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111.
After recalling the motivations for expecting supersymmetry to appear at energies 1 TeV, the reasons why the lightest supersymmetric particle is an ideal candidate for cold dark matter are reviewed. Recent calculations of the relic density including coannihilations and rapid annihilations through direct-channel Higgs boson poles are presented. The experimental constraints from LEP and elsewhere on supersymmetric dark matter are reviewed. The potential implications of a Higgs boson weighing about 115 GeV and the recent measurement of the anomalous magnetic moment of the muon are summarized. 相似文献
112.
John M. Logsdon 《Space Policy》2011,27(1):1-2
2010 saw both the unveiling of a new US National Space Policy and the announcement of a fundamentally different strategy for US human spaceflight that would move from the NASA-government-led Apollo-style approach to a greater reliance on the private sector and international cooperation. This viewpoint puts forward arguments on why change in the US approach to human spaceflight is needed, while acknowledging that achieving it in the face of vested interests and threats to jobs and livelihoods is extremely difficult. It suggests that greater US recognition of the need to ensure the sustainability of space activity (by addressing debris, radio-frequency interference and potential deliberate disruption of spacecraft), and an apparent willingness to countenance international norms to govern space activities, could be the new policy’s most lasting heritage. 相似文献
113.
John Elliott 《Acta Astronautica》2011,68(3-4):389-398
By investigating the generic attributes of a representative set of terrestrial languages at varying levels of abstraction, it is our endeavour to try and isolate elements of the signal universe, which are computationally tractable for its detection and structural decipherment. Ultimately, our aim is to contribute in some way to the understanding of what ‘languageness’ actually is. This paper describes algorithms and software developed to characterise and detect generic intelligent language-like features in an input signal, using natural language learning techniques: looking for characteristic statistical “language-signatures” in test corpora. As a first step towards such species-independent language-detection, we present a suite of programs to analyse digital representations of a range of data, and use the results to extrapolate whether or not there are language-like structures which distinguish this data from other sources, such as music, images, and white noise. 相似文献
114.
In 2010 the administration of President Barack Obama proposed a dramatically new approach to future US human spaceflight. That new strategy was immediately controversial. This article traces the origins of the new spaceflight strategy and the continuing political debate with respect to its acceptance. 相似文献
115.
116.
Sounding rocket experiment of bare electrodynamic tether system 总被引:1,自引:0,他引:1
Hironori A. Fujii Takeo Watanabe Hirohisa Kojima Koh-Ichiro Oyama Tairo Kusagaya Yoshiki Yamagiwa Hirotaka Ohtsu Mengu Cho Susumu Sasaki Koji Tanaka John Williams Binyamin Rubin Charles Les Johnson George Khazanov Juan R. Sanmartin Jean-Pierre Lebreton Erick J. van der Heide Michiel Kruijff Fabio De Pascal Pavel M. Trivailo 《Acta Astronautica》2009,64(2-3):313-324
An overview of a sounding rocket, S-520-25th, project on space tether technology experiment is presented. The project is prepared by an international research group consisting of Japanese, European, American, and Australian researchers. The sounding rocket will be assembled by the ISAS/JAXA and will be launched in the summer of 2009. The sounding rocket mission includes two engineering experiments and two scientific experiments. These experiments consist of the deployment of bare electrodynamic tape tether in space, a quick ignition test of hollow cathode system in space, the demonstration of bare electrodynamic tether system in space, and the test of the OML (orbital-motion-limit) current collection theory. 相似文献
117.
118.
John R. Percy 《Space Science Reviews》1980,27(3-4):313-322
Summary The most striking aspect of the Cep and 53 Per stars is their complexity. Whereas in Cepheid-type variables, a dominant mechanism excites a dominant mode (or two at most) of a dominant kind of pulsation, in Cep stars, a number of mechanisms and processes are at work. Still there is hope that the mystery will soon be unraveled by the careful application of a combination of observational and theoretical techniques. These same techniques will provide a better understanding of B stars in general: their interior and atmosphere, mass loss and coronal heating. 相似文献
119.
John Caldwell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(9):87-91
A decade of intense scientific study of Titan is reviewed. The atmosphere is not well understood at the time of this writing, but it is confidently expected that great progress will be made by the Voyager spacecraft now en route to the Saturn System. 相似文献
120.