Rapid modulation of sensory processing induced by stimulus conflict

Humans are constantly confronted with environmental stimuli that conflict with task goals and can interfere with successful behavior. Prevailing theories propose the existence of cognitive control mechanisms that can suppress the processing of conflicting input and enhance that of the relevant input. However, the temporal cascade of brain processes invoked in response to conflicting stimuli remains poorly understood. By examining evoked electrical brain responses in a novel, hemifield-specific, visual-flanker task, we demonstrate that task-irrelevant conflicting stimulus input is quickly detected in higher level executive regions while simultaneously inducing rapid, recurrent modulation of sensory processing in the visual cortex. Importantly, however, both of these effects are larger for individuals with greater incongruency-related RT slowing. The combination of neural activation patterns and behavioral interference effects suggest that this initial sensory modulation induced by conflicting stimulus inputs reflects performance-degrading attentional distraction because of their incompatibility rather than any rapid task-enhancing cognitive control mechanisms. The present findings thus provide neural evidence for a model in which attentional distraction is the key initial trigger for the temporal cascade of processes by which the human brain responds to conflicting stimulus input in the environment

Challenges for wireless mesh networks to provide reliable carrier-grade services

Provision of mobile and wireless services today within a competitive environment and driven by a huge amount of steadily emerging new services and applications is both challenge and chance for radio network operators. Deployment and operation of an infrastructure for mobile and wireless broadband connectivity generally requires planning effort and large investments. A promising approach to reduce expenses for radio access networking is offered by Wireless Mesh Networks (WMNs). Here traditional dedicated backhaul connections to each access point are replaced by wireless multi-hop links between neighbouring access nodes and few gateways to the backbone employing standard radio technology. Such a solution provides at the same time high flexibility in both deployment and the amount of offered capacity and shall reduce overall expenses. On the other hand currently available mesh solutions do not provide carrier grade service quality and reliability and often fail to cope with high traffic load. EU project CARMEN (CARrier grade MEsh Networks) was initiated to incorporate different heterogeneous technologies and new protocols to allow for reliable transmission over "best effort" radio channels, to support a reliable mobility and network management, self-configuration and dynamic resource usage, and thus to offer a permanent or temporary broadband access at high cost efficiency. The contribution provides an overview on preliminary project results with focus on main technical challenges from a research and implementation point of view. Especially impact of mesh topology on the overall system performance in terms of throughput and connection reliability and aspects of a dedicated hybrid mobility management solution will be discussed.European Community's Seventh Framework ProgramPublicad

Asymptotic expansions for Riesz fractional derivatives of Airy functions and applications

Riesz fractional derivatives of a function, $D_{x}^{\alpha}f(x)$ (also called Riesz potentials), are defined as fractional powers of the Laplacian. Asymptotic expansions for large $x$ are computed for the Riesz fractional derivatives of the Airy function of the first kind, $Ai(x)$, and the Scorer function, $Gi(x)$. Reduction formulas are provided that allow one to express Riesz potentials of products of Airy functions, $D_{x}^{\alpha}\left\{ Ai(x)Bi(x)\right\}$ and $D_{x}^{\alpha}\left\{ Ai^{2}(x)\right\}$, via $D_{x}^{\alpha}Ai(x)$ and $D_{x}^{\alpha}Gi(x)$. Here $Bi(x)$ is the Airy function of the second type. Integral representations are presented for the function $A_{2}\left(a,b;x\right)=Ai\left(x-a\right)Ai\left(x-b\right)$ with $a, b\in\mathbb{R}$ and its Hilbert transform. Combined with the above asymptotic expansions they can be used for computing asymptotics of the Hankel transform of $D_{x}^{\alpha}\left\{ A_{2}\left(a,b;x\right)\right\}$. These results are used for obtaining the weak rotation approximation for the Ostrovsky equation (asymptotics of the fundamental solution of the linearized Cauchy problem as the rotation parameter tends to zero)

Asymptotic expansions for Riesz potentials of Airy functions and their products

Riesz potentials of a function are defined as fractional powers of the Laplacian. Asymptotic expansions for $x\to\pm\infty$ are derived for the Riesz potentials of the Airy function $Ai(x)$ and the Scorer function $Gi(x)$. Reduction formulas are provided that allow to compute Riesz potentials of the products of Airy functions $Ai^2(x)$ and $Ai(x)Bi(x)$, where $Bi(x)$ is the Airy function of the second type, via the Riesz potentials of $Ai(x)$ and $Gi(x)$. Integral representations are given for the function $A_{2}\left(a,b;x\right)=Ai\left(x-a\right)Ai\left(x-b\right)$ with $a, b\in \mathbf{R}$, and its Hilbert transform. Combined with the above asymptotic expansions they can be used for obtaining asymptotics of the Hankel transform of Riesz potentials of $A_{2}(a,b;x)$. The study of the above Riesz fractional derivatives can be used for establishing new properties of Korteweg-de Vries-type equations

Asymptotic expansions for Riesz fractional derivatives of Airy functions and applications

