86,648 research outputs found
Spectroscopy and energy transfer parameters of Tm3+- and Ho3+-doped Ba2NaNb5O15 single crystals
No full textThe absorption and emission spectra of Tm3+- and Ho3+-doped Ba2NaNb5O15 crystals have been measured in the 1.5-2 mu m region. The lifetimes of the lowest excited states have been measured at 10 and at 298 K. The cross sections of the (Tm) F-3(4) H-3(6) and (Ho) I-5(7) I-5(8) transitions have been estimated and used to determine the (Tm) F-3(4) -> (Ho) I-5(7) energy transfer parameter. These results are discussed in order to evaluate the potentialities of this material as active medium in solid-state lasers operating at 2 Pm. (c) 2006 Elsevier B.V. All rights reserved
Optical spectroscopy of SrWO4 : Nd3+ single crystals
No full textThe optical properties of SrWO4 crystals doped with Nd3+ have been investigated at temperatures ranging from 10 to 300 K. The scheme of the energy levels up to 20 000 cm(-1) has been deduced from low temperature measurements and reproduced by theoretical calculations based on a parametric Hamiltonian including Coulombic, spin-orbit and crystal field terms. The spontaneous transition probabilities, the branching ratios and the radiative lifetime have been calculated in the framework of the Judd-Ofelt theory and compared with the experimental results for the F-4(3/2) emitting level. The optical bands are broadened because of crystal field inhomogeneities caused by charge compensation processes accompanying the substitution of Nd3+ for Sr2+. This fact and the high emission cross section values obtained for the emission from the F-4(3/2) multiplet indicate Nd:SrWO4 as a possible. active medium for tunable laser operation
FIRST ASSESSMENTS ON HERITAGE SCIENCE ORIENTED IMAGE-BASED MODELING USING LOW-COST MODIFIED AND MOBILE CAMERAS
No full textThree-dimensional modeling of cultural heritage, especially concerning large scale studies, as for example, archaeometry, diagnostics and conservation intervention applications, which usually require high-resolution and multi-spectral analyses, necessitates the use of complicate and often expensive equipment. Recent developments regarding low-cost commercially available spectrally modified digital reflex cameras, smartphones with good quality image sensors, mobile thermal cameras in combination with automated or semi-automated photogrammetric software implementing Structure from Motion (SfM) and Multiview Stereo (MVS) algorithms constitute some cheaper and simpler alternatives. Although, the results of the integration of these types of sensors and techniques are often not evaluated as metric products. The presented research combines the above-mentioned instrumentation and software to implement and evaluate low-cost 3D modeling solutions on heritage science-oriented case studies, but also to perform some first assessments on the resulting models' metric properties, quality of texture and usefulness for further scientific investigations
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Optical spectroscopy and crystal-field analysis of YAl3(BO3)4 single crystals doped with dysprosium
No full textYAl3(BO3)(4) crystals doped with Dy3+ were grown from a potassium trimolybdate flux. Their absorption and visible emission spectra and decay curves were measured at temperatures ranging from 10 to 298 K. The complete energy level scheme has been deduced from the low temperature measurements and reproduced by theoretical calculations based on a parametric Hamiltonian including coulombic, spin-orbit and crystal-field terms. The Judd-Ofelt parametrization scheme has been applied to the analysis of the room temperature absorption spectra. The calculated radiative lifetime of the F-4(9/2) state is 344 mus; this value is reasonably consistent with the experimental data
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
John F. Kennedy telegram to Roosevelt
No full textJersey Homesteads (later the Borough of Roosevelt) was established in the 1930s as an agro-industrial cooperative community. It was established specifically for urban Jewish garment workers, many of whom had emigrated from Europe. President John F. Kennedy sent a telegram to the citizens of Roosevelt, New Jersey, apologizing for not being able to attend the memorial dedication in honor of former President Franklin Delano Roosevelt. (Jersey Homesteads became Roosevelt in 1945 in honor of the president.) President Kennedy expressed his gratitude to the people of Roosevelt for constructing the memorial, and commented that it will serve as a constant reminder of Roosevelt's good works
Logarithmic variance profiles and the corresponding f-1 spectra of temperature fluctuations in turbulent Rayleigh-Bénard convection
No full textWe report experimental results for the temperature variance 2(z) and the corresponding frequency spectra P(f) in turbulent Rayleigh-Bénard convection (RBC) in a cylindrical sample of aspect ratioT= D/L = 1:00 (D = 1:12 m is the diameter and L = 1:12 m the height). The measurements were conducted in the Rayleigh-number range 1011 < Ra < 1:35 1014 and Pr ' 0:8. For Ra = 1:35x1014, 2(z) could be described well by a logarithmic dependence on the vertical position z in a range of z 1 < z < z 2 with z 1 ' 70 and z 2 = 0:1L. Here L=(2Nu) is the thickness of a thin thermal sublayer adjacent to the horizontal plate where the heat flux (denoted by the Nusselt number Nu) is carried mostly by thermal diffusion. In the log layer, we found that the temperature spectra had a significant frequency range over which P(f) f with close to 1. As Ra decreased, increased so that the log layer became thinner. At Ra = 2:05 1011, z 2 < z 1 and therefore there was no range for a log layer. Correspondingly, the temperature spectrum near the horizontal plate did not have the f1 scaling form either
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