Theory and implementation of H\mathcal{H}-matrix based iterative and direct solvers for Helmholtz and elastodynamic oscillatory kernels

In this work, we study the accuracy and efficiency of hierarchical matrix ($\mathcal{H}$-matrix) based fast methods for solving dense linear systems arising from the discretization of the 3D elastodynamic Green's tensors. It is well known in the literature that standard $\mathcal{H}$-matrix based methods, although very efficient tools for asymptotically smooth kernels, are not optimal for oscillatory kernels. $\mathcal{H}^2$-matrix and directional approaches have been proposed to overcome this problem. However the implementation of such methods is much more involved than the standard $\mathcal{H}$-matrix representation. The central questions we address are twofold. (i) What is the frequency-range in which the $\mathcal{H}$-matrix format is an efficient representation for 3D elastodynamic problems? (ii) What can be expected of such an approach to model problems in mechanical engineering? We show that even though the method is not optimal (in the sense that more involved representations can lead to faster algorithms) an efficient solver can be easily developed. The capabilities of the method are illustrated on numerical examples using the Boundary Element Method

RAG-1 Mutations Associated with B-Cell-Negative SCID Dissociate the Nicking and Transesterification Steps of V(D)J Recombination

Some patients with B-cell-negative severe combined immune deficiency (SCID) carry mutations in RAG-1 or RAG-2 that impair V(D)J recombination. Two recessive RAG-1 mutations responsible for B-cell-negative SCID, R621H and E719K, impair V(D)J recombination without affecting formation of single-site recombination signal sequence complexes, specific DNA contacts, or perturbation of DNA structure at the heptamer-coding junction. The E719K mutation impairs DNA cleavage by the RAG complex, with a greater effect on nicking than on transesterification; a conservative glutamine substitution exhibits a similar effect. When cysteine is substituted for E719, RAG-1 activity is enhanced in Mn2+ but remains impaired in Mg2+, suggesting an interaction between this residue and an essential metal ion. The R621H mutation partially impairs nicking, with little effect on transesterification. The residual nicking activity of the R621H mutant is reduced at least 10-fold upon a change from pH 7.0 to pH 8.4. Site-specific nicking is severely impaired by an alanine substitution at R621 but is spared by substitution with lysine. These observations are consistent with involvement of a positively charged residue at position 621 in the nicking step of the RAG-mediated cleavage reaction. Our data provide a mechanistic explanation for one form of hereditary SCID. Moreover, while RAG-1 is directly involved in catalysis of both nicking and transesterification, our observations indicate that these two steps have distinct catalytic requirements

Financial Restrictions, Personal Income Tax (PIT) and Demand for a Permanent Home in a Dynamic Model. An analysis with Panel Data for Spain

This paper analyzes the way in which income tax and liquidity determine the purchase or rental of a permanent home in Spain. To do this, we have developed a theoretical dynamic model based on Euler’s equation. This model is verified using a sample from the 1991-1995 Panel of income taxpayers. Results suggest that the degree of financial restriction is the most relevant variable when determining the possibility of purchasing a home, while tax incentives increase their relative weighting once this asset has been acquired. Incentives for renting a home are relatively insignificant particularly for taxpayers who habitually rent their homes.personal income tax, liquidity, permanent home, tax incentives

Financial Restrictions, Personal Income Tax (PIT) and Demand for a Permanent Home in a Dynamic Model. An analysis with Panel Data for Spain

This paper analyzes the way in which income tax and liquidity determine the purchase or rental of a permanent home in Spain. To do this, we have developed a theoretical dynamic model based on Euler’s equation. This model is verified using a sample from the 1991-1995 Panel of income taxpayers. Results suggest that the degree of financial restriction is the most relevant variable when determining the possibility of purchasing a home, while tax incentives increase their relative weighting once this asset has been acquired. Incentives for renting a home are relatively insignificant particularly for taxpayers who habitually rent their homes.personal income tax, liquidity, permanent home, tax incentives

Lymphopoiesis: Transcription factors controlling B-cell development

AbstractTwo structurally dissimilar transcriptional regulators, E2A and Pax-5, have been shown to play essential roles in B-cell development; the p50 subunit of NFκB, by contrast, is required for normal immune responses

Producing The Drunkard with Wing and Drop Design : Construction, Painting, and Use of Roll Drop Scenery

The purpose of this study was to examine 19th century wing and border painting styles and their implementation in the design of The Drunkard or Down with Demon Drink. The play will be referred to as The Drunkard. This play was produced at Doner Auditorium, Brookings, South Dakota, on July 6, 9, and 10, 1988 and at the Prairie Village Opera House, Madison, South Dakota, on July 16, 17, 21, and 22, 1988. Through personal interviews and hands-on training, research was compiled to formulate background information and painting techniques for the seven settings required for production. A brief study of available material indicated that there had been no text written concerning roll drop scenery, although there are texts on painting techniques, pigments, and binders. Roll drop scenery was part of a valuable form of entertainment but there is little documented evidence. Many opera houses that once used roll drops have been abandoned or demolished to make way for progress and numerous artifacts for study have been lost with them. It is hoped that this study will inspire others to research and learn the painting techniques that were so valuable to a scenic artist. A study of this nature may also supply the information needed for some communities to use multiple roll drop scenery. Since no previous study has been conducted concerning roll drop scenery, the information in this study will be a valuable asset to any individual who wishes to attempt such a fascinating art form. Finally, it is hoped that this study will spark interest in individuals who, like the investigator, mistakenly thought the painting style was too involved to produce successfully on a large scale

Developing Educational Resources for Youth Refugees in New Hampshire

The purpose of this project was to provide educational resources for youth refugees. Southern New Hampshire University (SNHU) Center for New Americans sought to create a youth hygiene program. This project used an Instructor-Led model based in a classroom setting. The results were that the youth refugees who attend SNHU Center for New Americans are provided with an educational lesson in personal hygiene practices. It also provided the youth refugees with personal products that helped engage them in the lesson, which made the project more hands-on and appealing to this population. The objective was for SNHU Center for New Americans youth refugees the opportunity to ask questions and learn about hygiene in a comfortable instructor-based lesson. The lesson sparked interest in the youth refugees with a result of educated youth who can refer to this as needed