22,016 research outputs found
Do Aid Agencies Have an Ethical Duty to Comply with Researchers? A Response to Rennie.
Medical AID organisations such as MĆ©decins Sans FrontiĆØres receive several requests from individuals and international academic institutions to conduct research at their implementation sites in Africa. Do AID agencies have an ethical duty to comply with research requests? In this paper we respond to the views and constructed theories (albeit unfounded) of one such researcher, whose request to conduct research at one of our sites in the Democratic Republic of Congo was turned down
Characterising small solutions in delay differential equations through numerical approximations
This paper discusses how the existence of small solutions for delay differential equations can be predicted from the behaviour of the spectrum of the finite dimensional approximations.Manchester Centre for Computational Mathematic
Focusing Vacuum Fluctuations II
The quantization of the scalar and electromagnetic fields in the presence of
a parabolic mirror is further developed in the context of a geometric optics
approximation. We extend results in a previous paper to more general
geometries, and also correct an error in one section of that paper. We
calculate the mean squared scalar and electric fields near the focal line of a
parabolic cylindrical mirror. These quantities are found to grow as inverse
powers of the distance from the focus. We give a combination of analytic and
numerical results for the mean squared fields. In particular, we find that the
mean squared electric field can be either negative or positive, depending upon
the choice of parameters. The case of a negative mean squared electric field
corresponds to a repulsive Van der Waals force on an atom near the focus, and
to a region of negative energy density. Similarly, a positive value corresponds
to an attractive force and a possibility of atom trapping in the vicinity of
the focus.Comment: 26 pages, 15 figures; additional discussion added in Sects. IV and I
Neutrinoless Double Beta Decay with SNO+
SNO+ will search for neutrinoless double beta decay by loading 780 tonnes of
linear alkylbenzene liquid scintillator with O(tonne) of neodymium. Using
natural Nd at 0.1% loading will provide 43.7 kg of 150Nd given its 5.6%
abundance and allow the experiment to reach a sensitivity to the effective
neutrino mass of 100-200 meV at 90% C.L in a 3 year run. The SNO+ detector has
ultra low backgrounds with 7000 tonnes of water shielding and self-shielding of
the scintillator. Distillation and several other purification techniques will
be used with the aim of achieving Borexino levels of backgrounds. The
experiment is fully funded and data taking with light-water will commence in
2012 with scintillator data following in 2013.Comment: 4 pages, 2 figures, prepared for TAUP 201
Does the Third Law of Thermodynamics hold in the Quantum Regime?
The first in a long series of papers by John T. Lewis,
G. W. Ford and the present author, considered the problem of the most general
coupling of a quantum particle to a linear passive heat bath, in the course of
which they derived an exact formula for the free energy of an oscillator
coupled to a heat bath in thermal equilibrium at temperature T. This formula,
and its later extension to three dimensions to incorporate a magnetic field,
has proved to be invaluable in analyzing problems in quantum thermodynamics.
Here, we address the question raised in our title viz. Nernst's third law of
thermodynamics
Gravitons and Lightcone Fluctuations II: Correlation Functions
A model of a fluctuating lightcone due to a bath of gravitons is further
investigated. The flight times of photons between a source and a detector may
be either longer or shorter than the light propagation time in the background
classical spacetime, and will form a Gaussian distribution centered around the
classical flight time. However, a pair of photons emitted in rapid succession
will tend to have correlated flight times. We derive and discuss a correlation
function which describes this effect. This enables us to understand more fully
the operational significance of a fluctuating lightcone. Our results may be
combined with observational data on pulsar timing to place some constraints on
the quantum state of cosmological gravitons.Comment: 16 pages and two figures, uses eps
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