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Search Results: 1 - 10 of 345146 matches for " D. G. FitzGerald "
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Mitsch's order and inclusion for binary relations and partitions
D. G. FitzGerald
Mathematics , 2012,
Abstract: Mitsch's natural partial order on the semigroup of binary relations is here characterised by equations in the theory of relation algebras. The natural partial order has a complex relationship with the compatible partial order of inclusion, which is explored by means of a sublattice of the lattice of preorders on the semigroup. The corresponding sublattice for the partition monoid is also described.
A Presentation for the Dual Symmetric Inverse Monoid
David Easdown,James East,D. G. FitzGerald
Mathematics , 2007,
Abstract: The dual symmetric inverse monoid $\mathscr{I}_n^*$ is the inverse monoid of all isomorphisms between quotients of an $n$-set. We give a monoid presentation of $\mathscr{I}_n^*$ and, along the way, establish criteria for a monoid to be inverse when it is generated by completely regular elements.
Overt Mycobacterium avium subsp. paratuberculosis Infection: An Infrequent Occurrence in Archived Tissue from False TB Reactor Cattle in Michigan, USA
Scott D. Fitzgerald,Steven R. Bolin,Kathryn G. Boland,Ailam Lim,John B. Kaneene
Veterinary Medicine International , 2011, DOI: 10.4061/2011/910738
Abstract: The objective of this study was to retrospectively determine whether or not cattle from the state of Michigan which were classified as bovine tuberculosis reactors, based on currently approved field and laboratory testing methods, were overtly infected with Mycobacterium avium subsp. paratuberculosis (MAP). Included in this study were 384 adult cattle submitted to the Diagnostic Center for Population and Animal Health over a seven-year period. Cattle were tested utilizing standard methods to confirm that all cattle were lesion and culture negative for infection with Mycobacterium bovis at postmortem examination. Retrospective analysis of formalin-fixed, paraffin-embedded sections of ileum and ileocecal lymph node were evaluated by histopathology, acid-fast staining, and PCR assays to detect MAP. Overall, only 1.04 percent of cattle showed overt infection with MAP on visual examination of sections of ileum and/or ileo-cecal lymph node. This increased slightly to 2.1 percent of cattle likely infected with MAP after additional testing using a PCR assay. Based on these results, we found no evidence that overt infection with MAP plays a major role in the false tuberculosis reactor test results for cattle examined in this study. 1. Introduction The identification of bovine tuberculosis (TB) in white-tailed deer in Michigan in 1994, and the subsequent identification of TB in cattle, has resulted in a long-term surveillance program for TB in cattle [1]. To date, 50 cattle herds have been found in Michigan that contained one or more M. bovis infected animals [2]. Thousands of cattle have been tested as suspect reactors on the caudal fold test (CFT) and comparative cervical test (CCT) or gamma interferon assay (γ-IFN), but only 138 cattle have been found infected with M. bovis. The large number of cattle found as false-positive reactors on field and laboratory tests, compared with the relatively small number of cattle eventually diagnosed as TB positive, is a reflection of the specificity of the currently approved antemortem diagnostic procedures when disease prevalence is low. Development of improved antemortem screening tests for detection of cattle and other species infected with Mycobacterium bovis (M. bovis), the causal agent of bovine tuberculosis, has been the subject of recent research [3–10]. This activity is driven by the less than optimal sensitivity and specificity of currently approved diagnostic tests for antemortem detection of TB. Diagnostic tests currently approved to screen for bovine tuberculosis in the USA include the CFT, the CCT, and the
Chemical Interactions and Their Role in the Microphase Separation of Block Copolymer Thin Films
Richard A. Farrell,Thomas G. Fitzgerald,Dipu Borah,Justin D. Holmes,Michael A. Morris
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10093671
Abstract: The thermodynamics of self-assembling systems are discussed in terms of the chemical interactions and the intermolecular forces between species. It is clear that there are both theoretical and practical limitations on the dimensions and the structural regularity of these systems. These considerations are made with reference to the microphase separation that occurs in block copolymer (BCP) systems. BCP systems self-assemble via a thermodynamic driven process where chemical dis-affinity between the blocks driving them part is balanced by a restorative force deriving from the chemical bond between the blocks. These systems are attracting much interest because of their possible role in nanoelectronic fabrication. This form of self-assembly can obtain highly regular nanopatterns in certain circumstances where the orientation and alignment of chemically distinct blocks can be guided through molecular interactions between the polymer and the surrounding interfaces. However, for this to be possible, great care must be taken to properly engineer the interactions between the surfaces and the polymer blocks. The optimum methods of structure directing are chemical pre-patterning (defining regions on the substrate of different chemistry) and graphoepitaxy (topographical alignment) but both centre on generating alignment through favourable chemical interactions. As in all self-assembling systems, the problems of defect formation must be considered and the origin of defects in these systems is explored. It is argued that in these nanostructures equilibrium defects are relatively few and largely originate from kinetic effects arising during film growth. Many defects also arise from the confinement of the systems when they are ‘directed’ by topography. The potential applications of these materials in electronics are discussed.
