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Search Results: 1 - 10 of 336979 matches for " H. C. Rae "
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The Safety and Feasibility of Low-Molecular-Weight He-parin Prophylaxis in Major Abdominal Surgery Combined with Neuraxial Anesthesia  [PDF]
Bogdan Protyniak, Michael C. Meadows, H. Rae Pak, Ronald S. Chamberlain
Surgical Science (SS) , 2012, DOI: 10.4236/ss.2012.34034
Abstract: Background: Global guidelines for venous thromboembolism (VTE) prophylaxis of patients undergoing major surgery are well established. However, their applicability and safety in patients receiving neuraxial anesthesia is unproven. We sought to evaluate the safety and feasibility of chemical VTE prophylaxis in a prospective group of patients undergoing major foregut procedures under a combination of epidural and general anesthesia. Methods: A prospective database of all patients undergoing major foregut surgery from 2004-2009 was maintained and analyzed. Epidural catheters were placed pre-operatively and used for post-operative analgesia for three days in all patients. Factors evaluated included age, ethnicity, sex, length of stay, duration of epidural placement, complications of epidural placement and post-operative management, and VTE events. A uniform protocol was followed regarding the timing of low-molecular-weight heparin (LMWH) administration with epidural catheter insertion/removal. Results: A total of 237 patients formed the study group. The mean age was 57 years (range, 19 - 88) among 121 (51.1%) women and 65 years (range, 20 - 95) among 116 (48.9%) men. One hundred and sixty-six patients were Caucasian (70%), 37 Black (15.6%), 15 Hispanic (6.3%), 12 Asian/Pacific (5.1%), and 7 other (3%). All epidural catheters were removed on the third post-operative day. There were a total of five VTE (2.1%) events postoperatively. No peri-operative or post-operative epidural catheter associated complications occurred. Conclusions: Concomitant epidural catheterization and LMWH anticoagulation is safe and feasible in major abdominal surgery patients, including those undergoing major hepatic resection. Guidelines for VTE prophylaxis and LMWH administration in the setting of neuraxial anesthesia are well established and applicable to this unique patient population.
On-Line Learning with Restricted Training Sets: An Exactly Solvable Case
H. C. Rae,P. Sollich,A. C. C. Coolen
Mathematics , 1998, DOI: 10.1088/0305-4470/32/18/308
Abstract: We solve the dynamics of on-line Hebbian learning in large perceptrons exactly, for the regime where the size of the training set scales linearly with the number of inputs. We consider both noiseless and noisy teachers. Our calculation cannot be extended to non-Hebbian rules, but the solution provides a convenient and welcome benchmark with which to test more general and advanced theories for solving the dynamics of learning with restricted training sets.
Non-Deterministic Learning Dynamics in Large Neural Networks due to Structural Data Bias
H. C. Rae,J. A. F. Heimel,A. C. C. Coolen
Physics , 2000, DOI: 10.1088/0305-4470/33/48/309
Abstract: We study the dynamics of on-line learning in large perceptrons, for the case of training sets with a structural bias of the input vectors, by deriving exact and closed macroscopic dynamical laws using non-equilibrium statistical mechanical tools. In sharp contrast to the more conventional theories developed for homogeneously distributed or only weakly biased data, these laws are found to describe a non-trivial and persistently non-deterministic macroscopic evolution, and a generalisation error which retains both stochastic and sample-to-sample fluctuations, even for infinitely large networks. Furthermore, for the standard error-correcting microscopic algorithms (such as the perceptron learning rule) one obtains learning curves with distinct bias-induced phases. Our theoretical predictions find excellent confirmation in numerical simulations.
TaxMan: an online facility for the coding of continuous characters for cladistic analysis
Todd C. Rae,Andy Buckley
Quantitative Biology , 2014,
Abstract: A consensus is emerging that continuous (or metric) measures can be useful in phylogenetic systematics. Many of the methods for coding such characters, how- ever, employ elements that are arbitrary and therefore should be excluded from use in cladistic analysis. The continued use of such potentially inappropriate methods can be attributed to either their simplicity or the availability of computer programs specifically designed to produce data matrices using these methods. Conversely, one of the most suitable methods, homogeneous subset coding (HSC), is underused, probably due to the lack of a suitable software implementation for this somewhat complex procedure. This paper describes TaxMan, a Web-based facility for the coding of continuous data using HSC. Data are entered using a form accessible via any internet browser and are automatically converted to a matrix suitable for input into tree-searching software. This implementation of the HSC technique provides an uncomplicated procedure for the incorporation of metric data in phylogenetic systematics. The algorithmic implementation of the HSC procedure, and interpolation of the Studentised range and maximum modulus distributions required by it, is described in detail in appendices.
