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Unpredictable
Terms modified by Unpredictable Selected AbstractsAdventures in multivalency, the Harry S. Fischer memorial lecture CMR 2005; Evian, FranceCONTRAST MEDIA & MOLECULAR IMAGING, Issue 1 2006Michael F. Tweedle Abstract This review discusses multivalency in the context of drug discovery, specifically the discovery of new diagnostic imaging and related agents. The aim is to draw attention to the powerful role that multivalency plays throughout research involving molecular biology, in general, and much of biochemically targeted contrast agent research, in particular. Two examples from the author's laboratory are described. We created small (,5,kDa) peptide ,dimers' composed of two different, chemically linked peptides. The monomer peptides both bound to the same target protein with Kd,,,100,s,nM, while the heterodimers had sub-nM Kd values. Biological activity was evident in the heterodimers where none or very little existed in homodimers, monomers or monomer mixtures. Two different tyrosine kinases (KDR and C-Met) and four peptide families produced consistent results: multivalent heterodimers were uniquely different. The second example begins with making two micron ultrasound bubbles coated with the peptide, TKPPR (a Tuftsin antagonist) as a negative control for bubbles targeted with angiogenesis target-binding peptides. Unexpected binding of a ,negative' control, (TKPPR)-targeted bubble to endothelial cells expressing angiogenesis targets, led to the surprising result that TKPPR, only when multimerized, binds avidly, specifically and actively to neuropilin-1, a VEGF co-receptor. VEGF is the primary stimulator of angiogenesis. Tuftsin is a small peptide (TKPR) derived from IgG that binds to macrophages during inflammation, and has been studied for over 30 years. The receptor has never been cloned. The results led to new conclusions about Tuftsin, neuropilin-1 and the purpose, up to now unknown, of exon 8 in VEGF. Multivalency can be used rationally to solve practical problems in drug discovery. When targeting larger structures, multivalency is frequently unavoidable, and can lead to unpredictable and useful biochemical information, as well as to new drug candidates. Copyright © 2006 John Wiley & Sons, Ltd. [source] Pathological gambling: an increasing public health problemACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2001Article first published online: 7 JUL 200 Gambling has always existed, but only recently has it taken on the endlessly variable and accessible forms we know today. Gambling takes place when something valuable , usually money , is staked on the outcome of an event that is entirely unpredictable. It was only two decades ago that pathological gambling was formally recognized as a mental disorder, when it was included in the DSM-III in 1980. For most people, gambling is a relaxing activity with no negative consequences. For others, however, gambling becomes excessive. Pathological gambling is a disorder that manifests itself through the irrepressible urge to wager money. This disorder ultimately dominates the gambler's life, and has a multitude of negative consequences for both the gambler and the people they interact with, i.e. friends, family members, employers. In many ways, gambling might seem a harmless activity. In fact, it is not the act of gambling itself that is harmful, but the vicious cycle that can begin when a gambler wagers money they cannot afford to lose, and then continues to gamble in order to recuperate their losses. The gambler's ,tragic flaw' of logic lies in their failure to understand that gambling is governed solely by random, chance events. Gamblers fail to recognize this and continue to gamble, attempting to control outcomes by concocting strategies to ,beat the game'. Most, if not all, gamblers try in some way to predict the outcome of a game when they are gambling. A detailed analysis of gamblers' selfverbalizations reveals that most of them behave as though the outcome of the game relied on their personal ,skills'. From the gambler's perspective, skill can influence chance , but in reality, the random nature of chance events is the only determinant of the outcome of the game. The gambler, however, either ignores or simply denies this fundamental rule (1). Experts agree that the social costs of pathological gambling are enormous. Changes in gaming legislation have led to a substantial expansion of gambling opportunities in most industrialized countries around the world, mainly in Europe, America and Australia. Figures for the United States' leisure economy in 1996 show gross gambling revenues of $47.6 billion, which was greater than the combined revenue of $40.8 billion from film box offices, recorded music, cruise ships, spectator sports and live entertainment (2). Several factors appear to be motivating this growth: the desire of governments to identify new sources of revenue without invoking new or higher taxes; tourism entrepreneurs developing new destinations for entertainment and leisure; and the rise of new technologies and forms of gambling (3). As a consequence, prevalence studies have shown increased gambling rates among adults. It is currently estimated that 1,2% of the adult population gambles excessively (4, 5). Given that the prevalence of gambling is related to the accessibility of gambling activities, and that new forms of gambling are constantly being legalized throughout most western countries, this figure is expected to rise. Consequently, physicians and mental health professionals will need to know more about the diagnosis and treatment of pathological gamblers. This disorder may be under-diagnosed because, clinically, pathological gamblers usually seek help for the problems associated with gambling such as depression, anxiety or substance abuse, rather than for the excessive gambling itself. This issue of Acta Psychiatrica Scandinavica includes the first national survey of problem gambling completed in Sweden, conducted by Volberg et al. (6). This paper is based on a large sample (N=9917) with an impressively high response rate (89%). Two instruments were used to assess gambling activities: the South Oaks Gambling Screen-Revised (SOGS-R) and an instrument derived from the DSM-IV criteria for pathological gambling. Current (1 year) and lifetime prevalence rates were collected. Results show that 0.6% of the respondents were classified as probable pathological gamblers, and 1.4% as problem gamblers. These data reveal that the prevalence of pathological gamblers in Sweden is significantly less than what has been observed in many western countries. The authors have pooled the rates of problem (1.4%) and probable pathological gamblers (0.6%), to provide a total of 2.0% for the current prevalence. This 2% should be interpreted with caution, however, as we do not have information on the long-term evolution of these subgroups of gamblers; for example, we do not know how many of each