Bifurcated polarization rotation in bismuth-based piezoelectrics

ABO3 perovskite-type solid solutions display a large variety of structural and physical properties, which can be tuned by chemical composition or external parameters such as temperature, pressure, strain, electric, or magnetic fields. Some solid solutions show remarkably enhanced physical properties including colossal magnetoresistance or giant piezoelectricity. It has been recognized that structural distortions, competing on the local level, are key to understanding and tuning these remarkable properties, yet, it remains a challenge to experimentally observe such local structural details. Here, from neutron pair-distribution analysis, a temperature-dependent 3D atomic-level model of the lead-free piezoelectric perovskite Na0.5Bi0.5TiO3 (NBT) is reported. The statistical analysis of this model shows how local distortions compete, how this competition develops with temperature, and, in particular, how different polar displacements of Bi3+ cations coexist as a bifurcated polarization, highlighting the interest of Bi-based materials in the search for new lead-free piezoelectrics

Effectiveness of a Perceived Solid Barrier as an Exclusion Fence to Prevent White-Tailed Deer Damage

We hypothesized that a visually solid barrier of cloth would provide an effective exclusion fence for free ranging white-tailed deer (Odocoileus virginianus). Three plots consisting of 2, 10 m x 10 m squares were established in pastures. Data were collected daily for consumption of com provided (2.27 kg) and events recorded by infrared game monitors. Following construction of the burlap fence at 1.7 m height, corn consumption decreased (0.07 ± 0.01 kg/day, P \u3c .001). The number of Infrared monitor events recorded also decreased within the enclosures (2.13 ± 0.04 events/day, P \u3c .001) compared to controls (46.0 ± 2.2 events/day). During the second stage of the experiment, two of the three plots were reestablished 45 days later. Fence heights began at 65 cm and were raised 15 cm each 5 days, until reaching 1.7 m. At 1.7 m, corn consumption decreased by 30% (1.56 ± 0.23 kg/day, P \u3c .01). The number of infrared monitor-recorded events was also lower at fence heights \u3e65 cm (P \u3c .03). Results indicate that a visually solid barrier has potential to be an effective exclusion fence

Effectiveness of a White-Tailed Deer Exclusion Fence Based on Traction Limitations of the Hoof: The Slipper Fence

We hypothesized that an exclusion fence could be devised to capitalize on traction limitations of the hooves of white-tailed deer (Odocoileus virginianus). Hexagonal plots (9.8 m wide) enclosed by a 2.4 m field fence with two openings (4.9 m) were established. Data were collected daily on consumption of corn provided (2.27 kg) and events recorded by infrared monitors (IR) for treatment and control sites. Five-day treatment periods consisted of test panels (4.9 m x 2.4 m) placed in plot openings at 0°, 5° and 10° slopes, and lubricant applied at the 10° slope. Deer consumed all corn provided at control sites. At the 10 ° slope, daily corn consumption decreased (1.50 kg ± 0 .26, p \u3c .0 l ), and IR events were lower (p \u3c .01) at treatment sites (23.6 ± 3.2) compared to controls (50.3 ± 9.6). With the addition of a lubricant, corn consumption decreased further (p \u3c .001) to 0. 17 kg ± 0.03, and IR recorded events were lower (p \u3c .001) at treatment sites (6.58 ± 0 .89) compared to controls (44.8 ± 3.1). Results of this study indicate that traction limitation of the hoof can be exploited

The Potential of Texture as a Deer Deterrent: The Slime Effect

We examined the potential of altering the surface texture of plant material as a potential deterrent to consumption by white-tailed deer. Two u-shaped garden plots were divided into 16, uniform plots (2.2mx4.3m) each containing approximately 50 chrysanthemums (C. morifolium). The plots were randomly assigned to one of the treatments or as a control. Immediately after planting, ten plants were randomly selected and marked within each plot. Plants were misted and treatments applied by hand broadcast. Treatments consisted of methyl cellulose (38.2g) and two-levels of a proprietary polymer (9. lg and 45.5g). Upon contact with water, methyl cellulose became a viscous slime while the proprietary polymer was similar to gelatin. Each substance was visible on the plants throughout the study. Bite marks were counted on the ten marked plants within each plot, on 4 occasions at 3-day intervals. None of the treatments were effective in deterring deer from consuming plant material. Differences were noted among plot locations, suggesting deer entered the garden predominantly from a single general direction and consumed forages most readily available

