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The effect of quenched (frozen) orientational disorder on the collective motion of active particles is analyzed. We find that, as with annealed disorder (Langevin noise), active polar systems are far more robust against quenched disorder than their equilibrium counterparts. In particular, long ranged order (i.e., the existence of a non-zero average velocity $\langle {\bf v} \rangle$) persists in the presence of quenched disorder even in spatial dimensions $d=3$, while it is destroyed even by arbitrarily weak disorder in $d \le 4$ in equilibrium systems. Furthermore, in $d=2$, quasi-long-ranged order (i.e., spatial velocity correlations that decay as a power law with distance) occurs when quenched disorder is present, in contrast to the short-ranged order that is all that can survive in equilibrium. These predictions are borne out by simulations in both two and three dimensions., 22 pages, 6 figures. The long paper on flocking with quenched noise

Empirical evidence demonstrates that performing artists are confronted by a variety of ‘bodily crises’ (e.g., injury, attrition of habits induced by ageing) over the course of their careers (Wainwright, Williams, & Turner, 2005). Such crises may present a serious threat to the embodied subject. Unfortunately, many prominent theories of skill acquisition (e.g., Fitts & Posner, 1967) appear to evacuate the body from performance by suggesting that any form of conscious processing (i.e., paying conscious attention to one's action during motor skill execution) will disrupt habitual behaviour. As a result, few researchers have considered how performers might tackle bodily anomalies. In the current paper, we seek to address this issue by discussing a variety of the ‘crises’ that confront the performing body. We start by discussing a number of disciplinary practices that may contribute to these crises. Next, we argue that habitual movements must be open to ‘acts of creativity’ in order to maintain a productive relationship between the performing body and the environment. Then we consider what this ‘creative action’ might involve and discuss a number of approaches (e.g., mindfulness, somaesthetic awareness) that could maintain and improve one's movement proficiency. Here, our argument draws on Dewey's (1922) pragmatist philosophy and his belief that ‘intelligent habit’ was required to help people to improve their movement functioning. Finally, we consider the implications of our argument for current conceptualisations of ‘habitual’ movement and recommend that researchers explore the adaptive and flexible capacity of the performing body.

Low levels of symptom recognition by staff have been "gateway" barriers to the management of depression in long-term care. The study aims were to refine a depression training program for front-line staff in long-term care and provide evaluative knowledge outcome data. Three primary training modules provide an overview of depression symptoms; a review of causes and situational and environmental contributing factors; and communication strategies, medications, and clinical treatment strategies. McNemar's chi-square tests and paired t-tests were used to examine change in knowledge. Data were analyzed for up to 143 staff members, the majority from nursing. Significant changes (p

A number of influential theories of skill acquisition posit that the performing body is an absent presence during “habitualized” action. The current article counters this claim by drawing on a wide range of empirical and phenomenological evidence to argue that the body is never forgotten during skilled movement. We draw on Colombetti’s (2011) taxonomy of the bodily self to show how skilled performers may experience either a reflective or prereflective mode of bodily awareness depending on the foci of attention adopted during online skill execution. We argue that it is the dynamic interplay of these latter forms of bodily awareness that facilitates optimal performance and allows skilled performers to confront the challenges (e.g., injury, performance slumps) that are a ubiquitous feature of competitive environments.

Classical theories of skill acquisition propose that automatization (i.e., performance requires progressively less attention as experience is acquired) is a defining characteristic of expertise in a variety of domains (e.g., Fitts & Posner, 1967 ). Automaticity is believed to enhance smooth and efficient skill execution by allowing performers to focus on strategic elements of performance rather than on the mechanical details that govern task implementation ( Williams & Ford, 2008 ). By contrast, conscious processing (i.e., paying conscious attention to one's action during motor execution) has been found to disrupt skilled movement and performance proficiency (e.g., Beilock & Carr, 2001 ). On the basis of this evidence, researchers have tended to extol the virtues of automaticity. However, few researchers have considered the wide range of empirical evidence which indicates that highly automated behaviors can, on occasion, lead to a series of errors that may prove deleterious to skilled performance. Therefore, the purpose of the current paper is to highlight the perils, rather than the virtues, of automaticity. We draw on Reason's (1990) classification scheme of everyday errors to show how an overreliance on automated procedures may lead to 3 specific performance errors (i.e., mistakes, slips, and lapses) in a variety of skill domains (e.g., sport, dance, music). We conclude by arguing that skilled performance requires the dynamic interplay of automatic processing and conscious processing in order to avoid performance errors and to meet the contextually contingent demands that characterize competitive environments in a range of skill domains.

We conducted a cluster randomized controlled trial (RCT) to test the effects of a self-determination theory-based intervention on athlete motivation and burnout. In addition, we examined the feasibility and acceptability of the intervention. We randomly assigned youth Gaelic football coaches (N = 6) and their teams to an experimental or a delayed treatment control group (n = 3 each group). We employed linear mixed modeling to analyze changes in player motivation and burnout as a result of their coach participating in a 12-week SDT-based intervention. In addition, we conducted a fidelity assessment to examine whether the intervention was implemented as planned. The findings demonstrated the feasibility and acceptability of implementing a self-determination theory-based intervention in the coaching domain. In addition, this study demonstrated favorable trends in the quality of player motivation and burnout symptoms as a result of an SDT-based intervention.

