191 resultados para Action Potential


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Despite the increasing importance of, and interest in, documenting the impact of environmental education programs on students' learning for sustainability, few tools are currently available to measure young students' environmental learning across all the dimensions of knowledge, skills, attitudes and behaviours. This paper reports on the development of such a tool, using an iterative action research process with 134 students, aged six to eleven, attending programs at an Environmental Education Centre in Queensland. The resulting instrument, the Environmental Learning Outcomes Survey (ELOS) incorporates observations of students' engagement in learning processes as well as measuring learning outcomes, and allows both of these aspects to be linked to particular components of the environmental education program. Test data using the instrument are reported to illustrate its potential usefulness. It is envisaged that the refined instrument will enable researchers to measure student environmental learning in the field, investigate environmental education program impacts and identify aspects of programs that are most effective in facilitating student learning. [Author abstract]

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Harmful algal blooms (HABs) have increased in abundance and severity in recent decades. Whereas the implications for human impacts and intoxication resulting from blooms have been extensively studied, the ecological implications of these microalgae are less well understood. Many HAB species produce biologically active, secondary metabolites and the fate of these toxins through the foodweb is generally not well understood unless it culminates in extensive fish mortalities or human poisonings. This review focusses on one HAB species, the cyanobacterium Lyngbya majuscula, and presents a hypothetical role for its involvement in fibro-papillornatosis (FP), a neoplastic disease of marine turtles. FP is expressed as benign tumours that grow both internally and externally on marine turtles, preventing vision, movement and organ function. The aetiology of FP is currently not conclusively understood, but virus material has been associated with tumours and previous studies have suggested a role for naturally produced tumour promoters. In this review, we present a hypothesis regarding the involvement of L. majuscula in FP, either through direct intoxication and action of tumour-promoting compounds or indirectly by causing seagrass loss and compromised immune function, thus leaving the turtles more susceptible to disease.

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Highly selective N-type voltage-gated calcium (Ca-V) channel inhibitors from cone snail venom (the omega-conotoxins) have emerged as a new class of therapeutics for the treatment of chronic and neuropathic pain. Earlier in 2005, Prialt ( Elan) or synthetic omega-conotoxin MVIIA, was the first omega-conotoxin to be approved by Food and Drug Administration for human use. This review compares the action of three omega-conotoxins, GVIA, MVIIA and CVID, describing their structure-activity relationships and potential as leads for the design of improved N-type therapeutics that are more useful in the treatment of chronic pain.

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Treatment of schizophrenia with olanzapine and other atypical antipsychotic agents is associated with insulin resistance and diabetes mellitus. The mechanism for this is not understood. Adiponectin is an insulin-sensitizing cytokine secreted by adipocytes. It is present in serum in multimers of varying size. Trimers and hexamers are referred to as low molecular weight (LMW) adiponectin. Larger multimers (12-, 18-, and 24-mers) have been designated high molecular weight (HMW) adiponectin and seem responsible for the insulin-sensitizing action of this adipokine. The aim of this study was to examine total adiponectin and LMW and HMW multimers in serum from patients with schizophrenia treated with either olanzapine (n = 9) or other typical antipsychotics (n = 9) and compare results with 16 healthy sex-, body mass index-, and age-matched controls. The effects of olanzapine on adiponectin protein expression and secretion in in vitro-differentiated primary human adipocytes were also examined. Patients receiving olanzapine had significantly lower total serum adiponectin as compared with those on conventional treatment and controls (5.23 +/- 1.53 ng/mL vs. 8.20 +/- 3.77 ng/mL and 8.78 +/- 3.8 ng/mL; P < 0.05 and P < 0.01, respectively). The HMW adiponectin was also reduced in patients on olanzapine as compared with the disease and healthy control groups (1.67 +/- 0.96 ng/mL vs. 3.87 +/- 2.69 ng/mL and 4.07 +/- 3.2 ng/mL; P < 0.05 for both). The LMW adiponectin was not different between patient groups (P = 0.15) but lower in patients on olanzapine as compared with controls (3.56 +/- 10.85 ng/mL vs. 4.70 +/- 1.4 ng/mL; P < 0.05). In vitro, short duration (up to 7 days) olanzapine exposure had no effect on total adiponectin expression or multimer composition of secreted protein. In summary, this study demonstrates a correlation between olanzapine treatment and reduced serum adiponectin, particularly HMW multimers. This may not be a direct effect of olanzapine on adipocyte expression or secretion of adiponectin. These observations provide insights into possible mechanisms for the association between olanzapine treatment and insulin resistance.

