Quantum Turbulent Structure in Light

The infinite superpositions of random plane waves are known to be threaded with vortex line singularities which form complicated tangles and obey strict topological rules. We observe that within these structures a timelike axis appears to emerge with which we can define vortex velocities in a useful way: with both numerical simulations and optical experiments, we show that the statistics of these velocities match those of turbulent quantum fluids such as superfluid helium and atomic Bose-Einstein condensates. These statistics are shown to be independent of system scale. These results raise deep questions about the general nature of quantum chaos and the role of nonlinearity in the structure of turbulence.Comment: 4 pages, 2 figure

Ciproxifan, an H~3~ Receptor Antagonist, Improves Learning and Memory in the APP Mouse Model of Alzheimer's Disease

Mice that express the mutant form of the human amyloid precursor gene associated with early-onset familial Alzheimer's disease demonstrate memory deficits and amyloid plaques. We show here that ciproxifan, a prototypical antagonist of H~3~-type histamine receptors, alleviates two types of learning and memory impairments in such mice. These data support the idea that modulation of H~3~ receptors represents a viable therapeutic strategy in the treatment of Alzheimer's disease

Expansion Potential for Irrigation within the Mississippi Delta Region

17.6 million acres, or 73 percent, of the Mississippi Delta Region is currently cropland and possesses the physical characteristics of slope, texture and soil type which are recommended for irrigation. Economic feasibility of expanding irrigation by flood, furrow and center pivot methods were examined under 24 scenarios representing two sets of crop prices, yield levels, production costs, opportunity costs and six crop rotations. Irrigation was economically feasible for 56 to 100 percent of the cropland across all scenarios. Approximately 88 percent of the cropland can be economically irrigated with flood or furrow in its present form, 8 percent yield highest net returns if furrow irrigated following land forming and 4 percent can be economically irrigated only with center pivot systems

Microgastrinae (Hymenoptera: Braconidae) parasitizing Epirrita autumnata (Lepidoptera: Geometridae) larvae in Fennoscandia with description of Cotesia autumnatae Shaw, sp. n.

The microgastrine subset of hymenopteran parasitoids of the geometrid Epirrita autumnata is investigated in Fennoscandia. Ecology, including population dynamics, of the moth has been intensively studied in northern and mountainous Finland, Norway and Sweden. Recently supported hypotheses about the causes of its cyclic population dynamics stress the role of parasitoids, while the parasitoid complex with some 15 species is insufficiently known. The complex includes four solitarymicrogastrine species, Protapanteles anchisiades (Nixon), P. immunis (Wesmael), Cotesia salebrosa (Marshall) and C. autumnatae Shaw, sp. n. Here, we provide detailed figures for the latter, which is morphologically close to C. jucunda (Marshall), and describe the species as new to science. We also providemore general habitus figures of the other three species, as well as an identification key for the four species, aiming to aid recognition of these species by ecologists dealingwithmicrogastrine parasitoids of E. autumnata and their alternative geometrid hosts

Prevention or Control: Optimal Government Policies for Invasive Species Management

We present a conceptual, but empirically applicable, model for determining the optimal allocation of resources between exclusion and control activities for managing an invasive species with an uncertain discovery time. This model is used to investigate how to allocate limited resources between activities before and after the first discovery of an invasive species and the effects of the characteristics of an invasive species on limited resource allocation. The optimality conditions show that it is economically efficient to spend a larger share of outlays for exclusion activities before, rather than after, a species is first discovered, up to a threshold point. We also find that, after discovery, more exclusionary measures and fewer control measures are optimal, when the pest population is less than a threshold. As the pest population increases beyond this threshold, the exclusionary measures are no longer optimal. Finally, a comparative dynamic analysis indicates that the efficient level of total expenditures on preventive and control measures decreases with the level of the invasive species stock and increases with the intrinsic population growth rate, the rate of additional discoveries avoided, and the maximum possible pest population.invasive species, exclusion, control, eradication, public expenditures, Environmental Economics and Policy, Resource /Energy Economics and Policy,

Large fluctuations and irreversibility in nonequilibrium systems.

Large rare fluctuations in a nonequilibrium system are investigated theoretically and by analogue electronic experiment. It is emphasized that the optimal paths calculated via the eikonal approximation of the Fokker-Planck equation can be identified with the locus of the ridges of the prehistory probability distributions which can be calculated and measured experimentally for paths terminating at a given final point in configuration sspace. The pattern of optimal paths and its singularities, such as caustics, cusps and switching lines has been calculated and measured experimentally for a periodically driven overdamped oscillator, yielding results that are shown to be in good agreement with each other

High electrical conductance enhancement in Au-nanoparticle decorated sparse single-wall carbon nanotube networks

The authors thank the Engineering and Physical Science Research Council for funding through the Imperial College London/Queen Mary Unive

A phase transition in a system driven by coloured noise

For a system driven by coloured noise, we investigate the activation energy of escape, and the dynamics during the escape. We have performed analogue experiments to measure the change in activation energy as the power spectrum of the noise varies. An adiabatic approach based on path integral theory allows us to calculate analytically the critical value at which a phase transition in the activation energy occurs