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Reply to: fMRI replicability depends upon sufficient individual-level data.
A Machian Model of Dark Energy
Einstein believed that Mach's principle should play a major role in finding a
meaningful spacetime geometry, though it was discovered later that his field
equations gave some solutions which were not Machian. It is shown, in this
essay, that the kinematical models, which are invoked to solve the
cosmological constant problem, are in fact consistent with Mach's ideas. One
particular model in this category is described which results from the
microstructure of spacetime and seems to explain the current observations
successfully and also has some benefits over the conventional models. This
forces one to think whether the Mach's ideas and the cosmological constant are
interrelated in some way.Comment: Received an Honorable mention in the Essay Contest-2002 sponsored by
the Gravity Research Foundation; A paragraph added on how the model can
explain the CMB anisotropy observations; To appear in the Classical and
Quantum Gravit
A Chandra ACIS view of the Thermal Composite Supernova Remnant 3C391
We present a 60 ks Chandra ACIS-S observation of the thermal composite
supernova remnant 3C391. The southeast-northwest elongated morphology is
similar to that previously found in radio and X-ray studies. This observation
unveils a highly clumpy structure of the remnant. Detailed spatially resolved
spectral analysis for the small-scale features reveals that the interior gas is
generally of normal metal abundance and has approached or basically reached
ionization equilibrium. The hydrogen column density increases from southeast to
northwest. Three mechanisms, radiative rim, thermal conduction, and cloudlet
evaporation, may all play roles in the X-ray appearance of 3C391 as a "thermal
composite" remnant, but there are difficulties with each of them in explaining
some physical properties. Comparatively, the cloudlet evaporation model is
favored by the main characteristics such as the highly clumpy structure and the
uniform temperature and density distribution over most of the remnant. The
directly measured postshock temperature also implies a young age, about 4 kyr,
for the remnant. The postshock gas pressure derived from the NE and SW rims,
which harbor maser spots, is consistent with the estimate for the maser
regions. An unresolved X-ray source is observed on the northwest border and its
spectrum is best fitted by a power-law.Comment: aastex, 27 pages (including 4 figures), to appear in the ApJ 1 Dec.
2004, v616 issu
Supply chain [Chapter 4]
The Supply Chain is critical to the establishment of a hydrogen fuel cell economy and indeed offers immense benefit to the economy. A range of Lifecycle Analysis studies conducted in EU FC Framework and EU FCH Joint Undertaking projects detailing HFC system inventories readily explains the widespread extent of potential interest showing that the physical bulk of any fuel cell system or application does not involve a great deal of new technology. Although the core fuel cell (or electrolysis) stack is fundamental to the technology – the physical bulk of any system or application is made up of regular engineering and fabricated components. And the greatest proportion of cost and value in such systems is entrained in their overall design and integration content (IP). For example in scoping out the prospects for a hydrogen ferry being built and operated in Scotland, around 200 local supply chain companies were identified which could have an interest in such a development
Optical fiber interferometer for the study of ultrasonic waves in composite materials
The possibility of acoustic emission detection in composites using embedded optical fibers as sensing elements was investigated. Optical fiber interferometry, fiber acoustic sensitivity, fiber interferometer calibration, and acoustic emission detection are reported. Adhesive bond layer dynamical properties using ultrasonic interface waves, the design and construction of an ultrasonic transducer with a two dimensional Gaussian pressure profile, and the development of an optical differential technique for the measurement of surface acoustic wave particle displacements and propagation direction are also examined
On wave interference in planet migration: dead zone torques modified by active zone forcing
We investigate planetary migration in the dead zone of a protoplanetary disk
where there are a set of spiral waves propagating inward due to the turbulence
in the active zone and the Rossby wave instability (RWI), which occurs at the
transition between the dead and active zones. We perform global 3D unstratified
magnetohydrodynamical (MHD) simulations of a gaseous disk with the FARGO3D
code, using weak gradients in the static resistivity profiles that trigger the
formation of a vortex at the outer edge of the dead zone. We find that once the
Rossby vortex develops, spiral waves in the dead zone emerge and interact with
embedded migrating planets by wave interference, which notably changes their
migration. The inward migration becomes faster depending on the mass of the
planet, due mostly to the constructive (destructive) interference between the
outer (inner) spiral arm of the planet and, the destruction of the dynamics of
the horseshoe region by means of the set of background spiral waves propagating
inward. The constructive wave interference produces a more negative Lindblad
differential torque which inevitably leads to an inward migration. Lastly, for
massive planets embedded in the dead zone, we find that the spiral waves can
create an asymmetric wider and depeer gap than in the case of -disks,
and can prevent the formation of vortices at the outer edge of the gap. The
latter could generate a faster or slower migration compared to the standard
type-II migration.Comment: 18 pages, 14 figures, accepted for publication in Ap
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