Is sea-basing a viable method of providing logistic support to the UK amphibious force?

Maritime power has traditionally been a central part of the UK’s defence planning and is well suited to supporting a wide range of military operations. The littoral area has always created problems for naval planners as most landings historically have had to endure a tactical separation of the naval and land components, and hence an artificial seam between the Navy and the Marines. With the end of the Cold War, amphibious operations are going to be more difficult to conduct than in the past, and amphibious forces are going to have to adopt manoeuvre warfare capabilities in order to successfully complete their missions. It is very likely that amphibious forces will have to conduct operations against a numerically superior enemy, who is on his own terrain, and be surrounded by a neutral, if not hostile populace. As such, the concept of Operational Manoeuvre From The Sea (OMFTS) whereby the sea is used as a manoeuvre space, and command and control is fast enough to cope with large amounts of information, but at the same time allow subordinates maximum flexibility to use their initiative, is increasingly attractive. It will be important not only for the combat elements to be able to use this new concept, but the Combat Service Support (CSS) elements as well

Short-Run Economic Impacts of Hurricane Katrina (and Rita)

Sturm; Erdölförderung; Offshore-Industrie; Makroökonomischer Einfluss; USA

Using pressure pulse seismology to examine basal criticality and the influence of sticky spots on glacial flow

Here we report results of water pressure pulse studies conducted at Storglaciären (Sweden) and West Washmawapta Glacier (British Columbia, Canada). Comparison of pressure pulse records with meteorological conditions at Storglaciären indicates that several periods of increased basal slip activity observed during a 10 day interval of summer 2008 were due to precipitation loading of the glacier surface, rather than to infiltration of surface water to the glacier bed; this indicates that the glacier bed was close to the failure strength for much of this interval. Pressure pulse magnitudes for the two glaciers were well-fit by power law distributions similar to those earlier observed at Trapridge Glacier (and similar in form to the Gutenberg-Richter relationship commonly used in seismology), suggesting that the mechanical processes that give rise to these distributions are robust features of soft-bedded glaciers. In contrast, interevent time distributions for both glaciers diverge from those observed at Trapridge Glacier for short recurrence intervals, suggesting that the factors that govern the rate at which these processes occur differ between glaciers. An examination of pressure pulse characteristics at West Washmawapta Glacier indicates that the establishment of a basal drainage system in summer 2008 resulted in increased stability and reduced sensitivity to meltwater input, suggesting that common assumptions about the relationship between meltwater production and ice flow are oversimplified. These results demonstrate that water pressure pulse observations can provide valuable insight into the dynamics of soft-bedded glaciers

Statistical Phylogenetic Tree Analysis Using Differences of Means

We propose a statistical method to test whether two phylogenetic trees with given alignments are significantly incongruent. Our method compares the two distributions of phylogenetic trees given by the input alignments, instead of comparing point estimations of trees. This statistical approach can be applied to gene tree analysis for example, detecting unusual events in genome evolution such as horizontal gene transfer and reshuffling. Our method uses difference of means to compare two distributions of trees, after embedding trees in a vector space. Bootstrapping alignment columns can then be applied to obtain p-values. To compute distances between means, we employ a "kernel trick" which speeds up distance calculations when trees are embedded in a high-dimensional feature space, e.g. splits or quartets feature space. In this pilot study, first we test our statistical method's ability to distinguish between sets of gene trees generated under coalescence models with species trees of varying dissimilarity. We follow our simulation results with applications to various data sets of gophers and lice, grasses and their endophytes, and different fungal genes from the same genome. A companion toolkit, {\tt Phylotree}, is provided to facilitate computational experiments.Comment: 17 pages, 6 figure

Verification and Validation of Requirements on the CEV Parachute Assembly System Using Design of Experiments

The Crew Exploration Vehicle Parachute Assembly System (CPAS) project conducts computer simulations to verify that flight performance requirements on parachute loads and terminal rate of descent are met. Design of Experiments (DoE) provides a systematic method for variation of simulation input parameters. When implemented and interpreted correctly, a DoE study of parachute simulation tools indicates values and combinations of parameters that may cause requirement limits to be violated. This paper describes one implementation of DoE that is currently being developed by CPAS, explains how DoE results can be interpreted, and presents the results of several preliminary studies. The potential uses of DoE to validate parachute simulation models and verify requirements are also explored

Finite-Size-Scaling at the Jamming Transition: Corrections to Scaling and the Correlation Length Critical Exponent

We carry out a finite size scaling analysis of the jamming transition in frictionless bi-disperse soft core disks in two dimensions. We consider two different jamming protocols: (i) quench from random initial positions, and (ii) quasistatic shearing. By considering the fraction of jammed states as a function of packing fraction for systems with different numbers of particles, we determine the spatial correlation length critical exponent $\nu\approx 1$, and show that corrections to scaling are crucial for analyzing the data. We show that earlier numerical results yielding $\nu<1$ are due to the improper neglect of these corrections.Comment: 5 pages, 4 figures -- slightly revised version as accepted for Phys. Rev. E Rapid Communication

Background-Limited Imaging in the Near-Infrared with Warm InGaAs Sensors: Applications for Time-Domain Astronomy

We describe test observations made with a customized 640 x 512 pixel Indium Gallium Arsenide (InGaAs) prototype astronomical camera on the 100" DuPont telescope. This is the first test of InGaAs as a cost-effective alternative to HgCdTe for research-grade astronomical observations. The camera exhibits an instrument background of 113 e-/sec/pixel (dark + thermal) at an operating temperature of -40C for the sensor, maintained by a simple thermo-electric cooler. The optical train and mechanical structure float at ambient temperature with no cold stop, in contrast to most IR instruments which must be cooled to mitigate thermal backgrounds. Measurements of the night sky using a reimager with plate scale of 0.4 arc seconds / pixel show that the sky flux in Y is comparable to the dark current. At J the sky brightness exceeds dark current by a factor of four, and hence dominates the noise budget. The sensor read noise of ~43e- falls below sky+dark noise for exposures of t>7 seconds in Y and 3.5 seconds in J. We present test observations of several selected science targets, including high-significance detections of a lensed Type Ia supernova, a type IIb supernova, and a z=6.3 quasar. Deeper images are obtained for two local galaxies monitored for IR transients, and a galaxy cluster at z=0.87. Finally, we observe a partial transit of the hot JupiterHATS34b, demonstrating the photometric stability required over several hours to detect a 1.2% transit depth at high significance. A tiling of available larger-format sensors would produce an IR survey instrument with significant cost savings relative to HgCdTe-based cameras, if one is willing to forego the K band. Such a camera would be sensitive for a week or more to isotropic emission from r-process kilonova ejecta similar to that observed in GW170817, over the full 190 Mpc horizon of Advanced LIGO's design sensitivity for neutron star mergers.Comment: 13 pages, 12 figures, submitted to A