Diagonalization of a bosonic quadratic form using CCM: Application on a system with two interpenetrating square lattice antiferromagnets

While the diagonalization of a quadratic bosonic form can always be done using a Bogoliubov transformation, the practical implementation for systems with a large number of different bosons is a tedious analytical task. Here we use the coupled cluster method (CCM) to exactly diagonalise such complicated quadratic forms. This yields to a straightforward algorithm which can easily be implemented using computer algebra even for a large number of different bosons. We apply this method on a Heisenberg system with two interpenetrating square lattice antiferromagnets, which is a model for the quasi 2D antiferromagnet Ba_2Cu_3O_4Cl_2. Using a four-magnon spin wave approximation we get a complicated Hamiltonian with four different bosons, which is treated with CCM. Results are presented for magnetic ground state correlations.Comment: 4 pages, 2 Postscript figures, to be published in acta physica polonica A (European Conference 'Physics of Magnetism 99'

Putting Computerized Instruction to the Test: A Randomized Evaluation of a "Scientifically-based" Reading Program

Although schools across the country are investing heavily in computers in the classroom, there is surprisingly little evidence that they actually improve student achievement. In this paper we present results from a randomized study of a well-defined use of computers in schools: a popular instructional computer program, known as Fast ForWord, which is designed to improve language and reading skills. We assess the impact of the program using four different measures of language and reading ability. Our estimates suggest that while use of the computer program may improve some aspects of students' language skills, it does not appear that these gains translate into a broader measure of language acquisition or into actual reading skills.

Planting the Seeds for Public Health: How the Farm Bill Can Help Farmers to Produce and Distribute Healthy Foods

Analyzes provisions in the 2008 Farm Bill that impede farmers' production and strategic marketing of fruits and vegetables. Recommends policy changes to remove such barriers, improve consumer access to healthy foods, and help prevent childhood obesity

Coupled Cluster Treatment of the XY model

We study quantum spin systems in the 1D, 2D square and 3D cubic lattices with nearest-neighbour XY exchange. We use the coupled-cluster method (CCM) to calculate the ground-state energy, the T=0 sublattice magnetisation and the excited state energies, all as functions of the anisotropy parameter $\gamma$. We consider $S=1/2$ in detail and give some results for higher $S$. In 1D these results are compared with the exact $S=1/2$ results and in 2D with Monte-Carlo and series expansions. We obtain critical points close to the expected value $\gamma=0$ and our extrapolated LSUBn results for the ground-state energy are well converged for all $\gamma$ except very close to the critical point.Comment: 11 pages, Latex, 4 postscript figure, accepted by J.Phys.: Condens. Matte

Acid catalyzed reactions of alpha and beta styryl azides

Acid degradation of alpha and beta styryl azide

The formation of 3,6-diphenylpyridazine and 2,5-diphenylpyrrole from alpha-styryl azide

Formation of 3,6-diphenylpyridazine and 2,5- diphenylpyrrole from alpha-styryl azid

Search for the Cause of Vaping Associated Lung Injury in Adolescents

In August 2019 an unexplained, exponential rise in severe respiratory illnesses in previously healthy young adults, swept across America catching the attention of medical providers. Hospital admissions for lung injury increased 10-fold over two months’ time leaving practitioners scrambling for answers. All affected patients were found to have used e-cigarettes prior to symptoms and endorsed using nicotine and marijuana vape pens. The medical community quickly began to search for the cause of these vaping associated lung injuries. Understanding the mechanism of injury is important in order to assist in educating the public about the risks associated with e-cigarettes. The aim of this paper is to present the research, or lack thereof, surrounding the risks of electronic cigarettes and their association with severe lung injury. A thorough literature review was performed eliciting 12 appropriate studies. A conclusive causative agent for EVALI has not been identified but several possible culprits are Vitamin E Acetate, propylene glycol or glycerol and metal nanoparticles. Recommendations for future research, provider and patient education and policy change are provided