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Search Results: 1 - 10 of 211095 matches for " Rebecca L Poole "
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Variability in Skin Prick Test Results Performed by Multiple Operators Depends on the Device Used
Rebecca L Werther, Sharon Choo, Katherine J Lee, Debra Poole, Katrina J Allen, Mimi LK Tang
World Allergy Organization Journal , 2012, DOI: 10.1097/wox.0b013e31827e6513
Abstract: We assessed the variability of measurements from 4 commonly used single-headed skin test devices when used by multiple operators and examined whether the variability in performance was different on the back compared with the forearm.Eight adult volunteer "operators" were trained in the use of 4 devices: Greer Pick, Quintip, Stallergenes Lancet, and Feather Lancet. Each operator performed a histamine skin prick test with all devices on the backs and forearms of 5 volunteer "receivers." Variability in results was assessed using a multilevel (random effects) regression model.After controlling for variation between users and receivers, the residual variability or "measurement error" was least for the Stallergenes Lancet, closely followed by the Quintip. The Greer Pick had the greatest variability. There was greater variability in measurements on the arm compared with the back.The devices using the "puncture" method (Stallergenes Lancet, Quintip) provide less variability in results than those using a "prick" method when carried out by multiple users (Greer Pick and Feather Lancet). Testing on the back also gives less variable results compared with the arm.
Analysis of wheat SAGE tags reveals evidence for widespread antisense transcription
Rebecca L Poole, Gary LA Barker, Kay Werner, Gaia F Biggi, Jane Coghill, J George Gibbings, Simon Berry, Jim M Dunwell, Keith J Edwards
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-475
Abstract: Examination of 71,930 Long SAGE tags generated from six libraries derived from two wheat genotypes grown under two different conditions suggested that SAGE is a reliable and reproducible technique for use in studying the hexaploid wheat transcriptome. However, our results also showed that in poorly annotated and/or poorly sequenced genomes, such as hexaploid wheat, considerably more information can be extracted from SAGE data by carrying out a systematic analysis of both perfect and "fuzzy" (partially matched) tags. This detailed analysis of the SAGE data shows first that while there is evidence of alternative polyadenylation this appears to occur exclusively within the 3' untranslated regions. Secondly, we found no strong evidence for widespread alternative splicing in the developing wheat grain transcriptome. However, analysis of our SAGE data shows that antisense transcripts are probably widespread within the transcriptome and appear to be derived from numerous locations within the genome. Examination of antisense transcripts showing sequence similarity to the Puroindoline a and Puroindoline b genes suggests that such antisense transcripts might have a role in the regulation of gene expression.Our results indicate that the detailed analysis of transcriptome data, such as SAGE tags, is essential to understand fully the factors that regulate gene expression and that such analysis of the wheat grain transcriptome reveals that antisense transcripts maybe widespread and hence probably play a significant role in the regulation of gene expression during grain development.With cereals constituting more than 60% of the world's dietary intake, the bread wheat Triticum aestivum is one of the most important crops in world agriculture [1,2]. Despite the high yields achieved in Europe there is still a real need to generate improved cultivars, as yield and flour quality can be dramatically affected by the environment. This need has become even greater in recent years with tight
Representing Bayesian Networks within Probabilistic Horn Abduction
David L. Poole
Computer Science , 2013,
Abstract: This paper presents a simple framework for Horn clause abduction, with probabilities associated with hypotheses. It is shown how this representation can represent any probabilistic knowledge representable in a Bayesian belief network. The main contributions are in finding a relationship between logical and probabilistic notions of evidential reasoning. This can be used as a basis for a new way to implement Bayesian Networks that allows for approximations to the value of the posterior probabilities, and also points to a way that Bayesian networks can be extended beyond a propositional language.
The use of conflicts in searching Bayesian networks
David L. Poole
Computer Science , 2013,
Abstract: This paper discusses how conflicts (as used by the consistency-based diagnosis community) can be adapted to be used in a search-based algorithm for computing prior and posterior probabilities in discrete Bayesian Networks. This is an "anytime" algorithm, that at any stage can estimate the probabilities and give an error bound. Whereas the most popular Bayesian net algorithms exploit the structure of the network for efficiency, we exploit probability distributions for efficiency; this algorithm is most suited to the case with extreme probabilities. This paper presents a solution to the inefficiencies found in naive algorithms, and shows how the tools of the consistency-based diagnosis community (namely conflicts) can be used effectively to improve the efficiency. Empirical results with networks having tens of thousands of nodes are presented.
A Framework for Decision-Theoretic Planning I: Combining the Situation Calculus, Conditional Plans, Probability and Utility
David L. Poole
Computer Science , 2013,
Abstract: This paper shows how we can combine logical representations of actions and decision theory in such a manner that seems natural for both. In particular we assume an axiomatization of the domain in terms of situation calculus, using what is essentially Reiter's solution to the frame problem, in terms of the completion of the axioms defining the state change. Uncertainty is handled in terms of the independent choice logic, which allows for independent choices and a logic program that gives the consequences of the choices. As part of the consequences are a specification of the utility of (final) states. The robot adopts robot plans, similar to the GOLOG programming language. Within this logic, we can define the expected utility of a conditional plan, based on the axiomatization of the actions, the uncertainty and the utility. The ?planning' problem is to find the plan with the highest expected utility. This is related to recent structured representations for POMDPs; here we use stochastic situation calculus rules to specify the state transition function and the reward/value function. Finally we show that with stochastic frame axioms, actions representations in probabilistic STRIPS are exponentially larger than using the representation proposed here.