Objectives We examined how stress appraisals were associated with emotions, coping behaviours, as well as subjective and objective measures of performance. Design Prospective field- and laboratory-based studies. Methods In Study 1, 192 athletes completed process-oriented psychometrics pertaining to the aforementioned constructs throughout a sporting competition. Study 2 utilised an experimental design to assess the causal influence of stress appraisals on performance, cortisol, and psychological variables. Thirty gender-matched athletes were randomly assigned to either a stress appraisal (e.g., challenge, threat, benefit, or harm/loss) or the control group. Participants completed three 16.1 km cycling time trials (TT) on a cycle ergometer, with their appropriate stress appraisal engendered via falsified performance feedback throughout the final TT. Salivary cortisol samples and psychometrics (e.g., appraisals, emotions, and coping) were collected before and after each TT. Results The results of Study 1 revealed a sequential link between challenge stress appraisals and perceived goal attainment via pleasant emotions and task-oriented coping behaviours. Threat stress appraisals inversely related to goal attainment via unpleasant emotions and both distraction- and disengagement-oriented coping. In Study 2, no significant psychophysiological or performance differences were found across genders. The temporal orientation of stress appraisals influenced objective cycling TT performance. Benefit and harm/loss stress appraisals significantly facilitated or inhibited performance, respectively. Cortisol spikes were observed in the stress appraisal group’s threat, challenge, and benefit, with a decline detected within the harm/loss group. Whilst the process of winning is physiologically stressful, the fear of defeat may be more stressful than losing itself. Conclusion Stress appraisals influence subjective and objective performance, as well as neuroendocrine and psychological responses to stress.

Coaches overseeing technical changes, which are driven by the desire to enhance performance, are a very common part of the coaching process among tennis players. A number of psychosocial concomitants (e.g. confidence) appear important in influencing an athlete/coach’s ability to successfully implement such refinements. The current study explored this issue by conducting a series of semi-structured interviews with highly-skilled tennis players who have attempted to extensively refine an aspect of their technique. Remaining confident and committed to the changes prescribed by their coach were more likely to make refinement successful. Our data suggests the need for better communication between the coach and athlete at the initiation of the refinement and throughout the process.

We study the hydrodynamic behavior of three-dimensional (3D) incompressible collections of self-propelled entities in contact with a momentum sink in a state with nonzero average velocity, hereafter called 3D easy-plane incompressible polar active fluids. We show that the hydrodynamic model for this system belongs to the same universality class as that of an equilibrium system, namely, a special 3D anisotropic magnet. The latter can be further mapped onto yet another equilibrium system, a DNA-lipid mixture in the sliding columnar phase. Through these connections we find a divergent renormalization of the damping coefficients in 3D easy-plane incompressible polar active fluids, and obtain their equal-time velocity correlation functions.

We review recent results on the coherence and superfluidity of driven dissipative condensates, i.e., systems of weakly interacting nonconserved bosons, such as polariton condensates. The presence of driving and dissipation has dramatically different effects depending on dimensionality and anisotropy. In three dimensions, equilibrium behaviour is recovered at large scales for static correlations, while the dynamical behaviour is altered by the microscopic driving. In two dimensions, for an isotropic system, drive and dissipation destroy the algebraic order that would otherwise exist; however, a sufficiently anisotropic system can still show algebraic phase correlations. We discuss the consequences of this behaviour for recent experiments measuring phase coherence and outline potential measurements that might directly probe superfluidity. Introduction This chapter is dedicated to superfluidity and its relation to Bose-Einstein condensation (BEC), a topic with a long history. Many reviews of the concepts of condensation and superfluidity in thermal equilibrium can be found; see for example Refs. [1, 2, 3, 4]. The focus of this chapter is on how these concepts apply (or fail to apply) to driven dissipative condensates – systems of bosons with a finite lifetime, in which loss is balanced by continuous pumping. We focus entirely on the steady state of such systems, neglecting transient, time-dependent behaviour. Experimentally, the most studied example of a driven dissipative condensate has been microcavity polaritons, an overview of which is given in Ref. [5] and Chapter 4. However, similar issues can arise in many other systems, most obviously photon condensates [6] (see also Chapter 19), magnon condensates [7] (see also Chapters 25–26), and potentially exciton condensates (although typical exciton lifetimes are much longer than for polaritons). Even experiments on cold atoms (see, e.g., Chapter 3) could be driven into a regime in which such physics occurs, when considering continuous loading of atoms balancing threebody losses [8] or atom laser setups [9, 10, 11]. Experiments on polaritons are two-dimensional, and in two dimensions it is particularly important to clearly distinguish three concepts often erroneously treated as equivalent: superfluidity, condensation, and phase coherence. This is because no true Bose-Einstein condensate exists in a homogeneous two-dimensional system.

