Sexual Dimorphism of the Zebra Finch Syrinx Indicates Adaptation for High Fundamental Frequencies in Males

In many songbirds the larger vocal repertoire of males is associated with sexual dimorphism of the vocal control centers and muscles of the vocal organ, the syrinx. However, it is largely unknown how these differences are translated into different acoustic behavior.Here we show that the sound generating structures of the syrinx, the labia and the associated cartilaginous framework, also display sexual dimorphism. One of the bronchial half rings that position and tense the labia is larger in males, and the size and shape of the labia differ between males and females. The functional consequences of these differences were explored by denervating syringeal muscles. After denervation, both sexes produced equally low fundamental frequencies, but the driving pressure generally increased and was higher in males. Denervation strongly affected the relationship between driving pressure and fundamental frequency.The syringeal modifications in the male syrinx, in concert with dimorphisms in neural control and muscle mass, are most likely the foundation for the potential to generate an enhanced frequency range. Sexually dimorphic vocal behavior therefore arises from finely tuned modifications at every level of the motor cascade. This sexual dimorphism in frequency control illustrates a significant evolutionary step towards increased vocal complexity in birds

Development of an Easy-to-Use Spanish Health Literacy Test

OBJECTIVE: The study was intended to develop and validate a health literacy test, termed the Short Assessment of Health Literacy for Spanish-speaking Adults (SAHLSA), for the Spanish-speaking population. STUDY DESIGN: The design of SAHLSA was based on the Rapid Estimate of Adult Literacy in Medicine (REALM), known as the most easily administered tool for assessing health literacy in English. In addition to the word recognition test in REALM, SAHLSA incorporates a comprehension test using multiple-choice questions designed by an expert panel. DATA COLLECTION: Validation of SAHLSA involved testing and comparing the tool with other health literacy instruments in a sample of 201 Spanish-speaking and 202 English-speaking subjects recruited from the Ambulatory Care Center at UNC Health Care. PRINCIPAL FINDINGS: With only the word recognition test, REALM could not differentiate the level of health literacy in Spanish. The SAHLSA significantly improved the differentiation. Item response theory analysis was performed to calibrate the SAHLSA and reduce the instrument to 50 items. The resulting instrument, SAHLSA-50, was correlated with the Test of Functional Health Literacy in Adults, another health literacy instrument, at r = 0.65. The SAHLSA-50 score was significantly and positively associated with the physical health status of Spanish-speaking subjects (p < .05), holding constant age and years of education. The instrument displayed good internal reliability (Cronbach's α = 0.92) and test–retest reliability (Pearson's r = 0.86). CONCLUSIONS: The new instrument, SAHLSA-50, has good reliability and validity. It could be used in the clinical or community setting to screen for low health literacy among Spanish speakers