1,059 research outputs found
Three fermions with six single particle states can be entangled in two inequivalent ways
Using a generalization of Cayley's hyperdeterminant as a new measure of
tripartite fermionic entanglement we obtain the SLOCC classification of
three-fermion systems with six single particle states. A special subclass of
such three-fermion systems is shown to have the same properties as the
well-known three-qubit ones. Our results can be presented in a unified way
using Freudenthal triple systems based on cubic Jordan algebras. For systems
with an arbitrary number of fermions and single particle states we propose the
Pl\"ucker relations as a sufficient and necessary condition of separability.Comment: 23 pages LATE
'A landmark in psychiatric progress'? The role of evidence in the rise and fall of insulin coma therapy
This paper examines the evidence behind the use and decline of insulin coma therapy as a treatment for schizophrenia and how this was viewed by the psychiatric profession. The paper demonstrates that, from the time of its introduction, there was considerable debate regarding the evidence for insulin treatment, and scepticism about its purported benefits. The randomized trials conducted in the 1950s were the result, rather than the origins, of this debate. Although insulin treatment was subsequently abandoned, it was still regarded as a historic moment in the modernization of psychiatry. Then, as now, evidence does not speak for itself, and insulin continued to be incorporated into the story of psychiatric progress even after it was shown to be ineffective
Process studies in the hydro- and geosphere of the tropical/subtropical North Atlantic Cruise No. 04 December 03, – April 03, 2006/2007, Fort de France (Martinique) – Las Palmas (Spain)
Linking working memory and long-term memory: A computational model of the learning of new words
The nonword repetition (NWR) test has been shown to be a good predictor of children’s vocabulary size. NWR performance has been explained using phonological working memory, which is seen as a critical component in the learning of new words. However, no detailed specification of the link between phonological working memory and long-term memory (LTM) has been proposed. In this paper, we present a computational model of children’s vocabulary acquisition (EPAM-VOC) that specifies how phonological working memory and LTM interact. The model learns phoneme sequences, which are stored in LTM and mediate how much information can be held in working memory. The model’s behaviour is compared with that of children in a new study of NWR, conducted in order to ensure the same nonword stimuli and methodology across ages. EPAM-VOC shows a pattern of results similar to that of children: performance is better for shorter nonwords and for wordlike nonwords, and performance improves with age. EPAM-VOC also simulates the superior performance for single consonant nonwords over clustered consonant nonwords found in previous NWR studies. EPAM-VOC provides a simple and elegant computational account of some of the key processes involved in the learning of new words: it specifies how phonological working memory and LTM interact; makes testable predictions; and suggests that developmental changes in NWR performance may reflect differences in the amount of information that has been encoded in LTM rather than developmental changes in working memory capacity.
Keywords: EPAM, working memory, long-term memory, nonword repetition, vocabulary acquisition, developmental change
A formula for the First Eigenvalue of the Dirac Operator on Compact Spin Symmetric Spaces
Let be a simply connected spin compact inner irreducible symmetric
space, endowed with the metric induced by the Killing form of sign-changed.
We give a formula for the square of the first eigenvalue of the Dirac operator
in terms of a root system of . As an example of application, we give the
list of the first eigenvalues for the spin compact irreducible symmetric spaces
endowed with a quaternion-K\"{a}hler structure
Magic Supergravities, N= 8 and Black Hole Composites
We present explicit U-duality invariants for the R, C, Q, O$ (real, complex,
quaternionic and octonionic) magic supergravities in four and five dimensions
using complex forms with a reality condition. From these invariants we derive
an explicit entropy function and corresponding stabilization equations which we
use to exhibit stationary multi-center 1/2 BPS solutions of these N=2 d=4
theories, starting with the octonionic one with E_{7(-25)} duality symmetry. We
generalize to stationary 1/8 BPS multicenter solutions of N=8, d=4
supergravity, using the consistent truncation to the quaternionic magic N=2
supergravity. We present a general solution of non-BPS attractor equations of
the STU truncation of magic models. We finish with a discussion of the
BPS-non-BPS relations and attractors in N=2 versus N= 5, 6, 8.Comment: 33 pages, references added plus brief outline at end of introductio
Geometric scaling in high-energy QCD at nonzero momentum transfer
We show how one can obtain geometric scaling properties from the
Balitsky-Kovchegov (BK) equation. We start by explaining how, this property
arises for the b-independent BK equation. We show that it is possible to extend
this model to the full BK equation including momentum transfer. The saturation
scale behaves like max(q,Q_T) where q is the momentum transfer and Q_T a
typical scale of the target.Comment: 4 pages, 2 figures. Talk given by G. Soyez at the "Rencontres de
Moriond", 12-19 March 2005, La Thuile, Ital
Common Representation of Information Flows for Dynamic Coalitions
We propose a formal foundation for reasoning about access control policies
within a Dynamic Coalition, defining an abstraction over existing access
control models and providing mechanisms for translation of those models into
information-flow domain. The abstracted information-flow domain model, called a
Common Representation, can then be used for defining a way to control the
evolution of Dynamic Coalitions with respect to information flow
Fundamental Weights, Permutation Weights and Weyl Character Formula
For a finite Lie algebra of rank N, the Weyl orbits
of strictly dominant weights contain number of
weights where is the dimension of its Weyl group . For any
, there is a very peculiar subset for
which we always have For
any dominant weight , the elements of are called
{\bf Permutation Weights}.
It is shown that there is a one-to-one correspondence between elements of
and where is the Weyl vector of .
The concept of signature factor which enters in Weyl character formula can be
relaxed in such a way that signatures are preserved under this one-to-one
correspondence in the sense that corresponding permutation weights have the
same signature. Once the permutation weights and their signatures are specified
for a dominant , calculation of the character for
irreducible representation will then be provided by
multiplicity rules governing generalized Schur functions. The main idea is
again to express everything in terms of the so-called {\bf Fundamental Weights}
with which we obtain a quite relevant specialization in applications of Weyl
character formula.Comment: 6 pages, no figures, TeX, as will appear in Journal of Physics
A:Mathematical and Genera
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