Publication bias (PB) makes the resources for meta-analysis (M-A) unreliable in the sense of completion and accuracy, so to investigate, identify and correct PB is a very important issue in M-A. The current study proposed an empirical comparison in both detection and correcting PB, using a Monte Carlo study. Conditions to be manipulated include the number of primary studies, number of missing studies and true effect size. RANNOR in SAS will be used to generate normally distributed random variables and, for each condition, 10,000 M-As will be simulated. Type I error rates are to be calculated for the conditions with no PB and powers were estimated for the conditions with PB and adequate type I error control. Finally, a demonstration of how M-A can and should be used as a part of program evaluations was given. / text

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Internkommunikation är en konstant del i varje organisation eftersom alla människor på något sätt kommunicerar. Forskning har visat att internkommunikation på många sätt kan öka en organisationens lönsamhet, förutsatt att den är väl fungerande och inkluderar alla anställda. Tydliga instruktioner och direktiv för alla delaktiga parter är två grundförutsättningar. Dessa anvisningar och förtydliganden kallas meta-kommunikation. Mitt syfte har varit att undersöka hur sådan kommunikation hanteras i en platt organisationsstruktur utan tydliga chefspositioner, vilket leder till oklarhet gällande vem som ska ge dessa direktiv.   En instrumentell fallstudie där syftet är att granska en specifik händelse eller organisation utfördes med bostadsbolaget KBAB som undersökningsobjekt. För att kunna uppfylla syftet och svara på frågeställningarna var jag intresserad av att få ta del av de anställdas tankar och uppfattningar, vilket gjorde att den metod som lämpade sig bäst och också utfördes var personliga intervjuer.   Resultatet visar att meta-kommunikation i en platt organisationsstruktur ter sig annorlunda än i en hierarkisk. Den är inbyggd i varje anställds tjänst på så sätt att den faller på varje individs eget ansvar. Arbetssättet kräver mycket samarbete medarbetarna emellan, och aktivt deltagande i internkommunikationen är därför en förutsättning för att arbetet i organisationen ska fungera. De hinder som organisationsstrukturen visade sig skapa för meta-kommunikationen var tidsbrist, en otydlig överblick över de anställdas arbete och särskilda krav på varje individs personlighet. Ytterligare en slutsats som gick att dra av resultatet var att den platta organisationsstrukturen ur många aspekter gjorde de anställda medvetna. Det här visade sig särskilt i en medvetenhet om organisationens arbetssätt och i insikten om vilken viktig roll internkommunikationen hade i detta.

Mindfulness-Based Therapies (MBT) are a current technology within the cognitive behavioural tradition, which can be grouped according to whether mindfulness is a major or a minor component. A mindful approach to psychological difficulties attempts to change the relationship with unwanted inner experience. The model suggests this may help reduce affective symptomatology. There has been a considerable growth of interest in these therapies with an accompanying increase in the evidence base. A number of reviews have been conducted however they have not comprehensively appraised these therapies. The primary aim of my study was to contribute to ongoing research determining the effectiveness of MBT for the treatment of affective symptomatology. Depending on these results, a secondary aim of the study was to make recommendations for the use of MBT in clinical practice. Methods I conducted a meta-analysis which looked separately at therapies considered to have mindfulness as a major component; therapies considered to have mindfulness as a minor component; and a comparison of these two groups. Of the 598 unique citations identified in the literature, 113 were assessed for eligibility and 40 included in the pool of studies for the meta-analysis. Results For the major component therapies, there was a significant mean reduction score in depressive symptomatology as measured by the BDI of 8.73 points (k = 11; 95% CI = 6.61, 10.86). Evidence of effectiveness was also found for the minor component therapies (k = 8) in reducing anxiety symptomatology with a significant standardised mean difference of 1.24 (95% CI = 0.81, 2.10). Discussion I found evidence for the effectiveness of mindfulness-based therapies in reducing levels of depression or anxiety mainly in patients diagnosed with depressive or anxiety disorders. The robustness of these findings is discussed alongside the implications for research and practice within the context of the current literature.

