Search results for "Playback"

Can video playback provide social information for foraging blue tits?

2017

Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits (Cyanistes caeruleus) videos of demonstrators discovering palatable or aversive prey (injected with bittertasting Bitrex) from coloured feeding cups. First we quantify variation in demonstrators’ responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show tha…

Estimating the abundance of burrow-nesting species through the statistical analysis of combined playback and visual surveys

2016

The effect of social information from live demonstrators compared to video playback on blue tit foraging decisions.

2019

Video playback provides a promising method to study social interactions, and the number of video playback experiments has been growing in recent years. Using videos has advantages over live individuals as it increases the repeatability of demonstrations, and enables researchers to manipulate the features of the presented stimulus. How observers respond to video playback might, however, differ among species, and the efficacy of video playback should be validated by investigating if individuals’ responses to videos are comparable to their responses to live demonstrators. Here, we use a novel foraging task to compare blue tits’ (Cyanistes caeruleus) responses to social information from a live …

Recognition of familiarity on the basis of howls: a playback experiment in a captive group of wolves

2015

Playback experiments were conducted with a pack of captive Iberian wolves. We used a habituation–discrimination paradigm to test wolves’ ability to discriminate howls based on: (1) artificial manipulation of acoustic parameters of howls and (2) the identity of howling individuals. Manipulations in fundamental frequency and frequency modulation within the natural range of intra-individual howl variation did not elicit dishabituation, while manipulation of modulation pattern did produce dishabituation. With respect to identity, across trials wolves habituated to unfamiliar howls by a familiar wolf (i.e., no direct contact, but previous exposure to howls by this wolf), but not to unfamiliar ho…

Intrinsic electrical conductivity of nanostructured metal-organic polymer chains

2012

One-dimensional conductive polymers are attractive materials because of their potential in flexible and transparent electronics. Despite years of research, on the macro- and nano-scale, structural disorder represents the major hurdle in achieving high conductivities. Here we report measurements of highly ordered metal-organic nanoribbons, whose intrinsic (defect-free) conductivity is found to be 104 S m−1, three orders of magnitude higher than that of our macroscopic crystals. This magnitude is preserved for distances as large as 300 nm. Above this length, the presence of structural defects (~ 0.5%) gives rise to an inter-fibre-mediated charge transport similar to that of macroscopic crysta…

Topological insulators and thermoelectric materials

2012

Topological insulators (TIs) are a new quantum state of matter which have gapless surface states inside the bulk energy gap. Starting with the discovery of two dimensional TIs, the HgTe-based quantum wells, many new topological materials have been theoretically predicted and experimentally observed. Currently known TI materials can possibly be classified into two families, the HgTe family and the Bi2Se family. The signatures found in the electronic structure of a TI also cause these materials to be excellent thermoelectric materials. On the other hand, excellent thermoelectric materials can be also topologically trivial. Here we present a short introduction to topological insulators and the…

Critical behavior in quantum spin chains with composite spin

1989

Composite spin models are constructed such that, by varying two parameters, they interpolate between the spin-(1/2 antiferromagnetic Heisenberg chain and a number of spin-1 models. These include the usual Heisenberg model, the integrable spin-1 model, and the model with an exact valence-bond ground state. Finite-chain calculations are performed on the composite spin model to study its criticality, and to find if the integrable spin-1 model is a multicritical point with a finite gap generated away from it. We find indications for an extended gapless region.

Fast timing and trigger Cherenkov detector for collider experiments

2016

Analysis of fast timing and trigger Cherenkov detector's design for its use in collider experiments is presented. Several specific requirements are taken into account - necessity of the radiator's placement as close to the beam pipe as possible along with the requirement of gapless (solid) radiator's design. Characteristics of the Cherenkov detector's laboratory prototype obtained using a pion beam at the CERN Proton Synchrotron are also presented, showing the possibility of obtaining sufficiently high geometrical efficiency along with good enough time resolution (50 ps sigma).

Antiferromagnetic Topological Insulator with Nonsymmorphic Protection in Two Dimensions

2019

The recent demonstration of topological states in antiferromagnets (AFMs) provides an exciting platform for exploring prominent physical phenomena and applications of antiferromagnetic spintronics. A famous example is the AFM topological insulator (TI) state, which, however, was still not observed in two dimensions. Using a tight-binding model and first-principles calculations, we show that, in contrast to previously observed AFM topological insulators in three dimensions, an AFM TI can emerge in two dimensions as a result of a nonsymmorphic symmetry that combines the twofold rotation symmetry and half-lattice translation. Based on the spin Chern number, Wannier charge centers, and gapless …

Topological Hamiltonian as an exact tool for topological invariants

2012

We propose the concept of `topological Hamiltonian' for topological insulators and superconductors in interacting systems. The eigenvalues of topological Hamiltonian are significantly different from the physical energy spectra, but we show that topological Hamiltonian contains the information of gapless surface states, therefore it is an exact tool for topological invariants.