Optical Properties of Wide Band Gap Indium Sulphide Thin Films Obtained by Physical Vapor Deposition

Thin films of indium sulphide containing oxygen have been synthesized following a dry physical process. The constituents are deposited by thermal evaporation on glass substrates and then annealed under argon flow. Polycrystalline β-In2S3 containing oxygen thin films are obtained as soon as the temperature of annealing is between 623 and 723 K. In this paper, these β-In2S3 thin films have optically been studied. The optical band gap is direct. Its value is not dependent on the temperature of annealing. It is about 2.8 eV, which is higher than that of β-In2S3 single crystal. This high value is related to the presence of oxygen in the films. The extinction coefficient k and the refractive index n of the films have also been found independent of the annealing temperature. These optical properties make the films studied good candidates to be substituted to CdS in Cu(In,Ga)Se2 based solar cells

Stumbling Blocks of Online Learning During COVID 19 Pandemic – Perspectives of Students of Selected Universities in London

COVID 19 Pandemic has led to mayhem across the Planet. Educational institutions are the worst affected arena. There is a paradigm shift from conventional classroom teaching to online methods. But it has its own obstructions. Thus, this research is undertaken to study the impediments of online learning faced by the students of selected universities of London. The questionnaire was administered among 200 students out of which 196 responded. The results of the Study reveal that the major obstructions which hindered online learning were lack of computer skills, internet connectivity issues, difficulty in operating the software, absence of social bonding between teachers and students, difficulty in recording lectures, difficulty in grasping practical courses such as mathematics, finance, accounting, engineering etc. To cope up with the Stumbling Blocks, the Study advocates some of the most innovative and creative ways such as application of Bloom’s Digital Taxonomy, VARK Model, 5/5/5 rule etc

Reduced basis isogeometric mortar approximations for eigenvalue problems in vibroacoustics

We simulate the vibration of a violin bridge in a multi-query context using reduced basis techniques. The mathematical model is based on an eigenvalue problem for the orthotropic linear elasticity equation. In addition to the nine material parameters, a geometrical thickness parameter is considered. This parameter enters as a 10th material parameter into the system by a mapping onto a parameter independent reference domain. The detailed simulation is carried out by isogeometric mortar methods. Weakly coupled patch-wise tensorial structured isogeometric elements are of special interest for complex geometries with piecewise smooth but curvilinear boundaries. To obtain locality in the detailed system, we use the saddle point approach and do not apply static condensation techniques. However within the reduced basis context, it is natural to eliminate the Lagrange multiplier and formulate a reduced eigenvalue problem for a symmetric positive definite matrix. The selection of the snapshots is controlled by a multi-query greedy strategy taking into account an error indicator allowing for multiple eigenvalues

ITERATED QUASI-REVERSIBILITY METHOD APPLIED TO ELLIPTIC AND PARABOLIC DATA COMPLETION PROBLEMS

International audienceWe study the iterated quasi-reversibility method to regularize ill-posed elliptic and parabolic problems: data completion problems for Poisson's and heat equations. We define an abstract setting to treat both equations at once. We demonstrate the convergence of the regularized solution to the exact one, and propose a strategy to deal with noise on the data. We present numerical experiments for both problems: a two-dimensional corrosion detection problem and the one-dimensional heat equation with lateral data. In both cases, the method prove to be efficient even with highly corrupted data

Light induced self-written waveguides interactions in photopolymer media

We present experimental and theoretical study of the interaction of Light Induced Self-Written (LISW) waveguides in photopolymers. We show that the diffusion of the monomer controls the refractive index distribution. Consequently it influences the interaction between the LISW channels allowing the observation of anti-crossing behavior or the propagation of an array of non interacting LISW waveguides

Weakly Consistent Regularisation Methods for Ill-Posed Problems

This Chapter takes its origin in the lecture notes for a 9 h course at the Institut Henri Poincaré in September 2016. The course was divided in three parts. In the first part, which is not included herein, the aim was to first recall some basic aspects of stabilised finite element methods for convection-diffusion problems. We focus entirely on the second and third parts which were dedicated to ill-posed problems and their approximation using stabilised finite element methods. First we introduce the concept of conditional stability. Then we consider the elliptic Cauchy-problem and a data assimilation problem in a unified setting and show how stabilised finite element methods may be used to derive error estimates that are consistent with the stability properties of the problem and the approximation properties of the finite element space. Finally, we extend the result to a data assimilation problem subject to the heat equation

Gustatory Perception and Fat Body Energy Metabolism Are Jointly Affected by Vitellogenin and Juvenile Hormone in Honey Bees

Honey bees (Apis mellifera) provide a system for studying social and food-related behavior. A caste of workers performs age-related tasks: young bees (nurses) usually feed the brood and other adult bees inside the nest, while older bees (foragers) forage outside for pollen, a protein/lipid source, or nectar, a carbohydrate source. The workers' transition from nursing to foraging and their foraging preferences correlate with differences in gustatory perception, metabolic gene expression, and endocrine physiology including the endocrine factors vitellogenin (Vg) and juvenile hormone (JH). However, the understanding of connections among social behavior, energy metabolism, and endocrine factors is incomplete. We used RNA interference (RNAi) to perturb the gene network of Vg and JH to learn more about these connections through effects on gustation, gene transcripts, and physiology. The RNAi perturbation was achieved by single and double knockdown of the genes ultraspiracle (usp) and vg, which encode a putative JH receptor and Vg, respectively. The double knockdown enhanced gustatory perception and elevated hemolymph glucose, trehalose, and JH. We also observed transcriptional responses in insulin like peptide 1 (ilp1), the adipokinetic hormone receptor (AKHR), and cGMP-dependent protein kinase (PKG, or “foraging gene” Amfor). Our study demonstrates that the Vg–JH regulatory module controls changes in carbohydrate metabolism, but not lipid metabolism, when worker bees shift from nursing to foraging. The module is also placed upstream of ilp1, AKHR, and PKG for the first time. As insulin, adipokinetic hormone (AKH), and PKG pathways influence metabolism and gustation in many animals, we propose that honey bees have conserved pathways in carbohydrate metabolism and conserved connections between energy metabolism and gustatory perception. Thus, perhaps the bee can make general contributions to the understanding of food-related behavior and metabolic disorders

Cosmology with the Laser Interferometer Space Antenna

The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational wave observations by LISA to probe the universe