5,381 research outputs found
Multi-disciplinary Investigation of the Windows of John Thornton, focusing on the Great East Window of York Minster
Twenty-seven samples of glass from panel 2e of John Thorntonâs Great East Window (1405â1408) at York Minster have been analyzed using energy dispersive x-ray analysis in the scanning electron microscope. This paper highlights our findings. Inserts and replacements of early modern and medieval glass have been identifi ed. White (colorless) and colored medieval glass differ significantly in composition, suggesting diff erent sources. Eleven samples of white glass original to the window are identical within analytical error, suggesting they came from the same batch, but the head of Christ is from another panel. Blue and flashed red glass were each the product of more than one batch of melting. Primarily, the condition of the glass is dependent upon silica content. Further investigations of other panels from the Great East Window, and of other windows by Thornton, are ongoing
A new approach to the solar oxygen abundance problem
In this work we present new data that sets strong constraints on the solar
oxygen abundance. Our approach, based on the analysis of spectro-polarimetric
observations, is almost model-independent and therefore extremely robust. The
asymmetry of the Stokes V profile of the 6300 A [OI] and NiI blend is used as
an indicator of the relative abundances of these two elements. The peculiar
shape of the profile requires a value of EO = 730+/-100 ppm (parts per
million), or logEO = 8.86+/-0.07 in the logarithmic scale commonly used in
Astrophysics. The uncertainty range includes the model dependence as well as
uncertainties in the oscillator strengths of the lines. We emphasize that the
very low degree of model dependence in our analysis makes it very reliable
compared to traditional determinations.Comment: Accepted for publication in The Astrophysical Journal Letters. 12
pages, 3 figures, referee format. This is the replacement of a previous
version of the paper. Our revised analysis takes into consideration the
formation of molecules, resulting in a substantially larger value for the
derived Oxygen abundanc
Is the Sun Lighter than the Earth? Isotopic CO in the Photosphere, Viewed through the Lens of 3D Spectrum Synthesis
We consider the formation of solar infrared (2-6 micron) rovibrational bands
of carbon monoxide (CO) in CO5BOLD 3D convection models, with the aim to refine
abundances of the heavy isotopes of carbon (13C) and oxygen (18O,17O), to
compare with direct capture measurements of solar wind light ions by the
Genesis Discovery Mission. We find that previous, mainly 1D, analyses were
systematically biased toward lower isotopic ratios (e.g., R23= 12C/13C),
suggesting an isotopically "heavy" Sun contrary to accepted fractionation
processes thought to have operated in the primitive solar nebula. The new 3D
ratios for 13C and 18O are: R23= 91.4 +/- 1.3 (Rsun= 89.2); and R68= 511 +/- 10
(Rsun= 499), where the uncertainties are 1 sigma and "optimistic." We also
obtained R67= 2738 +/- 118 (Rsun= 2632), but we caution that the observed
12C17O features are extremely weak. The new solar ratios for the oxygen
isotopes fall between the terrestrial values and those reported by Genesis
(R68= 530, R6= 2798), although including both within 2 sigma error flags, and
go in the direction favoring recent theories for the oxygen isotope composition
of Ca-Al inclusions (CAI) in primitive meteorites. While not a major focus of
this work, we derive an oxygen abundance of 603 +/- 9 ppm (relative to
hydrogen; 8.78 on the logarithmic H= 12 scale). That the Sun likely is lighter
than the Earth, isotopically speaking, removes the necessity to invoke exotic
fractionation processes during the early construction of the inner solar
system
Offshore Pipeline Corridors and Landfalls in Coastal Virginia Volume One
This report is a product of the Virginia Coastal Resources Management (CRM) Program. Along with other coastal states, Virginia is preparing a management program for coastal land and water resources and uses under grants from the Office of Coastal Zone Management (OCZM), of the U.S. Department of Commerce. The Coastal Zone Management Act of 1972, as amended in 1976, enumerates the elements which coastal states and their political subdivisions must include in their program. This report commences the response of the Commonwealth of Virginia to the national concern expressed in Sec. 305(B) (8) of the Act, that is, that states should develop a process for planning the location of energy facilities and for managing their effects on coastal resources. This report is a planning effort aimed at anticipating and planning for the implications of oil and gas drilling on the Atlantic Continental Shelf. Specifically, it is designed to provide technical information on pipeline siting and construction requirements as well as on the potential