Deletion of the NSm Virulence Gene of Rift Valley Fever Virus Inhibits Virus Replication in and Dissemination from the Midgut of Aedes aegypti Mosquitoes
Rebekah C. Kading ,Mary B. Crabtree,Brian H. Bird,Stuart T. Nichol,Bobbie Rae Erickson,Kalanthe Horiuchi,Brad J. Biggerstaff,Barry R. Miller
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0002670
Abstract: Background Previously, we investigated the role of the Rift Valley fever virus (RVFV) virulence genes NSs and NSm in mosquitoes and demonstrated that deletion of NSm significantly reduced the infection, dissemination, and transmission rates of RVFV in Aedes aegypti mosquitoes. The specific aim of this study was to further characterize midgut infection and escape barriers of RVFV in Ae. aegypti infected with reverse genetics-generated wild type RVFV (rRVF-wt) or RVFV lacking the NSm virulence gene (rRVF-ΔNSm) by examining sagittal sections of infected mosquitoes for viral antigen at various time points post-infection. Methodology and Principal Findings Ae. aegypti mosquitoes were fed an infectious blood meal containing either rRVF-wt or rRVF-ΔNSm. On days 0, 1, 2, 3, 4, 6, 8, 10, 12, and 14 post-infection, mosquitoes from each experimental group were fixed in 4% paraformaldehyde, paraffin-embedded, sectioned, and examined for RVFV antigen by immunofluorescence assay. Remaining mosquitoes at day 14 were assayed for infection, dissemination, and transmission. Disseminated infections were observed in mosquitoes as early as three days post infection for both virus strains. However, infection rates for rRVF-ΔNSm were statistically significantly less than for rRVF-wt. Posterior midgut infections in mosquitoes infected with rRVF-wt were extensive, whereas midgut infections of mosquitoes infected with rRVF-ΔNSm were confined to one or a few small foci. Conclusions/Significance Deletion of NSm resulted in the reduced ability of RVFV to enter, replicate, and disseminate from the midgut epithelial cells. NSm appears to have a functional role in the vector competence of mosquitoes for RVFV at the level of the midgut barrier.
Coordinated observation of field line resonance in the mid-tail
Y. Zheng, A. T. Y. Lui, I. R. Mann, K. Takahashi, J. Watermann, S.-H. Chen, I. J. Rae, T. Mukai, C. T. Russell, A. Balogh, R. F. Pfaff,H. Rème
Annales Geophysicae (ANGEO) , 2006,
Abstract: Standing Alfvén waves of 1.1 mHz (~15 min in period) were observed by the Cluster satellites in the mid-tail during 06:00-07:00 UT on 8 August 2003. Pulsations with the same frequency were also observed at several ground stations near Cluster's footpoint. The standing wave properties were determined from the electric and magnetic field measurements of Cluster. Data from the ground magnetometers indicated a latitudinal amplitude and phase structure consistent with the driven field line resonance (FLR) at 1.1 mHz. Simultaneously, quasi-periodic oscillations at different frequencies were observed in the post-midnight/early morning sector by GOES 12 (l0≈8.7), Polar (l0≈11-14) and Geotail (l0≈9.8). The 8 August 2003 event yields rare and interesting datasets. It provides, for the first time, coordinated in situ and ground-based observations of a very low frequency FLR in the mid-tail on stretched field lines.
