The correlation between wing kinematics and steering muscle activity in the blowfly Calliphora vicina

Determining how the motor patterns of the nervous system are converted into the mechanical and behavioral output of the body is a central goal in the study of locomotion. In the case of dipteran flight, a population of small steering muscles controls many of the subtle changes in wing kinematics that allow flies to maneuver rapidly. We filmed the wing motion of tethered Calliphora vicina at high speed and simultaneously recorded multi-channel electromyographic signals from some of the prominent steering muscles in order to correlate kinematics with muscle activity. Using this analysis, we found that the timing of each spike in the basalare muscles was strongly correlated with changes in the deviation of the stroke plane during the downstroke. The relationship was non-linear such that the magnitude of the kinematic response to each muscle spike decreased with increasing levels of stroke deviation. This result suggests that downstroke deviation is controlled in part via the mechanical summation of basalare activity. We also found that interactions among the basalares and muscles III2–III4 determine the maximum forward amplitude of the wingstroke. In addition, activity in muscle I1 appears to participate in a wingbeat gearing mechanism, as previously proposed. Using these results, we have been able to correlate changes in wing kinematics with alteration in the spike rate, firing phase and combinatorial activity of identified steering muscles

Neuromuscular control of aerodynamic forces and moments in the blowfly, Calliphora vicina

Flies are among the most agile of flying insects, a capacity that ultimately results from their nervous system's control over steering muscles and aerodynamic forces during flight. In order to investigate the relationships among neuromuscular control, musculo-skeletal mechanics and flight forces, we captured high-speed, three-dimensional wing kinematics of the blowfly, Calliphora vicina, while simultaneously recording electromyogram signals from prominent steering muscles during visually induced turns. We used the quantified kinematics to calculate the translational and rotational components of aerodynamic forces and moments using a theoretical quasi-steady model of force generation, confirmed using a dynamically scaled mechanical model of a Calliphora wing. We identified three independently controlled features of the wingbeat trajectory – downstroke deviation, dorsal amplitude and mode. Modulation of each of these kinematic features corresponded to both activity in a distinct steering muscle group and a distinct manipulation of the aerodynamic force vector. This functional specificity resulted from the independent control of downstroke and upstroke forces rather than the independent control of separate aerodynamic mechanisms. The predicted contributions of each kinematic feature to body lift, thrust, roll, yaw and pitch are discussed

Does Monitoring Decrease Work Effort ? The Complementarity Between Agency and Crowding-Out Theorie

Agency theory assumes that tighter monitoring by the principal should motivate the agent to raise his effort level whereas the “crowding-out” literature suggests that it may reduce the overall work effort. These two assertions are not necessarily contradictory provided that the nature of the employment relationship is taken into account (Frey, 1993). Based upon a real-task laboratory experiment, our results show that principals are not trustful enough to refrain from monitoring the agents, and most of the agents react to the disciplining effect of monitoring. However we find also some evidence that intrinsic motivation is crowded out when monitoring is above a certain threshold. We identify that both interpersonal principal/agent links and concerns for the distribution of output payoff are important for the emergence of this crowding out effect.crowding-out; monitoring; motivation; principal-agent theory; real effort experiments

Does Monitoring Decrease Work Effort? The Complementarity Between Agency and Crowding-Out Theories

Agency theory assumes that tighter monitoring by the principal should motivate the agent to raise his effort level. In contrast, the “crowding-out” literature suggests that tighter monitoring may reduce the overall work effort. These two assertions are not necessarily contradictory provided that the nature of the employment relationship is taken into account (Frey 1993). This paper reports on the results of a real-effort laboratory experiment designed to test the relative importance of the disciplining effect and the crowding-out effect of monitoring. We find no strong support for the crowding-out hypothesis and we show that the disciplining effect of monitoring dominates in abstract one-shot relationships as well as in somewhat more interpersonal multi-shot relationships. Principals are not trustful enough to refrain from using the monitoring opportunity and most agents react to a decrease in the monitoring intensity by decreasing their effort.

