Oscillating magnetoresistance in diluted magnetic semiconductor barrier structures

Ballistic spin polarized transport through diluted magnetic semiconductor (DMS) single and double barrier structures is investigated theoretically using a two-component model. The tunneling magnetoresistance (TMR) of the system exhibits oscillating behavior when the magnetic field are varied. An interesting beat pattern in the TMR and spin polarization is found for different NMS/DMS double barrier structures which arises from an interplay between the spin-up and spin-down electron channels which are splitted by the s-d exchange interaction.Comment: 4 pages, 6 figures, submitted to Phys. Rev.

Finding a voice: A figured worlds approach to theorising young children's identities

This article explores some of the ways in which children’s ethnic identities have been conceptualised by sociocultural and critical race theory and the potential of the ‘figured worlds’ literature in helping to theorise the responses of young children to the cultural and educational worlds they encounter. Using some vignettes drawn from the author’s ethnographic study of the ethnic identities of a group of 3- and 4-year-old White British and British Pakistani children in a kindergarten in the north of England, the article explores the potential of a figured worlds analysis in understanding how the children respond to some of the experiences of the kindergarten and in understanding how they seek to make sense of their identities. The article concludes that while structural and cultural factors shaped the ways in which the children engaged or did not engage in the social and educational practices of the kindergarten and played a very significant part in how they viewed themselves and viewed others, the children were not silent observers of what the world offered or did not offer them. A dialogic self was evident that authored and tried to make sense of the world, but, in so doing, designated identities meant that only particular figured worlds were available to children for much of the time. It is argued that what a figured worlds reading offers is a means of seeking to uncover and theorise the complex ways in which young children experience and perform their identities and respond to the social and educational practices in particular contexts. This is seen as having value in providing a framework for early childhood academics and educators to work together to support children in exploring alternative figured identities that challenge, alleviate and transform the constraints that positional identities often seem to impose on them

The electrophotonic silicon biosensor

The emergence of personalized and stratified medicine requires label-free and low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high sensitivity analysis with scalable, low-cost manufacturing technology but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here, we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomolecules. Our electro-photonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical processes enables site selective immobilization of different biomolecules, here single stranded DNA, onto individual microrings within a sensor array. The combination of photonic and electrochemical characterization of molecules bound to the sensor surface also provides direct quantification of binding density and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the micro-scale

Anaerobic animals from an ancient, anoxic ecological niche

Tiny marine animals that complete their life cycle in the total absence of light and oxygen are reported by Roberto Danovaro and colleagues in this issue of BMC Biology. These fascinating animals are new members of the phylum Loricifera and possess mitochondria that in electron micrographs look very much like hydrogenosomes, the H2-producing mitochondria found among several unicellular eukaryotic lineages. The discovery of metazoan life in a permanently anoxic and sulphidic environment provides a glimpse of what a good part of Earth's past ecology might have been like in 'Canfield oceans', before the rise of deep marine oxygen levels and the appearance of the first large animals in the fossil record roughly 550-600 million years ago. The findings underscore the evolutionary significance of anaerobic deep sea environments and the anaerobic lifestyle among mitochondrion-bearing cells. They also testify that a fuller understanding of eukaryotic and metazoan evolution will come from the study of modern anoxic and hypoxic habitats

Biomarker-guided implementation of the KDIGO guidelines to reduce the occurrence of acute kidney injury in patients after cardiac surgery (PrevAKI-multicentre) : protocol for a multicentre, observational study followed by randomised controlled feasibility trial

