this paper was to interrogate empirical evidence to (1) understand the process of decision making within team sports and (2) capture the characteristics of decision making expertise in a team sport context. Nine electronic databases (SPORTdiscus, PsycINFO, PsycArticles, Psych-tests, PubMed, SAGE journals online, Web of knowledge, Academic search complete and Web of science) were searched until the final return in March 2021. Fifty-three articles satisfied the inclusion criteria, and were analysed thematically and synthesisd using a narrative approach. Findings indicate that the relative absence or presence of mental representation within the decision making process depends on factors including complexity, typicality, time available and contextual priors available in the game situation. We recommend that future research should integrate concepts and methodologies prevalent within each perspective to better understand decision making within team sports before providing implications for practitioners
An examination of action capabilities and movement time during a soccer anticipation task
No full textThis study examined the anticipation responses of twenty skilled youth players who were assigned to either a change of direction (CODG) or small-sided games group (SSGG). Action capabilities were assessed via a countermovement vertical jump (CMVJ), 20 m sprint, 5 m acceleration and arrowhead change of direction (COD) test. Anticipation was measured via a soccer-specific anticipation test (SSAT), which required participants to anticipate the actions of an opposing player and intercept a pass. Pre- and post-intervention testing procedures were identical for both groups. Following training there was an overall improvement in CMVJ performance (p < 0.05, r = 0.52) for both training groups and this improvement was correlated with movement initiation in the SSAT (r = 0.61, p < 0.05). The novel findings of this study highlight that different training modes can potentially have a positive impact on anticipation performance. Further investigation focussing on an examination of the relationship between training, anticipation, and action capabilities in sport is warranted for the development of research and applied perspectives in expertise
Imaging of charge trapping in distorted carbon nanotubes by x-ray excited scanning probe microscopy
No full textWe have observed the distribution of electron trapping centers on distorted carbon nanotubes (CNTs) by a unique x-ray analysis technique that has both elemental and spatial selectivities. This technique involves the use of scanning probe microscopy (SPM) under synchrotron radiation excitation of the inner shell of carbon. The probe detects the Coulomb force that results from the relaxation of an electron bound to a defect site into the core hole state created by x-ray photon absorption. This results in a change in charge state of the defect. At the spatial resolution provided by the SPM technique, we observed the electron trapping centers distributed on the compressed and torsionally distorted CNTs. This direct association of mechanical distortion with defect sites indicates a potential risk of deterioration of electric properties during the fabrication and processing of CNT networks.Applied Science
Clarifying assumptions about intraoperative stress during surgical performance: More than a stab in the dark: Reply
No full textpublished_or_final_versionSpringer Open Choice, 21 Feb 201
Coaching player decision making in rugby union: exploring coaches espoused theories and theories in use as an indicator of effective coaching practice
No full textIntroduction:
Researchers exploring how coaches can best support the development of their players decision making within team invasion sports have often been conducted from a cognitive or ecological approach, which differ in their views regarding the presence and absence of memory representations. This difference has, in turn, resulted in practical implications that are theoretically different, but not pedagogically different. Research has categorised such approaches to coaching decision making into intentional decision making training or incidental decision making training that offer different suggestions for how coaching methods may be used within their practice. Sometimes, these categories of training have been offered as the way coaches should operate over the careful selection of coaching methods given their intentions for impact. Instead, within this study we aim to explore the pragmatic nature of coaching practice, rather than adherence only to theoretical principles or beliefs.
Materials and Methods:
In this study five English Regional Academy Rugby Union Coaches participated in a semi-structured interview, three categorised systematic observations of their coaching practice and a self-confrontation interview to explore; (i) the espoused theories coaches believe they use in practice; (ii) the theories in use within their coaching practice and; (iii) the alignment and misalignment between their espoused theories and theories in use during their coaching practice.
Results & Discussion:
Our findings demonstrate that coaches employed a balance and blend of intentional and incidental coaching methods concurrently. Coaches proposed the use of non-linear pedagogy and the manipulation of constraints to promote learning activities which captured the representative nature of the competitive decision making environment. Yet also promoted the role and importance of shared mental models, tactical frameworks, off field video analysis and deliberate if–then rules of thumb when supporting the development of their players decision making. Thematic analysis extracted from interview data regarding coaches espoused theories, alongside the coaches theories in use, captured through categorised frequencies of coach behaviours and learning activities through systematic observations, present clear misalignments between proposed coaching methods and those used in practice. Misalignments were apparent for learning activities, where coaches espoused the need for representative practice but used more single-phase and huddle based scenarios, and coach behaviours, where coaches espoused the importance of setting problems for their participants through divergent questioning, yet used more instructional behaviours and convergent questions leading players toward a shared mental model of collective decision making behaviour. From our findings, we offer practical implications to coaches which suggest that when supporting player decision making, coaches should consider using their judgment to select the appropriate evidence-informed coaching method given their wider intentions for impact in the session and the context in which they operate. Furthermore, we offer a suggestion to coaches and researchers where we encourage the exploration of the chain and gap between what coaches they think they do, and what they actually do in practice as a means for critical reflection.</p
