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Search Results: 1 - 10 of 195153 matches for " Raymond D. Turner "
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Y-Stenting for Bifurcation Aneurysm Coil Embolization: What is the Risk?
Alejandro M. Spiotta,Jonathan Lena,M. Imran Chaudry,Raymond D. Turner,Aquilla S. Turk
Stroke Research and Treatment , 2014, DOI: 10.1155/2014/762389
Abstract: The use of two stents in a “Y” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms has been accepted as an alternative to clip reconstruction of a select subset of challenging aneurysms. We review the risks associated with Y-stenting, including its procedural complication rates, angiographic occlusion rates, rerupture, and retreatment rates. 1. Introduction Since the International Symptomatic Aneurysm Trial (ISAT) and the Barrow Ruptured Aneurysm Trial (BRAT) firmly established endovascular therapy as a valid method for treating intracranial aneurysms, development of new techniques has broadened the scope of practice to allow for the treatment of geometrically complex aneurysms. Until the introduction and widespread adoption of adjuncts to endovascular coil embolization, complex wide-necked bifurcation aneurysms had classically been treated with microsurgical clip reconstruction. Advances in endovascular techniques including balloon remodeling as well as the use of stents have allowed more of these challenging aneurysms to be treated with coil embolization. The use of two stents in a “Y” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms was first described by Chow et al. in 2004 [1]. Since that time many reports have been published demonstrating low morbidity and mortality rates associated with Y-stenting [1–14] and it has been accepted as a safe and reasonable alternative to clip reconstruction of a select subset of challenging aneurysms. But what exactly are the risks associated with Y-stenting? To address this question a thorough understanding of the technical aspects of the procedure as well as the available reported rates of complications is required. 2. Stent Assisted Coiling The technique of stent assisted coiling in the clinical setting was first described in 1997 [15] Soon after, the availability of new flexible, self-expanding intracranial stents allowed for increasing application of this technique and observation of its benefits. Stents have been quickly adopted as promising adjuncts with potential mechanical, hemodynamic, and biologic properties, imparting an advantage over coil embolization alone [15]. Stent deployment provides mechanical support to prevent coil prolapse, may serve as a conduit to divert flow, and provides a scaffold for endothelial growth and vessel healing [15–17]. In addition, an implanted stent may incur subtle changes in the parent vessel-aneurysm geometry, imparting significant hemodynamic alterations which change the inflow
Nonparametric estimation of correlation functions in longitudinal and spatial data, with application to colon carcinogenesis experiments
Yehua Li,Naisyin Wang,Meeyoung Hong,Nancy D. Turner,Joanne R. Lupton,Raymond J. Carroll
Mathematics , 2007, DOI: 10.1214/009053607000000082
Abstract: In longitudinal and spatial studies, observations often demonstrate strong correlations that are stationary in time or distance lags, and the times or locations of these data being sampled may not be homogeneous. We propose a nonparametric estimator of the correlation function in such data, using kernel methods. We develop a pointwise asymptotic normal distribution for the proposed estimator, when the number of subjects is fixed and the number of vectors or functions within each subject goes to infinity. Based on the asymptotic theory, we propose a weighted block bootstrapping method for making inferences about the correlation function, where the weights account for the inhomogeneity of the distribution of the times or locations. The method is applied to a data set from a colon carcinogenesis study, in which colonic crypts were sampled from a piece of colon segment from each of the 12 rats in the experiment and the expression level of p27, an important cell cycle protein, was then measured for each cell within the sampled crypts. A simulation study is also provided to illustrate the numerical performance of the proposed method.
