1,998 research outputs found
Who bullies whom at a garden feeder? Interspecific agonistic interactions of small passerines during a cold winter
Interspecific agonistic interactions are important
selective factors for maintaining ecological niches of
different species, but their outcome is difficult to predict
a priori. Here, we examined the direction and intensity of
interspecific interactions in an assemblage of small passerines
at a garden feeder, focussing on three finch species
of various body sizes. We found that large and mediumsized
birds usually initiated and won agonistic interactions
with smaller species. Also, the frequency of fights increased
with decreasing differences in body size between
the participants. Finally, the probability of engaging in a
fight increased with the number of birds at the feeder
Heavy anion solvation of polarity fluctuations in Pnictides
Once again the condensed matter world has been surprised by the discovery of
yet another class of high temperature superconductors. The discovery of
iron-pnictide (FeAs) and chalcogenide (FeSe) based superconductors with a
of up to 55 K is again evidence of how complex the many body problem really is,
or in another view how resourceful nature is. The first reactions would of
course be that these new materials must in some way be related to the
copper-oxide based superconductors for which a large number of theories exist
although a general consensus regarding the correct theory has not yet been
reached. Here we point out that the basic physical paradigm of the new iron
based superconductors is entirely different from the cuprates. Their
fundamental properties, structural and electronic, are dominated by the
exceptionally large pnictide polarizabilities
Holographic and Wilsonian Renormalization Groups
We develop parallels between the holographic renormalization group in the
bulk and the Wilsonian renormalization group in the dual field theory. Our
philosophy differs from most previous work on the holographic RG; the most
notable feature is the key role of multi-trace operators. We work out the forms
of various single- and double-trace flows. The key question, `what cutoff on
the field theory corresponds to a radial cutoff in the bulk?' is left
unanswered, but by sharpening the analogy between the two sides we identify
possible directions.Comment: 31 pages, 3 figures. v2: Minor clarifications. Added reference
Attention-dependent modulation of cortical taste circuits revealed by granger causality with signal-dependent noise
We show, for the first time, that in cortical areas, for example the insular, orbitofrontal, and lateral prefrontal cortex, there is signal-dependent noise in the fMRI blood-oxygen level dependent (BOLD) time series, with the variance of the noise increasing approximately linearly with the square of the signal. Classical Granger causal models are based on autoregressive models with time invariant covariance structure, and thus do not take this signal-dependent noise into account. To address this limitation, here we describe a Granger causal model with signal-dependent noise, and a novel, likelihood ratio test for causal inferences. We apply this approach to the data from an fMRI study to investigate the source of the top-down attentional control of taste intensity and taste pleasantness processing. The Granger causality with signal-dependent noise analysis reveals effects not identified by classical Granger causal analysis. In particular, there is a top-down effect from the posterior lateral prefrontal cortex to the insular taste cortex during attention to intensity but not to pleasantness, and there is a top-down effect from the anterior and posterior lateral prefrontal cortex to the orbitofrontal cortex during attention to pleasantness but not to intensity. In addition, there is stronger forward effective connectivity from the insular taste cortex to the orbitofrontal cortex during attention to pleasantness than during attention to intensity. These findings indicate the importance of explicitly modeling signal-dependent noise in functional neuroimaging, and reveal some of the processes involved in a biased activation theory of selective attention
Prenatal exposures and exposomics of asthma
This review examines the causal investigation of preclinical development of childhood asthma using exposomic tools. We examine the current state of knowledge regarding early-life exposure to non-biogenic indoor air pollution and the developmental modulation of the immune system. We examine how metabolomics technologies could aid not only in the biomarker identification of a particular asthma phenotype, but also the mechanisms underlying the immunopathologic process. Within such a framework, we propose alternate components of exposomic investigation of asthma in which, the exposome represents a reiterative investigative process of targeted biomarker identification, validation through computational systems biology and physical sampling of environmental medi
The narrative self, distributed memory, and evocative objects
In this article, I outline various ways in which artifacts are interwoven with autobiographical memory systems and conceptualize what this implies for the self. I first sketch the narrative approach to the self, arguing that who we are as persons is essentially our (unfolding) life story, which, in turn, determines our present beliefs and desires, but also directs our future goals and actions. I then argue that our autobiographical memory is partly anchored in our embodied interactions with an ecology of artifacts in our environment. Lifelogs, photos, videos, journals, diaries, souvenirs, jewelry, books, works of art, and many other meaningful objects trigger and sometimes constitute emotionally-laden autobiographical memories. Autobiographical memory is thus distributed across embodied agents and various environmental structures. To defend this claim, I draw on and integrate distributed cognition theory and empirical research in human-technology interaction. Based on this, I conclude that the self is neither defined by psychological states realized by the brain nor by biological states realized by the organism, but should be seen as a distributed and relational construct
Mixed RG Flows and Hydrodynamics at Finite Holographic Screen
We consider quark-gluon plasma with chemical potential and study
renormalization group flows of transport coefficients in the framework of
gauge/gravity duality. We first study them using the flow equations and compare
the results with hydrodynamic results by calculating the Green functions on the
arbitrary slice. Two results match exactly. Transport coefficients at arbitrary
scale is ontained by calculating hydrodynamics Green functions. When either
momentum or charge vanishes, transport coefficients decouple from each other.Comment: 22 pages, 6 figure
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