What exactly is “concentration”, and how is it related to the broader psychological construct of attention? what theories and metaphors best help us to understand attentional processes? why do skilled performers “lose” their concentration? what are the building blocks of effective concentration? how is attention related to situational awareness and visual-perceptual skills? The chapter presents answers for these questions using the principles and findings of cognitive psychology – a discipline that studies how the mind works in acquiring, storing and using knowledge. In psychology, the term “attention” refers to a cognitive system that facilitates the selection of some stimuli for further processing while inhibiting that of other stimuli. In sport and performance psychology, considerable research has been conducted on how experts and novices use their perceptual system to guide their attention. In psychology, “pupillometry” is the objective measurement of mental effort though task-evoked changes in the diameter of the pupil of the eye during cognitive processing.

Quality of life assessment includes measurement of positive affect. Methods artifacts associated with positively and negatively worded items can manifest as negative items loading on a second factor, despite the conceptual view that the items are measuring one underlying latent construct. Negatively worded items may elicit biased responses. Additionally, item-level response bias across ethnically diverse groups may compromise group comparisons. The aim was to illustrate methodological approaches to examining method factors and measurement equivalence in an affect measure with 9 positively and 7 negatively worded items: The Feeling Tone Questionnaire (FTQ). The sample included 4,960 non-Hispanic White, 1,144 non-Hispanic Black, and 517 Hispanic community and institutional residents receiving long-term supportive services. The mean age was 82 (s.d.=11.0); 73% were female. Two thirds were cognitively impaired. Methods effects were assessed using confirmatory factor analyses (CFA), and reliability with McDonald’s omega and item response theory (IRT) generated estimates. Measurement equivalence was examined using IRT-based Wald tests. Methods effects associated with negatively worded items were observed; these provided little IRT information, and as a composite evidenced lower reliability. Both 13 and 9 item positive affect scales performed well in terms of model fit, reliability, IRT information, and evidenced little differential item functioning of high magnitude or impact. Both CFA and IRT approaches provided complementary methodological information about scale performance. The 9-item affect scale based on the FTQ can be recommended as a brief quality-of-life measure among frail and cognitively impaired individuals in palliative and long-term care settings.

We are constantly bombarded by information. Therefore, during every waking moment of our lives, we face decisions about which stimuli to prioritize and which ones to ignore. To complicate matters, the information that clamors for our attention includes not only events that occur in the world around us but also experiences that originate in the subjective domain of our own thoughts and feelings. The end result is that our minds can consciously attend to only a fraction of the rich kaleidoscope of information and experiences available to us from our senses, thoughts, memories, and imagination. Attentional processes such as “concentration,” or the ability to focus on the task at hand while ignoring distractions, are crucial for success in sport and other domains of skilled performance. To illustrate, Venus Williams, one of the greatest tennis players of all time, proclaimed that “for the players it is complete and pure focus. You don’t see anything or hear anything except the ball and what’s going on in your head.” For psychological scientists, concentration resembles a mental spotlight (like the head-mounted torch that miners and divers wear in dark environments) that illuminates targets located either in the external world around us or in the internal world of our subjective experiences. A major advantage of this spotlight metaphor is that it shows us that concentration is never “lost”—although it can be diverted to targets (whether in the external world or inside our heads) that are irrelevant to the task at hand. Research on attentional processes in sport and performance has been conducted in cognitive psychology (the study of how the mind works), cognitive sport psychology (the study of mental processes in athletes), and cognitive neuroscience (the study of how brain systems give rise to mental processes). From this research, advances have been made both in measuring attentional processes and in understanding their significance in sport and performance settings. For example, pupillometry, or the study of changes in pupil diameter as a function of cognitive processing, has been used as an objective index of attentional effort among skilled performers such as musicians and equestrian athletes. Next, research suggests that a heightened state of concentration (i.e., total absorption in the task at hand) is crucial to the genesis of “flow” states (i.e., rare and elusive moments when everything seems to come together for the performer) and optimal performance in athletes. More recently, studies have shown that brief mindfulness intervention programs, where people are trained to attend non-judgmentally to their own thoughts, feelings, and sensations, offer promise in the quest to enhance attentional skills in elite athletes. By contrast, anxiety has been shown to divert skilled performers’ attention to task-irrelevant information—sometimes triggering “choking” behavior or the sudden and significant deterioration of skilled performance. Finally, concentration strategies such as “trigger words” (i.e., the use of short, vivid, and positively phrased verbal reminders such as “this ball now”) are known to improve athletes’ ability to focus on a specific target or to execute skilled actions successfully.

