1,399 research outputs found
Chameleons with Field Dependent Couplings
Certain scalar-tensor theories exhibit the so-called chameleon mechanism,
whereby observational signatures of scalar fields are hidden by a combination
of self-interactions and interactions with ambient matter. Not all
scalar-tensor theories exhibit such a chameleon mechanism, which has been
originally found in models with inverse power run-away potentials and field
independent couplings to matter. In this paper we investigate field-theories
with field-dependent couplings and a power-law potential for the scalar field.
We show that the theory indeed is a chameleon field theory. We find the
thin-shell solution for a spherical body and investigate the consequences for
E\"ot-Wash experiments, fifth-force searches and Casimir force experiments.
Requiring that the scalar-field evades gravitational tests, we find that the
coupling is sensitive to a mass-scale which is of order of the Hubble scale
today.Comment: 17 pages, 20 figure
Cross-modal perception of identity by sound and taste in bottlenose dolphins
While studies have demonstrated concept formation in animals, only humans are known to label concepts to use them in mental simulations or predictions. To investigate whether other animals use labels comparably, we studied cross-modal, individual recognition in bottlenose dolphins (Tursiops truncatus) that use signature whistles as labels for conspecifics in their own communication. First, we tested whether dolphins could use gustatory stimuli and found that they could distinguish between water and urine samples, as well as between urine from familiar and unfamiliar individuals. Then, we paired playbacks of signature whistles of known animals with urine samples from either the same dolphin or a different, familiar animal. Dolphins investigated the presentation area longer when the acoustic and gustatory sample matched than when they mismatched. This demonstrates that dolphins recognize other individuals by gustation alone and can integrate information from acoustic and taste inputs indicating a modality independent, labeled concept for known conspecifics
Cross-modal perception of identity by sound and taste in bottlenose dolphins
Funding: The study was supported by a Marie Skłodowska-Curie fellowship of the European Commission, grant number 661214 (J.N.B. and V.M.J.)While studies have demonstrated concept formation in animals, only humans are known to label concepts to use them in mental simulations or predictions. To investigate whether other animals use labels comparably, we studied cross-modal, individual recognition in bottlenose dolphins (Tursiops truncatus) that use signature whistles as labels for conspecifics in their own communication. First, we tested whether dolphins could use gustatory stimuli and found that they could distinguish between water and urine samples, as well as between urine from familiar and unfamiliar individuals. Then, we paired playbacks of signature whistles of known animals with urine samples from either the same dolphin or a different, familiar animal. Dolphins investigated the presentation area longer when the acoustic and gustatory sample matched than when they mismatched. This demonstrates that dolphins recognize other individuals by gustation alone and can integrate information from acoustic and taste inputs indicating a modality independent, labeled concept for known conspecifics.Publisher PDFPeer reviewe
Automatic structures for semigroup constructions
We survey results concerning automatic structures for semigroup
constructions, providing references and describing the corresponding automatic
structures. The constructions we consider are: free products, direct products,
Rees matrix semigroups, Bruck-Reilly extensions and wreath products.Comment: 22 page
Magnetocaloric effect in nano- and polycrystalline manganite
samples were prepared in nano- and polycrystalline
forms by sol-gel and solid state reaction methods, respectively, and
structurally characterized by synchrotron X-ray diffraction. The magnetic
properties determined by ac susceptibility and dc magnetization measurements
are discussed. The magnetocaloric effect in this nanocrystalline manganite is
spread over a broader temperature interval than in the polycrystalline case.
The relative cooling power of the poly- and nanocrystalline manganites is used
to evaluate a possible application for magnetic cooling below room temperature.Comment: 6 pages, 5 (double) figures, 1 table, 16 references; submitted to
Appl. Phys.
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