subgroup will become pathological gamblers, and how many will decrease their gambling or stop gambling altogether. Until this information is known, it would be preferable to keep in mind that only 0.6% of the Swedish population has been identified as pathological gamblers. In addition, recent studies show that the SOGS-R may be producing inflated estimates of pathological gambling (7). Thus, future research in this area might benefit from the use of an instrument based on DSM criteria for pathological gambling, rather than the SOGS-R only. Finally, the authors suggest in their discussion that the lower rate of pathological gamblers obtained in Sweden compared to many other jurisdictions may be explained by the greater availability of games based on chance rather than games based on skill or a mix of skill and luck. Before accepting this interpretation, researchers will need to demonstrate that the outcomes of all games are determined by other factor than chance and randomness. Many studies have shown that the notion of randomness is the only determinant of gambling (1). Inferring that skill is an important issue in gambling may be misleading. While these are important issues to consider, the Volberg et al. survey nevertheless provides crucial information about gambling in a Scandinavian country. Gambling will be an important issue over the next few years in Sweden, and the publication of the Volberg et al. study is a landmark for the Swedish community (scientists, industry, policy makers, etc.). This paper should stimulate interesting discussions and inspire new, much-needed scientific investigations of pathological gambling. Acta Psychiatrica Scandinavica Guido Bondolfi and Robert Ladouceur Invited Guest Editors References 1.,LadouceurR & WalkerM. The cognitive approach to understanding and treating pathological gambling. In: BellackAS, HersenM, eds. Comprehensive clinical psychology. New York: Pergamon, 1998:588 , 601. 2.,ChristiansenEM. Gambling and the American economy. In: FreyJH, ed. Gambling: socioeconomic impacts and public policy. Thousand Oaks, CA: Sage, 1998:556:36 , 52. 3.,KornDA & ShafferHJ. Gambling and the health of the public: adopting a public health perspective. J Gambling Stud2000;15:289 , 365. 4.,VolbergRA. Problem gambling in the United States. J Gambling Stud1996;12:111 , 128. 5.,BondolfiG, OsiekC, FerreroF. Prevalence estimates of pathological gambling in Switzerland. Acta Psychiatr Scand2000;101:473 , 475. 6.,VolbergRA, AbbottMW, RönnbergS, MunckIM. Prev-alence and risks of pathological gambling in Sweden. Acta Psychiatr Scand2001;104:250 , 256. 7.,LadouceurR, BouchardC, RhéaumeNet al. Is the SOGS an accurate measure of pathological gambling among children, adolescents and adults?J Gambling Stud2000;16:1 , 24. [source] Verbatim and gist recall of sentences by dyslexic and non-dyslexic adultsDYSLEXIA, Issue 3 2006T. R. Miles Abstract Forty-eight college students, 24 of them dyslexic, were presented with four sentences of increasing complexity. Participants were asked to repeat each sentence and a record was kept of the number of repetitions required before 100% correct accuracy was achieved. None of the 24 control participants required a total of more than eight repetitions over the four sentences, whereas among the dyslexics the total number of repetitions needed ranged from one to 25. Dyslexic participants were unpredictable in their performance from one level of difficulty to the next and inter-individual variability was far greater in the dyslexic group than in the control group. Overall, despite their relatively poor performance in achieving verbatim accuracy relative to non-dyslexic participants, dyslexic individuals regularly managed to preserve the gist of the sentences. Some theoretical issues arising from these results are discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Elongation Index as a New Index Determining the Severity of Left Ventricular Systolic Dysfunction and Mitral Regurgitation in Patients with Congestive Heart FailureECHOCARDIOGRAPHY, Issue 7 2005Mehmet Yokusoglu M.D. The shape of the left ventricle is an important echocardiographic feature of left ventricular dysfunction. Progression of the mitral regurgitation and consequent left ventricular remodeling is unpredictable in heart failure. Elongation index is an index of left ventricular sphericity. The surface area of the elongated ventricle is larger than that of a spherical one. The objective of this study was to assess the relation between elongation index and the degree of mitral regurgitation along with noninvasive indices of left ventricular function. Thirty-two patients (21 male, 11 female, mean age: 57 ± 6 yrs) with congestive heart failure and mitral regurgitation were included. Patients were stratified into three groups according to vena contracta width as having mild (n = 11), moderate (n = 11) and severe mitral regurgitation (n = 10). The elongation index (EI) was considered as equal to {[(left ventricular internal area-measured) , (theoretical area of the sphere with measured left ventricular volume)]/(theoretical area of the sphere with measured left ventricular volume)}. Ejection fractions by the modified Simpson rule, dP/dt and sphericity index (SI) were also recorded. The relationship between (EI), ejection fraction, dP/dt and SI reached modest statistical significance (p < 0.05). When the EI and SI were compared, the correlation was also significant (p < 0.01). The areas under the receiver operator curve of EI and SI for discriminating dP/dt < 1000 mm Hg/s were 0.833 and 0.733, respectively. In conclusion, the elongation, which defines the shape of the left ventricle, might be related to the systolic function of the left ventricle and the degree of the mitral regurgitation. Further studies are needed to demonstrate its use in other clinical entities. [source] How do paedomorphic newts cope with lake drying?ECOGRAPHY, Issue 4 2003Mathieu Denoël Paedomorphosis, in which adult individuals retain larval traits, is widespread in newts and salamanders. Most evolutionary models predict the maintenance of this life-history trait in favourable aquatic habitats surrounded by hostile terrestrial environments. Nevertheless, numerous ponds inhabited by paedomorphic individuals are unpredictable and temporary. In an experimental framework, I showed that paedomorphic newts were able to metamorphose and thus survive in the absence of water. However, the mere decrease of water level or the life space do not seem to induce metamorphosis in paedomorphs. On the contrary, drying up induces almost all individuals to move on land and after that to colonize other aquatic sites located nearby. Such terrestrial migrations allow survival in drying conditions without metamorphosis as long as the distances of terrestrial migration are short. These results are consistent with the presence of paedomorphs in drying ponds and are in favor of classic optimality models predicting metamorphosis in unfavorable environments. [source] Food