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Search Results: 1 - 10 of 240447 matches for " Paul C. Saunders "
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Ultrasound-Guided Axillary Block in an Anticoagulated Patient after Heartmate II Implantation  [PDF]
Giuseppe Trunfio, Boris Yaguda, Paul C. Saunders, Dennis E. Feierman
Open Journal of Anesthesiology (OJAnes) , 2014, DOI: 10.4236/ojanes.2014.47022
Abstract:

Objective: This case exemplifies the understanding of the physiological changes associate with 1) Left Ventricular Assist Devices, 2) monitoring challenges associated with Left Ventricular Assist Devices and 3) the usefulness of peripheral nerve blocks in this subset of patients. Case report: A 73-year-old man was scheduled for left wrist arthroscopy and debridement to treat a very painful septic joint. He had undergone Heartmate II Left Ventricular Assist Device implantation uneventfully for Destination Therapy 4 months prior. The patient required maintenance of therapeutic anticoagulation. We elected for an ultrasound-guided axillary block, which limits the risks of vascular injury in presence of high INR. The axillary nerve block enabled us to overcome potential anesthetic problems in a patient with a continuous flow LVAD. Conclusion: The physiologic principles of Left Ventricular Assist Device function should be understood before the initiation of anesthesia. Regional Anesthesiologists can offer a very significant contribution to the safe care of patients with heart failure requiring a continuous flow Left Ventricular Assist Device.

Woodland caribou calf recruitment in relation to calving/post-calving landscape composition
Sara C. McCarthy,Robert B. Weladji,Christine Doucet,Paul Saunders
Rangifer , 2011,
Abstract: Since the 1990s, Newfoundland’s woodland caribou (Rangifer tarandus caribou) population has declined by an estimated 66%. Low calf recruitment has been associated to the decline, possibly triggered by increasing calf predation and/or decreasing resources. To investigate the role of landscape composition in this system, we studied the yearly (2005-2008) calving/post-calving range (CPCR) of 104 satellite-collared females belonging to six herds. We mapped nine disturbance factors (e.g. roads, logging, etc), as well as vegetation cover types (e.g. coniferous, deciduous forests, etc), and determined the total area they occupied within CPCRs yearly for each herd. Using an information theoretic approach, we assessed the model that best explained variation in recruitment using these components. Based on corrected Akaike Information Criterion, the model that best explained variation in calf recruitment included total disturbance and deciduous forest area, both showing the expected negative relationship with calf recruitment. Other landscape variables among the models with ΔAICc < 2 were mixed forest, also with a suggested negative relationship, and barrens and wetlands with a significant positive trend. This study highlights the need to minimize total disturbance footprint and account for resulting changes in forest composition within CPCRs during land use planning. Expanding forestry operations and road infrastructure in critical woodland caribou habitat across Canada may additionally contribute to habitat loss via fragmentation. This in turn, may lead to range recession beyond the initial local avoidance footprint. We see the possibility of using calf recruitment models based on landscape parameters, among others, to predict the impact of new industrial developments on calf recruitment.
Hammarskj ld’s visit to South Africa
C Saunders
African Journal on Conflict Resolution , 2011,
Abstract: In the last eighteen months of his life Dag Hammarskj ld was taken up with two major African issues, the Congo and South Africa. In the Congo he organised a United Nations (UN) mission to stabilise the country as it threatened to collapse into chaos following decolonisation; in South Africa he tried to deal with the conflict situation after the Sharpeville massacre by engaging in discussions with the South African Prime Minister, Hendrik Verwoerd. For that purpose he made a long-delayed visit to South Africa in January 1961. What did he try to achieve through his contacts with the South African government, and what other significance did his visit have for the unfolding history of apartheid and the struggle against it? This paper will focus on these questions, while a more substantial version, with detailed references to the sources upon which it is based, will be presented to the Dag Hammarskj ld Foundation in mid-2011 as part of the commemorations marking fifty years since Hammarskj ld’s death.
9C: A Survey of Radio Sources at 15 GHz with the Ryle Telescope
Elizabeth M. Waldram,Guy G. Pooley,Keith J. B. Grainge,Michael E. Jones,Richard D. E. Saunders,Paul F. Scott,Angela C. Taylor
Physics , 2003, DOI: 10.1046/j.1365-8711.2003.06628.x
Abstract: The fields chosen for the first observations of the cosmic microwave background with the Very Small Array have been surveyed with the Ryle Telescope at 15 GHz. We have covered three regions around RA 00h20m Dec +30deg, RA 09h40m Dec +32deg and RA 15h40m Dec +43deg (J2000), an area of 520 deg^2. There are 465 sources above the current completeness limit of approximately 25 mJy, although a total of ~760 sources have been detected, some as faint as 10 mJy. This paper describes our techniques for observation and data analysis; it also includes source counts and some discussion of spectra and variability. Preliminary source lists are presented.
