571 research outputs found
Super-resolving multi-photon interferences with independent light sources
We propose to use multi-photon interferences from statistically independent
light sources in combination with linear optical detection techniques to
enhance the resolution in imaging. Experimental results with up to five
independent thermal light sources confirm this approach to improve the spatial
resolution. Since no involved quantum state preparation or detection is
required the experiment can be considered an extension of the Hanbury Brown and
Twiss experiment for spatial intensity correlations of order N>2
Numerical study of rainbows and glories in water-drop clouds
In this paper we study scattering phase functions in water-drop clouds for various distributions of droplet size and various conditions of glory, rainbow and corona formation, and discuss the hypothesis proposed by A. N. Nevzorov that a considerable amount of water in cold clouds can exist in a specific phase state with the refractive index ≈ 1.8 (so called A-water). Polarization and angular distributions are studied by the Monte Carlo method for radiation reflected by cloud layers with drops of water or hypothetical A-water taking into account multiple scattering. Computational results make it possible to develop procedures for analysis of microphysical structure of clouds and confirmation or disproof of the existence of A-water
Isotope shifts and hyperfine structure of the Fe I 372 nm resonance line
We report measurements of the isotope shifts of the Fe I resonance line at 372 nm between all four stable
isotopes Fe, Fe, Fe, and Fe, as well as the
complete hyperfine structure of that line for Fe, the only stable
isotope having a non-zero nuclear spin. The field and specific mass shift
coefficients of the transition have been derived from the data, as well as the
experimental value for the hyperfine structure magnetic dipole coupling
constant of the excited state of the transition in Fe: MHz. The measurements were done by means of Doppler-free
laser saturated-absorption spectroscopy in a Fe-Ar hollow cathode using both
natural and enriched iron samples. The measured isotope shifts and hyperfine
constants are reported with uncertainties at the percent level.Comment: 5 pages, 5 figure
Redetermination of cyclo-tetrakis(μ-5,10,15,20-tetra-4-pyridylporphyrinato)tetrazinc(II) dimethylformamide octasolvate trihydrate at 100 K
The structure of the title compound, [Zn4(C40H24N8)4]·8C3H7NO·3H2O, has been redetermined at 100 K. The redetermination is of significantly higher precision and gives further insight into the disorder of pyridyl groups and solvent molecules. The molecules of (5,10,15,20-tetra-4-pyridylporphyrinato)zinc(II) (ZnTPyP) form homomolecular cyclic tetramers by coordination of a peripheral pyridyl group to the central Zn atom of an adjacent symmetry-related molecule. The tetramer so formed exhibits molecular S
4 symmetry and is located about a crystallographic fourfold rotoinversion axis. Severely disordered dimethylformamide and water molecules are present in the crystal, the contributions of which were omitted from refinement. Intermolecular C—H⋯N hydrogen bonding is observed
Media Entrepreneurship:A Consensual Definition
Media Entrepreneurship has been an ambiguous, unclear and controversial concept and despite of growing academic efforts in the last decade, it is still a poorly defined subject. This paper is an effort to fill this gap by providing a comprehensive definition of media entrepreneurship. Firstly, a literature review conducted and entrepreneurship, media, opportunity and innovation as building blocks of media entrepreneurship explained. Then by using of a mixed of bibliographic method and a Delphi method with multi-stage analysis process, a consensual definition of media entrepreneurship proposed. This definition integrates some key features of the emerging media environment such as distinction of content and platform, value delivery, opportunity development, non-monetary benefit, etc. It is expected that the findings of this research clear the ground for further researches in the field of media entrepreneurshipEl emprendimiento mediático ha sido un concepto ambiguo, confuso y controversial y a pesar de los crecientes esfuerzos académicos de la última década, sigue siendo una materia de estudio no muy bien definida. Este artículo es un esfuerzo por llenar esta brecha al proveer una definición amplia sobre el emprendimiento mediático. En primer lugar, se lleva a cabo una revisión de la literatura y se ponen el em- prendimiento, los medios de comunicación, las oportunidades y la innovación como elementos básicos de la explicación del emprendimiento mediático. Luego, utilizando un método bibliográfico combinado y un método Delphi con un proceso de análisis de múltiples etapas, se propone una definición consen- suada del emprendimiento mediático. Esta definición integra algunas de las principales características del naciente entorno mediático tales como la distinción entre “contenido” y “plataforma”, “valor entre- gado”, “desarrollo de oportunidad”, “beneficio no monetario”, etc. Se espera que los hallazgos de esta investigación allanen el camino para futuros investigadores en el campo del emprendimiento mediátic
Bis[(E)-4-(hydroxyiminomethyl)pyridinium] oxalate
The formula unit of the title compound, 2C6H7N2O+·C2O4
2−, comprises two symmetry-equivalent 4-(hydroxyiminomethyl)pyridinium cations on general positions, linked through hydrogen bonding via an oxalate anion that resides on a crystallographic centre of symmetry. The crystal structure consists of infinite chains of cations and oxalate anions directed by O—H⋯O and multicentre N—H⋯O intermolecular hydrogen-bonding interactions
Di-μ-chlorido-bis{aquachlorido[2,2′-thiobis(pyridine N-oxide)-κO]copper(II)}
The crystal structure of the title compound, [Cu2Cl4(C10H8N2O2S)2(H2O)2], comprises neutral centrosymmetric μ-chloride-bridged dinuclear units. Each CuII ion is pentacoordinated by three chloride ligands, a pyridine N-oxide O atom and a water molecule. Intra- and intermolecular O—H⋯O hydrogen bonds occur between the coordinated water molecules and the uncoordinated and coordinated pyridine N-oxide groups of the 2,2′-thiobis(pyridine N-oxide) ligands, respectively
MeSi(CH2SnRO)3 (R = Ph, Me3SiCH2): Building blocks for triangular-shaped diorganotin oxide macrocycles
The syntheses of the novel silicon-bridged tris(tetraorganotin) compounds MeSi(CH2SnPh2R)3 (2, R=Ph; 5, R=Me3SiCH2) and their halogen-substituted derivatives MeSi(CH2SnPh(3−n)In)3 (3, n=1; 4, n=2) and MeSi(CH2SnI2R)3 (6, R=Me3SiCH2) are reported. The reaction of compound 4 with di-t-butyltin oxide (t-Bu2SnO)3 gives the oktokaideka-nuclear (18-nuclear) molecular diorganotin oxide [MeSi(CH2SnPhO)3]6 (7) while the reaction of 6 with sodium hydroxide, NaOH, provides the trikonta-nuclear (30-nuclear) molecular diorganotin oxide [MeSi(CH2SnRO)3]10 (8, R=Me3SiCH2). Both 7 and 8 show belt-like ladder-type macrocyclic structures and are by far the biggest molecular diorganotin oxides reported to date. The compounds have been characterized by elemental analyses, electrospray mass spectrometry (ESI-MS), NMR spectroscopy, 1H DOSY NMR spectroscopy (7), IR spectroscopy (7, 8), and single-crystal X-ray diffraction analysis (2, 7, 8)
Plans to eradicate invasive mammals on an island inhabited by humans and domestic animals (Corvo, Azores, Portugal)
Oppel, S., Beaven, B.M., Bolton, M., Bodey, T.W., Geraldes, P., Oliveira, N., Hervias, S., Henriques, A., Silva, C
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