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Search Results: 1 - 10 of 371482 matches for " Glen Andrew D. De Vera "
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Anions Analysis in Ground and Tap Waters by Sequential Chemical and CO2-Suppressed Ion Chromatography
Glen Andrew D. De Vera,Ma. Pythias B. Espino
Science Diliman , 2011,
Abstract: An ion chromatographic method using conductivity detection with sequential chemical and CO2 suppression was optimized for the simultaneous determination of fluoride, chloride, bromide, nitrate,phosphate and sulfate in ground and tap water. The separation was done using an anion exchange column with an eluent of 3.2 mM Na2CO3 and 3.2 mM NaHCO3 mixture. The method was linear in the concentration range of 5 to 300 μg/L with correlation coefficients greater than 0.99 for the six inorganic anions. The method was also shown to be applicable in trace anions analysis as given by the low method detection limits (MDL). The MDL was 1μg/L for both fluoride and chloride. Bromide, nitrate, phosphate and sulfate had MDLs of 7 μg/L, 10 μg/L, 9 μg/L and 2 μg/L, respectively. Good precision was obtained as shown in the relative standard deviation of 0.1 to 12% for peak area and 0.1 to 0.3% for retention time. The sensitivity of the method improved with the addition of CO2 suppressor to chemical suppression as shown in the lower background conductivity and detection limits. The recoveries of the anions spiked in water at 300 μg/L level ranged from 100 to 104%. The method was demonstrated to be sensitive, accurate and precise for trace analysis of the six anions and was applied in the anions analysis in ground and tap waters in Malolos, Bulacan. The water samples were found to contain high concentrations of chloride of up to 476 mg/L followed by sulfate (38 mg/L), bromide (1 mg/L), phosphate (0.4 mg/L), fluoride (0.2 mg/L) and nitrate (0.1 mg/L).
Relational grounding facilitates development of scientifically useful multiscale models
C Anthony Hunt, Glen EP Ropella, Tai Lam, Andrew D Gewitz
Theoretical Biology and Medical Modelling , 2011, DOI: 10.1186/1742-4682-8-35
Abstract: A research goal (Goal 1) for computational biology, translational research, quantitative pharmacology, and other biomedical domains involves discovering and validating causal linkages between components within a biological system in both normal and pathologic settings. The translational goal (Goal 2) is to use that knowledge to improve existing and discover new therapeutic interventions. Vital to each is the formulation and implementation of computational models that, like wet-lab models, are (Goal 3) suitable objects of experimentation and represent domains in which confidence in experimental predictions is sufficient for decision making under specifiable conditions. These models, much like the systems they aim to study, must bridge multiple scales of organization, and therefore require capabilities that represent (and account for) the many uncertainties that arise in the multiscale model setting. Just as mechanistic hypotheses and insight evolve with the persistent accumulation of new wet-lab knowledge, mechanistic representations within the software constructs comprising computational models must be capable of evolving and accommodating concurrently in order to be scientifically useful. Such changes cannot be smoothly and easily achieved without prior consideration of model grounding issues at all model development stages. The purpose of this review is to provide a critical assessment of emerging technology and present arguments and examples in support of the preceding statement.A glossary is provided. When glossary terms are first used in the text, they are footnoted and defined under Endnotes. The units, dimensions, and/or objects to which a variable or model constituent refers establish groundings. Each term, variable, or object in a model has a meaning established by either an external context (foundational) or by other terms in the model (internal consistency). Absolute groundinga is most prevalent in the literature; its variables, parameters, and input-outp
Kinematic Disturbances in Optical Rotation Curves among 89 Virgo Disk Galaxies
Vera C. Rubin,Andrew H. Waterman,Jeffrey D. P. Kenney
Physics , 1999, DOI: 10.1086/300916
Abstract: For 89 galaxies, mostly spirals, in the Virgo cluster region, we have obtained optical long-slit major axis spectra of the ionized gas. We find: (1) One-half of the Virgo galaxies we observed have regular rotation patterns, while the other 50% exhibit kinematic disturbances ranging from mild to major. Velocity complexities are generally consistent with those resulting from tidal encounters or accretion events. Since kinematic disturbances are expected to fade within ~10^9 years, many Virgo galaxies have experienced several significant kinematic disturbances during their lifetimes. (2) A few Virgo galaxies have ionized gas of limited extent, with velocities exceptionally low for their luminosities. In these galaxies the gas must be not rotationally supported. (3) There is a remarkable difference in the distribution of galaxy systemic velocity for galaxies with Regular rotation curves and galaxies with Disturbed rotation curves. Galaxies with regular rotation patterns show a flat distribution with systemic velocity, while galaxies with disturbed kinematics have a Gaussian distribution very similar to that for the elliptical galaxies in Virgo. This suggests that spirals with disturbed kinematics are preferentially on radial orbits, which bring them to the cluster core, where tidal interactions are strong and/or more common. These interactions may alter the morphology of the galaxy, and may also play a role in driving the Virgo cluster toward dynamical equilibrium.