Riesz fractional derivatives of a function, $D_{x}^{\alpha}f(x)$ (also called Riesz potentials), are defined as fractional powers of the Laplacian. Asymptotic expansions for large $x$ are computed for the Riesz fractional derivatives of the Airy function of the first kind, $Ai(x)$, and the Scorer function, $Gi(x)$. Reduction formulas are provided that allow one to express Riesz potentials of products of Airy functions, $D_{x}^{\alpha}\left\{ Ai(x)Bi(x)\right\}$ and $D_{x}^{\alpha}\left\{ Ai^{2}(x)\right\}$, via $D_{x}^{\alpha}Ai(x)$ and $D_{x}^{\alpha}Gi(x)$. Here $Bi(x)$ is the Airy function of the second type. Integral representations are presented for the function $A_{2}\left(a,b;x\right)=Ai\left(x-a\right)Ai\left(x-b\right)$ with $a, b\in\mathbb{R}$ and its Hilbert transform. Combined with the above asymptotic expansions they can be used for computing asymptotics of the Hankel transform of $D_{x}^{\alpha}\left\{ A_{2}\left(a,b;x\right)\right\}$. These results are used for obtaining the weak rotation approximation for the Ostrovsky equation (asymptotics of the fundamental solution of the linearized Cauchy problem as the rotation parameter tends to zero)

Googling Referendum Campaigns: Analyzing Online Search Patterns Regarding Swiss Direct-Democratic Votes

In direct democracies, voters are faced with considerable information demands. Although search engines are an important gateway to political information, it is still unclear what role they play in citizens’ information behavior regarding referendum campaigns. Moreover, few studies have examined the search terms that citizens use when searching for political information and the potential “user-input biases” in this regard. Therefore, we investigate to what extent citizens search online for information about upcoming referendums and what differences emerge between proponents, opponents, and non-voters regarding the search terms they used and the results they visited, related to three national ballot proposals voted on in Switzerland on November 28, 2021. The study combines cross-sectional survey data with longitudinal digital trace data containing participants’ Google Search histories obtained through data donations. Our findings show that participants rarely used Google to search for information about upcoming referendums. Moreover, most ballot-related searches employed rather neutral search terms. Nevertheless, a qualitative analysis of the search terms points to differences between different voting groups, particularly for the most prominent proposal around a Covid-19 law. The study provides interesting insight into how citizens search for information online during national referendum campaigns

Googling Referendum Campaigns: Analyzing Online Search Patterns Regarding Swiss Direct-Democratic Votes

In direct democracies, voters are faced with considerable information demands. Although search engines are an important gateway to political information, it is still unclear what role they play in citizens’ information behavior regarding referendum campaigns. Moreover, few studies have examined the search terms that citizens use when searching for political information and the potential “user-input biases” in this regard. Therefore, we investigate to what extent citizens search online for information about upcoming referendums and what differences emerge between proponents, opponents, and non-voters regarding the search terms they used and the results they visited, related to three national ballot proposals voted on in Switzerland on November 28, 2021. The study combines cross-sectional survey data with longitudinal digital trace data containing participants’ Google Search histories obtained through data donations. Our findings show that participants rarely used Google to search for information about upcoming referendums. Moreover, most ballot-related searches employed rather neutral search terms. Nevertheless, a qualitative analysis of the search terms points to differences between different voting groups, particularly for the most prominent proposal around a Covid-19 law. The study provides interesting insight into how citizens search for information online during national referendum campaigns

Optimal Constraints on Local Primordial Non-Gaussianity from the Two-Point Statistics of Large-Scale Structure

One of the main signatures of primordial non-Gaussianity of the local type is a scale-dependent correction to the bias of large-scale structure tracers such as galaxies or clusters, whose amplitude depends on the bias of the tracers itself. The dominant source of noise in the power spectrum of the tracers is caused by sampling variance on large scales (where the non-Gaussian signal is strongest) and shot noise arising from their discrete nature. Recent work has argued that one can avoid sampling variance by comparing multiple tracers of different bias, and suppress shot noise by optimally weighting halos of different mass. Here we combine these ideas and investigate how well the signatures of non-Gaussian fluctuations in the primordial potential can be extracted from the two-point correlations of halos and dark matter. On the basis of large $N$-body simulations with local non-Gaussian initial conditions and their halo catalogs we perform a Fisher matrix analysis of the two-point statistics. Compared to the standard analysis, optimal weighting- and multiple-tracer techniques applied to halos can yield up to one order of magnitude improvements in \fnl-constraints, even if the underlying dark matter density field is not known. We compare our numerical results to the halo model and find satisfactory agreement. Forecasting the optimal \fnl-constraints that can be achieved with our methods when applied to existing and future survey data, we find that a survey of $50h^{-1}\mathrm{Gpc}^3$ volume resolving all halos down to 10^{11}\hMsun at $z=1$ will be able to obtain \sigma_{\fnl}\sim1 (68% cl), a factor of $\sim20$ improvement over the current limits. Decreasing the minimum mass of resolved halos, increasing the survey volume or obtaining the dark matter maps can further improve these limits, potentially reaching the level of \sigma_{\fnl}\sim0.1. (abridged)Comment: V1: 23 pages, 12 figures, submitted to PRD. V2: 24 pages, added appendix and citations, matched to PRD published versio

Status of the Solar Neutrino Puzzle

Using the latest results from the solar neutrino experiments and a few standard assumptions, I show that the popular solar models are ruled out at the 3$\sigma$ level or at least TWO of the experiments are incorrect. Alternatively, one of the assumptions could be in error. These assumptions are spelled out in detail as well as how each one affects the argument.Comment: Latex, 8 pages + 4 uuencoded figures, minor changes made, FERMILAB-PUB/273-