44 research outputs found
Etiological Profile and Treatment Outcome of Epistaxis at a Tertiary Care Hospital in Northwestern Tanzania: A Prospective Review of 104 Cases.
Epistaxis is the commonest otolaryngological emergency affecting up to 60% of the population in their lifetime, with 6% requiring medical attention. There is paucity of published data regarding the management of epistaxis in Tanzania, especially the study area. This study was conducted to describe the etiological profile and treatment outcome of epistaxis at Bugando Medical Centre, a tertiary care hospital in Northwestern Tanzania. This was a prospective descriptive study of the cases of epistaxis managed at Bugando Medical Centre from January 2008 to December 2010. Data collected were analyzed using SPSS computer software version 15. A total of 104 patients with epistaxis were studied. Males were affected twice more than the females (2.7:1). Their mean age was 32.24 ± 12.54 years (range 4 to 82 years). The modal age group was 31-40 years. The commonest cause of epistaxis was trauma (30.8%) followed by idiopathic (26.9%) and hypertension (17.3%). Anterior nasal bleeding was noted in majority of the patients (88.7%). Non surgical measures such as observation alone (40.4%) and anterior nasal packing (38.5%) were the main intervention methods in 98.1% of cases. Surgical measures mainly intranasal tumor resection was carried out in 1.9% of cases. Arterial ligation and endovascular embolization were not performed. Complication rate was 3.8%. The overall mean of hospital stay was 7.2 ± 1.6 days (range 1 to 24 days). Five patients died giving a mortality rate of 4.8%. Trauma resulting from road traffic crush (RTC) remains the most common etiological factor for epistaxis in our setting. Most cases were successfully managed with conservative (non-surgical) treatment alone and surgical intervention with its potential complications may not be necessary in most cases and should be the last resort. Reducing the incidence of trauma from RTC will reduce the incidence of emergency epistaxis in our centre
A warm Jet in a cold ocean
Unprecedented quantities of heat are entering the Pacific sector of the Arctic Ocean through Bering Strait, particularly during summer months. Though some heat is lost to the atmosphere during autumn cooling, a significant fraction of the incoming warm, salty water subducts (dives beneath) below a cooler fresher layer of near-surface water, subsequently extending hundreds of kilometers into the Beaufort Gyre. Upward turbulent mixing of these sub-surface pockets of heat is likely accelerating sea ice melt in the region. This Pacific-origin water brings both heat and unique biogeochemical properties, contributing to a changing Arctic ecosystem. However, our ability to understand or forecast the role of this incoming water mass has been hampered by lack of understanding of the physical processes controlling subduction and evolution of this this warm water. Crucially, the processes seen here occur at small horizontal scales not resolved by regional forecast models or climate simulations; new parameterizations must be developed that accurately represent the physics. Here we present novel high resolution observations showing the detailed process of subduction and initial evolution of warm Pacific-origin water in the southern Beaufort Gyre
FED-A, an advanced performance FED based on low safety factor and current drive
This document is one of four describing studies performed in FY 1982 within the context of the Fusion Engineering Device (FED) Program for the Office of Fusion Energy, U.S. Department of Energy. The documents are: 1. FED Baseline Engineering Studies (ORNL/FEDC-82/2), 2. FED-A, An Advanced Performance FED Based on Low Safety Factor and Current Drive (this document), 3. FED-R, A Fusion Device Utilizing Resistive Magnets (ORNL/FEDC-82/1), and 4. Technology Demonstration Facility TDF. These studies extend the FED Baseline concept of FY 1981 and develop innovative and alternative concepts for the FED. The FED-A study project was carried out as part of the Innovative and Alternative Tokamak FED studies, under the direction of P. H. Rutherford, which were part of the national FED program during FY 1982. The studies were performed jointly by senior scientists in the magnetic fusion community and the staff of the Fusion Engineering Design Center (FEDC). Y-K. M. Peng of the FEDC, on assignment from Oak Ridge National Laboratory, served as the design manager
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HIGH PERFORMANCE PLASMAS ON THE NATIONAL SPHERICAL TORUS EXPERIMENT
The National Spherical Torus Experiment has produced toroidal plasmas at low aspect ratio (A = R/a = 0.86d0.68m - 1.3, where R is the major radius and a is the minor radius of the torus) with plasma currents of 1.4MA. The rapid development of the machine has led to very exciting physics results during the first full year of physics operation. Pulse lengths in excess of 0.5s have been obtained with inductive current drive. Up to 4MW of High Harmonic Fast Wave (HHFW) heating power has been applied with 6MW planned. Using only 2MW of HHFW heating power clear evidence of electron heating is sden with HHFW, as observed by the multi point Thomson scattering diagnostic. A non-inductive current drive concept known as Coaxial Helicity Injection (CHI) has driven 260kA of toroidal current. Neutral beam heating power of 5MW has been injected. Plasmas with PI ( =2p0/B2 = a measure of magnetic confinement efficiency) of 22% have been achieved, as calculated using the EFIT equilibrium reconstruction code. P limiting phenomena have been observed, and the maximum p, scales with I&z& High frequency (>MHz) magnetic fluctuations have been observed. H-mode plasmas are observed with confinement times of > 100ms. Beam heated plasmas show energy confinement times in excess of those predicted by empirical scaling expressions. Ion temperatures in excess of 2.OkeV have been measured, and power balance suggests that the power loss from the ions to the electrons may exceed the calculated classical input power to the ions
Impact of acoustic Doppler current profiler (ADCP) motion on structure function estimates of turbulent kinetic energy dissipation rate
Abstract. Turbulent mixing is a key process in the transport of heat, salt, and nutrients in the marine environment, with fluxes commonly derived directly from estimates of the turbulent kinetic energy dissipation rate, ε. Time series of ε estimates are therefore useful in helping to identify and quantify key biogeochemical processes.
