Room temperature electron spin relaxation in GaInNAs multiple quantum wells at 1.3 mu m

The authors report a direct measurement of electron spin relaxation in GaInNAs semiconductor multiple quantum wells at room temperature. Multiple quantum wells of widths 5.8, 7, and 8 nm exhibiting excitonic absorption around 1.3 mu m have been studied. Spin relaxation times were found to increase with well width in the range of 77-133 ps. The spin relaxation time dependence on first electron confinement energy suggests the Elliot-Yafet mechanism [A. Tackeuchi , Physica B 272, 318 (1999)] as the dominant relaxation process. (c) 2006 American Institute of Physics.</p

First-principles modeling of temperature and concentration dependent solubility in the phase separating Fex_xCu1−x_{1-x} alloy system

We present a novel cluster-expansion (CE) approach for the first-principles modeling of temperature and concentration dependent alloy properties. While the standard CE method includes temperature effects only via the configurational entropy in Monte Carlo simulations, our strategy also covers the first-principles free energies of lattice vibrations. To this end, the effective cluster interactions of the CE have been rendered genuinely temperature dependent, so that they can include the vibrational free energies of the input structures. As a model system we use the phase-separating alloy Fe-Cu with our focus on the Fe-rich side. There, the solubility is derived from Monte Carlo simulations, whose precision had to be increased by averaging multiple CEs. We show that including the vibrational free energy is absolutely vital for the correct first-principles prediction of Cu solubility in the bcc Fe matrix: The solubility tremendously increases and is now in quantitative agreement with experimental findings

On the edge of a new frontier: Is gerontological social work in the UK ready to meet twenty-first-century challenges?

This article is available open access through the publisher’s website. Copyright @ 2013 The Authors.This article explores the readiness of gerontological social work in the UK for meeting the challenges of an ageing society by investigating the focus on work with older people in social work education and the scope of gerontological social work research. The discussion draws on findings from two exploratory studies: a survey of qualifying master's programmes in England and a survey of the content relating to older people over a six-year period in four leading UK social work journals. The evidence from master's programmes suggests widespread neglect of ageing in teaching content and practice learning. Social work journals present a more nuanced picture. Older people emerge within coverage of generic policy issues for adults, such as personalisation and safeguarding, and there is good evidence of the complexity of need in late life. However, there is little attention to effective social work interventions, with an increasingly diverse older population, or to the quality of gerontological social work education. The case is made for infusing content on older people throughout the social work curriculum, for extending practice learning opportunities in social work with older people and for increasing the volume and reporting of gerontological social work research.Brunel Institute for Ageing Studie

Problem gambling: a suitable case for social work?

Problem gambling attracts little attention from health and social care agencies in the UK. Prevalence surveys suggest that 0.6% of the population are problem gamblers and it is suggested that for each of these individuals, 10–17 other people, including children and other family members, are affected. Problem gambling is linked to many individual and social problems including: depression, suicide, significant debt, bankruptcy, family conflict, domestic violence, neglect and maltreatment of children and offending. This makes the issue central to social work territory. Yet, the training of social workers in the UK has consistently neglected issues of addictive behaviour. Whilst some attention has been paid in recent years to substance abuse issues, there has remained a silence in relation to gambling problems. Social workers provide more help for problems relating to addictions than other helping professions. There is good evidence that treatment, and early intervention for gambling problems, including psycho-social and public health approaches, can be very effective. This paper argues that problem gambling should be moved onto the radar of the social work profession, via inclusion on qualifying and post-qualifying training programmes and via research and dissemination of good practice via institutions such as the Social Care Institute for Excellence (SCIE). Keywords: problem gambling; addictive behaviour; socia

A whole-cell biosensor for the detection of gold

Geochemical exploration for gold (Au) is becoming increasingly important to the mining industry. Current processes for Au analyses require sampling materials to be taken from often remote localities. Samples are then transported to a laboratory equipped with suitable analytical facilities, such as Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) or Instrumental Neutron Activation Analysis (INAA). Determining the concentration of Au in samples may take several weeks, leading to long delays in exploration campaigns. Hence, a method for the on-site analysis of Au, such as a biosensor, will greatly benefit the exploration industry. The golTSB genes from Salmonella enterica serovar typhimurium are selectively induced by Au(I/III)-complexes. In the present study, the golTSB operon with a reporter gene, lacZ, was introduced into Escherichia coli. The induction of golTSB::lacZ with Au(I/III)-complexes was tested using a colorimetric β-galactosidase and an electrochemical assay. Measurements of the β-galactosidase activity for concentrations of both Au(I)- and Au(III)-complexes ranging from 0.1 to 5 µM (equivalent to 20 to 1000 ng g⁻¹ or parts-per-billion (ppb)) were accurately quantified. When testing the ability of the biosensor to detect Au(I/III)-complexes(aq) in the presence of other metal ions (Ag(I), Cu(II), Fe(III), Ni(II), Co(II), Zn, As(III), Pb(II), Sb(III) or Bi(III)), cross-reactivity was observed, i.e. the amount of Au measured was either under- or over-estimated. To assess if the biosensor would work with natural samples, soils with different physiochemical properties were spiked with Au-complexes. Subsequently, a selective extraction using 1 M thiosulfate was applied to extract the Au. The results showed that Au could be measured in these extracts with the same accuracy as ICP-MS (P<0.05). This demonstrates that by combining selective extraction with the biosensor system the concentration of Au can be accurately measured, down to a quantification limit of 20 ppb (0.1 µM) and a detection limit of 2 ppb (0.01 µM).Carla M. Zammit, Davide Quaranta, Shane Gibson, Anita J. Zaitouna, Christine Ta, Joël Brugger, Rebecca Y. Lai, Gregor Grass, Frank Reit

