Temperature dependence of the band gap shrinkage due to electron-phonon interaction in undoped n-type GaN

The photoluminescence spectra of band-edge transitions in GaN is studied as a function of temperature. The parameters that describe the temperature dependence red-shift of the band-edge transition energy and the broadening of emission line are evaluated using different models. We find that the semi-empirical relation based on phonon-dispersion related spectral function leads to excellent fit to the experimental data. The exciton-phonon coupling constants are determined from the analysis of linewidth broadening

Design and Implementation of a Remote Care Application Based on Microservice Architecture

Microservice Architecture (MSA) is an architectural style for service-based software systems. MSA puts a strong emphasis on high cohesion and loose coupling of the services that provide systems' functionalities. As a result of this, MSA-based software architectures exhibit increased scalability and extensibility, and facilitate the application of continuous integration techniques. This paper presents a case study of an MSA-based Remote Care Application (RCA) that allows caregivers to remotely access smart home devices. The goal of the RCA is to assist persons being cared in Activities of Daily Living. Employing MSA for the realization of the RCA yielded several lessons learned, e.g., (i) direct transferability of domain models based on Domain-driven Design; (ii) more efficient integration of features; (iii) speedup of feature delivery due to MSA facilitating automated deployment.Comment: 8 pages, 3 figures, 2 table

Continuous Percolation Phase Transitions of Two-dimensional Lattice Networks under a Generalized Achlioptas Process

The percolation phase transitions of two-dimensional lattice networks under a generalized Achlioptas process (GAP) are investigated. During the GAP, two edges are chosen randomly from the lattice and the edge with minimum product of the two connecting cluster sizes is taken as the next occupied bond with a probability $p$. At $p=0.5$, the GAP becomes the random growth model and leads to the minority product rule at $p=1$. Using the finite-size scaling analysis, we find that the percolation phase transitions of these systems with $0.5 \le p \le 1$ are always continuous and their critical exponents depend on $p$. Therefore, the universality class of the critical phenomena in two-dimensional lattice networks under the GAP is related to the probability parameter $p$ in addition.Comment: 7 pages, 14 figures, accepted for publication in Eur. Phys. J.

School Instructional Program Coherence: Benefits and Challenges

This report is one of a series of special topic reports developed by the Chicago Annenberg Research Project. It discusses an important reason why schools involved in multiple improvement initiatives do not always improve their students' achievements. It introduces the concept of instructional program coherence and presents new evidence that students in Chicago elementary schools with stronger program coherence show higher gains in student achievement. The report suggests ways in which school leaders, school improvement partners, and policy makers can act to bring about the instructional coherence that will reward their school improvement efforts

A cross‐faculty simulation model for authentic learning

This paper proposes a cross‐faculty simulation model for authentic learning that bridges the gap between short group‐based simulations within the classroom and longer individual placements in professional working contexts. Dissemination of the model is expected to widen the use of authentic learning approaches in higher education (HE). The model is based on a cross‐faculty project in which UK HE students acted as professional developers to produce prototype educational games for academic clients from other subject areas. Perceptions about the project were obtained from interviews with project participants. The stakeholders believed the cross‐faculty simulation to be a motivating learning experience, whilst identifying possible improvements. To evaluate whether the authenticity of the student–client relationship could be improved, the interview data were compared to four themes for authentic learning described by Rule in 2006. The data supported Rule’s themes, whilst highlighting the added value gained from meta‐awareness of the simulation as a learning opportunity

Properties of a random attachment growing network

In this study we introduce and analyze the statistical structural properties of a model of growing networks which may be relevant to social networks. At each step a new node is added which selects 'k' possible partners from the existing network and joins them with probability delta by undirected edges. The 'activity' of the node ends here; it will get new partners only if it is selected by a newcomer. The model produces an infinite-order phase transition when a giant component appears at a specific value of delta, which depends on k. The average component size is discontinuous at the transition. In contrast, the network behaves significantly different for k=1. There is no giant component formed for any delta and thus in this sense there is no phase transition. However, the average component size diverges for delta greater or equal than one half.Comment: LaTeX, 19 pages, 6 figures. Discussion section, comments, a new figure and a new reference are added. Equations simplifie

Lyapunov exponents and transport in the Zhang model of Self-Organized Criticality

We discuss the role played by the Lyapunov exponents in the dynamics of Zhang's model of Self-Organized Criticality. We show that a large part of the spectrum (slowest modes) is associated with the energy transpor in the lattice. In particular, we give bounds on the first negative Lyapunov exponent in terms of the energy flux dissipated at the boundaries per unit of time. We then establish an explicit formula for the transport modes that appear as diffusion modes in a landscape where the metric is given by the density of active sites. We use a finite size scaling ansatz for the Lyapunov spectrum and relate the scaling exponent to the scaling of quantities like avalanche size, duration, density of active sites, etc ...Comment: 33 pages, 6 figures, 1 table (to appear