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Search Results: 1 - 10 of 300912 matches for " Kenneth J. McLeod "
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Developing an Evolutionary Algorithm to Search for an Optimal Multi-Mother Wavelet Packets Combination  [PDF]
Ohad Bar Siman Tov, J. David Schaffer, Kenneth J. McLeod
Journal of Biomedical Science and Engineering (JBiSE) , 2015, DOI: 10.4236/jbise.2015.87043
Abstract: The wavelet transform is a popular analysis tool for non-stationary data, but in many cases, the choice of the mother wavelet and basis set remains uncertain, particularly when dealing with physiological data. Furthermore, the possibility exists for combining information from numerous mother wavelets so as to exploit different features from the data. However, the combinatorics become daunting given the large number of basis sets that can be utilized. Recent work in evolutionary computation has produced a subset selection genetic algorithm specifically aimed at the discovery of small, high-performance, subsets from among a large pool of candidates. Our aim was to apply this algorithm to the task of locating subsets of packets from multiple mother wavelet decompositions to estimate cardiac output from chest wall motions while avoiding the computational cost of full signal reconstruction. We present experiments which show how a continuous assessment metric can be extracted from the wavelets coefficients, but the dual-objective nature of the algorithm (high accuracy with small feature sets) imposes a need to restrict the sensitivity of the continuous accuracy metric in order to achieve the small subset size desired. A possibly subtle tradeoff seems to be needed to meet the dual objectives.
Rectification of RF Fields in Load Dependent Coupled Systems: Application to Non-Invasive Electroceuticals  [PDF]
Sree N. Koneru, Charles R. Westgate, Kenneth J. McLeod
Journal of Biomedical Science and Engineering (JBiSE) , 2016, DOI: 10.4236/jbise.2016.92007
Abstract: Electroceuticals are medical devices that employ electric signals to alter the activity of specific nerve fibers to achieve therapeutic effects. The rapid growth of RF microelectronics has resulted in the development of very small, portable, and inexpensive shortwave and microwave radio frequency (RF) amplifiers, raising the possibility of utilizing these new RF technologies to develop non-contact electroceutical devices. However, the bio-electromagnetics literature suggests that beyond 10 MHz, RF fields cannot influence biological tissue, beyond simple heating, because effective demodulation mechanisms at these frequencies do not exist in the body. However, RF amplifiers operating at or near saturation have non-linear interactions with complex loads, and if body tissue creates a complex loading condition, the opportunity exists for the coupled system to produce non-linear effects, that is, the equivalent of demodulation may occur. Correspondingly, exposure of tissue to pulsed RF energy could result in the creation of low frequency demodulation components capable of influencing tissue activity. Here, we develop a one-dimen- sional, numerical simulation to investigate the complex loading conditions under which such demodulation could arise. Applying these results in a physical prototype device, we show that up to7.5% demodulation can be obtained for a 40 MHz RF field pulsed at 1 KHz. Implications for this research include the possibility of developing wearable, electromagnetic electroceutical de- vices.
Vibromyographic analysis of knee muscle imbalances in knee osteoarthritis  [PDF]
Kenneth McLeod, Sara Morley, Andrew Matsushima
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.54025
Abstract: Muscle imbalances are a well accepted cause of musculo-skeletal pain, yet clinicians lack a simple, non-invasive, and reproducible means to assess muscle effort during activities of daily living. To address this issue, we have been developing vibromyography (VMG) as a means to quantitatively assess muscle mechanical effort such that accurate muscle effort ratios can be determined in the clinic. In this study, VMG was used to characterize muscle imbalances in older adults with low-level knee pain while they performed step-up and step-down activities. In addition to determining whether VMG can identify the imbalances previously reported in individuals with knee pain, we address the question of whether these knee muscle imbalances were a likely cause of knee pain, or whether the imbalances represented a coping response for pre-existing knee pain. A population (N = 30) of 35 - 85 year old men and women with a total of 42 painful knees were assessed. Robust multiple step-wise regression analysis identified weak hip abductor muscle effort relative to hamstring muscle effort as the best predictor of knee pain (p = 0.00006), with weak vastus lateralis effort in eccentric contraction, relative to concentric contraction, being the second best predictor (p = 0.0003). Muscle imbalances were able to account for 40% of the variation in reported pain, and the observed pattern of increasing knee pain with increasing quadriceps strength during concentric contraction leads us to infer that the observed muscle imbalances are not the result of a protective action by the individual, but rather are a principle cause of the knee pain.
Argudas: arguing with gene expression information
Kenneth McLeod,Gus Ferguson,Albert Burger
Computer Science , 2010,
Abstract: In situ hybridisation gene expression information helps biologists identify where a gene is expressed. However, the databases that republish the experimental information are often both incomplete and inconsistent. This paper examines a system, Argudas, designed to help tackle these issues. Argudas is an evolution of an existing system, and so that system is reviewed as a means of both explaining and justifying the behaviour of Argudas. Throughout the discussion of Argudas a number of issues will be raised including the appropriateness of argumentation in biology and the challenges faced when integrating apparently similar online biological databases.
