1,390 research outputs found
On a class of infinite words with affine factor complexity
In this article, we consider the factor complexity of a fixed point of a
primitive substitution canonically defined by a beta-numeration system. We
provide a necessary and sufficient condition on the Renyi expansion of 1 for
having an affine factor complexity map C(n), that is, such that C(n)=an+b for
any integer n.Comment: 14 page
Externalizing psychopatholog yand the error-related negativity
Prior research has demonstrated that antisocial behavior, substance-use disorders, and personality dimensions of aggression and impulsivity are indicators of a highly heritable underlying dimension of risk, labeled externalizing. Other work has shown that individual trait constructs within this psychopathology spectrum are associated with reduced self-monitoring, as reflected by amplitude of the error-related negativity (ERN) brain response. In this study of undergraduate subjects, reduced ERN amplitude was associated with higher scores on a self-report measure of the broad externalizing construct that links these various indicators. In addition, the ERN was associated with a response-locked increase in anterior theta (4–7 Hz) oscillation; like the ERN, this theta response to errors was reduced among high-externalizing individuals. These findings suggest that neurobiologically based deficits in endogenous action monitoring may underlie generalized risk for an array of impulse-control problems
Dyadic Predictors of Child Body Shame in a Polish and Italian Sample
The present study aimed at assessing the predictors (related to the functioning of a parent-child dyad) of child body shame. Therefore, in the main analysis we examined relationships among child body shame, child perfectionism, child body dissatisfaction, parent body shame, parent perfectionism, and parent body dissatisfaction. In our main hypothesis we assumed that higher levels of the abovementioned parent functioning-related variables would be associated with higher child body shame after accounting for the effects of the foregoing child functioning-related variables. The analysis finally included complete data from 420 participants, i.e., a 115 Polish and 95 Italian parent-child dyad. Participants completed: (a) child: the Objectified Body Consciousness Scale for Youth, the Child-Adolescent Perfectionism Scale, the Children’s Body Image Scale/the Figure Rating Scale; (b) parent: the Objectified Body Consciousness Scale, the Frost Multidimensional Perfectionism Scale, and the Contour Drawing Rating Scale. The results of a correlational analysis show that in both the Polish and Italian samples, the higher the level of child body shame, the higher the level of the following variables: child perfectionism, child body dissatisfaction, parent perfectionism, and parent body dissatisfaction. Interestingly, the only insignificant relationship in both samples is the association between body shame in both members of the child-parent dyad. Moreover, all steps of the regressions were significant in both Polish and Italian samples. It turned out that only in the Italian sample were all predictors significantly associated with a child’s body shame (in the Polish sample there was no significant association between child’s body shame and parent’s perfectionism). To sum up, the above studies show the importance of considering the functioning of the parent-child dyad in understanding child body shame. These findings suggest that parents’ attitudes toward their bodies and their beliefs about an ideal self should be taken into account when planning interventions to improve children’s and adolescents’ attitudes toward their bodies. This is so because it is possible for children to internalize their parents’ beliefs about how to look and how critical one should be of themselves, which can result in strong body shame when they are not perfect enough against the internalized ideal. Therefore, it is also necessary to make parents aware that children’s attitude toward their body is often a reflection of parents’ attitude toward the body
Beating noise with abstention in state estimation
We address the problem of estimating pure qubit states with non-ideal (noisy)
measurements in the multiple-copy scenario, where the data consists of a number
N of identically prepared qubits. We show that the average fidelity of the
estimates can increase significantly if the estimation protocol allows for
inconclusive answers, or abstentions. We present the optimal such protocol and
compute its fidelity for a given probability of abstention. The improvement
over standard estimation, without abstention, can be viewed as an effective
noise reduction. These and other results are exemplified for small values of N.
For asymptotically large N, we derive analytical expressions of the fidelity
and the probability of abstention, and show that for a fixed fidelity gain the
latter decreases with N at an exponential rate given by a Kulback-Leibler
(relative) entropy. As a byproduct, we obtain an asymptotic expression in terms
of this very entropy of the probability that a system of N qubits, all prepared
in the same state, has a given total angular momentum. We also discuss an
extreme situation where noise increases with N and where estimation with
abstention provides a most significant improvement as compared to the standard
approach
Psychophysiological Measures of Driver Distraction and Workload While Intoxicated
The crash risk associated with cell phone use while driving is acontentious issue. Many states are introducing Advanced Traveler InformationSystems (ATIS) that may be accessed with cell phones while driving (e.g., 511Traveler Information Services). In these contexts, there is a need for relevantresearch to determine the risk of cell phone use. This study compared driverperformance while conversing on a hands-free cell phone to conditions ofoperating common in-vehicle controls (e.g., radio, fan, air conditioning) andalcohol intoxication (BAC 0.08). In addition, the study examined the combinedeffects of being distracted and being intoxicated given that there may be a higherrisk of a crash if the driver engages in a combination of risk factors. Duringsimulated traffic scenarios, resource allocation was assessed through an eventrelatedpotential (ERP) novelty oddball paradigm. Intoxicated drivers were lessattentive to all stimuli and drivers engaged in secondary tasks had weakerresponses to unexpected novel sounds in brain regions associated with evaluativeprocessing. Drivers conversing on the cell phone and in-vehicle tasks while soberhad lower accuracy during the target tone task than intoxicated drivers notcompleting any secondary task
Exploring the randomness of Directed Acyclic Networks
The feed-forward relationship naturally observed in time-dependent processes
and in a diverse number of real systems -such as some food-webs and electronic
and neural wiring- can be described in terms of so-called directed acyclic
graphs (DAGs). An important ingredient of the analysis of such networks is a
proper comparison of their observed architecture against an ensemble of
randomized graphs, thereby quantifying the {\em randomness} of the real systems
with respect to suitable null models. This approximation is particularly
relevant when the finite size and/or large connectivity of real systems make
inadequate a comparison with the predictions obtained from the so-called {\em
configuration model}. In this paper we analyze four methods of DAG
randomization as defined by the desired combination of topological invariants
(directed and undirected degree sequence and component distributions) aimed to
be preserved. A highly ordered DAG, called \textit{snake}-graph and a
Erd\:os-R\'enyi DAG were used to validate the performance of the algorithms.
