Providing adhesion for a miniture mobile intra-abdominal device based on biomimetic principles

This paper investigates the surface adhesion characteristics required for a miniature mobile device to move around the abdominal cavity. Such a device must be capable of adhering to the tissue lining and move freely across the upper surface of the insufflated abdomen. Accordingly, the potential of utilising bioinspired solutions to facilitate wet adhesion is assessed

Generalized thermodynamics and Fokker-Planck equations. Applications to stellar dynamics, two-dimensional turbulence and Jupiter's great red spot

We introduce a new set of generalized Fokker-Planck equations that conserve energy and mass and increase a generalized entropy until a maximum entropy state is reached. The concept of generalized entropies is rigorously justified for continuous Hamiltonian systems undergoing violent relaxation. Tsallis entropies are just a special case of this generalized thermodynamics. Application of these results to stellar dynamics, vortex dynamics and Jupiter's great red spot are proposed. Our prime result is a novel relaxation equation that should offer an easily implementable parametrization of geophysical turbulence. This relaxation equation depends on a single key parameter related to the skewness of the fine-grained vorticity distribution. Usual parametrizations (including a single turbulent viscosity) correspond to the infinite temperature limit of our model. They forget a fundamental systematic drift that acts against diffusion as in Brownian theory. Our generalized Fokker-Planck equations may have applications in other fields of physics such as chemotaxis for bacterial populations. We propose the idea of a classification of generalized entropies in classes of equivalence and provide an aesthetic connexion between topics (vortices, stars, bacteries,...) which were previously disconnected.Comment: Submitted to Phys. Rev.

BRST Hamiltonian for Bulk-Quantized Gauge Theory

By treating the bulk-quantized Yang-Mills theory as a constrained system we obtain a consistent gauge-fixed BRST hamiltonian in the minimal sector. This provides an independent derivation of the 5-d lagrangian bulk action. The ground state is independent of the (anti)ghosts and is interpreted as the solution of the Fokker-Planck equation, thus establishing a direct connection to the Fokker-Planck hamiltonian. The vacuum state correlators are shown to be in agreement with correlators in lagrangian 5-d formulation. It is verified that the complete propagators remain parabolic in one-loop dimensional regularization.Comment: 23 pages, AMS-LaTeX, 1 feynmf diagram, added 2 refs email addres

Fast Zonal Field Dynamo in Collisionless Kinetic Alfven Wave Turbulence

The possibility of fast dynamo action by collisionless kinetic Alfven Wave turbulence is demonstrated. The irreversibility necessary to lock in the generated field is provided by electron Landau damping, so the induced electric field does not vanish with resistivity. Mechanisms for self-regulation of the system and the relation of these results to the theory of alpha quenching are discussed. The dynamo-generated fields have symmetry like to that of zonal flows, and thus are termed zonal fields

Dissociations within short-term memory in GluA1 AMPA receptor subunit knockout mice

GluA1 AMPA receptor subunit knockout mice display a selective impairment on short-term recognition memory tasks. In this study we tested whether GluA1 is important for short-term memory that is necessary for bridging the discontiguity between cues in trace conditioning. GluA1 knockout mice were not impaired at using short-term memory traces of T-maze floor inserts, made of different materials, to bridge the temporal gap between conditioned stimuli and reinforcement during appetitive discrimination tasks. Thus, different aspects of short-term memory are differentially sensitive to GluA1 deletion. This dissociation may reflect processing of qualitatively different short-term memory traces. Memory that results in performance of short-term recognition (e.g. for objects or places) may be different from the memory required for associative learning in trace conditioning

Energy Momentum Tensor and Marginal Deformations in Open String Field Theory

Marginal boundary deformations in a two dimensional conformal field theory correspond to a family of classical solutions of the equations of motion of open string field theory. In this paper we develop a systematic method for relating the parameter labelling the marginal boundary deformation in the conformal field theory to the parameter labelling the classical solution in open string field theory. This is done by first constructing the energy-momentum tensor associated with the classical solution in open string field theory using Noether method, and then comparing this to the answer obtained in the conformal field theory by analysing the boundary state. We also use this method to demonstrate that in open string field theory the tachyon lump solution on a circle of radius larger than one has vanishing pressure along the circle direction, as is expected for a codimension one D-brane.Comment: LaTeX file, 25 pages; v2: minor addition

Determination of spin and orbital magnetization in the ferromagnetic superconductor UCoGe

International audienceThe magnetism in the ferromagnetic superconductor UCoGe has been studied using a combination of magnetic Compton scattering, bulk magnetization, X-ray magnetic circular dichroism and electronic structure calculations, in order to determine the spin and orbital moments. The experimentally observed total spin moment, Ms, was found to be-0.24 ± 0.05 µB at 5 T. By comparison with the total moment of 0.16 ± 0.01 µB, the orbital moment, M l , was determined to be 0.40 ± 0.05 µB. The U and Co spin moments were determined to be antiparallel. We find that the U 5f electrons carry a spin moment of Us ≈-0.30 µB and that there is a Co spin moment of Cos ≈ 0.06 µB induced via hybridization. The ratio U l /Us, of −1.3 ± 0.3, shows the U moment to be itinerant. In order to ensure an accurate description of the properties of 5f systems, and to provide a critical test of the theoretical approaches, it is clearly necessary to obtain experimental data for both the spin and orbital moments, rather than just the total magnetic moment. This can be achieved simply by measuring the spin moment with magnetic Compton scattering and comparing this to the total moment from bulk magnetizatio

Identification of host odour attractants for tsetse flies. Final report 1986-1990

Tsetse flies, Glossina spp., are blood-feeding insects and vectors of trypanosomes, microorganisms which cause sleeping sickness in man and a similar disease, "nagana" in domestic animals. The economic importance of trypanosomiasis is the constraint it imposes on orderly rural development in Africa, leading to under-exploitation of infested land and over-exploitation and degradation of trypanosomiasis-free areas. Traps and targets which attract tsetse flies and kill them could provide environmentally-acceptable, appropriate technology for monitoring and control of tsetse in Africa. Unbaited devices providing only visual attraction have proved effective in monitoring and control of riverine species of tsetse, but not the savannah species found in the fly belt of Malawi, Mozambique, Zambia and Zimbabwe covered by the EDF Regional Tsetse and Trypanosomiasis Control Project (RTTCP). Previously, collaborative was begun between glossinologists of the Zimbabwe Department of Veterinary Services (DVS) and UK Tsetse Research Laboratory (TRL) and chemists at NRI. This brought together the experience of the DVS in the field, the experience of TRL in laboratory bioassay work, and the experience of NRI in using gas chromatography linked to electroantennography (GC-EAG) and chemical techniques to detect and identify insect behaviour-modifying chemicals. Tsetse attractants produced by host animals were identified and synthesised, and dispensing systems for these compounds devised. Traps and targets impregnated with insecticide, baited with these lures were shown to provide effective control of the savannah tsetse species, G. pallidipes and G. m. morsitans

Time Evolution in Superstring Field Theory on non-BPS brane.I. Rolling Tachyon and Energy-Momentum Conservation

We derive equations of motion for the tachyon field living on an unstable non-BPS D-brane in the level truncated open cubic superstring field theory in the first non-trivial approximation. We construct a special time dependent solution to this equation which describes the rolling tachyon. It starts from the perturbative vacuum and approaches one of stable vacua in infinite time. We investigate conserved energy functional and show that its different parts dominate in different stages of the evolution. We show that the pressure for this solution has its minimum at zero time and goes to minus energy at infinite time.Comment: 16 pages, 5 figures; minor correction