One Health approach to identify research needs in bovine and human babesioses: workshop report
Adalberto A Pérez de León, Daniel A Strickman, Donald P Knowles, Durland Fish, Eileen Thacker, José de la Fuente, Peter J Krause, Stephen K Wikel, Ryan S Miller, Gale G Wagner, Consuelo Almazán, Robert Hillman, Matthew T Messenger, Paul O Ugstad, Roberta A Duhaime, Pete D Teel, Alfonso Ortega-Santos, David G Hewitt, Edwin J Bowers, Stephen J Bent, Matt H Cochran, Terry F McElwain, Glen A Scoles, Carlos E Suarez, Ronald Davey, Jeanne M Howell Freeman, Kimberly Lohmeyer, Andrew Y Li, Felix D Guerrero, Diane M Kammlah
Parasites & Vectors , 2010, DOI: 10.1186/1756-3305-3-36
Abstract: The involvement of wildlife in the ecology of cattle fever ticks jeopardizes the ability of state and federal agencies to keep the national herd free of Texas cattle fever. Similarly, there has been a progressive increase in the number of cases of human babesiosis over the past 25 years due to an increase in the white-tailed deer population. Human babesiosis due to cattle-associated Babesia divergens and Babesia divergens-like organisms have begun to appear in residents of the United States. Research needs for human and bovine babesioses were identified and are presented herein.The translation of this research is expected to provide veterinary and public health systems with the tools to mitigate the impact of bovine and human babesioses. However, economic, political, and social commitments are urgently required, including increased national funding for animal and human Babesia research, to prevent the re-establishment of cattle fever ticks and the increasing problem of human babesiosis in the United States.Babesioses are emerging tick-borne diseases in humans and animals caused by the intraerythrocytic apicomplexan protozoa Babesia spp [1]. More than 100 species of Babesia have been described, several remain to be fully described, and it is likely that many more species remain to be discovered [2]. While ticks are second only to mosquitoes as worldwide vectors of human diseases, they are the most relevant vectors of disease-causing pathogens in domestic and wild animals [3]. Climate, host movement, animal husbandry practices, vector distribution and vector population changes affect the epidemiology of babesioses and other tick-borne diseases. Changes in these factors could result in enhanced Babesia transmission across vertebrate species by infected ticks and a greater role of certain wildlife in amplifying tick vector populations [4].The One Health concept, which is used here to define the collaborative effort of multiple disciplines to attain optimal health for pe
Over-expression of Eph and ephrin genes in advanced ovarian cancer: ephrin gene expression correlates with shortened survival
Nirmitha I Herath, Mark D Spanevello, Sabe Sabesan, Tanya Newton, Margaret Cummings, Shannon Duffy, Douglas Lincoln, Glen Boyle, Peter G Parsons, Andrew W Boyd
BMC Cancer , 2006, DOI: 10.1186/1471-2407-6-144
Abstract: Eph and ephrin expression was determined using quantitative real time RT-PCR. Correlation of gene expression was measured using Spearman's rho statistic. Survival was analysed using log-rank analysis and (was visualised by) Kaplan-Meier survival curves.Greater than 10 fold over-expression of EphA1 and a more modest over-expression of EphA2 were observed in partially overlapping subsets of tumors. Over-expression of EphA1 strongly correlated (r = 0.801; p < 0.01) with the high affinity ligand ephrin A1. A similar trend was observed between EphA2 and ephrin A1 (r = 0.387; p = 0.06). A striking correlation of both ephrin A1 and ephrin A5 