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Search Results: 1 - 10 of 401530 matches for " M. Thomson "
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Credentialing for radiology
M Street,KR Thomson
Biomedical Imaging and Intervention Journal , 2008, DOI: 10.2349/biij.4.1.e14
Development of Cortical GABAergic Innervation
Alex M. Thomson
Frontiers in Cellular Neuroscience , 2011, DOI: 10.3389/fncel.2011.00014
Abstract: The mature neocortex contains many different classes of GABAergic inhibitory interneurons, distributed, with some degree of selectivity, through six layers, and through many different regions. Some of the events in the early lives of these neurones that may determine their ultimate destination, their maturation and their selective innervation of targets appropriate for each subtype, are discussed. Both time and place of birth influence the class of interneuron that an early post-mitotic interneuronal precursor will become, driven by the selective expression of different combinations of transcription factors in different regions of their birth places in the ganglionic eminence and ventricular zone. The long distance migration of these precursors along tangential routes in marginal, subventricular, and intermediate zones and their final radial movement, into the developing cortex, is regulated by chemical cues, both attractant and repellent. Once they arrive at their final destination, they must integrate into the developing circuitry. As they mature within the cortex, their axons grow and branch in highly specific patterns that may be partially determined by the genetic blueprint for each interneuronal class and partly by the environment in which they find themselves. Finally, as each interneuron class begins to form synapses with only certain postsynaptic targets, cell–cell recognition, most probably via protein–protein interactions across the synaptic cleft, facilitate the formation of appropriate synapses.
Particle Flow Calorimetry and the PandoraPFA Algorithm
M. A. Thomson
Physics , 2009, DOI: 10.1016/j.nima.2009.09.009
Abstract: The Particle Flow (PFlow) approach to calorimetry promises to deliver unprecedented jet energy resolution for experiments at future high energy colliders such as the proposed International Linear Collider (ILC). This paper describes the PandoraPFA particle flow algorithm which is then used to perform the first systematic study of the potential of high granularity PFlow calorimetry. For simulated events in the ILD detector concept, a jet energy resolution of sigma_E/E < 3.8 % is achieved for 40-400 GeV jets. This result, which demonstrates that high granularity PFlow calorimetry can meet the challenging ILC jet energy resolution goals, does not depend strongly on the details of the Monte Carlo modelling of hadronic showers. The PandoraPFA algorithm is also used to investigate the general features of a collider detector optimised for high granularity PFlow calorimetry. Finally, a first study of the potential of high granularity PFlow calorimetry at a multi-TeV lepton collider, such as CLIC, is presented.
Particle Flow Calorimetry at the ILC
M. A. Thomson
Physics , 2006, DOI: 10.1007/s12043-007-0236-9
Abstract: One of the most important requirements for a detector at the ILC is good jet energy resolution. It is widely believed that the particle flow approach to calorimetry is the key to achieving the goal of 0.3/sqrt(E[GeV]). This paper describes the current performance of the PandoraPFA particle flow algorithm. For 45 GeV jets in the Tesla TDR detector concept, the ILC jet energy resolution goal is reached. At higher energies the jet energy resolution becomes worse and can be described by the empirical expression: sigma_E/E ~ 0.265/sqrt(E[GeV]) + 1.2x10^{-4}E[GeV].
Progress with Particle Flow Calorimetry
M. A. Thomson
Physics , 2007,
Abstract: One of the most important requirements for a detector at the ILC is good jet energy resolution. It is widely believed that the particle flow approach to calorimetry is the key to achieving the ILC goal of a di-jet invariant mass resolution sigma_m/m < Gamma_Z/m_Z. This paper describes the current performance of the PandoraPFA particle flow algorithm. For simulated light quark jets in the Tesla TDR detector, the jet energy resolution achieved is better than sigma_E/E ~ 3.4% for jet energies in the range 45-250 GeV. This represents the first demonstration that Particle Flow Calorimetry can reach the ILC jet energy resolution goals.
