TY  - JOUR
A1  - Grafe, T. Ulmar
A1  - Preininger, Doris
A1  - Sztatecsny, Marc
A1  - Kasah, Rosli
A1  - Dehling, J. Maximilian
A1  - Proksch, Sebastian
A1  - Hödl, Walter
T1  - Multimodal Communication in a Noisy Environment: A Case Study of the Bornean Rock Frog Staurois parvus
JF  - PLoS One
N2  - High background noise is an impediment to signal detection and perception. We report the use of multiple solutions to improve signal perception in the acoustic and visual modality by the Bornean rock frog, Staurois parvus. We discovered that vocal communication was not impaired by continuous abiotic background noise characterised by fast-flowing water. Males modified amplitude, pitch, repetition rate and duration of notes within their advertisement call. The difference in sound pressure between advertisement calls and background noise at the call dominant frequency of 5578 Hz was 8 dB, a difference sufficient for receiver detection. In addition, males used several visual signals to communicate with conspecifics with foot flagging and foot flashing being the most common and conspicuous visual displays, followed by arm waving, upright posture, crouching, and an open-mouth display. We used acoustic playback experiments to test the efficacy-based alerting signal hypothesis of multimodal communication. In support of the alerting hypothesis, we found that acoustic signals and foot flagging are functionally linked with advertisement calling preceding foot flagging. We conclude that S. parvus has solved the problem of continuous broadband low-frequency noise by both modifying its advertisement call in multiple ways and by using numerous visual signals. This is the first example of a frog using multiple acoustic and visual solutions to communicate in an environment characterised by continuous noise.
KW  - call
KW  - dart-poison frog
KW  - animal communication
KW  - auditory masking
KW  - acoustic communication
KW  - anthropogenic noise
KW  - courtship displays
KW  - traffic noise
KW  - higher pitch
KW  - signals
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133718
VL  - 7
IS  - 5
ER  - 
TY  - JOUR
A1  - Audehm, P.
A1  - Schmidt, M.
A1  - Brück, S.
A1  - Tietze, T.
A1  - Gräfe, J.
A1  - Macke, S.
A1  - Schütz, G.
A1  - Goering, E.
T1  - Pinned orbital moments - A new contribution to magnetic anisotropy
JF  - Scientific Reports
N2  - Reduced dimensionality and symmetry breaking at interfaces lead to unusual local magnetic configurations, such as glassy behavior, frustration or increased anisotropy. The interface between a ferromagnet and an antiferromagnet is such an example for enhanced symmetry breaking. Here we present detailed X-ray magnetic circular dichroism and X-ray resonant magnetic reflectometry investigations on the spectroscopic nature of uncompensated pinned magnetic moments in the antiferromagnetic layer of a typical exchange bias system. Unexpectedly, the pinned moments exhibit nearly pure orbital moment character. This strong orbital pinning mechanism has not been observed so far and is not discussed in literature regarding any theory for local magnetocrystalline anisotropy energies in magnetic systems. To verify this new phenomenon we investigated the effect at different temperatures. We provide a simple model discussing the observed pure orbital moments, based on rotatable spin magnetic moments and pinned orbital moments on the same atom. This unexpected observation leads to a concept for a new type of anisotropy energy.
KW  - pinned orbital moments
KW  - ferromagnet
KW  - antiferromagnet
KW  - anisotropy energy
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167727
VL  - 6
IS  - 25517
ER  -