Effects of the repeated administration of adenosine and heparin on myocardial perfusion in patients with chronic stable angina pectoris.

The mechanism by which ischemia stimulates angiogenesis is unknown. Adenosine is released during myocardial ischemia and may be a mediator of this process. Experimental data suggest that heparin may enhance this effect.

The control of carrier frequency in cricket calls: a refutation of the subalar-tegminal resonance/auditory feedback model.

The subalar-tegminal resonance/auditory feedback hypothesis attempts to explain how crickets control the carrier frequency (f(C)), the loudness and the spectral purity of their calls. This model contrasts with the 'clockwork cricket' or escapement model by proposing that f(C) is not controlled by the resonance of the cricket's radiators (the harps) but is instead controlled neurally. It suggests that crickets are capable of driving their harps to vibrate at any frequency and that they use a tunable Helmholtz-like resonator consisting of the tegmina and the air within the subalar space to amplify and filter the f(C).

Advances in cardiopulmonary resuscitation.

Approximately 500,000 deaths per year are the results of coronary artery disease. Many of these deaths can be prevented by prompt action to provide basic cardiopulmonary resuscitation (CPR) and early defibrillation. In recent years, a number of new CPR methods have been developed in hopes of improving cardiac output in an arrest situation.