Lepton Acceleration in Pulsar Wind Nebulae

Pulsar Wind Nebulae (PWNe) act as calorimeters for the relativistic pair winds emanating from within the pulsar light cylinder. Their radiative dissipation in various wavebands is significantly different from that of their pulsar central engines: the broadband spectra of PWNe possess characteristics distinct from those of pulsars, thereby demanding a site of lepton acceleration remote from the pulsar magnetosphere. A principal candidate for this locale is the pulsar wind termination shock, a putatively highly-oblique, ultra-relativistic MHD discontinuity. This paper summarizes key characteristics of relativistic shock acceleration germane to PWNe, using predominantly Monte Carlo simulation techniques that compare well with semi-analytic solutions of the diffusion-convection equation. The array of potential spectral indices for the pair distribution function is explored, defining how these depend critically on the parameters of the turbulent plasma in the shock environs. Injection efficiencies into the acceleration process are also addressed. Informative constraints on the frequency of particle scattering and the level of field turbulence are identified using the multiwavelength observations of selected PWNe. These suggest that the termination shock can be comfortably invoked as a principal injector of energetic leptons into PWNe without resorting to unrealistic properties for the shock layer turbulence or MHD structure.Comment: 19 pages, 5 figures, invited review to appear in Proc. of the inaugural ICREA Workshop on "The High-Energy Emission from Pulsars and their Systems" (2010), eds. N. Rea and D. Torres, (Springer Astrophysics and Space Science series

Acute physical exercise can influence the accuracy of metacognitive judgments

Acute exercise generally benefits memory but little research has examined how exercise affects metacognition (knowledge of memory performance). We show that a single bout of exercise can influence metacognition in paired-associate learning. Participants completed 30- min of moderate-intensity exercise before or after studying a series of word pairs (cloudivory), and completed cued-recall (cloud-?; Experiments 1 & 2) and recognition memory tests (cloud-? spoon; ivory; drill; choir; Experiment 2). Participants made judgments of learning prior to cued-recall tests (JOLs; predicted likelihood of recalling the second word of each pair when shown the first) and feeling-of-knowing judgments prior to recognition tests (FOK; predicted likelihood of recognizing the second word from four alternatives). Compared to noexercise control conditions, exercise before encoding enhanced cued-recall in Experiment 1 but not Experiment 2 and did not affect recognition. Exercise after encoding did not influence memory. In conditions where exercise did not benefit memory, it increased JOLs and FOK judgments relative to accuracy (Experiments 1 & 2) and impaired the relative accuracy of JOLs (ability to distinguish remembered from non-remembered items; Experiment 2). Acute exercise seems to signal likely remembering; this has implications for understanding the effects of exercise on metacognition, and for incorporating exercise into study routines

Parkinson's Disease: Basic Pathomechanisms and a Clinical Overview

PD is a common and a debilitating degenerative movement disorder. The number of patients is increasing worldwide and as yet there is no cure for the disease. The majority of existing treatments target motor symptom control. Over the last two decades the impact of the genetic contribution to PD has been appreciated. Significant discoveries have been made, which have advanced our understanding of the pathophysiological and molecular basis of PD. In this chapter we outline current knowledge of the clinical aspects of PD and the basic mechanistic understanding

Are you sure about that? Eliciting confidence ratings may influence performance on Raven's progressive matrices

Confidence ratings (CR) have often been integrated into reasoning and intelligence tasks as a means for assessing meta-reasoning processes. Although it is often assumed that eliciting these judgements throughout reasoning tasks has no effect on the underlying performance outcomes, this is yet to be established empirically. The current study examines whether eliciting CR from participants during a fluid-reasoning task influences their performance and how this effect is moderated by their initial self-confidence in their own reasoning abilities. In a first experiment, we found that participants performing CR during Raven's Progressive Matrices significantly outperformed a control group who did not provide ratings. Additionally, a second experiment demonstrated that CR only facilitated performance in participants who have a high level of initial self-confidence in their reasoning ability, whereas they were detrimental to participants low in self-confidence

