The Novel Coronavirus Outbreak: a Challenge Beyond Borders

Coronaviruses infect mammals and birds worldwide, and some of these viruses infect humans to cause mild to moderate lower-respiratory tract illnesses and rarely a severe illness. Like other viruses, coronaviruses evolved (change their genetic material and protein structure) and spread from animals to humans. The world has witnessed coronavirus evolving into severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 and the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012. Other recent examples include Dengue, Ebola, Chikungunya, Influenza and Zika virus outbreaks. It may or may not be relevant to note that first cases of both SARS-CoV in 2003 avian influenza virus (H5N1) in 1997 were isolated and identified at the same hospital in Hong Kong where the first case of the current outbreak of the Wuhan coronavirus has been identified. The new virus has been named as the Novel coronavirus (2019 nCoV)

Integrals of monomials over the orthogonal group

A recursion formula is derived which allows to evaluate invariant integrals over the orthogonal group O(N), where the integrand is an arbitrary finite monomial in the matrix elements of the group. The value of such an integral is expressible as a finite sum of partial fractions in $N$. The recursion formula largely extends presently available integration formulas for the orthogonal group.Comment: 9 pages, no figure

Footsteps in the fog: Certificateless fog-based access control

The proliferating adoption of the Internet of Things (IoT) paradigm has fuelled the need for more efficient and resilient access control solutions that aim to prevent unauthorized resource access. The majority of existing works in this field follow either a centralized approach (i.e. cloud-based) or an architecture where the IoT devices are responsible for all decision-making functions. Furthermore, the resource-constrained nature of most IoT devices make securing the communication between these devices and the cloud using standard cryptographic solutions difficult. In this paper, we propose a distributed access control architecture where the core components are distributed between fog nodes and the cloud. To facilitate secure communication, our architecture utilizes a Certificateless Hybrid Signcryption scheme without pairing. We prove the effectiveness of our approach by providing a comparative analysis of its performance in comparison to the commonly used cloud-based centralized architectures. Our implementation uses Azure – an existing commercial platform, and Keycloak – an open-source platform, to demonstrate the real-world applicability. Additionally, we measure the performance of the adopted encryption scheme on two types of resource-constrained devices to further emphasize the applicability of the proposed architecture. Finally, the experimental results are coupled with a theoretical analysis that proves the security of our approach

A review of recent analytical and experimental studies applicable to LMFBR fuel and blanket assembly design / by E. Khan and N. Todreas

"September, 1973."Includes bibliographical references (pages [40]-[44])U.S. Atomic Energy Commission contract AT(11-1)-224

Heavy ion ranges from first-principles electron dynamics

The effects of incident energetic particles, and the modification of materials under irradiation, are governed by the mechanisms of energy losses of ions in matter. The complex processes affecting projectiles spanning many orders of magnitude in energy depend on both ion and electron interactions. Developing multi-scale modeling methods that correctly capture the relevant processes is crucial for predicting radiation effects in diverse conditions. In this work, we obtain channeling ion ranges for tungsten, a prototypical heavy ion, by explicitly simulating ion trajectories with a method that takes into account both the nuclear and the electronic stopping power. The electronic stopping power of self-ion irradiated tungsten is obtained from first-principles time-dependent density functional theory (TDDFT). Although the TDDFT calculations predict a lower stopping power than SRIM by a factor of three, our result shows very good agreement in a direct comparison with ion range experiments. These results demonstrate the validity of the TDDFT method for determining electronic energy losses of heavy projectiles, and in turn its viability for the study of radiation damage.Peer reviewe

Simplification of Reversible Markov Chains by Removal of States With Low Equilibrium Occupancy

We present a practical method for simplifying Markov chains on a potentially large state space when detailed balance holds. A simple and transparent technique is introduced to remove states with low equilibrium occupancy. The resulting system has fewer parameters. The resulting effective rates between the remaining nodes give dynamics identical to the original system’s except on very fast timescales. This procedure amounts to using separation of timescales to neglect small capacitance nodes in a network of resistors and capacitors. We illustrate the technique by simplifying various reaction networks, including transforming an acyclic four-node network to a three-node cyclic network. For a reaction step in which a ligand binds, the law of mass action implies a forward rate proportional to ligand concentration. The effective rates in the simplified network are found to be rational functions of ligand concentratio

Three-dimensional FE-EFGM adaptive coupling with application to nonlinear adaptive analysis

Three-dimensional problems with both material and geometrical nonlinearities are of practical importance in many engineering applications, e.g. geomechanics, metal forming and biomechanics. Traditionally, these problems are simulated using an adaptive finite element method (FEM). However, the FEM faces many challenges in modeling these problems, such as mesh distortion and selection of a robust refinement algorithm. Adaptive meshless methods are a more recent technique for modeling these problems and can overcome the inherent mesh based drawbacks of the FEM but are computationally expensive. To take advantage of the good features of both methods, in the method proposed in this paper, initially the whole of the problem domain is modeled using the FEM. During an analysis those elements which violate a predefined error measure are automatically converted to a meshless zone. This zone can be further refined by adding nodes, overcoming computationally expensive FE remeshing. Therefore an appropriate coupling between the FE and the meshless zone is vital for the proposed formulation. One of the most widely used meshless methods, the element-free Galerkin method (EFGM), is used in this research. Maximum entropy shape functions are used instead of the conventional moving least squares based formulations'. These shape functions posses a weak Kronecker delta property at the boundaries of the problem domain, which allows the essential boundary conditions to be imposed directly and also helps to avoid the use of a transition region in the coupling between the FE and the EFG regions. Total Lagrangian formulation is preferred over the updated Lagrangian formulation for modeling finite deformation due to its computational efficiency. The well-established error estimation procedure of Zienkiewicz-Zhu is used in the FE region to determine the elements requiring conversion to the EFGM. The Chung and Belytschko error estimator is used in the EFG region for further adaptive refinement. Numerical examples are presented to demonstrate the performance of the current approach in thre