Ferromagnetism in substituted zinc oxide
M. Venkatesan,C. B. Fitzgerald,J. G. Lunney,J. M. D. Coey
Physics , 2004, DOI: 10.1103/PhysRevLett.93.177206
Abstract: Room-temperature ferromagnetism is observed in (110) oriented ZnO films containing 5 at % of Sc, Ti, V, Fe, Co or Ni, but not Cr, Mn or Cu ions. There are large moments, 1.9 and 0.5 muB/atom for Co- and Ti-substituted oxides, respectively. Sc-substituted ZnO shows also a moment of 0.3 muB/Sc. Magnetization is very anisotropic, with variations of up to a factor three depending on the orientation of the applied field relative to the R-cut sapphire substrates. Results are interpreted in terms of a spin-split donor impurity band model, which can account for ferromagnetism in insulating or conducting high-k oxides with concentrations of magnetic ions that lie far below the percolation threshold. The variation of the ferromagnetism with oxygen pressure used during film growth is evidence of a link between ferromagnetism and defect concentration.
Siete alternativas a la medicina basada en la evidencia
Isaac D.,Fitzgerald D.
Revista del Hospital Materno Infantil Ramón Sardá , 2002,
Hubble Space Telescope Optical Imaging of the Eroding Debris Disk HD 61005
H. L. Maness,P. Kalas,K. M. G. Peek,E. I. Chiang,K. Scherer,M. P. Fitzgerald,James R. Graham,D. C. Hines,G. Schneider,S. A. Metchev
Physics , 2009, DOI: 10.1088/0004-637X/707/2/1098
Abstract: We present Hubble Space Telescope optical coronagraphic polarization imaging observations of the dusty debris disk HD 61005. The scattered light intensity image and polarization structure reveal a highly inclined disk with a clear asymmetric, swept back component, suggestive of significant interaction with the ambient interstellar medium. The combination of our new data with the published 1.1 micron discovery image shows that the grains are blue scattering with no strong color gradient as a function of radius, implying predominantly sub-micron sized grains. We investigate possible explanations that could account for the observed swept back, asymmetric morphology. Previous work has suggested that HD 61005 may be interacting with a cold, unusually dense interstellar cloud. However, limits on the intervening interstellar gas column density from an optical spectrum of HD 61005 in the Na I D lines render this possibility unlikely. Instead, HD 61005 may be embedded in a more typical warm, low-density cloud that introduces secular perturbations to dust grain orbits. This mechanism can significantly distort the ensemble disk structure within a typical cloud crossing time. For a counterintuitive relative flow direction--parallel to the disk midplane--we find that the structures generated by these distortions can very roughly approximate the HD 61005 morphology. Future observational studies constraining the direction of the relative interstellar medium flow will thus provide an important constraint for future modeling. Independent of the interpretation for HD 61005, we expect that interstellar gas drag likely plays a role in producing asymmetries observed in other debris disk systems, such as HD 15115 and Delta-Velorum.
