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Dmitry V Strelnikov, Bastian Kern, Manfred M Kappes
We have observed that C60+ ions isolated in cryogenic matrixes show distinct near-IR photoluminescence upon excitation in the near-IR range. By contrast UV photoexcitation does not lead to measurable luminescence. The near-IR C60+ photoluminescence is a one-photon process. The emission is mainly concentrated in one band and corresponds to 2A1u<- 2E1g relaxation. We present experimental data for the Stokes shift, power and temperature dependencies as well as the quantum efficiency of the photoluminescence...
September 8, 2017: Journal of Physical Chemistry. A
Steven N Shore
No abstract text is available yet for this article.
August 30, 2017: Nature
Peter J Forshaw
This essay examines the elaborate title pages of some of alchemist, astrologer, and bibliophile John Dee's publications with a focus on the two best known works that feature his famous Hieroglyphic Monad, the Propaedeumata Aphoristica (1558) and Monas Hieroglyphica (1564). The aim is to cast light on its context, identify sources for some textual influences in the works, unpack the visual symbolism in the two "monadic" title pages in relation to the two complementary sciences of "superior" and "inferior" astronomy, speculate on some of the more enigmatic details, and conclude with a brief discussion of a possible astrological significance to the dates of composition of the Monas Hieroglyphica...
August 21, 2017: Ambix
Gail H Schaefer
No abstract text is available yet for this article.
August 16, 2017: Nature
Kevin Heng
No abstract text is available yet for this article.
August 2, 2017: Nature
John P Wikswo
John Wikswo talks to Francesca Lake, Managing Editor: John is the founding Director of the Vanderbilt Institute for Integrative Biosystems Research and Education (VIIBRE). He is also the Gordon A Cain University Professor; a B learned Professor of Living State Physics; and a Professor of Biomedical Engineering, Molecular Physiology and Biophysics, and Physics. John earned his PhD in physics at Stanford University (CA, USA). After serving as a Research Fellow in Cardiology at Stanford, he joined the Department of Physics and Astronomy at Vanderbilt University (TN, USA), where he went on to make the first measurement of the magnetic field of an isolated nerve...
June 2017: Future Science OA
Michael Pircher, Robert J Zawadzki
In vivo imaging of the human retina with a resolution that allows visualization of cellular structures has proven to be essential to broaden our knowledge about the physiology of this precious and very complex neural tissue that enables the first steps in vision. Many pathologic changes originate from functional and structural alterations on a cellular scale, long before any degradation in vision can be noted. Therefore, it is important to investigate these tissues with a sufficient level of detail in order to better understand associated disease development or the effects of therapeutic intervention...
May 1, 2017: Biomedical Optics Express
Daniel Špelda
In the eighteenth century, the historiography of astronomy was part of a wider discussion concerning the history of the human spirit. The concept of the human spirit was very popular among Enlightenment authors because it gave the history of human knowledge continuity, unity and meaning. Using this concept, scientists and historians of science such as Montucla, Lalande, Bailly and Laplace could present the history of astronomy in terms of a progress towards contemporary science that was slow and could be interrupted at times, but was still constant, regular, and necessary...
June 2017: Studies in History and Philosophy of Science
Bo Da, Jiangwei Liu, Mahito Yamamoto, Yoshihiro Ueda, Kazuyuki Watanabe, Nguyen Thanh Cuong, Songlin Li, Kazuhito Tsukagoshi, Hideki Yoshikawa, Hideo Iwai, Shigeo Tanuma, Hongxuan Guo, Zhaoshun Gao, Xia Sun, Zejun Ding
Characterization techniques available for bulk or thin-film solid-state materials have been extended to substrate-supported nanomaterials, but generally non-quantitatively. This is because the nanomaterial signals are inevitably buried in the signals from the underlying substrate in common reflection-configuration techniques. Here, we propose a virtual substrate method, inspired by the four-point probe technique for resistance measurement as well as the chop-nod method in infrared astronomy, to characterize nanomaterials without the influence of underlying substrate signals from four interrelated measurements...
May 26, 2017: Nature Communications
Rychard Bouwens
No abstract text is available yet for this article.
May 24, 2017: Nature
Jay Pasachoff
No abstract text is available yet for this article.
May 24, 2017: Nature
Kathleen L Prudic, Kent P McFarland, Jeffrey C Oliver, Rebecca A Hutchinson, Elizabeth C Long, Jeremy T Kerr, Maxim Larrivée
Data collection, storage, analysis, visualization, and dissemination are changing rapidly due to advances in new technologies driven by computer science and universal access to the internet. These technologies and web connections place human observers front and center in citizen science-driven research and are critical in generating new discoveries and innovation in such fields as astronomy, biodiversity, and meteorology. Research projects utilizing a citizen science approach address scientific problems at regional, continental, and even global scales otherwise impossible for a single lab or even a small collection of academic researchers...
