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We investigated effects of naturally occurring variation in experience with adult males on development of song and courtship competence in captive juvenile cowbirds. We studied birds in groups housed in large outdoor aviaries that allowed birds to regulate access to social stimulation. In two aviaries, we housed juvenile males and females either with or without adult males. Birds remained in these conditions from September 1999 through their breeding season. We documented social and vocal development of juvenile males in the two aviaries by measuring social assortment and patterns and frequencies of their song interactions. We then brought the juveniles from the two aviaries together to compete against each other for access to females. In addition, we recorded juveniles' songs four times over the study and played back their breeding season songs to females in sound-attenuating chambers to measure the effectiveness of songs in eliciting copulatory responses from the females. Compared to juvenile males housed with adult males, juvenile males housed without adult males developed atypical behavior patterns. They (1) displayed little intrasexual aggression or near-neighbor associations and (2) exhibited different patterns of courtship and copulation, but (3) were as successful at competing for copulations. Furthermore, they developed stereotyped songs sooner and developed more potent breeding season songs. These different outcomes could not be traced to one variable but to a cascade of effects involving diverging patterns of song acquisition and social interaction. The patterns of social skills that emerged indicate considerable plasticity in the mechanisms underlying acquisition of courtship competence. [ABSTRACT FROM AUTHOR]

Determination of the cardiorespiratory phase of the heart has numerous applications during cardiac imaging. In this article we propose a novel view-angle independent near-real time cardiorespiratory motion gating and coronary sinus (CS) catheter tracking technique for x-ray fluoroscopy images that are used to guide cardiac electrophysiology procedures. The method is based on learning CS catheter motion using principal component analysis and then applying the derived motion model to unseen images taken at arbitrary projections, using the epipolar constraint. This method is also able to track the CS catheter throughout the x-ray images in any arbitrary subsequent view. We also demonstrate the clinical application of our model on rotational angiography sequences. We validated our technique in normal and very low dose phantom and clinical datasets. For the normal dose clinical images we established average systole, end-expiration and end-inspiration gating success rates of 100%, 85.7%, and 92.3%, respectively. For very low dose applications, the technique was able to track the CS catheter with median errors not exceeding 1 mm for all tracked electrodes. Average gating success rates of 80.3%, 71.4%, and 69.2% were established for the application of the technique on clinical datasets, even with a dose reduction of more than 10 times. In rotational sequences at normal dose, CS tracking median errors were within 1.2 mm for all electrodes, and the gating success rate was 100%, for view angles from RAO 90° to LAO 90°. This view-angle independent technique can extract clinically useful cardiorespiratory motion information using x-ray doses significantly lower than those currently used in clinical practice. [ABSTRACT FROM AUTHOR]