Automatic kelvin probe compatible with ultrahigh vacuum

This article describes a new type of in situ ultrahigh‐vacuum compatible kelvin probe based on a voice‐coil driving mechanism. This design exhibits several advantages over conventional mechanical feed‐through and (in situ) piezoelectric devices in regard to the possibility of multiple probe geometry, flexibility of probe geometry, amplitude of oscillation, and pure parallel vibration. Automatic setup and constant spacing features are achieved using a digital‐to‐analog converter (DAC) steered offset potential. The combination of very low driver noise pick‐up and data‐acquisition system (DAS) signal processing techniques results in a work function (wf  ) resolution, under optimal conditions, of <0.1 meV. Due to its high surface sensitivity and compatibility with standard sample cleaning and analysis techniques this design has numerous applications in surface studies, e.g., adsorption kinetics, sample topography and homogeneity, sputter profiles, etc. For semiconductor specimens the high wf resolution makes it eminently suitable for surface photovoltage (SPV) spectroscopy

Predicting infectious complications in neutropenic children and young people with cancer (IPD protocol)

<p>Abstract</p> <p>Background</p> <p>A common and potentially life-threatening complication of the treatment of childhood cancer is infection, which frequently presents as fever with neutropenia. The standard management of such episodes is the extensive use of intravenous antibiotics, and though it produces excellent survival rates of over 95%, it greatly inconveniences the three-fourths of patients who do not require such aggressive treatment. There have been a number of studies which have aimed to develop risk prediction models to stratify treatment. Individual participant data (IPD) meta-analysis in therapeutic studies has been developed to improve the precision and reliability of answers to questions of treatment effect and recently have been suggested to be used to answer questions regarding prognosis and diagnosis to gain greater power from the frequently small individual studies.</p> <p>Design</p> <p>In the IPD protocol, we will collect and synthesise IPD from multiple studies and examine the outcomes of episodes of febrile neutropenia as a consequence of their treatment for malignant disease. We will develop and evaluate a risk stratification model using hierarchical regression models to stratify patients by their risk of experiencing adverse outcomes during an episode. We will also explore specific practical and methodological issues regarding adaptation of established techniques of IPD meta-analysis of interventions for use in synthesising evidence derived from IPD from multiple studies for use in predictive modelling contexts.</p> <p>Discussion</p> <p>Our aim in using this model is to define a group of individuals at low risk for febrile neutropenia who might be treated with reduced intensity or duration of antibiotic therapy and so reduce the inconvenience and cost of these episodes, as well as to define a group of patients at very high risk of complications who could be subject to more intensive therapies. The project will also help develop methods of IPD predictive modelling for use in future studies of risk prediction.</p

Lecithin/sphingomyelin ratio and lamellar body count for fetal lung maturity: a meta-analysis

Abstract not availableAnouk E. Besnard, Soetinah A.M. Wirjosoekarto, Kimiko A. Broeze, Brent C. Opmeer, Ben Willem J. Mo

Treatment should be considered a competing risk when predicting natural conception in subfertile women

BACKGROUND Prediction of natural conception in subfertile couples can help to differentiate between couples who should have immediate treatment and couples who can aim for natural conception for some time. Natural conception rates are often estimated using standard techniques such as Kaplan–Meier or Cox proportional hazard models. These estimates can be biased by incorrect handling of data from women who start assisted reproductive technology therapy before the end of the follow-up period. This paper discusses the validity and the impact of the assumption of non-informative censoring as used in the Kaplan–Meier and Cox models. METHODS In a cohort of 5360 subfertile couples with suspected tubal pathology, the probability of natural conception and the prognostic value of additional tests for tubal pathology were estimated using traditional methods and with a competing risks analysis. RESULTS The estimated probability of natural conception within 3 years was almost 2-fold higher when assuming non-informative censoring compared with the competing risks model, 41 versus 22%. The prognostic value of tests was more conservative using the competing risks model than with the traditional methods, the fecundity rate ratio for Chlamydia antibody testing was 0.72 versus 0.67, for hysterosalpingography, 0.83 versus 0.71 and for diagnostic laparoscopy, 0.89 versus 0.74. CONCLUSIONS Given the improbable validity of the non-informative censoring assumption, the predictions of natural conception and of the prognostic value of tests are likely to be overestimated by the traditional analytic methods. We suggest the use of competing risks models as an alternative, more conservative, form of analysis when predicting natural conception and evaluating prognostic fertility tests.N. Van Geloven, K.A. Broeze, P.M.M. Bossuyt, A.H. Zwinderman, and B.W. Mo