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Working memory is an essential component of wide-ranging cognitive functions. It is a complex genetic trait probably influenced by numerous genes that individually have only a small influence. These genes may have an amplified influence on phenotypes closer to the gene action. In this study, event-related potential (ERP) phenotypes recorded during a working-memory task were collected from 656 adolescents from 299 families for whom genotypes were available. Univariate linkage analyses using the MERLIN variance-components method were conducted on slow wave phenotypes recorded at multiple sites while participants were required to remember the location of a target. Suggestive linkage (LOD > 2.2) was found on chromosomes 4, 5, 6, 10, 17, and 20. After correcting for multiple testing, suggestive linkage remained on chromosome 10. Empirical thresholds were computed for the most promising phenotypes. Those on chromosome 10 remained suggestive. A number of genes reported to regulate neural differentiation and function (i.e. NRP1, ANK3, and CHAT) were found under these linkage peaks and may influence the levels of neural activity occurring in individuals participating in a spatial working-memory task.

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This paper identifies research priorities in evaluating the ways in which "genomic medicine"-the use of genetic information to prevent and treat disease-may reduce tobacco-related harm by: (1) assisting more smokers to quit; (2) preventing non-smokers from beginning to smoke tobacco; and (3) reducing the harm caused by tobacco smoking. The method proposed to achieve the first aim is pharmacogenetics", the use of genetic information to optimise the selection of smoking-cessation programmes by screening smokers for polymorphisms that predict responses to different methods of smoking cessation. This method competes with the development of more effective forms of smoking cessation that involve vaccinating smokers against the effects of nicotine and using new pharmaceuticals (such as cannabinoid antagonists and nicotine agonists). The second and third aims are more speculative. They include: screening the population for genetic susceptibility to nicotine dependence and intervening (eg, by vaccinating children and adolescents against the effects of nicotine) to prevent smoking uptake, and screening the population for genetic susceptibility to tobacco-related diseases. A framework is described for future research on these policy options. This includes: epidemiological modelling and economic evaluation to specify the conditions under which these strategies are cost-effective; and social psychological research into the effect of providing genetic information on smokers' preparedness to quit, and the general views of the public on tobacco smoking.

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Results of two experiments are reported that examined how people respond to rectangular targets of different sizes in simple hitting tasks. If a target moves in a straight line and a person is constrained to move along a linear track oriented perpendicular to the targetrsquos motion, then the length of the target along its direction of motion constrains the temporal accuracy and precision required to make the interception. The dimensions of the target perpendicular to its direction of motion place no constraints on performance in such a task. In contrast, if the person is not constrained to move along a straight track, the targetrsquos dimensions may constrain the spatial as well as the temporal accuracy and precision. The experiments reported here examined how people responded to targets of different vertical extent (height): the task was to strike targets that moved along a straight, horizontal path. In experiment 1 participants were constrained to move along a horizontal linear track to strike targets and so target height did not constrain performance. Target height, length and speed were co-varied. Movement time (MT) was unaffected by target height but was systematically affected by length (briefer movements to smaller targets) and speed (briefer movements to faster targets). Peak movement speed (Vmax) was influenced by all three independent variables: participants struck shorter, narrower and faster targets harder. In experiment 2, participants were constrained to move in a vertical plane normal to the targetrsquos direction of motion. In this task target height constrains the spatial accuracy required to contact the target. Three groups of eight participants struck targets of different height but of constant length and speed, hence constant temporal accuracy demand (different for each group, one group struck stationary targets = no temporal accuracy demand). On average, participants showed little or no systematic response to changes in spatial accuracy demand on any dependent measure (MT, Vmax, spatial variable error). The results are interpreted in relation to previous results on movements aimed at stationary targets in the absence of visual feedback.