web complexity and chaotic population dynamicsECOLOGY LETTERS, Issue 3 2002Gregor F. Fussmann Abstract In mathematical models, very simple communities consisting of three or more species frequently display chaotic dynamics which implies that long-term predictions of the population trajectories in time are impossible. Communities in the wild tend to be more complex, but evidence for chaotic dynamics from such communities is scarce. We used supercomputing power to test the hypothesis that chaotic dynamics become less frequent in model ecosystems when their complexity increases. We determined the dynamical stability of a universe of mathematical, nonlinear food web models with varying degrees of organizational complexity. We found that the frequency of unpredictable, chaotic dynamics increases with the number of trophic levels in a food web but decreases with the degree of complexity. Our results suggest that natural food webs possess architectural properties that may intrinsically lower the likelihood of chaotic community dynamics. [source] Distribution, zoogeography and biology of the Murchison River hardyhead (Craterocephalus cuneiceps Whitley, 1944), an atherinid endemic to the Indian Ocean (Pilbara) Drainage Division of Western AustraliaECOLOGY OF FRESHWATER FISH, Issue 3 2005M. G. Allen Abstract , The Murchison River hardyhead (Craterocephalus cuneiceps) is endemic to the extremely arid Indian Ocean (Pilbara) Drainage Division of Western Australia, where it is found in the Greenough, Hutt, Murchison, Wooramel, Gascoyne and DeGrey rivers, but is absent from numerous rivers within its range. The most likely explanation for the disjunct contemporary distribution is that C. cuneiceps has simply never inhabited the rivers from which it is conspicuously absent (e.g. Ashburton and Fortescue). Biogeographical, geological and palaeoclimatic evidence is presented to support this hypothesis. In the Murchison River, breeding was extremely protracted with recruitment occurring throughout the year. The largest female and male specimens captured were 96 mm total length (TL; 7.73 g) and 86 mm TL (5.57 g), respectively. Sex ratio was 1.09 females:1 male. Batch fecundity ranged from 46 to 454 (mean 167.5 ± 25.7 SE). Estimates for the length at which 50 and 95% of females first spawned were 36.4 and 44.3 mm TL, respectively. Craterocephalus cuneiceps is essentially a detritivore, but also feeds on aquatic invertebrates. Rainfall in the Murchison River catchment is unpredictable and pH, salinity and temperature are variable. A specialised diet, small size and young age at maturity and protracted spawning period, coupled with serial spawning and high fecundity, allows the numerical dominance of this species in competitive, harsh, arid and unpredictable desert environments. Resumen 1. Craterocephalus cuneiceps es una especie endémica de las cuencas del Océano Indico (i.e., Pilbara) de Australia Occidental. Se encuentra en los ríos Greenough, Hutt, Murchison, Wooramel, Gascoyne y DeGrey pero está ausente en numerosos ríos dentro de su área de distribución. La explicación más probable para esta distribución separada en la actualidad es que C. cuneiceps no ha habitado nunca los ríos en los que está ausente tales como los ríos Ashburton y Fortescue. Presentamos evidencia bio-geográfica, geológica y paleo-climática para soportar esta hipótesis. 2. En el río Murchison, la reproducción es extremadamente prolongada con reclutamiento a lo largo de todo el año. Los mayores machos y hembras capturados alcanzaron 96 mm LT (7.73 g) y 86 mm LT (5.57 g), respectivamente. La proporción de sexos fue 1.09 hembras: 1 macho. La fecundidad varió entre 46 y 454 (media 167.5 ± 25.7 SE) y la longitudes a la que el 50 y el 95% de las hembras se reproducen por primera vez alcanzaron 36.4 y 44.3 mm LT, respectivamente. 3. C. cuneiceps es esencialmente detritívoro pero también se alimenta de invertebrados acuáticos. La lluvia sobre la cuenca del río Murchison es impredecible y el pH, la salinidad y la temperatura son variables. Una dieta especializada, pequeño tamaño, una edad joven en la madurez, y un período reproductivo prolongado, ademos de una freza seriada y alta fecundidad, permiten la dominancia numérica de la especie en ambientes competitivos, duros, áridos e impredecibles. [source] Predation risk allocation or direct vigilance response in the predator interaction between perch (Perca fluviatilis L.) and pike (Esox lucius L.)?ECOLOGY OF FRESHWATER FISH, Issue 3 2005A. Vainikka Abstract , Predation risk allocation hypothesis predicts that a prey's response to predator depends on prey's previous experience on predator. Here we tested whether the group of three perch respond differentially to pike, predator of perch, depending on the timing of high constant (HC) and high unpredictable (HU) risk periods within low constant risk periods in short-term (10 h) experiments, and whether the response is stronger during a HU risk period than during a HC risk period. Perch clearly erected the dorsal fin in response to predation risk treatments (pike odour only, odour and visible pike). Decrease in activity and increase in shoaling behaviour were observed mainly during high risk periods. However, the perch's responses to pike did not differ statistically between periods of various levels of predation risk or depending on the timing of high risk situations within constant low risk periods, and thus, suggesting that perch respond mainly to changes in the current predation risk. Resumen 1. La hipótesis de la asignación de riesgo a la predación predice que la respuesta a un predador depende de la experiencia previa de la presa al predador. En este trabajo analizamos si un grupo de tres individuos de Perca fluviatilis respondían de forma distinta a la presencia de Esox lucius, (un predador común de esta especie) y si éstas dependían del momento en el que se producen periodos de alto riesgo constante y de alto riesgo impredecible, en experimentos de corto plazo (10 horas) de riesgo bajo y constante y si la respuesta era mayor durante perí odos de riesgo impredecible y alto que durante períodos de riesgo constante alto. 2. Claramente P. fluviatilis respondió levantando la aleta dorsal en respuesta a los tratamientos de riesgo a la predación (solamente olor y olor + visibilidad de E. lucius). Una menor actividad y una mayor tendencia a la formación de bancos fueron observados durante períodos de alto riesgo. Sin embargo, las respuesta de P. fluviatilis a E. lucius no difirieron estadísticamente entre períodos de varios niveles de riesgo a la predación o entre aquellos que dependieron del momento en el que se produjeron situaciones de alto riesgo dentro de períodos de bajo riesgo constante. 