ABSTRACT We present results of a stellar occultation by the Jupiter Trojan asteroid Patroclus and its nearly equal size moon, Menoetius. The geocentric mid-time of the event was 2013 October 21 ...06:43:02 UT. Eleven sites out of 36 successfully recorded an occultation. Seven chords across Patroclus yielded an elliptical limb fit of 124.6 by 98.2 km. There were six chords across Menoetius that yielded an elliptical limb fit of 117.2 by 93.0 km. There were three sites that got chords on both objects. At the time of the occultation we measured a separation of 664.6 km (0.247 arcsec) and a position angle for Menoetius of 265 7 measured eastward from J2000 north. Combining this occultation data with previous light curve data, the axial ratios of both objects are 1.3 : 1.21 : 1, indicative of a mostly oblate ellipsoid with a slight asymmetry in its equatorial projection. The oblate shape is not an equilibrium shape for the current rotation period, but would be if it were rotating with an ∼8 h period. This faster period is consistent with a pre-evolved state of the system with an orbital separation that is 50% smaller. Our best estimate of the system density is 0.88 g cm−3.
Predictions of aerosol deposition rates from turbulent flow using computational fluid dynamics simulations have been compared with experimental data. The influence of turbulence model choice has been ...assessed. The use of isotropic turbulence models resulted in over-prediction of
V
+
by more than 3 orders of magnitude for
τ
+
∼
0.2
, whilst the anisotropic RSM gave results in good agreement with experiment. For
τ
+
>
10
(
d
p
∼
10
μ
m
for
Re
=
9894
) there was little difference between the turbulence models. Simulations for both
Re
=
9894
and 50,000 were carried out and good performance was seen for both. The effect of drag model was assessed and resulted in little difference in predicted deposition velocity. The influence of grid resolution was also investigated and it was seen that the cell centre of the wall-adjacent cell should be at a distance of
y
+
=
2
or less for quantitative prediction of deposition. Coarser grids resulted in over-prediction for low
τ
+
.
Background The rapid expansion in use of capsule endoscopy (CE) has led to discussion about training needs and provision. The lesion recognition skills required for CE are ideally suited to ...computer-based training. Objective The aim of this study was to prospectively evaluate the educational effectiveness of a computer-based CE training and testing module on trainees with varying experience. Design This was a prospective educational evaluation study. Setting Academic endoscopy unit. Patients This study involved 28 trainees of varying CE experience (medical students, gastroenterology trainees) and 4 CE experts. Intervention Trainees (medical students and gastroenterology trainees) without CE experience completed a 60-question, computer-based test module consisting of 30-second video clips and multiple-choice questions. Without feedback, trainees then completed a comprehensive, menu-driven, computer-based CE training module. The test module was then completed a second time and feedback was given. Expert performance on the test module was benchmarked by 4 CE experts. Main Outcome Measurements The first measure was the difference in baseline performance on the test module between trainees and experts (to determine construct validity). The second measure was a change in performance on the test module after training (to determine content validity of the training module). Results A significant difference was noted in baseline performance ( P < .001) among CE experts (mean 73.8% ± 8.0%), gastroenterology trainees (49.5% ± 10.9%), and medical students (29.5% ± 3.3%). Performance improved significantly ( P < .001) in both trainee groups after training (gastroenterology trainees' posttraining score 62.1% ± 7.7%; medical students' 46.7% ± 6.8%). Conclusion Computer-based learning has a potentially significant role in the development of a training syllabus for CE and in CE accreditation.
ABSTRACT
Occultations of stars by asteroids have been observed since 1961, increasing from a very small number to now over 500 annually. We have created and regularly maintain a growing data set of ...more than 5000 observed asteroidal occultations. The data set includes the raw observations, astrometry at the 1 mas level based on centre of mass or figure (not illumination), where possible the asteroid’s diameter to 5 km or better, and fits to shape models, the separation and diameters of asteroidal satellites, and double star discoveries with typical separations being in the tens of mas or less. The data set is published at NASA’s Planetary Data System and is regularly updated. We provide here an overview of the data set, discuss the issues associated with determining the astrometry and diameters, and give examples of what can be derived from the data set. We also compare the occultation diameters of asteroids with the diameters measured by the satellites NEOWISE, AKARI AcuA, and IRAS, and show that the best satellite-determined diameter is a combination of the diameters from all three satellites.
The hemostasis laboratory has a vital role in the diagnosis and management of patients with familial and acquired haemorrhagic and thrombotic disorders. Its role in the monitoring of traditional ...anticoagulant therapy, as well as therapy using new anticoagulants, presents new challenges to the laboratory. This new edition addresses these important issues, as well as international guidelines for testing, the development of international standard materials, management of haemostasis testing from the laboratory to the point-of-care, and molecular genetic testing.
Existing high-strength low-alloy steels have been in place on landing gear for many years owing to their superior strength and cost performance. However, there have been major advances in improving ...the strength of high-performance corrosion-resisting steels. These materials have superior environmental robustness and remove the need for harmful protective coatings such as chromates and cadmium now on the list for removal under REACH legislation. A UK government-funded collaborative project is underway targeting a refined specification Custom 465
®
precipitation hardened stainless steel to replace the current material on Airbus A320 family aircraft main landing gear, a main fitting component developed by Messier-Bugatti-Dowty. This is a collaborative project between Airbus, Messier-Bugatti-Dowty, and Carpenter Technology Corporation. An extensive series of coupon tests on four production Heats of the material have been conducted, to obtain a full range of mechanical, fatigue, and corrosion properties. Custom 465
®
is an excellent replacement to the current material, with comparable tensile strength and fracture toughness, better ductility, and very good general corrosion and stress corrosion cracking resistance. Fatigue performance is the only significant area of deficit with respect to incumbent materials, fatigue initiation being often related to carbo-titanium-nitride particles and cleavage zones.
The drift-flux approach for predicting aerosol deposition within enclosed spaces has been refined and implemented within a commercial computational fluid dynamics (CFD) solver. The drift-flux model ...is tested against a previously reported study of aerosol deposition within a ventilated chamber to illustrate the performance of the approach for unsteady particle concentrations. The model has been made more general by accounting for deposition to surfaces at any angle to the gravitational vector. The algorithms for the calculation of the deposition velocity have been revised to offer improved precision. The model shows good performance when compared with the measured particle concentration decay rates. Comparison with well-mixed models shows obvious differences from the measured and drift-flux CFD approach. The dependence of point concentration measurements of decay rates on sampling time is explored and the limitations for estimating steady-state deposition behaviour are highlighted. An important aspect of aerosol ventilation of incompletely mixed enclosed spaces is illustrated. The drift-flux approach is shown to perform very well at reproducing the unsteady particle concentration decay observed.
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