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Search Results: 1 - 10 of 206898 matches for " Andrew D Shaw "
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Assessment of tissue oxygen tension: comparison of dynamic fluorescence quenching and polarographic electrode technique
Andrew D Shaw, Zheng Li, Zach Thomas, Craig W Stevens
Critical Care , 2002, DOI: 10.1186/cc1457
Abstract: Both systems measured PO2 accurately in the tonometer, and there was excellent correlation between them (r2 = 0.99). The polarographic system exhibited proportional bias that was not evident with the fluorescence method. In vivo, the fluorescence quenching technique provided a readily recordable signal that varied as expected.Measurement of tissue PO2 using fluorescence quenching is at least as accurate as measurement using the Eppendorf needle electrode in vitro, and may prove useful in vivo for assessment of tissue oxygenation.Accurate measurement of PO2 in biologic tissues has been of interest to both researchers and clinicians for many years [1]. For basic scientists measurement of PO2 provides insight into the complexities of oxygen flux at the tissue level, whereas for clinicians it moves the monitoring window a step closer to the cell. PO2 monitoring has been exploited most effectively by radiation oncologists, who have used intratumoral PO2 measurements to plan and guide radiotherapy [2]. Many articles in the anesthesia and critical care literature report the application of different technologies designed to measure tissue PO2[1,3,4,5,6,7,8,9,10,11,12,13,14], but the clinical use of PO2 measurement has largely been limited to assessment of brain tissue [15,16].Existing technologies for measuring tissue PO2 are either too expensive for everyday clinical use [14] or are based on polarographic principles [17], meaning that oxygen is consumed in the measurement process. In time this oxygen consumption affects the signal itself, and this effect persists as tissue PO2 decreases, perhaps making polarographic devices less suitable for detection of tissue hypoxia. We hypothesized that a PO2 measurement technique based on dynamic fluorescence quenching would provide a way to overcome the limitations of the current polarographic technique. We report here a head-to-head bench comparison of PO2 measurement using polarography versus measurement using dynamic fluorescence
Beneficial Effects of Resistance Exercise on Glycemic Control Are Not Further Improved by Protein Ingestion
Leigh Breen, Andrew Philp, Christopher S. Shaw, Asker E. Jeukendrup, Keith Baar, Kevin D. Tipton
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0020613
Abstract: Purpose To investigate the mechanisms underpinning modifications in glucose homeostasis and insulin sensitivity 24 h after a bout of resistance exercise (RE) with or without protein ingestion. Methods Twenty-four healthy males were assigned to a control (CON; n = 8), exercise (EX; n = 8) or exercise plus protein condition (EX+PRO; n = 8). Muscle biopsy and blood samples were obtained at rest for all groups and immediately post-RE (75% 1RM, 8×10 repetitions of leg-press and extension exercise) for EX and EX+PRO only. At 24 h post-RE (or post-resting biopsy for CON), a further muscle biopsy was obtained. Participants then consumed an oral glucose load (OGTT) containing 2 g of [U-13C] glucose during an infusion of 6, 6-[2H2] glucose. Blood samples were obtained every 10 min for 2 h to determine glucose kinetics. EX+PRO ingested an additional 25 g of intact whey protein with the OGTT. A final biopsy sample was obtained at the end of the OGTT. Results Fasted plasma glucose and insulin were similar for all groups and were not different immediately post- and 24 h post-RE. Following RE, muscle glycogen was 26±8 and 19±6% lower in EX and EX+PRO, respectively. During OGTT, plasma glucose AUC was lower for EX and EX+PRO (75.1±2.7 and 75.3±2.8 mmol·L?1:120 min, respectively) compared with CON (90.6±4.1 mmol·L?1:120 min). Plasma insulin response was 13±2 and 21±4% lower for EX and CON, respectively, compared with EX+PRO. Glucose disappearance from the circulation was ~12% greater in EX and EX+PRO compared with CON. Basal 24 h post-RE and insulin-stimulated PAS-AS160/TBC1D4 phosphorylation was greater for EX and EX+PRO. Conclusions Prior RE improves glycemic control and insulin sensitivity through an increase in the rate at which glucose is disposed from the circulation. However, co-ingesting protein during a high-glucose load does not augment this response at 24 h post-exercise in healthy, insulin-sensitive individuals.