Diversity and evolution of the small multidrug resistance protein family
Denice C Bay, Raymond J Turner
BMC Evolutionary Biology , 2009, DOI: 10.1186/1471-2148-9-140
Abstract: A thorough annotation of unidentified/putative SMR sequences was performed placing sequences into each of the three SMR protein subclass designations, namely small multidrug proteins (SMP), suppressor of groEL mutations (SUG), and paired small multidrug resistance (PSMR) using protein alignments and phylogenetic analysis. Examination of SMR subclass distribution within Bacteria and Archaea taxa identified specific Bacterial classes that uniquely encode for particular SMR subclass members. The extent of selective pressure acting upon each SMR subclass was determined by calculating the rate of synonymous to non-synonymous nucleotide substitutions using Syn-SCAN analysis. SUG and SMP subclasses are maintained under moderate selection pressure in comparison to integron and plasmid encoded SMR homologues. Conversely, PSMR sequences are maintained under lower levels of selection pressure, where one of the two PSMR pairs diverges in sequence more rapidly than the other. SMR genomic loci surveys identified potential SMR efflux substrates based on its gene association to putative operons that encode for genes regulating amino acid biogenesis and QAC-like metabolites. SMR subclass protein transmembrane domain alignments to Bacterial/Archaeal transporters (BAT), DMT, and MFS sequences supports SMR participation in multidrug transport evolution by identifying common TM domains.Based on this study, PSMR sequences originated recently within both SUG and SMP clades through gene duplication events and it appears that SMR members may be evolving towards specific metabolite transport.Anthropogenic drug overuse combined with the rapid horizontal distribution of multidrug efflux genes encoded on mobile genetic elements has facilitated drug resistance in distant or unrelated microorganisms [1-3]. One such gene encode small multidrug resistance (SMR) proteins which are frequently identified within the 3' conserved region of mobile genetic elements referred to as integrons [4] and on vari
Surveying Residential Burglaries: A Case Study of Local Crime Measurement
Robert Brame,Michael G. Turner,Raymond Paternoster
Statistics , 2012,
Abstract: We consider the problem of estimating the incidence of residential burglaries that occur over a well-defined period of time within the 10 most populous cities in North Carolina. Our analysis typifies some of the general issues that arise in estimating and comparing local crime rates over time and for different cities. Typically, the only information we have about crime incidence within any particular city is what that city's police department tells us, and the police can only count and describe the crimes that come to their attention. To address this, our study combines information from police-based residential burglary counts and the National Crime Victimization Survey to obtain interval estimates of residential burglary incidence at the local level. We use those estimates as a basis for commenting on the fragility of between-city and over-time comparisons that often appear in both public discourse about crime patterns.
Surface Hardness as an Indicator of Soil Strength of Agricultural Soils  [PDF]
Gaius D. Eudoxie, Dennison Phillips, Raymond Springer
Open Journal of Soil Science (OJSS) , 2012, DOI: 10.4236/ojss.2012.24040
Abstract:

Soil strength is an important quality of agricultural soils prone to traffic. Surface hardness (SH) measured by the Clegg Impact Tester (CIT) was evaluated as an indicator for assessing soil strength. Proctor tests were performed on a diverse range of soils to examine the relationships between bulk density (BD), penetration resistance (PR), SH and water content. All three indices showed typical response curves with increasing water content, with notable differences among the soils. Maximum dry bulk density (MDBD), peak penetration resistance (PPR) and peak surface hardness (PSH) showed values of 1.98 Mg m-3, 8.2 MPa and 248 Cmax for Piarco, River Estate and Piarco respectively. Corresponding critical moisture contents (CMC) were much greater for MDBD compared to PPR and PSH. SH showed a significant positive correlation with PR, but not BD. Further divulgence into the relationships between SH and other soil properties as well as crop response will facilitate greater use of the CIT.

The usefulness of 2MASS JHKs photometry for open cluster studies
Turner, D. G;
Revista mexicana de astronomía y astrofísica , 2011,
Abstract: 2mass jhks data are used to infer the reddening and distance of open clusters for which limited optical data are available. intrinsic zams color-color and color-magnitude relations are derived with reference to existing calibrations, standard stars, three uniformly-reddened clusters: stock 16, ngc 2362, and ngc 2281, and unreddened hyades dwarfs. the method of inferring interstellar reddening and distance for sparsely-populated open clusters is applied to berkeley 44, turner 1, and collinder 419, for which existing results conflict with those inferred from jhks data. the last two clusters are of special interest: turner 1 because it hosts the galaxy's longest-period classical cepheid, and collinder 419 because it lies in the cygnus x complex.