The velocity structure function method can be used to determine time series of ε estimates using along-beam velocity measurements from suitably configured acoustic Doppler current profilers (ADCPs). Shear in the background current can bias such estimates; therefore, standard practice is to deduct the mean or linear trend from the along-beam velocity over the period of an observation burst. This procedure is effective if the orientation of the ADCP to the current remains constant over the burst period. However, if the orientation of the ADCP varies, a proportion of the velocity difference between bins is retained in the structure function and the resulting ε estimates will be biased. Long-term observations from a mooring with three inline ADCPs show the heading oscillating with an angular range that depends on the flow speed: from large, slow oscillations at low flow speeds to smaller, higher-frequency oscillations at higher flow speeds. The mean tilt was also determined by the flow speed, whilst the tilt oscillation range was primarily determined by surface wave height. Synthesised along-beam velocity data for an ADCP subject to sinusoidal oscillation in a sheared flow indicate that the retained proportion of the potential bias is primarily determined by the angular range of the oscillation, with the impact varying between beams depending on the mean heading relative to the flow. Since the heading is typically unconstrained in a tethered mooring, heading oscillation is likely to be the most significant influence on the retained bias for a given level of shear. Use of an instrument housing designed to reduce oscillation would mitigate the impact, whilst if the shear is linear over the observation depth range, the bias can be corrected using a modified structure function method designed to correct for bias due to surface waves.
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The Sources and Mixing Characteristics of the Agulhas Current
Recent observations taken at four principal latitudes in the Agulhas Current show that the watermass properties on either side of its dynamical core are significantly different. Inshore of its velocity core are found waters of predominantly Arabian Sea, Red Sea, and equatorial Indian Ocean origin, while offshore waters are generally from the Atlantic Ocean, the Southern Ocean, and the southeast Indian Ocean. For the most part, the inshore waters approach the Agulhas Current through the Mozambique Channel, while those offshore are circulated within the southern Indian Ocean subtropical gyre before joining the current. These disparate water masses remain distinct during their 1000-km journeys along the South African continental slope, despite the convergence, extreme velocity shears, and high eddy kinetic energies found within the Agulhas Current. Both potential vorticity conservation and kinematic arguments are discussed as potential inhibitors of along-isopycnal mixing. It is concluded that a high cross-stream gradient of potential vorticity is the dominant mechanism for watermass separation near the surface, while the kinematic steering of water particles by the current is dominant at intermediate depths, where cross-stream potential vorticity is homogeneous. Hence, three lateral mixing regimes for the Agulhas Current are suggested. The surface and thermocline waters are always inhibited from mixing, by the presence of both a strong, cross-frontal potential vorticity gradient and kinematic steering. At intermediate depths mixing is inhibited by steering alone, and thus in this regime periodic mixing is expected during meander events (such as Natal pulses), when the steering level will rise and allow cross-frontal exchange. Below the steering level in the deep waters, there is a regime of free lateral mixing. The deep waters of the Agulhas Current are homogeneous in the cross-stream sense, being from the same North Atlantic source, and their salinity steadily (and rather rapidly) decreases to the north. Here, it is suggested that mixing must be dominated by vertical processes and a large vertical mixing coefficient of order 10 cm2 s−1 is estimated
