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The origin and nature of ultrahigh-energy cosmic rays (UHECRs, E > 1018 eV) is one of the most intriguing unsolved problems of modern astrophysics. This review is dedicated to the current status of research in this field. We describe the largest ongoing experiments carried out at the Pierre Auger Observatory and Telescope Array, at the first orbital detector of UHECRs, that is, TUS, and for the KLPVE and JEM-EUSO orbital telescopes, which are currently being developed. We discuss the latest results on the energy spectrum and mass composition of UHECRs and the relationship between UHECRs on the one hand and ultrahigh-energy neutrinos and photons on the other. Finally, we review the latest results on the anisotropy of the arrival directions of UHECRs, which is a crucially important area of research in the search for astrophysical sources of cosmic rays in the highest energy range. 相似文献
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For the benefit of the readers of this journal, the editors requested that we prepare a brief review of the history of the development of the theory, the experimental attempts to detect them, and the recent direct observations of gravitational waves (GWs). The theoretical ideas and disputes beginning with Einstein in 1916 regarding the existence and nature of gravitational waves and the extent to which one can rely on the electromagnetic analogy, especially the controversies regarding the quadrupole formula and whether gravitational waves carry energy, are discussed. The theoretical conclusions eventually received strong observational support from the binary pulsar. This provided compelling, although indirect, evidence for gravitational waves carrying away energy—as predicted by the quadrupole formula. On the direct detection experimental side, Joseph Weber started more than fifty years ago. In 1966, his bar for GW detection reached a strain sensitivity of a few times . His announcement of coincident signals (now considered spurious), stimulated many experimental efforts from room temperature resonant masses to cryogenic detectors and laser-interferometers. Now there are km-sized interferometric detectors (LIGO Hanford, LIGO Livingston, Virgo and KAGRA). Advanced LIGO first reached a strain sensitivity of the order of . During their first 130 days of observation (O1 run), with the aid of templates generated by numerical relativity, they did make the first detections: two 5-σ GW events and one likely event. Besides earth-based GW detectors, the drag-free sensitivity of the LISA Pathfinder has already reached to the LISA goal level, paving the road for space GW detectors. Over the whole GW spectrum (from aHz to THz) there are efforts for detection, notably the very-low-frequency band (pulsar timing array [PTA], 300 pHz – 100 nHz) and the extremely-low (Hubble)-frequency (cosmic microwave background [CMB] experiment, 1 aHz – 10 fHz). 相似文献
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M. E. Himbert 《The European physical journal. Special topics》2009,172(1):25-35
The aim of this paper is to situate the subject of measurement and metrology in its historical and philosophical context.
Everyone agrees that the numeration of objects and the quantification of the characteristics of some simple systems are very
ancient practices encountered in any specific civilisation. Indeed the link between measurement and numeration comes from
the beginnings. This is recalled here, as are the links between units and money, between references and authority. Then, the
paper identifies and exhibits the different epistemological gaps occurred – or occurring – in the history of measurement in
the western countries: geometry versus arithmetics, model versus experiment, prediction versus uncertainty, determinism versus
quantum physics. Those gaps are described in relationship to the evolution of the internationally agreed system of units. 相似文献
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The evolution of cathode lens-based photo emission electron microscopy (PEEM) from the simple beginnings in the early 1930s to its sophisticated present state is discussed. In addition to conventional ultraviolet light-excited PEEM (UV-PEEM), laser excited PEEM and the various modes of synchrotron X-ray-excited PEEM (XPEEM) particular emphasis is placed on the complementary combination of these methods with low energy electron microscopy (LEEM). 相似文献