Interprofessional education for community mental health : changing attitudes and developing skills

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The Peter Principle: An Experiment

The Peter Principle states that, after a promotion, the observed output of promoted employees tends to fall. Lazear (2004) models this principle as resulting from a regression to the mean of the transitory component of ability. Our experiment reproduces this model in the laboratory by means of various treatments in which we alter the variance of the transitory ability. We also compare the efficiency of an exogenous promotion standard with a treatment where subjects self-select their task. Our evidence confirms the Peter Principle when the variance of the transitory ability is large. In most cases, the efficiency of job allocation is higher when using a promotion rule than when employees are allowed to self-select their task. This is likely due to subjects’ bias regarding their transitory ability. Naïve thinking, more than optimism/pessimism bias, may explain why subjects do not distort their effort prior to promotion, contrary to Lazear’s (2004) prediction. Key Words: Promotion, Peter Principle, Sorting, Experiment

The Peter Principle: An Experiment

Working Paper GATE 2007-28International audienceThe Peter Principle states that, after a promotion, the observed output of promoted employees tends to fall. Lazear (2004) models this principle as resulting from a regression to the mean of the transitory component of ability. Our experiment reproduces this model in the laboratory by means of various treatments in which we alter the variance of the transitory ability. We also compare the efficiency of an exogenous promotion standard with a treatment where subjects self-select their task. Our evidence confirms the Peter Principle when the variance of the transitory ability is large. In most cases, the efficiency of job allocation is higher when using a promotion rule than when employees are allowed to self-select their task. This is likely due to subjects' bias regarding their transitory ability. Naïve thinking, more than optimism/pessimism bias, may explain why subjects do not distort their effort prior to promotion, contrary to Lazear's (2004) prediction.Le Principe de Peter établit qu'après une promotion, la production des salariés promus tend à diminuer. Lazear (2004) offre un modèle théorique selon lequel ce principe résulte d'un phénomène de régression à la moyenne de la composante temporaire de l'habileté. Notre expérience reproduit ce modèle en laboratoire à l'aide de plusieurs traitements dans lesquels est modifiée la variance de l'habileté transitoire. Nous comparons également l'efficience d'une règle exogène de promotion avec un traitement dans lequel les sujets peuvent choisir leur tâche. Nos résultats confirment l'existence du Principe de Peter lorsque la variance de l'habileté transitoire est forte. Dans la plupart des cas, l'efficience allocative d'une règle de promotion est supérieure à celle obtenue lorsque les salariés choisissent eux-mêmes leur tâche. Ceci résulte probablement d'un biais de perception relatif à l'habileté transitoire. L'absence de raisonnement stratégique, plutôt qu'un biais d'optimisme/pessimisme, explique pourquoi les sujets ne distordent pas leur effort préalablement à la décision de promotion, contrairement à la prédiction de Lazear (2004)

Norm Enforcement in Social Dilemmas. An Experiment with Police Commissioners

International audienc

Planning for tomorrow whilst living for today: the views of people with dementia and their families on Advance Care Planning

Background: Advance care planning (ACP) is increasingly prominent in many countries; however, the evidence base for its acceptability and effectiveness is limited especially in conditions where cognition is impaired, as in dementia. Method: This qualitative study used semi-structured interviews with people with mild to moderate dementia (n = 17) and family carers (n = 29) to investigate their views about planning for their future generally and ACP specifically. Results: People with dementia and their families make a number of plans for the future. Most people undertook practical, personal, financial, and legal planning. However participants did not make formal advance care plans with the exception of appointing someone to manage their financial affairs. Five barriers to undertaking ACP were identified: lack of knowledge and awareness, difficulty in finding the right time, a preference for informal plans over written documentation, constraints on choice around future care, and lack of support to make choices about future healthcare. Conclusions: Health and social care professionals can build on people's preferences for informal planning by exploring the assumptions underlying them, providing information about the possible illness trajectory and discussing the options of care available. Health and social care professionals also have a role to play in highlighting the aspects of ACP which seem to be most relevant to the wishes and aspirations of people with dementia