223 research outputs found
Probing the Structure and Energetics of Dislocation Cores in SiGe Alloys through Monte Carlo Simulations
We present a methodology for the investigation of dislocation energetics in
segregated alloys based on Monte Carlo simulations which equilibrate the
topology and composition of the dislocation core and its surroundings. An
environment-dependent partitioning of the system total energy into atomic
contributions allows us to link the atomistic picture to continuum elasticity
theory. The method is applied to extract core energies and radii of 60 degrees
glide dislocations in segregated SiGe alloys which are inaccessible by other
methods.Comment: 5 pages, to be published in Physical Review Letter
An Intervention in literacy in three Pacific nations: Implications of a context specific approach to co-design
In this paper, we consider the implications of a commitment to acknowledging the role of context within a research practice partnership. We outline the approach to doing so within a design-based research intervention with 42 schools across three Pacific Island countries to improve literacy learning and language development. In doing so, the paper identifies context as a central concern for student and teacher learning, for schools as organisations and for intervention implementation. We draw on theories of context from each of these research bases to consider how aid interventions can best contribute to enhancing student learning outcomes across varied student populations in a way that is contextually appropriate, and builds sustainable local capability for ongoing improvement. Â In considering these concerns we argue for the potential of a design-based research approach, based on the Learning Schools Model (McNaughton, Lai, Jesson Wilson, 2013) to incorporate âco-designâ of the intervention. Â We exemplify how the process of jointly designing the content and implementation within preset phases of implementation is possible in ways that draw on the varied expertise of in-country and external partners. The focus on collective knowledge building, collective problem solving and sharing practice within trusting relationships is considered to foster capacity for sustained adaptation and improvement at local levels. We believe such an approach is relevant to the challenges faced by Pacific Island Ministries of Education and their aid donor partners in designing effective interventions for learning improvement
The influence of surface stress on the equilibrium shape of strained quantum dots
The equilibrium shapes of InAs quantum dots (i.e., dislocation-free, strained
islands with sizes >= 10,000 atoms) grown on a GaAs (001) substrate are studied
using a hybrid approach which combines density functional theory (DFT)
calculations of microscopic parameters, surface energies, and surface stresses
with elasticity theory for the long-range strain fields and strain relaxations.
In particular we report DFT calculations of the surface stresses and analyze
the influence of the strain on the surface energies of the various facets of
the quantum dot. The surface stresses have been neglected in previous studies.
Furthermore, the influence of edge energies on the island shapes is briefly
discussed. From the knowledge of the equilibrium shape of these islands, we
address the question whether experimentally observed quantum dots correspond to
thermal equilibrium structures or if they are a result of the growth kinetics.Comment: 7 pages, 8 figures, submitted to Phys. Rev. B (February 2, 1998).
Other related publications can be found at
http://www.rz-berlin.mpg.de/th/paper.htm
The Role of Entrepreneur-Venture Fit in Online Home-based Entrepreneurship: A Systematic Literature Review
Home-based businesses and their founders represent an important, but under-researched facet of entrepreneurship. Far from being small, hobby-businesses with little economic impact, home-based business make significant contribution to national economies in terms of both turnover and employment. Online home-based businesses have been recognised as an important and distinct sector of the home-based business domain, offering unique opportunity for innovation and business diversity. The paper presents a systematic literature review of extant research on online home-based entrepreneurs and their businesses. The findings of the review are structured and discussed using the theoretical lens of entrepreneur-venture fit. Use of this lens allows the study to bring coherence to previously fragmented extant studies, providing a basis for future research in this domain. The study also develops a novel model of entrepreneur-venture fit in the specific case of online home-based businesses. This allows us to suggest five positive interactions between entrepreneurial and venture characteristics. It also allows us to suggest a number of previously unidentified negative interactions, which may result in entrepreneurs becoming âlocked-inâ and suffering multiple sources of stress
Dislocation Free Island Formation in Heteroepitaxial Growth: An Equilibrium Study
We investigate the equilibrium properties of strained heteroepitaxial
systems, incorporating the formation and the growth of a wetting film,
dislocation free island formation, and ripening. The derived phase diagram
provides a detailed characterization of the possible growth modes in terms of
the island density, equilibrium island size, and wetting layer thickness.
Comparing our predictions with experimental results we discuss the growth
conditions that can lead to stable islands as well as ripening.Comment: 4 pages, LaTeX, 3 ps figure
Equilibrium shapes and energies of coherent strained InP islands
The equilibrium shapes and energies of coherent strained InP islands grown on
GaP have been investigated with a hybrid approach that has been previously
applied to InAs islands on GaAs. This combines calculations of the surface
energies by density functional theory and the bulk deformation energies by
continuum elasticity theory. The calculated equilibrium shapes for different
chemical environments exhibit the {101}, {111}, {\=1\=1\=1} facets and a (001)
top surface. They compare quite well with recent atomic-force microscopy data.