3. Concluimos que P. fluviatilis puede utilizar señales olfatorias como determinantes de respuestas al riesgo a la predación y responder a aumentos de riesgo, sin excluir la posibilidad de que amenazas repetidas decrezcan la intensidad de la respuesta. Nuestros resultados, obtenidos en experimentos realizados a pequeña escala temporal, no niegan la posibilidad de la P. fluviatilis y otras especies puedan balancear la alimentación con actividades anti-predación, de acuerdo a cambios en el riesgo de predación a lo largo de escalas temporales de varios días. [source] Strategies of family farms to strengthen their resilienceENVIRONMENTAL POLICY AND GOVERNANCE, Issue 4 2010Ika Darnhofer Abstract Resilience thinking offers a framework to emphasize dynamics and interdependencies across time, space and domains. It is based on understanding social,ecological systems as complex, and future developments as unpredictable, thus emphasizing adaptive approaches to management. In this paper the four clusters of factors that have been identified as building resilience in large-scale social,ecological systems are applied at the farm level. Suggestions on how these factors could be operationalized at the farm level are derived from workshops held with family farmers in Austria. The results show that farmers understand change as unpredictable and unfolding, have a number of strategies to ensure the flexibility and adaptability of their farm and build extensive networks to diversify information and income sources. However, these strategies, while ensuring adaptability and transformability, compete for scarce resources. The farmers thus face trade-offs between strategies that ensure the adaptive capacity of their farm over the long term and those ensuring profitability over the short term. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment. [source] Examining the single and interactive effects of three insecticides on amphibian metamorphosis,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2008Michelle D. Boone Abstract Although aquatic communities frequently are exposed to a number of pesticides, the effects of chemical mixtures are not well understood. In two separate studies, I examined how insecticide mixtures influenced the likelihood of unpredictable, nonadditive effects on American toad (Bufo americanus) and green frog (Rana clamitans) tadpoles reared in outdoor aquatic communities. I exposed tadpoles to single or multiple insecticides at approximately half the reported median lethal concentrations using insecticides that were either acetylcholinesterase inhibitors (carbaryl or malathion) or a sodium-channel disruptor (permethrin). I found that combinations of insecticides with the same mode of action were more likely to have nonadditive effects on amphibian metamorphosis compared with those having different modes of action. Additionally, in one study, a commercial formulation of permethrin led to near-complete elimination of American toads, suggesting that this formulation could have adverse effects on aquatic communities. Many community studies exploring the ecological effects of expected environmental concentrations of pesticides have suggested that indirect effects in the food web, rather than direct effects on individual physiology, have the largest effect on amphibians. The present study indicates that direct effects of pesticides may become particularly important when insecticides with the same mode of action are present in the environment. [source] Cardiac sympathetic nerve activity during kainic acid,induced limbic cortical seizures in ratsEPILEPSIA, Issue 4 2009Harumi Hotta Summary We sought to define changes in cardiac sympathetic nerve activity that occur during seizures. We studied kainic acid,induced limbic cortical seizures in urethane-anesthetized rats using cardiac sympathetic nerve, blood pressure, and electrocardiography (ECG) recordings. We studied changes in ventilation rate before and during seizures. Cardiac sympathetic nerve activity was increased during limbic cortical seizures. The modest increases were similar to changes induced by nitroprusside infusion. The normal relation of cardiac sympathetic nerve activity to ventilation rate was lost during seizure activity. Changes in cardiac sympathetic nerve activity caused by changes in ventilation rate became unpredictable, and could be extreme. We conclude that the modest changes in cardiac sympathetic nerve activity contribute to the predominantly parasympathetic effects on the heart during limbic cortical seizures and periods of asphyxia. Further, ventilation rate changes might be associated with large sudden increases or decreases in cardiac sympathetic outflow during seizures. [source] Relation of apical dendritic spikes to output decision in CA1 pyramidal cells during synchronous activation: a computational studyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2006José M. Ibarz Abstract Recent studies on the initiation and propagation of dendritic spikes have modified the classical view of postsynaptic integration. Earlier we reported that subthreshold currents and spikes recruited by synaptic currents play a critical role in defining outputs following synchronous activation. Experimental factors strongly condition these currents due to their nonlinear behaviour. Hence, we have performed a detailed parametric study in a CA1 pyramidal cell model to explore how different variables interact and initiate dendritic spiking, and how they influence cell output. The input pattern, the relative excitability of axon and dendrites, the presence/modulation of voltage-dependent channels, and inhibition were cross analysed. Subthreshold currents and spikes on synaptically excited branches fired spikes in other branches to jointly produce different modalities of apical shaft spiking with a variable impact on cell output. Synchronous activation initiated a varying number and temporal scatter of firing branches that produced in the apical shaft-soma axis nonpropagating spikes, pseudosaltatory or continuous forward conduction, or backpropagation. As few as 6,10 local spikes within a time window of 2 ms ensure cell output. However, the activation mode varied extremely when two or more variables were cross-analysed, becoming rather unpredictable when all the variables were considered. Spatially clustered inputs and upper modulation of dendritic Na+ or Ca2+ electrogenesis favour apical decision. In contrast, inhibition biased the output decision toward the axon and switched between dendritic firing modes. We propose that dendrites can discriminate input patterns and decide immediate cell output depending on the particular state of a variety of endogenous parameters. [source] Predictive and reactive co-ordination of grip and load forces in bimanual lifting in manEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003R. Martyn Bracewell Abstract We investigated the intra- and inter-manual coordination of grip force (GF) and load force (LF) during bimanual lifting and holding of a single object. In a voluntary task involving lifting a predictable load (Experiment 1), we showed scaling of GF to LF generated by either hand, similar to effects seen in previous unimanual studies. Moreover, the GF rates generated by the two