The dynamics of self-locomotion of active particles in aligned or liquid crystalline fluids strongly deviates from that in simple isotropic media. We explore the long-time dynamics of a swimmer moving in a three-dimensional smectic liquid crystal and find that the mean-square displacement (MSD) transverse to the director exhibits a distinct logarithmic tail at long times. The scaling is distinctly different from that in an isotropic or nematic fluid and hints at the subtle but important role of the director fluctuation spectrum in governing the long-time motility of active particles. Our findings are based on a generic hydrodynamic theory and Brownian dynamics computer simulation of a three-dimensional soft mesogen model., Comment: 12 pages, 2 figures

Dreyfus and Dreyfus’ (1986) influential phenomenological analysis of skill acquisition proposes that expert performance is guided by non-cognitive responses which are fast, effortless and apparently intuitive in nature. Although this model has been criticised (e.g., by Breivik Journal of Philosophy of Sport, 34, 116–134 2007, Journal of the Philosophy of Sport, 40, 85–106 2013; Eriksen 2010; Montero Inquiry: An interdisciplinary Journal of Philosophy, 53, 105–122 2010; Montero and Evans 2011) for over-emphasising the role that intuition plays in facilitating skilled performance, it does recognise that on occasions (e.g., when performance goes awry for some reason) a form of ‘detached deliberative rationality’ may be used by experts to improve their performance. However, Dreyfus and Dreyfus (1986) see no role for calculative problem solving or deliberation (i.e., drawing on rules or mental representations) when performance is going well. In the current paper, we draw on empirical evidence, insights from athletes, and phenomenological description to argue that ‘continuous improvement’ (i.e., the phenomenon whereby certain skilled performers appear to be capable of increasing their proficiency even though they are already experts; Toner and Moran 2014) among experts is mediated by cognitive (or executive) control in three distinct sporting situations (i.e., in training, during pre-performance routines, and while engaged in on-line skill execution). We conclude by arguing that Sutton et al. Journal of the British Society for Phenomenology, 42, 78–103 (2011) ‘applying intelligence to the reflexes’ (AIR) approach may help to elucidate the process by which expert performers achieve continuous improvement through analytical/mindful behaviour during training and competition.

The hydrodynamic equations of dry active polar fluids (i.e., moving flocks without momentum conservation) are shown to imply giant number fluctuations. Specifically, the rms fluctuations $\sqrt {}$ of the number $N$ of active particles in a region containing a mean number of active particles $$ scales according to the law $\sqrt {} = K'^{\phi(d)}$ with $\phi(d)=\frac{7}{10}+\frac{1}{5d}$ in $d\le4$ spatial dimensions. This is much larger the "law of large numbers" scaling $\sqrt {} = K\sqrt{}$ found in most equilibrium and non-equilibrium systems. In further contrast to most other systems, the coefficient $K'$ also depends singularly on the shape of the box in which one counts the particles, vanishing in the limit of very thin boxes. These fluctuations arise {\it not} from large density fluctuations - indeed, the density fluctuations in \dry s are not in general particularly large - but from long ranged spatial correlations between those fluctuations. These are shown to be closely related in two spatial dimensions to the electrostatic potential near a sharp upward pointing conducting wedge of opening angle ${3\pi\over8}=67.5^\circ$, and in three dimensions to the electrostatic potential near a sharp upward pointing charged cone of opening angle $37.16^\circ$. This very precise prediction can be stringently tested by alternative box counting experiments that directly measure this density-density correlation function., Comment: 23 pages; Invited contribution to Journal of Chemical Physics Special Issue on Active Matter

The use of surveillance technologies as tools to encourage performance enhancement has become an accepted component of elite coaching. Those from the communities of sports physiology, psychology and biomechanics who promote the application of surveillance technologies have reported multiple benefits for the athlete. Conversely, several socio-cultural studies have suggested that surveillance technologies can lead to an oppressive mechanism of control over the athlete, significantly altering the role and responsibilities of the contemporary coach. In this critical commentary we use a post-structural position and adopt Foucault’s disciplinary analysis to contribute to the ongoing debate surrounding the use of surveillance technology in sport. Specifically, we achieve this by labelling surveillance technologies in sport as what Foucault (1977) might call, instruments of discipline, and by explaining the impact they have upon the working coach and the skilled athlete. We present some suggestions surrounding how to most appropriately utilise surveillance technologies in a sports coaching context and conclude by warning against a binary consideration of the use of technology as either good or bad.

Abdollahipour, Wulf, Psotta, and Nieto (2015) recently published data in the Journal of Sports Sciences to show that an external focus of attention promotes superior performance effects (gymnastics jump height and judged movement form score) when compared to internal or control foci during skill execution without an implement involved. While we do not contest the veracity of findings reported, nor others that have been used to support beneficial effects of an external focus of attention, in this Letter to the Editor we comment on considerable methodological limitations associated with this and previous studies that, we suggest, have resulted in serious theoretical oversights regarding the control of movement and, most crucially from our practitioner perspective, suboptimal recommendations for applied coaching practice. Specifically, we discuss the lack of consideration towards translational research in this area, the problematic nature of attentional focus cues employed, interpretation of findings in relation to other applied recommendations and coherence with mechanistic underpinning and, finally, the representative nature of task involved. In summary, while (laboratory) research evidence may appear to be conclusive, we suggest that the focus of attention effects are in need of more ecologically valid and rigorous testing as well as consideration of current coaching practices if it is to optimally serve the applied sporting domain that it purportedly aims to.