KIC 10080943: a binary star with two γ Doradus/δ Scuti hybrid pulsators. Analysis of the g modes

We use 4 yr of Kepler photometry to study the non-eclipsing spectroscopic binary KIC 10080943. We find both components to be γ Doradus/δ Scuti hybrids, which pulsate in both p and g modes. We present an analysis of the g modes, which is complicated by the fact that the two sets of l = 1 modes partially overlap in the frequency spectrum. Nevertheless, it is possible to disentangle them by identifying rotationally split doublets from one component and triplets from the other. The identification is helped by the presence of additive combina- tion frequencies in the spectrum that involve the doublets but not the triplets. The rotational splittings of the multiplets imply core rotation periods of about 11 and 7 d in the two stars. One of the stars also shows evidence of l = 2 modes

Radiation of Neutron Stars Produced by Superfluid Core

We find that neutron star interior is transparent for collisionless electron sound, the same way as it is transparent for neutrinos. In the presence of magnetic field the electron sound is coupled with electromagnetic radiation and form the fast magnetosonic wave. We find that electron sound is generated by superfluid vortices in the stellar core. Thermally excited helical vortex waves produce fast magnetosonic waves in the stellar crust which propagate toward the surface and transform into outgoing electromagnetic radiation. The vortex radiation has the spectral index -0.45 and can explain nonthermal radiation of middle-aged pulsars observed in the infrared, optical and hard X-ray bands. The radiation is produced in the stellar interior which allows direct determination of the core temperature. Comparing the theory with available spectra observations we find that the core temperature of the Vela pulsar is T=8*10^8K, while the core temperature of PSR B0656+14 and Geminga exceeds 2*10^8K. This is the first measurement of the temperature of a neutron star core. The temperature estimate rules out equation of states incorporating Bose condensations of pions or kaons and quark matter in these objects. Based on the temperature estimate and cooling models we determine the critical temperature of triplet neutron superfluidity in the Vela core Tc=(7.5\pm 1.5)*10^9K which agrees well with recent data on behavior of nucleon interactions at high energies. Another finding is that in the middle aged neutron stars the vortex radiation, rather then thermal conductivity, is the main mechanism of heat transfer from the stellar core to the surface. Electron sound opens a perspective of direct spectroscopic study of superdense matter in the neutron star interiors.Comment: 43 pages, 7 figures, to appear in Astrophysical Journa

Eradication of poliomyelitis in South Africa

An international campaign under the leadership of the World Health Organisation is underway to eradicate polio from the world by the year 2000. South Africa may already be free of polio. However, to ensure eradication we need to move from a polio control programme to a polio eradication programme. This necessitates the institution of a surveillance programme for acute flaccid paralysis (AFP) and improvement of the delivery of polio vaccine. All children with AFP (including those with suspected GuillainBarre syndrome) should be investigated with stool culture to exclude polio. Primary care services need strengthening so that oral polio vaccine coverage greater than 90% is achieved in all regions by all authorities. Outbreak response activities need to be developed. Consideration needs to be given to national immunisation days and mopping-up activities

Is the Cygnus Loop two supernova remnants?

The Cygnus Loop is classified as a middle-aged supernova remnant (SNR) located below the Galactic equator (l=74, b=-8.6) and 770 pc away from us. Its large size and little confusion with Galactic emission makes it an ideal test ground for evolutionary and structural theories of SNRs. New radio continuum mapping of the Cygnus Loop at 2695 MHz with the Effelsberg 100-m telescope provides indications that the Cygnus Loop consists of two separate SNRs. Combining this result with data from the literature we argue that a secondary SNR exists in the south with a recently detected neutron star close to its center. Two interacting SNRs seem to be the best explanation to account for the Cygnus Loop observations at all wavelengths.Comment: 4 pages, 2 figures, Astron. Astrophys., accepte

Underdamped modes in a hydrodynamically coupled microparticle system

When micron-sized particles are trapped in a linear periodic array, for example, by using optical tweezers, they interact only through the hydrodynamic forces between them. This couples the motion of the spheres and it has been predicted that an extended system might behave as an elastic medium that could support underdamped propagating waves. In practice, these underdamped modes can be observed only with massive particles in very stiff traps and very low viscosity fluids. We have been able to realize these conditions by trapping water droplets in air. Even with a system of just two particles we were able to observe the coupled oscillatory motion predicted: underdamping of the symmetric (collective) mode and overdamping of the asymmetric (relative) mode