Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO

Magnetic 3d-ions doped into wide-gap oxides show signatures of room temperature ferromagnetism, although their concentration is two orders of magnitude smaller than that in conventional magnets. The prototype of these exceptional materials is Co-doped ZnO, for which an explanation of the room temperature ferromagnetism is still elusive. Here we demonstrate that magnetism originates from Co2+ oxygen-vacancy pairs with a partially filled level close to the ZnO conduction band minimum. The magnetic interaction between these pairs is sufficiently long-ranged to cause percolation at moderate concentrations. However, magnetically correlated clusters large enough to show hysteresis at room temperature already form below the percolation threshold and explain the current experimental findings. Our work demonstrates that the magnetism in ZnO:Co is entirely governed by intrinsic defects and a phase diagram is presented. This suggests a recipe for tailoring the magnetic properties of spintronics materials by controlling their intrinsic defects

Parental cultural models and resources for understanding mathematical achievement in culturally diverse school settings

This paper proposes that the theoretical concept of cultural models can offer useful insights into parental involvement in their child’s mathematical achievement and the resources they use to go about gaining information in culturally diverse learning settings. This examination takes place within a cultural-developmental framework and draws on the notion of cultural models to explicate parental understandings of their child’s mathematics achievement and what resources are used to make sense of this. Three parental resources are scrutinized: (a) the teacher, (b) examination test results, and (c) constructions of child development. The interviews with 22 parents revealed some ambiguity around the interpretation of these resources by the parent, which was often the result of incongruent cultural models held between the home and the school. The resources mentioned are often perceived as being unambiguous but show themselves instead to be highly interpretive because of the diversity of cultural models in existence in culturally diverse settings. Parents who are in minority or marginalized positions tend to have difficulties in interpreting cultural models held by school, thereby disempowering them to be parentally involved in the way the school would like

Assessing the predictive performance of population pharmacokinetic models for intravenous polymyxin B in critically ill patients

Polymyxin B (PMB) has reemerged as a last-line therapy for infections caused by multidrug-resistant gram-negative pathogens, but dosing is challenging because of its narrow therapeutic window and pharmacokinetic (PK) variability. Population PK (POPPK) models based on suitably powered clinical studies with appropriate sampling strategies that take variability into consideration can inform PMB dosing to maximize efficacy and minimize toxicity and resistance. Here we reviewed published PMB POPPK models and evaluated them using an external validation data set (EVD) of patients who are critically ill and enrolled in an ongoing clinical study to assess their utility. Seven published POPPK models were employed using the reported model equations, parameter values, covariate relationships, interpatient variability, parameter covariance, and unexplained residual variability in NONMEM (Version 7.4.3). The predictive ability of the models was assessed using prediction-based and simulation-based diagnostics. Patient characteristics and treatment information were comparable across studies and with the EVD (n = 40), but the sampling strategy was a main source of PK variability across studies. All models visually and statistically underpredicted EVD plasma concentrations, but the two-compartment models more accurately described the external data set. As current POPPK models were inadequately predictive of the EVD, creation of a new POPPK model based on an appropriately powered clinical study with an informed PK sampling strategy would be expected to improve characterization of PMB PK and identify covariates to explain interpatient variability. Such a model would support model-informed precision dosing frameworks, which are urgently needed to improve PMB treatment efficacy, limit resistance, and reduce toxicity in patients who are critically ill

Tutor and teacher timescapes : lessons from a home-school partnership

A partnership project was developed in which parents volunteered to support teachersin training years 1-3 children in computer skills at a primary school in a small, lowsocio-economic community. This article identifies the ways teachers and the &lsquo;tutors&rsquo;(as the volunteers were called) understood the value of the project. &lsquo;Being a teacher&rsquo;and &lsquo;being a volunteer&rsquo; were structured by different forms of social engagement,which in turn influenced the ways individuals were able to work with each other incollaborative processes. We argue that the discursive practices encoded in homeschool-community partnership rhetoric represent ruling-class ways of organising andnetworking that may be incompatible with those of people from low socio-economicbackgrounds. When such volunteers work in schools their attendance may be sporadicand short-term whereas teachers would like &lsquo;reliable&rsquo; ongoing commitment. Thismismatch wrought of teachers&rsquo; and volunteers&rsquo; differing everyday realities needs to beunderstood before useful models for partnerships in disadvantaged communities maybe realised.<br /

A Systems-Based Analysis of Mono- and Combination Therapy for Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections

Antimicrobial resistance is a global threat. As “proof-of-concept, ” we employed a system-based approach to identify patient, bacterial, and drug variables contributing to mortality in patients with carbapenem-resistant Klebsiella pneumoniae (CRKp) bloodstream infections exposed to colistin (COL) and ceftazidime-avibactam (CAZ/AVI) as mono- or combination therapies. Patients (n = 49) and CRKp isolates (n = 22) were part of the Consortium on Resistance Against Carbapenems in Klebsiella and other Enterobacteriaceae (CRACKLE-1), a multicenter, observational, prospective study of patients with carbapenem-resistant Enterobacterales (CRE) conducted between 2011 and 2016. Pharmacodynamic activity of mono- and combination drug concentrations was evaluated over 24 h using in vitro static time-kill assays. Bacterial growth and killing dynamics were estimated with a mechanism-based model. Random Forest was used to rank variables important for predicting

Notions of Well-Being, the State of Child Well-Being Research and the MYWEB Project

There has been a growing interest among academics, policy makers and practitioners in the subjective well-being of children and young people (CYP). The recognition of CYP’s rights to having a good childhood and good future life chances, coupled with the injunction from the New Sociology of Childhood to consult with CYP as active agents have resulted in an increasing number of studies on children and young people’s well-being at national and international levels. However, the design, content, and modes of data collection used in these surveys are influenced by the question of the extent to which the researchers view children and young people as similar or different to adults and which participatory models they are undertaking for the young people in the study. However, the design, content, and modes of data collection used in these surveys are influenced by a number of factors including conceptual underpinning of well-being, its measurement and participatory model(s) used by the researchers for children in those surveys. This chapter reviews these aspects before describing the structure of this book with summaries of each subsequent chapter