5,174 research outputs found
ZZE-Configuration of chromophore ß-153 in C-phycocyanin from Mastigocladus laminosus
The photochemistry of C-phycocyanin has been studied after denaturation in the dark. It shows
an irreversible reaction which has characteristics of a Ζ,Ζ,Ε- to Z,Z,Z-isomerization of dihydrobilins.
Its amplitude depends on the reaction conditions, with a maximum corresponding to 15%
conversion of one of the three PC chromophores. This chromophore is suggested to be ß-153, for
which recent X-ray data T. Schirmer, W. Bode, and R. Huber, J. Mol. Biol., submitted, show
ring D being highly twisted out of the plane of the other rings. During unfolding, there is thus a
probability of falling into the photochemically labile Z,Z,^-configuration
Effect of aggregation on chromophore structure in allophycocyanin studied by resonance CARS-spectroscopy
Field theoretic formulation of a mode-coupling equation for colloids
The only available quantitative description of the slowing down of the
dynamics upon approaching the glass transition has been, so far, the
mode-coupling theory, developed in the 80's by G\"otze and collaborators. The
standard derivation of this theory does not result from a systematic expansion.
We present a field theoretic formulation that arrives at very similar
mode-coupling equation but which is based on a variational principle and on a
controlled expansion in a small dimensioneless parameter. Our approach applies
to such physical systems as colloids interacting via a mildly repulsive
potential. It can in principle, with moderate efforts, be extended to higher
orders and to multipoint correlation functions
Relative multiplexing for minimizing switching in linear-optical quantum computing
Many existing schemes for linear-optical quantum computing (LOQC) depend on
multiplexing (MUX), which uses dynamic routing to enable near-deterministic
gates and sources to be constructed using heralded, probabilistic primitives.
MUXing accounts for the overwhelming majority of active switching demands in
current LOQC architectures. In this manuscript, we introduce relative
multiplexing (RMUX), a general-purpose optimization which can dramatically
reduce the active switching requirements for MUX in LOQC, and thereby reduce
hardware complexity and energy consumption, as well as relaxing demands on
performance for various photonic components. We discuss the application of RMUX
to the generation of entangled states from probabilistic single-photon sources,
and argue that an order of magnitude improvement in the rate of generation of
Bell states can be achieved. In addition, we apply RMUX to the proposal for
percolation of a 3D cluster state in [PRL 115, 020502 (2015)], and we find that
RMUX allows a 2.4x increase in loss tolerance for this architecture.Comment: Published version, New Journal of Physics, Volume 19, June 201
Evolution of smart devices and human movement apps: Recommendations for use in sports science education and practice
Many smart phones and tablets possess high-speed cameras. An increasing number of human movement professionals (e.g. personal trainers, athletics coaches, strength and conditioning coaches and physiotherapists) are beginning to use human movement analysis apps with their smart phones/tablets to quantitatively assess their clients’ performance and injury risk. However, an understanding of the validity and reliability of these tools is required. This narrative review seeks to list some relevant human movement apps; summarise the validity and reliability of selected apps and to provide recommendations for their use ineducation and practice
Noncommutative Effects in the Black Hole Evaporation in Two Dimensions
We discuss some possible implications of a two-dimensional toy model for
black hole evaporation in noncommutative field theory. While the
noncommutativity we consider does not affect gravity, it can play an important
role in the dynamics of massless and Hermitian scalar fields in the event
horizon of a Schwarzschild black hole. We find that noncommutativity will
affect the flux of outgoing particles and the nature of its UV/IR divergences.
Moreover, we show that the noncommutative interaction does not affect Leahy's
and Unruh's interpretation of thermal ingoing and outgoing fluxes in the black
hole evaporation process. Thus, the noncommutative interaction still destroys
the thermal nature of fluxes. In the process, some nonlocal implications of the
noncommutativity are discussed.Comment: 33+1 pages, 3 eps figures, typos corrected, references added, figure
3 corrected, modifications in sections 4 and 6, version published in Phys.
Rev.
Two independent photon pairs versus four-photon entangled states in parametric down conversion
We study the physics of four-photon states generated in spontaneous
parametric down-conversion with a pulsed pump field. In the limit where the
coherence time of the photons t_c is much shorter than the duration of the pump
pulse Delta t, the four photons can be described as two independent pairs. In
the opposite limit, the four photons are in a four-particle entangled state.
Any intermediate case can be characterized by a single parameter chi, which is
a function of t_c/Delta t. We present a direct measurement of chi through a
simple experimental setup. The full theoretical analysis is also provided.Comment: 10 pages, 3 figures, submitte
Self-Dual Action for Fermionic Fields and Gravitation
This paper studies the self-dual Einstein-Dirac theory. A generalization is
obtained of the Jacobson-Smolin proof of the equivalence between the self-dual
and Palatini purely gravitational actions. Hence one proves equivalence of
self-dual Einstein-Dirac theory to the Einstein-Cartan-Sciama-Kibble-Dirac
theory. The Bianchi symmetry of the curvature, core of the proof, now contains
a non-vanishing torsion. Thus, in the self-dual framework, the extra terms
entering the equations of motion with respect to the standard Einstein-Dirac
field equations, are neatly associated with torsion.Comment: 13 pages, plain-tex, recently appearing in Nuovo Cimento B, volume
109, pages 973-982, September 199
‘Opportunities have pretty much disappeared’:the movement for Scottish Independence in abeyance during COVID-19
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