hands were correlated. In part this correlation was due to the correlation between the LF rates. However, the GF rates remained correlated when the effects of the correlation in LF rates were partialled out. This novel finding suggests an additional co-ordinative constraint at the level of specification of GFs. As a contrast to the predictable loading in the first experiment, in the second experiment loading was temporally unpredictable and elicited reactive increases in GF. In Experiment 2, the intermanual correlation of GF rates was stronger than in Experiment 1. We speculate that this result reflects greater degrees of co-ordinative constraint at lower levels in the motor control hierarchy. [source] The roles of the cerebellum and basal ganglia in timing and error predictionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2002Jean-Claude Dreher Abstract Recent evidence that the cerebellum and the basal ganglia are activated during the performance of cognitive and attention tasks challenges the prevailing view of their primary function in motor control. The specific roles of the basal ganglia and the cerebellum in cognition, however, have been difficult to identify. At least three functional hypotheses regarding their roles have been proposed. The first hypothesis suggests that their main function is to switch attentional set. The second hypothesis states that they provide error signals regarding stimuli or rewards. The third hypothesis is that they operate as an internal timing system, providing a precise representation of temporal information. Using functional magnetic resonance imaging, we tested these three hypotheses using a task-switching experiment with a 2 × 2 factorial design varying timing (random relative to fixed) and task order (unpredictable relative to predictable). This design allowed us to test whether switching between tasks, timing irregularity and/or task order unpredictability activate the basal ganglia and/or the cerebellum. We show that the cerebellum is primarily activated with timing irregularity while the anterior striatum is activated with task order unpredictability, supporting their distinctive roles in two forms of readjustment. Task order unpredictability alone, independent of reward delivery, is sufficient to induce striatal activation. In addition, activation of the cerebellum and basal ganglia were not specific to switching attention because these regions were both activated during switching between tasks and during the simultaneous maintenance of two tasks without switching between them. [source] Detection of animals in natural images using far peripheral visionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2001Simon J. Thorpe Abstract It is generally believed that the acuity of the peripheral visual field is too poor to allow accurate object recognition and, that to be identified, most objects need to be brought into foveal vision by using saccadic eye movements. However, most measures of form vision in the periphery have been done at eccentricities below 10° and have used relatively artificial stimuli such as letters, digits and compound Gabor patterns. Little is known about how such data would apply in the case of more naturalistic stimuli. Here humans were required to categorize briefly flashed (28 ms) unmasked photographs of natural scenes (39° high, and 26° across) on the basis of whether or not they contained an animal. The photographs appeared randomly in nine locations across virtually the entire extent of the horizontal visual field. Accuracy was 93.3% for central vision and decreased almost linearly with increasing eccentricity (89.8% at 13°, 76.1% at 44.5° and 71.2% at 57.5°). Even at the most extreme eccentricity, where the images were centred at 70.5°, subjects scored 60.5% correct. No evidence was found for hemispheric specialization. This level of performance was achieved despite the fact that the position of the image was unpredictable, ruling out the use of precued attention to target locations. The results demonstrate that even high-level visual tasks involving object vision can be performed using the relatively coarse information provided by the peripheral retina. [source] HOW REPEATABLE IS ADAPTIVE EVOLUTION?EVOLUTION, Issue 8 2008THE ROLE OF GEOGRAPHICAL ORIGIN AND FOUNDER EFFECTS IN LABORATORY ADAPTATION The importance of contingency versus predictability in evolution has been a long-standing issue, particularly the interaction between genetic background, founder effects, and selection. Here we address experimentally the effects of genetic background and founder events on the repeatability of laboratory adaptation in Drosophila subobscura populations for several functional traits. We found disparate starting points for adaptation among laboratory populations derived from independently sampled wild populations for all traits. With respect to the subsequent evolutionary rate during laboratory adaptation, starvation resistance varied considerably among foundations such that the outcome of laboratory evolution is rather unpredictable for this particular trait, even in direction. In contrast, the laboratory evolution of traits closely related to fitness was less contingent on the circumstances of foundation. These findings suggest that the initial laboratory evolution of weakly selected characters may be unpredictable, even when the key adaptations under evolutionary domestication are predictable with respect to their trajectories. [source] Climate change and the future for coral reef fishesFISH AND FISHERIES, Issue 3 2008Philip L Munday Abstract Climate change will impact coral-reef fishes through effects on individual performance, trophic linkages, recruitment dynamics, population connectivity and other ecosystem processes. The most immediate impacts will be a loss of diversity and changes to fish community composition as a result of coral bleaching. Coral-dependent fishes suffer the most rapid population declines as coral is lost; however, many other species will exhibit long-term declines due to loss of settlement habitat and erosion of habitat structural complexity. Increased ocean temperature will affect the physiological performance and behaviour of coral reef fishes, especially during their early life history. Small temperature increases might favour larval development, but this could be counteracted by negative effects on adult reproduction. Already variable recruitment will become even more unpredictable. This will make optimal harvest strategies for coral reef fisheries more difficult to determine and populations more susceptible to overfishing. A substantial number of species could exhibit range shifts, with implications for extinction risk of small-range species near the margins of reef development. There are critical gaps in our knowledge of how climate change will affect tropical marine fishes. Predictions are often based on temperate examples, which may be inappropriate for tropical species. Improved projections of how ocean