99,660 research outputs found
Queen Conch ranching and educational outreach as part of the Seaflower Biosphere Reserve, Colombia
’Eyes free’ in-car assistance: parent and child passenger collaboration during phone calls
This paper examines routine family car journeys, looking specifically at how passengers assist during a mobile telephone call while the drivers address the competing demands of handling the vehicle, interacting with various artefacts and controls in the cabin, and engage in co-located and remote conversations while navigating through busy city roads. Based on an analysis of video fragments, we see how drivers and child passengers form their conversations and requests around the call so as to be meaningful and paced to the demands, knowledge and abilities of their cooccupants, and how the conditions of the road and emergent traffic are oriented to and negotiated in the context of the social interaction that they exist alongside. The study provides implications for the design of car-based collaborative media and considers how hands- and eyesfree natural interfaces could be tailored to the complexity of activities in the car and on the road
Covariant spectator theory of np scattering: Phase shifts obtained from precision fits to data below 350 MeV
Using the covariant spectator theory (CST), we present two one boson exchange
kernels that have been successfully adjusted to fit the 2007 world np data
(containing 3788 data) below 350 MeV. One model (which we designate WJC-1) has
27 parameters and fits with a chi2/N = 1.06. The other model (designated WJC-2)
has only 15 parameters and fits with a chi2/N = 1.12. Both of these models also
reproduce the experimental triton binding energy without introducing additional
irreducible three-nucleon forces. One result of this work is a new phase shift
analysis, updated for all data until 2006, which is useful even if one does not
work within the CST. In carrying out these fits we have reviewed the entire
data base, adding new data not previously used in other high precision fits and
restoring some data omitted in previous fits. A full discussion and evaluation
of the 2007 data base is presented.Comment: 43 pages, 27 figures, and 13 table
The ground state energy of a massive scalar field in the background of a semi-transparent spherical shell
We calculate the zero point energy of a massive scalar field in the
background of an infinitely thin spherical shell given by a potential of the
delta function type. We use zeta functional regularization and express the
regularized ground state energy in terms of the Jost function of the related
scattering problem. Then we find the corresponding heat kernel coefficients and
perform the renormalization, imposing the normalization condition that the
ground state energy vanishes when the mass of the quantum field becomes large.
Finally the ground state energy is calculated numerically. Corresponding plots
are given for different values of the strength of the background potential, for
both attractive and repulsive potentials.Comment: 15 pages, 5 figure
Observation of the March Maximum in the Daemon Flux from Neos in the Year 2005: New Efforts and New Effects
The experiments of 2005 aimed at detection of low-velocity (~10-15 km s-1)
daemons falling on to the Earth's surface from Near-Earth, Almost Circular
Heliocentric Orbits (NEACHOs) have corroborated once more the existence of the
March maximum in their flux by raising its confidence level to 99.99%. In
addition, these experiments permitted us to identify several FEU-167-1-type PM
tubes, with a few times thicker inner Al coating, which appear to be capable to
detect, without any scintillator, the crossing of negatively charged daemons.
As a result, detection efficiency increases tens of times, thus raising the
measured level of the March daemon flux to f > 0.5E-7 cm-2s-1.Comment: 14 page
Inverse Scattering and Acousto-Optic Imaging
We propose a tomographic method to reconstruct the optical properties of a
highly-scattering medium from incoherent acousto-optic measurements. The method
is based on the solution to an inverse problem for the diffusion equation and
makes use of the principle of interior control of boundary measurements by an
external wave field.Comment: 10 page
Phase transition in the globalization of trade
Globalization processes interweave economic structures at a worldwide scale,
trade playing a central role as one of the elemental channels of interaction
among countries. Despite the significance of such phenomena, measuring economic
globalization still remains an open problem. More quantitative treatments could
improve the understanding of globalization at the same time that help a formal
basis for comparative economic history. In this letter, we investigate the time
evolution of the statistical properties of bilateral trade imbalances between
countries in the trade system. We measure their cumulative probability
distribution at different moments in time to discover a sudden transition circa
1960 from a regime where the distribution was always represented by a steady
characteristic function to a new state where the distribution dilates as time
goes on. This suggests that the rule that was governing the statistical
behavior of bilateral trade imbalances until the 60's abruptly changed to a new
form persistent in the last decades. In the new regime, the figures for the
different years collapse into a universal master curve when rescaled by the
corresponding global gross domestic product value. This coupling points to an
increased interdependence of world economies and its onset corresponds in time
with the starting of the last globalization wave.Comment: Final versio
Coherent spin manipulation in an exchange-only qubit
Initialization, manipulation, and measurement of a three-spin qubit are
demonstrated using a few-electron triple quantum dot, where all operations can
be driven by tuning the nearest-neighbor exchange interaction. Multiplexed
reflectometry, applied to two nearby charge sensors, allows for qubit readout.
Decoherence is found to be consistent with predictions based on gate voltage
noise with a uniform power spectrum. The theory of the exchange-only qubit is
developed and it is shown that initialization of only two spins suffices for
operation. Requirements for full multi-qubit control using only exchange and
electrostatic interactions are outlined.Comment: related work at http://marcuslab.harvard.ed
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