Computed Radiography Exposure Indices in Mammography
L Koen, C Herbst, W Rae
South African Journal of Radiology , 2008,
Abstract: Background. Studies indicate that computed radiography (CR) can lead to increased radiation dose to patients. It is therefore important to relate the exposure indicators provided by CR manufacturers to the radiation dose delivered so as to assess the radiation dose delivered to patients directly from the exposure indicators. Aim. The aim of this study was to investigate the performance of an Agfa CR system in order to characterise the dose indicators provided by the system. Method. The imaging plate response was characterised in terms of entrance exposure to the plate and the digital signal indicators generated by the system (SAL – scanning average level; and lgM – logarithmic median) for different beam qualities. Several exposures were performed on a mammography unit, and the digital signal, expressed in terms of SAL and lgM for each image, was correlated with the entrance exposure on a standard American College of Radiology (ACR) phantom. From this correlation, a relationship between the Agfa dose indices (SAL and lgM) and the average glandular dose (AGD) in mammography could be established. An equation was derived to calculate the AGD delivered to the patient as a function of the exposure indicator, lgM, and the kV. Results. The results indicated that the measured AGD at 28 kV for a standard breast thickness during routine calibration with the ACR phantom was 1.58 mGy (lgM=1.99). This dose value lay within 1.5% of the value calculated using the derived equation for a standard Perspex thickness of 4.2 cm using the automatic exposure control (AEC) (1.56 mGy). The standard error in using this equation was calculated to be 8.3%. South African Journal of Radiology Vol. 12 (2) 2008: pp. 28-31
The relationship between compression force, image quality and radiation dose in mammography
A Korf, C Herbst, W Rae
South African Journal of Radiology , 2009,
Abstract: Background. Mammography aims to obtain mammograms of the best possible image quality with the least possible radiation dose. Theoretically, an increase in breast compression gives a reduction in thickness without changing the density, resulting in improved image quality and reduced radiation dose. Aim. This study investigates the relationship between compression force, phantom thickness, image quality and radiation dose. The existence of a compression point beyond which increased compression gives a change in density rather than thickness is also considered. Method. Image quality is assessed with a contrast-detail phantom within Superflab phantom on a computed radiography (CR) mammography unit using automatic exposure control (AEC). Image quality is determined by visual inspection and image quality figure (IQF) scoring. The effect of compression and lesion depth on image quality is determined. Entrance and exit doses are calculated. The relationship between entrance dose, compression and thickness is investigated, as is the existence of a compression point beyond which a change in phantom density occurs. The average glandular dose (AGD) is calculated from the scanning average level (SAL) and logarithmic mean (LgM) and compared with the allowable limit. Results. The geometry effect was not observed. An improvement in image quality with increased compression was found. Entrance dose decreased with increased compression. This trend was not observed with exit dose as AEC was used and exit dose was calculated from SAL values. The ‘change-in-density’ point of compression was determined. Both LgM and SAL could be used successfully for AGD calculation.
A pragmatic multi-centre randomised controlled trial of fluid loading in high-risk surgical patients undergoing major elective surgery - the FOCCUS study
Brian H Cuthbertson, Marion K Campbell, Stephen A Stott, Andrew Elders, Rodolfo Hernández, Dwayne Boyers, John Norrie, John Kinsella, Julie Brittenden, Jonathan Cook, Daniela Rae, Seonaidh C Cotton, David Alcorn, Jennifer Addison, Adrian Grant, the FOCCUS study group
Critical Care , 2011, DOI: 10.1186/cc10592
Abstract: This was a pragmatic, non-blinded, multi-centre, randomised, controlled trial. We sought to recruit 128 consecutive high-risk surgical patients undergoing major abdominal surgery. The patients underwent pre-operative fluid loading with 25 ml/kg of Ringer's solution in the six hours before surgery. The control group had no pre-operative fluid loading. The primary outcome was the number of hospital days after surgery with cost-effectiveness as a secondary outcome.A total of 111 patients were recruited within the study time frame in agreement with the funder. The median pre-operative fluid loading volume was 1,875 ml (IQR 1,375 to 2,025) in the fluid group compared to 0 (IQR 0 to 0) in controls with days in hospital after surgery 12.2 (SD 11.5) days compared to 17.4 (SD 20.0) and an adjusted mean difference of 5.5 days (median 2.2 days; 95% CI -0.44 to 11.44; P = 0.07). There was a reduction in adverse events in the fluid intervention group (P = 0.048) and no increase in fluid based complications. The intervention was less costly and more effective (adjusted average cost saving: £2,047; adjusted average gain in benefit: 0.0431 quality adjusted life year (QALY)) and has a high probability of being cost-effective.Pre-operative intravenous fluid loading leads to a non-significant reduction in hospital length of stay after high-risk major surgery and is likely to be cost-effective. Confirmatory work is required to determine whether these effects are reproducible, and to confirm whether this simple intervention could allow more cost-effective delivery of care.Prospective Clinical Trials, ISRCTN32188676High-risk patients undergoing major surgery are at significant risk of death or major morbidity [1,2]. One of the largest bodies of evidence in this field is around "pre-operative optimisation" in major high risk surgery [3-5]. This label characterises a highly complex intervention which comprises a raft of intervention components. These include: pre- and post-operative admiss
Procedures for listing loci and alleles of ruminants: 1991 proposals
E Andresen, T Broad, L Di Stasio, CHS Dolling, D Hill, K Huston, B Larsen, JJ Lauvergne, H Levéziel, X Malher, P Millar, AL Rae, C Renieri, EM Tucker
Genetics Selection Evolution , 1992, DOI: 10.1186/1297-9686-24-3-277
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