3,878 research outputs found
Coding of the Reach Vector in Parietal Area 5d
Competing models of sensorimotor computation predict different topological constraints in the brain. Some models propose population coding of particular reference frames in anatomically distinct nodes, whereas others require no such dedicated subpopulations and instead predict that regions will simultaneously code in multiple, intermediate, reference frames. Current empirical evidence is conflicting, partly due to difficulties involved in identifying underlying reference frames. Here, we independently varied the locations of hand, gaze, and target over many positions while recording from the dorsal aspect of parietal area 5. We find that the target is represented in a predominantly hand-centered reference frame here, contrasting with the relative code seen in dorsal premotor cortex and the mostly gaze-centered reference frame in the parietal reach region. This supports the hypothesis that different nodes of the sensorimotor circuit contain distinct and systematic representations, and this constrains the types of computational model that are neurobiologically relevant
Alternating quaternary algebra structures on irreducible representations of sl(2,C)
We determine the multiplicity of the irreducible representation V(n) of the
simple Lie algebra sl(2,C) as a direct summand of its fourth exterior power
. The multiplicity is 1 (resp. 2) if and only if n = 4, 6
(resp. n = 8, 10). For these n we determine the multilinear polynomial
identities of degree satisfied by the sl(2,C)-invariant alternating
quaternary algebra structures obtained from the projections . We represent the polynomial identities as the nullspace of a large
integer matrix and use computational linear algebra to find the canonical basis
of the nullspace.Comment: 26 pages, 13 table
Quantum Sampling Problems, BosonSampling and Quantum Supremacy
There is a large body of evidence for the potential of greater computational
power using information carriers that are quantum mechanical over those
governed by the laws of classical mechanics. But the question of the exact
nature of the power contributed by quantum mechanics remains only partially
answered. Furthermore, there exists doubt over the practicality of achieving a
large enough quantum computation that definitively demonstrates quantum
supremacy. Recently the study of computational problems that produce samples
from probability distributions has added to both our understanding of the power
of quantum algorithms and lowered the requirements for demonstration of fast
quantum algorithms. The proposed quantum sampling problems do not require a
quantum computer capable of universal operations and also permit physically
realistic errors in their operation. This is an encouraging step towards an
experimental demonstration of quantum algorithmic supremacy. In this paper, we
will review sampling problems and the arguments that have been used to deduce
when sampling problems are hard for classical computers to simulate. Two
classes of quantum sampling problems that demonstrate the supremacy of quantum
algorithms are BosonSampling and IQP Sampling. We will present the details of
these classes and recent experimental progress towards demonstrating quantum
supremacy in BosonSampling.Comment: Survey paper first submitted for publication in October 2016. 10
pages, 4 figures, 1 tabl
Simultaneous Arithmetic Progressions on Algebraic Curves
A simultaneous arithmetic progression (s.a.p.) of length k consists of k
points (x_i, y_\sigma(i)), where x_i and y_i are arithmetic progressions and
\sigma is a permutation. Garcia-Selfa and Tornero asked whether there is a
bound on the length of an s.a.p. on an elliptic curve in Weierstrass form over
Q. We show that 4319 is such a bound for curves over R. This is done by
considering translates of the curve in a grid as a graph. A simple upper bound
is found for the number of crossings and the 'crossing inequality' gives a
lower bound. Together these bound the length of an s.a.p. on the curve. We then
use a similar method to extend the result to arbitrary real algebraic curves.
Instead of considering s.a.p.'s we consider k^2/3 points in a grid. The number
of crossings is bounded by Bezout's Theorem. We then give another proof using a
result of Jarnik bounding the number of grid points on a convex curve. This
result applies as any real algebraic curve can be broken up into convex and
concave parts, the number of which depend on the degree. Lastly, these results
are extended to complex algebraic curves.Comment: 11 pages, 6 figures, order of email addresses corrected 12 pages,
closing remarks, a reference and an acknowledgment adde
A patient preference study that evaluated fluticasone furoate and mometasone furoate nasal sprays for allergic rhinitis
Background: Corticosteroid nasal sprays are the mainstay of treatment for allergic rhinitis. These sprays have sensory attributes such as scent and/or odor, taste and aftertaste, and run down the throat and/or the nose, which, when unpleasant, can affect patient preference for, and compliance with, treatment.
Objective: This study examined patient preference for fluticasone furoate nasal spray (FFNS) or mometasone furoate nasal spray (MFNS) based on their sensory attributes after administration in patients with allergic rhinitis.
Methods: This was a multicenter, randomized, double-blind, cross-over study. Patient preferences were determined by using three questionnaires (Overall Preference, Immediate Attributes, and Delayed Attributes).
Results: Overall, 56% of patients stated a preference for FFNS versus 32% for MFNS (p _ 0.001); the remaining 12% stated no preference. More patients stated a preference for FFNS versus MFNS for the attributes of “less drip down the throat” (p _ 0.001), “less run out of the nose” (p _ 0.05), “more soothing” (p _ 0.05), and “less irritating” (p _ 0.001). More patients responded in favor of FFNS versus MFNS for the immediate attributes, “run down the throat” (p _ 0.001), and “run out of the nose” (p _ 0.001), and, in the delayed attributes, “run down the throat” (p _ 0.001), “run out of the nose” (p _ 0.01), “presence of aftertaste” (p _ 0.01), and “no nasal irritation” (p _ 0.001).
Conclusion: Patients with allergic rhinitis preferred FFNS versus MFNS overall and based on a number of individual attributes, including “less drip down the throat,” “less run out of the nose,” and “less irritating.” Greater preference may improve patient adherence and thereby improve symptom management of the patient’s allergic rhinitis
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