2,170 research outputs found
Multipurpose electric furnace system
A multipurpose electric furnace system of advanced design for space applications was developed and tested. This system is intended for use in the Apollo-Soyuz Test Program. It consists of the furnace, control package and a helium package for rapid cooldown
Reconstructing stakeholder relationships using ‘corporate social responsibility’ as a response strategy to cases of corporate irresponsibility: The case of the 2010 BP spill in the Gulf of Mexico.
Purpose When organisations behave irresponsibly, a question remains: Can they use a messaging strategy based in the organisation’s commitment social responsibility to effectively respond to the crisis? The purpose of this chapter is to analyse stakeholder attitudes and their antecedents in such a case. Because of its scope, magnitude and use of a response strategy based on messages of social responsibility, the 2010 BP oil spill in the Gulf of Mexico serves as an excellent case for measuring the effectiveness of such a messaging strategy. Methodology/approach The present study drew from two data sources: a content analysis of interactions on BP’s Facebook page (N=1,515) as well as an image survey of BP (N=749). Findings BP’s messaging strategy had limited positive effects in terms of (1) being viewed as a ‘socially responsible’ organisation and (2) creating significant good will towards the company. However, these data also reveal that BP has effectively opened lines of communication between stakeholders and the company. Practical and social implications This study has two central implications. First, for both organisations and activists, personal investment and the relevance of issues are both critical in order to change stakeholder attitudes about organisations. Second, based on this research, we can begin to develop stakeholder profiles based on age, sex and political identity. Originality/value In the last couple of years, considerable attention has been paid to describing and analysing the response strategies that organisations deploy; however, scant attention has been paid to measuring stakeholder evaluations of those crisis response strategies
Dynamics of mycorrhizae during development of riparian forests along an unregulated river
In this study, we explore two mycorrhizal groups during development of riparian soils along a freely‐flowing river. We provide the first documentation of a shift in abundance between arbuscular mycorrhizae and ectomycorrhizae during floodplain succession. We used a chronosequence spanning 0–70 yr along a river in northwestern Montana, USA, to test the hypothesis that abundance of arbuscular mycorrhizal fungi (AMF) is greatest in early stages of soil development, and abundance of ectomycorrhizal fungi (ECMF) is greatest later in floodplain succession. We also measured the AMF‐mediated process of formation of soil aggregates during site development. AMF colonization of the dominant tree (black cottonwood, Populus trichocarpa) remained low (<5%), while AMF colonization of understory species was high (45–90%), across the chronosequence. Mycorrhizal inoculum potential (MIP) and hyphal length of AMF in soil peaked within the first 13 yr of succession and then declined. No single variable significantly correlated with AMF abundance, but AMF tended to decline as litter and soil organic matter increased. Density of ectomycorrhizal root tips in soil increased linearly throughout the chronosequence, and ectomycorrhizal colonization of cottonwood roots increased rapidly in early stages of succession. These patterns suggest that ECMF are not limited by dispersal, but rather influenced by abundance of host plants. Formation of water stable aggregates increased rapidly during the first third of the chronosequence, which was the period of greatest AMF abundance in the soil. The peak in AMF infectivity and hyphal length during early succession suggests that regular flooding and establishment of new sites promotes AMF abundance in this ecosystem. Regulation of rivers that eliminates creation of new sites may reduce contributions of AMF to riparian areas
Abyssal origin for the early Holocene pulse of unradiogenic neodymium isotopes in Atlantic seawater
The neodymium isotopic composition of authigenic phases of deep-sea sediment cores can be interpreted as reflecting past changes in water-mass mixing proportions if end-member water-mass compositions are constrained through time. Here we present three new records spanning 2480 to 4360 m depth in the North Atlantic Ocean that show seawater Nd isotope values in the early to mid-Holocene that are more radiogenic than values from the abyssal northwest Atlantic. This finding indicates that that the end-member composition of North Atlantic Deep Water was more stable within its core than it was at abyssal depths. The spatial distribution of the unradiogenic neodymium isotope values observed in the North Atlantic suggests a bottom source, and therefore that they were unlikely to have been due to the production of intermediate-depth Labrador Sea Water. We infer that the unradiogenic authigenic Nd isotope values were most likely derived from a pulse of poorly chemically weathered detrital material that was deposited into the Labrador Sea following Laurentide ice sheet retreat in the early Holocene. This unradiogenic sediment released neodymium into the bottom waters, yielding an unradiogenic seawater signal that was advected southward at abyssal depths and attenuated as it vertically mixed upward in the water column to shallower depths. The southward dispersion of these unradiogenic seawater values traces deep-water advection. However, the exact values observed at the most abyssal sites cannot be interpreted as proportionate to the strength of deep-water production without improved constraints on end-member changes
