145 research outputs found
Elaborate visual and acoustic signals evolve independently in a large, phenotypically diverse radiation of songbirds
The concept of a macroevolutionary trade-off among sexual signals has a storied history in evolutionary biology. Theory predicts that if multiple sexual signals are costly for males to produce or maintain and females prefer a single, sexually selected trait, then an inverse correlation between sexual signal elaborations is expected among species. However, empirical evidence for what has been termed the \u27transfer hypothesis\u27 is mixed, which may reflect different selective pressures among lineages, evolutionary covariates or methodological differences among studies. Here,we examine interspecific correlations between song and plumage elaboration in a phenotypically diverse, widespread radiation of songbirds, the tanagers. The tanagers (Thraupidae) are the largest family of songbirds, representing nearly 10% of all songbirds. We assess variation in song and plumage elaboration across 301 species, representing the largest scale comparative study of multimodal sexual signalling to date. We consider whether evolutionary covariates, including habitat, structural and carotenoid-based coloration, and subfamily groupings influence the relationship between song and plumage elaboration. We find that song and plumage elaboration are uncorrelated when considering all tanagers, although the relationship between song and plumage complexity varies among subfamilies. Taken together, we find that elaborate visual and vocal sexual signals evolve independently among tanagers. © 2014 The Authors Published by the Royal Society. All rights reserved
âAll the Worldâs a Stageâ and Each Has a Role to Play: A Collaborative Cross-Unit Metadata Project in Five Acts
The COVID-19 pandemic and the resulting shift to working from home proved a boon for digital collections. At Clemson University Libraries the metadata team facilitated a work-from-home project, during which 14 employees across two units described a collection of over 2400 photographs. From the standpoint of both the metadata reviewers and metadata creators, we will provide an overview of the project and workflows, including how training, communication, metadata creation, and quality control were managed remotely. This presentation reflects a balanced cross-unit perspective on what worked well and what could be improved for future virtual collaborative projects
âAll the worldâs a stageâ and each has a role to play: A collaborative cross-unit metadata project in five acts
As a result of the COVID-19 pandemic, the metadata team at Clemson University Libraries facilitated a work-from-home project, during which 14 employees across two units described a collection of over 2,400 photographs. From the standpoint of both the metadata reviewers and metadata creators, this session provided an overview of the project, including how it was managed remotely. This presentation reflects a balanced cross-unit perspective on what worked well and what could be improved
Infant cortex responds to other humans from shortly after birth
A significant feature of the adult human brain is its ability to selectively process information about conspecifics. Much debate has centred on whether this specialization is primarily a result of phylogenetic adaptation, or whether the brain acquires expertise in processing social stimuli as a result of its being born into an intensely social environment. Here we study the haemodynamic response in cortical areas of newborns (1â5 days old) while they passively viewed dynamic human or mechanical action videos. We observed activation selective to a dynamic face stimulus over bilateral posterior temporal cortex, but no activation in response to a moving human arm. This selective activation to the social stimulus correlated with age in hours over the first few days post partum. Thus, even very limited experience of face-to-face interaction with other humans may be sufficient to elicit social stimulus activation of relevant cortical regions
Constraints on the Ultra-High Energy Neutrino Flux from Gamma-Ray Bursts from a Prototype Station of the Askaryan Radio Array
We report on a search for ultra-high-energy (UHE) neutrinos from gamma-ray
bursts (GRBs) in the data set collected by the Testbed station of the Askaryan
Radio Array (ARA) in 2011 and 2012. From 57 selected GRBs, we observed no
events that survive our cuts, which is consistent with 0.12 expected background
events. Using NeuCosmA as a numerical GRB reference emission model, we estimate
upper limits on the prompt UHE GRB neutrino fluence and quasi-diffuse flux from
to GeV. This is the first limit on the prompt UHE GRB
neutrino quasi-diffuse flux above GeV.Comment: 14 pages, 8 figures, Published in Astroparticle Physics Journa
First Constraints on the Ultra-High Energy Neutrino Flux from a Prototype Station of the Askaryan Radio Array
The Askaryan Radio Array (ARA) is an ultra-high energy ( eV) cosmic
neutrino detector in phased construction near the South Pole. ARA searches for
radio Cherenkov emission from particle cascades induced by neutrino
interactions in the ice using radio frequency antennas ( MHz)
deployed at a design depth of 200 m in the Antarctic ice. A prototype ARA
Testbed station was deployed at m depth in the 2010-2011 season and
the first three full ARA stations were deployed in the 2011-2012 and 2012-2013
seasons. We present the first neutrino search with ARA using data taken in 2011
and 2012 with the ARA Testbed and the resulting constraints on the neutrino
flux from eV.Comment: 26 pages, 15 figures. Since first revision, added section on
systematic uncertainties, updated limits and uncertainty band with
improvements to simulation, added appendix describing ray tracing algorithm.
Final revision includes a section on cosmic ray backgrounds. Published in
Astropart. Phys.
Performance of two Askaryan Radio Array stations and first results in the search for ultra-high energy neutrinos
Ultra-high energy neutrinos are interesting messenger particles since, if
detected, they can transmit exclusive information about ultra-high energy
processes in the Universe. These particles, with energies above
, interact very rarely. Therefore, detectors that
instrument several gigatons of matter are needed to discover them. The ARA
detector is currently being constructed at South Pole. It is designed to use
the Askaryan effect, the emission of radio waves from neutrino-induced cascades
in the South Pole ice, to detect neutrino interactions at very high energies.
With antennas distributed among 37 widely-separated stations in the ice, such
interactions can be observed in a volume of several hundred cubic kilometers.
Currently 3 deep ARA stations are deployed in the ice of which two have been
taking data since the beginning of the year 2013. In this publication, the ARA
detector "as-built" and calibrations are described. Furthermore, the data
reduction methods used to distinguish the rare radio signals from overwhelming
backgrounds of thermal and anthropogenic origin are presented. Using data from
only two stations over a short exposure time of 10 months, a neutrino flux
limit of is
calculated for a particle energy of 10^{18}eV, which offers promise for the
full ARA detector.Comment: 21 pages, 34 figures, 1 table, includes supplementary materia
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