oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 2 )

2019 ( 286 )

2018 ( 408 )

2017 ( 390 )

Custom range...

Search Results: 1 - 10 of 339892 matches for " David J. Lythgoe "
All listed articles are free for downloading (OA Articles)
Page 1 /339892
Display every page Item
A Pragmatic Approach to Coping with Matrix Effects during ICP-MS Analysis of Trace Elements in Silicate Rocks and Calibration of REE Interferences  [PDF]
C. Michael B. Henderson, Paul R. Lythgoe, Karen J. Theis
Journal of Geoscience and Environment Protection (GEP) , 2019, DOI: 10.4236/gep.2019.73005
Abstract: Operating an Agilent 7700X ICP-MS spectrometer under robust plasma conditions (1550 W) with a He-filled octopole collision cell and analysing solutions (<2000 μg·g?1 total dissolved solids) still suffered analyte peak suppression due to matrix effects. International reference rocks BCR-1, BHVO-1, AGV-1, G-2 and BCR-2 all showed count rate reductions for 36 elements (mass range 7Li to 238U) averaging ~10% but with no dependence on isotope mass. Use of an internal standard (103Rh) and/or using a ten-fold dilution of sample solutions reduced these effects but problems with reduced count rates combined with larger errors for some elements introduced other problems. The best approach was to normalise the count rates for each element in the other samples against those for BCR-1 as an external standard; thus the count suppression due to the matrix effect is corrected for each individual element. This approach provides standardization “traceability” in line with the ERM ISO/IEC requirement. Experiments are also reported on quantifying the proportions of Ba and selected REE oxide/hydroxide components versus parent isotopes (XO/X and XOH/X). This information is essential for correcting peak interferences on higher mass number REE for the rock samples, and equations are developed to use measured CeO/Ce and CeOH/Ce ratios to predict such values for any other member of the REE suite. Concentrations obtained show excellent agreement with recommended values for the international reference materials especially for the REE. Robust data are also provided for two other standard rocks: nepheline syenite STM-1 and quartz syenite CAAS-1; the latter shows exceptional enrichments of Zr, REE, Th, and U.
Frontal GABA Levels Change during Working Memory
Lars Michels, Ernst Martin, Peter Klaver, Richard Edden, Fernando Zelaya, David J. Lythgoe, Rafael Lüchinger, Daniel Brandeis, Ruth L. O’Gorman
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031933
Abstract: Functional neuroimaging metrics are thought to reflect changes in neurotransmitter flux, but changes in neurotransmitter levels have not been demonstrated in humans during a cognitive task, and the relationship between neurotransmitter dynamics and hemodynamic activity during cognition has not yet been established. We evaluate the concentration of the major inhibitory (GABA) and excitatory (glutamate + glutamine: Glx) neurotransmitters and the cerebral perfusion at rest and during a prolonged delayed match-to-sample working memory task. Resting GABA levels in the dorsolateral prefrontal cortex correlated positively with the resting perfusion and inversely with the change in perfusion during the task. Further, only GABA increased significantly during the first working memory run and then decreased continuously across subsequent task runs. The decrease of GABA over time was paralleled by a trend towards decreased reaction times and higher task accuracy. These results demonstrate a link between neurotransmitter dynamics and hemodynamic activity during working memory, indicating that functional neuroimaging metrics depend on the balance of excitation and inhibition required for cognitive processing.
EL DESARROLLO DEL CONCEPTO DE TESTIMONIO EN PAUL RICOEUR
Lythgoe,Esteban;
Eidos , 2008,
Abstract: this paper tries to show that there has been an evolution in paul ricoeur's concept of testimony and that also his first juridical definition is different from others of the same origin. to determine this point we will compare his definition with c.a.j. coady's. we will try to explain the motives, implications and limitations of its differences. then it will be established that in remembering, history and oblivion the philosopher leaves the juridical concept of testimony, which main issues are to be a declaration inside a debate, and prefers an other one that define it as a dialogical natural institution. our hypothesis is that this change was not due to phenomenical but to contextual causes.
Pasado y presente en Ricoeur y de Certeau: Algunas consideraciones
Lythgoe,Esteban;
T?3picos , 2009,