Structural and ferromagnetic properties of an orthorhombic phase of MnBi stabilized with Rh additions
Valentin Taufour,Srinivasa Thimmaiah,Stephen March,Scott Saunders,Kewei Sun,Tej Nath Lamichhane,Matthew J. Kramer,Sergey L. Budko,Paul C. Canfield
Physics , 2015, DOI: 10.1103/PhysRevApplied.4.014021
Abstract: The article addresses the possibility of alloy elements in MnBi which may modify the thermodynamic stability of the NiAs-type structure without significantly degrading the magnetic properties. The addition of small amounts of Rh and Mn provides an improvement in the thermal stability with some degradation of the magnetic properties. The small amounts of Rh and Mn additions in MnBi stabilize an orthorhombic phase whose structural and magnetic properties are closely related to the ones of the previously reported high-temperature phase of MnBi (HT~MnBi). To date, the properties of the HT~MnBi, which is stable between $613$ and $719$~K, have not been studied in detail because of its transformation to the stable low-temperature MnBi (LT~MnBi), making measurements near and below its Curie temperature difficult. The Rh-stabilized MnBi with chemical formula Mn$_{1.0625-x}$Rh$_{x}$Bi [$x=0.02(1)$] adopts a new superstructure of the NiAs/Ni$_2$In structure family. It is ferromagnetic below a Curie temperature of $416$~K. The critical exponents of the ferromagnetic transition are not of the mean-field type but are closer to those associated with the Ising model in three dimensions. The magnetic anisotropy is uniaxial; the anisotropy energy is rather large, and it does not increase when raising the temperature, contrary to what happens in LT~MnBi. The saturation magnetization is approximately $3$~$\mu_B$/f.u. at low temperatures. While this exact composition may not be application ready, it does show that alloying is a viable route to modifying the stability of this class of rare-earth-free magnet alloys.
An off-axis, wide-field, diffraction-limited, reflective Schmidt Telescope
Will Saunders
Physics , 2010, DOI: 10.1117/12.856351
Abstract: Off-axis telescopes with unobstructed pupils offer great advantages in terms of emissivity, throughput, and diffractionlimited energy concentration. For most telescope designs, implementation of an off-axis configuration imposes enormous penalties in terms of cost, optical difficulty and performance, and for this reason off-axis telescopes are rarely constructed. However, for the reflective Schmidt design, implementation of an off-axis configuration is very straightforward, and involves only a modest optical penalty. Moreover, the reflective Schmidt gets particular benefits, avoiding the obstruction of its large focal plane and support column, and gaining a highly accessible, gravity-invariant prime focus, capable of accommodating very large instrumentation. We present an off-axis f/8 reflective Schmidt design for the proposed 'KDUST' Chinese infrared telescope at Dome A on the Antarctic plateau, which offers simultaneous diffraction-limited NIR imaging over 1 degree, and close to diffraction-limited imaging out to 2 degrees for fibre-fed NIR spectroscopy.
Efficient and affordable catadioptric spectrograph designs for 4MOST and Hector
Will Saunders
Physics , 2014, DOI: 10.1117/12.2055029
Abstract: Spectrograph costs have become the limiting factor in multiplexed fiber-based spectroscopic instruments, because tens of millions of resolution elements (spectral x spatial) are now required. Catadioptric (Schmidt-like) designs allow faster cameras and hence reduced detector costs, and recent advances in aspheric lens production make the overall optics costs competitive with transmissive designs. Classic Schmidt designs suffer from obstruction losses caused by the detector being within the beam. A new catadioptric design puts the detector close to the spectrograph pupil, and hence largely in the shadow of the telescope top-end obstruction. The throughput is competitive with the best transmissive designs, and much better in the Blue, where it is usually most valuable. The design also has milder aspheres and is more compact than classic Schmidts, and avoids most of their operational difficulties.
