Daar is vier biljoen mense in die wêreld. Veertig miljoen van hulle is blind. As die verhouding tussen bevolkingsaanwas en blindheid nie verm inder nie, sal die syfer teen die einde van die eeu verdubbel wees. Ten minste 80% van die wêreld se blindheid kom voor in die ontwikkelende lande van A sië, Afrika en Latyns-Am erika. Die Internasionale Agentskap vir die Voorkom ing van Blindheid (I .A ....

A set S of positive integers is avoidable if there exists a partition of the positive integers into two disjoint sets such that no two distinct integers from the same set sum to an element of S. Much previous work has focused on proving the avoidability of very special sets of integers. We vastly broaden the class of avoidable sets by establishing a previously unnoticed connection with the elem...

An interesting culture obtained by limiting dilution is less likely to be monoclonal than a random viable culture. Current practice using limiting dilution to establish monoclonal lines of interesting recombinant DNA or hybridoma-derived organisms overestimates the probability that promising cultures are monoclonal, resulting in inadequate dilutions, with the need for additional subcloning and ...

American relations with ChinaChina are at their lowest point in 50 years. Some say Donald TrumpTrump, has bequeathed Joe BidenBiden, a new Cold War, which they define as intense competition without shooting. But it is not yet and Mr. Trump the sole source of problem.