3,691 research outputs found
Theory for the electromigration wind force in dilute alloys
A multiple scattering formulation for the electromigration wind force on
atoms in dilute alloys is developed. The theory describes electromigration via
a vacancy mechanism. The method is used to calculate the wind valence for
electromigration in various host metals having a close-packed lattice
structure, namely aluminum, the noble metals copper, silver and gold and the
transition metals. The self-electromigration results for aluminum and the
noble metals compare well with experimental data. For the metals small
wind valences are found, which make these metals attractive candidates for the
experimental study of the direct valence.Comment: 18 pages LaTeX, epsfig, 8 figures. to appear in Phys. Rev. B 56 of
15/11/199
Keldysh Green's function approach to coherence in a non-equilibrium steady state: connecting Bose-Einstein condensation and lasing
Solid state quantum condensates often differ from previous examples of
condensates (such as Helium, ultra-cold atomic gases, and superconductors) in
that the quasiparticles condensing have relatively short lifetimes, and so as
for lasers, external pumping is required to maintain a steady state. On the
other hand, compared to lasers, the quasiparticles are generally more strongly
interacting, and therefore better able to thermalise. This leads to questions
of how to describe such non-equilibrium condensates, and their relation to
equilibrium condensates and lasers. This chapter discusses in detail how the
non-equilibrium Green's function approach can be applied to the description of
such a non-equilibrium condensate, in particular, a system of microcavity
polaritons, driven out of equilibrium by coupling to multiple baths. By
considering the steady states, and fluctuations about them, it is possible to
provide a description that relates both to equilibrium condensation and to
lasing, while at the same time, making clear the differences from simple
lasers
Effects of salinity and alkalinity on growth and survival of all-male giant freshwater prawn (Macrobrachium rosenbergii De Man, 1879) juveniles
All-male giant freshwater prawns (AMGFPs) have been a popular crop cultivated in the Mekong Delta, Vietnam, due to their proven production efficiency compared to all-female or mixed-sex prawn cultures. However, the crucial water quality factors impacting AMGFP aquaculture efficiency have yet to be elaborately investigated. Two separate experiments were randomly arranged with three replicates to evaluate the effects of salinity or alkalinity on the growth and survival of AMGFP juveniles during the grow-out period. The results show that the prawn survival rate in the salinity range of 0â15â° varied from 66.1 to 74.8ïŒ
and in a salinity range of 0â5â° was relatively low compared to the range of 10-15â°; however, the difference was not significant among salinities after 90 days of culture (p > 0.05). All the prawn growth performance parameters significantly decreased with increasing salinities of 0, 5, 10, and 15â° after 30, 60, and 90 days of culture (p 0.05), and both were significantly higher than those at salinities of 10 and 15â° (p < 0.05) after 90 days of culture. In addition, the survival rate reached 82.5â84.4ïŒ
and did not significantly differ among alkalinities of 80, 100, 120, 140, and 160 mgCaCO3 Lâ1. However, the growth performance parameters and yield of AMGFPs at an alkalinity of 160 mg Lâ1 were significantly higher than those at lower alkalinities (80, 100, 120, and 140 mg CaCO3 Lâ1) after 90 days of culture. Therefore, it is recommended that a salinity range of 0â5â° and alkalinity of 160 mgCaCO3 Lâ1 is optimal for the growth-out culture of AMGFP juveniles
Time Series Modelling with MATLAB: the SSpace toolbox
SSpace is a MATLAB toolbox for State-Space modeling that provides the user with tools for linear Gaussian, nonlinear, and non-Gaussian systems with the most advanced and up-to-date features available in any State-Space framework. Great flexibility is achieved because each model is coded on a standard MATLAB function, thence having absolute control on particular parameterizations, parameter constraints, time variation of parameters or variances, arbitrary nonlinear relations with inputs, time aggregation, nested models, system concatenation, etc. The toolbox may be used by specifying State-Space systems from scratch or by using ready-to-use templates for standard methods (like VARMAX, exponential smoothing, unobserved components, Dynamic Linear Regression, etc.). The toolbox is freely available via a public code repository with full documentation and help system. This chapter demonstrates the toolboxâs potential with several examples
The electronic structure of amorphous silica: A numerical study
We present a computational study of the electronic properties of amorphous
SiO2. The ionic configurations used are the ones generated by an earlier
molecular dynamics simulations in which the system was cooled with different
