Theoretical aspects of the study of top quark properties

We review some recent theoretical progresses towards the determination of the top-quark couplings beyond the standard model. We briefly introduce the global effective field theory approach to the top-quark production and decay processes, and discuss the most useful observables to constrain the deviations. Recent improvements with a focus on QCD corrections and corresponding tools are also discussed.Comment: 8 pages, 6 figures. Based on plenary talk given at LHCP2017, Shanghai, 15-20 May 201

Nocturnal resting behaviour in urban great tits and its relation to anthropogenic disturbance and microclimate

The ecological novelty of urbanisation poses many challenges to animals. We investigated whether anthropogenic disturbance (artificial light at night and noise) and abiotic factors in cities (temperature and humidity) predict nocturnal activity and rest in free-living urban great tits (Parus major). Our study is the first to relate nocturnal rest in wild birds to levels of noise pollution during the night, an issue that has been shown to be particularly damaging to human health. Unlike previous work on nocturnal behaviour of urban birds, we considered the combined effect of anthropogenic disturbance and urban microclimate to acknowledge that the umwelt of an animal is composed of multiple environmental variables. Using infrared cameras, we observed the nocturnal resting behaviour as a proxy for sleep in 17 birds in nest boxes deployed across the city of Munich, Germany. Although we found marked differences in resting behaviour between individuals, this variation was not related to the measured environmental factors. This finding contrasts earlier studies that reported nocturnal resting behaviour of birds to vary with temperature and light exposure. Although we did not find evidence that urban environmental factors disrupt resting behaviour in great tits, their sleep might still be impaired by the anthropogenic disturbances. To elucidate this issue, further studies are necessary that, for instance, measure brain activity

Calls of Manx shearwater Puffinus puffinus contain individual signatures

Vocalisations are widely used to signal behavioural intention in animal communication, but may also carry acoustic signatures unique to the calling individual. Here, we used acoustic analysis to confirm that Manx shearwater Puffinus puffinus calls carry individual signatures, and discerned which features made the calls individual. Manx shearwater are nocturnal seabirds that breed in dense colonies, where they must recognize and locate mates among thousands of conspecifics calling in the dark. There is evidence for mate vocal recognition in two shearwater species, but quantitative data on the vocalisations are lacking. We elicited vocal responses to playback of conspecific calls in Manx shearwaters, and measured spectral and temporal parameters of the calls. We then applied linear discriminant analysis with leave-one-out cross-validation and could confirm the presence of individual vocal signatures. We then calculated among-individual repeatability of 34 features describing the vocalisation to determine the extent to which these features may contribute to individual signature coding. We found that calls cluster by individual in both temporal and spectral characteristics, suggesting these traits are contributing to Manx shearwaters' unique call signatures

Traffic noise disrupts vocal development and suppresses immune function

Noise pollution has been linked to learning and language deficits in children, but the causal mechanisms connecting noise to cognitive deficiencies remain unclear because experimental models are lacking. Here, we investigated the effects of noise on birdsong learning, the primary animal model for vocal learning and speech development in humans. We found that traffic noise exposure retarded vocal development and led to learning inaccuracies. In addition, noise suppressed immune function during the sensitive learning period, indicating that it is a potent stressor for birds, which is likely to compromise their cognitive functions. Our results provide important insights into the consequences of noise pollution and pave the way for future studies using birdsong as an experimental model for the investigation of noise-induced learning impairments

Traffic noise exposure depresses plasma corticosterone and delays offspring growth in breeding zebra finches.

