Jim N. McElwaine

INTERNAL GRAVITY WAVES IN MASSIVE STARS: ANGULAR MOMENTUM TRANSPORT

We present numerical simulations of internal gravity waves (IGW) in a star with a convective core and extended radiative envelope. We report on amplitudes, spectra, dissipation, and consequent angular momentum transport by such waves. We find that these waves are generated efficiently and transport angular momentum on short timescales over large distances. We show that, as in Earths atmosphere, IGW drive equatorial flows which change magnitude and direction on short timescales. These results have profound consequences for the observational inferences of massive stars, as well as their long term angular momentum evolution. We suggest IGW angular momentum transport may explain many observational mysteries, such as: the misalignment of hot Jupiters around hot stars, the Be class of stars, Ni enrichment anomalies in massive stars, and the non-synchronous orbits of interacting binaries.

Combined analysis of eIF4E and 4E-binding protein expression predicts breast cancer survival and estimates eIF4E activity

Increased eukaryotic translation initiation factor 4E (eIF4E) expression occurs in many cancers, and makes fundamental contributions to carcinogenesis by stimulating the expression of cancer-related genes at post-transcriptional levels. This key role is highlighted by the facts that eIF4E levels can predict prognosis, and that eIF4E is an established therapeutic target. However, eIF4E activity is a complex function of expression levels and phosphorylation statuses of eIF4E and eIF4E-binding proteins (4E-BPs). Our hypothesis was that the combined analyses of these pathway components would allow insights into eIF4E activity and its influence on cancer. We have determined expression levels of eIF4E, 4E-BP1, 4E-BP2 and phosphorylated 4E-BP1 within 424 breast tumours, and have carried out analyses to combine these and relate the product to patient survival, in order to estimate eIF4E activity. We show that this analysis gives greater prognostic insights than that of eIF4E alone. We show that eIF4E and 4E-BP expression are positively associated, and that 4E-BP2 has a stronger influence on cancer behaviour than 4E-BP1. Finally, we examine eIF4E, estimated eIF4E activity, and phosphorylated 4E-BP1 as potential predictive biomarkers for eIF4E-targeted therapies, and show that each determines selection of different patient groups. We conclude that eIF4Es influence on cancer survival is modulated substantially by 4E-BPs, and that combined pathway analyses can estimate functional eIF4E.

Variation of deposition depth with slope angle in snow avalanches: Measurements from Vallée de la Sionne

[1] The snow surface height was precisely measured, with a laser scanner, before and after the passage of two dry-mixed avalanches in Vallee de la Sionne during the winter of 2005-2006. The measurements were used to calculate the depth of the deposited snow along each entire avalanche path with a height resolution of 100 mm and a horizontal resolution of 500 mm. These data are much more accurate than any previous measurements from large avalanches and show that the deposit depth is strongly negatively correlated with the slope angle. That is, on steep slopes the deposit is shallow, and on gentle slopes the deposit is deep. The time evolution of the snow depth, showing the initial erosion and final deposition as the avalanche passed, was also observed at one position using a frequency-modulated continuous wave radar. Measurements at a nearby position gave flow speed profiles and showed that the avalanche tail consists of a steady state subcritical flow that lasts for about 100 s. Eventually, the tail slowly decelerates as the depth slightly decreases, and then it comes to rest. We show that the dependency between the slope angle and the deposition depth can be explained by both a cohesive friction model and the Pouliquen h stop model.

Kulikovskiy-Sveshnikova-Beghin model of powder snow avalanches: Development and application

[1] A simple theoretical model, the Kulikovskiy–Sveshnikova–Beghin (KSB) model, is outlined, describing the motion of a particle cloud moving down an incline. This model includes both the entrainment of surrounding ambient fluid and the entrainment of particles from the slope and is equally valid for Boussinesq and non-Boussinesq flows. However, this model can predict physically impossible densities when there is significant particle entrainment. Modifications to the model are proposed which eliminate this problem by including the entrained snow volume. With the modified model, physically realistic mean densities are predicted which have a significant impact on the Richardson number–dependent ambient entrainment. The improvements are illustrated by comparing analytical solutions to the original and the modified KSB equations for the case of a particle cloud traveling on a slope of constant angle, with constant ambient fluid and particle entrainment. Solving the modified model numerically, predictions are compared

Rotational flow in gravity current heads

The structure of gravity currents and plumes, in an unbounded ambient, on a slope of arbitrary angle is analysed. Inviscid, rotational flow solutions in a wedge are used to study the flow near the front of a current, and used to show that the Froude number is and the angle of the front to the slope is 60°. This extends the result of von Kármán (1940) to arbitrary slope angles and large internal current velocities. The predictions of the theory are briefly compared with experiments and used to explain the large negative (relative to ambient) pressures involved in avalanches.

Experiments on the non‐Boussinesq flow of self‐igniting suspension currents on a steep open slope

Fiber reinforced structural components, such as panels with honeycomb cores sandwiched between at least two outer skin layers are dried to remove moisture that may have entered into the interior of the structure. For this purpose the component is cooled in a cooling environment below the freezing point to about -5 DEG to -20 DEG C. and then exposed to a reduced pressure of less than 0.5 mbar. Under these drying conditions moisture is driven out of the component by sublimation so that the moisture does not pass through the liquid phase. The drying time may be reduced by a temperature increase to 80 DEG -100 DEG C. while maintaining the low pressure. The freezing increases the capillary action for the moisture removal. However, for an increased efficiency in the moisture removal small diameter holes, e.g. 0.1 mm bores, may be drilled into the component to facilitate the moisture escape. After drying is complete the holes are closed again e.g. by laminating further cover sheets to the component. Drying time may be reduced by a temperature increase to 80 DEG -100 DEG C. while maintaining the low pressure.

FMCW radar imaging of avalanche-like snow movements

High quality field measurements of avalanche flows are required for calibrating computational models which are an essential tool in managing the threat posed by these flows. In this paper we present a new C-band FMCW radar system developed at University College London for gathering highresolution avalanche flow data. The radar employs a full deramp hardware architecture, a diverse set of frequency ramps, and an 8-channel receiver array. We also show initial results of a small-scale field trial carried out using a single channel prototype radar deployed in a snow chute. The results are presented as range-time plots. A simple calculation of the expected flow velocity due to gravity agrees with the estimated experimental value. The results demonstrate the capability of the radar system to record high range resolution microwave images of snow movements. The experiments reported here were carried out as a precursor to full trials of the radar system during which images of full scale avalanche flows will be captured.

CALCULATING INTERNAL AVALANCHE VELOCITIES FROM CORRELATION WITH ERROR ANALYSIS

Velocities inside avalanches have been calculated for many years by calculatingthe cross-correlation between opto-electronic sensors using a method pioneered by inlinecite Nishimura et al. and Dent et al. Their approachhas been widely adopted but there has been little discussion of the optimal designof such instruments and the best analysis techniques. This paper discusses some ofthe different sources of error that arise and how these can be mitigated. A statisticalframework that describes such instruments is developed and used to quantify the errors.

Evidence for explosive silicic volcanism on the Moon from the extended distribution of thorium near the Compton‐Belkovich Volcanic Complex

We reconstruct the abundance of thorium near the Compton-Belkovich Volcanic Complex on the Moon, using data from the Lunar Prospector Gamma Ray Spectrometer. We enhance the resolution via a pixon image reconstruction technique, and find that the thorium is distributed over a larger (

Washboard Road: The Dynamics of Granular Ripples Formed by Rolling Wheels

40 \mathrm{km}\times 75