Cardiovascular actions of trout urotensin II in the conscious trout, Oncorhynchus mykiss

The central and peripheral cardiovascular effects of synthetic trout urotensin II (UII) were investigated in the conscious rainbow trout. Intracerebroventricular injection of 50 pmol UII produced a slight (3%) but significant (P < 0.05) increase in heart rate but had no effect on mean arterial blood pressure. Injection of 500 pmol UII icy produced a significant (P < 0.05) rise (8%) in blood pressure with no change in heart rate. In contrast to the weak presser effect of centrally administered UII, intra-arterial injection of UII produced a dose-dependent increase in arterial blood pressure and decrease in heart rate with significant (P < 0.05) effects on both parameters observed at a dose of 25 pmol. Higher doses of the peptide produced a sustained decrease in cardiac output that accompanied the bradycardia and rise in arterial blood pressure. The UII-induced bradycardia, but not the increase in pressure, was abolished by pretreatment with phentolamine. Trout UII produced a sustained and dose-dependent contraction of isolated vascular rings prepared from trout efferent branchial [-log 50% of the concentration producing maximal contraction (pD(2)) = 8.30] and celiacomesenteric (pD(2) = 8.22) arteries but was without effects on vascular rings from the anterior cardinal vein. The data indicate that the presser effect of UII in trout is mediated predominantly, if not exclusively, by an increase in systemic vascular resistance. The UII-induced hypertensive response does not seem to involve release of catecholamines, but the bradycardia may arise from adrenergic-mediated activation of cardioinhibitory baroreflexes.

Modelling the control of interceptive actions

In recent years, several phenomenological dynamical models have been formulated that describe how perceptual variables are incorporated in the control of motor variables. We call these short-route models as they do not address how perception-action patterns might be constrained by the dynamical properties of the sensory, neural and musculoskeletal subsystems of the human action system. As an alternative, we advocate a long-route modelling approach in which the dynamics of these subsystems are explicitly addressed and integrated to reproduce interceptive actions. The approach is exemplified through a discussion of a recently developed model for interceptive actions consisting of a neural network architecture for the online generation of motor outflow commands, based on time-to-contact information and information about the relative positions and velocities of hand and ball. This network is shown to be consistent with both behavioural and neurophysiological data. Finally, some problems are discussed with regard to the question of how the motor outflow commands (i.e. the intended movement) might be modulated in view of the musculoskeletal dynamics.

Prospective control of manual interceptive actions:comparative simulations of extant and new model constructs

Two prospective controllers of hand movements in catching-both based on required velocity control-were simulated. Under certain conditions, this required velocity control led to overshoots of the future interception point. These overshoots were absent in pertinent experiments. To remedy this shortcoming, the required velocity model was reformulated in terms of a neural network, the Vector Integration To Endpoint model, to create a Required Velocity Integration To Endpoint model. Addition of a parallel relative velocity channel, resulting in the Relative and Required Velocity Integration To Endpoint model, provided a better account for the experimentally observed kinematics than the existing, purely behavioral models. Simulations of reaching to intercept decelerating and accelerating objects in the presence of background motion were performed to make distinct predictions for future experiments.

Student teachers' experiences of initial teacher preparation in England:Core themes and variation

Drawing on data generated via large-scale survey and in-depth interview methods, this article reports findings which show that being a student teacher in early-twenty-first-century England is a demanding personal experience which requires considerable engagement and commitment in the face of built-in challenges and risks, and which engenders, for many, highly charged affective responses. Student teachers are centrally concerned during this time with their (changing) identities, their relationships with others and the relevance of course provision. Findings also indicate that, in some respects, student teachers’ accounts of their experiences are systematically differentiated according to a number of factors, notably the initial teacher preparation route being followed, their age, and their prior conceptions and expectations of teaching and of learning to teach. These findings are situated in the broader literature on teacher development and some implications for teacher educators are discussed. © 2008 Taylor & Francis

Language Teacher Education in Ireland, North and South

The European Union considers modern languages among the basic skills or key competencies required by all its citizens and is concerned to promote excellence in the teaching and learning of languages as well as greater diversity in the range of languages available to learners in the Member States, as witnessed by the recent European Commission Action Plan, Promoting Language Learning and Linguistic Diversity: An Action Plan 2004-2006. This consideration, the changing socio-cultural demography of Ireland, the need for more joined-up thinking in the context of language teaching in schools, and in the context of language teacher education in particular, form the back-drop to the paper. Among the challenges facing modern/world languages’ education in Ireland identified in the paper are, lack of a languages’ policy, lack of a languages’ strategy, and lack of an integrated language curriculum and by implication, a whole school approach to language teaching and learning. The paper refers to positive signs that are occurring in this context as well, e.g. official recognition to Irish as a working language in the European Union and in the Official Languages Act in Ireland (2003). The paper reports on the recent first ever all Ireland cross-border conference in the context of language teacher education. It outlines the background, aims, and content of the conference that includes findings from a study about the impact of autonomous language teaching and learning supported by the European Language Portfolio in the context of post-primary language teacher education in Ireland. The paper shows data from the first ever survey on language teacher education provision, policy and practice across colleges in Ireland, North and South. Initial teacher education is on the cusp of change. This paper highlights several key issues facing language teacher education. This paper has implications for Irish as well as international readers, and is aimed at supporting all those who want to bring about improvement in this important area.