Perioperative acute kidney injury
Stacey Calvert, Andrew Shaw
Perioperative Medicine , 2012, DOI: 10.1186/2047-0525-1-6
Abstract: Acute kidney injury (AKI) occurs in 1% to 5% of all hospital admissions, and in the perioperative period has serious implications, being consistently associated with (unacceptably) high mortality, morbidity and a more complicated hospital course with associated cost implications. This is particularly the case when renal replacement therapy (RRT) is required [1-22]. It is widely recognized that AKI requiring dialysis is an independent risk factor for death [1-3]; more recently, however, even minimal increases in serum creatinine have been associated with an increase in both short and long-term mortality, regardless of whether partial or full recovery of renal function has occurred at the time of discharge [4-11]. This risk of death is independent from other postoperative complications and co-morbidities [7-9]. AKI is related to the subsequent development and progression of chronic kidney disease (CKD) and the need for future dialysis, most notably in those with a degree of pre-existing renal impairment [11-15], but also in those who have apparent recovery following an episode of AKI [7]. Despite an increase in our knowledge of AKI and advances in other relevant areas over the last two decades (including intensive care, delivery of dialysis and surgical techniques), there have been no significant changes in these outcomes [12,15-17]. As such, identification of risk factors, close monitoring of renal function and early adoption of both preventive measures and treatments remain important considerations for those taking care of perioperative patients who are likely to develop AKI.Surgery remains a leading cause of AKI in hospitalized patients (the incidence ranges from 18% to 47% depending on the definition used) [17,18]. This has been best researched in the cardiac surgery setting where it has been shown that up to 15% of patients exposed to cardiopulmonary bypass (CPB) will develop AKI, with 2% requiring RRT [23]. Depending on the criteria used to define AKI and the po
TSI Finders for Estimation of the Location of an Interference Source Using an Ariborne Array
Dan Madurasinghe,Andrew Shaw
EURASIP Journal on Advances in Signal Processing , 2008, DOI: 10.1155/2008/275716
Abstract: An algorithm based on space fast time adaptive processing to estimate the physical location of an interference source closely associated with a physical object and enhancing the detection performance against that object using a phased array radar is presented. Conventional direction finding techniques can estimate all the signals and their associated multipaths usually in a single spectrum. However, none of the techniques are currently able to identify direct path (source direction of interest) and its associated multipath individually. Without this knowledge, we are not in a position to achieve an estimation of the physical location of the interference source via ray tracing. The identification of the physical location of an interference source has become an important issue for some radar applications. The proposed technique identifies all the terrain bounced interference paths associated with the source of interest only (main lobe interferer). This is achieved via the introduction of a postprocessor known as the terrain scattered interference (TSI) finder.
Ectopic Pregnancy as a Model to Identify Endometrial Genes and Signaling Pathways Important in Decidualization and Regulated by Local Trophoblast
W. Colin Duncan, Julie L. V. Shaw, Stewart Burgess, Sarah E. McDonald, Hilary O. D. Critchley, Andrew W. Horne
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023595
Abstract: The endometrium in early pregnancy undergoes decidualization and functional changes induced by local trophoblast, which are not fully understood. We hypothesized that endometrium from tubal ectopic pregnancy (EP) could be interrogated to identify novel genes and pathways involved in these processes. Gestation-matched endometrium was collected from women with EP (n = 11) and intrauterine pregnancies (IUP) (n = 13). RNA was extracted from the tissue. In addition, tissues were prepared for histological analysis for degree of decidualization. We compared a) the samples from EP that were decidualized (n = 6) with non-decidualized samples (n = 5), and b) the decidualized EP (n = 6) with decidualization-matched IUP (n = 6) samples using an Affymetrix gene array platform, with Ingenuity Pathway Analysis, combined with quantitative RT-PCR. Expression of PRL and IGFBP1 was used to confirm the degree of decidualization in each group. There were no differences in PRL or IGFBP1 expression in the decidualization-matched samples but a marked reduction (P<0.001) in the non-decidualized samples. Decidualization was associated with increased expression of 428 genes including SCARA5 (181-fold), DKK1 (71-fold) and PROK1 (32-fold), and decreased expression of 230 genes including MMP-7 (35-fold) and SFRP4 (21-fold). The top canonical pathways associated with these differentially expressed genes were Natural Killer Cell and Wnt/b-Catenin signaling. Local trophoblast was associated with much less alteration of endometrial gene expression with an increase in 56 genes, including CSH1 (8-fold), and a reduction in 29 genes including CRISP3 (8-fold). The top associated canonical pathway was Antigen Presentation. The study of endometrium from tubal EP may promote novel insights into genes involved in decidualization and those influenced by factors from neighboring trophoblast. This has afforded unique information not highlighted by previous studies and adds to our understanding of the endometrium in early pregnancy.