Active (i.e., self-propelled or swimming) particles moving through an isotropic fluid exhibit conventional diffusive behavior. We report anomalous diffusion of an active particle moving in an anisotropic, nematic background. Whilst the translational motion parallel to the nematic director shows ballistic behavior, the long-time transverse motion is super-diffusive, with an anomalous scaling $\propto t \ln t$ of the mean squared displacement with time $t$. This behavior is predicted by an analytical theory that we present here, and is corroborated by numerical simulation of active particle diffusion in a simple lattice model for a nematic liquid crystal. It is universal for any collection of self-propelled elements (e.g., bacteria or active rods) moving in a nematic background, provided only that the swimmers are sufficiently dilute that their interactions with each other can be neglected, and that they do not perform "hairpin" turns., Comment: 12 pages, 3 figures

This paper is centered on the principle author's (John) personal narrative of a coach-athlete relationship in golf, and how the original story altered through a process of shared critical thinking. On first telling, John explained to his co-authors how he considered himself to be the victim of bad coaching practice following his coach's failure to correctly diagnose a key but subtle fault with his golf swing. The initial rendering was a story of blame, betrayal, and of a coach who ultimately failed to provide the expert service required. Having shared and critically reflected upon this comfortable version of events with his co-authors, John explores how he came to understand his role in an ultimately dysfunctional coaching relationship in a different way. Rather than being a blameless victim, John began to explore his own contribution to the process of relationship breakdown. For example, his conscious decision to not share his thoughts and feelings about his golf swing with his coach; an act of stubbornn...

Researchers have suggested that skill performance deteriorates when people try to exert conscious control over automatic actions. Unfortunately, little is known about the effects of different types of conscious processing on skilled performance by expert athletes. We conducted two experiments to address this issue. Experiment 1 investigated the influence of a specific form of conscious control (making technical adjustments to a stroke) on the putting skills of expert golfers. The expert golfers maintained putting proficiency (i.e. number of putts holed) when making technical adjustments. However, this form of conscious processing altered the timing and consistency of golfers' putting strokes. Experiment 2 compared the influence of technical adjustments and conscious monitoring (paying attention to the execution of the stroke) on expert golfers' putting skills. Technical adjustments had no disruptive influence on expert golfers' putting proficiency but did reduce the consistency of their strokes. However, conscious monitoring was found to impair putting proficiency. The implications of the work for theory and future work are discussed.

Two previous papers presented a conjectured model of quality of life featuring the personal management of accessing choices and choosing among them (the c-c process). Those papers made the case that this model unifies the pathways leading to impaired quality of life, especially with regard to age associated multiple co-morbidities, changes in perception and functioning, and the effects of long term care environments; it also introduces a science base for understanding and guiding interventions that can assist people to achieve their quality-of-life goals. Our aim in this paper is to outline interprofessional strategies that could relieve restrictions or distortions of the c-c process imposed by aging, ill-health, or a restricting environment. We do so by outlining potential deficits in the c-c process and matching these with restorative person-centered interprofessional interventions including interprofessional teamwork. Findings suggest that interprofessional assessment and team work is well suited to assisting the c-c process. We conclude that the groundwork has been prepared for developing training programs and clinical trials for interprofessional interventions targeting the c-c process.

VERITAS is an array of four, 12-m-diameter, Cherenkov telescopes, designed to explore the very-high-energy gamma-ray sky in the energy band between 100 GeV and 50 TeV. Its construction and commissioning have occurred over the past two years and the array has been taking scientific data with three or more telescopes since November 2006. We present results from observations made with VERITAS during the past observing season, including new results on the distant blazar 1ES 1218 + 304 , the active galaxy M87 and the high-mass X-ray binary system LS I + 61 303. We also describe the plans in place for the coming observing seasons.

Details are presented of the Whipple Observatory’s 10 m atmospheric Cherenkov telescope and camera, as it evolved during the period 1997 until 2006. The design of the telescope and camera’s optical and electronic systems is discussed together with a detailed description of the four-stage GRANITE (Gamma-RAy New Imaging TElescope) upgrade program, undertaken during the same time period. The objective of the upgrade was to improve the telescope’s sensitivity for the detection of very-high-energy gamma-rays. Results from the program are provided and are briefly discussed in the context of the design of VERITAS.

