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Search Results: 1 - 10 of 215820 matches for " Scott L. Gardner "
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Predicting the distribution of a parasite using the ecological niche model, GARP
Haverkost, Terry R.;Gardner, Scott L.;Townsend Peterson, A.;
Revista mexicana de biodiversidad , 2010,
Abstract: the ecological niche of a parasite exists only at the nexus of certain abiotic and biotic conditions suitable for both the definitive and intermediate hosts. however, the life cycles of most parasites are not known, or are poorly known, and using known ranges of hosts to find endemic parasitic infections has been difficult. however, with ecological niche modeling, we can create potential range maps using known localities of infection. testing the validity of such maps requires knowledge of the localities of other parasites with common history. here, we find that the ecological niche of a tapeworm parasite of voles, paranoplocephala macrocephala (cestoda: anoplocephalidae), allows prediction of the presence (in ecological and geographic space) of 19 related parasite species from 3 genera in 23 different hosts throughout the nearctic. these results give credence to the idea that this group shares similar life cycle requirements despite phylogenetic distance. this work further validates ecological niche modeling as a means by which to predict occurrence of parasites when not all facets of the life cycle are confirmed. such inductive methods create the opportunity for deducing potential reservoir or intermediate hosts, and complementing studies of parasite biodiversity and community ecology.
Predicting the distribution of a parasite using the ecological niche model, GARP Predicción de la distribución de un parásito usando el modelo de nicho ecológico, GARP
Terry R. Haverkost,Scott L. Gardner,A. Townsend Peterson
Revista mexicana de biodiversidad , 2010,
Abstract: The ecological niche of a parasite exists only at the nexus of certain abiotic and biotic conditions suitable for both the definitive and intermediate hosts. However, the life cycles of most parasites are not known, or are poorly known, and using known ranges of hosts to find endemic parasitic infections has been difficult. However, with ecological niche modeling, we can create potential range maps using known localities of infection. Testing the validity of such maps requires knowledge of the localities of other parasites with common history. Here, we find that the ecological niche of a tapeworm parasite of voles, Paranoplocephala macrocephala (Cestoda: Anoplocephalidae), allows prediction of the presence (in ecological and geographic space) of 19 related parasite species from 3 genera in 23 different hosts throughout the Nearctic. These results give credence to the idea that this group shares similar life cycle requirements despite phylogenetic distance. This work further validates ecological niche modeling as a means by which to predict occurrence of parasites when not all facets of the life cycle are confirmed. Such inductive methods create the opportunity for deducing potential reservoir or intermediate hosts, and complementing studies of parasite biodiversity and community ecology. El nicho ecológico de un parásito existe sólo cuando coinciden condiciones abióticas y bióticas necesarias para los hospederos definitivos e intermediarios. No obstante, los ciclos de vida de la mayoría de los parásitos son poco conocidos; el usar áreas de distribución de hospederos para encontrar áreas endémicas de parasitismo ha resultado difícil. Con el modelado de nicho, se pueden producir mapas del área de distribución potencial con base en sitios conocidos de presencia. Para probar la validez de estos mapas, se requiere el conocimiento de sitios de presencia de otros parásitos relacionados. En este estudio, encontramos que el nicho ecológico de un gusano parásito de ratones, Paranoplocephala macrocephala (Cestoda: Anoplocephalidae) permite predecir la presencia de 19 especies relacionadas de parásitos de 3 géneros en 23 diferentes hospederos a través del Neártico. Estos resultados apoyan la idea de que este grupo comparte una historia filogenética común que se refleja en nichos compartidos y que el modelado de nichos ofrece una manera de predecir la presencia de parásitos aunque no se conozcan todos los detalles de su ciclo de vida. Estos métodos permiten deducir reservorios u hospederos para estos parásitos.
