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Search Results: 1 - 10 of 202464 matches for " Geoffrey P Colby "
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Treatment of mechanically-induced vasospasm of the carotid artery in a primate using intra-arterial verapamil: a technical case report
Alexander L Coon, Geoffrey P Colby, William J Mack, Lei Feng, Philip Meyers, E Sander Connolly
BMC Cardiovascular Disorders , 2004, DOI: 10.1186/1471-2261-4-11
Abstract: As part of a study assessing the placement feasibility and safety of a catheter capable of delivering intra-arterial cerebroprotective therapy, a female 16 kg baboon prophylaxed with intravenous nitroglycerin underwent transfemoral CCA catheterization with a metallic 6-Fr catheter without signs of acute spasm. The protocol dictated that the catheter remain in the CCA for 12 hours. Upon completion of the protocol, arteriography revealed a marked decrease in CCA size (mean cross-sectional area reduction = 31.6 ± 1.9%) localized along the catheter length. Intra-arterial verapamil (2 mg/2cc) was injected and arteriography was performed 10 minutes later. Image analysis at 6 points along the CCA revealed a 21.0 ± 1.7% mean increase in vessel diameter along the length of the catheter corresponding to a 46.7 ± 4.0% mean increase in cross-sectional area. Mean systemic blood pressure did not deviate more than 10 mm Hg during the procedure.Intraluminal CCBs like verapamil may constitute an effective endovascular treatment for mechanically-induced vasospasm in medium to large-sized vessels such as the CCA.Rapid advancements in endovascular technology and techniques allow for treatment of an ever-increasing range of neurovascular diseases. Despite improvements in the safety and efficacy of these procedures, complications such as vasospasm, stroke, and perforation still occur [1]. Vasospasm, or contraction of smooth muscle fibers in the wall of a vessel, is a commonly recognized adverse event that may complicate an endovascular procedure by limiting distal blood flow.Vasospasm complicates many disease states, particularly those affecting small vessels. Recently, treatment of small-vessel vasospasm has proven amenable to pharmacological intervention. For example, in the treatment of cerebral artery spasm, intravenous nitrates [2], intravenous calcium channel blockers (CCBs) [3], and intra-arterial papaverine [4] and CCBs [5] have been shown to prevent or mitigate this small artery
Femoral access in 100 consecutive subarachnoid hemorrhage patients: the "craniotomy" of endovascular neurosurgery
Alexandra R Paul, Geoffrey P Colby, Martin G Radvany, Judy Huang, Rafael J Tamargo, Alexander L Coon
BMC Research Notes , 2010, DOI: 10.1186/1756-0500-3-285
Abstract: The records of a prospective single-center aneurysm database were reviewed to identify 100 consecutive SAH patients. Using an oblique femoral arteriogram, the presence of significant atherosclerosis, iliac tortuosity, and the CFA bifurcation were assessed. The CFA bifurcation was graded according to its position with respect to the femoral head: below (grade 1), lower half (grade 2), and above the upper half (grade 3).We found a CFA bifurcation grade 1 in 50 patients (50%, mean age 51.2 years), grade 2 in 40 patients (40%, mean age 55.5 years), and grade 3 in 10 patients (10%, mean age 58.2 years). Whereas 30 of 90 patients with CFA grades I or II were male (33%), only 10% with grade 3 were male (1 of 10, p = 0.12). Mean age for significant atherosclerosis was 65.5 +/- 2.6 years versus 50.9 +/- 1.6 years (p < 0.001) without, and iliac tortuosity was 64.9 +/- 2.4 years versus 50.3 +/- 1.6 years (p < 0.001) without.Although a requisite element of endovascular treatment in SAH patients, femoral access can be complicated by a high common femoral artery bifurcation and the presence of atherosclerotic disease and/or iliac artery tortuosity. In this study, we found a grade 3 (above the femoral head) CFA bifurcation in 10% patients, with 90% of these patients being female. We also found the presence of atherosclerotic disease and iliac tortuosity to be significantly more likely in patients older than 65 years of age.Femoral access is a fundamental element of catheter-based cerebral angiography and neurointerventional procedures. The femoral artery is most commonly used for arterial access. The common femoral artery (CFA) is the continuation of the external iliac artery from the level of the inguinal ligament to its bifurcation into the profunda femoris (deep femoral artery) and the superficial femoral artery. The CFA is considered to be the safest site for arterial puncture however there is little published data relating the CFA and its bifurcation to the landmarks typicall