Gamma-ray burst (GRB) observations at very high energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and plerions, in which the GRB spectral energy distribution has a double-peaked shape extending into the VHE regime. VHE emission coincident with delayed X-ray flare emission has also been predicted. GRB follow-up observations have had high priority in the observing program at the Whipple 10m Gamma-ray Telescope and GRBs will continue to be high priority targets as the next generation observatory, VERITAS, comes on-line. Upper limits on the VHE emission, at late times (>~4 hours), from seven GRBs observed with the Whipple Telescope are reported here., Accepted for publication in the January 20, 2007 volume of the Astrophysical Journal, 655, 396

We study the asymptotic response of polar ordered active fluids ("flocks") to small external aligning fields $h$. The longitudinal susceptibility $\chi_{_\parallel}$ diverges, in the thermodynamic limit, like $h^{-\nu}$ as $h \rightarrow 0$. In finite systems of linear size $L$, $\chi_{_\parallel}$ saturates to a value $\sim L^\gamma$. The universal exponents $\nu$ and $\gamma$ depend only on the spatial dimensionality $d$, and are related to the dynamical exponent $z$ and the "roughness exponent" $\alpha$ characterizing the unperturbed flock dynamics. Using a well supported conjecture for the values of these two exponents, we obtain $\nu = 2/3$, $\gamma = 4/5$ in $d = 2$ and $\nu = 1/4$, $\gamma = 2/5$ in $d = 3$. These values are confirmed by our simulations., Comment: 20 pages, 3 figures, accepted for publication in New Journal of Physics

In a recent paper ( Toner & Moran, 2015 ), we argued that continued improvement among elite athletes requires alternation between external and internal foci of attention. In her commentary on this paper, Wulf (2015) claims that we have misunderstood the ‘attentional focus’ effect. Our rejoinder has three objectives. Firstly , we critically evaluate Wulf's arguments and counter her false allegations and spurious reasoning. Secondly , we explain our concerns about certain aspects of attentional focusing research. Finally , we propose that in order to explore the dynamic nature of attentional focusing, we need to go beyond restrictive theoretical dichotomies (e.g., “internal” versus “external” processes) using new approaches.

A key postulate of traditional theories of motor skill-learning (e.g., Fitts and Posner, 1967; Shiffrin and Schneider, 1977) is that expert performance is largely automatic in nature and tends to deteriorate when the performer 'reinvests' in, or attempts to exert conscious control over, proceduralized movements (Masters and Maxwell, 2008). This postulate is challenged, however, by recent empirical evidence (e.g., Nyberg, in press; Geeves et al., 2014) which shows that conscious cognitive activity plays a key role in facilitating further improvement amongst expert sports performers and musicians – people who have already achieved elite status (Toner and Moran, in press). This evidence suggests that expert performers in motor domains (e.g., sport, music) can strategically deploy conscious attention to alternate between different modes of bodily awareness (reflective and pre-reflective) during performance. Extrapolating from this phenomenon, the current paper considers how a novel theoretical approach (adapted from Sutton et al., 2011) could help researchers to elucidate some of the cognitive mechanisms mediating continuous improvement amongst expert performers. Author has checked copyright

This chapter provides students with some guidelines and recommendations on how to assess the quality of published quantitative research in the field of sports coaching. It outlines the most important practical issues that researchers typically encounter when engaging in this form of research. The chapter gives some practical tips on how to evaluate quantitative research studies in sports coaching. Consequently, when judging the true effect of a statistical finding one should pay close attention to effect size statistics. Probability sampling is any sampling procedure in which each member of a target population has an equal chance of being chosen. In fact, random sampling will often be employed to avoid selection bias. Issues which may severely compromise the external validity of study findings include an insufficient sample size and inappropriate sampling method, and problems with the instrumentation or measurements used to collect the data.

Traditional theories of motor skill learning (e.g., Fitts and Posner, 1967) and many contemporary perspectives in sport psychology (see Masters and Maxwell, 2008) and cognitive neuroscience (see Yarrow et al., 2010) argue that skilled action is guided by procedural or implicit knowledge. Researchers adopting this perspective believe that skilled performance proceeds rapidly, efficiently and without the need for conscious monitoring, or a reliance on propositional knowledge (what some might term declarative or explicit knowledge) to guide an activity. However, in a recent paper published in this journal, Stanley and Krakauer (2013) present a compelling argument which offers a stern challenge to the latter of these assumptions. Drawing on evidence from famous cases in neuroscience (e.g., the case of HM) and other research on the nature of skill, Stanley and Krakauer (2013) suggest that becoming proficient at any motor task, and maintaining and improving one's skill in that activity, is heavily influenced by the use of what they refer to as “knowledge of facts” (i.e., propositional knowledge). The aim of this brief commentary is to build on Stanley and Krakauer's work by pointing to empirical evidence (e.g., Collins et al., 1999), recent theory (e.g., Shusterman, 2009) and phenomenological descriptions (e.g., Cotterill et al., 2010) which suggest that “continuous improvement” at the elite level of sport is mediated by the “ongoing accrual and improving application of knowledge of facts about an activity” (Stanley and Krakauer, 2013, p. 2). More specifically, the current paper presents evidence which demonstrates how performers use knowledge of facts in two distinct sporting situations: (1) in the training context when the performer is seeking to improve “attenuated” movement patterns and (2) during the planning and strategizing that occurs in pre-performance routines during on-line competitive performance.

