ISSN:0031-9228    

DOI:10.1063/1.2809684

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809686

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Proponents of the standard inflationary model of cosmology breathed a collective sigh of relief when members of the scientific team of NASA's Cosmic Background Explorer described their measurements of the microwave radiation anisotropy at the APS spring meeting. The COBE satellite had provided the data necessary to keep the theories alive. To explain the observation of such structures as galaxies, galactic clusters and the enormous agglomeration of galaxies called the “Great Wall,” those models required some indication that the very early universe contained density fluctuations from which such structures might grow. But the cosmic background radiation, which should reflect any deviations from a uniform density at those formative times, had appeared remarkably homogeneous in its spatial distribution. (SeePHYSICS TODAY, June 1990, page 20.)

ISSN:0031-9228    

DOI:10.1063/1.2809687

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The conventional recipe for a baked Alaska calls for meringue, solid ice cream and a moderate degree of culinary skill. The baked Alaskas recently observed by Peter Schiffer, Douglas Osheroff and coworkers at Stanford University involve the superfluid phases of helium‐3, sample cells with ultrasmooth walls and a sprinkling of cosmic rays. Their results strongly support the “baked Alaska” model that was devised to solve the long‐standing puzzle of how the B phase of superfluid3Hecan possibly nucleate in a sample of A phase. Also, their techniques for the first time allow the study of an anisotropic BCS superfluid in the lowtemperature limit in the absence of a strong magnetic field.

ISSN:0031-9228    

DOI:10.1063/1.2809688

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Through the long‐range force of gravity, mass controls the evolution of the universe. Studies of the internal motion of large, gravitationally bound systems such as galaxies and clusters of galaxies have already shown us, rather convincingly, that the mass in these systems is dominated by some form of matter that is not luminous at any wavelength from radio to x ray. (See the article by Scott Tremaine inPHYSICS TODAY, February, page 28.)

ISSN:0031-9228    

DOI:10.1063/1.881309

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

During the past two decades nuclear magnetic resonance has revolutionized chemistry, biochemistry, biology and, more recently, diagnostic medicine. Nuclear magnetic resonance imaging, or mri as it is commonly called, is fundamentally different from x‐ray‐based techniques in terms of the principles of spatial encoding and mechanisms of signal and contrast generation involved. Mri has a far richer ultimate potential than any other imaging technique known today, and its technology and applications are still far from maturation, which may not occur until early in the 21st century.

ISSN:0031-9228    

DOI:10.1063/1.881310

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The purpose of nuclear physics is to measure properties of specific nuclides and infer from them global properties common to all nuclides. One goal, for example, is to understand nuclear sizes and matter distributions in terms of basic nuclear forces. Another is to understand the variation throughout the periodic table of the dominant quantum states, which are known as the “nuclear shell model” states and are characterized, much as are atomic states, by a principal quantum number and by orbital and total angular momentum quantum numbers. In turn other nuclear phenomena, such as the collective excitations known as giant resonances, can be understood in terms of the shell‐model configurations and basic nuclear parameters.

ISSN:0031-9228    

DOI:10.1063/1.881311

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809689

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809690

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2809691

出版商:AIP    

年代:1992

数据来源: AIP