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Ischaemic stroke is responsible for substantial death and disability and creates a huge financial burden for healthcare budgets worldwide. At present there are few effective treatments for acute stroke and these are urgently required. Increased understanding of the ischaemic cascade has generated interest in neuroprotection for focal cerebral ischaemia. However, treatment effects observed in of over 500 interventions in animal models have yet to be translated to the clinic. Systematic review and meta-analysis allows unbiased identification of all relevant data for a given intervention, gives a clearer view of its true efficacy and the limitations to its therapeutic potential. Understanding the reasons for this bench-to-bedside failure and providing quantitative explanations may help to address these discrepancies. Random effects weighted mean difference meta-analysis of six interventions (tirilazad, tPA, NXY-059, Hypothermia, Piracetam and IL1-RA) reported study quality to be consistently low. In some instances, potential sources of bias were associated with overestimations of efficacy. Likewise, clinical trials have tested interventions in conditions where efficacy was not observed in animals. Cumulative meta-analysis suggests that for tPA the estimate of efficacy is stable after the inclusion of data from 1500 animals; hypothermia and FK506 are the only other interventions to have been tested in at least 1500 animals. Meta-regression suggests biological rather methodical factors are better predictors of outcome; a major limitation of these data is the impact of publication bias, and this work suggests effect sizes from met-analyses are inflated by about 31% because 16% of studies remain unpublished. The systematic review and meta-analysis of hypothermia was used to plan experiments investigating the possible impact of pethidine, a drug used to prevent shivering. This in vivo experiment, in which potential sources of bias were minimised, suggests that pethidine does not influence the observed efficacy of hypothermia in an animal model of ischaemic stroke. This thesis reports that animal studies of ischaemic stroke are often not conducted with sufficient rigour. Both minimising potential sources of bias in individual experiments and using meta-analysis to summarise data from a number of experiments may be helpful in improving the translation of neuroprotective efficacy in ischaemic stroke.

This thesis is about what happens in the brain when people switch between tasks. Each task requires a particular assembly of cognitive processes, an orientation of attention and set of rules relating action to input — a "task-set". The research reported used a task-cueing paradigm to study preparatory control of task-set. On each trial a stimulus (a coloured shape) was preceded by a verbal task-cue specifying which task to do (judge the shape or the colour of the stimulus). Reaction time and error rate increase on trials when the task changes relative to trials on which it does not. When the cue stimulus interval (CSI) is increased, this "switch cost" is reduced, indexing a process of task-set reconfiguration in which top-down control is employed to reconfigure the task-set parameters. Effective reconfiguration may also be indicated by a reduction in the "response congruence effect" — poorer performance on stimuli mapped to different responses for the two tasks than for stimuli mapped to the same response. I present six experiments using transcranial magnetic stimulation (TMS), a technique for interfering briefly and harmlessly with neuronal activity in a small region of cortex, to address the question of which brain regions contribute to anticipatory control of task-set as indexed by these behavioural measures. To help guide the selection of candidate brain regions, I first present a review and meta-analysis of neuroimaging studies of task-switching in the literature. Many fMRI studies, comparing brain activation on task-switch and -repeat trials have been published. Some have also tried to isolate activations related specifically to pro-active control of task-set. The activations reported are quite inconsistent over studies. I used a quantitative meta-analysis technique to identify which brain regions are most consistently found by studies reporting switch minus repeat contrasts and which may be specifically important for preparation on switch trials. The experiments examined the effect of stimulating several regions during the long cue-stimulus interval of a task-cueing paradigm, relative to control conditions. A first pair of experiments suggests an important role in proactive task-set control for two regions in dorsal medial frontal cortex, the supplementary motor area (SMA) and an area known as pre-SMA, though the former region appeared to contribute to reducing the switch cost while the latter appeared to reduce the effects of response congruence. In a further three experiments, I examined the role of the right intra-parietal sulcus (rIPS); this appears to play a crucial role in preparation for a task-switch but not post-stimulus task-set reconfiguration. In a final experiment, I used TMS guided by fMRI activations in the same participants to study the effects of stimulation over the left inferior frontal junction (IFJ). The results indicate that a region just anterior to the left IFJ is specifically important for preparing for a switch trial. I discuss the roles that may be played by these three regions in task-set control.