Cardiac magnetic resonance versus transthoracic echocardiography for the assessment of cardiac volumes and regional function after myocardial infarction: an intrasubject comparison using simultaneous intrasubject recordings
Blake I Gardner, Scott E Bingham, Marvin R Allen, Duane D Blatter, Jeffrey L Anderson
Cardiovascular Ultrasound , 2009, DOI: 10.1186/1476-7120-7-38
Abstract: To compare CMR with echo, 47 consecutive patients (pts 70% male; mean age = 66 ± 11 years) with MI >6 wks previously and scheduled for imaging evaluation were studied by both echo and CMR within 60 min of each other. Readers were blinded to pt information. Pearson's correlation coefficient, paired t-tests, and chi-square tests were used to compare CMR and echo measures. Further comparisons were made between pts and 30 normal controls for CMR and between pts and published normal ranges for echo.Measures of volume and function correlated moderately well between CMR and echo (r = 0.54 to 0.75, all p < 0.001), but large and systematic differences were noted in absolute measurements. Echo underestimated left ventricular (LV) volumes (by 69 ml for end-diastolic, 35 ml for end-systolic volume, both p < 0.001), stroke volume (by 34 ml, p < 0.001), and LV ejection fraction (LVEF) (by 4 percentage point, p = 0.02). CMR was much more sensitive to detection of segmental wall motion abnormalities (p < 0.001). CMR comparisons with normal controls confirmed an increase in LV volumes, a decrease in LVEF, and preservation of stroke volume after MI.This intra subject comparison after MI found large, systematic differences between CMR and echo measures of volumes, LVEF, and wall motion abnormality despite moderate inter-modality correlations, with echo underestimating each metric. CMR also provided superior detection and quantification of segmental function after MI. Serial studies of LV function in individual patients should use the same modality.Cardiac magnetic resonance (CMR) is increasingly utilized for dynamic imaging of the heart with the expectation that it will provide more accurate and reproducible measurements of cardiac chamber dimensions, volumes, and function compared to other non-invasive imaging techniques such as echocardiography and nuclear cardiography [1-3]. This expectation arises from the superior spatial resolution and more precise border definition achieved wit
Are Ascaris lumbricoides and Ascaris suum a single species?
Daniela Leles, Scott L Gardner, Karl Reinhard, Alena I?iguez, Adauto Araujo
Parasites & Vectors , 2012, DOI: 10.1186/1756-3305-5-42
Abstract: Metazoan parasites of the order Ascaridida (Phylum Nemata: Class Secernentea) are classified into several families that occur in a wide range of hosts world-wide [1]. Mammals, from marsupials to human and non-human primates, birds, reptiles, and fishes, serve as common hosts [1-3]. Iguanodont coprolites dated from 100 million years ago were found positive for ascarid eggs [4]. Although found in many different hosts, species in this group are morphologically conservative, with little variation among groups [5].Ascaris lumbricoides Linnaeus 1758 is a parasite of Homo sapiens, and Ascaris suum Goeze 1782 occurs in pigs (Sus scrofa Linnaeus 1758). These two ascarids were probably recognized by humans since prehistory, due to their abundance, adult size, symptoms, and distribution. Eggs are commonly found in coprolites, intestinal contents of mummies, and in other kind of archaeological material [6]. Because of their remarkable similarity, several hypotheses have been proposed to explain their origin in their respective hosts. 1) The first hypothesis would be: Ascaris lumbricoides (usually infecting humans) and Ascaris suum (recorded mostly from pigs) are both valid species. In this case, these two species would have originated via a speciation event from a common ancestor, probably sometime before the domestication of pigs by humans. There are no records of Ascaris from the great apes, so this hypothesis has little support. 2) Ascaris lumbricoides in humans is derived directly from the species A. suum found in pigs with A. suum then existing as a persistent ancestor. In this case the species A. lumbricoides could have arisen by an allopatric event of host-switching (pig to human). 3) Ascaris suum is derived directly from A. lumbricoides with the persistent ancestor being A. lumbricoides and A. suum being the more newly derived species. Exactly the opposite of 2 above. Finally, hypothesis 4) states that: Ascaris lumbricoides and A. suum are conspecific, this hypothesis h
A new species of Metathelazia (Nematoda: Pneumospiruridae) from the lungs of a nine-banded armadillo in Central Mexico Especie nueva de Metathelazia (Nematoda: Pneumospiruridae) de los pulmones de un armadillo del centro de México
F. Agustín Jiménez,Rogelio Rosas-Valdez,Scott L. Gardner
Revista mexicana de biodiversidad , 2013,
Abstract: Twenty-four worms were collected from the bronchioles in both lungs of a male nine-banded armadillo Dasypus novemcinctus Linnaeus, 1758 captured in Teacalco, Morelos, Mexico. The worms, herein named Metathelazia mexicana n. sp., show a constriction in the esophagus at the level of the nerve ring; males of the species have 7 pairs of papillae, fewer than the other species in the genus. Metathelazia capsulata is the most similar species to Metathelazia mexicana; however, the latter has much shorter spicules. This is the fourth species in the genus known to occur in the New World. Se recolectó un total de 24 nemátodos de las cavidades bronquiales de un armadillo de 9 bandas Dasypus novemcinctus Lineo, 1758 en la localidad de Teacalco, Morelos, México. Los nemátodos, descritos con el nombre Metathelazia mexicana, muestran una constricción en el esófago al nivel del anillo nervioso y 7 pares de papilas caudales en los machos, número que es menor al observado en las otras especies del género. Metathelazia mexicana es semejante a Metathelazia capsulata en varios rasgos morfológicos pero difiere en el tama o de las espículas, que son más cortas en la especie aquí descrita. Esta es la cuarta especie del género registrada en el continente americano.