Effects of scanning sensitivity and multiple scan algorithms on microarray data quality
Andrew Williams, Errol M Thomson
BMC Bioinformatics , 2010, DOI: 10.1186/1471-2105-11-127
Abstract: Of the individual scans, the low scan exhibited the lowest background signal, the highest signal-to-noise ratio, and equivalent reproducibility to the medium and high scans. Most multiple scan approaches increased the range of probe intensities compared to the individual scans, but did not increase the dynamic range (the proportion of useable data). Approaches displayed striking differences in the background signal and signal-to-noise ratio. However, increased probe intensity range and improved signal-to-noise ratios did not necessarily correlate with improved reproducibility. Importantly, for one multiple scan method that combined 3 scans, reproducibility was significantly improved relative to individual scans and all other multiple scan approaches. The same method using 2 scans yielded significantly lower reproducibility, attributable to a lack-of-fit of the statistical model.Our data indicate that implementation of a suitable multiple scan approach can improve reproducibility, but that model validation is critical to ensure accurate estimates of probe intensity.DNA microarrays allow analysis of genome-wide gene expression. While an entire transcriptome can theoretically be quantified on a single array, in practice a proportion of probes analysed will not provide quantifiable signal. For example, when scanning any complex biological sample hybridized to a microarray, low copy number genes may emit low fluorescence signals not detectable above background; conversely, high copy number genes may emit fluorescence signals that are saturated. To maximize the amount of data acquired from a single microarray scan, the user attempts to generate a scan that spans the entire intensity range by selecting appropriate photo-multiplier tube (PMT) settings. In selecting the PMT of the scanner, the user has two major concerns: quantification error associated with image analysis (e.g., distinguishing signal from background) and signal saturation associated with the selection of sc
Distribution of interneurones in the CA2 region of the rat hippocampus.
Alex M. Thomson,Audrey Mercer
Frontiers in Neuroanatomy , 2014, DOI: 10.3389/fnana.2014.00104
Abstract: The CA2 region of the mammalian hippocampus is a unique region with its own distinctive properties, inputs and pathologies. Disruption of inhibitory circuits in this region appears to be linked with the pathology of specific psychiatric disorders, promoting interest in its local circuitry, its role in hippocampal function and its dysfunction in disease. In previous studies, CA2 interneurones, including a novel subclass of CA2 dendrite-preferring interneurones that has not been identified in other CA regions, have been shown to display physiological, synaptic and morphological properties unique to this sub-field and may therefore play a crucial role in the hippocampal circuitry. The distributions of immuno-labelled interneurones in dorsal CA2 were studied and compared with those of interneurones in CA1 and CA3. Like those in CA1 and CA3, the somata of CA2 parvalbumin-immunoperoxidase-labeled interneurones were located primarily in Stratum Pyramidale (SP) and Stratum Oriens (SO), with very few cells in Stratum Radiatum (SR) and none in Stratum Lacunosum Moleculare (SLM). There was, however, a greater proportion of GAD-positive cells were immunopositive for PV in SP in CA2 than in CA1 or CA3. CA2 SP also contained a larger density of somatostatin-, calbindin- and VIP-immunopositive somata than CA1 and/or CA3. Like those in CA1 and CA3, CCK-immunopositive somata in CA2 were mostly located in SR. Reelin- and NPY- immunolabelled cell bodies were located in all layers of the three CA regions. However, a higher density of Reelin-positive somata was found in SP and SR of CA2 than in CA1 or CA3.
Functional maps of neocortical local circuitry
Alex M. Thomson,Christophe Lamy
Frontiers in Neuroscience , 2007, DOI: 10.3389/neuro.
Abstract: This review aims to summarize data obtained with different techniques to provide a functional map of the local circuit connections made by neocortical neurones, a reference for those interested in cortical circuitry and the numerical information required by those wishing to model the circuit. A brief description of the main techniques used to study circuitry is followed by outline descriptions of the major classes of neocortical excitatory and inhibitory neurones and the connections that each layer makes with other cortical and subcortical regions. Maps summarizing the projection patterns of each class of neurone within the local circuit and tables of the properties of these local circuit connections are provided.
Spectral Energy Distribution of z>1 Type Ia Supernova Hosts in GOODS: Constraints on Evolutionary Delay and the Initial Mass Function
M. G. Thomson,R. Chary
Physics , 2010, DOI: 10.1088/0004-637X/731/1/72
Abstract: We identify a sample of 22 host galaxies of Type Ia Supernovae (SNe Ia) at redshifts 0.95
Hemopneumotórax espontaneo: uma rara entidade clínica
Jornal de Pneumologia , 2000, DOI: 10.1590/S0102-35862000000500008
Abstract: spontaneous hemopneumothorax with massive bleeding is considered a rare complication of spontaneous pneumothorax. the authors describe two patients with acute chest pain and dyspnea; the chest x-ray showed pneumothorax and pleural effusion. the two cases were submitted to thoracic drainage and presented important bleeding; thoracotomy was performed and in the first case an aberrant vessel was found, and in the second case the source of bleeding was rupture of pleural adherence. the post-operative evolution had no incidents in either case.
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