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Search Results: 1 - 10 of 146664 matches for " Ethan K Scott "
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Fin-Tail Coordination during Escape and Predatory Behavior in Larval Zebrafish
Phil McClenahan, Michael Troup, Ethan K. Scott
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032295
Abstract: Larval zebrafish innately perform a suite of behaviors that are tightly linked to their evolutionary past, notably escape from threatening stimuli and pursuit and capture of prey. These behaviors have been carefully examined in the past, but mostly with regard to the movements of the trunk and tail of the larvae. Here, we employ kinematics analyses to describe the movements of the pectoral fins during escape and predatory behavior. In accord with previous studies, we find roles for the pectoral fins in slow swimming and immediately after striking prey. We find novel roles for the pectoral fins in long-latency, but not in short-latency C-bends. We also observe fin movements that occur during orienting J-turns and S-starts that drive high-velocity predatory strikes. Finally, we find that the use of pectoral fins following a predatory strike is scaled to the velocity of the strike, supporting a role for the fins in braking. The implications of these results for central control of coordinated movements are discussed, and we hope that these results will provide baselines for future analyses of cross-body coordination using mutants, morphants, and transgenic approaches.
Focusing on optic tectum circuitry through the lens of genetics
Linda M Nevin, Estuardo Robles, Herwig Baier, Ethan K Scott
BMC Biology , 2010, DOI: 10.1186/1741-7007-8-126
Abstract: The transformation of visual sensory inputs into motor and endocrine responses requires specialized neural processing, often distributed across multiple structures or pathways in the brain. A classical and still vigorous branch of neuroscience, best referred to as 'functional neuroanatomy', assigns functions to specific areas in the brain. The interconnectivity of multiple areas involved in a particular sensory or behavioral task are often represented using a set of boxes, connected by arrows. The most famous such wiring diagram identified roughly 40 visual processing areas in primates [1]. Similar 'macro-circuits' have been drawn up for the visual pathway of 'lower' vertebrates [2]. In toads, a detailed circuit underlying prey capture behavior has been derived from heroic work over three decades involving tract tracing and electrophysiological mapping [3] (Figure 1a). However, none of these studies has generated a comprehensive list of essential circuit components (cell types and their connections) for a specific behavior or the processing of a specific visual stimulus. This gap in our knowledge of 'micro-circuitry' is a major obstacle to understanding the mechanisms of perception and behavior.The zebrafish has emerged as a valuable model system with which we can hope to close this gap [4-7]. Ten different anatomical areas have been identified that serve as targets for the retinal ganglion cell (RGC) axons that connect the eye to the brain [8] (Figure 1b). These ten arborization fields, referred to as AF1 to AF10, probably correspond to the primary visual nuclei identified in adult teleost fish and are homologous to areas in mammals, such as the suprachiasmatic nuclei (AF1), the pretectal nucleus of the optic tract (AF9) and the superior colliculus/optic tectum (AF10). Not very much is known about the behavioral functions of these arborization fields in zebrafish or other fish species (with the exception of the optic tectum - see below), but it is clear that specif
Dendritic development of Drosophila high order visual system neurons is independent of sensory experience
Ethan K Scott, John E Reuter, Liqun Luo
BMC Neuroscience , 2003, DOI: 10.1186/1471-2202-4-14
Abstract: We find that the dendrites of VS1 neurons are unchanged in dark-reared flies as compared to control flies raised on a 12 hour light, 12 hour dark cycle. The dendrites of these flies show no differences from control in dendrite complexity, spine number, spine density, or axon complexity. Flies with genetically ablated eyes show a slight but significant reduction in the complexity and overall length of VS1 dendrites, although this effect may be due to a reduction in the overall size of the dendritic field in these flies.Overall, our results indicate no role for visual experience in the development of VS dendrites, while spontaneous activity from photoreceptors may play at most a subtle role in the formation of fully complex dendrites in these high-order visual processing neurons.The mechanisms that underlie the development of the nervous system are numerous and diverse. Over the past several decades, research has begun to give us a sense of the importance of both preprogrammed, invariant mechanisms for neural development, and also programs for development that depend on experience and the electrical activity of the developing neurons themselves. The fact that certain types of neurons develop their basic morphologies even when isolated in culture from other cells provides a simple but powerful argument for the importance of cell autonomous mechanisms in the establishment of neuronal structure [1,2]. These and numerous other experiments have provided overwhelming evidence that neurons possess endogenous, activity independent programs that account for important aspects of their development.On the other hand, neurons deprived of contact with or activity from their normal synaptic partners seldom attain a fully mature structure. For example, Purkinje cells deprived of their efferent projections in Weaver mice have dendritic arborizations that do not extend normally [3]. Additionally, the structures of neurons can be affected by an absence of activity from their efferent pa
Evaluation of a Wet Chemistry Method for Isolation of Cyclotron Produced [211At]Astatine
Ethan R. Balkin,Donald K. Hamlin,Katherine Gagnon,Ming-Kuan Chyan,Sujit Pal,Shigeki Watanabe,D. Scott Wilbur
Applied Sciences , 2013, DOI: 10.3390/app3030636
Abstract: A “wet chemistry” approach for isolation of 211At from an irradiated bismuth target is described. The approach involves five steps: (1) dissolution of bismuth target in conc. HNO 3; (2) removal of the HNO 3 by distillation; (3) dissolution of residue in 8 M HCl; (4) extraction of 211At from 8 M HCl into DIPE; and (5) extraction of 211At from DIPE into NaOH. Results from 55 “optimized” 211At isolation runs gave recovery yields of approximately 78% after decay and attenuation corrections. An attenuation-corrected average of 26 ± 3 mCi in the target provided isolated (actual) yields of 16 ± 3 mCi of 211At. A sixth step, used for purification of 211At from trace metals, was evaluated in seven runs. In those runs, isolated 211At was distilled under reductive conditions to provide an average 71 ± 8% recovery. RadioHPLC analyses of the isolated 211At solutions, both initial and after distillation, were obtained to examine the 211At species present. The primary species of 211At present was astatide, but astatate and unidentified species were also observed. Studies to determine the effect of bismuth attenuation on 211At were conducted to estimate an attenuation factor (~1.33) for adjustment of 211At readings in the bismuth target.