The impact of human activity on the acoustic environment is overwhelming, with anthropogenic noise reaching even remote areas of the planet. The World Health Organization has identified noise pollution as one of the leading environmental health risks in humans, and it has been linked to a myriad of short- and long-term health effects in exposed individuals. However, less is known about the health effects of anthropogenic noise exposure on animals. We investigated long- and short-term effects of traffic noise on zebra finches breeding in small communal aviaries, using a repeated measures design. Birds bred in both noise and no-noise conditions, and we measured baseline plasma glucocorticoid levels before, during and after breeding. In addition, we assayed immune function, measured reproductive success and offspring growth and compared rates of extra-pair paternity of breeding adults. Breeding birds had significantly lower baseline plasma corticosterone levels when exposed to traffic noise than when they were not exposed to noise playback. In addition, the nestlings reared during noise exposure were lighter than nestlings of the same parents when breeding in control conditions. Our results suggest that traffic noise poses a more severe hurdle to birds at more vulnerable stages of their life history, such as during reproductive events and ontogeny. While chronic exposure to traffic noise in our birds did not, by itself, prove to be a sufficient stressor to cause acute effects on health or reproductive success in exposed individuals, it did result in disruptions to normal glucocorticoid profiles and delayed offspring growth. However, animals living in urban habitats are exposed to a multitude of anthropogenic disturbances, and it is likely that even species that appear to be thriving in noisy environments may suffer cumulative effects of these multiple disturbances that may together impact their fitness in urban environments

Lombard effect onset times reveal the speed of vocal plasticity in a songbird

Animals that use vocal signals to communicate often compensate for interference and masking from background noise by raising the amplitude of their vocalisations. This response has been termed the Lombard effect. However, despite more than a century of research, little is known how quickly animals can adjust the amplitude of their vocalisations after the onset of noise. The ability to respond quickly to increases in noise levels would allow animals to avoid signal masking and ensure their calls continue to be heard, even if they are interrupted by sudden bursts of high-amplitude noise. We tested how quickly singing male canaries (Serinus canaria) exhibit the Lombard effect by exposing them to short playbacks of white noise and measuring the speed of their responses. We show that canaries exhibit the Lombard effect in as little as 300 ms after the onset of noise and are also able to increase the amplitude of their songs mid-song and mid-phrase without pausing. Our results demonstrate high vocal plasticity in this species and suggest that birds are able to adjust the amplitude of their vocalisations very rapidly to ensure they can still be heard even during sudden changes in background noise levels

Traffic noise drowns out great tit alarm calls

Anthropogenic noise is one of the fastest growing and most ubiquitous types of environmental pollution and can impair acoustic communication in a variety of animals [1]. Recent research has shown that birds can adjust acoustic parameters of their sexual signals (songs) in noisy environments 2, 3, yet we know little about other types of vocalizations. Anti-predator signals contain subtle information that is critical for avoiding predation 4, 5, and failure to detect these calls 6, 7 as a result of anthropogenic noise pollution could have large fitness consequences by negatively impacting survival. We investigated whether traffic noise impacts both the production and perception of avian alarm calls using a combination of lab and field experiments with great tits (Parus major), a songbird that frequently inhabits noise-polluted environments. In response to experimental noise manipulation in controlled laboratory conditions, great tits increased the amplitude, but not the frequency parameters, of their mobbing alarm calls (hereafter ‘alarm calls’). Playback experiments conducted in the wild indicate that current levels of road traffic noise mask alarm calls, impeding the ability of great tits to perceive these critical signals. These results show that, despite the vocal adjustments used to compensate for anthropogenic noise, great tits are not able to restore the active space of their calls in even moderately noisy environments. Consequently, birds are likely to suffer from increased predation risk under noise, with likely effects on their behaviour, populations, and community dynamics in noise-polluted areas

Motor mechanisms of a vocal mimic: implications for birdsong production.

The diverse vocal performances of oscine songbirds are produced by the independent but coordinated patterns of activity in muscles controlling separate sound generators on the left and right sides of their duplex vocal organ, the syrinx. Species with different song styles use the two sides of their syrinx in different ways to produce their species-typical songs. Understanding how a vocal mimic copies another species' song may provide an insight into whether there are alternative motor mechanisms for generating the model's song and what parts of his song are most difficult to produce. We show here that when a vocal mimic, the northern mockingbird, accurately copies the song of another species it also uses the vocal motor pattern employed by the model species. Deviations from the model's production mechanism result in predictable differences in the mockingbird's song. Species-specific acoustic features of the model seem most difficult to copy, suggesting that they have been exposed to the strongest selective pressure to maximize their performance