Measuring storage and loss moduli using optical tweezers: broadband microrheology

We present an experimental procedure to perform broadband microrheological measurements with optical tweezers. A generalised Langevin equation is adopted to relate the time-dependent trajectory of a particle in an imposed flow to the frequency-dependent moduli of the complex fluid. This procedure allows us to measure the material linear viscoelastic properties across the widest frequency range achievable with optical tweezers.Comment: 5 pages, 3 figure

Characteristics of successful risk management in product design

The paper reports results of one of the largest empirical studies to-date on the impact of design risk management practices on product design success. Through a survey of 224 practices, 38 (in 7 categories) where found to be statistically significant for at least 3 out of 4 performance metrics. The categories are: 1. Organizational Design Experience; 2. Risk Management Personnel and Resources; 3. Tailoring and Integration of Risk Management Process; 4. Risk-Based Decision Making; 5. Specific Mitigation Actions; 6. Monitoring and Review; and 7. Other ISO Risk Management Principles.King Fahd University of Petroleum and Minerals (Center for Clean Water and Clean Energy at MIT and KFUPM (R11-DMN-09))Massachusetts Institute of Technology. Lean Advancement Initiativ

Characteristics and Enablers of Transparency in Product Development Organizations

Risks in product development lead to schedule and cost overruns and poor product quality. While many risk management frameworks have been published and research on specific practices has been conducted, little is understood of key characteristics of successful risk management in product development and how they manifest in real development projects. This research consists of two phases. The first phase is a survey on 171 best practices in risk management. Analysis of over 200 responses from industry practitioners identified transparency as a key characteristic of successful risk management in product development. Due to the limited exploration of the concept of transparency in the literature, the second phase of this work consisted of a qualitative investigation of transparency through interviews with 15 industry practitioners. Analysis of the interview results suggests a hierarchical structure which decomposes transparency into several characteristics and identifies enablers for each of these characteristics. We propose that transparency can be a valuable lever for product developers and managers. Future work is needed to validate the generalizability of the observations provided

Stellar Collisions and the Interior Structure of Blue Stragglers

Collisions of main sequence stars occur frequently in dense star clusters. In open and globular clusters, these collisions produce merger remnants that may be observed as blue stragglers. Detailed theoretical models of this process require lengthy hydrodynamic computations in three dimensions. However, a less computationally expensive approach, which we present here, is to approximate the merger process (including shock heating, hydrodynamic mixing, mass ejection, and angular momentum transfer) with simple algorithms based on conservation laws and a basic qualitative understanding of the hydrodynamics. These algorithms have been fine tuned through comparisons with the results of our previous hydrodynamic simulations. We find that the thermodynamic and chemical composition profiles of our simple models agree very well with those from recent SPH (smoothed particle hydrodynamics) calculations of stellar collisions, and the subsequent stellar evolution of our simple models also matches closely that of the more accurate hydrodynamic models. Our algorithms have been implemented in an easy to use software package, which we are making publicly available (see http://vassun.vassar.edu/~lombardi/mmas/). This software could be used in combination with realistic dynamical simulations of star clusters that must take into account stellar collisions.Comment: This revised version has 37 pages, 13 figures, 4 tables; submitted to ApJ; for associated software package, see http://vassun.vassar.edu/~lombardi/mmas/ This revised version presents additional comparisons with SPH results and slightly improved merger recipe

Young people with diabetes and their peers

Type 1 Diabetes (T1D) is amongst the most common form of chronic illness affecting young people in the UK. Self- management is crucial, but managing their T1D is often difficult for young people

Parallel HOP: A Scalable Halo Finder for Massive Cosmological Data Sets

Modern N-body cosmological simulations contain billions ($10^9$) of dark matter particles. These simulations require hundreds to thousands of gigabytes of memory, and employ hundreds to tens of thousands of processing cores on many compute nodes. In order to study the distribution of dark matter in a cosmological simulation, the dark matter halos must be identified using a halo finder, which establishes the halo membership of every particle in the simulation. The resources required for halo finding are similar to the requirements for the simulation itself. In particular, simulations have become too extensive to use commonly-employed halo finders, such that the computational requirements to identify halos must now be spread across multiple nodes and cores. Here we present a scalable-parallel halo finding method called Parallel HOP for large-scale cosmological simulation data. Based on the halo finder HOP, it utilizes MPI and domain decomposition to distribute the halo finding workload across multiple compute nodes, enabling analysis of much larger datasets than is possible with the strictly serial or previous parallel implementations of HOP. We provide a reference implementation of this method as a part of the toolkit yt, an analysis toolkit for Adaptive Mesh Refinement (AMR) data that includes complementary analysis modules. Additionally, we discuss a suite of benchmarks that demonstrate that this method scales well up to several hundred tasks and datasets in excess of $2000^3$ particles. The Parallel HOP method and our implementation can be readily applied to any kind of N-body simulation data and is therefore widely applicable.Comment: 29 pages, 11 figures, 2 table

