16,295 research outputs found

### Small deviations for beta ensembles

We establish various small deviation inequalities for the extremal (soft
edge) eigenvalues in the beta-Hermite and beta-Laguerre ensembles. In both
settings, upper bounds on the variance of the largest eigenvalue of the
anticipated order follow immediately

### Metallicity as a criterion to select H2 bearing Damped Lyman-alpha systems

We characterize the importance of metallicity on the presence of molecular
hydrogen in damped Lyman-alpha (DLA) systems. We construct a representative
sample of 18 DLA/sub-DLA systems with log N(HI)>19.5 at high redshift
(zabs>1.8) with metallicities relative to solar [X/H]>-1.3(with[X/H]=
logN(X)/N(H)-log(X/H)solar and X either Zn, S or Si). We gather data covering
the expected wavelength range of redshifted H2 absorption lines on all systems
in the sample from either the literature (10 DLAs), the UVES-archive or new
VLT-UVES observations for four of them. The sample is large enough to discuss
for the first time the importance of metallicity as a criterion for the
presence of molecular hydrogen in the neutral phase at high-z. From the new
observations, we report two new detections of molecular hydrogen in the systems
at zabs=2.431 toward Q2343+125 and zabs=2.426 toward Q2348-011. We compare the
H2 detection fraction in the high-metallicity sample with the detection
fraction in the overall sample from Ledoux et al. (2003). We show that the
fraction of DLA systems with logf=log 2N(H2)/(2N(H2)+N(HI))>-4 is as large as
50% for [X/H]>-0.7 when it is only about 5% for [X/H]<-1.3 and about 15% in the
overall sample (with -2.5<[X/H]<-0.3). This demonstrates that the presence of
molecular hydrogen at high redshift is strongly correlated with metallicity.Comment: 4 pages, 3 Postscript figures. Accepted in Astronomy and Astrophysics
Lette

### Spectral analysis of Markov kernels and application to the convergence rate of discrete random walks

Let $\{X_n\}_{n\in\N}$ be a Markov chain on a measurable space \X with
transition kernel $P$ and let V:\X\r[1,+\infty). The Markov kernel $P$ is
here considered as a linear bounded operator on the weighted-supremum space
\cB_V associated with $V$. Then the combination of quasi-compactness
arguments with precise analysis of eigen-elements of $P$ allows us to estimate
the geometric rate of convergence $\rho_V(P)$ of $\{X_n\}_{n\in\N}$ to its
invariant probability measure in operator norm on \cB_V. A general procedure
to compute $\rho_V(P)$ for discrete Markov random walks with identically
distributed bounded increments is specified

### Higher-Order Memory Schema and Conscious Experience

In the interesting and thought-provoking article Grazziano and colleagues argue for their Attention Schema Theory (AST) of consciousness. They present AST as a unification of Global Workspace Theory (GWT), Illusionism, and the Higher-Order Thought (HOT) theory. We argue it is a mistake to equate 'subjective experience,' ad related terms, with dualism. They simply denote experience. Also, as presented, AST does not accurately capture the essence of HOT for two reasons. HOT is presented as a version of strong illusionism, which it isn't, and HOT requires that one be aware of one's mental life, and postulates that his consists in a re-representation of what is occurring at at the lower-order levels. However, the authors deny that AST involves re-representing visual stimuli. We close by proposing an alternative unification: GWT and AST provide crucial accounts of how lower-order states are assembled and maintained, but higher-order theory provides the account of subjective experience

### Additional material on bounds of $\ell^2$-spectral gap for discrete Markov chains with band transition matrices

We analyse the $\ell^2(\pi)$-convergence rate of irreducible and aperiodic
Markov chains with $N$-band transition probability matrix $P$ and with
invariant distribution $\pi$. This analysis is heavily based on: first the
study of the essential spectral radius $r\_{ess}(P\_{|\ell^2(\pi)})$ of
$P\_{|\ell^2(\pi)}$ derived from Hennion's quasi-compactness criteria; second
the connection between the spectral gap property (SG$\_2$) of $P$ on
$\ell^2(\pi)$ and the $V$-geometric ergodicity of $P$. Specifically, (SG$\_2$)
is shown to hold under the condition \alpha\_0 := \sum\_{{m}=-N}^N
\limsup\_{i\rightarrow +\infty} \sqrt{P(i,i+{m})\, P^*(i+{m},i)}\ \textless{}\,
1. Moreover $r\_{ess}(P\_{|\ell^2(\pi)}) \leq \alpha\_0$. Simple conditions
on asymptotic properties of $P$ and of its invariant probability distribution
$\pi$ to ensure that \alpha\_0\textless{}1 are given. In particular this
allows us to obtain estimates of the $\ell^2(\pi)$-geometric convergence rate
of random walks with bounded increments. The specific case of reversible $P$ is
also addressed. Numerical bounds on the convergence rate can be provided via a
truncation procedure. This is illustrated on the Metropolis-Hastings algorithm

### A Higher-Order Theory of Emotional Consciousness

Emotional states of consciousness, or what are typically called emotional feelings, are traditionally viewed as being innately programed in subcortical areas of the brain, and are often treated as different from cognitive states of consciousness, such as those related to the perception of external stimuli. We argue that conscious experiences, regardless of their content, arise from one system in the brain. On this view, what differs in emotional and non-emotional states is the kind of inputs that are processed by a general cortical network of cognition, a network essential for conscious experiences. Although subcortical circuits are not directly responsible for conscious feelings, they provide non-conscious inputs that coalesce with other kinds of neural signals in the cognitive assembly of conscious emotional experiences. In building the case for this proposal, we defend a modified version of what is known as the higher-order theory of consciousness

### Computable bounds of ${\ell}^2$-spectral gap for discrete Markov chains with band transition matrices

We analyse the $\ell^2(\pi)$-convergence rate of irreducible and aperiodic
Markov chains with $N$-band transition probability matrix $P$ and with
invariant distribution $\pi$. This analysis is heavily based on: first the
study of the essential spectral radius $r\_{ess}(P\_{|\ell^2(\pi)})$ of
$P\_{|\ell^2(\pi)}$ derived from Hennion's quasi-compactness criteria; second
the connection between the Spectral Gap property (SG$\_2$) of $P$ on
$\ell^2(\pi)$ and the $V$-geometric ergodicity of $P$. Specifically, (SG$\_2$)
is shown to hold under the condition \alpha\_0 := \sum\_{{m}=-N}^N
\limsup\_{i\rightarrow +\infty} \sqrt{P(i,i+{m})\, P^*(i+{m},i)}\ \textless{}\,
1 Moreover $r\_{ess}(P\_{|\ell^2(\pi)}) \leq \alpha\_0$. Effective bounds on
the convergence rate can be provided from a truncation procedure.Comment: in Journal of Applied Probability, Applied Probability Trust, 2016.
arXiv admin note: substantial text overlap with arXiv:1503.0220

### Automatic computation of quantum-mechanical bound states and wavefunctions

We discuss the automatic solution of the multichannel Schr\"odinger equation.
The proposed approach is based on the use of a CP method for which the step
size is not restricted by the oscillations in the solution. Moreover, this CP
method turns out to form a natural scheme for the integration of the Riccati
differential equation which arises when introducing the (inverse) logarithmic
derivative. A new Pr\"ufer type mechanism which derives all the required
information from the propagation of the inverse of the log-derivative, is
introduced. It improves and refines the eigenvalue shooting process and implies
that the user may specify the required eigenvalue by its index

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