cooling rates from the liquid state to a glass, thus giving access to
glass-like configurations with different degrees of disorder [Phys. Rev. B 54,
15808 (1996)]. The electronic structure is described by a tight-binding
Hamiltonian. We study the influence of the degree of disorder on the density of
states, the localization properties, the optical absorption, the nature of
defects within the mobility gap, and on the fluctuations of the Madelung
potential, where the disorder manifests itself most prominently. The
experimentally observed mismatch between a photoconductivity threshold of 9 eV
and the onset of the optical absorption around 7 eV is interpreted by the
picture of eigenstates localized by potential energy fluctuations in a mobility
gap of approximately 9 eV and a density of states that exhibits valence and
conduction band tails which are, even in the absence of defects, deeply located
within the former band gap.Comment: 21 pages of Latex, 5 eps figure
Instructional Strategies to Enhance Dermoscopic Image Interpretation Education: a Review of the Literature
Introduction: In image interpretation education, many educators have shifted away from traditional methods that involve passive instruction and fragmented learning to interactive ones that promote active engagement and integrated knowledge. By training pattern recognition skills in an effective manner, these interactive approaches provide a promising direction for dermoscopy education.
Objectives: A narrative review of the literature was performed to probe emerging directions in medical image interpretation education that may support dermoscopy education. This article represents the second of a two-part review series.
Methods: To promote innovation in dermoscopy education, the International Skin Imaging Collaboration (ISIC) assembled an Education Working Group that comprises international dermoscopy experts and educational scientists. Based on a preliminary literature review and their experiences as educators, the group developed and refined a list of innovative approaches through multiple rounds of discussion and feedback. For each approach, literature searches were performed for relevant articles.
Results: Through a consensus-based approach, the group identified a number of theory-based approaches, as discussed in the first part of this series. The group also acknowledged the role of motivation, metacognition, and early failures in optimizing the learning process. Other promising teaching tools included gamification, social media, and perceptual and adaptive learning modules (PALMs).
Conclusions: Over the years, many dermoscopy educators may have intuitively adopted these instructional strategies in response to learner feedback, personal observations, and changes in the learning environment. For dermoscopy training, PALMs may be especially valuable in that they provide immediate feedback and adapt the training schedule to the individualâs performance
Theory-Based Approaches to Support Dermoscopic Image Interpretation Education: A Review of the Literature
Introduction: Efficient interpretation of dermoscopic images relies on pattern recognition, and the development of expert-level proficiency typically requires extensive training and years of practice. While traditional methods of transferring knowledge have proven effective, technological advances may significantly improve upon these strategies and better equip dermoscopy learners with the pattern recognition skills required for real-world practice.
Objectives: A narrative review of the literature was performed to explore emerging directions in medical image interpretation education that may enhance dermoscopy education. This article represents the first of a two-part review series on this topic.
Methods: To promote innovation in dermoscopy education, the International Skin Imaging Collaboration (ISIC)assembled a 12-member Education Working Group that comprises international dermoscopy experts and educational scientists. Based on a preliminary literature review and their experiences as educators, the group developed and refined a list of innovative approaches through multiple rounds of discussion and feedback. For each approach, literature searches were performed for relevant articles.
Results: Through a consensus-based approach, the group identified a number of emerging directions in image interpretation education. The following theory-based approaches will be discussed in this first part: whole-task learning, microlearning, perceptual learning, and adaptive learning.
Conclusions: Compared to traditional methods, these theory-based approaches may enhance dermoscopy education by making learning more engaging and interactive and reducing the amount of time required to develop expert-level pattern recognition skills. Further exploration is needed to determine how these approaches can be seamlessly and successfully integrated to optimize dermoscopy education
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