expression with poor survival (r = -0.470; p = 0.02 and r = -0.562; p < 0.01) was observed. Intriguingly, there was no correlation between survival and other clinical parameters or Eph expression.These data imply that increased levels of ephrins A1 and A5 in the presence of high expression of Ephs A1 and A2 lead to a more aggressive tumor phenotype. The known functions of Eph/ephrin signalling in cell de-adhesion and movement may explain the observed correlation of ephrin expression with poor prognosis.The sixteen vertebrate Eph receptors form the largest subfamily of receptor tyrosine kinase (RTK) proteins. Activation and signalling by these receptors is mediated by interaction with nine cell-surface counter receptors known as ephrins. The ephrins are subdivided into an A group which is glycosylphosphatidyl-inositol (GPI) anchored and a B group of type I trans-membrane proteins [1]. Eph proteins are also classified into A and B groups depending on structural features and preferential binding to either A or B type ephrins [2]. Eph and ephrin proteins have important roles in facilitating de-adhesion and cell movement, thereby playing critical roles in many developmental processes [1,3,4]. Dysregulation of cell adhesion and cell motility mechanisms have emerged as key elements in tumor progression and metastasis and it is notable that a
Small area mapping of prostate cancer incidence in New York State (USA) using fully Bayesian hierarchical modelling
Glen D Johnson
International Journal of Health Geographics , 2004, DOI: 10.1186/1476-072x-3-29
Abstract: ZIP codes were chosen as mapping units for several reasons, including the need to balance between protecting personal privacy and public demand for fine geographic resolution. Since the population size varies greatly among such small mapping units, hierarchical Bayes spatial modelling was applied in this paper to produce a map of smoothed SIRs. It is further demonstrated how other characteristics of the large sample from the stationary posterior distribution of SIRs can be mapped to investigate various aspects of the statewide spatial pattern of prostate cancer incidence.Thematic mapping of the median and 95 percentile range of SIRs provided, respectively, a map of spatially smoothed values and the uncertainty associated with these smoothed values. Maps were also produced to identify ZIP codes expressing a 95% probability, in the Bayesian paradigm, of being less than or greater than the null value of 1.The model behaved as expected since areas that were statistically elevated coincided with areas identified by the spatial scan statistic, plus the relative uncertainty increased as a ZIP code's population decreased, with an exaggerated effect for low population ZIP codes on the edge of the state border.The overall smoothed pattern, along with identified high and low areas, may reflect difference across the state with respect to socio-demographics and risk factors; however, this is confounded by potential differences in screening and diagnostic follow-up. Nevertheless, the Bayes modelling approach is shown to provide not only smoothed results, but also considerable other information from a large empirical distribution of outcomes associated with each mapping unit.Geographic surveillance of chronic disease is central to understanding spatial or spatial-temporal patterns that may help to identify discrepancies in disease burden among different regions or communities. As part of ongoing efforts in New York State to understand spatial patterns of cancer and to help impleme
Looking Down the Light Cone: Can Deep Redshift Surveys Alone Measure the Power Spectrum?