The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales. The main database consists of 878.4 hours of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400 GeV with 20% uncertainty. This is the largest database of any TeV-emitting active galactic nucleus (AGN) and hence was used to explore the variability profile of Markarian 421. The time-averaged flux from Markarian 421 over this period was 0.446$\pm$0.008 Crab flux units. The flux exceeded 10 Crab flux units on three separate occasions. For the 2000-2001 season the average flux reached 1.86 Crab units, while in the 1996-1997 season the average flux was only 0.23 Crab units., Comment: 29 pages, 15 figures. Accepted for publication in Astroparticle Physics

Using a continuum model for inhomogeneous flocks, we show that a finite but arbitrarily large moving ``packet'' of active particles (e.g., moving creatures) can form in a background of a lower density disordered phase of these particles, like a liquid drop surrounded by vapor. The ``vapor density'' of the disordered background can be made arbitrarily low. We find three basic types of quasi-one-dimensional states: ``longitudinal'', ``transverse'', and ``oblique'' states, with their internal velocity fields, respectively, parallel, perpendicular, and oblique to the interface. The transitions between these states are also studied.

We show that discotics, lying deep in the columnar phase, can exhibit an x-ray scattering pattern which mimics that of a somewhat unusual smectic liquid crystal. This exotic, new glassy phase of columnar liquid crystals, which we call a ``hybrid columnar Bragg glass'', can be achieved by confining a columnar liquid crystal in an anisotropic random environment of e.g., strained aerogel. Long-ranged orientational order in this phase makes {\em single domain} x-ray scattering possible, from which a wealth of information could be extracted. We give detailed quantitative predictions for the scattering pattern in addition to exponents characterizing anomalous elasticity of the system., Comment: 4 RevTeX pgs, 2 eps figures. To appear in PRL

We report the existence of two new topologically ordered glass phases of smectics in strained aerogel. In contrast to the case of unstrained aerogel, we find compelling theoretical arguments that a smectic in uniaxially stretched aerogel exhibits, for homeotropic nematic-aerogel alignment, a `smectic Bragg glass' in the universality class of the `XY Bragg glass'. On the other hand, a uniaxial compression, with homeotropic alignment, leads to an entirely novel type of anisotropic smectic elastic glass phase that we call the `m = 1 Bragg glass'. This latter phase exhibits anomalous elasticity, characterized by exponents that we calculate to high precision. We present a phase diagram for the system in the aerogel density-strain parameter space, which should be accessible experimentally. We also make numerous other scaling predictions for experimentally observable quantities.

We predict the existence of a totally new class of phases in weakly coupled, three-dimensional stacks of two-dimensional (2D) XY-models. These ``sliding phases'' behave essentially like decoupled, independent 2D XY-models with precisely zero free energy cost associated with rotating spins in one layer relative to those in neighboring layers. As a result, the two-point spin correlation function decays algebraically with in-plane separation. Our results, which contradict past studies because we include higher-gradient couplings between layers, also apply to crystals and may explain recently observed behavior in cationic lipid-DNA complexes., 4 pages of double column text in REVTEX format and 1 postscript figure

We show that smectic liquid crystals confined in_anisotropic_ porous structures such as e.g.,_strained_ aerogel or aerosil exhibit two new glassy phases. The strain both ensures the stability of these phases and determines their nature. One type of strain induces an ``XY Bragg glass'', while the other creates a novel, triaxially anisotropic ``m=1 Bragg glass''. The latter exhibits anomalous elasticity, characterized by exponents that we calculate to high precision. We predict the phase diagram for the system, and numerous other experimental observables., 4 RevTeX pgs, 2 eps figures, submitted to Phys. Rev. Lett

We study the statistical properties and dynamics of flexible fluid membranes containing active transmembrane proteins and find that such active membranes can be either stable or unstable to small disturbances, depending on the signs of certain crucial parameters characterising the protein-membrane interaction. A major finding is that the shape-fluctuation spectrum in the stable case for a zero-tension active membrane has the same form over a large range of length scales as at equilibrium, but with a nonequilibrium "noise temperature" determined by the activity.

We have used coherent soft-x-ray dynamic light scattering at the Bragg peak to measure the thermally driven layer fluctuations in freely suspended films of five different smectic-A liquid crystals: 4O.8, 7O.7, 8CB, 8OCB, and 10OCB. The measured relaxation times at a scattering wave vector corresponding to the interlayer spacing (2{pi}q{sup {minus}1}{approx}30 {Angstrom} ) ranged from 2 to 60 {mu}s for films from 4 to 50 {mu}m thick. Thus, we have achieved the same time resolution as conventional laser dynamic light scattering, but with 100 times higher spatial resolution. {copyright} {ital 1999} {ital The American Physical Society}

