2,814 research outputs found
Colony size predicts division of labour in Attine ants
Division of labour is central to the ecological success of eusocial insects, yet the evolutionary factors driving increases in complexity in division of labour are little known. The sizeâcomplexity hypothesis proposes that, as larger colonies evolve, both non-reproductive and reproductive division of labour become more complex as workers and queens act to maximize inclusive fitness. Using a statistically robust phylogenetic comparative analysis of social and environmental traits of species within the ant tribe Attini, we show that colony size is positively related to both non-reproductive (worker size variation) and reproductive (queenâworker dimorphism) division of labour. The results also suggested that colony size acts on non-reproductive and reproductive division of labour in different ways. Environmental factors, including measures of variation in temperature and precipitation, had no significant effects on any division of labour measure or colony size. Overall, these results support the sizeâcomplexity hypothesis for the evolution of social complexity and division of labour in eusocial insects. Determining the evolutionary drivers of colony size may help contribute to our understanding of the evolution of social complexity
Colony size predicts division of labour in Attine ants
Division of labour is central to the ecological success of eusocial insects, yet the evolutionary factors driving increases in complexity in division of labour are little known. The sizeâcomplexity hypothesis proposes that, as larger colonies evolve, both non-reproductive and reproductive division of labour become more complex as workers and queens act to maximize inclusive fitness. Using a statistically robust phylogenetic comparative analysis of social and environmental traits of species within the ant tribe Attini, we show that colony size is positively related to both non-reproductive (worker size variation) and reproductive (queenâworker dimorphism) division of labour. The results also suggested that colony size acts on non-reproductive and reproductive division of labour in different ways. Environmental factors, including measures of variation in temperature and precipitation, had no significant effects on any division of labour measure or colony size. Overall, these results support the sizeâcomplexity hypothesis for the evolution of social complexity and division of labour in eusocial insects. Determining the evolutionary drivers of colony size may help contribute to our understanding of the evolution of social complexity
Low-Energy Theorems from Holography
In the context of gauge/gravity duality, we verify two types of gauge theory
low-energy theorems, the dilation Ward identities and the decoupling of heavy
flavor. First, we provide an analytic proof of non-trivial dilation Ward
identities for a theory holographically dual to a background with gluon
condensate (the self-dual Liu--Tseytlin background). In this way an important
class of low-energy theorems for correlators of different operators with the
trace of the energy-momentum tensor is established, which so far has been
studied in field theory only. Another low-energy relationship, the so-called
decoupling theorem, is numerically shown to hold universally in three
holographic models involving both the quark and the gluon condensate. We show
this by comparing the ratio of the quark and gluon condensates in three
different examples of gravity backgrounds with non-trivial dilaton flow. As a
by-product of our study, we also obtain gauge field condensate contributions to
meson transport coefficients.Comment: 32 pages, 4 figures, two references added, typos remove
DNA-based Self-Assembly of Chiral Plasmonic Nanostructures with Tailored Optical Response
Surface plasmon resonances generated in metallic nanostructures can be
utilized to tailor electromagnetic fields. The precise spatial arrangement of
such structures can result in surprising optical properties that are not found
in any naturally occurring material. Here, the designed activity emerges from
collective effects of singular components equipped with limited individual
functionality. Top-down fabrication of plasmonic materials with a predesigned
optical response in the visible range by conventional lithographic methods has
remained challenging due to their limited resolution, the complexity of
scaling, and the difficulty to extend these techniques to three-dimensional
architectures. Molecular self-assembly provides an alternative route to create
such materials which is not bound by the above limitations. We demonstrate how
the DNA origami method can be used to produce plasmonic materials with a
tailored optical response at visible wavelengths. Harnessing the assembly power
of 3D DNA origami, we arranged metal nanoparticles with a spatial accuracy of 2
nm into nanoscale helices. The helical structures assemble in solution in a
massively parallel fashion and with near quantitative yields. As a designed
optical response, we generated giant circular dichroism and optical rotary
dispersion in the visible range that originates from the collective
plasmon-plasmon interactions within the nanohelices. We also show that the
optical response can be tuned through the visible spectrum by changing the
composition of the metal nanoparticles. The observed effects are independent of
the direction of the incident light and can be switched by design between left-
and right-handed orientation. Our work demonstrates the production of complex
bulk materials from precisely designed nanoscopic assemblies and highlights the
potential of DNA self-assembly for the fabrication of plasmonic nanostructures.Comment: 5 pages, 4 figure
Lithium and boron in calcified tissues of vicuna and its relation to the chronic exposure by water ingestion in the Andean lithium triangle
