The dynamics of predation risk assessment: responses of anuran larvae to chemical cues of predators

1.  While the antipredator behaviour of prey has been well studied, little is known about the rules governing the predation risk assessment of prey. In this study, I measured the activity levels of predator-naive green frog ( Rana clamitans ) tadpoles during and after exposures to the chemical cue of predatory larval dragonflies ( Anax spp.). I then used the lengths of the time lags from the end of the cue exposures until the tadpoles returned to a control level of activity as an index of the perceived risk of the tadpoles. 2.  While tadpoles always responded upon exposure to the Anax chemical cue by strongly reducing their activity level, their perceived risk increased asymptotically over time during the initial period of the cue exposure. Tadpoles of all size classes perceived increasing risk in proportion to chemical cue concentration, but the length of time that tadpoles responded during cue exposure and the length of their post-exposure time lags decreased with increasing body mass. 3.  The results suggest that the perceived risk of green frog tadpoles varies over time and does not correspond directly to their behavioural response (i.e. activity level). However, their perceived risk does appear to vary in accordance with the predation risk associated with the Anax chemical cue and the reliability of the information from the cue, and therefore may be predictable.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73939/1/j.1365-2656.2008.01386.x.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/73939/2/JANE_1386_sm_Figs1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/73939/3/JANE_1386_sm_Figs2.pd

Enhanced Recognition of Vocal Emotions in Individuals With Naturally Good Musical Abilities

Music training is widely assumed to enhance several nonmusical abilities, including speech perception, executive functions, reading, and emotion recognition. This assumption is based primarily on cross-sectional comparisons between musicians and nonmusicians. It remains unclear, however, whether training itself is necessary to explain the musician advantages, or whether factors such as innate predispositions and informal musical experience could produce similar effects. Here, we sought to clarify this issue by examining the association between music training, music perception abilities and vocal emotion recognition. The sample (N = 169) comprised musically trained and untrained listeners who varied widely in their musical skills, as assessed through self-report and performance-based measures. The emotion recognition tasks required listeners to categorize emotions in nonverbal vocalizations (e.g., laughter, crying) and in speech prosody. Music training was associated positively with emotion recognition across tasks, but the effect was small. We also found a positive association between music perception abilities and emotion recognition in the entire sample, even with music training held constant. In fact, untrained participants with good musical abilities were as good as highly trained musicians at recognizing vocal emotions. Moreover, the association between music training and emotion recognition was fully mediated by auditory and music perception skills. Thus, in the absence of formal music training, individuals who were “naturally” musical showed musician-like performance at recognizing vocal emotions. These findings highlight an important role for factors other than music training (e.g., predispositions and informal musical experience) in associations between musical and nonmusical domains. (PsycInfo Database Record (c) 2020 APA, all rights reserved

Slow, fast and in between: habitat distribution and behaviour of larvae in nine species of libellulid dragonfly

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72093/1/j.1365-2427.2007.01889.x.pd

Anisotropy parameters of superconducting MgB2_2

Data on macroscopic superconducting anisotropy of MgB$_2$ are reviewed. The data are described within a weak coupling two-gaps anisotropic s-wave model of superconductivity. The calculated ratio of the upper critical fields $\gamma_H=H_{c2,ab}/H_{c2,c}$ increases with decreasing temperature in agreement with available data, whereas the calculated ratio of London penetration depths $\gamma_{\lambda}=\lambda_c/\lambda_{ab}$ decreases to reach $\approx 1.1$ at T=0. Possible macroscopic consequences of $\gamma_{\lambda}\ne\gamma_H$ are discussed.Comment: accepted to Physica C, special MgB2 issu

Influence of decreasing nutrient path length on the development of engineered cartilage

SummaryObjectiveChondrocyte-seeded agarose constructs of 4mm diameter (2.34mm thickness) develop spatially inhomogeneous material properties with stiffer outer edges and a softer central core suggesting nutrient diffusion limitations to the central construct region [Guilak F, Sah RL, Setton LA. Physical regulation of cartilage metabolism. In: Mow VC, Hayes WC, Eds. Basic Orthopaedic Biomechanics, Philadelphia 1997;179–207.]. The effects of reducing construct thickness and creating channels running through the depth of the thick constructs were examined.MethodsIn Study 1, the properties of engineered cartilage of 0.78mm (thin) or 2.34mm (thick) thickness were compared. In Study 2, a single nutrient channel (1mm diameter) was created in the middle of each thick construct. In Study 3, the effects of channels on larger 10mm diameter, thick constructs were examined.ResultsThin constructs developed superior mechanical and biochemical properties than thick constructs. The channeled constructs developed significantly higher mechanical properties vs control channel-free constructs while exhibiting similar glycosaminoglycan (GAG) and collagen content. Collagen staining suggested that channels resulted in a more uniform fibrillar network. Improvements in constructs of 10mm diameter were similarly observed.ConclusionsThis study demonstrated that more homogeneous tissue-engineered cartilage constructs with improved mechanical properties can be achieved by reducing their thickness or incorporating macroscopic nutrient channels. Our data further suggests that these macroscopic channels remain open long enough to promote this enhanced tissue development while exhibiting the potential to refill with cell elaborated matrix with additional culture time. Together with reports that <3mm defects in cartilage heal in vivo and that irregular holes are associated with clinically used osteochondral graft procedures, we anticipate that a strategy of incorporating macroscopic channels may aid the development of clinically relevant engineered cartilage with functional properties

Macroscopic anisotropy in superconductors with anisotropic gaps

It is shown within the weak-coupling model that the macroscopic superconducting anisotropy for materials with the gap varying on the Fermi surface cannot be characterized by a single number, unlike the case of clean materials with isotropic gaps. For clean uniaxial materials, the anisotropy parameter $\gamma (T)$ defined as the ratio of London penetration depths, $\lambda_c/\lambda_{ab}$, is evaluated for all $T$'s. Within the two-gap model of MgB$_2$, $\gamma (T)$ is an increasing function of $T$.Comment: 4 pages, 2 figure

Species-specific responses of planktivorous fish to the introduction of a new piscivore: implications for prey fitness

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75539/1/j.1365-2427.2007.01810.x.pd