Integration of data mining within a Strategic Knowledge Management framework
Sanaz Moayer,Scott Gardner
International Journal of Advanced Computer Sciences and Applications , 2012,
Abstract: In today’s globally interconnected economy, knowledge is recognised as a valuable intangible asset and source of competitive advantage for firms operating in both established and emerging industries. Within these contexts Knowledge Management (KM) manifests as set of organising principles and heuristics which shape management routines, structures, technologies and cultures within organisations.When employed as an integral part of business strategy KM can blend and develop the expertise and capacity embedded in human and technological networks. This may improve processes or add value to products, services, brands and reputation. We argue that if located within a suitable strategic framework, KM can enable sustainable competitive advantage by mobilising the intangible value in networks to create products, processes or services with unique characteristics that are hard to substitute or replicate. Despite the promise of integrated knowledge strategies within high technology and professional service industries, there has been limited discussion of business strategies linked to Knowledge Management in traditional capital intensive industries such as mining and petroleum. Within these industries IT-centric Knowledge Management Systems (KMS) have dominated, with varying degrees of success as business analysis, process improvement and cost reduction tools. This paper aims to explore the opportunities and benefits arising from the application of a strategic KM and Data Mining framework within the local operations of large domestic or multinational mining companies, located in Western Australia (WA). The paper presents a high level conceptual framework for integrating so called hard, ICT and soft, human systems representing the explicit and tacit knowledge embedded within broader networks of mining activity. This Strategic Knowledge Management (SKM) framework is presented as a novel first step towards improving organisational performance and realisation of the human and technological capability captured in organisational networks. The SKM framework represents a unique combination of concepts and constructs from the Strategy, Knowledge Management, Information Systems, and Data Mining literatures. It was generated from the Stage 1- Literature and industry documentation review of a two stage exploratory study. Stage 2 will comprise a quantitative case based research approach employing clearly defined metrics to describe and compare SKM activity in designated mining companies.
Genetic and dietary factors related to schizophrenia  [PDF]
Karl L. Reichelt, Michael L. G. Gardner
Open Journal of Psychiatry (OJPsych) , 2012, DOI: 10.4236/ojpsych.2012.21003
Abstract: Biochemical, immunological and epidemiological evidence increasingly support the suggestion that there is a causal relationship between gluten/gliadin and schizophrenia as originally proposed by F. C. Dohan. Furthermore the necessary physiological mechanisms exist to explain a mechanism involving bioactive peptides from these proteins, and these show that this mechanism is possible and probable in at least in a substantial subgroup of schizophrenic patients. Evidence shows a fairly strong genetic disposition, and it must be recognised that any genetic mechanism must implicate altered chemistry and function of proteins. Evidence supports the likelihood that dietary intervention is beneficial for some, and this demands further investigation. A similar conclusion may apply to autism spectrum conditions.