environmental impacts associated with pipelines. It is intended to assist state and local officials in making decisions about pipelines coming ashore in Virginia-whether to allow or not allow pipelines and, if they are to be allowed, to determine the coastal areas which would be most suitable as landfall sites. The report does not intend to promote or discourage pipelines but rather to Identify and discuss the range of potential problems and opportunities associated with pipeline activities. In addition, this is a technical planning document only and does not attempt to establish policy for the Commonwealth of Virginia with respect to pipelines or any other OCS activity. Every effort has been made to use the most current and accurate resources available and to be objective as possible in presenting the facts and conclusions of this report
Offshore Pipeline Corridors and Landfalls in Coastal Virginia Volume Two - Appendices
This report is a product the Virginia Coastal Resources Management (CRM) Program. Along with other coastal states, Virginia is preparing a mangement program for coastal land water resources and uses under grants from the Office of Coastal Zone Management (OCZM), National Oceanic and Atmospheric Administration, of the U.S. Department of Commerce. The Coastal Zone Management Act of 1972, as amended in 1976, enumerates the elements which coastal states and their political subdivisions must include in their program. This report commences the response of the Comm~nwealth of Virginia to the national concern expressed in Sec. 305(B) (8) of the Act, that is, that states should develop a process for planning the location of energy facilities and for managing their effects on coastal resources. This report is a planning effort aimed at anticipating and planning for the implications of oil and gas drilling on the Atlantic Continental Shelf. Specifically, it is designed to provide technical information on pipeline siting and construction requirements as well as on the potential environmental impacts associated with pipelines. It is intended to assist state and local officials in making decisions about pipelines coming ashore in Virginia-whether to allow or not allow pipelines and, if they are to be allowed, to determine the coastal areas which would be most suitable as landfall sites. The report does not intent to promote or discourage pipelines but rather to identify and discuss the range of potential problems and opportunities associated with pipeline activities. In addition, this is a technical planning document and it does not attempt to establish policy for the Commonwealth of Virginia with respect to pipelines or any other OCS activity. Every effort has been made to use the most current and accurate resources available and to be objective as possible in presenting the facts and conclusions of this report
51 Pegasi - a planet-bearing Maunder minimum candidate
We observed 51 Peg, the first detected planet-bearing star, in a 55 ks
XMM-Newton pointing and in 5 ks pointings each with Chandra HRC-I and ACIS-S.
The star has a very low count rate in the XMM observation, but is clearly
visible in the Chandra images due to the detectors' different sensitivity at
low X-ray energies. This allows a temperature estimate for 51 Peg's corona of
T<1MK; the detected ACIS-S photons can be plausibly explained by emission lines
of a very cool plasma near 200eV. The constantly low X-ray surface flux and the
flat-activity profile seen in optical CaII data suggest that 51 Peg is a
Maunder minimum star; an activity enhancement due to a Hot Jupiter, as proposed
by recent studies, seems to be absent. The star's X-ray fluxes in different
instruments are consistent with the exception of the HRC Imager, which might
have a larger effective area below 200eV than given in the calibration.Comment: accepted by A&
A systematic review of associations between environmental exposures and development of asthma in children aged up to 9 years
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.Peer reviewedPublisher PD
Computer Integrated Manufacturing and Employment: Methodological Problems of Estimating the Employment Effects of CIM Application on the Macroeconomic Level
This paper is one of the first research products of the newly established Computer Integrated Manufacturing (CIM) Project, of which Prof. Ayres is the leader. It addresses issues of occupation-by-sector data availability, international comparability, and suitability for use with formal I-O models. Methods of estimating labor substitutability by CIM are also discussed, along with some early estimates of the impact of robotics on employment. The paper was formally presented at a session of the American Economic Association meeting in New Orleans, December 30, 1986. As an IIASA working paper it will be available to collaborating researchers and institutions in other countries
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