currents and primary productivity will change are needed to better predict how reef fish population dynamics and connectivity patterns will change. Finally, the potential for adaptation to climate change needs more attention. Many coral reef fishes have geographical ranges spanning a wide temperature gradient and some have short generation times. These characteristics are conducive to acclimation or local adaptation to climate change and provide hope that the more resilient species will persist if immediate action is taken to stabilize Earth's climate. [source] Rainfall in arid zones: possible effects of climate change on the population ecology of blue cranesFUNCTIONAL ECOLOGY, Issue 5 2009Res Altwegg Summary 1.,Understanding the demographic mechanisms through which climate affects population dynamics is critical for predicting climate change impacts on biodiversity. In arid habitats, rainfall is the most important forcing climatic factor. Rainfall in arid zones is typically variable and unpredictable, and we therefore hypothesise that its seasonality and variability may be as important for the population ecology of arid zone animals as its total amount. 2.,Here we examine the effect of these aspects of rainfall on reproduction and age specific survival of blue cranes (Anthropoides paradiseus Lichtenstein) in the semi-arid eastern Nama Karoo, South Africa. We then use our results to predict the effect of changes in rainfall at the population level. 3.,Using combined capture-mark-resighting and dead-recovery models, we estimated average survival of cranes to be 0·53 in their first year, 0·73 in their second and third year, and 0·96 for older birds. 4.,We distinguished between three seasons, based on the blue cranes' breeding phenology: early breeding season, late breeding season and nonbreeding season. Cranes survived better with increasing rainfall during the late but not early breeding season. Based on road counts and success of monitored nests, reproduction was positively associated with rainfall during the early but not late breeding season. 5.,A matrix population model predicted that population growth rate would increase with increasing rainfall. A stochastic analysis showed that variation in early breeding season rainfall increased population growth slightly due to the nonlinear relationship between rainfall and reproduction. This effect was opposed by the effect of variation in late breeding season rainfall on survival and overall, variation in rainfall had a negligible effect on population growth. 6.,Our results allow predictions to be made for a range of climate-change scenarios. For example, a shift in seasonality with drier springs but wetter summers would likely decrease reproduction but increase survival, with little overall effect on population growth. [source] Environmentally induced variation in floral traits affects the mating system in Datura wrightiiFUNCTIONAL ECOLOGY, Issue 1 2002E. Elle Summary 1If pollination is unpredictable, selection may favour the production of selfed seeds in the absence of pollen vectors, even in plant species with obvious adaptations for outcrossing. Pollination may be less predictable for plants growing in certain environments if environmental factors affect the floral phenotype. Through effects on flower morphology and the floral display, the environment may affect the outcrossing rate. 2We manipulated two environmental factors, water availability and exposure to insect herbivores, in a common-garden experiment using a perennial herb, Datura wrightii. We measured herkogamy (the separation of anthers and stigmas within flowers), total flower length, and flower number, and used a single-gene trichome dimorphism as a marker to determine per-plant outcrossing rates. 3The large amount of variation in herkogamy was affected by trichome type, irrigation and herbivory. In addition, watered plants had longer corollas, and plants attacked by herbivores had fewer open flowers. Thus environmental factors affect floral phenotype. 4However, irrigation and herbivory did not directly affect outcrossing rate. There were indirect effects of these treatments on outcrossing because plants with increased herkogamy and fewer open flowers had higher outcrossing rates. 5, A greenhouse experiment showed that autonomous selfing is more likely when herkogamy is reduced, and can occur both as the flower opens and when the corolla is shed. 6, These experiments are among the first to show that within-population variation in the mating system can be due to environmentally induced variation in floral traits. [source] Allergy-like reactions to iodinated contrast agents.FUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2005A critical analysis Abstract Allergy-like reactions may occur following administration of iodinated contrast media (CM), mostly in at-risk patients (patients with history of previous reaction, history of allergy, co-treated with interleukin-2 or beta-blockers, etc.) but remain generally unpredictable. Severe and fatal reactions are very rare events. All categories of CM may induce such reactions, although first generation (high osmolar CM) have been found to induce a higher rate of adverse events than low osmolar CM. However, no differences were found between the two categories of CM with respect to mortality. Delayed reactions can also occur. There are no differences between the various categories of CM except for non-ionic dimers, which are more likely to induce such effect. Numerous clinical studies have evaluated the prophylactic value of drugs (mostly antihistamines and corticosteroids). Results are unclear and highly variable. Any prevention depends upon the mechanism involved. However, the mechanism of CM-induced allergy-like reaction remains disputed. Relatively recent data revived the hypothesis of a type-I hypersensitivity mechanism. Positive skin tests to CM have been reported. However, the affinity of IgE towards CM has been found to be very low in the only study which actually evaluated it. Other pathophysiological mechanisms (involving direct secretory effects on mast cells or basophils, or activation of the complement system associated or not with the plasma contact system) are also much debated. Anaphylaxis and anaphylactoid reactions are, in the end, clinically undistinguishable. [source] Machine Politics and Democracy: The Deinstitutionalization of the Argentine Party System1GOVERNMENT AND OPPOSITION, Issue 4 2008Gerardo Scherlis This article contends that intra-party dynamics based on particularistic exchanges constitute a double-edged sword for a political system. On the one hand, they provide party leaders with strategic flexibility, which can be essential for their party stability and for the governability of the political system. On the other hand, in permitting office holders to switch policies whenever they consider fit, these dynamics render governments unpredictable and unaccountable in partisan terms, thus debasing the quality of democratic