In-Air Evoked Potential Audiometry of Grey Seals (Halichoerus grypus) from the North and Baltic Seas

In-air anthropogenic sound has the potential to affect grey seal (Halichoerus grypus) behaviour and interfere with acoustic communication. In this study, a new method was used to deliver acoustic signals to grey seals as part of an in-air hearing assessment. Using in-ear headphones with adapted ear inserts allowed for the measurement of auditory brainstem responses (ABR) on sedated grey seals exposed to 5-cycle (2-1-2) tone pips. Thresholds were measured at 10 frequencies between 1–20 kHz. Measurements were made using subcutaneous electrodes on wild seals from the Baltic and North Seas. Thresholds were determined by both visual and statistical approaches (single point F-test) and good agreement was obtained between the results using both methods. The mean auditory thresholds were ≤40 dB re 20 µPa peak equivalent sound pressure level (peSPL) between 4–20 kHz and showed similar patterns to in-air behavioural hearing tests of other phocid seals between 3 and 20 kHz. Below 3 kHz, a steep reduction in hearing sensitivity was observed, which differed from the rate of decline in sensitivity obtained in behavioural studies on other phocids. Differences in the rate of decline may reflect influence of the ear inserts on the ability to reliably transmit lower frequencies or interference from the structure of the distal end of the ear canal

Microwave Spectroscopy of Thermally Excited Quasiparticles in YBa_2Cu_3O_{6.99}

We present here the microwave surface impedance of a high purity crystal of $YBa_2Cu_3O_{6.99}$ measured at 5 frequencies between 1 and 75 GHz. This data set reveals the main features of the conductivity spectrum of the thermally excited quasiparticles in the superconducting state. Below 20 K there is a regime of extremely long quasiparticle lifetimes, due to both the collapse of inelastic scattering below $T_c$ and the very weak impurity scattering in the high purity $BaZrO_3$-grown crystal used in this study. Above 20 K, the scattering increases dramatically, initially at least as fast as $T^4$.Comment: 13 pages with 10 figures. submitted to Phys Rev

Risk-taking, delay discounting, and time perspective in adolescent gamblers: an experimental study

Previous research has demonstrated that adult pathological gamblers (compared to controls) show risk-proneness, foreshortened time horizon, and preference for immediate rewards. No study has ever examined the interplay of these factors in adolescent gambling. A total of 104 adolescents took part in the research. Two equal-number groups of adolescent non-problem and problem gamblers, defined using the South Oaks Gambling Screen-Revised for Adolescents (SOGS-RA), were administered the Balloon Analogue Risk Task (BART), the Consideration of Future Consequences (CFC-14) Scale, and the Monetary Choice Questionnaire (MCQ). Adolescent problem gamblers were found to be more risk-prone, more oriented to the present, and to discount delay rewards more steeply than adolescent non-problem gamblers. Results of logistic regression analysis revealed that BART, MCQ, and CFC scores predicted gambling severity. These novel finding provides the first evidence of an association among problematic gambling, high risk-taking proneness, steep delay discounting, and foreshortened time horizon among adolescents. It may be that excessive gambling induces shortsighted behaviors that, in turn, facilitate gambling involvement

Effects of pile-driving on harbour porpoises (Phocoena phocoena) at the first offshore wind farm in Germany

The first offshore wind farm ‘alpha ventus’ in the German North Sea was constructed north east of Borkum ReefGround approximately 45 km north off the German coast in 2008 and 2009 using percussive piling for the foundationsof 12 wind turbines. Visual monitoring of harbour porpoises was conducted prior to as well as during construction andoperation by means of 15 aerial line transect distance sampling surveys, from 2008 to 2010. Static acoustic monitoring(SAM) with echolocation click loggers at 12 positions was performed additionally from 2008 to 2011. SAM deviceswere deployed between 1 and 50 km from the centre of the wind farm. During aerial surveys, 18 600 km of transectlines were covered in two survey areas (10 934 and 11 824 km2) and 1392 harbour porpoise sightings were recorded.Lowest densities were documented during the construction period in 2009. The spatial distribution pattern recorded ontwo aerial surveys three weeks before and exactly during pile-driving points towards a strong avoidance response within20 km distance of the noise source. Generalized additive modelling of SAM data showed a negative impact ofpile-driving on relative porpoise detection rates at eight positions at distances less than 10.8 km. Increased detectionrates were found at two positions at 25 and 50 km distance suggesting that porpoises were displaced towards thesepositions. A pile-driving related behavioural reaction could thus be detected using SAM at a much larger distance than apure avoidance radius would suggest. The first waiting time (interval between porpoise detections of at least 10 min),after piling started, increased with longer piling durations. A gradient in avoidance, a gradual fading of the avoidancereaction with increasing distance from the piling site, is hence most probably a product of an incomplete displacementduring shorter piling events