484 research outputs found
Ten Low Mass Companions from the Keck Precision Velocity Survey
Ten new low mass companions have emerged from the Keck precision Doppler
velocity survey, with minimum (msini) masses ranging from 0.8 mjup to 0.34
msun. Five of these are planet candidates with msini < 12 mjup, two are brown
dwarf candidates with msini ~30 mjup, and three are low mass stellar
companions. Hipparcos astrometry reveals the orbital inclinations and masses
for three of the (more massive) companions, and it provides upper limits to the
masses for the rest. A new class of extrasolar planet is emerging,
characterized by nearly circular orbits and orbital radii greater than 1 AU.
The planet HD 4208b appears to be a member of this new class. The mass
distribution of extrasolar planets continues to exhibit a rapid rise from 10
mjup toward the lowest detectable masses near 1 msat.Comment: 26 pages, TeX, plus 13 postscript figure
Heat Kernel Expansion for Semitransparent Boundaries
We study the heat kernel for an operator of Laplace type with a
-function potential concentrated on a closed surface. We derive the
general form of the small asymptotics and calculate explicitly several
first heat kernel coefficients.Comment: 16 page
Multisensory integration across exteroceptive and interoceptive domains modulates self-experience in the rubber-hand illusion
Identifying with a body is central to being a conscious self. The now classic ârubber hand illusionâ demonstrates that the experience of body ownership can be modulated by manipulating the timing of exteroceptive(visual and tactile)body-related feedback. Moreover,the strength of this modulation is related to individual differences in sensitivity to internal bodily signals(interoception). However the interaction of exteroceptive and interoceptive signals in determining the experience of body-ownership within an individual remains poorly understood.Here, we demonstrate that this depends on the online integration of exteroceptive and interoceptive signals by implementing an innovative âcardiac rubber hand illusionâ that combined computer-generated augmented-reality with feedback of interoceptive (cardiac) information. We show that both subjective and objective measures of virtual-hand ownership are enhanced by cardio-visual feedback in-time with the actual heartbeat,as compared to asynchronous feedback. We further show that these measures correlate with individual differences in interoceptive sensitivity,and are also modulated by the integration of proprioceptive signals instantiated using real-time visual remapping of finger movements to the virtual hand.Our results demonstrate that interoceptive signals directly influence the experience of body ownership via multisensory integration,and they lend support to models of conscious selfhood based on interoceptive predictive coding
Further functional determinants
Functional determinants for the scalar Laplacian on spherical caps and
slices, flat balls, shells and generalised cylinders are evaluated in two,
three and four dimensions using conformal techniques. Both Dirichlet and Robin
boundary conditions are allowed for. Some effects of non-smooth boundaries are
discussed; in particular the 3-hemiball and the 3-hemishell are considered. The
edge and vertex contributions to the coefficient are examined.Comment: 25 p,JyTex,5 figs. on request
Whightman function and scalar Casimir densities for a wedge with a cylindrical boundary
Whightman function, vacuum expectation values of the field square, and the
energy-momentum tensor are investigated for a scalar field inside a wedge with
and without a coaxial cylindrical boundary. Dirichlet boundary conditions are
assumed on the bounding surfaces. The vacuum energy-momentum tensor is
evaluated in the general case of the curvature coupling parameter. Making use
of a variant of the generalized Abel-Plana formula, expectation values are
presented as the sum of two terms. The first one corresponds to the geometry
without a cylindrical boundary and the second one is induced by the presence of
this boundary. The asymptotic behaviour of the field square, vacuum energy
density and stresses near the boundaries are investigated. The additional
vacuum forces acting on the wedge sides due the presence of the cylindrical
boundary are evaluated and it is shown that these forces are attractive. As a
limiting case, the geometry of two parallel plates perpendicularly intersected
by a third one is analyzed.Comment: 19 pages, 6 figures, new section is added on the VEVs for the region
outside the cylidrical shell, discussion and references added, accepted for
publication in J. Phys.
Six New Planets from the Keck Precision Velocity Survey
We report results of a search for planets around 500 main sequence stars
using the Keck high resolution spectrometer which has provided Doppler
precision of 3 m/s during the past 3 yr. We report 6 new strong planet
candidates having complete Keplerian orbits, with periods ranging from 24 d to
3 yr. We also provide updated orbital parameters for 4 previously announced
planets. Four of the six newly discovered planets have minimum Msini masses
less than 2 Mjup, while the remaining two have Msini 5 Mjup. The
distribution of planetary masses continues to exhibit a rise toward lower
masses. The orbital eccentricities of the new planets range from 0.12 to 0.71
which also continues the ubiquity of high eccentricities. All 18 known
extrasolar planets orbiting beyond 0.2 AU have eccentricities greater than
0.1. The current limiting Doppler precision of the Keck Doppler survey is
3 m/s per observation as determined from observations of both stable stars and
residuals to Keplerian fits.Comment: 50 pages with 17 figure
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