Thus in the InP/GaInP-system a considerable equilibration of the individual
islands with respect to their shapes can be achieved. We discuss the
implications of our results for the Ostwald ripening of the coherent InP
islands. In addition we compare strain fields in uncapped and capped islands.Comment: 10 pages including 6 figures. Submitted to Phys. Rev. B. Related
publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm
Pharmacists in Pharmacovigilance: Can Increased Diagnostic Opportunity in Community Settings Translate to Better Vigilance?
The pharmacy profession has undergone substantial change over the last two to three decades. Whilst medicine supply still remains a central function, pharmacistâs roles and responsibilities have become more clinic and patient focused. In the community (primary care), pharmacists have become important providers of healthcare as Western healthcare policy advocates patient self-care. This has resulted in pharmacists taking on greater responsibility in managing minor illness and the delivery of public health interventions. These roles require pharmacists to more fully use their clinical skills, and often involve diagnosis and therapeutic management. Community pharmacists are now, more than ever before, in a position to identify, record and report medication safety incidents. However, current research suggests that diagnostic ability of community pharmacists is questionable and they infrequently report to local or national schemes. The aim of this paper is to highlight current practice and suggest ways in which community pharmacy can more fully contribute to patient safety
LAMP: Large Deep Nets with Automated Model Parallelism for Image Segmentation
Deep Learning (DL) models are becoming larger, because the increase in model
size might offer significant accuracy gain. To enable the training of large
deep networks, data parallelism and model parallelism are two well-known
approaches for parallel training. However, data parallelism does not help
reduce memory footprint per device. In this work, we introduce Large deep 3D
ConvNets with Automated Model Parallelism (LAMP) and investigate the impact of
both input's and deep 3D ConvNets' size on segmentation accuracy. Through
automated model parallelism, it is feasible to train large deep 3D ConvNets
with a large input patch, even the whole image. Extensive experiments
demonstrate that, facilitated by the automated model parallelism, the
segmentation accuracy can be improved through increasing model size and input
context size, and large input yields significant inference speedup compared
with sliding window of small patches in the inference. Code is
available\footnote{https://monai.io/research/lamp-automated-model-parallelism}.Comment: MICCAI 2020 Early Accepted paper. Code is
available\footnote{https://monai.io/research/lamp-automated-model-parallelism
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Care homesâ use of medicines study: prevalence, causes and potential harm of medication errors in care homes for older people
Introduction: Care home residents are at particular risk from medication errors, and our objective was to determine the prevalence and potential harm of prescribing, monitoring, dispensing and administration errors in UK care homes, and to identify their causes.
Methods: A prospective study of a random sample of residents within a purposive sample of homes in three areas. Errors were identified by patient interview, note review, observation of practice and examination of dispensed items. Causes were understood by observation and from theoretically framed interviews with home staff, doctors and pharmacists. Potential harm from errors was assessed by expert judgement.
Results: The 256 residents recruited in 55 homes were taking a mean of 8.0 medicines. One hundred and seventy-eight (69.5%) of residents had one or more errors. The mean number per resident was 1.9 errors. The mean potential harm from prescribing, monitoring, administration and dispensing errors was 2.6, 3.7, 2.1 and 2.0 (0â=âno harm, 10â=âdeath), respectively. Contributing factors from the 89 interviews included doctors who were not accessible, did not know the residents and lacked information in homes when prescribing; home staffâs high workload, lack of medicines training and drug round interruptions; lack of team work among home, practice and pharmacy; inefficient ordering systems; inaccurate medicine records and prevalence of verbal communication; and difficult to fill (and check) medication administration systems.
Conclusions: That two thirds of residents were exposed to one or more medication errors is of concern. The will to improve exists, but there is a lack of overall responsibility. Action is required from all concerned
2 x 2 Polyethylene Reflected and Moderated Highly Enriched Uranium System with Rhenium
The 2 Ă 2 array HEU-Re experiment was performed on the Planet universal critical assembly machine on November 4th, 2003 at the Los Alamos Critical Experiments Facility (LACEF) at Los Alamos National Laboratory (LANL). For this experiment, there were 10 Âœ units, each full unit containing four HEU foils and two rhenium foils. The top unit contained only two HEU foils and two rhenium foils. A total of 42 HEU foils were used for this experiment. Rhenium is a desirable cladding material for space nuclear power applications. This experiment consisted of HEU foils interleaved with rhenium foils and is moderated and reflected by polyethylene plates. A unit consisted of a polyethylene plate, which has a recess for rhenium foils, and four HEU foils in a single layer in the top recess of each polyethylene plate. The Planet universal criticality assembly machine has been previously used in experiments containing HEU foils interspersed with SiO2 (HEU-MET-THERM-001), Al (HEU-MET-THERM-008), MgO (HEU-MET-THERM-009), Gd foils (HEU-MET-THERM-010), 2 Ă 2 Ă 26 Al (HEU-MET-THERM-012), Fe (HEU-MET-THERM-013 and HEU-MET-THERM-015), 2 Ă 2 Ă 23 SiO2 (HEU-MET-THERM-014), 2 Ă 2 Ă 11 hastalloy plates (HEU-MET-THERM-016), and concrete (HEU-MET-THERM-018). The 2 Ă 2 array of HEU-Re is considered acceptable for use as a benchmark critical experiment
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