Edging your bets: advantage play, gambling, crime and victimisation

Consumerism, industrial development and regulatory liberalisation have underpinned the ascendance of gambling to a mainstream consumption practice. In particular, the online gambling environment has been marketed as a site of ‘safe risks’ where citizens can engage in a multitude of different forms of aleatory consumption. This paper offers a virtual ethnography of an online ‘advantage play’ subculture. It demonstrates how advantage players have reinterpreted the online gambling landscape as an environment saturated with crime and victimisation. In this virtual world, advantage play is no longer simply an instrumental act concerned with profit accumulation to finance consumer desires. Rather, it acts as an opportunity for individuals to engage in a unique form of edgework, whereby the threat to one’s well-being is tested through an ability to avoid crime and victimisation. This paper demonstrates how mediated environments may act as sites for edgeworking and how the potential for victimisation can be something that is actively engaged with

MHC class II-restricted antigen presentation by plasmacytoid dendritic cells drives proatherogenic T cell immunity

Background—Plasmacytoid dendritic cells (pDCs) bridge innate and adaptive immune responses and are important regulators of immuno-inflammatory diseases. However, their role in atherosclerosis remains elusive. Methods and Results—Here, we used genetic approaches to investigate the role of pDCs in atherosclerosis. Selective pDC deficiency in vivo was achieved using CD11c-Cre × Tcf4–/flox bone marrow transplanted into Ldlr–/– mice. Compared with control Ldlr–/– chimeric mice, CD11c-Cre × Tcf4–/flox mice had reduced atherosclerosis levels. To begin to understand the mechanisms by which pDCs regulate atherosclerosis, we studied chimeric Ldlr–/– mice with selective MHCII deficiency on pDCs. Significantly, these mice also developed reduced atherosclerosis compared with controls without reductions in pDC numbers or changes in conventional DCs. MHCII-deficient pDCs showed defective stimulation of apolipoprotein B100–specific CD4+ T cells in response to native low-density lipoprotein, whereas production of interferon-α was not affected. Finally, the atheroprotective effect of selective MHCII deficiency in pDCs was associated with significant reductions of proatherogenic T cell–derived interferon-γ and lesional T cell infiltration, and was abrogated in CD4+ T cell–depleted animals. Conclusions—This study supports a proatherogenic role for pDCs in murine atherosclerosis and identifies a critical role for MHCII-restricted antigen presentation by pDCs in driving proatherogenic T cell immunity

Geogenic factors as drivers of microbial community diversity in soils overlying polymetallic deposits

This study shows that the geogenic factors landform, lithology, and underlying mineral deposits (expressed by elevated metal concentrations in overlying soils) are key drivers of microbial community diversity in naturally metal-rich Australian soils with different land uses, i.e., agriculture versus natural bushland. One hundred sixty-eight soil samples were obtained from two metal-rich provinces in Australia, i.e., the Fifield Au-Pt field (New South Wales) and the Hillside Cu-Au-U rare-earth-element (REE) deposit (South Australia). Soils were analyzed using three-domain multiplex terminal-restriction-fragment-length-polymorphism (M-TRFLP) and PhyloChip microarrays. Geogenic factors were determined using field-mapping techniques and analyses of >50 geochemical parameters. At Fifield, microbial communities differed significantly with geogenic factors and equally with land use (P 0.2 m) differed significantly with lithology and mineral deposit (P < 0.05). Across both sites, elevated metal contents in soils overlying mineral deposits were selective for a range of bacterial taxa, most importantly Acidobacteria, Bacilli, Betaproteobacteria, and Epsilonproteobacteria. In conclusion, long-term geogenic factors can be just as important as land use in determining soil microbial community diversity

Mammalian Innate Immune Response to a Leishmania-Resident RNA Virus Increases Macrophage Survival to Promote Parasite Persistence.

Some strains of the protozoan parasite Leishmania guyanensis (L.g) harbor a viral endosymbiont called Leishmania RNA virus 1 (LRV1). LRV1 recognition by TLR-3 increases parasite burden and lesion swelling in vivo. However, the mechanisms by which anti-viral innate immune responses affect parasitic infection are largely unknown. Upon investigating the mammalian host's response to LRV1, we found that miR-155 was singularly and strongly upregulated in macrophages infected with LRV1+ L.g when compared to LRV1- L.g. LRV1-driven miR-155 expression was dependent on TLR-3/TRIF signaling. Furthermore, LRV1-induced TLR-3 activation promoted parasite persistence by enhancing macrophage survival through Akt activation in a manner partially dependent on miR-155. Pharmacological inhibition of Akt resulted in a decrease in LRV1-mediated macrophage survival and consequently decreased parasite persistence. Consistent with these data, miR-155-deficient mice showed a drastic decrease in LRV1-induced disease severity, and lesional macrophages from these mice displayed reduced levels of Akt phosphorylation