Abstract: this paper studies the way in which ricoeur and de certeau conceives the relationship between historical narration and past. its hypothesis is that there has been a change in ricoeur's position between time and narrative and memory, history and oblivion. in the first book the articulation between historical narration and past is articulated by the plot. in the second one, the concept of event makes his analysis more similar to de certeau's. we discuss ricoeur's critic to de certeau in time and narrative and sustain that memory, history and oblivion. is not affected by this critic thanks to the concept of representation.
?Una superación de los límites de la representación? La reelaboración del debate en Frank Ankersmit y su recurso al testimonio
Lythgoe,Esteban;
Revista latinoamericana de filosof?-a , 2010,
Abstract: this paper analyses frank ankersmit's interpretation of the discussion on the limits of representation and his proposal to avoid it by using the testimony of the survivors of the holocaust. it is sustained that his answer to this discussion if unsatisfactory due both to internal inconsistencies and its inappropriate consequences. its internal limitations will show that the problem does not lie in the given answer but in the elaboration of the debate. on the other side, the reason of our interest in the external difficulties is that it does not only affect to ankersmit's proposal but to every one that gives more importance to the survivers' testimonies than to the historical representations.
Pasado y presente en Ricoeur y de Certeau: Algunas consideraciones
Esteban Lythgoe
T?3picos , 2009,
Abstract: El presente artículo compara el modo en que Ricoeur y de Certeau conciben la relación entre el escrito histórico y el pasado. Se sostiene que existe una importante modificación en el pensamiento de Ricoeur sobre esta cuestión en el período comprendido entre Tiempo y narración y La memoria, la historia, el olvido. En el primero, la articulación entre narración histórica y pasado se produce en la puesta en intriga mientras que la segunda vuelve a una concepción de la historia basada en el acontecimiento, cambio que acerca al filósofo al pensamiento de Certeau. Seguidamente, matizamos la crítica que el filósofo le realizara a de Certeau en Tiempo y narración acerca de su tesis acerca de que la narración histórica es distinta del pasado. Por último, concluimos justificando nuestra tesis de que el desarrollo de La memoria, la historia, el olvido logra salvarse de esta crítica gracias al uso que Ricoeur hace del concepto de representación. This paper studies the way in which Ricoeur and de Certeau conceives the relationship between historical narration and past. Its hypothesis is that there has been a change in Ricoeur's position between Time and Narrative and Memory, History and Oblivion. In the first book the articulation between historical narration and past is articulated by the plot. In the second one, the concept of event makes his analysis more similar to de Certeau's. We discuss Ricoeur's critic to de Certeau in Time and Narrative and sustain that Memory, History and Oblivion. is not affected by this critic thanks to the concept of representation.
Una superación de los límites de la representación? La reelaboración del debate en Frank Ankersmit y su recurso al testimonio
Esteban Lythgoe
Revista Latinoamericana de Filosofía , 2010,
Abstract: El presente artículo analiza el replanteo de Frank Ankersmit del debate en torno a los límites de la representación y su propuesta de recurrir al testimonio de los sobrevivientes del Holocausto. Se sostiene que su respuesta a la pregunta reelaborada resulta insatisfactoria tanto por inconsistencias internas como porque sus consecuencias son inapropiadas. Las limitaciones internas pondrán de manifiesto que el problema no reside en el tipo de respuesta dada sino en la reelaboración del debate. Por su parte, nuestro interés en las dificultades externas se debe a que no sólo afectan al filósofo tematizado sino a todos aquellos que privilegien los testimonios de los sobrevivientes por sobre las representaciones históricas. This paper analyses Frank Ankersmit's interpretation of the discussion on the limits of representation and his proposal to avoid it by using the testimony of the survivors of the Holocaust. It is sustained that his answer to this discussion if unsatisfactory due both to internal inconsistencies and its inappropriate consequences. Its internal limitations will show that the problem does not lie in the given answer but in the elaboration of the debate. On the other side, the reason of our interest in the external difficulties is that it does not only affect to Ankersmit's proposal but to every one that gives more importance to the survivers' testimonies than to the historical representations.
EL DESARROLLO DEL CONCEPTO DE TESTIMONIO EN PAUL RICOEUR
Esteban Lythgoe
Eidos , 2008,