The purpose of this study was to develop a reliable and valid measure of affective disorder in elderly demented patients. The field lacks instruments which are sensitive to detecting depressive signs in severely as well as mildly and moderately demented subjects. Two samples of subjects were chosen for study. The first sample consisted of subjects from six institutions, which were chosen for study from a probability sample of 25 long-term care institutions in New York City. This sample was part of the Cross-National Institutional Study conducted in New York and London (Gurland et al., 1979; Mann et al., 1984). Thirty patients were selected at random within each institution. The second sample consisted of 52 inpatients at Willard Psychiatric Center, a traditional state psychiatric hospital in upstate New York. All subjects had a chart diagnosis of dementia and were 60 years old or older. The mean age of the sample was 82 years and 56% of the subjects were female. The Feeling-Tone Questionnaire, which was developed for these analyses, consists of 16 dichotomous items and 16 5-point Likert ratings of affect. The reliability of this scale using Cronbach's alpha is .91 for the long-term care institutional sample and .90 for the psychiatric hospital sample. Interrater reliability for two raters on ten cases is .99. Test–retest reliability on ten cases with a 1-day to 2-day interval between trials is .81. A short mood scale was developed from the observational data as a validity measure for the Feeling-Tone Questionnaire. Evidence for the validity of the Feeling-Tone Questionnaire is provided.

We show that a normal (single particle) current density ${J}_{x}$ transverse to the ordering wave vector ${2k}_{F}\stackrel{^}{\mathbf{z}}$ of a charge-density wave (CDW) has dramatic effects both above and below the CDW depinning transition. It exponentially (in ${J}_{x}$) enhances CDW correlations and exponentially suppresses the longitudinal depinning field. The intermediate longitudinal $I\ensuremath{-}V$ relation also changes, acquiring a linear regime. We propose a novel ``current-effect transistor'' whose CDW channel is turned on by a transverse current. Our results also have important implications for the recently proposed ``striped phase'' of the high- ${T}_{c}$ superconductors.

In this paper, we present the dynamic layer displacement--layer displacement and the dynamic density-density correlation functions---both for smectic-A systems in the thermodynamic limit, and for real smectic-A films that have finite size, nonzero surface tension acting at the two free surfaces, and nonzero layer sliding viscosity. We also present the results of our soft-x-ray photon correlation spectroscopy experiment, which we have used to directly measure the dynamic density-density correlation function for two different liquid crystals (4O.8 and 7O.7) in the overdamped surface tension restoring force limit of our theory. We used linearized hydrodynamics to first calculate the behavior of smectic-A systems in the thermodynamic limit, and then to calculate the behavior for real, finite size, nonzero surface tension freely suspended liquid crystal films. For the real films, we used the linearized smectic-A hydrodynamic equations and the Gaussian model for the layer fluctuations to compute the set of relaxation times for the displacement field in a finite smectic-A film bounded by two free surfaces. We find that all of the relaxation times have maxima at nonzero values of the transverse wave vector ${\mathbf{q}}_{\ensuremath{\perp}}.$ For thicker films the maxima shift towards ${\mathbf{q}}_{\ensuremath{\perp}}=0$ and grow linearly with the number of smectic layers $N+1.$ For finite N all of the relaxation times tend to zero as ${q}_{\ensuremath{\perp}}\ensuremath{\rightarrow}0,$ except one that attains the finite value ${\ensuremath{\tau}}^{(0)}(0)=(N+1){\ensuremath{\eta}}_{3}d/2\ensuremath{\gamma},$ where ${\ensuremath{\eta}}_{3}$ is the layer sliding viscosity, d is the smectic period, and \ensuremath{\gamma} is the surface tension. We find that the time-dependent scattering intensity integrated over ${\mathbf{q}}_{\ensuremath{\perp}}$ has the simple scaling form ${S(q}_{z},t)\ensuremath{\sim}{(a}_{0}/\ensuremath{\Lambda}{)}^{y(t)},$ where ${a}_{0}$ and \ensuremath{\Lambda} are the molecular size cutoff and the instrument resolution cutoff, respectively, and the time-dependent exponent ${y(t)=(k}_{B}{\mathrm{Tq}}_{z}^{2}/4\ensuremath{\pi}\ensuremath{\gamma})[1\ensuremath{-}\mathrm{exp}(\ensuremath{-}t/{\ensuremath{\tau}}^{(0)}(0))].$ Our results clearly show that the boundary conditions strongly affect the hydrodynamics of real smectics.

We study a model of flocking for a very large system (N=320,000) numerically. We find that in the long wavelength, long time limit, the fluctuations of the velocity and density fields are carried by propagating sound modes, whose dispersion and damping agree quantitatively with the predictions of our previous work using a continuum equation. We find that the sound velocity is anisotropic and characterized by its speed $c$ for propagation perpendicular to the mean velocity $$, $$ itself, and a third velocity $\lambda $, arising explicitly from the lack of Galilean invariance in flocks., Comment: 10 Pages, 5 figures

We study a model for the Nematic--Smectic-A (NA) transition in aerogel, and find that even arbitrarily weak quenched disorder (i.e., low aerogel density) destroys translational (smectic) order. Ignoring elastic anharmonicities, but keeping anharmonic couplings to disorder, leads to the prediction that there is no ``Bragg glass'' phase in this system: it is riddled with dislocation loops induced by the quenched disorder. Orientational (nematic) order is destroyed as well, as is the thermodynamically sharp NA transition, in agreement with recent experimental results., version to appear in Phys. Rev. Lett., minor changes and references added