A fast new catadioptric design for fiber-fed spectrographs
Will Saunders
Physics , 2012, DOI: 10.1117/12.925704
Abstract: The next generation of massively multiplexed multi-object spectrographs (DESpec, SUMIRE, BigBOSS, 4MOST, HECTOR) demand fast, efficient and affordable spectrographs, with higher resolutions (R = 3000-5000) than current designs. Beam-size is a (relatively) free parameter in the design, but the properties of VPH gratings are such that, for fixed resolution and wavelength coverage, the effect on beam-size on overall VPH efficiency is very small. For alltransmissive cameras, this suggests modest beam-sizes (say 80-150mm) to minimize costs; while for catadioptric (Schmidt-type) cameras, much larger beam-sizes (say 250mm+) are preferred to improve image quality and to minimize obstruction losses. Schmidt designs have benefits in terms of image quality, camera speed and scattered light performance, and recent advances such as MRF technology mean that the required aspherics are no longer a prohibitive cost or risk. A new Schmidt/Maksutov-derived design is presented, which differs from previous designs in having the detector package outside the camera, and adjacent to the spectrograph pupil. The telescope pupil already contains a hole at its center, because of the obstruction from the telescope top-end. With a 250mm beam, it is possible to largely hide a 6cm \times 6cm detector package and its dewar within this hole. This means that the design achieves a very high efficiency, competitive with transmissive designs. The optics are excellent, as least as good as classic Schmidt designs, allowing F/1.25 or even faster cameras. The principal hardware has been costed at $300K per arm, making the design affordable.
Variation in the Form of Pavlovian Conditioned Approach Behavior among Outbred Male Sprague-Dawley Rats from Different Vendors and Colonies: Sign-Tracking vs. Goal-Tracking
Christopher J. Fitzpatrick, Shyam Gopalakrishnan, Elizabeth S. Cogan, Lindsay M. Yager, Paul J. Meyer, Vedran Lovic, Benjamin T. Saunders, Clarissa C. Parker, Natalia M. Gonzales, Emmanuel Aryee, Shelly B. Flagel, Abraham A. Palmer, Terry E. Robinson, Jonathan D. Morrow
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075042
Abstract: Even when trained under exactly the same conditions outbred male Sprague-Dawley (SD) rats vary in the form of the Pavlovian conditioned approach response (CR) they acquire. The form of the CR (i.e. sign-tracking vs. goal-tracking) predicts to what degree individuals attribute incentive salience to cues associated with food or drugs. However, we have noticed variation in the incidence of these two phenotypes in rats obtained from different vendors. In this study, we quantified sign- and goal-tracking behavior in a reasonably large sample of SD rats obtained from two vendors (Harlan or Charles River), as well as from individual colonies operated by both vendors. Our sample of rats acquired from Harlan had, on average, more sign-trackers than goal-trackers, and vice versa for our sample of rats acquired from Charles River. Furthermore, there were significant differences among colonies of the same vendor. Although it is impossible to rule out environmental variables, SD rats at different vendors and barriers may have reduced phenotypic heterogeneity as a result of genetic variables, such as random genetic drift or population bottlenecks. Consistent with this hypothesis, we identified marked population structure among colonies from Harlan. Therefore, despite sharing the same name, investigators should be aware that important genetic and phenotypic differences exist among SD rats from different vendors or even from different colonies of the same vendor. If used judiciously this can be an asset to experimental design, but it can also be a pitfall for those unaware of the issue.
Phenotypic spandrel: absolute discrimination and ligand antagonism
Paul Fran?ois,Kyle A. Johnson,Laura N. Saunders
Quantitative Biology , 2015,
Abstract: Recent works in quantitative evolution have shown that biological structures are constrained by selected phenotypes in unexpected ways . This is also observed in simulations of gene network evolution, where complex realistic traits naturally appear even if they have not been explicitly selected . An important biological example is the absolute discrimination between different ligand "qualities", such as immune decisions based on binding times to T cell receptors (TCRs) or Fc$\epsilon$RIs. In evolutionary simulations, the phenomenon of absolute discrimination is not achieved without detrimental ligand antagonism: a "dog in the manger" effect in which ligands unable to trigger response prevent agonists to do so. A priori it seems paradoxical to improve ligand discrimination in a context of increased ligand antagonism, and how such contradictory phenotypes can be disentangled is unclear. Here we establish for the first time a direct mathematical causal link between absolute discrimination and ligand antagonism. Inspired by the famous discussion by Gould and Lewontin, we thus qualify antagonism as a "phenotypic spandrel": a phenotype existing as a necessary by-product of another phenotype. We exhibit a general model for absolute discrimination, and further show how addition of proofreading steps inverts the expected hierarchy of antagonism without fully cancelling it. Phenotypic spandrels reveal the internal feedbacks and constraints structuring response in signalling pathways, in very similar way to symmetries structuring physical laws.
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