Numerical Simulation of Axion Quintessence
Carl L. Gardner
Advances in Mathematical Physics , 2012, DOI: 10.1155/2012/368121
Abstract: Robust, scaled cosmological equations are derived for simulating the evolution of the scalar field, the scale factor, and the Hubble parameter during both expanding and contracting phases of the universe. These scaled equations are applied to both stable (always expanding universe) and unstable axion quintessence (expanding and then collapsing universe). When applied to unstable axion quintessence, these scaled equations allow the simulations presented here to proceed much closer to the singularity at the end of a collapsing universe than any previous simulations. 1. Introduction Typically in quintessence theories with an asymptotically vanishing effective cosmological constant, the energy contrast in dark energy rises from near zero for redshifts to near one for , mimicking a true cosmological constant. At late times, the quintessence field may begin to oscillate about its minimum, behaving like nonrelativistic matter, or the quintessence field may evolve toward infinity—in both cases with vanishing vacuum energy. In such theories, there is a period between roughly 3.5?Gyr and 20?Gyr after the big bang when . However, if the universe continues to expand forever, or even if positive curvature begins to dominate at late times (after the quintessence field has evolved to its minimum) and the universe enters a contracting stage, this period when the energy densities of dark energy and matter are comparable is a small or vanishing fraction of the total lifetime of the universe. This is called the cosmic coincidence problem. However in axion quintessence (as in other unstable de Sitter quintessence models), the cosmological era with may represent a significant fraction of the universe’s lifetime if the minimum of the axion potential is negative (unstable [de Sitter] axion quintessence), thus resolving [1] the cosmic coincidence problem. (Negative or and the fate of the universe are discussed in [1] plus references therein.) The unstable axion quintessence potential , where and the Planck mass GeV, addresses the main drawbacks of quintessence models, since the facts that the minimum of the potential is at , , and but ≈?1 are interrelated aspects of the model, and they occur for an appreciable range of initial values for (the subscript “0” denotes present values). For , the initial value of the scalar field need only satisfy to produce a universe like ours [2] (due to symmetry, we can restrict our attention to ). Thus, there is a significant 23% range of the possible initial values which will produce a universe like ours. (Qualitatively similar results to
Normal Bias in the Direction of Fetal Rotation Depends on Blastomere Composition during Early Cleavage in the Mouse
Richard L. Gardner
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009610
Abstract: Interest in establishing the basis of left/right asymmetry during embryogenesis has burgeoned in recent years. Relevant studies in mammals, focused largely on the mouse, have revealed involvement of a variety of genes that are common to the process in other animals. In the mouse, lateral differences in gene expression are first evident late in gastrulation when directional rotation of nodal cilia has been implicated in effecting the normally very strong bias in handedness. Reconstructing cleavage stages with correspondingly positioned blastomeres from appropriate numbers of conceptuses with similar division planes provides a way of testing whether they differ in potency without the confounding effects of reduced cell number. In a study using this strategy, 4-cell stage conceptuses reconstructed from blastomeres produced by equatorial as opposed to meridional second cleavage were found to be compromised in their ability to support normal development. Here, in more refined reconstructions undertaken at both the 4- and 8-cell stage, no significant impairment of development to the 9th or 12th day of gestation was found for products of equatorial second cleavage or their 8-cell stage progeny. Most surprisingly, however, a significant increase in reversal of the direction of axial rotation was found specifically among fetuses developing from conceptuses reconstructed from 8-cell stage progeny of products of equatorial second cleavage. Hence, manipulations during early cleavage some 6 days before fetal asymmetries are first evident can perturb the normally very strong bias in specification of a facet of left-right asymmetry.
Braneworld Quintessential Inflation and Sum of Exponentials Potentials
Gardner, Carl L.
High Energy Physics - Phenomenology , 2007,
Abstract: Quintessential inflation--in which a single scalar field plays the role of the inflaton and quintessence--from a sum of exponentials potential V = A (exp{5 phi}+exp{sqrt{2} phi}) or V = A (exp{5 phi}+exp{phi}) or a cosh potential V = 2A cosh(5 phi) is considered in the context of five-dimensional gravitation with standard model particles confined to our 3-brane. Reheating is accomplished via gravitational particle production and the universe undergoes a transition from primordial inflation to radiation domination well before big bang nucleosynthesis. The transition to an accelerating universe due to quintessence occurs near z = 1, as in LambdaCDM. Braneworld quintessential inflation can occur for potentials with or without a minimum, and with or without eternal acceleration and an event horizon. The low z behavior of the equation of state parameter w_phi provides a clear observable signal distinguishing quintessence from a cosmological constant.
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