ISSN:0031-9228    

DOI:10.1063/1.2408490

出版商:AIP    

年代:1902

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1522190

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Three summers ago, much attention was paid to a search for new super‐heavy nuclei at the Lawrence Berkeley National Laboratory's 88‐inch cyclotron. In June 1999, the LBNL heavy‐element search team announced the discovery of elements 116 and 118 (see PHYSICSTODAY, August 1999, page 17). In recent weeks, that experiment has once again become the focus of much attention—but now, alas, for a sadder reason.

ISSN:0031-9228    

DOI:10.1063/1.1522199

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The interplay between the nuclear forces and the electromagnetic force determines whether a given combination of protons and neutrons can stay together long enough to be called a nucleus. Even then, some nuclei are sufficiently unstable that, sooner or later, they undergo fission or decay. It stands to reason that a proton‐rich nucleus might strive to shed a few protons. Indeed, back in 1960, Vitalii Goldanskii predicted that proton‐rich nuclei having even values of atomic numberZcould decay by emitting two protons. Iron‐45 was among the rare candidates in which Goldanskii predicted one might see such two‐proton decay. Iron‐45, having 11 fewer neutrons than the most common isotope of iron, has only recently been produced in heavy‐ion accelerators. Now, research teams at the Laboratory for Heavy‐Ion Research (GSI) in Darmstadt, Germany, and at GANIL, a national heavy‐ion accelerator in Caen, France, have independently formed45Feand found evidence for two‐proton (2p) decay.

ISSN:0031-9228    

DOI:10.1063/1.1522200

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The thermodynamic behavior of microscopic systems can be quite different from that of macroscopic systems, for which fluctuations in thermodynamic quantities are usually negligible. As physicists strive to build ever smaller machines, it becomes important to understand, for example, the statistics of the work done on or by a machine as it moves from an initial to a final state. That work is not simply a function of the beginning and ending states. But—according to the usual telling of the story—the work is determined once one is given a path or process that connects the states.

ISSN:0031-9228    

DOI:10.1063/1.1522201

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Just a millimeter or so thick, the layers of cartilage in our knees can withstand compressive stresses of hundreds of kilopascals and tensile stresses ten times greater. Cartilage owes its remarkable resilience to the complex behavior and arrangement of its various molecular components. Unfortunately, like many carefully engineered devices, cartilage can go wrong. Twenty‐one million Americans endure osteoarthritis, a painful degradation of cartilage in knees and other joints.

ISSN:0031-9228    

DOI:10.1063/1.1522202

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Hands‐off management, bold political ambition, and fewer, bigger grants are the signatures of the Sixth Framework Programme (FP6), the blueprint for European science funding for the years 2003–06. In the new program, the traditional framework goal of fostering cross‐border connections among Europe's scientists is magnified. And, in a departure from the EC's infamous micromanagement style, scientists can look forward to less bureaucracy and more autonomy.

ISSN:0031-9228    

DOI:10.1063/1.1522203

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The demand for neutron sources in the US nearly doubled during the past decade while the availability of first‐rate instruments at neutron facilities declined more than 15&percent;. Add to that the 1999 closing of the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory, and the US science community is left at a significant disadvantage in neutron‐scattering capability compared to Western Europe and Japan. That is the conclusion of a new Office of Science and Technology Policy report that calls for improving, through better instrumentation and more efficient use, the overall quality of the handful of US neutron source facilities.

ISSN:0031-9228    

DOI:10.1063/1.1522204

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

In a comprehensive, 417‐page report designed to serve as a roadmap for the next decade of solar system exploration, a committee of planetary scientists is urging NASA to launch a reoriented Pluto–Kuiper Belt (PKB) mission and is advocating a return to costly, once‐a‐decade flagship missions in the $650 million to $1 billion range. The National Research Council (NRC) report, entitledNew Frontiers in the Solar System: An Integrated Exploration Strategy, was compiled at NASA's request and is modeled after the decadal reports in astronomy and astrophysics.

ISSN:0031-9228    

DOI:10.1063/1.1522205

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

As it gears up to build a jumbo solar telescope, the US National Solar Observatory is reclaiming independence from the National Optical Astronomy Observatory.

ISSN:0031-9228    

DOI:10.1063/1.1522206

出版商:AIP    

年代:1902

数据来源: AIP