Are you sure about that? Eliciting confidence ratings may influence performance on Raven's progressive matrices

Confidence ratings (CR) have often been integrated into reasoning and intelligence tasks as a means for assessing meta-reasoning processes. Although it is often assumed that eliciting these judgements throughout reasoning tasks has no effect on the underlying performance outcomes, this is yet to be established empirically. The current study examines whether eliciting CR from participants during a fluid-reasoning task influences their performance and how this effect is moderated by their initial self-confidence in their own reasoning abilities. In a first experiment, we found that participants performing CR during Raven's Progressive Matrices significantly outperformed a control group who did not provide ratings. Additionally, a second experiment demonstrated that CR only facilitated performance in participants who have a high level of initial self-confidence in their reasoning ability, whereas they were detrimental to participants low in self-confidence

Reactivity to confidence ratings in older individuals performing the latin square task

Confidence ratings (CR) are often used to evaluate the metacognitive processes that occur during reasoning and problem solving. Typically CR are elicited with the assumption that they do not affect participants’ underlying cognitive processes. However, recent evidence suggests that eliciting CR can cause changes in cognitive performance. What is not yet clear, are the metacognitive pathways by which CR affect overall performance in older individuals. In order to better understand the mechanisms driving reactivity to CR, we evaluated the impact of eliciting CR in an older sample (N = 89) on two aspects of the metacognitive framework - monitoring and control. Participants first rated their prospective confidence before performing the Latin Square Task either with or without confidence ratings. Participants subsequently self-appraised their performance. We found evidence that eliciting CR leads to poorer metacognitive monitoring. In addition, we found that participants with high initial prospective self-confidence who perform CR adopt a more immediate performance-orientated control strategy, which improves short-term performance but has no effect on overall performance in a timed Latin Square Task

Reactivity to confidence ratings in older individuals performing the latin square task

Confidence ratings (CR) are often used to evaluate the metacognitive processes that occur during reasoning and problem solving. Typically CR are elicited with the assumption that they do not affect participants’ underlying cognitive processes. However, recent evidence suggests that eliciting CR can cause changes in cognitive performance. What is not yet clear, are the metacognitive pathways by which CR affect overall performance in older individuals. In order to better understand the mechanisms driving reactivity to CR, we evaluated the impact of eliciting CR in an older sample (N = 89) on two aspects of the metacognitive framework - monitoring and control. Participants first rated their prospective confidence before performing the Latin Square Task either with or without confidence ratings. Participants subsequently self-appraised their performance. We found evidence that eliciting CR leads to poorer metacognitive monitoring. In addition, we found that participants with high initial prospective self-confidence who perform CR adopt a more immediate performance-orientated control strategy, which improves short-term performance but has no effect on overall performance in a timed Latin Square Task

The impact of peer assessment on academic performance: a meta-analysis of control group studies

Peer assessment has been the subject of considerable research interest over the last three decades, with numerous educational researchers advocating for the integration of peer assessment into schools and instructional practice. Research synthesis in this area has, however, largely relied on narrative reviews to evaluate the efficacy of peer assessment. Here, we present a meta-analysis (54 studies, k = 141) of experimental and quasiexperimental studies that evaluated the effect of peer assessment on academic performance in primary, secondary, or tertiary students across subjects and domains. An overall small to medium effect of peer assessment on academic performance was found (g = 0.31, p < .001). The results suggest that peer assessment improves academic performance compared with no assessment (g = 0.31, p = .004) and teacher assessment (g = 0.28, p = .007), but was not significantly different in its effect from self-assessment (g = 0.23, p = .209). Additionally, meta-regressions examined the moderating effects of several feedback and educational characteristics (e.g., online vs offline, frequency, education level). Results suggested that the effectiveness of peer assessment was remarkably robust across a wide range of contexts. These findings provide support for peer assessment as a formative practice and suggest several implications for the implementation of peer assessment into the classroom