Suppression of carrier induced ferromagnetism by composition and spin fluctuations in diluted magnetic semiconductors

We suggest an approach to account for spatial (composition) and thermal fluctuations in "disordered" magnetic models (e.g. Heisenberg, Ising) with given spatial dependence of magnetic spin-spin interaction. Our approach is based on introduction of fluctuating molecular field (rather than mean field) acting between the spins. The distribution function of the above field is derived self-consistently. In general case this function is not Gaussian, latter asymptotics occurs only at sufficiently large spins (magnetic ions) concentrations $n_i$. Our approach permits to derive the equation for a critical temperature $T_c$ of ferromagnetic phase transition with respect to the above fluctuations. We apply our theory to the analysis of influence of composition fluctuations on $T_c$ in diluted magnetic semiconductors (DMS) with RKKY indirect spin-spin interaction.Comment: 6 pages, 2 figure

Realization of a Measurement of a Weak Value

We present the first realization of a measurement of a weak value, a concept recently introduced by Aharonov, Albert, and Vaidman (AAV). Our experiment uses a birefringent crystal to separate the two linear-polarization components of a laser beam by a distance small compared to the laser-beam waist. This weak measurement is followed by a strong measurement which translates the centroid of the beam by a distance far larger than the birefringence-induced separation. In addition, we present data corresponding to orthogonal initial and final states, for which the weak value is not defined. This interference effect may have application in the amplification and detection of weak effects

Realization of a Measurement of a Weak Value

We present the first realization of a measurement of a weak value, a concept recently introduced by Aharonov, Albert, and Vaidman (AAV). Our experiment uses a birefringent crystal to separate the two linear-polarization components of a laser beam by a distance small compared to the laser-beam waist. This weak measurement is followed by a strong measurement which translates the centroid of the beam by a distance far larger than the birefringence-induced separation. In addition, we present data corresponding to orthogonal initial and final states, for which the weak value is not defined. This interference effect may have application in the amplification and detection of weak effects

Effectiveness of peer educators on the uptake of mobile X-ray tuberculosis screening at homeless hostels: a cluster randomised controlled trial.

To compare current practice for encouraging homeless people to be screened for tuberculosis on a mobile digital X-ray unit in London, UK, with the additional use of volunteer peer educators who have direct experience of tuberculosis, homelessness or both

Dementia in rural settings: A scoping review exploring the personal experiences of people with dementia and their carers

Rural areas tend to be inhabited by more older people and thus have a higher prevalence of dementia. Combined with lower population densities and more sparse geography, rural areas pose numerous barriers and costs relating to support and resource provision. This may leave people with dementia in rural places at a significant disadvantage, leading to a heavy reliance on informal support networks. The present study explores the personal experiences of people living with dementia and carers living in rural areas, seeking to discover both benefits and challenges, as well as recommendations within the literature for improving the lives of those affected by dementia in rural areas. A scoping review following the framework of Arksey and O'Malley identified 60 studies that describe or discuss the personal experience of dementia (either by the person with dementia or carer), in relation to living in rural or remote geographical areas. Four overarching themes were derived, namely the possible benefits of living in a rural community (supportive rural communities), sources of strength described by people affected by dementia in rural areas (managing and coping), detrimental aspects of living in a rural community (rural community challenges) and difficulties with dementia care services. Three further themes yielded recommendations for improving the experience of dementia in rural areas. This review highlights some potential opportunities related to living in rural areas for people living with dementia. These often come with parallel challenges, reflecting a delicate balance between being well-supported and being in crisis for those living in rural areas. Given the limited access to formal services, supporting people with dementia in rural areas requires input and innovation from the people, organisations and services local to those communities

Observation of Velocity-Tuned Multiphoton Doppleron Resonances in Laser-Cooled Atoms

An atomic beam of Li was transversely cooled using an intense standing-wave radiation field. A dramatic change in the transverse velocity distribution was observed. Structure in the resulting velocity distribution was found to be due to velocity-tuned multiphoton Doppleron resonances. The force due to seven-photon resonances is clearly resolved in the data. The data are in good agreement with theoretical predictions

Observation of Velocity-Tuned Multiphoton Doppleron Resonances in Laser-Cooled Atoms

An atomic beam of Li was transversely cooled using an intense standing-wave radiation field. A dramatic change in the transverse velocity distribution was observed. Structure in the resulting velocity distribution was found to be due to velocity-tuned multiphoton Doppleron resonances. The force due to seven-photon resonances is clearly resolved in the data. The data are in good agreement with theoretical predictions