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Random Changes (random + change)
Selected AbstractsAge differences in learning from text: Evidence for functionally distinct text processing systemsAPPLIED COGNITIVE PSYCHOLOGY, Issue 4 2009Matthew C. Shake We investigated the influence of sentence elaboration on self-regulated learning in order to examine age differences in resource allocation to the construction of textbase- and discourse-level representations. Older and younger adults learned about a topic by reading a series of sentences varying in elaboration (from simple factoids to highly elaborated text) and manner of presentation (progressive change in elaboration vs. random change in elaboration). Younger readers were more likely to recall information from factoids; older adults, from highly elaborated text. Relative to young, older readers showed an advantage in the progressive presentation condition, which minimised frequent changes between textbase- and discourse-level processing. Older adults showed poorer memory monitoring for factoids and less elaborated discourse relative to young, but when passages were highly elaborated or presented progressively, age differences were eliminated. Results support the idea that textbase- and discourse-level encoding arise from functionally distinct systems whose regulation depends on text properties and reader age. Copyright © 2008 John Wiley & Sons, Ltd. [source] Task-relevance and temporal synchrony between tactile and visual stimuli modulates cortical activity and motor performance during sensory-guided movementHUMAN BRAIN MAPPING, Issue 2 2009Sean K. Meehan Abstract Sensory-guided movements require the analysis and integration of task-relevant sensory inputs from multiple modalities. This article sought to: (1) assess effects of intermodal temporal synchrony upon modulation of primary somatosensory cortex (S1) during continuous sensorimotor transformations, (2) identify cortical areas sensitive to temporal synchrony, and (3) provide further insight into the reduction of S1 activity during continuous vibrotactile tracking previously observed by our group (Meehan and Staines 2007: Brain Res 1138:148,158). Functional MRI was acquired while participants received simultaneous bimodal (visuospatial/vibrotactile) stimulation and continuously tracked random changes in one modality, by applying graded force to a force-sensing resistor. Effects of intermodal synchrony were investigated, unbeknownst to the participants, by varying temporal synchrony so that sensorimotor transformations dictated by the distracter modality either conflicted (low synchrony) or supplemented (high synchrony) those of the target modality. Temporal synchrony differentially influenced tracking performance dependent upon tracking modality. Physiologically, synchrony did not influence S1 activation; however, the insula and superior temporal gyrus were influenced regardless of tracking modality. The left temporal-parietal junction demonstrated increased activation during high synchrony specific to vibrotactile tracking. The superior parietal lobe and superior temporal gyrus demonstrated increased activation during low synchrony specific to visuospatial tracking. As previously reported, vibrotactile tracking resulted in decreased S1 activation relative to when it was task-irrelevant. We conclude that while temporal synchrony is represented at higher levels than S1, interactions between inter- and intramodal mechanisms determines sensory processing at the level of S1. Hum Brain Mapp, 2009. © 2007 Wiley-Liss, Inc. [source] Effects of cooperative and competitive incentives on agility, quality, and speed in an experimental settingHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 4 2004Charlene A. Yauch Inter- and intraorganizational cooperation have been identified as essential characteristics of agile manufacturing. For this research, agility was compared using two experimental treatments: cooperative versus competitive. Student teams performed a task and were confronted with random changes to simulate a dynamic environment. Although differences were not statistically significant, the results show that cooperative incentives do not result in greater agility. Speed also decreased with cooperative incentives but quality improved. The experiment provides a preliminary understanding of how competition, cooperation, and agility interrelate and suggest that intra-organizational cooperation may not be the best means of achieving manufacturing agility. © 2004 Wiley Periodicals, Inc. Hum Factors Man 14: 403,413, 2004. [source] Southern hemisphere cyclones and anticyclones: recent trends and links with decadal variability in the Pacific OceanINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2007Dr Alexandre Bernardes Pezza Abstract The aim of this paper is to study the association between the extratropical Southern Hemisphere and the decadal variability in the Pacific Ocean (PO). We discuss a pattern of coherent large-scale anomalies and trends in cyclone and anticyclone behaviour in light of the climate variability in the PO over the ERA40 reanalysis period (1957,2002). The two representative PO indices are the Pacific Decadal and Interdecadal Oscillations (PDO and IPO), and here the PDO is chosen owing to it being less associated with the southern oscillation index (SOI). Composites of the indicators of the density and intensity of cyclones/anticyclones given by an automatic tracking scheme were calculated for the years when the PDOI was more than one standard deviation above or below its mean. Although the ERA40 is not free from noise and assimilation changes, the results show a large-scale feature, which seems to be robust and agrees with earlier studies using different data sets. The sea-level pressure shows a strong annular structure related to the PDO, which is not seen for the SOI, with lower pressure around Antarctica during the positive phase and vice versa. More intense (and fewer) cyclones and anticyclones were observed during the positive PDO. This is less consistent for the SOI, particularly during the summer when a different PDO/SOI pattern arises at high latitudes. The trends project a pattern coincident with the positive PDO phase and seem to be linked with the main climate shift in the late seventies. Trends observed over the Tasman Sea are consistent with declining winter rainfall over southeastern Australia. Most patterns are statistically significant and seem robust, but random changes in ENSO may play a part, to a certain degree, in modulating the results, and a physical mechanism of causality has not been demonstrated. Although global warming and related changes in the Southern Annular Mode (SAM) may also help explain the observed behaviour, the large-scale response presented here provides a new insight and would be of considerable interest for further modelling studies. Copyright © 2007 Royal Meteorological Society [source] Epigenetic gambling and epigenetic drift as an antagonistic pleiotropic mechanism of agingAGING CELL, Issue 6 2009George M. Martin Summary Generations of biogerontologists have been puzzled by the marked intraspecific variations in lifespan of their experimental model organisms despite all efforts to control both genotype and environment. The most cogent example comes from life table studies of wild-type Caenorhabditis elegans when grown in suspension cultures using axenic media. While nuclear and mitochondrial somatic mutations and ,thermodynamic noise' likely contribute to such lifespan variegations, I raise an additional hypothetical mechanism, one that may have evolved as a mechanism of phenotypic variation which could have preceded the evolution of meiotic recombination. I suggest that random changes in cellular gene expression (cellular epigenetic gambling or bet hedging) evolved as an adaptive mechanism to ensure survival of members of a group in the face of unpredictable environmental challenges. Once activated, it could lead to progressive epigenetic variegation (epigenetic drift) amongst all members of the group. Thus, while particular patterns of gene expression would be adaptive for a subset of reproductive individuals within a population early in life, once initiated, I predict that continued epigenetic drift will result in variable onsets and patterns of pathophysiology , perhaps yet another example of antagonistic pleiotropic gene action in the genesis of senescent phenotypes. The weakness of this hypothesis is that we do not currently have a plausible molecular mechanism for the putative genetic ,randomizer' of epigenetic expression, particularly one whose ,setting' may be responsive to the ecology in which a given species evolves. I offer experimental approaches, however, to search for the elusive epigenetic gambler(s). [source] | ||||||||||