Van innovatieve materialen naar innovatie: Nog veel onbenutte kansen

Materialen zijn de bouwstenen van producten en vormen daarmee de basis van veel innovatietrajecten. Er zijn echter nog veel onbenutte kansen. Door het gebruik van andere (nieuwe) materialen kunnen ontwerpproblemen worden opgelost en nieuwe mogelijkheden worden toegevoegd. De materiaalkeuze brengt gevolgen met zich mee op het gebied van de functionaliteit, vormvrijheid, esthetiek, duurzaamheid en constructie van een product. Vanuit deze cruciale rol van materialen in het productontwerpproces is het Innovatief Materialen Platform Twente (IMPT) opgericht. Het IMPT verzamelt en verspreidt kennis over innovatieve, dan wel weinig toegepaste (onbekende) materialen. In dit artikel wordt de aanpak van het IMPT project toegelicht. Hoe verbinden we eigenschappen van materialen aan toepassingen waar de markt om vraagt? En hoe zorgen we ervoor dat ontwerpers en bedrijven weten of ze wel, of juist niet voor een bepaald materiaal kunnen kiezen? Dit artikel van het Innovatief Mateialen Platform Twente (IMPT) is geschreven voor en gepubliceerd in het vakblad Product. In vervolgartikelen - ook in Product - komen diverse onderzochte materialen aan bod. &nbsp

How to deal with double partial verification when evaluating two index tests in relation to a reference test?

Research into the diagnostic accuracy of clinical tests is often hampered by single or double partial verification mechanisms, that is, not all patients have their disease status verified by a reference test, neither do all patients receive all tests under evaluation (index tests). We show methods that reduce verification bias introduced when omitting data from partially tested patients. Adjustment techniques are well established when there are no missing index tests and when the reference test is 'missing at random'. However, in practice, index tests tend to be omitted, and the choice of applying a reference test may depend on unobserved variables related to disease status, that is, verification may be missing not at random (MNAR). We study double partial verification in a clinical example from reproductive medicine in which we analyse the diagnostic values of the chlamydia antibody test and the hysterosalpingography in relation to a diagnostic laparoscopy. First, we plot all possible combinations of sensitivity and specificity of both index tests in two test ignorance regions. Then, we construct models in which we impose different assumptions for the verification process. We allow for missing index tests, study the influence of patient characteristics and study the accuracy estimates if an MNAR mechanism would operate. It is shown that data on tests used in the diagnostic process of the same population are preferably studied jointly and that the influence of an MNAR verification process was limited in a clinical study where more than half of the patients did not have the reference test.Nan van Geloven, Kimiko A. Broeze, Brent C. Opmeer, BenWillem Mol and Aeilko H. Zwinderma

Mitigating climate change through reduced food loss and waste

Agenda: Introduction to CCAFS and CGIAR: Why food loss and waste? - Lini Wollenberg The Food Loss and Waste Calculator and how it can be used to mitigate climate change - Jan Broeze Understanding Smallholder Farmers’ Post-Harvest Behaviors: Evidence from Malawi - Tabitha Nindi Effects of Amending Soil with Organic Matter on Population Change of Aspergillus flavus and Antagonistic Microbiome: and on Aflatoxin Contamination of Groundnut in Malawi - Norah Machinjiri Quantifying GHG emissions of agrifood chain and associated food loss and food waste in China - Li Xue A Stepping-Stone to the evidence base for the mitigation of N2O emission from reduced food loss and waste in China and Myanmar - Xia Liang Food waste reduction entrepreneurship initiative and associated impacts: a Life Cycle Sustainability Assessment - Daniele Matzembache

Individual patient data meta-analysis: a promising approach for evidence synthesis in reproductive medicine

Systematic reviews and accompanying meta-analyses are the cornerstones of evidence-based medicine. Systematic reviews summarize clinical evidence; meta-analyses provide summary estimates of the treatment effect or the diagnostic test accuracy. Although deemed to provide the highest level of evidence, their clinical value is limited as they can only summarize aggregated data. In these meta-analyses the true variability of the treatment effects cannot be explored to the desired extent, because the meta-analyses cannot distinguish between patients with different clinical profiles. Systematic reviews and meta-analyses based on individual patient data (IPD), described as the ‘gold standard’ for systematic reviews are a promising approach that might overcome these limitations. IPD meta-analyses allow treatment effects and diagnostic accuracy to be estimated at the level of relevant patient subgroups. This enables researchers to investigate the effectiveness of treatment in patients with different profiles. In this article, we address the opportunities of systematic reviews and meta-analyses using IPD in reproductive medicine. We discuss its potential based on three clinical examples: single versus double embryo transfer in IVF, the diagnosis of tubal pathology and the prognostic value of ovarian reserve tests. We propose to show potential advantages of IPD systematic reviews and meta-analyses in providing stratified clinical evidence, which could improve medical care.Kimiko A. Broeze, Brent C. Opmeer, Fulco van der Veen, Patrick M. Bossuyt, Siladitya Bhattacharya, and Ben W.J. Mo