ISSN:0031-9228    

DOI:10.1063/1.2408449

出版商:AIP    

年代:1902

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1461316

出版商:AIP    

年代:1902

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1461317

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The high‐temperature copper‐oxide superconductors, which offer resistance‐free current flow at temperatures extending well above 100 K, are formed by doping certain copper‐oxide compounds or by adding excess oxygen to them. The parent compounds—all antiferromagnetic insulators—couldn't be more different from their superconducting offspring: Magnetism and superconductivity are generally antithetical. Yet it's hard to deny one's heritage. Many theoretical and experimental studies of high‐temperature superconducting materials have turned up hints of coexisting magnetism, especially in weakly doped materials, where stronger parental influence is to be expected. But left unanswered are such questions as whether the magnetic phase competes or cooperates with the superconductivity, and whether the two phases coexist microscopically or form spatially separate phases.

ISSN:0031-9228    

DOI:10.1063/1.1461319

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

In the molecular world of chemical reactions and conformational changes in biological and other molecules, events often happen on time scales from hundreds to thousands of femtoseconds—the typical period of molecular vibrations. Femtochemistry (described in PHYSICSTODAY, December 1999, page 19) uses ultrashort laser pulses, only a few tens of femtoseconds in duration, to probe electronic changes on such time scales. From these experiments, dynamics information can be extracted. But to obtain direct structural information, one needs a probe whose wavelength matches the angstrom scale of interatomic spacing: x rays are a prime candidate (see the article by Eric Galburt and Barry Stoddard in PHYSICSTODAY, July 2001, page 33).

ISSN:0031-9228    

DOI:10.1063/1.1461320

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

A recent corrective paper by particle theorists Masashi Hayakawa (KEK, Tsukuba, Japan) and Toichiro Kinoshita (Cornell University) is something of a cautionary tale. Since the mid‐1980s, Kinoshita and various colleagues have been laboring to calculate the anomalous magnetic moment of the muon(&agr;&mgr;)from the standard model of particle theory with ever greater precision. The task has taken on particular urgency in the past year, as the pioneering Brookhaven experiment led by Vernon Hughes and Lee Roberts began to improve on earlier measurements of&agr;&mgr;by more than an order of magnitude.

ISSN:0031-9228    

DOI:10.1063/1.1461321

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

“The National Virtual Observatory is neither national, nor virtual, nor an observatory,” says George Djorgovski, a Caltech astronomy professor who is involved in developing the NVO, one of a half dozen or so such projects worldwide. The emerging virtual observatories aim to handle the humongous datasets that are proliferating in astronomy and will have built‐in software tools for people to mine and query data across archives. Eventually, the various projects will be knit together so that ground‐ and space‐based astronomy archives from around the world are linked and accessible to all.

ISSN:0031-9228    

DOI:10.1063/1.1461322

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

When President Bush released his 2002 budget request early last April, proposed science funding was so heavily weighted toward medical and defense research that most other R&D agencies considered themselves fortunate to just stay even with inflation. House Science Committee Chairman Sherwood Boehlert (R‐N.Y.), said the science funding numbers were so bad that NSF should be read “not sufficient funds” instead of “National Science Foundation.”

ISSN:0031-9228    

DOI:10.1063/1.1461323

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

When John Marburger became the director of the Office of Science and Technology Policy (OSTP) on 23 October, his appointment was greeted with both enthusiasm and skepticism in the science community. Marburger, the respected director of Brookhaven National Laboratory before coming to Washington, was considered a good choice for the job by most political observers, including several past presidential science advisers. The concern wasn't with Marburger, but with President Bush, who had left the OSTP position vacant for nearly six months.

ISSN:0031-9228    

DOI:10.1063/1.1461324

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

After dragging its feet for years, the UK is joining the European Southern Observatory in July. The move will give the country's astronomers access to the Very Large Telescope (VLT) and ESO's other facilities in Chile (see Physics Today, September 2000, page 55). The UK will be ESO's 10th member state.

ISSN:0031-9228    

DOI:10.1063/1.4761830

出版商:AIP    

年代:1902

数据来源: AIP