ISSN:0031-9228    

DOI:10.1063/1.2408525

出版商:AIP    

年代:1904

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1688051

出版商:AIP    

年代:1904

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1688052

出版商:AIP    

年代:1904

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1688053

出版商:AIP    

年代:1904

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1688056

出版商:AIP    

年代:1904

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2408526

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Last year, considerable skepticism greeted the first experimental reports of a new kind of hadron: a baryon whose combination of charge and flavor could not be made by a triplet of quarks. No fewer than five quarks (one of them an antiquark) would do (see PHYSICSTODAY, September 2003, page 19). Why, the skeptics asked, had no one previously seen this alleged “pentaquark” or, for that matter, any other pentaquark?

ISSN:0031-9228    

DOI:10.1063/1.1688058

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

In 1883, Osborne Reynolds published his landmark paper on the transition from smooth, laminar flow to turbulent flow in cylindrical pipes. Drawing water through a horizontal glass pipe, Reynolds injected a narrow stream of dye and looked for the onset of eddies as he varied the flow velocity and the water viscosity (dependent on water temperature). He found that the transition to turbulence was very sensitive to disturbances and typically occurred above a critical value of about 2000 for the ratio ofUD/&ngr;, whereUis the average (or bulk) velocity,Dis the pipe diameter, and &ngr; is the kinematic viscosity. This ratio, which parameterizes the relative strengths of inertial and viscous forces, is now known as the Reynolds numberRe.

ISSN:0031-9228    

DOI:10.1063/1.1688059

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

On 7 March 1962, what became known as the Ash Wednesday Storm struck the mid‐Atlantic coast of the US. Boosted by a high spring tide, the storm's waves grabbed sand normally out of reach and dumped it in offshore shoals. In Delaware, the storm pushed the shoreline back 80 meters.

ISSN:0031-9228    

DOI:10.1063/1.1688060

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Defeating terrorism and “protecting the homeland” continue to be the focus of the federal budget in fiscal year 2004, with Congress essentially approving a Bush administration budget that is heavily weighted toward defense and security. While the budget includes $127 billion in research and development funding—a $10 billion increase over last year and a record for federal R&D spending—it doesn't change the stagnant state of government funding for much of civilian science.

ISSN:0031-9228    

DOI:10.1063/1.1688061

出版商:AIP    

年代:1904

数据来源: AIP