Oxalate Content of Miner’s Lettuce Irrigated with Water or Fertilizer Solutions  [PDF]
Madhuri Kanala, Geoffrey P. Savage
Food and Nutrition Sciences (FNS) , 2016, DOI: 10.4236/fns.2016.713118
Abstract: The total, soluble and insoluble oxalate contents of the small, large and cauline leaves and small and large stems of miner’s lettuce (Claytonia perfoliata ) plants which had been irrigated with tap water or a soluble fertilizer were extracted and measured using HPLC chromatography. Overall, all plant parts of miner’s lettuce analyzed contained high levels of total and soluble oxalates; however plants irrigated with fertilizer contained lower levels of oxalates compared with plants irrigated with water. On a dry matter basis, the small leaves contained higher levels of total oxalate when compared to the total oxalate in the large leaves. Soluble oxalate in the leaves of plants irrigated with water ranged from 2.6 to 7.5 mg/100g dry matter (DM) and was significantly higher (P < 0.05) than the leaves of the fertilizer-watered plants, which ranged from 1.8 to 2.8 mg/100g DM. The soluble oxalate in the small and large stems of the fertilizer-watered plants ranged from 1.20 to 1.5 mg/100g DM and was significantly lower (P < 0.05) than the water-treated small and large stems, which ranged from 3.75 to 4.4 mg/100g DM. It is recommended that the leaves of miner’s lettuce should be consumed in moderation.
Allen Telescope Array Multi-Frequency Observations of the Sun
Pascal Saint-Hilaire,Gordon J. Hurford,Garrett Keating,Geoffrey C. Bower,Colby Gutierrez-Kraybill
Physics , 2011, DOI: 10.1007/s11207-011-9906-3
Abstract: We present the first observations of the Sun with the Allen Telescope Array (ATA). We used up to six frequencies, from 1.43 to 6 GHz, and baselines from 6 to 300 m. To our knowledge, these are the fi?rst simultaneous multifrequency full-Sun maps obtained at microwave frequencies without mosaicing. The observations took place when the Sun was relatively quiet, although at least one active region was present each time. We present multi-frequency flux budgets for each sources on the Sun. Outside of active regions, assuming optically thin bremsstrahlung (free--free) coronal emission on top of an optically thick ~10 000 K chromosphere, the multi-frequency information can be condensed into a single, frequency-independent, "coronal bremsstrahlung contribution function" [EM/sqrt(T)] map. This technique allows the separation of the physics of emission as well as a measurement of the density structure of the corona. Deviations from this simple relationship usually indicate the presence of an additional gyroresonance-emission component, as is typical in active regions.
Pharyngeal trauma: Two unique case reports  [PDF]
Candice Colby, Charles Moore
Open Journal of Clinical Diagnostics (OJCD) , 2012, DOI: 10.4236/ojcd.2012.23013
Abstract: The neck is a complex pathway for numerous critical structures and is defined by layers of fascial planes and spaces. Traumatic interruption of these planes can occur with injury to any of the mucosal structures within the head and neck, and is often seen as a consequence of pharyngeal injury. Here, the identification and management of two interesting and unique cases of penetrating oropharyngeal trauma are discussed: oropharyngeal trauma following abuse, and a self-inflicted pharyngeal wound with subsequent foreign body ingestion. We also review the literature regarding diagnosis, treatment, and management of traumatic pharyngeal perforation, and discuss possible complications.
Fatty Acid Profile of New Zealand Grown Edible Pine Nuts (Pinus spp.)  [PDF]
Leo P. Vanhanen, Geoffrey P. Savage, Richard N. Hider
Food and Nutrition Sciences (FNS) , 2017, DOI: 10.4236/fns.2017.83020
Abstract:
Pine nuts are becoming a popular snack because of their interesting taste and positive nutritional profile. Their fatty acid profile has been reported but there is some confusion identifying named cultivars. This study presents the fatty acid profile of five different cultivars of pine nuts currently growing in the South Island of New Zealand. The data are compared to three different samples of pine nuts currently imported into NZ. Identification of the twelve different fatty acids extracted from these samples was identified by retention time using GC-FID and GC-MS methods. The peaks were further identified by comparison of the retention times with a MS Library match and their corresponding LRI value. All but two of the extracted fatty acids were identified by comparisons with a known pure fatty acid standard sample for each fatty acid. Botanical identification of the five locally grown pine nuts was confirmed by calculating the Diagnostic Index of each cultivar from its fatty acid composition.
