11,687 research outputs found
Forming aluminum for solar energy concentrators Quarterly progress report no. 2, 1 Jan. - 31 Mar. 1964
Electroformed aluminum solar reflector
Conserved Aspartate Residues and Phosphorylation in Signal Transduction by the Chemotaxis Protein CheY
The CheY protein is phosphorylated by CheA and dephosphorylated by CheZ as part of the chemotactic signal transduction pathway in Escherichia coli. Phosphorylation of CheY has been proposed to occur on an aspartate residue. Each of the eight aspartate residues of CheY was replaced by using site-directed mutagenesis. Substitutions at Asp-12, Asp-13, or Asp-57 resulted in loss of chemotaxis. Most of the mutant CheY proteins were still phosphorylated by CheA but exhibited modified biochemical properties, including reduced ability to accept phosphate from CheA, altered phosphate group stability, and/or resistance to CheZ-mediated dephosphorylation. The properties of CheY proteins bearing a substitution at position 57 were most aberrant, consistent with the hypothesis that Asp-57 is the normal site of acyl phosphate formation. Evidence for an alternate site of phosphorylation in the Asp-57 mutants is presented. Phosphorylated CheY is believed to cause tumbling behavior. However, a dominant mutant CheY protein that was not phosphorylated in vitro caused tumbling in vivo in the absence of CheA. This phenotype suggests that the role of phosphorylation in the wild-type CheY protein is to stabilize a transient conformational change that can generate tumbling behavior
Tourism Industry Financing of Climate Change Adaptation: Exploring the Potential in Small Island Developing States
In many small island developing states (SIDS), tourism is a principal driver of the economy and of infrastructure development. The SIDS’ tourism sector is, however, threatened by climate change impacts, which will likely incur high costs for climate change adaptation (CCA). Discussions are starting about who should pay for the costs of adapting to climate change, especially the balance amongst sectors such as between governments and the tourism industry. Through the perceptions of selected industry stakeholders, this study explores the potential of the tourism industry in SIDS in financing its own CCA. Fiscal and political mechanisms were examined, such as adaptation taxes and levies, adaptation funds, building regulations, and risk transference. The study’s exploratory method combines nine in-depth key stakeholder interviews from various SIDS and an extensive literature review to develop a schematic of suggested mechanisms. The results reveal a high overall potential for the tourism industry funding its CCA, but with significant challenges in realizing this potential. Consumer expectations and demands, governmental hesitation in creating perceived investment barriers, and assumptions about cost effectiveness could undermine steps moving forward. Varying incentive structures, the sector’s price sensitivity, and the differing abilities of tourism industry stakeholders to adapt are factors suggesting that government frameworks are needed to ensure effective and substantive action
Electronic structure of multiquantum giant vortex states in mesoscopic superconducting disks
We report self-consistent calculations of the microscopic electronic
structure of the so-called giant vortex states. These novel multiquantum vortex
states, detected by recent magnetization measurements on submicron disks, are
qualitatively different from the Abrikosov vortices in the bulk. We find that,
in addition to multiple branches of bound states in the core region, the local
tunneling density of states exhibits Tomasch oscillations due to the
single-particle interference arising from quantum confinement. These features
should be directly observable by scanning tunneling spectroscopy.Comment: 5 pages, 4 figure
Star-shaped Local Density of States around Vortices in a Type II Superconductor
The electronic structure of vortices in a type II superconductor is analyzed
within the quasi-classical Eilenberger framework. The possible origin of a
sixfold ``star'' shape of the local density of states, observed by scanning
tunneling microscope experiments on NbSe, is examined in the light of the
three effects; the anisotropic pairing, the vortex lattice, and the anisotropic
density of states at the Fermi surface. Outstanding features of split parallel
rays of this star are well explained in terms of an anisotropic -wave
pairing. This reveals a rich internal electronic structure associated with a
vortex core.Comment: 4 pages, REVTeX, 3 figures available upon reques
Assessing Accommodation Suppliers' Perceptions of Climate Change Adaptation Actions on Koh Phi Phi Island, Thailand
Koh Phi Phi Don is among the most visited island tourism destinations in Thailand. Due to the island’s topography and development patterns, most accommodation suppliers on the island are likely to be exposed to a range of climate change impacts, particularly sea-level rise, which can pose a severe risk to the local tourism operations. This study aimed to explore perceptions of climate change adaptation actions in response to impacts typically associated with climate change. This study, furthermore, investigated possible obstacles, barriers, and incentives influencing decision-making processes of accommodation owner-managers (the private sector) to adapt to climate change. The investigation builds on 81 surveys and 12 in-depth interviews. The findings provide evidence that most of the sampled businesses already implemented (consciously or not) climate change adaptation measures, such as insurance coverage, water treatment appliances, and staff training on emergency responses. Through a concentration of power on the island, their action is hindered, which creates a barrier to a sustainable and climate risk-informed development pathway
Optical properties of aerosols and clouds: The software package OPAC
The software package OPAC (Optical Properties of Aerosols and Clouds) is described. It easily provides optical properties in the solar and terrestrial spectral range of atmospheric particulate matter. Microphysical and optical properties of six water clouds, three ice clouds, and 10 aerosol components, which are considered as typical cases, are stored as ASCII files. The optical properties are the extinction, scattering, and absorption coefficients, the single scattering albedo, the asymmetry parameter, and the phase function. They are calculated on the basis of the microphysical data (size distribution and spectral refractive index) under the assumption of spherical particles in case of aerosols and cloud droplets and assuming hexagonal columns in case of cirrus clouds. Data are given for up to 61 wavelengths between 0.25 and 40 mu m and up to eight values of the relative humidity. The software package also allows calculation of derived optical properties like mass extinction coefficients and Angstrom coefficients. Real aerosol in the atmosphere always is a mixture of different components. Thus, in OPAC it is made possible to get optical properties of any mixtures of the basic components and to calculate optical depths on the base of exponential aerosol height profiles. Typical mixtures of aerosol components as well as typical height profiles are proposed as default values, but mixtures and profiles for the description of individual cases may also be achieved simply
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