733 research outputs found
Dansgaard-Oeschger forcing of sea surface temperature variability in the midlatitude North Atlantic between 500 and 400 ka (MIS 12)
Magnetoresistance due to Domain Walls in Micron Scale Fe Wires with Stripe Domains
The magnetoresistance (MR) associated with domain boundaries has been
investigated in microfabricated bcc Fe (0.65 to 20 m linewidth) wires with
controlled stripe domains. Domain configurations have been characterized using
magnetic force microscopy. MR measurements as a function of field angle,
temperature and domain configuration are used to estimate MR contributions due
to resistivity anisotropy and domain walls. Evidence is presented that domain
boundaries enhance the conductivity in such microstructures over a broad range
of temperatures (1.5 K to 80 K).Comment: 8 pages, 3 postscript figures, and 2 jpg images (Fig 1 and 2) to
appear in IEEE Transactions on Magnetics (Fall 1998
Demonstration of detuned dual recycling at the Garching 30m laser interferometer
Dual recycling is an advanced optical technique to enhance the
signal-to-noise ratio of laser interferometric gravitational wave detectors in
a limited bandwidth. To optimise the center of this band with respect to
Fourier frequencies of expected gravitational wave signals detuned dual
recycling has to be implemented. We demonstrated detuned dual recycling on a
fully suspended 30m prototype interferometer. A control scheme that allows to
tune the detector to different frequencies will be outlined. Good agreement
between the experimental results and numerical simulations has been achieved.Comment: 9 page
Ballistic and diffuse transport through a ferromagnetic domain wall
We study transport through ballistic and diffuse ferromagnetic domain walls
in a two-band Stoner model with a rotating magnetization direction. For a
ballistic domain wall, the change in the conductance due to the domain wall
scattering is obtained from an adiabatic approximation valid when the length of
the domain wall is much longer than the Fermi wavelength. In diffuse systems,
the change in the resistivity is calculated using a diagrammatic technique to
the lowest order in the domain wall scattering and taking into account
spin-dependent scattering lifetimes and screening of the domain wall potential.Comment: 9 pages, 3 figures, to appear in Phys. Rev.
Enhancing Developing Country Access to Eco-Innovation: The Case of Technology Transfer and Climate Change in a Post-2012 Policy Framework
The deployment of eco-innovations in developing countries is a key driver of their contribution to efficiently addressing global environmental challenges. It is also a key driver of markets for eco-innovation and sustainable economic development. This report explores the barriers developing countries face in accessing markets for eco-innovation. It outlines the key considerations policy needs to address to overcome these barriers and discusses the extent to which selected existing policy mechanisms and organisation have achieved this. The key finding of the report is that the majority of existing policy mechanisms fails to recognise the critical importance of developing indigenous eco-innovation capabilities amongst developing country firms. Indigenous eco-innovation capabilities are essential to facilitating both the diffusion of existing ecoinnovations within developing countries and sustainable economic development based on the adoption, adaption and development of environmentally sound technologies that fit with the bespoke conditions faced by developing countries. Building up eco-innovation capabilities in developing countries requires a shift away from the current focus on large project based approaches which emphasise the transfer of the hardware aspects of clean technologies, towards approaches that emphasise flows of codified knowledge (know-how and know-why) and tacit knowledge. Policy also needs to be improved to better respond to the context-specific technological and cultural requirements which vary inter- and intra-nationally
The Sun's Preferred Longitudes and the Coupling of Magnetic Dynamo Modes
Observations show that solar activity is distributed non-axisymmetrically,
concentrating at "preferred longitudes". This indicates the important role of
non-axisymmetric magnetic fields in the origin of solar activity. We
investigate the generation of the non-axisymmetric fields and their coupling
with axisymmetric solar magnetic field. Our kinematic generation (dynamo) model
operating in a sphere includes solar differential rotation, which approximates
the differential rotation obtained by inversion of helioseismic data, modelled
distributions of the turbulent resistivity, non-axisymmetric mean helicity, and
meridional circulation in the convection zone. We find that (1) the
non-axisymmetric modes are localised near the base of the convection zone,
where the formation of active regions starts, and at latitudes around
; (2) the coupling of non-axisymmetric and axisymmetric modes
causes the non-axisymmetric mode to follow the solar cycle; the phase relations
between the modes are found. (3) The rate of rotation of the first
non-axisymmetric mode is close to that determined in the interplanetary space.Comment: 22 pages, 18 figures. Accepted for publication in the Astrophysical
Journa
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