Vicuna is a wild, endangered species of Andean camelid living in the hyperarid Andean plateau. In the central part of the plateau, the Lithium Triangle defines a zone with lithiumârich salt pans. Brine pools naturally form within the salt pans, and the adaptation strategy of vicuna consists of drinking from brine pools. Together with reporting the first chemical data on vicuna bones and teeth, we analyzed lithium, boron, and arsenic in water and brines, with the aim of assessing their relation to chronic exposure by water ingestion. We collected and analyzed bones of vicuna specimens lying in an Andean salt pan, together with brine and water samples. Brine and water samples are highly saline and contain large amounts of lithium, boron, and arsenic. Lithium (13.50â40 mg kgâ1 ) and boron (40â46.80 mg kgâ1 ), but not arsenic, were found in the vicuna bones and teeth. Based on our results and on previously reported data on human tissues in the Andes, we conducted statistical assessments of the relationships between lithium and boron in body tissues and water samples, and discuss their environmental significance in the context of the Lithium Triangle.Fil: LĂłpez Steinmetz, Romina Lucrecia. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Universidad Nacional de Jujuy. Instituto de GeologĂa Minera; ArgentinaFil: Fong, Shao Bing. University of Melbourne; AustraliaFil: Boyer, Emile. Universite de Rennes I; FranciaFil: LĂłpez Steinmetz, Lorena Cecilia. Universidad Nacional de CĂłrdoba. Instituto de Investigaciones PsicolĂłgicas. - Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de Investigaciones PsicolĂłgicas; ArgentinaFil: Tejerina, Norberto Elio. Universidad Nacional de Jujuy. Instituto de GeologĂa Minera; ArgentinaFil: Meuric, Vincent. Universite de Rennes I; Franci
How do stroke survivors and their carers use practitioners' advice on secondary prevention medications? Qualitative study of an online forum
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Secondary prevention medications reduce risk of stroke recurrence, yet many people do not receive recommended treatment, nor take medications optimally.
: Exploring how patients report making use of practitioners' advice on secondary prevention medicines on an online forum and what feedback was received from other participants.
: Thematic analysis of the archive of Talkstroke (2004-2011), UK. Posts including any secondary prevention medication terms, General Practitioner (GP) and their replies were identified.
: Fifity participants talked about practitioners' advice on secondary prevention medications in 43 discussion threads. Patients consulted practitioners for reassurance and dealing with side effects. Practitioners' advice varied from altering to maintaining current treatment. Three main themes emerged from the use of practitioners' advice: patients following advice (reassured, happy when side effects made tolerable, or still retaining anxiety about treatment); patients not following advice (admitting adherence on-off or stopping medications as side effects still not tolerable); asking other participants for feedback on advice received. Practitioners' advice was disregarded mainly when related to dealing with statin side effects, after one or two consultations. Themes for feedback involved sharing experience, directing back to practitioners, or to external evidence.
: Side effects of secondary prevention medications and statins in particular, cause anxiety and resentment in some patients, and their concerns are not always addressed by practitioners. Practitioners could consider more proactive strategies to manage such side effects. Forum feedback was appropriate and supportive of the practitioners' advice received. Our findings from peer-to-peer online conversations confirm and widen previous research.Anna De Simoni is funded by a NIHR Academic Clinical Lectureship
Performance Analysis of Effective Methods for Solving Band Matrix SLAEs after Parabolic Nonlinear PDEs
This paper presents an experimental performance study of implementations of
three different types of algorithms for solving band matrix systems of linear
algebraic equations (SLAEs) after parabolic nonlinear partial differential
equations -- direct, symbolic, and iterative, the former two of which were
introduced in Veneva and Ayriyan (arXiv:1710.00428v2). An iterative algorithm
is presented -- the strongly implicit procedure (SIP), also known as the Stone
method. This method uses the incomplete LU (ILU(0)) decomposition. An
application of the Hotelling-Bodewig iterative algorithm is suggested as a
replacement of the standard forward-backward substitutions. The upsides and the
downsides of the SIP method are discussed. The complexity of all the
investigated methods is presented. Performance analysis of the implementations
is done using the high-performance computing (HPC) clusters "HybriLIT" and
"Avitohol". To that purpose, the experimental setup and the results from the
conducted computations on the individual computer systems are presented and
discussed.Comment: 10 pages, 2 figure
Form factors at strong coupling via a Y-system
We compute form factors in planar N=4 Super Yang-Mills at strong coupling.
Namely we consider the overlap between an operator insertion and 2n gluons.
Through the gauge/string duality these are given by minimal surfaces in AdS
space. The surfaces end on an infinite periodic sequence of null segments at
the boundary of AdS. We consider surfaces that can be embedded in AdS_3. We
derive set of functional equations for the cross ratios as functions of the
spectral parameter. These equations are of the form of a Y-system. The integral
form of the Y-system has Thermodynamics Bethe Ansatz form. The area is given by
the free energy of the TBA system or critical value of Yang-Yang functional. We
consider a restricted set of operators which have small conformal dimension
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