representation. The hypothesis is illustrated by recent Argentine political development. [source] Prenatal stress modifies hippocampal synaptic plasticity and spatial learning in young rat offspringHIPPOCAMPUS, Issue 5 2006Jianli Yang Abstract Clinical studies demonstrate that prenatal stress causes cognitive deficits and increases vulnerability to affective disorders in children and adolescents. The underlying mechanisms are not yet fully understood. Here, we reported that prenatal stress (10 unpredictable, 1 s, 0.8 mA foot shocks per day during gestational days 13,19) impaired long-term potentiation (LTP) but facilitated long-term depression (LTD) in hippocampal CA1 region in slices of the prenatal stressed offspring (5 weeks old). Cross-fostering neonate offspring by the prenatal stressed or control mothers did not change the effects of prenatal stress on the hippocampal LTP and LTD. Furthermore, prenatal stress enhanced the effects of acute stress on the hippocampal LTP and LTD and impaired spatial learning and memory in the Morris water maze in the young rat offspring. Therefore, prenatal stress alters synaptic plasticity and enhances the effects of acute stress on synaptic plasticity in the hippocampus, which may be the mechanism for the impaired spatial learning and memory in young rat offspring. © 2006 Wiley-Liss, Inc. [source] Quantitative evaluation of strategies for erosion control on a railway embankment batterHYDROLOGICAL PROCESSES, Issue 17 2001Y. Gyasi-Agyei Abstract Strategies for erosion control on a railway embankment batter (side slope) are quantitatively evaluated in this paper. The strategies were centred on control (,do nothing' treatment), grass seeding, gypsum application, jute mat (an erosion control blanket) placement and planting hedgerows of Monto vetiver grass. Rainfall and runoff were monitored at 1 min intervals on 10 m wide embankment batter plots during 1998 and 1999. Total bedload and suspended sediment eroded from the plots were also measured but only for a group of storm events within sampling intervals. It has been demonstrated that vetiver grass is not cost-effective in controlling erosion on railway batters within Central Queensland region. Seeding alone could cause 60% reduction in the erosion rate compared with the control treatment. Applying gypsum to the calcium-deficient soil before seeding yielded an additional 25% reduction in the erosion rate. This is the result, primarily, of 100% grass cover establishment within seven months of sowing. Therefore, for railway embankment batter erosion control, the emphasis needs to be on rapid establishment of 100% grass cover. For rapid establishment of grass cover, irrigation is necessary during the initial stages of growth as the rainfall is unpredictable and the potential evaporation exceeds rainfall in the study region. The risk of seeds and fertilizers being washed out by short-duration and high-intensity rainfall events during the establishment phase may be reduced by the use of erosion control blankets on sections of the batters. Accidental burning of grasses on some plots caused serious erosion problems, resulting in very slow recovery of grass growth. It is therefore recommended that controlled burning of grasses on railway batters should be avoided to protect batters from being exposed to severe erosion. Copyright © 2001 John Wiley & Sons, Ltd. [source] Effects of food abundance and predictability on body condition and health parameters: experimental tests with the Hooded CrowIBIS, Issue 4 2002Camilla Acquarone It has been shown that small passerines can counteract variability of food resources by actively regulating their body reserves through an increase of mass. However, the effects of food predictability on body mass regulation and other body parameters, such as immune functions, in larger species have been little studied. To analyse the response of the Hooded Crow Corvus corone to food abundance and predictability, we performed three experiments with controlled food provisioning under laboratory conditions. Body mass, TOBEC (total body electrical conductivity) lean mass index, blood parameters and immune organ masses were measured at the beginning and end of a 15-day period. In the first experiment, the food release was predictable (same amount each day) but the quantity of food delivered to five groups of birds varied (37, 75, 100, 150 or 300 g/day). Low food levels induced a greater decrease in mass accompanied by an increase in erythrocyte sedimentation rate. In the second experiment, the same average quantity of food (100 g) was supplied according to either predictable or unpredictable (random) schedules. In this case, the crows lost more mass, and their erythrocyte sedimentation rate increased when food was unpredictable. In the third experiment, the same average quantity of food (150 g) was supplied according to either a predictable schedule or two schedules with different levels of variability. The group with a low level of variability did not differ from the control, while the group with a highly variable feeding schedule lost more mass. In this group, the higher mass loss was associated with greater variation of the erythrocyte sedimentation rate and a reduced Phytohaemagglutinin index of immunocompetence and haematocrit value. The results of experiments 2 and 3 contrast with findings in other passerines, which increase their mass when food availability is unpredictable. It appears that a body mass decrease in the Hooded Crow can be induced by a reduction of either food abundance (exp. 1) or food predictability (exp. 2, 3), and it is accompanied by a worsening of health state. [source] Preliminary evidence supporting a framework of psychological adjustment to inflammatory bowel disease,INFLAMMATORY BOWEL DISEASES, Issue 10 2010Jennifer L. Kiebles PhD Abstract Background: Adjustment to chronic disease is a multidimensional construct described as successful adaptation to disease-specific demands, preservation of psychological well-being, functional status, and quality of life. Inflammatory bowel disease (IBD) can be particularly challenging due to the unpredictable, relapsing and remitting course of the disease. Methods: All participants were patients being treated in an outpatient gastroenterology clinic at a university medical center. Participants completed a survey of questionnaires assessing illness perceptions, stress, emotional functioning, disease acceptance, coping, disease impact, and disease-specific and health-related quality of life. Adjustment was measured as a composite of perceived disability, psychological functioning, and disease-specific and health-related quality of life. Results: Participants were 38 adults with a diagnosis of either Crohn's disease (45%) or ulcerative colitis (55%). We observed that our defined adjustment variables were strongly correlated with disease characteristics (r = 0.33,0.80, all P < 0.05), an emotional representation of illness (r = 0.44,0.58, P < 0.01), disease