Finally, three real case studies, namely, the \textit{C. elegans} cell lineage
network, a PhD student-advisor network and the Milgram's citation network were
analyzed using each randomization method. Results show how the interpretation
of degree-degree relations in DAGs respect to their randomized ensembles depend
on the topological invariants imposed. In general, real DAGs provide disordered
values, lower than the expected by chance when the directedness of the links is
not preserved in the randomization process. Conversely, if the direction of the
links is conserved throughout the randomization process, disorder indicators
are close to the obtained from the null-model ensemble, although some
deviations are observed.Comment: 13 pages, 5 figures and 5 table
On the origin of ambiguity in efficient communication
This article studies the emergence of ambiguity in communication through the
concept of logical irreversibility and within the framework of Shannon's
information theory. This leads us to a precise and general expression of the
intuition behind Zipf's vocabulary balance in terms of a symmetry equation
between the complexities of the coding and the decoding processes that imposes
an unavoidable amount of logical uncertainty in natural communication.
Accordingly, the emergence of irreversible computations is required if the
complexities of the coding and the decoding processes are balanced in a
symmetric scenario, which means that the emergence of ambiguous codes is a
necessary condition for natural communication to succeed.Comment: 28 pages, 2 figure
Diversity, competition, extinction: the ecophysics of language change
As early indicated by Charles Darwin, languages behave and change very much
like living species. They display high diversity, differentiate in space and
time, emerge and disappear. A large body of literature has explored the role of
information exchanges and communicative constraints in groups of agents under
selective scenarios. These models have been very helpful in providing a
rationale on how complex forms of communication emerge under evolutionary
pressures. However, other patterns of large-scale organization can be described
using mathematical methods ignoring communicative traits. These approaches
consider shorter time scales and have been developed by exploiting both
theoretical ecology and statistical physics methods. The models are reviewed
here and include extinction, invasion, origination, spatial organization,
coexistence and diversity as key concepts and are very simple in their defining
rules. Such simplicity is used in order to catch the most fundamental laws of
organization and those universal ingredients responsible for qualitative
traits. The similarities between observed and predicted patterns indicate that
an ecological theory of language is emerging, supporting (on a quantitative
basis) its ecological nature, although key differences are also present. Here
we critically review some recent advances lying and outline their implications
and limitations as well as open problems for future research.Comment: 17 Pages. A review on current models from statistical Physics and
Theoretical Ecology applied to study language dynamic
Topological reversibility and causality in feed-forward networks
Systems whose organization displays causal asymmetry constraints, from
evolutionary trees to river basins or transport networks, can be often
described in terms of directed paths (causal flows) on a discrete state space.
Such a set of paths defines a feed-forward, acyclic network. A key problem
associated with these systems involves characterizing their intrinsic degree of
path reversibility: given an end node in the graph, what is the uncertainty of
recovering the process backwards until the origin? Here we propose a novel
concept, \textit{topological reversibility}, which rigorously weigths such
uncertainty in path dependency quantified as the minimum amount of information
required to successfully revert a causal path. Within the proposed framework we
also analytically characterize limit cases for both topologically reversible
and maximally entropic structures. The relevance of these measures within the
context of evolutionary dynamics is highlighted.Comment: 9 pages, 3 figure
Forced expression of Lmx1b enhances differentiation of mouse ES cells into serotonergic neurons
The LIM homeodomain transcription factor Lmx1b is a key factor in the specification of the serotonergic neurotransmitter phenotype. Here, we explored the capacity of Lmx1b to direct differentiation of mouse embryonic stem (mES) cells into serotonergic neurons. mES cells stably expressing human Lmx1b were generated by lentiviral vector infection. Clones expressing Lmx1b at a low level showed increased neurogenesis and elevated production of neurons expressing serotonin, serotonin transporter, Tryptophan hydroxylase 2, and transcription factor Pet1, the landmarks of serotonergic differentiation. To explore the role of Lmx1b in the specification of the serotonin neurotransmission phenotype further, a conditional system making use of a floxed inducible vector targeted into the ROSA26 locus and a hormone-dependent Cre recombinase was engineered. This novel strategy was tested with the reporter gene encoding human placental alkaline phosphatase, and demonstrated its capacity to drive transgene expression in nestin+ neural progenitors and in Tuj1+ neurons. When it was applied to the inducible expression of human Lmx1b, it resulted in elevated expression of serotonergic markers. Treatment of neural precursors with the floor plate signal Sonic hedgehog further enhanced differentiation of Lmx1b-overexpressing neural progenitors into neurons expressing 5-HT, serotonin transporter, Tryptophan hydroxylase 2 and Pet1, when compared to Lmx1b-non expressing progenitors. Together, our results demonstrate the capacity of Lmx1b to specify a serotonin neurotransmitter phenotype when overexpressed in mESC-derived neural progenitors
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