An Online Randomized Controlled Trial Evaluating HIV Prevention Digital Media Interventions for Men Who Have Sex with Men
Sabina Hirshfield, Mary Ann Chiasson, Heather Joseph, Roberta Scheinmann, Wayne D. Johnson, Robert H. Remien, Francine Shuchat Shaw, Reed Emmons, Gary Yu, Andrew D. Margolis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0046252
Abstract: Background As HIV infection continues unabated, there is a need for effective interventions targeting at-risk men who have sex with men (MSM). Engaging MSM online where they meet sexual partners is critical for HIV prevention efforts. Methods A randomized controlled trial (RCT) conducted online among U.S. MSM recruited from several gay sexual networking websites assessed the impact of 2 HIV prevention videos and an HIV prevention webpage compared to a control condition for the study outcomes HIV testing, serostatus disclosure, and unprotected anal intercourse (UAI) at 60-day follow-up. Video conditions were pooled due to reduced power from low retention (53%, n = 1,631). No participant incentives were provided. Principal Findings Follow-up was completed by 1,631 (53%) of 3,092 eligible men. In the 60 days after the intervention, men in the pooled video condition were significantly more likely than men in the control to report full serostatus disclosure (‘asked and told’) with their last sexual partner (OR 1.32, 95% CI 1.01–1.74). Comparing baseline to follow-up, HIV-negative men in the pooled video (OR 0.70, 95% CI 0.54–0.91) and webpage condition (OR 0.43, 95% CI 0.25–0.72) significantly reduced UAI at follow-up. HIV-positive men in the pooled video condition significantly reduced UAI (OR 0.38, 95% CI 0.20–0.67) and serodiscordant UAI (OR 0.53, 95% CI 0.28–0.96) at follow-up. Conclusions/Significance Findings from this online RCT of MSM recruited from sexual networking websites suggest that a low cost, brief digital media intervention designed to engage critical thinking can increase HIV disclosure to sexual partners and decrease sexual risk. Effective, brief HIV prevention interventions featuring digital media that are made widely available may serve as a complementary part of an overall behavioral and biomedical strategy for reducing sexual risk by addressing the specific needs and circumstances of the target population, and by changing individual knowledge, motivations, and community norms. Trial Registration ClinicalTrials.gov NCT00649701
Mainlobe Jammer Nulling via TSI Finders: A Space Fast-Time Adaptive Processor
Madurasinghe Dan,Shaw Andrew P
EURASIP Journal on Advances in Signal Processing , 2006,
Abstract: An algorithm based on a space fast-time adaptive processor is presented for nulling the mainlobe jammer when the jammer and the target of interest share the same bearing. The computational load involved in the conventional processor, which blindly looks for the terrain-scattered interference (TSI), is required to stack a large number of consecutive range cell returns to form the space fast-time data snapshot making it almost impossible to implement in real time. This issue is resolved via the introduction of a preprocessor (a TSI finder which detects the presence of the minute levels of multipath components of the mainlobe jammer and associated time delays) which directs the STAP processor to select only two desired range returns in order to form the space fast-time data snapshot. The end result is a computationally extremely fast processor. Also a new space fast-time adaptive processor based on the super-resolution approach (eigenvector-based) is presented.
Fully Adaptive Clutter Suppression for Airborne Multichannel Phase Array Radar Using a Single A/D Converter
Dan Madurasinghe,Andrew P. Shaw
EURASIP Journal on Advances in Signal Processing , 2010, DOI: 10.1155/2010/209761
Electronic and Structural Characteristics of Zinc-Blende Wurtzite Biphasic Homostructure GaN Nanowires
Benjamin W. Jacobs,Virginia M. Ayres,Mihail P. Petkov,Joshua B. Halpern,MaoQe He,Andrew D. Baczewski,Kaylee McElroy,Martin A. Crimp,Jiaming Zhang,Harry C. Shaw
Physics , 2007, DOI: 10.1021/nl062871y
Abstract: We report a new biphasic crystalline wurtzite/zinc-blende homostructure in gallium nitride nanowires. Cathodoluminescence was used to quantitatively measure the wurtzite and zinc-blende band gaps. High resolution transmission electron microscopy was used to identify distinct wurtzite and zinc-blende crystalline phases within single nanowires through the use of selected area electron diffraction, electron dispersive spectroscopy, electron energy loss spectroscopy, and fast Fourier transform techniques. A mechanism for growth is identified.
Asymptotic solution of nonlinear moment equations for constant-rate aerosol reactors
Shaw B. D.
Mathematical Problems in Engineering , 1998,
Abstract: Nonlinear evolution equations based upon moments of the aerosol size distribution function are solved asymptotically for constant-rate aerosol reactors (i.e., where condensible monomer is added at a constant rate) operating in the free-molecular limit. The governing equations are nondimensionalized and a large parameter that controls nucleation behavior is identified. Asymptotic analyses are developed in terms of this parameter. Comparison of the asymptotic results with direct numerical integration of the governing equations is favorable. The asymptotic results provide a simplified analytical approach to estimating average particle sizes, particle number densities, and peak supersaturation values for constant-rate aerosol reactors.
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