Transient Knockdown of Tyrosine Hydroxylase during Development Has Persistent Effects on Behaviour in Adult Zebrafish (Danio rerio)
Isabel Formella, Ethan K. Scott, Tom H. J. Burne, Lauren R. Harms, Pei-Yun Liu, Karly M. Turner, Xiaoying Cui, Darryl W. Eyles
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042482
Abstract: Abnormal dopamine (DA) signaling is often suggested as causative in schizophrenia. The other prominent hypothesis for this disorder, largely driven by epidemiological data, is that certain adverse events during the early stages of brain development increase an individual's risk of developing schizophrenia later in life. However, the clinical and preclinical literature consistently implicates behavioural, cognitive, and pharmacological abnormalities, implying that DA signaling is abnormal in the adult brain. How can we reconcile these two major hypotheses underlying much of the clinical and basic research into schizophrenia? In this study we have transiently knocked down tyrosine hydroxylase (TH, the rate limiting enzyme in DA synthesis) gene expression in the early stages of brain development in zebrafish using morpholinos. We show that by adulthood, TH and DA levels have returned to normal and basic DA-mediated behaviours, such as locomotion, are also normal. However, when they were exposed to a novel environment the levels of freezing and immediate positioning in deeper zones were significantly reduced in these adult fish. The neurochemistry underlying these behaviours is complex, and the exact mechanisms for these abnormal behaviours remains unknown. This study demonstrates that early transient alterations in DA ontogeny can produce persistent alterations in adult brain function and suggests that the zebrafish may be a promising model animal for future studies directed at clarifying the basic neurodevelopmental mechanisms behind complex psychiatric disease.
A Module System for Domain-Specific Languages
Ethan K. Jackson
Computer Science , 2014, DOI: 10.1017/S1471068414000337
Abstract: Domain-specific languages (DSLs) are routinely created to simplify difficult or specialized programming tasks. They expose useful abstractions and design patterns in the form of language constructs, provide static semantics to eagerly detect misuse of these constructs, and dynamic semantics to completely define how language constructs interact. However, implementing and composing DSLs is a non-trivial task, and there is a lack of tools and techniques. We address this problem by presenting a complete module system over LP for DSL construction, reuse, and composition. LP is already useful for DSL design, because it supports executable language specifications using notations familiar to language designers. We extend LP with a module system that is simple (with a few concepts), succinct (for key DSL specification scenarios), and composable (on the level of languages, compilers, and programs). These design choices reflect our use of LP for industrial DSL design. Our module system has been implemented in the FORMULA language, and was used to build key Windows 8 device drivers via DSLs. Though we present our module system as it actually appears in our FORMULA language, our emphasis is on concepts adaptable to other LP languages.
Megacities and the Environment
Ethan H. Decker,Scott Elliott,Felisa A. Smith
The Scientific World Journal , 2002, DOI: 10.1100/tsw.2002.103
XForms for Libraries, An Introduction
Ethan Gruber,Chris Fitzpatrick,Bill Parod,Scott Prater
Code4Lib Journal , 2010,
Abstract: XForms applications can be used to create XML metadata that is well-formed and valid according to the schema, and then saved to (or loaded from) a datastore that communicates via REST or SOAP. XForms applications provide a powerful set of tools for data creation and manipulation, as demonstrated by some projects related to library workflows that are described in this paper.
An Isothermal Study of the Electrochemical Performance of Intermediate Temperature Solid Oxide Fuel Cells  [PDF]
O. O. Ighodaro, K. Scott, L. Xing
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.52006
Abstract: A two-dimensional along the channel micro-scale isothermal model of a SOFC is developed and validated against experimental data and other simulated results from literature. The steady state behaviour of the cell was determined by numerical solution of the combined transport, continuity and kinetic equations. An important characteristic of the model is the consideration of the triple phase boundary as a distinct layer. The model is capable of predicting the cell performance including polarisation behaviour and power output. The model is used to study the effect of the support structure, geometric parameters and the effect of operating conditions on cell performance. Several parametric studies include the effect of operating conditions and geometric parameters on cell performance with a view to optimising the cell. The simulation results showed that the anode supported SOFC displayed the best performance with the activation and ohmic overpotentials being responsible for most of the voltage losses in the cell.
Economics of Pooling Small Local Electricity Prosumers—Prosumer vs Business as Usual Approach  [PDF]
Peter K?stel, Bryce Gilroy-Scott
Energy and Power Engineering (EPE) , 2018, DOI: 10.4236/epe.2018.105016
Abstract: This paper analyses the economics of pooling small UK based local electricity prosumers with back-up access to the National Grid and compares it to the current conventional UK electricity supply model—business as usual (BAU) approach. This is contextualized against the UK energy market framework, prosumer research and changing energy market dynamics. For the economic assessment a three-tiered production/supply and consumption model is developed based on site specific levelized cost of electricity (LCOE) and other cost parameter to operate the model. Modeling results indicated the economic feasibility and advantage of a prosumer approach in a significant number of modeling scenarios. Additionally, a break-even analysis for the two approaches was undertaken to understand the sensitivity of individual input parameters.
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