1,720,974 research outputs found
Molecular Regimes in Ultracold Fermi Gases
No full textThe use of Feshbach resonances for tuning the interparticle interaction in ultracold Fermi gases has led to remarkable developments, in particular to the creation and Bose-Einstein condensation of weakly bound diatomic molecules of fermionic atoms. These are the largest diatomic molecules obtained so far, with a size of the order of thousands of angstroms. They represent novel composite bosons, which exhibit features of Fermi statistics at short intermolecular distances. Being highly excited, these molecules are remarkably stable with respect to collisional relaxation, which is a consequence of the Pauli exclusion principle for identical fermionic atoms. The purpose of this review is to introduce theoretical approaches and describe the physics of molecular regimes in two-component Fermi gases and Fermi-Fermi mixtures, focusing attention on quantum statistical effects
Distribution of energy in bimolecular chemiluminescent reactions involving hydrogen atoms. Progress report, May 1, 1977--April 30, 1978. [Summaries of research activities at the University of Iowa]
No full textAnalysis of spectroscopic observations of the production of photons throughout the visible region from the collision of approximately 5 eV H atoms with a Li/Li/sub 2/ crossed beam is described. The present state and future plans for the photon-detection experiments are discussed. Complementary theoretical and nobeam spectroscopic work related to the Li/sub 2/H system is also noted. A list of publications is included
Distribution of energy in bimolecular chemiluminescent reactions involving hydrogen atoms. Final report, May 1, 1978-April 30, 1979
No full textAnalysis of spectroscopic observations of the production of visible and ultraviolet photons from the collision of approx. 5-eV H atoms with a Li/Li/sub 2/ crossed beam and with 0/sub 2/ and H/sub 2/O crossed beams is described. Complementary theoretical and nonbeam spectroscopic work related to the Li/sub 2/H system is also noted. 5 figures, 1 table
Distribution of energy in bimolecular chemiluminescent reactions involving hydrogen atoms. Progress report, May 1, 1974--April 30, 1975
No full textThe final stages of development of a crossed molecular beam apparatus for the study of bimolecular chemiluminescent reactions involving hydrogen atoms are described. A stable, high intensity, high energy source of H atoms is operating and its intensity was estimated by two different methods to be ~10/sup 15/ H atoms/cm/sup 2/-sec at 1 meter. The determination of the velocity distribution of H atoms from this source is the only remaining major project planned prior to observation of chemiluminescence. Other aspects of the apparatus, e.g., the exemplary performance of the photon counting system, are also discussed. Related theoretical and nonbeam spectroscopic work to further understanding of the first chemiluminescing molecule sought, LiH, and of the first total reactive system, Li/sub 2/H, is noted. (auth
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
High-resolution spectroscopy of long-range molecular states of 85Rb2
Full text linkWe present analysis of low- long-range molecular Rydberg states in Rb, based on high-resolution spectra. The weakly bound states are accessed by bound-bound transitions from high- levels of the state, which are prepared by photoassociation of laser-cooled atoms. Single-photon transitions to target states near the asymptote are excited by a frequency-doubled pulse-amplified CW laser with a narrow linewidth, under 200 MHz. The long-range portion of the bonding potential is dominated by the elastic scattering interaction of the Rydberg electron of a perturbed atom and a nearby ground-state atom, in much the same manner as trilobite states. We use time of flight to selectively measure molecular ions, which are formed via autoionization. This technique gives a two orders-of-magnitude improvement in linewidth over our previous work, reported in Ref. [1]. We also present calculations of a proposed scheme for STIRAP transfer from the current level of the state to the level. The long-range states accessible to us are defined in large part by the Franck-Condon factors, which are dominated by the outer lobe of the wavefunction. Thus, choosing a sets , and determines the Franck-Condon window. The proposed level has a classical outer turning point at , and will provide access to higher- states with longer-range wells. This work is supported by the NSF and AFOSR.\
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[1] M. A. Bellos textit{et al.}, Phys. Rev. Lett. textbf{111}, 053001 (2013)Made available in DSpace on 2016-01-05T20:07:23Z (GMT). No. of bitstreams: 3
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Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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