Three Poems: The Dog at the Hospital; Bracken Ferns; Branta Canadensis

These three poems reflect the speaker\u27s refugee experience and his adjustment to the new land and the natural world and present an account of his love, companionship, and memory of war

Local Dose Effects for Late Gastrointestinal Toxicity After Hypofractionated and Conventionally Fractionated Modern Radiotherapy for Prostate Cancer in the HYPRO Trial

Purpose: Late gastrointestinal (GI) toxicity after radiotherapy for prostate cancer may have significant impact on the cancer survivor's quality of life. To da

Spatio-temporal Evolution of Diesel Sprays at the Early Start of Injection

The impact of injector life on the spatio-temporal evolution of fuel spray quality was optically investigated using high speed imaging techniques. Both new and used injectors, which had been used in intense operation for up to 90,000 miles, were considered in this investigation. Used injectors are prone to wear, deposit formation, and altered internal nozzle flow. High resolution SEM images clearly portray the presence of carbonaceous deposits both at the injector tip as well as within the holes of used injectors. Investigations revealed that used injectors tend to produce a chaotic hole-to-hole variation at the start of each injection, resulting in an asymmetric early fuel spraypenetration pattern in the first 500μs. Often those sprays thatsuffereda reduced spray tippenetration rate at the start of injection also showed off-axis transient expansions, and those sprays appeared to be bulky compared to other sprays. Following the early asymmetric spray penetration phase of injection the retarded sprays undergo rapid acceleration with time, and this transformed the early asymmetric spray pattern into a nearly uniform spray pattern from all the orifices in the quasi-steady state regime. The hole-to-hole penetration variations and the resultant asymmetric spray structure at the early start are therefore short lived transient phenomena. However if the radial expansion of the spray is large during the early phase, the radially expanded plume remains almost at the same radial location due to lack of local axial momentum, even after different time instants of spray tip propagation. This appears as a bulge to the spray and can eventually end up as a stationary local pocket of fuel vapor close to the nozzle for the entire duration of injection. This may alter the ignition, flame lift-off and entrainment characteristics of sprays injected from used or deposit rich injectors

Investigation of Spray Angle Measurement Techniques

The in-cylinder fluid-dynamic processes of fuel injection and air entrainment influence the structure and shape of evolving fuel sprays, which can subsequently alter the ignition, combustion and pollutant formation processes in diesel engines. Different spray angle detection methods have been used in the literature to investigate the global and local spray characteristics. In this work, the five most widely used diesel spray angle detection methods were identified, and used to evaluate the characteristic features of each detection method: methods with a detection range based on the spray penetration length, methods with a fixed detection range in the near and far-field spray region, triangular-based methods, and methods based on averaging local data points. The sprays were acquired from our spray chamber and processed with different thresholding techniques to explore the differences between spray angle detection methods. All five methods generated a similar global trend of spray angle variation for temporally evolving sprays over the complete injection period. However, the actual spray angle values detected by each method were not always comparable. The differences in spray angle values between the different detection methods were larger during the early start of injection, and these differences systematically decreased as the spray approached a steady-state. The methods that detected the angle in the far-field demonstrated lower spatiotemporal variability when compared to the methods that detected the angle in the near-field. An assessment ofthecomparabilitybetweenangledetectionmethodswasmadeandtheoutcomeprovidesguidanceforthe selection of the spray angle detection method.Engineering and Physical Sciences Research Council in the UK (EPSRC

Purification and Reconstitution of the Glutamate Carrier GltT of the Thermophilic Bacterium Bacillus stearothermophilus

An affinity tag consisting of six adjacent histidine residues followed by an enterokinase cleavage site was genetically engineered at the N-terminus of the glutamate transport protein GltT of the thermophilic bacterium Bacillus stearothermophilus. The fusion protein was expressed in Escherichia coli and shown to transport glutamate. The highest levels of expression were observed in E. coli strain DH5α grown on rich medium. The protein could be purified in a single step by Ni2+-NTA affinity chromatography after solubilization of the cytoplasmic membranes with the detergent Triton X100. Purified GltT was reconstituted in an active state in liposomes prepared from E. coli phospholipids. The protein was reconstituted in detergent-treated preformed liposomes, followed by removal of the detergent with polystyrene beads. Active reconstitution was realized with a wide range of Triton X100 concentrations. Neither the presence of glycerol, phospholipids, nor substrates of the transporter was necessary during the purification and reconstitution procedure to keep the enzyme in an active state. In B. stearothermophilus, GltT translocates glutamate in symport with protons or sodium ions. In membrane vesicles derived from E. coli cells expressing GltT, the Na+ ion dependency seems to be lost, suggesting a role for the lipid environment in the cation specificity. In agreement with the last observation, glutamate transport catalyzed by purified GltT reconstituted in E. coli phospholipid is driven by an electrochemical gradient of H+ but not of Na+.

