474 research outputs found
Characteristic Time and Maximum Mixedness: Single Mode Gaussian States in Dissipative Channels
We derive an upper limit for the mixedness of single bosonic mode gaussian
states propagating in dissipative channels. It is a function of the initial
squeezing and temperature of the channel only. Moreover the time at which von
Neumann's entropy reaches its maximum value coincides with that of complete
loss of coherence, thus defining a quantum-classical transition.Comment: Accepted versio
Peptide mimics selected from immune sera using phage display technology can replace native antigens in the diagnosis of Epstein–Barr virus infection
There is an expanding area of small molecule discovery, especially in the area of peptide mimetics. Peptide sequences can be used to substitute for the entire native antigen for use in diagnostic assays. Our approach is to select peptides that mimic epitopes of the natural immune response to Epstein–Barr virus (EBV) that may be recognised by antibodies typically produced after infection with EBV. We screened a random peptide library on sera from rabbits immunised with a crude preparation of EBV and serum antibodies from a patient with a high titer of EBV antibodies. We selected four peptides (Eb1–4) with the highest relative binding affinity with immune rabbit sera and a single peptide with high affinity to human serum antibodies. The peptides were coupled to the carrier molecule BSA and the recognition of the peptides by IgM antibodies in clinical samples after infection with EBV was measured. The sensitivities were Eb1 94%, Eb2, 3, 4 88%, H1 81% and all had 100% specificity. This study illustrates that the phage display approach to select epitope mimics can be applied to polyclonal antibodies and peptides that represent several diagnostically important epitopes can be selected simultaneously. This panel of EBV peptides representing a wide coverage of immunodominant epitopes could replace crude antigen preparations currently used for capture in commercial diagnostic tests for EBV
reaction at intermediate energies
The reaction is considered at the energies between 200 MeV and
520 MeV. The Alt-Grassberger-Sandhas equations are iterated up to the lowest
order terms over the nucleon-nucleon t-matrix. The parameterized wave
function including five components is used. The angular dependence of the
differential cross section and energy dependence of tensor analyzing power
at the zero scattering angle are presented in comparison with the
experimental data
Electromagnetic waves in a wormhole geometry
We investigate the propagation of electromagnetic waves through a static
wormhole. It is shown that the problem can be reduced to a one-dimensional
Schr\"odinger-like equation with a barrier-type potential. Using numerical
methods, we calculate the transmission coefficient as a function of the energy.
We also discuss the polarization of the outgoing radiation due to this
gravitational scattering.Comment: LaTex file, 5 pages, 2 figures, one reference added, accepted for
publication in PR
Quantum Inequalities for the Electromagnetic Field
A quantum inequality for the quantized electromagnetic field is developed for
observers in static curved spacetimes. The quantum inequality derived is a
generalized expression given by a mode function expansion of the four-vector
potential, and the sampling function used to weight the energy integrals is
left arbitrary up to the constraints that it be a positive, continuous function
of unit area and that it decays at infinity. Examples of the quantum inequality
are developed for Minkowski spacetime, Rindler spacetime and the Einstein
closed universe.Comment: 19 pages, 1 table and 1 figure. RevTex styl
Particle decays and stability on the de Sitter universe
We study particle decay in de Sitter space-time as given by first order
perturbation theory in a Lagrangian interacting quantum field theory. We study
in detail the adiabatic limit of the perturbative amplitude and compute the
"phase space" coefficient exactly in the case of two equal particles produced
in the disintegration. We show that for fields with masses above a critical
mass there is no such thing as particle stability, so that decays
forbidden in flat space-time do occur here. The lifetime of such a particle
also turns out to be independent of its velocity when that lifetime is
comparable with de Sitter radius. Particles with mass lower than critical have
a completely different behavior: the masses of their decay products must obey
quantification rules, and their lifetime is zero.Comment: Latex, 38 pages, 1 PostScript figure; added references, minor
corrections and remark
Heating rate and electrode charging measurements in a scalable, microfabricated, surface-electrode ion trap
We characterise the performance of a surface-electrode ion "chip" trap
fabricated using established semiconductor integrated circuit and
micro-electro-mechanical-system (MEMS) microfabrication processes which are in
principle scalable to much larger ion trap arrays, as proposed for implementing
ion trap quantum information processing. We measure rf ion micromotion parallel
and perpendicular to the plane of the trap electrodes, and find that on-package
capacitors reduce this to <~ 10 nm in amplitude. We also measure ion trapping
lifetime, charging effects due to laser light incident on the trap electrodes,
and the heating rate for a single trapped ion. The performance of this trap is
found to be comparable with others of the same size scale.Comment: 6 pages, 10 figure
Dynamic Scaling and Two-Dimensional High-Tc Superconductors
There has been ongoing debate over the critical behavior of two-dimensional
superconductors; in particular for high Tc superconductors. The conventional
view is that a Kosterlitz-Thouless-Berezinskii transition occurs as long as
finite size effects do not obscure the transition. However, there have been
recent suggestions that a different transition actually occurs which
incorporates aspects of both the dynamic scaling theory of Fisher, Fisher, and
Huse and the Kosterlitz-Thouless-Berezinskii transition. Of general interest is
that this modified transition apparently has a universal dynamic critical
exponent. Some have countered that this apparent universal behavior is rooted
in a newly proposed finite-size scaling theory; one that also incorporates
scaling and conventional two-dimensional theory. To investigate these issues we
study DC voltage versus current data of a 12 angstrom thick YBCO film. We find
that the newly proposed scaling theories have intrinsic flexibility that is
relevant to the analysis of the experiments. In particular, the data scale
according to the modified transition for arbitrarily defined critical
temperatures between 0 K and 19.5 K, and the temperature range of a successful
scaling collapse is related directly to the sensitivity of the measurement.
This implies that the apparent universal exponent is due to the intrinsic
flexibility rather than some real physical property. To address this intrinsic
flexibility, we propose a criterion which would give conclusive evidence for
phase transitions in two-dimensional superconductors. We conclude by reviewing
results to see if our criterion is satisfied.Comment: 14 page
The Green Bank Telescope 350 MHz Drift-scan Survey II:Data Analysis and the Timing of 10 New Pulsars, Including a Relativistic Binary
Deconstructing the financialization of healthcare
Financialization is promoted by alliances of multilateral 'development' organisations, national governments, and owners and institutions of private capital. In the healthcare sector, the leveraging of private sources of finance is widely argued as necessary to achieve the Sustainable Development Goal 3 target of universal health coverage. Employing social science perspectives on financialization, we contend that this is a new phase of capital formation. We trace the antecedents, institutions, instruments and ideas that facilitated the penetration of private capital in this sector, and the emergence of new asset classes that distinguish it. We argue that this deepening of financialization represents a fundamental shift in the organizing principles for healthcare systems, with negative implications for health and equality
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