May 18, 2017: Insects
Nees Jan van Eck, Ludo Waltman
Clustering scientific publications in an important problem in bibliometric research. We demonstrate how two software tools, CitNetExplorer and VOSviewer, can be used to cluster publications and to analyze the resulting clustering solutions. CitNetExplorer is used to cluster a large set of publications in the field of astronomy and astrophysics. The publications are clustered based on direct citation relations. CitNetExplorer and VOSviewer are used together to analyze the resulting clustering solutions. Both tools use visualizations to support the analysis of the clustering solutions, with CitNetExplorer focusing on the analysis at the level of individual publications and VOSviewer focusing on the analysis at an aggregate level...
2017: Scientometrics
Safvet Halilović
Islam and its followers had created a civilization that played very important role on the world stage for more than a thousand years. One of the most important specific qualities of the Islamic civilization is that it is a well-balanced civilization that brought together science and faith, struck a balance between spirit and matter and did not separate this world from the Hereafter. This is what distinguishes the Islamic civilization from other civilizations which attach primary importance to the material aspect of life, physical needs and human instincts, and attach greater attention to this world by striving to instantly satisfy desires of the flesh, without finding a proper place for God and the Hereafter in their philosophies and education systems...
April 2017: Psychiatria Danubina
Denis Mourard, Philippe Bério, Karine Perraut, Jean-Michel Clausse, Orlagh Creevey, Marc-Antoine Martinod, Anthony Meilland, Florentin Millour, Nicolas Nardetto
High angular resolution studies of stars in the optical domain have highly progressed in recent years. After the results obtained with the visible instrument Visible spEctroGraph and polArimeter (VEGA) on the Center for High Angular Resolution Astronomy (CHARA) array and the recent developments on adaptive optics and fibered interferometry, we have started the design and study of a new six-telescope visible combiner with single-mode fibers. It is designed as a low spectral resolution instrument for the measurement of the angular diameter of stars to make a major step forward in terms of magnitude and precision with respect to the present situation...
May 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Michelle J Creech-Eakman, P Scott Carney, David F Buscher, Michael Shao
Aperture synthesis methods allow the reconstruction of images with the angular resolutions exceeding that of extremely large monolithic apertures by using arrays of smaller apertures together in combination. In this issue we present several papers with techniques relevant to amplitude interferometry, laser radar, and intensity interferometry applications.
May 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Jonathan Ko, Christopher C Davis
Adaptive optics has been successfully used for decades in the field of astronomy to correct for atmospheric turbulence. A well-developed example involves sensing the slightly distorted wavefronts with a Shack-Hartmann sensor and then correcting them with a phase conjugate device. While the Shack-Hartmann sensor has proven effective for astronomical purposes, it has been less successful for use in deep turbulence conditions often found in ground-to-ground-based optical systems. We have studied an alternative way to sense and correct distorted wavefronts using a plenoptic sensor...
May 1, 2017: Applied Optics
D Ortiz, Francisco J Casas, R Ruiz-Lombera, J Mirapeix
In this paper, a microwave interferometer prototype with a near-infra-red optical correlator is proposed as a solution to get a large-format interferometer with hundreds of receivers for radio astronomy applications. A 10 Gbits/s Lithium Niobate modulator has been tested as part of an electro-optic correlator up-conversion stage that will be integrated in the interferometer prototype. Its internal circuitry consists of a single-drive modulator biased by a SubMiniature version A (SMA) connector allowing to up-convert microwave signals with bandwidths up to 12...
April 2017: Review of Scientific Instruments
Rashid Mehmood, Saeed El-Ashram, Rongfang Bie, Hussain Dawood, Anton Kos
Clustering is an unsupervised approach to classify elements based on their similarity, and it is used to find the intrinsic patterns of data. There are enormous applications of clustering in bioinformatics, pattern recognition, and astronomy. This paper presents a clustering approach based on the idea that density wise single or multiple connected regions make a cluster, in which density maxima point represents the center of the corresponding density region. More precisely, our approach firstly finds the local density regions and subsequently merges the density connected regions to form the meaningful clusters...
April 19, 2017: Scientific Reports
S Mohammad Mozaffari
Argument In the Almagest, Ptolemy finds that the apogee of Mercury moves progressively at a speed equal to his value for the rate of precession, namely one degree per century, in the tropical reference system of the ecliptic coordinates. He generalizes this to the other planets, so that the motions of the apogees of all five planets are assumed to be equal, while the solar apsidal line is taken to be fixed. In medieval Islamic astronomy, one change in this general proposition took place because of the discovery of the motion of the solar apogee in the ninth century, which gave rise to lengthy discussions on the speed of its motion...
March 2017: Science in Context
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