Proprietary vs. Public Domain Licensing of Software and Research Products

We study the production of knowledge when many researchers or inventors are involved, in a setting where tensions can arise between individual public and private contributions. We first show that without some kind of coordination, production of the public knowledge good (science or research software or database) is sub-optimal. Then we demonstrate that if "lead" researchers are able to establish a norm of contribution to the public good, a better outcome can be achieved, and we show that the General Public License (GPL) used in the provision of open source software is one of such mechanisms. Our results are then applied to the specific setting where the knowledge being produced is software or a database that will be used by academic researchers and possibly by private firms, using as an example a product familiar to economists, econometric software. We conclude by discussing some of the ways in which pricing can ameliorate the problem of providing these products to academic researchers.

Changes in the McGurk Effect Across Phonetic Contexts

To investigate the process underlying audiovisual speech perception, the McGurk illusion was examined across a range of phonetic contexts. Two major changes were found. First, the frequency of illusory /g/ fusion percepts increased relative to the frequency of illusory /d/ fusion percepts as vowel context was shifted from /i/ to /a/ to /u/. This trend could not be explained by biases present in perception of the unimodal visual stimuli. However, the change found in the McGurk fusion effect across vowel environments did correspond systematically with changes in second format frequency patterns across contexts. Second, the order of consonants in illusory combination percepts was found to depend on syllable type. This may be due to differences occuring across syllable contexts in the timecourses of inputs from the two modalities as delaying the auditory track of a vowel-consonant stimulus resulted in a change in the order of consonants perceived. Taken together, these results suggest that the speech perception system either fuses audiovisual inputs into a visually compatible percept with a similar second formant pattern to that of the acoustic stimulus or interleaves the information from different modalities, at a phonemic or subphonemic level, based on their relative arrival times.National Institutes of Health (R01 DC02852

Reliability of single-subject neural activation patterns in speech production tasks

Traditional group fMRI (functional magnetic resonance imaging) analyses are not designed to detect individual differences that may be crucial to better understanding speech disorders. Single-subject research could therefore provide a richer characterization of the neural substrates of speech production in development and disease. Before this line of research can be tackled, however, it is necessary to evaluate whether healthy individuals exhibit reproducible brain activation across multiple sessions during speech production tasks. In the present study, we evaluated the reliability and discriminability of cortical functional magnetic resonance imaging data from twenty neurotypical subjects who participated in two experiments involving reading aloud mono- or bisyllabic speech stimuli. Using traditional methods like the Dice and intraclass correlation coefficients, we found that most individuals displayed moderate to high reliability, with exceptions likely due to increased head motion in the scanner. Further, this level of reliability for speech production was not directly correlated with reliable patterns in the underlying average blood oxygenation level dependent signal across the brain. Finally, we found that a novel machine-learning subject classifier could identify these individuals by their speech activation patterns with 97% accuracy from among a dataset of seventy-five subjects. These results suggest that single-subject speech research would yield valid results and that investigations into the reliability of speech activation in people with speech disorders are warranted.Accepted manuscrip

Marta María Magdalena Huertas, El modelo constitucional norteamericano en los fallos de la Corte Suprema de Justicia de la Nación (1863-1903), Buenos Aires, Instituto de Investigaciones de Historia del Derecho, 2001.

Fil: Santiago, Alfonso (h). Universidad Nacional de Cuyo. Facultad de Filosofía y Letra