Auditory feedback is important for the control of voice fundamental frequency (F0). In the present study we used neuroimaging to identify regions of the brain responsible for sensory control of the voice. We used a pitch-shift paradigm where subjects respond to an alteration, or shift, of voice pitch auditory feedback with a reflexive change in F0. To determine the neural substrates involved in these audio-vocal responses, subjects underwent fMRI scanning while vocalizing with or without pitch-shifted feedback. The comparison of shifted and unshifted vocalization revealed activation bilaterally in the superior temporal gyrus (STG) in response to the pitch shifted feedback. We hypothesize that the STG activity is related to error detection by auditory error cells located in the superior temporal cortex and efference copy mechanisms whereby this region is responsible for the coding of a mismatch between actual and predicted voice F0.

No abstract

No abstract

We study the stellar populations of a sample of 14 elliptical galaxies in the Virgo cluster. Using spectra with high signal‐to‐noise ratio (S/N ≳ 100 Å−1) we propose an alternative approach to the standard side‐band method to measure equivalent widths (EWs). Our boosted median continuum is shown to map the EWs more robustly than the side‐band method, minimizing the effect from neighbouring absorption lines and reducing the uncertainty at a given S/N. Our newly defined line strengths are more successful at disentangling the age–metallicity degeneracy. We concentrate on Balmer lines (Hβ, Hγ, Hδ), the G band and the combination [MgFe] as the main age and metallicity indicators. We go beyond the standard comparison of the observations with simple stellar populations (SSPs) and consider four different models to describe the star formation histories, either with a continuous star formation rate or with a mixture of two different SSPs. These models improve the estimates of the more physically meaningful mass‐weighted ages. Composite models are found to give more consistent fits among individual line strengths and agree with an independent estimate using the spectral energy distribution. A combination of age‐ and metallicity‐sensitive spectral features allows us to constrain the average age and metallicity. For a Virgo sample of elliptical galaxies our age and metallicity estimates correlate well with stellar mass or velocity dispersion, with a significant threshold around 5 × 1010 M⊙ above which galaxies are uniformly old and metal rich. This threshold is reminiscent of the one found by Kauffmann et al. in the general population of Sloan Digital Sky Survey galaxies at a stellar mass 3 × 1010 M⊙. In a more speculative way, our models suggest that it is formation epoch and not formation time‐scale what drives the mass–age relationship of elliptical galaxies.

A microcantilever with an integrated piezoelectric film is demonstrated as a mercury vapor detector. The cantilever is self-sensing and self-actuating, and therefore does not need alignment of an external, optical detection system. This gives the new sensor system an advantage in array applications. Mercury vapor, when adsorbed onto gold on the cantilever, causes the stiffness, and therefore the natural frequency, of the cantilever to increase as a result of mercury gold amalgamation. This shift is detected using the piezoelectric portion of the cantilever in conjunction with a bridge circuit and amplifier. A mercury concentration of 93 ppb in nitrogen is detected.