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Human beings have had an inherent urge to leave their mark in the form of works of art since prehistoric times. This has driven the quest for new and better pigments with which to make paints. This paper describes the origins and composition of earliest earth pigments used by primitive man to decorate the walls of caves through to the synthetic pigments developed in more recent times. Despite modern technology, the artist's palette remains a mixture of the pigments used by cave artists, natural pigments used in the middle ages, and modern organic compounds. 相似文献
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《Comptes Rendus Physique》2015,16(5):461-470
In this article, we report on the work done with the LNE–SYRTE atomic clock ensemble during the last 10 years. We cover the progress made in atomic fountains and in their application to timekeeping. We also cover the development of optical lattice clocks based on strontium and on mercury. We report on tests of fundamental physical laws made with these highly accurate atomic clocks. We also report on work relevant to a future possible redefinition of the SI second. 相似文献
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Atomic clocks based on coherent population trapping: a review 总被引:3,自引:0,他引:3
J. Vanier 《Applied physics. B, Lasers and optics》2005,81(4):421-442
The paper gives an overview of the use of the coherent population trapping phenomenon (CPT) in alkali-metal atoms in the implementation of atomic frequency standards. Several avenues are examined. These include: the approach using a combination of the CPT phenomenon and the Ramsey separated interaction field technique on an atomic beam; the passive approach in a cell in which the microwave hyperfine resonance excited by the CPT phenomenon is detected directly on the transmitted radiation; the maser approach in which the same resonance is observed by means of stimulated emission in a microwave cavity-cell arrangement; and, finally, the proposed approach using pulses in a time sequence that implements the combined CPT–Ramsey separated interaction field technique in time rather than in space. A review of field and laboratory implementations using these approaches is made. 相似文献
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Narahashi T 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(5):147-154
Tetrodotoxin (TTX), contained in puffer, has become an extremely popular chemical tool in the physiological and pharmacological laboratories since our discovery of its channel blocking action in the early 1960s. This brief review describes the history of discovery of TTX action on sodium channels, and represents a story primarily of my own work. TTX inhibits voltage-gated sodium channels in a highly potent and selective manner without effects on any other receptor and ion channel systems. TTX blocks the sodium channel only from outside of the nerve membrane, and is due to binding to the selectivity filter resulting in prevention of sodium ion flow. It does not impairs the channel gating mechanism. More recently, the TTX-resistant sodium channels have been discovered in the nervous system and received much attention because of their role in pain sensation. TTX is now known to be produced not by puffer but by bacteria, and reaches various species of animals via food chain.(Communicated by Masanori OTSUKA, M.J.A.). 相似文献
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人们对泡沫习以为常,却很难理解它的奇特性质,比如几乎完全由空气组成的泡沫,既能像固体一样发生弹性形变,又能像流体一样发生流动,这正是泡沫物理学的研究内容之一.泡沫物理是一门古老的学科,早在19世纪中下叶,气泡和泡沫结构静力学的描述已经完美,之后没有大的发展,直到1990年前后,随着流体力学、微观显像技术和计算技术等学科的发展,以及受材料科学和工业生产的需求,泡沫物理研究再次活跃起来.文章第一作者曾跟随英国皇家学会院士Denis Weaire从事泡沫物理研究多年,在他的演讲和个人收藏中,文章作者积累了一些材料,在此基础上,又仔细查阅了相关文献,整理成此文,它基本概括了泡沫结构静力学发展历程中的重要事件. 相似文献
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泡沫物理学史拾萃 总被引:4,自引:0,他引:4
人们对泡沫习以为常,却很难理解它的奇特性质,比如几乎完全由空气组成的泡沫,既能像固体一样发生弹性形变,又能像流体一样发生流动,这正是泡沫物理学的研究内容之一.泡沫物理是一门古老的学科,早在19世纪中下叶,气泡和泡沫结构静力学的描述已经完美,之后没有大的发展,直到1990年前后,随着流体力学、微观显像技术和计算技术等学科的发展,以及受材料科学和工业生产的需求,泡沫物理研究再次活跃起来.文章第一作者曾跟随英国皇家学会院士Denis Weaire从事泡沫物理研究多年,在他的演讲和个人收藏中,文章作者积累了一些材料,在此基础上,又仔细查阅了相关文献,整理成此文,它基本概括了泡沫结构静力学发展历程中的重要事件. 相似文献
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希格斯玻色子于2012年的发现是粒子物理发展史上的一座里程碑。它为标准模型补上了最后一块拼图,希格斯机制的提出者们也因此获得了2013年的诺贝尔物理学奖。在希格斯玻色子发现十周年之际,文章将带领读者简短回顾希格斯玻色子从提出到发现的近半个世纪的历史。 相似文献