Attendance and attainment – a comparative study
John Colby
ITALICS , 2005,
Abstract: Through data collected over a single module first year single semester at UCE the link between attendance at teaching sessions and success in assessment is positively correlated. Attendance over time during the semester is also linked to results and final success. Indicators and action points identified have been identified that give early warning of attendance problems so that early action can be taken. Possible changes in teaching methods that could be considered in the future are discussed.
Beyond Objects, Beyond Subjects: Giorgio Agamben on Animality, Particularlity and the End of Onto-theology
Colby Dickinson
Cosmos and History : the Journal of Natural and Social Philosophy , 2011,
Abstract: The work of Giorgio Agamben could perhaps best be described as an original extension of the onto-theological critique that has dominated much of the last century’s philosophical endeavors. For him, this fundamental critical perspective extends itself toward the deconstruction of traditional significations, including the boundaries said to exist between the human and the animal as well as between the human and the divine. By repeatedly unveiling these arbitrary divisions as being a result of the state of ‘original sin’ in which we dwell, Agamben aims to advance philosophical discourse ‘beyond representation’ and toward a ‘pure’ encounter with the myriad of faces always ever present before us. In this sense, he works toward redefining ‘revelation’ as being little more than an exposure of our animality, something which indeed lies now unveiled at the real root of our being. This animality is in fact locateable beyond the separation of being into form and content, a division which is rather indebted to the onto-theological representations that have governed the discourse of being.By focusing instead on the manner in which paradigms could be said to operate over and against the (sovereign) rule of representations, he articulates a movement from particularity to particularity that resists the temptation to universalize our language on being. In this sense, then, the analogical logic of the paradigm, expressed always through the absolutely singular, exposes the beings which we all are before another, rather than violently condense any given (‘whatever’) being into a formal representation. By thus determining the contours of the paradigmatic expression, this essay intends to unite several ‘loose’ strands of Agamben’s thought in order to demonstrate the consequence of this line of inquiry: that the end of representation, often criticized as a form of political nihilism, is the only way in which to develop a justifiable ethics, one beyond the traditional binary divisions of subject and object, or of universal and particular. In the end, as Agamben illustrates repeatedly, there is only the ‘thingness’ that each thing is, and which must be safeguarded in its precarity, thus paving the way (through a messianic intervention) for an ethical discourse to appear.It is a final gesture toward the messianic, then, toward a religiously-inflected terminology which hovers over his entire oeuvre, that will ultimately guide Agamben’s ‘political’ project back toward its canonical moment most clearly identifiable within the Christian heritage. As his reading of Benjamin’s relatio
On Genus Two Riemann Surfaces Formed from Sewn Tori
Geoffrey Mason,Michael P. Tuite
Mathematics , 2006, DOI: 10.1007/s00220-006-0163-5
Abstract: We describe the period matrix and other data on a higher genus Riemann surface in terms of data coming from lower genus surfaces via an explicit sewing procedure. We consider in detail the construction of a genus two Riemann surface by either sewing two punctured tori together or by sewing a twice-punctured torus to itself. In each case the genus two period matrix is explicitly described as a holomorphic map from a suitable domain (parameterized by genus one moduli and sewing parameters) to the Siegel upper half plane $\mathbb{H}_{2}$. Equivariance of these maps under certain subgroups of $Sp(4,\mathbb{Z)}$ is shown. The invertibility of both maps in a particular domain of $\mathbb{H}_{2}$ is also shown.
The Genus Two Partition Function for Free Bosonic and Lattice Vertex Operator Algebras
Geoffrey Mason,Michael P. Tuite
Mathematics , 2007,
Abstract: We define the $n$-point function for a vertex operator algebra on a genus two Riemann surface in two separate sewing schemes where either two tori are sewn together or a handle is sewn to one torus. We explicitly obtain closed formulas for the genus two partition function for the Heisenberg free bosonic string and lattice vertex operator algebras in both sewing schemes. We prove that the partition functions are holomorphic in the sewing parameters on given suitable domains and describe their modular properties. Finally, we show that the partition functions cannot be equal in the neighborhood of a two-tori degeneration point where they can be explicitly compared.
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