Acute kidney injury (AKI) is a frequent complication after cardiac surgery with adverse short-term and long-term outcomes. Although prevention of AKI (PrevAKI) is strongly recommended, the optimal strategy is uncertain. The Kidney Disease: Improving Global Outcomes (KDIGO) guideline recommended a bundle of supportive measures in high-risk patients. In a single-centre trial, we recently demonstrated that the strict implementation of the KDIGO bundle significantly reduced the occurrence of AKI after cardiac surgery. In this feasibility study, we aim to evaluate whether the study protocol can be implemented in a multicentre setting in preparation for a large multicentre trial. We plan to conduct a prospective, observational survey followed by a randomised controlled, multicentre, multinational clinical trial including 280 patients undergoing cardiac surgery with cardiopulmonary bypass. The purpose of the observational survey is to explore the adherence to the KDIGO recommendations in routine clinical practice. The second phase is a randomised controlled trial. The objective is to investigate whether the trial protocol is implementable in a large multicentre, multinational setting. The primary endpoint of the interventional part is the compliance rate with the protocol. Secondary endpoints include the occurrence of any AKI and moderate/severe AKI as defined by the KDIGO criteria within 72 hours after surgery, renal recovery at day 90, use of renal replacement therapy (RRT) and mortality at days 30, 60 and 90, the combined endpoint major adverse kidney events consisting of persistent renal dysfunction, RRT and mortality at day 90 and safety outcomes. The PrevAKI multicentre study has been approved by the leading Research Ethics Committee of the University of Münster and the respective Research Ethics Committee at each participating site. The results will be used to design a large, definitive trial. Trial registration number NCT03244514

Quantification of Retrograde Axonal Transport in the Rat Optic Nerve by Fluorogold Spectrometry

PURPOSE: Disturbed axonal transport is an important pathogenic factor in many neurodegenerative diseases, such as glaucoma, an eye disease characterised by progressive atrophy of the optic nerve. Quantification of retrograde axonal transport in the optic nerve usually requires labour intensive histochemical techniques or expensive equipment for in vivo imaging. Here, we report on a robust alternative method using Fluorogold (FG) as tracer, which is spectrometrically quantified in retinal tissue lysate. METHODS: To determine parameters reflecting the relative FG content of a sample FG was dissolved in retinal lysates at different concentrations and spectra were obtained. For validation in vivo FG was injected uni- or bilaterally into the superior colliculus (SC) of Sprague Dawley rats. The retinal lysate was analysed after 3, 5 and 7 days to determine the time course of FG accumulation in the retina (n = 15). In subsequent experiments axona transport was impaired by optic nerve crush (n = 3), laser-induced ocular hypertension (n = 5) or colchicine treatment to the SC (n = 10). RESULTS: Spectrometry at 370 nm excitation revealed two emission peaks at 430 and 610 nm. We devised a formula to calculate the relative FG content (c(FG)), from the emission spectrum. c(FG) is proportional to the real FG concentration as it corrects for variations of retinal protein concentration in the lysate. After SC injection, c(FG) monotonously increases with time (p = 0.002). Optic nerve axonal damage caused a significant decrease of c(FG) (crush p = 0.029; hypertension p = 0.025; colchicine p = 0.006). Lysates are amenable to subsequent protein analysis. CONCLUSIONS: Spectrometrical FG detection in retinal lysates allows for quantitative assessment of retrograde axonal transport using standard laboratory equipment. It is faster than histochemical techniques and may also complement morphological in vivo analyses

The professional knowledge that counts in Australian contemporary early childhood teacher education

Australia is typical of many western countries where the provision of quality early childhood services has become a government priority. The government initiatives in Australia include repeated demands for 'well-qualified' early childhood educators. As a result of these demands the preservice preparation of early childhood educators is under intense scrutiny. This scrutiny raises many questions regarding the knowledge base considered to be essential for early childhood educators and leads to further questions about who has the authority to produce this knowledge. This article explores these questions by firstly examining some of the ways Australian early childhood teacher education is situated within the current knowledge environment. This is followed by a discussion regarding the debates about what early childhood educators 'need to know'. The third section of the article traces some of the historical features of Australian early childhood teacher education, for the author argues that contemporary questions about 'which' knowledge is to be included in early childhood teacher education are best understood alongside their historical precedents. The article concludes by considering the implications of the debates for contemporary early childhood teacher education and suggests that a way forward involves reconsidering the traditional binary between theory and practical knowledge