2,909 research outputs found
Non-Local Matrix Generalizations of W-Algebras
There is a standard way to define two symplectic (hamiltonian) structures,
the first and second Gelfand-Dikii brackets, on the space of ordinary linear
differential operators of order , . In this paper, I consider in detail the case where the are
-matrix-valued functions, with particular emphasis on the (more
interesting) second Gelfand-Dikii bracket. Of particular interest is the
reduction to the symplectic submanifold . This reduction gives rise to
matrix generalizations of (the classical version of) the {\it non-linear}
-algebras, called -algebras. The non-commutativity of the
matrices leads to {\it non-local} terms in these -algebras. I show
that these algebras contain a conformal Virasoro subalgebra and that
combinations of the can be formed that are -matrices of
conformally primary fields of spin , in analogy with the scalar case .
In general however, the -algebras have a much richer structure than
the -algebras as can be seen on the examples of the {\it non-linear} and
{\it non-local} Poisson brackets of any two matrix elements of or
which I work out explicitly for all and . A matrix Miura transformation
is derived, mapping these complicated second Gelfand-Dikii brackets of the
to a set of much simpler Poisson brackets, providing the analogue of the
free-field realization of the -algebras.Comment: 43 pages, a reference and a remark on the conformal properties for
adde
KCNQ channels regulate age-related memory impairment:KCNQ regulates age-related memory
In humans KCNQ2/3 heteromeric channels form an M-current that acts as a brake on neuronal excitability, with mutations causing a form of epilepsy. The M-current has been shown to be a key regulator of neuronal plasticity underlying associative memory and ethanol response in mammals. Previous work has shown that many of the molecules and plasticity mechanisms underlying changes in alcohol behaviour and addiction are shared with those of memory. We show that the single KCNQ channel in Drosophila (dKCNQ) when mutated show decrements in associative short- and long-term memory, with KCNQ function in the mushroom body α/ÎČneurons being required for short-term memory. Ethanol disrupts memory in wildtype flies, but not in a KCNQ null mutant background suggesting KCNQ maybe a direct target of ethanol, the blockade of which interferes with the plasticity machinery required for memory formation. We show that as in humans, Drosophila display age-related memory impairment with the KCNQ mutant memory defect mimicking the effect of age on memory. Expression of KCNQ normally decreases in aging brains and KCNQ overexpression in the mushroom body neurons of KCNQ mutants restores age-related memory impairment. Therefore KCNQ is a central plasticity molecule that regulates age dependent memory impairment
Multi-Component KdV Hierarchy, V-Algebra and Non-Abelian Toda Theory
I prove the recently conjectured relation between the -matrix
differential operator , and a certain non-linear and non-local
Poisson bracket algebra (-algebra), containing a Virasoro subalgebra, which
appeared in the study of a non-abelian Toda field theory. Here, I show that
this -algebra is precisely given by the second Gelfand-Dikii bracket
associated with . The Miura transformation is given which relates the second
to the first Gelfand-Dikii bracket. The two Gelfand-Dikii brackets are also
obtained from the associated (integro-) differential equation satisfied by
fermion bilinears. The asymptotic expansion of the resolvent of
is studied and its coefficients yield an infinite sequence of
hamiltonians with mutually vanishing Poisson brackets. I recall how this leads
to a matrix KdV hierarchy which are flow equations for the three component
fields of . For they reduce to the ordinary KdV
hierarchy. The corresponding matrix mKdV equations are also given, as well as
the relation to the pseudo- differential operator approach. Most of the results
continue to hold if is a hermitian -matrix. Conjectures are made
about -matrix -order differential operators and
associated -algebras.Comment: 20 pages, revised: several references to earlier papers on
multi-component KdV equations are adde
Classical A_n--W-Geometry
This is a detailed development for the case, of our previous article
entitled "W-Geometries" to be published in Phys. Lett. It is shown that the
--W-geometry corresponds to chiral surfaces in . This is comes out
by discussing 1) the extrinsic geometries of chiral surfaces (Frenet-Serret and
Gauss-Codazzi equations) 2) the KP coordinates (W-parametrizations) of the
target-manifold, and their fermionic (tau-function) description, 3) the
intrinsic geometries of the associated chiral surfaces in the Grassmannians,
and the associated higher instanton- numbers of W-surfaces. For regular points,
the Frenet-Serret equations for --W-surfaces are shown to give the
geometrical meaning of the -Toda Lax pair, and of the conformally-reduced
WZNW models, and Drinfeld-Sokolov equations. KP coordinates are used to show
that W-transformations may be extended as particular diffeomorphisms of the
target-space. This leads to higher-dimensional generalizations of the WZNW and
DS equations. These are related with the Zakharov- Shabat equations. For
singular points, global Pl\"ucker formulae are derived by combining the
-Toda equations with the Gauss-Bonnet theorem written for each of the
associated surfaces.Comment: (60 pages
Rational vs Polynomial Character of W-Algebras
The constraints proposed recently by Bershadsky to produce algebras
are a mixture of first and second class constraints and are degenerate. We show
that they admit a first-class subsystem from which they can be recovered by
gauge-fixing, and that the non-degenerate constraints can be handled by
previous methods. The degenerate constraints present a new situation in which
the natural primary field basis for the gauge-invariants is rational rather
than polynomial. We give an algorithm for constructing the rational basis and
converting the base elements to polynomials.Comment: 18 page
Enhancing pharmaceutical packaging through a technology ecosystem to facilitate the reuse of medicines and reduce medicinal waste
The idea of reusing dispensed medicines is appealing to the general public provided its benefits are illustrated, its risks minimized, and the logistics resolved. For example, medicine reuse could help reduce medicinal waste, protect the environment and improve public health. However, the associated technologies and legislation facilitating medicine reuse are generally not available. The availability of suitable technologies could arguably help shape stakeholdersâ beliefs and in turn, uptake of a future medicine reuse scheme by tackling the risks and facilitating the practicalities. A literature survey is undertaken to lay down the groundwork for implementing technologies on and around pharmaceutical packaging in order to meet stakeholdersâ previously expressed misgivings about medicine reuse (âstakeholder requirementsâ), and propose a novel ecosystem for, in effect, reusing returned medicines. Methods: A structured literature search examining the application of existing technologies on pharmaceutical packaging to enable medicine reuse was conducted and presented as a narrative review. Results: Reviewed technologies are classified according to different stakeholdersâ requirements, and a novel ecosystem from a technology perspective is suggested as a solution to reusing medicines. Conclusion: Active sensing technologies applying to pharmaceutical packaging using printed electronics enlist medicines to be part of the Internet of Things network. Validating the quality and safety of returned medicines through this network seems to be the most effective way for reusing medicines and the correct application of technologies may be the key enabler
Islam in Turkish Cinema
This essay describes the history of Turkish cinema from its origins in 1896 until the present, focusing upon how Islam and religious Muslims are portrayed in the movies. For historical, political, and cultural reasons, Islam and religious Muslims have often been portrayed in a negative light, even though Turkey is a predominantly Muslim country. Present day Turkish cinema offers a more eclectic array of movies, including movies that show Islamic practices in daily life and movies that portray Islam in a favorable light
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