1,421 research outputs found

    Lydolph, Paul E. Geography of the U.R.S.S. John Wiley and Sons, New York, 1964.

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    To the Arctic, An Introduction to the Far Northern World, by Steven B. Young

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    Problems of Greenlandic Society: Report on a Symposium

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    The following commentary is based upon ten papers on Greenland which were presented at the fourth international congress of the Foundation Française d'Etudes Nordiques held in France in 1969. The papers, two in French and the remainder in English, which appear in the published proceedings of the congress under the collective title "Greenland Today and Tomorrow", constitute a unique symposium on the affairs of the island. Although he attended the congress as a member of the United States delegation, the writer has relied on the published proceedings rather than personal recollections which have become diminished with the passage of time. The authors of the papers are all referred to below in their capacities at the time the congress was held. &hellip

    Expression of Human Immunodeficiency Virus Type 1 Gag Protein Precursor and Envelope Proteins from a Vesicular Stomatitis Virus Recombinant: High-Level Production of Virus-like Particles Containing HIV Envelope

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    AbstractRecombinant vesicular stomatitis viruses have been developed as high-level expression vectors which serve as effective vaccine vectors in animals (Roberts et al., 1998, J. Virol. 72, 4704–4711; Roberts et al., 1999, J. Virol. 73, 3723–3732). Here we show that two genes can be expressed simultaneously from a single, live-attenuated VSV recombinant. The genes used encode the Pr55gag protein precursor of HIV-1 (1.7-kb gene) and an HIV-1 envelope (Env) protein (2.4 kb gene). Our results show that VSV can accommodate up to a 40% increase in genome size with only a threefold reduction in virus titer. Recombinants expressing the Pr55gag protein precursor with or without Env protein produced abundant HIV virus-like particles (VLPs) in addition to bullet-shaped VSV particles. HIV Env protein expressed from a VSV recombinant also expressing Gag was specifically incorporated into the HIV VLPs but not into the VSV particles. In contrast, VSV G protein was found in both VSV particles and in HIV VLPs. Such VSV/HIV recombinants producing HIV VLPs with Env protein could be an effective source of HIV-like particles inducing both cellular and antibody-mediated immunity to HIV-1

    Measure Guideline. Energy-Efficient Window Performance and Selection

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    This document provides guidelines for the selection of energy-efficient windows in new and existing residential construction in all US climate zones. It includes information on window products, their attributes and performance. It provides cost/benefit information on window energy savings as well as information on non-energy benefits such as thermal comfort and reduced HVAC demands. The document also provides information on energy impacts of design decisions such as window orientation, total glazing area and shading devices and conditions. Information on resources for proper window installation is included as well. This document is for builders, homeowners, designers and anyone making decisions about selecting energy efficient window. It is intended to complement other Building America information and efforts

    Optically-Triggered Nanoscale Memory Effect in a Hybrid Plasmonic-Phase Changing Nanostructure

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    Nanoscale devices, such as all-optical modulators and electro-optical transducers, can be implemented in heterostructures that integrate plasmonic nanostructures with functional active materials. Here we demonstrate all-optical control of a nanoscale memory effect in such a heterostructure by coupling the localized surface plasmon resonance (LSPR) of gold nanodisk arrays to a phase-changing material (PCM), vanadium dioxide (VO<inf>2</inf>). By latching the VO<inf>2</inf> in a distinct correlated metallic state during the insulator-to-metal transition (IMT), while concurrently exciting the hybrid nanostructure with one or more ultraviolet optical pulses, the entire phase space of this correlated state can be accessed optically to modulate the plasmon response. We find that the LSPR modulation depends strongly but linearly on the initial latched state, suggesting that the memory effect encoded in the plasmon resonance wavelength is linked to the strongly correlated electron states of the VO<inf>2</inf>. The continuous, linear variation of the electronic and optical properties of these model heterostructures opens the way to multiple design strategies for hybrid devices with novel optoelectronic functionalities, which can be controlled by an applied electric or optical field, strain, injected charge, or temperature.Department of Applied Physic

    Quasisymmetric Schur functions

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    We introduce a new basis for quasisymmetric functions, which arise from a specialization of nonsymmetric Macdonald polynomials to standard bases, also known as Demazure atoms. Our new basis is called the basis of quasisymmetric Schur functions, since the basis elements refine Schur functions in a natural way. We derive expansions for quasisymmetric Schur functions in terms of monomial and fundamental quasisymmetric functions, which give rise to quasisymmetric refinements of Kostka numbers and standard (reverse) tableaux. From here we derive a Pieri rule for quasisymmetric Schur functions that naturally refines the Pieri rule for Schur functions. After surveying combinatorial formulas for Macdonald polynomials, including an expansion of Macdonald polynomials into fundamental quasisymmetric functions, we show how some of our results can be extended to include the tt parameter from Hall-Littlewood theory.Comment: 30 pages; references added; new subsections on transition matrices, how to include the tt parameter from Hall-Littlewood theory and further avenues; new survey of combinatorial formulas for Macdonald polynomials, including an expansion of Macdonald polynomials into fundamental quasisymmetric function

    Constructing a folding model for protein S6 guided by native fluctuations deduced from NMR structures

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    The diversity in a set of protein nuclear magnetic resonance (NMR) structures provides an estimate of native state fluctuations that can be used to refine and enrich structure-based protein models (SBMs). Dynamics are an essential part of a protein’s functional native state. The dynamics in the native state are controlled by the same funneled energy landscape that guides the entire folding process. SBMs apply the principle of minimal frustration, drawn from energy landscape theory, to construct a funneled folding landscape for a given protein using only information from the native structure. On an energy landscape smoothed by evolution towards minimal frustration, geometrical constraints, imposed by the native structure, control the folding mechanism and shape the native dynamics revealed by the model. Native-state fluctuations can alternatively be estimated directly from the diversity in the set of NMRstructures for a protein. Based on this information, we identify a highly flexible loop in the ribosomal protein S6 and modify the contact map in a SBM to accommodate the inferred dynamics. By taking into account the probable native state dynamics, the experimental transition state is recovered in the model, and the correct order of folding events is restored. Our study highlights how the shared energy landscape connects folding and function by showing that a better description of the native basin improves the prediction of the folding mechanism
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