Exploiting the Rule Structure for Decision Making within the Independent Choice Logic
David L. Poole
Computer Science , 2013,
Abstract: This paper introduces the independent choice logic, and in particular the "single agent with nature" instance of the independent choice logic, namely ICLdt. This is a logical framework for decision making uncertainty that extends both logic programming and stochastic models such as influence diagrams. This paper shows how the representation of a decision problem within the independent choice logic can be exploited to cut down the combinatorics of dynamic programming. One of the main problems with influence diagram evaluation techniques is the need to optimise a decision for all values of the 'parents' of a decision variable. In this paper we show how the rule based nature of the ICLdt can be exploited so that we only make distinctions in the values of the information available for a decision that will make a difference to utility.
Context-Specific Approximation in Probabilistic Inference
David L. Poole
Computer Science , 2013,
Abstract: There is evidence that the numbers in probabilistic inference don't really matter. This paper considers the idea that we can make a probabilistic model simpler by making fewer distinctions. Unfortunately, the level of a Bayesian network seems too coarse; it is unlikely that a parent will make little difference for all values of the other parents. In this paper we consider an approximation scheme where distinctions can be ignored in some contexts, but not in other contexts. We elaborate on a notion of a parent context that allows a structured context-specific decomposition of a probability distribution and the associated probabilistic inference scheme called probabilistic partial evaluation (Poole 1997). This paper shows a way to simplify a probabilistic model by ignoring distinctions which have similar probabilities, a method to exploit the simpler model, a bound on the resulting errors, and some preliminary empirical results on simple networks.
Transcriptome analysis of grain development in hexaploid wheat
Yongfang Wan, Rebecca L Poole, Alison K Huttly, Claudia Toscano-Underwood, Kevin Feeney, Sue Welham, Mike J Gooding, Clare Mills, Keith J Edwards, Peter R Shewry, Rowan AC Mitchell
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-121
Abstract: The transcriptome of developing caryopses from hexaploid wheat (Triticum aestivum, cv. Hereward) was determined using Affymetrix wheat GeneChip? oligonucleotide arrays which have probes for 55,052 transcripts. Of these, 14,550 showed significant differential regulation in the period between 6 and 42 days after anthesis (daa). Large changes in transcript abundance were observed which were categorised into distinct phases of differentiation (6–10 daa), grain fill (12–21 daa) and desiccation/maturation (28–42 daa) and were associated with specific tissues and processes. A similar experiment on developing caryopses grown with dry and/or hot environmental treatments was also analysed, using the profiles established in the first experiment to show that most environmental treatment effects on transcription were due to acceleration of development, but that a few transcripts were specifically affected. Transcript abundance profiles in both experiments for nine selected known and putative wheat transcription factors were independently confirmed by real time RT-PCR. These expression profiles confirm or extend our knowledge of the roles of the known transcription factors and suggest roles for the unknown ones.This transcriptome data will provide a valuable resource for molecular studies on wheat grain. It has been demonstrated how it can be used to distinguish general developmental shifts from specific effects of treatments on gene expression and to diagnose the probable tissue specificity and role of transcription factors.Cereals are of immense importance to humankind with over 2000 million tonnes being harvested annually and used for food, livestock feed and industrial raw materials. These uses exploit the reserves of starch and protein, which are deposited in the endosperm which accounts for about 80% of the mature grain. Hence, grain yield and end use quality are largely determined by thesize and composition of the endosperm.The endosperm is formed by a second fertilisation
Analogies for Teaching Mutant Allele Dominance Concepts  [PDF]
Rebecca L. Seipelt-Thiemann
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326133
Abstract: Analogies connect new and familiar concepts and ideas by providing a comfortable and known framework within which students can integrate new concepts. Use of analogies to aid understanding of abstract and/or complex ideas is commonly used in molecular sciences, such as genetics, molecular biology, and biochemistry. Five analogies for different mechanisms of mutant allele dominance, a seemingly counter-intuitive idea in genetics, were designed and assessed in an upper division undergraduate/masters level course. Each of the five mechanisms, haploinsufficiency, acquired function, poison product, increased activity, and inappropriate expression, was described in the context of a human disease and molecular mechanism and followed by a descriptive analogy which mirrored the molecular mechanism using real world items or a video clip. The majority of students reported increased interest, understanding, and engagement following the analogies, as well as decreased confusion.
Availability of Information on Reptile Health and Welfare from Stores Selling Reptiles  [PDF]
David L. Williams, Rebecca Jackson
Open Journal of Veterinary Medicine (OJVM) , 2016, DOI: 10.4236/ojvm.2016.63007
Abstract: The popularity of keeping reptiles such as snakes and lizards is ever increasing. The health and welfare of these animals depends on the knowledge and understanding of their environmental and nutritional needs. But where does a new owner of these species obtain such information? This study aims to investigate what information is available in pet shops and stores for the reptile owning public and how well this information is imparted. Our findings show that there is a lot of excellent advice on the husbandry of reptiles in some shops while others offer less advice. It is hoped that through this study areas of downfall on primary knowledge can be recognized so that all shops can aspire to the highest levels of information.
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