acceptance (r = 0.34,0.74, P < 0.05), coping (r = 0.33,0.60, P < 0.05), and frequency of gastroenterologist visits (r = 0.39,0.70, P < 0.05). Better adjustment was associated with greater bowel and systemic health, increased activities engagement and symptom tolerance, less pain, less perceived stress, and fewer gastroenterologist visits. All adjustment variables were highly correlated (r = 0.40,0.84, P < 0.05) and demonstrated a cohesive composite. Conclusions: The framework presented and results of this study underscore the importance of considering complementary pathways of disease management including cognitive, emotional, and behavioral factors beyond the traditional medical and psychological (depression and anxiety) components. (Inflamm Bowel Dis 2010) [source] Mediating between predetermined order and chaos: the role of the teacher in task-based language educationINTERNATIONAL JOURNAL OF APPLIED LINGUISTICS, Issue 3 2009Kris Van den Branden interactie; taakgericht onderwijs; leerkracht; taalleren Tasks are not blueprints for action. A number of empirical studies carried out in authentic classrooms have shown that teachers and students reinterpret the tasks they are offered by syllabus developers in ways that suit their own purposes, learning needs, and interaction styles. This observation has raised fundamental questions about the degree to which teachers who are working with tasks can make any prediction concerning the learning that will come of out of task-based interactional work. In addition, if learners' reactions to tasks are fairly unpredictable, teachers may be inclined to associate task-based work with organisational chaos and with the seemingly unattainable challenge of having to cater to every individual learner's personal whims. Drawing on classroom-based research carried out in Flanders, and describing two task-based lessons that were observed in authentic Dutch as a second language (DSL) classrooms, this paper shows that between the extremes of deterministic predictability on the one hand and complete chaos on the other lies a rich pedagogical space that teachers and learners who work with tasks can exploit to construct shared projects with clearly determined goals. Taaltaken zijn geen blauwdruk voor activiteit in de klas. Uit heel wat onderzoek naar klasinteractie blijkt dat leerkrachten en leerlingen de taken die ze krijgen voorgeschoteld, herinterpreteren, zodat ze beter aansluiten bij hun leerstijlen, interesses en interactiestijl. Dit roept de vraag op of leerkrachten die met taken werken nog wel enige voorspelling kunnen doen over wat hun leerlingen uit de taakuitvoering zullen leren. Bovendien dreigen heel wat leerkrachten taakgericht onderwijs te associëren met chaos in de klas, en met de schier onhaalbare uitdaging om op alle behoeften en reacties van alle individuele leerlingen te moeten inspelen. Op basis van onderzoek in Vlaamse klassen, en voortbouwend op 2 taakgerichte lessen die werden geobserveerd in Vlaamse NT2-klassen, illustreert dit artikel dat er tussen chaos en complete voorspelbaarheid een rijke pedagogische ruimte ligt. Binnen die pedagogische ruimte gaan leerkrachten en leerlingen samen aan de slag rond een gezamenlijk taakgericht project met duidelijke doeleinden. [source] Characterization of the electrical energy consumption of a building for the dimensioning of a solar-hydrogen energy systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2010S. Véjar Abstract The photovoltaic (PV) applications where the dimensioning is effected through the daily energy balance criteria obtained by the estimation of the energy consumption depending on the power and time of use of the electrical apparatus are limited to autonomous PV systems with well-defined end use. Applications where one would like to electrify complex end use, such as office buildings, schools, hospitals, laboratories, residential units, etc., quantifying the daily energy consumption is difficult mainly due to two aspects. First, there will be great number of a variety of electrical appliances and second the proportionate electrical consumption of each one of them is unpredictable. For this reason it is necessary to establish a methodology that permits one to quantify precisely the daily energy consumption pattern to predict the energetic functioning of the PV system whose size may be determined by this procedure. In this work we describe a methodology for the energetic quantification of the installed equipments by using a Power Quality Analyzer to obtain the historical global energy consumption, daily energy consumption (kWh,day,1, kVAh,day,1) and the energy quality for the dimensioning of the PV system. Copyright © 2009 John Wiley & Sons, Ltd. [source] Sampling and design challenges in studying the mental health consequences of disastersINTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue S2 2008Sandro Galea Abstract Disasters are unpredictable and frequently lead to chaotic post-disaster situations, creating numerous methodologic challenges for the study of the mental health consequences of disasters. In this commentary, we expand on some of the issues addressed by Kessler and colleagues, largely focusing on the particular challenges of (a) defining, finding, and sampling populations of interest after disasters and (b) designing studies in ways that maximize the potential for valid inference. We discuss these challenges , drawing on specific examples , and suggest potential approaches to each that may be helpful as a guide for future work. We further suggest research directions that may be most helpful in moving the field forward. Copyright © 2008 John Wiley & Sons, Ltd. [source] From preparedness to partnerships: case study research on humanitarian logisticsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 5 2009Rolando M. Tomasini Abstract Disasters are on the rise, more complex, and donor support is increasingly unpredictable. In response to this trend humanitarian agencies are looking for more efficient and effective solutions. This paper discusses the evolution of supply chain management in disaster relief and the role of new players like the private sector. It is based on research conducted by the Humanitarian Research Group at INSEAD. [source] Primary mucinous eccrine carcinoma of the skin , a rare clinical tumor with many differential diagnosesJOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 6 2010Ina M. Scholz Summary Primary mucinous eccrine carcinoma of the skin is an extremely rare tumor most frequently occurring in the face or capillitium. It is felt to be an eccrine carcinoma, characterized by slow progress and unpredictable locally infiltrative growth. Therefore micrographic surgery is important to avoid local recurrence. It can be difficult to differentiate this carcinoma histologically from cutaneous metastases of breast or gastrointestinal tumors. Because of this, a primary staging in affected patients is essential. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||