Swift-Hohenberg equation with broken reflection symmetry

The bistable Swift-Hohenberg equation possesses a variety of time-independent spatially localized solutions organized in the so-called snakes-and-ladders structure. This structure is a consequence of a phenomenon known as homoclinic snaking, and is in turn a consequence of spatial reversibility of the equation. We examine here the consequences of breaking spatial reversibility on the snakes-and-ladders structure. We find that the localized states now drift, and show that the snakes-and-ladders structure breaks up into a stack of isolas. We explore the evolution of this new structure with increasing reversibility breaking and study the dynamics of the system outside of the snaking region using a combination of numerical and analytical techniques

Effects of Electrical Stimulation on Wound Closure in Mice with Experimental Diabetes Mellitus

The purpose of the present study was to examine the effect of electrical stimulation (ES) on the closure of full-thickness excisional wounds in mice with type-1 experimental diabetes mellitus (DM). Alloxon monohydrate (100mg/kg) was used to induce experimental DM in mole CD-1 mice (n = 88). Full-thickness skin excisions (1cm2) in diabetic (urine glucose \u3e 0) and non-diabetic (urine glucose = 0) mice were administered 1, 3, or 5 treatments of ES (200μs, 200 Hz) for 15 minutes, at 0 (sham), 5, 10, or 12.5 volts. Alloxon injection resulted in a positive urine glucose test in 48 mice yielding an induction rate for DM of 54.5 percent. All groups exhibited decreases in wound length, perimeter, and surface area between days 2 and 16 following the creation of wounds. Non-diabetic wounds treated with ES hod the greatest percentage (60%) of closure. Diabetic wounds treated with ES hod a greater percentage of clo­sure (36%) compared with sham-treated diabetic animals (12.5%). Treatment of wounds with the highest voltage of ES (12.5V) produced significant (P \u3c 0.01) decreases in the surface area, and significant (P \u3c 0.01) changes in the shapes of wounds in both diabetic and non-diabetic animals compared with sham-treated animals. These results support the clinical use of this adjunctive therapy to accelerate the closure of ulcers due to OM

Case-Building Behavior, Persistence, and Emergence Success of \u3ci\u3ePycnopsyche Guttifer\u3c/i\u3e (Walker) (Trichoptera: Limnephilidae) in Laboratory and \u3ci\u3ein situ\u3c/i\u3e Environments: Potential Trade-Offs of Material Preference

When removed from their cases in a non-flow laboratory environment, 5th instar Pycnopsyche guttifer (Walker) larvae were always successful in constructing a new case within 24 h when woody debris was present as a material choice. Most were successful within 1 h. Larvae were never successful at case building in the absence of wood in a non-flow environment. These laboratory-constructed ‘emergency cases’ were flimsy, lacking in shape, and larger than field cases. Laboratory case size, shape, and material preference remained constant after repeated daily evacuations over a series of 10 days. Larvae could be induced to construct a case composed of mineral particles only in the absence of wood and when placed in a laboratory stream with simulated flow conditions, or in situ in a natural stream. The emergence success of P. guttifer specimens induced to build these mineral cases, however, was significantly higher than that of larvae remaining in their field cases or of larvae that built wood cases. This result is likely due to a fungal infection that affected only larvae in wood cases. Our results demonstrate a scenario where a clearly non-preferred case construction material appears to increase survival

Cloud and ice in the planetary scale circulation and in climate

The roles of the cryosphere, and of cloud-radiative interactions are investigated. The effects clouds and ice have in the climate system are examined. The cloud radiation research attempts explain the modes of interaction (feedback) between raditive transfer, cloud formation, and atmospheric dynamics. The role of sea ice in weather and climate is also discussed. Models are used to describe the ice and atmospheric dynamics under study

Why the Universe Started from a Low Entropy State

We show that the inclusion of backreaction of massive long wavelengths imposes dynamical constraints on the allowed phase space of initial conditions for inflation, which results in a superselection rule for the initial conditions. Only high energy inflation is stable against collapse due to the gravitational instability of massive perturbations. We present arguments to the effect that the initial conditions problem {\it cannot} be meaningfully addressed by thermostatistics as far as the gravitational degrees of freedom are concerned. Rather, the choice of the initial conditions for the universe in the phase space and the emergence of an arrow of time have to be treated as a dynamic selection.Comment: 12 pages, 2 figs. Final version; agrees with accepted version in Phys. Rev.

Instanton vibrations of the 3-Skyrmion

The Atiyah-Drinfeld-Hitchin-Manin matrix corresponding to a tetrahedrally symmetric 3-instanton is calculated. Some small variations of the matrix correspond to vibrations of the instanton-generated 3-Skyrmion. These vibrations are decomposed under tetrahedral symmetry and this decomposition is compared to previous knowledge of the 3-Skyrmion vibration spectrum.Comment: 10 pages, LaTeX, no figures, PRD version with longer introduction and minor change

Large time dynamics and aging of a polymer chain in a random potential

We study the out-of-equilibrium large time dynamics of a gaussian polymer chain in a quenched random potential. The dynamics studied is a simple Langevin dynamics commonly referred to as the Rouse model. The equations for the two-time correlation and response function are derived within the gaussian variational approximation. In order to implement this approximation faithfully, we employ the supersymmetric representation of the Martin-Siggia-Rose dynamical action. For a short ranged correlated random potential the equations are solved analytically in the limit of large times using certain assumptions concerning the asymptotic behavior. Two possible dynamical behaviors are identified depending upon the time separation- a stationary regime and an aging regime. In the stationary regime time translation invariance holds and so is the fluctuation dissipation theorem. The aging regime which occurs for large time separations of the two-time correlation functions is characterized by history dependence and the breakdown of certain equilibrium relations. The large time limit of the equations yields equations among the order parameters that are similar to the equations obtained in the statics using replicas. In particular the aging solution corresponds to the broken replica solution. But there is a difference in one equation that leads to important consequences for the solution. The stationary regime corresponds to the motion of the polymer inside a local minimum of the random potential, whereas in the aging regime the polymer hops between different minima. As a byproduct we also solve exactly the dynamics of a chain in a random potential with quadratic correlations.Comment: 21 pages, RevTeX

The 1996 research assessment exercise : the library and information management panel

Reports on the 1996 Research Assessment Exercise (RAE), the fourth such exercise aimed at providing funding councils of UK universities (including former polytechnics) with the necessary data to rate the quality of UK academic research for predetermined units of assessment in order to fund research selectively. Previous RAEs were conducted in 1986, 1989, and 1992 (for a report of the 1992 RAE see JOLIS 26 (3) Sep 94, 141-7 (LISA ref. 9409765)). Reports generally on the work of the Library and Information Management Panel in agreeing criteria specific to their assessment task, particularly the five principal modes of publication: research monographs; articles in scholarly periodicals; refereed conference papers; published research reports; and book chapters. Discusses the methodology used by the Panel, research submissions received and the overall results

Symmetric Skyrmions

We present candidates for the global minimum energy solitons of charge one to nine in the Skyrme model, generated using sophisticated numerical algorithms. Assuming the Skyrme model accurately represents the low energy limit of QCD, these configurations correspond to the classical nuclear ground states of the light elements. The solitons found are particularly symmetric, for example, the charge seven skyrmion has icosahedral symmetry, and the shapes are shown to fit a remarkable sequence defined by a geometric energy minimization (GEM) rule. We also calculate the energies and sizes to within at least a few percent accuracy. These calculations provide the basis for a future investigation of the low energy vibrational modes of skyrmions and hence the possibility of testing the Skyrme model against experiment.Comment: latex, 9 pages, 1 figure (fig1.gif