Do Genetic Diversity Effects Drive the Benefits Associated with Multiple Mating? A Test in a Marine Invertebrate
Laura McLeod, Dustin J. Marshall
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006347
Abstract: Background Mothers that mate with multiple males often produce higher quality offspring than mothers that mate with a single male. By engaging in polyandry, mothers may increase their chances of mating with a compatible male or promote sperm competition - both of which act to increase maternal fitness via the biasing of the paternity of offspring. Surprisingly, mating with multiple males, can carry benefits without biasing paternity and may be due simply to differences in genetic diversity between monandrous and polyandrous clutches but role of genetic diversity effects in driving the benefits of polyandry remains poorly tested. Disentangling indirect, genetic benefits from genetic diversity effects is challenging but crucial if we are to understand the selection pressures acting to promote polyandry. Methodology/Principal Findings Here, we examine the post-fertilisation benefits of accessing the sperm of multiple males in an externally fertilising polychaete worm. Accessing the sperm of multiple males increases offspring performance but this benefit was driven entirely by genetic diversity effects and not by the biasing of paternity at fertilisation. Conclusions/Significance Previous studies on polyandry should be interpreted cautiously as genetic diversity effects alone can explain the benefits of polyandry yet these diversity effects may be difficult to disentangle from other mechanisms. We suggest that future studies use a modified experimental design in order to discriminate between genetic diversity effects and indirect, genetic benefits.
Visualization of gene expression information within the context of the mouse anatomy
Andy Taylor,Kenneth McLeod,Chris Armit,Richard Baldock,Albert Burger
Computer Science , 2014,
Abstract: Background: The eMouse Atlas of Gene Expression (EMAGE) is an online resource that publishes the results of in situ gene expression experiments on the developmental mouse. The resource provides comprehensive search facilities, but few analytical tools or visual mechanisms for navigating the data set. To deal with the missing visual navigation, this paper explores the application of sunburst and icicle visualizations within EMAGE. Results: A prototype solution delivered a simple user interface that helps the user query EMAGE and generate a sunburst/icicle diagram. An evaluation featuring test subjects from the EMAGE staff studied the visualizations and provided a range of suggested improvements. Moreover the evaluation discovered that in addition to providing a visual means of walking through the data, when grouped, the sunburst delivers an interactive overview that assists with analysing sets of related genes. Conclusions: The sunburst and icicle visualizations have been shown to be effective tools for summarising gene expression data. The sunburst with its space saving radial layout was found especially useful for providing an overview of gene families or pathways. Work is ongoing to integrate these visualizations into EMAGE.
Hyperbolic Coxeter Pyramids  [PDF]
John Mcleod
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.31010
Abstract:

Hyperbolic Coxeter polytopes are defined precisely by combinatorial type. Polytopes in hyperbolic n-space with n + p faces that have the combinatorial type of a pyramid over a product of simplices were classified by Tumarkin for small p. In this article we generalise Tumarkins methods and find the remaining hyperbolic Coxeter pyramids.

Education and training for records management in the electronic environment - the (re)search for an appropriate model. Professional development, Training, Education, Models, Records management
McLeod J.,Hare C.,Johare R.
Information Research: an international electronic journal , 2004,
Abstract: Managing records in the e-environment constitutes a complex and challenging strategic issue for all organizations because IT systems shape business operations and the nature and management of the records they generate. IT personnel, administrators, archivists, records creators and users, as well as records managers, must work in partnership to ensure the authenticity, reliability, integrity, and ongoing usability of records. Education and training provision must evolve to fulfil the needs of all of these players in this complex environment. Everyone needs a macro-level understanding, combined with micro-level knowledge and practical skills, determined by their role, responsibility and level of systems interface. This matrix of horizontal and vertical mappings defines a pathway tailored to the individual's recordkeeping role. The requirement is holistic not atomistic, because it is integrated with the business processes. This study critically evaluates existing initiatives and initial results of a doctoral study searching for a best practice model.
The Effects of Starbursts and Low-Surface-Brightness Galaxies on Faint Galaxy Models
B. A. McLeod,M. J. Rieke
Physics , 1995, DOI: 10.1086/176515
Abstract: We present models predicting the magnitude, redshift, and color distributions of field galaxies. We explore whether a fading starburst scenario can account for the observations of faint blue galaxies. We marginally rule out a starburst scenario with a local IMF because the models predict too many nearby faint galaxies that are not observed. A burst model with a truncated IMF reproduces the counts and redshift distributions well but produces too blue a population. We show that surface brightness selection has a significant effect on the distributions. In particular, adding a population of low-surface brightness galaxies, known to exist locally, can explain the counts for $B_J<23$. They do not, however, account for the steepness of the counts at fainter magnitudes. Finally we show that the colors of galaxies in a $K$-band selected sample are too blue to be consistent with a constant star-formation rate, passive-evolution model.
Existence of the Solution for the 't Hooft-Polyakov Monopole
J. Bryce McLeod,Chie Bing Wang
Physics , 1999,
Abstract: In this paper we give a mathematical proof of the existence of the time independent and spherically symmetric solution to the 't Hooft-Polyakov model of magnetic monopole by using 2D-shooting method.
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