Andrew A. de Laix,Glenn D. Starkman
Physics , 1998,
Abstract: We analyze the window functions for the spherical harmonic mode estimators of all--sky, volume limited surveys considering evolutionary effects along the past light--cone which include the deviation of the distance scale from a linear relationship with redshift, linear peculiar velocity corrections, and linear evolution of the density perturbations. The spherical harmonic basis functions are considered because they correspond most closely to the symmetries of typical survey geometries and of the light--cone effects we consider. Our results show substantial broadening of the windows over that expected by ignoring light--cone effects, indicating the difficulty of measuring the power spectrum independently from cosmology. We suggest that because of light--cone effects, deep redshift surveys should either be analyzed in conjunction with CMBR data which determines the cosmological parameters, or by using a Bayesian likelihood scheme in which varying cosmological parameters and a simple parameterization of the primordial power spectrum are assumed as the priors, so that observed data can be mapped from redshift to real space. The derived power spectrum can then be compared to underlying models of fluctuation generation and growth in structure formation to evaluate both these models and the cosmological priors.
Estudo avaliativo das classes de acelera??o na rede estadual paulista
Placco, Vera Maria Nigro de Souza;André, Marli E. D. Afonso de;Almeida, Laurinda Ramalho de;
Cadernos de Pesquisa , 1999, DOI: 10.1590/S0100-15741999000300003
Abstract: this article describes the proposals, methodology and results of an evaluative study on the implantation of the project for accelerated classes in the state of s?o paulo. six case studies in schools where implantation was considered to have been successful, permitted the identification of the factors for success in the project. the analysis of performance tests and of the self esteem of student graduates of the accelerated (remedial) classes indicated the importance of incorporating evaluative measures over the long and medium term to help maintain the positive results achieved.
Robustness to non-normality of common tests for the many-sample location problem
Azmeri Khan,Glen D. Rayner
Advances in Decision Sciences , 2003, DOI: 10.1155/s1173912603000178
Abstract: This paper studies the effect of deviating from the normal distribution assumption when considering the power of two many-sample location test procedures: ANOVA (parametric) and Kruskal-Wallis (non-parametric). Power functions for these tests under various conditions are produced using simulation, where the simulated data are produced using MacGillivray and Cannon's [10] recently suggested g-and-k distribution. This distribution can provide data with selected amounts of skewness and kurtosis by varying two nearly independent parameters.
A new method for measuring optical scattering properties of atmospherically relevant dusts using the Cloud and Aerosol Spectrometer with Polarization (CASPOL)
A. Glen ,S. D. Brooks
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2013,
Abstract: Atmospheric aerosols have major impacts on regional and global climate through scattering and absorption of solar radiation. A new instrument, the Cloud and Aerosol Spectrometer with Polarization (CASPOL) from Droplet Measurement Technologies measures light scattered by aerosols in the forward (4° to 12°) and backward (168° to 176°) directions, with an additional polarized detector in the backward direction. Scattering by a single particle can be measured by all three detectors for aerosols in a broad range of sizes, 0.6 μm < diameter < 50 μm. The CASPOL is a unique measurement tool, since unlike most in-situ probes, it can measure optical properties on a particle-by-particle basis. In this study, single particle CASPOL measurements for thirteen atmospherically relevant dusts were obtained and their optical scattering signatures were evaluated. In addition, Scanning Electron Microscopy (SEM) was used to characterize the shape and morphology of each type of dust. The total and polarized backscatter intensities varied with particle size for all dust types. Using a new optical signature technique all but one dust type could be categorized into one of three optical scattering groups. Additionally, a composite method was used to derive the optical signature of Arizona Test Dust (ATD) by combining the signatures of its major components. The derived signature was consistent with the measured signature of ATD. Finally, calculated backscattering cross sections for representative dust from each of the three main groups were found to vary by as much as a factor of 7, the difference between the backscattering cross sections of white quartz (5.3 × 10 10 cm 2) and hematite (4.1 × 10 9 cm 2).
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