Abstract: El objetivo del presente artículo consiste en sostener que ha habido una evolución en el concepto de testimonio de Paul Ricoeur y que incluso su primera definición jurídica se diferencia de otras de la misma raíz. Para establecer este último punto se compara su definición con de C.A.J. Coady. Se intentará dar cuenta de los motivos, implicaciones y limitaciones de sus diferencias. Seguidamente, se afirma que en La memoria, la historia, el olvido el filósofo abandona el concepto jurídico de testimonio, caracterizado como una declaración enmarcada en un debate, para inclinarse por otro que lo define como una institución natural dialógica. Nuestra hipótesis es que dicho cambio fue debido no a causas fenoménicas sino contextuales.
Mutation of the Diamond-Blackfan Anemia Gene Rps7 in Mouse Results in Morphological and Neuroanatomical Phenotypes
Dawn E. Watkins-Chow,Joanna Cooke,Ruth Pidsley,Andrew Edwards,Rebecca Slotkin,Karen E. Leeds,Raymond Mullen,Laura L. Baxter,Thomas G. Campbell,Marion C. Salzer,Laura Biondini,Gretchen Gibney,Fran?oise Phan Dinh Tuy,Jamel Chelly,H. Douglas Morris,Johannes Riegler,Mark F. Lythgoe,Ruth M. Arkell,Fabrizio Loreni,Jonathan Flint,William J. Pavan equal contributor ,David A. Keays equal contributor
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003094
Abstract: The ribosome is an evolutionarily conserved organelle essential for cellular function. Ribosome construction requires assembly of approximately 80 different ribosomal proteins (RPs) and four different species of rRNA. As RPs co-assemble into one multi-subunit complex, mutation of the genes that encode RPs might be expected to give rise to phenocopies, in which the same phenotype is associated with loss-of-function of each individual gene. However, a more complex picture is emerging in which, in addition to a group of shared phenotypes, diverse RP gene-specific phenotypes are observed. Here we report the first two mouse mutations (Rps7Mtu and Rps7Zma) of ribosomal protein S7 (Rps7), a gene that has been implicated in Diamond-Blackfan anemia. Rps7 disruption results in decreased body size, abnormal skeletal morphology, mid-ventral white spotting, and eye malformations. These phenotypes are reported in other murine RP mutants and, as demonstrated for some other RP mutations, are ameliorated by Trp53 deficiency. Interestingly, Rps7 mutants have additional overt malformations of the developing central nervous system and deficits in working memory, phenotypes that are not reported in murine or human RP gene mutants. Conversely, Rps7 mouse mutants show no anemia or hyperpigmentation, phenotypes associated with mutation of human RPS7 and other murine RPs, respectively. We provide two novel RP mouse models and expand the repertoire of potential phenotypes that should be examined in RP mutants to further explore the concept of RP gene-specific phenotypes.
Rapid assessment of myocardial infarct size in rodents using multi-slice inversion recovery late gadolinium enhancement CMR at 9.4T
Anthony N Price, King K Cheung, Shiang Y Lim, Derek M Yellon, Derek J Hausenloy, Mark F Lythgoe
Journal of Cardiovascular Magnetic Resonance , 2011, DOI: 10.1186/1532-429x-13-44
Abstract: Here we present a fast and robust protocol for assessing LGE in small animals using a multi-slice IR gradient echo sequence for efficient assessment of LGE. An additional Look-Locker sequence was used to assess the optimum inversion point on an individual basis and to determine most appropriate gating points for both rat and mouse. The technique was applied to two preclinical scenarios: i) an acute (2 hour) reperfused model of MI in rats and ii) mice 2 days following non-reperfused MI.LGE images from all animals revealed clear areas of enhancement allowing for easy volume segmentation. Typical inversion times required to null healthy myocardium in rats were between 300-450 ms equivalent to 2-3 R-waves and ~330 ms in mice, typically 3 R-waves following inversion. Data from rats was also validated against triphenyltetrazolium chloride staining and revealed close agreement for infarct size.The LGE protocol presented provides a reliable method for acquiring images of high contrast and quality without excessive scan times, enabling higher throughput in experimental studies requiring reliable assessment of MI.Cardiovascular magnetic resonance (CMR) has emerged as a valuable tool in the field of small animal cardiovascular research [1-6]. However, many of the CMR techniques that are now used as standard in the clinical setting remain a significant challenge to implement in small animals especially at high field [6], where relatively few optimised protocols are available as standard on experimental systems. One such technique, regarded as the gold standard for assessing myocardial infarction (MI) in patients [7], is late gadolinium enhancement (LGE) CMR. The extent of the LGE region is typically assessed using an inversion recovery (IR) breath-hold sequence, which can be readily applied to larger animals used in cardiovascular research [8,9]. When it comes to assessing LGE in small animals, such as rat and mouse, these methods become difficult to implement due to the rapid
Page 1 /339892
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.