We prove a re ned version of Shelah's theorem of the Arrow property. Let Cr(A) be the set of all choice functions de ned on the r-element subsets of a nite set A. Then any non-empty proper symmetric subset D of the set Cr(A) has the Arrow property whenever |A| ≥ 5 and r ≥ 3. We also describe all symmetric sets D ⊂ Cr(A) that have the Arrow property if either r = 2, or r = 3 and |A| = 4.

The main route towards populating the string landscape relies on nucleation of “baby universes”. One should however ask whether such babies can resemble the Universe we observe. For they may not have an Arrow of time: even if some of them have basic physical laws essentially identical to those we have discovered, they may have the wrong — insufficiently smooth — initial conditions. We argue tha...

After acute coronary occlusion in primates, the time period during which reperfusion results in significant salvage of reversibly injured myocardium was investigated. In 23 monkeys, the left anterior descending coronary artery was occluded from 1 to 6 h; and in 5 others, occlusion was maintained for the 1-wk study. Unipolar epicardial electrocardiograms were monitored from mapping points on the...

Picture 1. Comparison of chest x-ray and three-dimensional images. A) Posteroanterior chest xray film on admission showed a large mass occupying the right lower-lung field (arrow) with a right-sided aortic arch (arrowhead). B) Three-dimensional image by MDCT clearly showed aneurysms of the right-sided descending thoracic aorta (arrow) with a right-sided aortic arch (arrowhead) and abdominal aor...