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Different interceptive tasks and modes of interception (hitting or capturing) do not necessarily involve similar control processes. Control based on preprogramming of movement parameters is possible for actions with brief movement times but is now widely rejected; continuous perceptuomotor control models are preferred for all types of interception. The rejection of preprogrammed control and acceptance of continuous control is evaluated for the timing of rapidly executed, manual hitting actions. It is shown that a preprogrammed control model is capable of providing a convincing account of observed behavior patterns that avoids many of the arguments that have been raised against it. Prominent continuous perceptual control models are analyzed within a common framework and are shown to be interpretable as feedback control strategies. Although these models can explain observations of on-line adjustments to movement, they offer only post hoc explanations for observed behavior patterns in hitting tasks and are not directly supported by data. It is proposed that rapid manual hitting tasks make up a class of interceptions for which a preprogrammed strategy is adopted-a strategy that minimizes the role of visual feedback. Such a strategy is effective when the task demands a high degree of temporal accuracy.

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A spotted fever-like rickettsia was identified in a Hemaphysalis tick by polymerase chain reaction (PCR) amplification and sequencing of the 16S rDNA, ompA, and ompB genes. A comparison of these nucleotide sequences with those of other spotted fever group (SFG) rickettsiae revealed that the Hemaphysalis tick rickettsia was distinct from other previously reported strains. Phylogenetic analysis based on both ompA and ompB also indicates that the strain’s closest relatives are the agents of Thai tick typhus (Rickettsia honei strain TT-118) and Flinders Island spotted fever (R. honei). This study represents the first report of an R. honei-like agent from a Hemaphysalis tick in Australia and of a spotted fever group rickettsia from Cape York Peninsula, Queensland.

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A virulent strain of Wolbachia has recently been identified in Drosophila that drastically reduces adult lifespan. It has been proposed that this phenotype might be introduced into insect disease vector populations to reduce pathogen transmission. Here we model the requirements for spread of such an agent and the associated reduction in disease transmission. First, a simulation of mosquito population age structure was used to describe the age distribution of mosquitoes transmitting dengue virus. Second, given varying levels of cytoplasmic incompatibility and fecundity effect, the maximum possible longevity reduction that would allow Wolbachia to invade was obtained. Finally, the two models were combined to estimate the reduction in disease transmission according to different introduction frequencies. With strong CI and limited effect of fecundity, an introduction of Wolbachia with an initial frequency of 0.4 could result in a 60–80% reduction of transmitting mosquitoes. Greater reductions are possible at higher initial release rates.

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Action systems are a construct for reasoning about concurrent, reactive systems, in which concurrent behaviour is described by interleaving atomic actions. Sere and Troubitsyna have proposed an extension to action systems in which actions may be expressed and composed using discrete probabilistic choice as well as demonic nondeterministic choice. In this paper we develop a trace-based semantics for probabilistic action systems. This semantics provides a simple theoretical base on which practical refinement rules for probabilistic action systems may be justified.

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Globalisation, increasing complexity, and the need to address triple-bottom line sustainability has seen the proliferation of Learning Organisations (LO) who, by definition, have the capacity to anticipate environmental changes and economic opportunities and adapt accordingly. Such organisations use system dynamics modelling (SDM) for both strategic planning and the promotion of organisational learning. Although SDM has been applied in the context of tourism destination management for predictive reasons, the current literature does not analyse or recognise how this could be used as a foundation for an LO. This study introduces the concept of the Learning Tourism Destinations (LTD) and discusses, on the basis of a review of 6 case studies, the potential of SDM as a tool for the implementation and enhancement of collective learning processes. The results reveal that SDM is capable of promoting communication between stakeholders and stimulating organisational learning. It is suggested that the LTD approach be further utilised and explored.

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