3,475 research outputs found
On the Geometry of the Moduli Space of Real Binary Octics
The moduli space of smooth real binary octics has five connected components.
They parametrize the real binary octics whose defining equations have 0, 1,
..., 4 complex-conjugate pairs of roots respectively. We show that the
GIT-stable completion of each of these five components admits the structure of
an arithmetic real hyperbolic orbifold. The corresponding monodromy groups are,
up to commensurability, discrete hyperbolic reflection groups, and their
Vinberg diagrams are computed. We conclude with a simple proof that the moduli
space of GIT-stable real binary octics itself cannot be a real hyperbolic
orbifold.Comment: 23 page
Scaling of stiffness energy for 3d +/-J Ising spin glasses
Large numbers of ground states of 3d EA Ising spin glasses are calculated for
sizes up to 10^3 using a combination of a genetic algorithm and Cluster-Exact
Approximation. A detailed analysis shows that true ground states are obtained.
The ground state stiffness (or domain wall) energy D is calculated. A D ~ L^t
behavior with t=0.19(2) is found which strongly indicates that the 3d model has
an equilibrium spin-glass-paramagnet transition for non-zero T_c.Comment: 4 pages, 4 figure
A new method for analyzing ground-state landscapes: ballistic search
A ``ballistic-search'' algorithm is presented which allows the identification
of clusters (or funnels) of ground states in Ising spin glasses even for
moderate system sizes. The clusters are defined to be sets of states, which are
connected in state-space by chains of zero-energy flips of spins. The technique
can also be used to estimate the sizes of such clusters. The performance of the
method is tested with respect to different system sizes and choices of
parameters. As an application the ground-state funnel structure of
two-dimensional +or- J spin glasses of systems up to size L=20 is analyzed by
calculating a huge number of ground states per realization. A T=0 entropy per
spin of s_0=0.086(4)k_B is obtained.Comment: 10 pages, 11 figures, 35 references, revte
Ordered phase in the two-dimensional randomly coupled ferromagnet
True ground states are evaluated for a 2d Ising model with random near
neighbor interactions and ferromagnetic second neighbor interactions (the
Randomly Coupled Ferromagnet). The spin glass stiffness exponent is positive
when the absolute value of the random interaction is weaker than the
ferromagnetic interaction. This result demonstrates that in this parameter
domain the spin glass like ordering temperature is non-zero for these systems,
in strong contrast to the 2d Edwards-Anderson spin glass.Comment: 7 pages; 9 figures; revtex; new version much extende
A game-based corpus for analysing the interplay between game context and player experience
Recognizing players’ affective state while playing video games has been the focus of many recent research studies. In this paper we describe the process that has been followed to build a corpus based on game events and recorded video sessions from human players while playing Super Mario Bros. We present different types of information that have been extracted from game context, player preferences and perception of the game, as well as user features, automatically extracted from video recordings. We run a number of initial experiments to analyse players’ behavior while playing video games as a case study of the possible use of the corpus.peer-reviewe
Specific-Heat Exponent of Random-Field Systems via Ground-State Calculations
Exact ground states of three-dimensional random field Ising magnets (RFIM)
with Gaussian distribution of the disorder are calculated using
graph-theoretical algorithms. Systems for different strengths h of the random
fields and sizes up to N=96^3 are considered. By numerically differentiating
the bond-energy with respect to h a specific-heat like quantity is obtained,
which does not appear to diverge at the critical point but rather exhibits a
cusp. We also consider the effect of a small uniform magnetic field, which
allows us to calculate the T=0 susceptibility. From a finite-size scaling
analysis, we obtain the critical exponents \nu=1.32(7), \alpha=-0.63(7),
\eta=0.50(3) and find that the critical strength of the random field is
h_c=2.28(1). We discuss the significance of the result that \alpha appears to
be strongly negative.Comment: 9 pages, 9 figures, 1 table, revtex revised version, slightly
extende
The modular geometry of Random Regge Triangulations
We show that the introduction of triangulations with variable connectivity
and fluctuating egde-lengths (Random Regge Triangulations) allows for a
relatively simple and direct analyisis of the modular properties of 2
dimensional simplicial quantum gravity. In particular, we discuss in detail an
explicit bijection between the space of possible random Regge triangulations
(of given genus g and with N vertices) and a suitable decorated version of the
(compactified) moduli space of genus g Riemann surfaces with N punctures. Such
an analysis allows us to associate a Weil-Petersson metric with the set of
random Regge triangulations and prove that the corresponding volume provides
the dynamical triangulation partition function for pure gravity.Comment: 36 pages corrected typos, enhanced introductio
Ground-state behavior of the 3d +/-J random-bond Ising model
Large numbers of ground states of the three-dimensional random-bond
Ising model are calculated for sizes up to using a combination of a
genetic algorithm and Cluster-Exact Approximation. Several quantities are
calculated as function of the concentration of the antiferromagnetic bonds.
The critical concentration where the ferromagnetic order disappears is
determined using the Binder cumulant of the magnetization. A value of
is obtained. From the finite-size behavior of the Binder
cumulant and the magnetization critical exponents and
are calculated.Comment: 8 pages, 11 figures, revte
Characterization of the contactin 5 protein and its risk-associated polymorphic variant throughout the Alzheimer's disease spectrum
INTRODUCTION:
We investigate the CNTN5 rs1461684 G variant and the contactin 5 protein in sporadic Alzheimer's disease (sAD).
METHODS:
Contactin 5, sAD biomarkers, and synaptic markers were measured in the cerebrospinal fluid (CSF). Amyloid and tau deposition were assessed using positron emission tomography. Contactin 5 protein and mRNA levels were measured in brain tissue.
RESULTS:
CSF contactin 5 increases progressively in cognitively unimpaired individuals and is decreased in mild cognitive impairment and sAD. CSF contactin 5 correlates with sAD biomarkers and with synaptic markers. The rs1461684 G variant associates with faster disease progression in cognitively unimpaired subjects. Cortical full-length and isoform 3 CNTN5 mRNAs are decreased in the presence of the G allele and as a function of Consortium to Establish a Registry for Alzheimer's Disease stages.
DISCUSSION:
The newly identified rs1461684 G variant associates with sAD risk, rate of disease progression, and gene expression. Contactin 5 protein and mRNA are affected particularly in the early stages of the diseas
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