19,281 research outputs found
Recommended from our members
Shopping for food: lessons from a London borough
Purpose – This paper aims to measure access to food in an inner London borough. Design/methodology/approach – There were six phases, which included designing food baskets, consultation with local residents and a shop survey. Recognising the cultural make-up of the borough food baskets and menus were developed for four key communities, namely: White British, Black Caribbean, Turkish, and Black African. Three areas were identified for the study and shopping hubs identified with a 500-metre radius from a central parade of shops. Findings – The findings paint an intricate web of interactions ranging from availability in shops to accessibility and affordability being key issues for some groups. It was found that in the areas studied there was availability of some key healthy items, namely fresh fruit and vegetables, but other items such as: fresh meat and poultry, fish, lower fat dairy foods, high fibre pasta and brown rice were not available. Access was found to be defined, by local people, as more extensive than just physical distance to/from shops – for many shopping was made more difficult by having to use taxis and inconvenient buses. Small shops were important in delivering healthy food options to communities in areas of deprivation and were judged to offer a better range and more appropriate food than the branches of the major supermarket chains. Research limitations/implications – The importance of monitoring the impact of shops and shop closures on healthy food availability is emphasised. From a policy perspective the findings suggest that approaches based on individual agency need to be balanced with upstream public health nutrition approaches in order to influence the options available. Originality/value – The paper is arguably the first to examine and dissect the issue of food availability and accessibility in the inner London borough in question, especially in the light of its proposed redevelopment for the London Olympics in 2012
Dynamic airfoil stall investigations
Experimental and computational investigations of the dynamic stall phenomenon continue to attract the attention of various research groups in the major aeronautical research laboratories. There are two reasons for this continued research interest. First, the occurrence of dynamic stall on the retreating blade of helicopters imposes a severe performance limitation and thus suggests to search for ways to delay the onset of dynamic stall. Second, the lift enhancement prior to dynamic stall presents an opportunity to achieve enhanced maneuverability of fighter aircraft. A description of the major parameters affecting dynamic stall and lift and an evaluation of research efforts prior to 1988 has been given by Carr. In this paper the authors' recent progress in the development of experimental and computational methods to analyze the dynamic stall phenomena occurring on NACA 0112 airfoils is reviewed. First, the major experimental and computational approaches and results are summarized. This is followed by an assessment of our results and an outlook toward the future
Quantum phase transitions in the Fermi-Bose Hubbard model
We propose a multi-band Fermi-Bose Hubbard model with on-site fermion-boson
conversion and general filling factor in three dimensions. Such a Hamiltonian
models an atomic Fermi gas trapped in a lattice potential and subject to a
Feshbach resonance. We solve this model in the two state approximation for
paired fermions at zero temperature. The problem then maps onto a coupled
Heisenberg spin model. In the limit of large positive and negative detuning,
the quantum phase transitions in the Bose Hubbard and Paired-Fermi Hubbard
models are correctly reproduced. Near resonance, the Mott states are given by a
superposition of the paired-fermion and boson fields and the Mott-superfluid
borders go through an avoided crossing in the phase diagram.Comment: 4 pages, 3 figure
Evolution of primordial black holes in Jordan-Brans-Dicke cosmology
We consider the evolution of primordial black holes in a generalyzed
Jordan-Brans-Dicke cosmological model where both the Brans-Dicke scalar field
and its coupling to gravity are dynamical functions determined from the
evolution equations. The evaporation rate for the black holes changes compared
to that in standard cosmology. We show that accretion of radiation can proceed
effectively in the radiation dominated era. The black hole lifetime shortens
for low initial mass, but increases for high initial mass, and is thus
considerably modified compared to the case of standard cosmology. We derive a
cut-off value for the initial black hole mass, below which primordial black
holes evaporate out in the radiation dominated era, and above which they
survive beyond the present era.Comment: 5 pages, Latex; uses MNRAS stylefiles; minor changes; accepted for
publication in MNRA
Internal stress wave measurements in solids subjected to lithotripter pulses
Semiconductor strain gauges were used to measure the internal strain along the axes of spherical and disk plaster specimens when subjected to lithotripter shock pulses. The pulses were produced by one of two lithotripters. The first source generates spherically diverging shock waves of peak pressure approximately 1 MPa at the surface of the specimen. For this source, the incident and first reflected pressure (P) waves in both sphere and disk specimens were identified. In addition, waves reflected by the disk circumference were found to contribute significantly to the strain fields along the disk axis. Experimental results compared favorably to a ray theory analysis of a spherically diverging shock wave striking either concretion. For the sphere, pressure contours for the incident P wave and caustic lines were determined theoretically for an incident spherical shock wave. These caustic lines indicate the location of the highest stresses within the sphere and therefore the areas where damage may occur. Results were also presented for a second source that uses an ellipsoidal reflector to generate a 30-MPa focused shock wave, more closely approximating the wave fields of a clinical extracorporeal lithotripter
Localized Asymmetric Atomic Matter Waves in Two-Component Bose-Einstein Condensates Coupled with Two Photon Microwave Field
We investigate localized atomic matter waves in two-component Bose-Einstein
condensates coupled by the two photon microwave field. Interestingly, the
oscillations of localized atomic matter waves will gradually decay and finally
become non-oscillating behavior even if existing coupling field. In particular,
atom numbers occupied in two different hyperfine spin states will appear
asymmetric occupations after some time evolution.Comment: 4 pages, 4 figure
- …