The usefulness of 2MASS JHKs photometry for open cluster studies
D. G. Turner
Revista mexicana de astronomía y astrofísica , 2011,
Abstract: Se utilizan datos en JHKs para inferir el enrojecimiento y la distancia a cúmulos abiertos para los cuales son limitados los datos disponibles en el óptico. Se obtienen relaciones color-color y color-magnitud intrínsecos de la ZAMS con referencia a calibraciones existentes, estrellas estándar, tres cúmulos enrojecidos uniformemente: Stock 16, NGC 2362, y NGC 2281, y las enanas no-enrojecidas de las Hiadas. El método para inferir el enrojecimiento interestelar y la distancia a cúmulos abiertos escasamente poblados se aplica a Berkeley 44, Turner 1, y Collinder 419, cuyos resultados existentes están en conflicto con los inferidos a partir de los datos en JHKs. Los últimos dos cúmulos son de especial interés: Turner 1 porque alberga a la Cefeida clásica con el período más largo de la Galaxia, y Collinder 419 porque yace en el complejo Cygnus X.
The derivative expansion of the exact renormalization group
Michael D. Turner
Physics , 2001,
Abstract: We formulate a method of performing non-perturbative calculations in quantum field theory, based upon a derivative expansion of the exact renormalization group. We then proceed to apply this method to the calculation of critical exponents for three dimensional O(N) symmetric theory. Finally we discuss how the approximation scheme manages to reproduce some exactly known solutions in critical phenomena.
High-throughput metal susceptibility testing of microbial biofilms
Joe J Harrison, Raymond J Turner, Howard Ceri
BMC Microbiology , 2005, DOI: 10.1186/1471-2180-5-53
Abstract: This high-throughput method generated 96-statistically equivalent biofilms in a single device and thus allowed for comparative and combinatorial experiments of media, microbial strains, exposure times and metals. By adjusting growth conditions, it was possible to examine biofilms of different microorganisms that had similar cell densities. In one example, Pseudomonas aeruginosa ATCC 27853 was up to 80 times more resistant to heavy metalloid oxyanions than Escherichia coli TG1. Further, biofilms were up to 133 times more tolerant to tellurite (TeO32-) than corresponding planktonic cultures. Regardless of the growth medium, the tolerance of biofilm and planktonic cell E. coli JM109 to metals was time-dependent.This method results in accurate, easily reproducible comparisons between the susceptibility of planktonic cells and biofilms to metals. Further, it was possible to make direct comparisons of the ability of different microbial strains to withstand metal toxicity. The data presented here also indicate that exposure time is an important variable in metal susceptibility testing of bacteria.Determination of the minimum inhibitory concentration (MIC), based on antimicrobial activity against planktonic organisms, is the standard assay for susceptibility testing. Biofilms, which present with distinct physiology compared to planktonic cells, are infamous for their ability to withstand a wide range of antimicrobials, including metals [1-4]. Despite the ubiquitous distribution of metals and the predominance of microbial biofilms in the environment and in device-associated infections, very few studies have comparatively examined biofilm susceptibility to metals relative to planktonic cells. The scarcity of data in this regard may be attributable to the existing methods used to grow biofilms, which typically include contamination prone flow systems. Metal susceptibility testing also entails challenges not encountered with antibiotics. This includes complexation of metals wit
Computational Tools for the Secondary Analysis of Metabolomics Experiments
Sean Cameron Booth,Aalim Weljie,Raymond Joseph Turner
Computational and Structural Biotechnology Journal , 2013,
Abstract: Metabolomics experiments have become commonplace in a wide variety of disciplines. By identifying and quantifying metabolites researchers can achieve a systems level understanding of metabolism. These studies produce vast swaths of data which are often only lightly interpreted due to the overwhelmingly large amount of variables that are measured. Recently, a number of computational tools have been developed which enable much deeper analysis of metabolomics data. These data have been difficult to interpret as understanding the connections between dozens of altered metabolites has often relied on the biochemical knowledge of researchers and their speculations. Modern biochemical databases provide information about the interconnectivity of metabolism which can be automatically polled using metabolomics secondary analysis tools. Starting with lists of altered metabolites, there are two main types of analysis: enrichment analysis computes which metabolic pathways have been significantly altered whereas metabolite mapping contextualizes the abundances and significances of measured metabolites into network visualizations. Many different tools have been developed for one or both of these applications. In this review the functionality and use of these software is discussed. Together these novel secondary analysis tools will enable metabolomics researchers to plumb the depths of their data and produce farther reaching biological conclusions than ever before.
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