A concept design for an ultra-long-range survey class AUV

Gliders and flight-style Autonomous Underwater Vehicles (AUVs) are used to perform perform autonomous surveys of large areas of open ocean. Glider missions are characterized by their profiling flight pattern, slow speed, long range (1000s of km) and many month mission duration. Flight-style AUV missions are faster, of shorter range (100s of km) and multi day duration. An AUV combining many aspects of both vehicle classes would be of considerable value.This paper investigates the factors that affect the range of a traditional flight-style AUVs. A generic range model is outlined which factors in the effects of buoyancy on the range. The model shows that to create a very long range AUV it is necessary to reduce the hotel load on the AUV to the order of 1W and to add wings to overcome the vehicle’s positive buoyancy whilst travelling at the reduced speed required for long range.Using this model a concept long range AUV is outlined that is capable of travelling up to 5000km. The practical issues associated with achieving this range are also discussed

Capabilities and applications of the Program to Optimize Simulated Trajectories (POST). Program summary document

The capabilities and applications of the three-degree-of-freedom (3DOF) version and the six-degree-of-freedom (6DOF) version of the Program to Optimize Simulated Trajectories (POST) are summarized. The document supplements the detailed program manuals by providing additional information that motivates and clarifies basic capabilities, input procedures, applications and computer requirements of these programs. The information will enable prospective users to evaluate the programs, and to determine if they are applicable to their problems. Enough information is given to enable managerial personnel to evaluate the capabilities of the programs and describes the POST structure, formulation, input and output procedures, sample cases, and computer requirements. The report also provides answers to basic questions concerning planet and vehicle modeling, simulation accuracy, optimization capabilities, and general input rules. Several sample cases are presented

An Improbable Solution to the Underluminosity of 2M1207B: A Hot Protoplanet Collision Afterglow

We introduce an alternative hypothesis to explain the very low luminosity of the cool (L-type) companion to the ~25 M_Jup ~8 Myr-old brown dwarf 2M1207A. Recently, Mohanty et al. (2007) found that effective temperature estimates for 2M1207B (1600 +- 100 K) are grossly inconsistent with its lying on the same isochrone as the primary, being a factor of ~10 underluminous at all bands between I (0.8 um) and L' (3.6 um). Mohanty et al. explain this discrepency by suggesting that 2M1207B is an 8 M_Jup object surrounded by an edge-on disk comprised of large dust grains producing 2.5^m of achromatic extinction. We offer an alternative explanation: the apparent flux reflects the actual source luminosity. Given the temperature, we infer a small radius (~49,000 km), and for a range of plausible densities, we estimate a mass < M_Jup. We suggest that 2M1207B is a hot protoplanet collision afterglow and show that the radiative timescale for such an object is >~1% the age of the system. If our hypothesis is correct, the surface gravity of 2M1207B should be an order of magnitude lower than predicted by Mohanty et al. (2007).Comment: ApJ Letters, in press (11 pages

Mouse tafazzin is required for male germ cell meiosis and spermatogenesis

Barth syndrome is an X-linked mitochondrial disease, symptoms of which include neutropenia and cardiac myopathy. These symptoms are the most significant clinical consequences of a disease, which is increasingly recognised to have a variable presentation. Mutation in the Taz gene in Xq28 is thought to be responsible for the condition, by altering mitochondrial lipid content and mitochondrial function. Male chimeras carrying a targeted mutation of Taz on their X-chromosome were infertile. Testes from the Taz knockout chimeras were smaller than their control counterparts and this was associated with a disruption of the progression of spermatocytes through meiosis to spermiogenesis. Taz knockout ES cells also showed a defect when differentiated to germ cells in vitro. Mutant spermatocytes failed to progress past the pachytene stage of meiosis and had higher levels of DNA double strand damage and increased levels of endogenous retrotransposon activity. Altogether these data revealed a novel role for Taz in helping to maintain genome integrity in meiosis and facilitating germ cell differentiation. We have unravelled a novel function for the Taz protein, which should contribute to an understanding of how a disruption of the Taz gene results in the complex symptoms underlying Barth Syndrome

The dynamics and helium distribution in hydrogen-helium fluid planets

The simple case of a homogeneous planet without first-order phase transitions is considered and an investigation is conducted concerning a pure hydrogen planet in which a first-order phase transition takes place from fluid molecular hydrogen to fluid metallic hydrogen. Attention is also given to convection in the presence of a compositional gradient, the effects of helium insolubility in a cooling hydrogen-helium planet, a hydrogen-helium planet in its early evolution, and the case in which influence of phase transition occurs much later in the evolution of the planet

Project for the analysis of technology transfer Quarterly report, 1 Jul. - 30 Sep. 1969

Research activities in technology transfer progra

Emerging patterns of species richness, diversity, population density, and distribution in the skates (Rajidae) of Alaska

Six years of bottom-trawl survey data, including over 6000 trawls covering over 200 km2 of bottom area throughout Alaska’s subarctic marine waters, were analyzed for patterns in species richness, diversity, density, and distribution of skates. The Bering Sea continental shelf and slope, Aleutian Islands, and Gulf of Alaska regions were stratified by geographic subregion and depth. Species richness and relative density of skates increased with depth to the shelf break in all regions. The Bering Sea shelf was dominated by the Alaska skate (Bathyraja parmifera), but species richness and diversity were low. On the Bering Sea slope, richness and diversity were higher in the shallow stratum, and relative density appeared higher in subregions dominated by canyons. In the Aleutian Islands and Gulf of Alaska, species richness and relative density were generally highest in the deepest depth strata. The data and distribution maps presented here are based on species-level data collected throughout the marine waters of Alaska, and this article represents the most comprehensive summary of the skate fauna of the region published to date

The unrestricted Skyrme-tensor time-dependent Hartree-Fock and its application to the nuclear response from spherical to triaxial nuclei

The nuclear time-dependent Hartree-Fock model formulated in the three-dimensional space,based on the full Skyrme energy density functional and complemented with the tensor force,is presented for the first time. Full self-consistency is achieved by the model. The application to the isovector giant dipole resonance is discussed in the linear limit, ranging from spherical nuclei (16O, 120Sn) to systems displaying axial or triaxial deformation (24Mg, 28Si, 178Os, 190W, 238U). Particular attention is paid to the spin-dependent terms from the central sector of the functional, recently included together with the tensor. They turn out to be capable of producing a qualitative change on the strength distribution in this channel. The effect on the deformation properties is also discussed. The quantitative effects on the linear response are small and, overall, the giant dipole energy remains unaffected. Calculations are compared to predictions from the (quasi)-particle random phase approximation and experimental data where available, finding good agreement