ISSN:0031-9228    

DOI:10.1063/1.3071130

出版商:AIP    

年代:1972

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3071131

出版商:AIP    

年代:1972

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3071132

出版商:AIP    

年代:1972

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3071133

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

In chemically reacting systems at equilibrium, forward and backward reactions proceed at statistically equal rates, so that the average properties of the system are time independent. However, a series of instantaneous microscopic analyses of the system is expected to reveal recurring random concentration fluctuations about the equilibrium state. Until recently no one had directly measured the rates of fluctuation relaxation by the mechanism of chemical reaction, but now Douglas Magde, Elliott Elson and Watt Webb of Cornell University have seen the thermodynamic concentration fluctuations that reflect the dynamic balance of chemical reactions at equilibrium. They have studied the binding between DNA and the dye ethidium bromide (EtBr), which form a strongly fluorescing complex, and they were able to determine the chemical rate constants, the diffusion coefficients and the coupling between the two by observing fluctuations of the fluorescent intensity.

ISSN:0031-9228    

DOI:10.1063/1.3071135

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The long‐lived K‐meson may decay according to predictions after all. Last year, experiments at the Berkeley Bevatron had failed to find evidence of the reactionKL0←&mgr;++&mgr;−.Accepted theoretical estimates of the ratio of this decay to all other decays (the branching ratio) give a lower bound of about6×10−9,but the Berkeley group established an upper limit of about1.8×10−9,with a 90&percent; confidence level, causing some theorists to question such basic ideas as the nature of muon interactions, the idea that CP is conserved in the decay and even the principles of unitarity (probability conservation) and quantum electrodynamics (seePHYSICS TODAY, July 1971, page 13).

ISSN:0031-9228    

DOI:10.1063/1.3071136

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

In nuclear‐magnetic‐resonance work, the detection of broad lines such as those from solid samples has usually been done by observing a pulse in a radiofrequency pickup coil while carrying out a procedure known as “adiabatic fast passage.” A new technique, in which detection during adiabatic fast passage is by a Josephson‐junction magnetometer, does the same job but with considerably less radiofrequency power.

ISSN:0031-9228    

DOI:10.1063/1.3071137

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The People's Republic of China has made remarkable progress in many aspects of applied physics. This was the conclusion drawn by seven physicists from the United States who recently visited China and then discussed their observations with us. They saw the production of integrated circuits, controlled‐fusion experiments, a superconducting gravimeter, telescopes, a variety of scientific instruments—all produced in China. The US visitors generally got the impression that China was concentrating very much on applications, rather than basic research. And they found a society‐wide attempt to make the higher‐education system more democratic.

ISSN:0031-9228    

DOI:10.1063/1.3071138

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Cosmic numbers have intrigued modern cosmologists ever since puzzling coincidences were first noticed between some of the large dimensionless constants. Here I will try to show not only that these numbers are interesting, but also that they are possibly important to our understanding of the physical world. Have the coincidences always existed or is it merely fortuitous that they occur at the present stage of evolution of the universe?

ISSN:0031-9228    

DOI:10.1063/1.3071139

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We have seen that the formation and maintenance of self‐organizing systems are compatible with the laws of physical chemistry. We must now confront this idea with the major problem of biology: How did biological systems arise?

ISSN:0031-9228    

DOI:10.1063/1.3071140

出版商:AIP    

年代:1972

数据来源: AIP