Strontium optical lattice clocks for practical realization of the metre and secondary representation of the second
We present a system of two independent strontium optical lattice standards
probed with a single shared ultra-narrow laser. The absolute frequency of the
clocks can be verified by the use of Er:fiber optical frequency comb with the
GPS-disciplined Rb frequency standard. We report hertz-level spectroscopy of
the clock line and measurements of frequency stability of the two strontium
optical lattice clocks.Comment: This is an author-created, un-copyedited version of an article
accepted for publication in Meas. Sci. Technol. The publisher is not
responsible for any errors or omissions in this version of the manuscript or
any version derived from it. The Version of Record is available online at
doi:10.1088/0957-0233/26/7/07520
An Analysis of the Quantum Penny Flip Game using Geometric Algebra
We analyze the quantum penny flip game using geometric algebra and so
determine all possible unitary transformations which enable the player Q to
implement a winning strategy. Geometric algebra provides a clear visual picture
of the quantum game and its strategies, as well as providing a simple and
direct derivation of the winning transformation, which we demonstrate can be
parametrized by two angles. For comparison we derive the same general winning
strategy by conventional means using density matrices.Comment: 8 Pages, 1 Figure, accepted for publication in the Journal of
Physical Society of Japa
Quantum Matching Pennies Game
A quantum version of the Matching Pennies (MP) game is proposed that is
played using an Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) setting. We construct
the quantum game without using the state vectors, while considering only the
quantum mechanical joint probabilities relevant to the EPR-Bohm setting. We
embed the classical game within the quantum game such that the classical MP
game results when the quantum mechanical joint probabilities become
factorizable. We report new Nash equilibria in the quantum MP game that emerge
when the quantum mechanical joint probabilities maximally violate the
Clauser-Horne-Shimony-Holt form of Bell's inequality.Comment: Revised in light of referees' comments, submitted to Journal of the
Physical Society of Japan, 14 pages, 1 figur
Analysis of two-player quantum games in an EPR setting using geometric algebra
The framework for playing quantum games in an Einstein-Podolsky-Rosen (EPR)
type setting is investigated using the mathematical formalism of Clifford
geometric algebra (GA). In this setting, the players' strategy sets remain
identical to the ones in the classical mixed-strategy version of the game,
which is then obtained as proper subset of the corresponding quantum game. As
examples, using GA we analyze the games of Prisoners' Dilemma and Stag Hunt
when played in the EPR type setting.Comment: 20 pages, no figure, revise
Interacting Binaries with Eccentric Orbits. Secular Orbital Evolution Due To Conservative Mass Transfer
We investigate the secular evolution of the orbital semi-major axis and
eccentricity due to mass transfer in eccentric binaries, assuming conservation
of total system mass and orbital angular momentum. Assuming a delta function
mass transfer rate centered at periastron, we find rates of secular change of
the orbital semi-major axis and eccentricity which are linearly proportional to
the magnitude of the mass transfer rate at periastron. The rates can be
positive as well as negative, so that the semi-major axis and eccentricity can
increase as well as decrease in time. Adopting a delta-function mass-transfer
rate of 10^{-9} M_\sun {\rm yr}^{-1} at periastron yields orbital evolution
timescales ranging from a few Myr to a Hubble time or more, depending on the
binary mass ratio and orbital eccentricity. Comparison with orbital evolution
timescales due to dissipative tides furthermore shows that tides cannot, in all
cases, circularize the orbit rapidly enough to justify the often adopted
assumption of instantaneous circularization at the onset of mass transfer. The
formalism presented can be incorporated in binary evolution and population
synthesis codes to create a self-consistent treatment of mass transfer in
eccentric binaries.Comment: 16 pages, 8 figures, Accepted by The Astrophysical Journa
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