Combustion of Ligaments and Droplets Expelled after the End of Injection in a Multi-hole Diesel Injector

Experimental investigations were carried out to study the end of injection spray characteristics using a number of production grade multi-hole common-rail injectors. These injectors were taken from light-duty diesel vehicles that are currently in operation on the UK roads and have done different mileages. All the production injectors suffered expulsions of ligaments and droplets after the end of injection(aeoi). It is shown that injector age/mileage has very little effect on the amount of ligaments and droplets ejected from production injectors compared to injection-to-injection variations in the amount of post-injection expulsions. Brand new production injectors also show the presence of these post-injection expulsions after every injection, which is not a desired feature of the modern solenoid actuated common-rail fuel injection system. Subsequent combustion of these post-injection ligaments and droplets lasted up to 25ms after the end of fuel injection in our high pressure, high temperature experiments, and this would contribute to engine-out soot and unburned hydrocarbon (ubhc) emissions in a firing engine.This work has been sponsored by shell Global Solutions (UK) and EPSRC

Association between incidental dose outside the prostate and tumor control after modern image-guided radiotherapy

Background and purpose: External beam radiotherapy for prostate cancer deposits incidental dose to a region surrounding the target volume. Previously, an association was identified between tumor control and incidental dose for patients treated with conventional radiotherapy. We investigated whether such an association exists for patients treated using intensity modulated radiotherapy (IMRT) and tighter margins. Materials and methods: Computed tomography scans and three-dimensional treatment planning dose distributions were available from the Dutch randomized HYPRO trial for 397 patients in the standard fractionation arm (39 × 2 Gy) and 407 patients in the hypofractionation arm (19 × 3.4 Gy), mainly delivered using online image-guided IMRT. Endpoint was any treatment failure within 5 years. A mapping of 3D dose distributions between anatomies was performed based on distance to the surface of the prostate delineation. Mean mapped dose distributions were computed for patient groups with and without failure, obtaining dose difference distributions. Random patient permutations were performed to derive p values and to identify relevant regions. Results: For high-risk patients treated in the conventional arm, higher incidental dose was significantly associated with a higher probability of tumor control in both univariate and multivariate analysis. The locations of the excess dose mainly o

The effect of on-line position correction on the dose distribution in focal radiotherapy for bladder cancer

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to determine the dosimetric effect of on-line position correction for bladder tumor irradiation and to find methods to predict and handle this effect.</p> <p>Methods</p> <p>For 25 patients with unifocal bladder cancer intensity modulated radiotherapy (IMRT) with 5 beams was planned. The requirement for each plan was that 99% of the target volume received 95% of the prescribed dose. Tumor displacements from -2.0 cm to 2.0 cm in each dimension were simulated, using 0.5 cm increments, resulting in 729 simulations per patient. We assumed that on-line correction for the tumor was applied perfectly. We determined the correlation between the change in D_99%and the change in path length, which is defined here as the distance from the skin to the isocenter for each beam. In addition the margin needed to avoid underdosage was determined and the probability that an underdosage occurs in a real treatment was calculated.</p> <p>Results</p> <p>Adjustments for tumor displacement with perfect on-line position correction resulted in an altered dose distribution. The altered fraction dose to the target varied from 91.9% to 100.4% of the prescribed dose. The mean D_99%(± SD) was 95.8% ± 1.0%. There was a modest linear correlation between the difference in D_99%and the change in path length of the beams after correction (R²= 0.590). The median probability that a systematic underdosage occurs in a real treatment was 0.23% (range: 0 - 24.5%). A margin of 2 mm reduced that probability to < 0.001% in all patients.</p> <p>Conclusion</p> <p>On-line position correction does result in an altered target coverage, due to changes in average path length after position correction. An extra margin can be added to prevent underdosage.</p