Exposures to lead require ongoing vigilance
Mangas Sotirios,Fitzgerald D. James
Bulletin of the World Health Organization , 2003,
Regional Differences in Susceptibility to Hypoxic-Ischemic Injury in the Preterm Brain: Exploring the Spectrum from White Matter Loss to Selective Grey Matter Injury in a Rat Model
D. B. Selip,L. L. Jantzie,M. Chang,M. C. Jackson,E. C. Fitzgerald,G. Boll,A. Murphy,F. E. Jensen
Neurology Research International , 2012, DOI: 10.1155/2012/725184
Abstract: Models of premature brain injury have largely focused on the white matter injury thought to underlie periventricular leukomalacia (PVL). However, with increased survival of very low birth weight infants, injury patterns involving grey matter are now recognized. We aimed to determine how grey matter lesions relate to hypoxic-ischemic- (HI) mediated white matter injury by modifying our rat model of PVL. Following HI, microglial infiltration, astrocytosis, and neuronal and axonal degeneration increased in a region-specific manner dependent on the severity of myelin loss in pericallosal white matter. The spectrum of injury ranged from mild, where diffuse white matter abnormalities were dominant and were associated with mild axonal injury and local microglial activation, to severe HI injury characterized by focal MBP loss, widespread neuronal degeneration, axonal damage, and gliosis throughout the neocortex, caudate putamen, and thalamus. In sum, selective regional white matter loss occurs in the preterm rat concomitantly with a clinically relevant spectrum of grey matter injury. These data demonstrate an interspecies similarity of brain injury patterns and further substantiates the reliable use of this model for the study of preterm brain injury. 1. Introduction Preterm deliveries make up more than 500,000, or approximately 12.5 percent, of all infant births in the United States [1]. Although technological advances in neonatal care have dramatically improved the survival rates for the smallest and youngest infants, such advances have yet to fully protect the developing brain from injury and prevent the neurological morbidities associated with prematurity. Of those infants born less than 32 weeks gestational age and weighing less than 1500?g (very low birth weight, VLBW), approximately 10% have motor deficits and up to 60% have neurocognitive disabilities and/or behavioral issues [2, 3]. The most common predisposing factors to premature brain injury are hypoxia-ischemia (HI) and/or sepsis [4–7]. However, all premature newborns are at risk for brain injury and a specific ischemic episode is not required [8]. Specifically, in utero HI events (placental insufficiency, chronic fetal-to-maternal hemorrhage, stroke, infection, and inflammation), perinatal events (placental abruption, respiratory failure), and neonatal disorders (chronic lung disease, congenital cardiac abnormalities) are associated with acquired brain injuries that lead to cerebral palsy, intellectual disability, epilepsy, visual and hearing impairment, and issues with school readiness [8–12].
Brain Activity in Sleep Compared to Wakefulness: A Meta-Analysis  [PDF]
Antonia J. Jakobson, Angela R. Laird, Jerome J. Maller, Russell D. Conduit, Paul B. Fitzgerald
Journal of Behavioral and Brain Science (JBBS) , 2012, DOI: 10.4236/jbbs.2012.22028
Abstract: Objective: Neuroimaging studies using a variety of techniques have been conducted in sleep to explore the changes in brain activity during the different sleep stages. The current study employed a quantitative meta-analytic technique in an attempt to integrate the findings from such studies. Methods: Using an updated version of the Activation Likelihood Estimation (ALE) method, individual meta-analyses were carried out on: 1) studies contrasting REM sleep and wakefulness, and 2) studies contrasting NREM sleep and wakefulness. Results: Based on the results of the current meta-analyses, a number of cortical and subcortical brain regions appear to be involved in sleep and sleep processes, with both decreases and increases noted across NREM and REM sleep. Specifically, areas of decreased activity comprised thalamic structures (pulvinar, dorsomedial thalamus) and frontal regions (inferior, superior, and middle frontal gyrus). Furthermore, increased and decreased activity was noted in the anterior cingulate during sleep. Conclusions: Despite limited overlap across these sleep stages among regions identified, consistent decreases were revealed in NREM sleep (thalamus) and REM sleep (frontal cortex) when compared to wakefulness. Such findings suggest that these regions may ultimately play a key role in the loss of consciousness characteristic of sleep. Further research is needed to determine if and how such activity may be related to dreaming.
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