We subject a falling cloud of cold cesium atoms to periodic kicks from a sinusoidal potential created by a vertical standing wave of laser light. By controllably accelerating the potential, we show quantum accelerator mode dynamics to be highly sensitive to the effective gravitational acceleration when close to specific, resonant values. This quantum sensitivity to a control parameter is remini...

In recent years there has been much interest in alternative sources of income for farmers. This is because economic theory suggests that demand for agricultural commodities is inelastic so that, as incomes in society as a whole increase, those of farmers do not necessarily keep pace Ð hence the current problems with falling real farm incomes. In contrast the demand for services is relatively el...

If a group of foragers distributes among resource patches according to the ideal free distribution, the relative number of foragers in each patch should match the relative amount of resource obtained there, unless deviations arise from factors such as incomplete information or interforager interference. In analogy to individual choice, such effects may produce undermatching—group distribution f...

Using ray theory, the Möbius shift of the (p-1)-order rainbow angle for a particle having an elliptical cross section is obtained to first order in the ellipticity as a function of the tilt of the ellipse with respect to the propagation direction of the incoming rays. The result is then adapted to the geometry of scattering of light rays from the sun by a falling water drop as a function of sun...

The experimental results on the falling down of scaled factorial moments in azimuthal variable φ is studied in some detail. It is shown that this phenomenon may be referred to the influence of transverse momentum conservation. The existing experimental data from DELPHI, EMU08, NA22 and UA1 are successfully explained. Various methods are proposed to partly eliminate this influence and rule out t...

BACKGROUND Falls amongst older people have been linked to reduced postural stability and slowed movement responses. The objective of this study was to examine differences in postural stability and the speed of response between young adults, low fall-risk older adults, and high fall-risk older adults during voluntary postural sway movements. METHODS Twenty-five young adults (25+/-4 years), and...

We present a Rayleigh-Taylor mixing rate simulation with an acceleration rate falling within the range of experiments. The simulation uses front tracking to prevent interfacial mass diffusion. We present evidence to support the assertion that the lower acceleration rate found in untracked simulations is caused, at least to a large extent, by a reduced buoyancy force due to numerical interfacial...

Each year, about one third of the population over 65 years of age experiences at least one fall (Perry, 1982). Assessment of the incidence of falls and the prevalence, intensity, and covariates of fear of falling among community-based elderly persons was conducted through interviews of 115 residents in a housing development (mean age = 78 years). Fifty-three percent reported having fallen in re...

In many retail markets, prices rise faster than they fall. We develop a model of search with learning to explain this phenomenon of asymmetric price adjustments. By extending our static game analysis to the dynamic setting, we demonstrate that asymmetric price adjustments arise naturally. When a positive cost shock occurs, all the searchers immediately learn the true state; the search intensity...

Umhlanga is a ceremony celebrating virginity. In South Africa, it is practiced, among others, by the Zulu ethnic group who live mainly in the province of KwaZulu Natal. After falling into relative disuse in the Zulu community, the practice of virginity testing made a comeback some 10 years ago at around the time of the country's first democratic election and coinciding with the period when the ...