Crafting a new materialist care story: Using wet wool felting to explore mattering and caring in early childhood settings

This article presents a methodological account of a postqualitative approach to research investigating entanglements among crafting experiences of wet wool felting and a story of caring in an early childhood education and care (ECEC) setting. The concept of care is understood as central to relationships in ECEC settings. Multiple theorisations shape contours of a conceptual landscape of care. Caring relationships may be envisaged as close, dyadic bonds of nurturing, or as networks of reciprocal relationships among humans, or entangled relations where care happens among humans, non-humans, and materials. From a posthumanist perspective, care stories in early childhood teaching and learning involve much more than human individuals. Early childhood practitioners, children in early childhood settings, their families, teacher educators, and policymakers can benefit from understanding how multiple, diverse components of early childhood settings continually produce care and caring relationships. New materialist theories reconceptualise care where humans, other-than-humans and materialities are constantly produced in intra-actions as temporary outcomes of entangled relations. Bringing materials into view as producing and being produced alongside humans raises possibilities for considering how care matters and how matter cares in early childhood education environments. Playfully, with curiosity, I engage with wet wool felting physically, intellectually, and emotionally. Entangled in crafting processes, I am produced as researcher, as carer and cared-for with materials. Concepts of caring and felting are multifaceted, providing rich contours of meaning. I am enmeshed in sensual experiences of thinking-making-doing, alongside some text from a research study into emotions in early childhood teaching in Aotearoa New Zealand. Contours of concepts of caring and felting are explored through crafting experiences interwoven with writing about care and caring relationships in ECEC settings

Exploring how young people think about and respond to diabetes in their peers

Adolescence is a difficult time for people with diabetes and it is often accompanied by a deterioration in blood glucose control. This article looks at the effect the attitudes of peers can have on adolescents with diabetes. Three focus groups of 12–14-year-olds were asked about their knowledge of diabetes and were then presented with realistic vignettes about the condition, which they discussed. They then took part in a mythbusting session to help address misconceptions. The research team identified themes that emerged from the focus groups. Their findings suggest that a supportive peer network may be a valuable resource in good management of diabetes in young people. The research team suggest that more education about the condition is needed in schools and should be designed in collaboration with young people with diabetes

Short-term genome stability of serial Clostridium difficile ribotype 027 isolates in an experimental gut model and recurrent human disease

Copyright: © 2013 Eyre et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedClostridium difficile whole genome sequencing has the potential to identify related isolates, even among otherwise indistinguishable strains, but interpretation depends on understanding genomic variation within isolates and individuals.Serial isolates from two scenarios were whole genome sequenced. Firstly, 62 isolates from 29 timepoints from three in vitro gut models, inoculated with a NAP1/027 strain. Secondly, 122 isolates from 44 patients (2–8 samples/patient) with mostly recurrent/on-going symptomatic NAP-1/027 C. difficile infection. Reference-based mapping was used to identify single nucleotide variants (SNVs).Across three gut model inductions, two with antibiotic treatment, total 137 days, only two new SNVs became established. Pre-existing minority SNVs became dominant in two models. Several SNVs were detected, only present in the minority of colonies at one/two timepoints. The median (inter-quartile range) [range] time between patients’ first and last samples was 60 (29.5–118.5) [0–561] days. Within-patient C. difficile evolution was 0.45 SNVs/called genome/year (95%CI 0.00–1.28) and within-host diversity was 0.28 SNVs/called genome (0.05–0.53). 26/28 gut model and patient SNVs were non-synonymous, affecting a range of gene targets.The consistency of whole genome sequencing data from gut model C. difficile isolates, and the high stability of genomic sequences in isolates from patients, supports the use of whole genome sequencing in detailed transmission investigations.Peer reviewe