124,584 research outputs found
Spin asymmetry in electron impact ionization of caesium
No full textBaum G, Granitza B, Grau L, et al. Spin asymmetry in electron impact ionization of caesium. J. Phy. B. 1993;26(2):331-336.We measured the total ionization asymmetry A in dependence on the incident electron energy E Here 'total' refers to integration over all emission angles and energy partitions of the outgoing electrons. From a threshold value of A = 0.1 25 the A(E) curve rises smoothly toward a broad maximum of A(max) = 0.31 at E(max) = 8.3 eV. The fall-off towards higher energies is quite similar to that of the other one-electron atoms. However, it shows a structure which can be explained by contributions from autoionizing P states. Bartschat has made a theoretical estimate of A(E) for various atoms. At low energies the agreement with our data is satisfactory, at higher energies the experimental A values are considerably smaller than the theoretical ones. In the threshold region measurements were performed with small electron energy width (0.1 eV). No structure in the A(E) curve was found. The slope at threshold was determined as dA/dE = (0.136+/-0.005) eV-1
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Simple and efficient method of spin-polarizing a metastable helium beam by diode laser optical pumping
No full textSpin polarized electron impact ionization of atoms
No full textBaum G, Freienstein P, Frost L, Granitza B, Raith W, Steidl H. Spin polarized electron impact ionization of atoms. In: Neill PA, Becker KH, Kelley MH, eds. Proceed. Int. Symp. on Correlation and Polarization in Electronic and Atomic Collisions, Hoboken 1989. Washington D.C. 20402: NIST Special Publication 789; 1990: 121-127
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Impact Ionization of Polarized Atoms by Polarized Electrons - Measurement of the Integral Polarization Asymmetry
No full textRaith W, Baum G, Granitza B, Leuer B, Steidl H. Impact Ionization of Polarized Atoms by Polarized Electrons - Measurement of the Integral Polarization Asymmetry. Institute of Physics Conference Series. 1992;(122):247-253.As a continuation of our asymmetry measurements for metastable helium (Baum et al. 1989) we are now concentrating on high-resolution studies near threshold. In another experiment we measured the ionization asymmetry A(I) as function of the energy E for cesium, employing optical pumping with two laser diodes for polarizing the Cs atoms (Baum et al. 1991). The obtained A(I) (E) curve of cesium is distinctly different from those for the other alkali atoms. It displays a maximum of 0.31 at E almost-equal-to 2 . E(I) which is significantly higher than the value at threshold of 0.16. Because of this increase of A(I) with energy in the near-threshold region the Cs asymmetry is similar to that of He(2(3)S). More theoretical work is desirable
Pragmatic Case Studies as a Source of Unity in Applied Psychology
No full textTo unify or not to unify applied psychology: that is the question. In this article we review pendulum swings in the historical efforts to answer this question—from a comprehensive, positivist, “top-down,” deductive yes between the 1930s and the early 60s, to a postmodern no since then. A rationale and proposal for a limited, “bottom-up,” inductive yes in applied psychology is then presented, employing a case-based paradigm that integrates both positivist and postmodern themes and components. This paradigm is labeled “pragmatic psychology” and, its specific use of case studies, the “Pragmatic Case Study Method” (“PCS Method”). We call for the creation of peer-reviewed journal-databases of pragmatic case studies as a foundational source of unifying applied knowledge in our discipline. As one example, the potential of the PCS Method for unifying different angles of theoretical regard is illustrated in an area of applied psychology, psychotherapy, via the case of Mrs. B. The article then turns to the broader historical and epistemological arguments for the unifying nature of the PCS Method in both applied and basic psychology.Peer reviewe
Dr. Edwin Wright Collection: Author Unknown
No full textNotes - The author relates several short stories about his neighbours including Alex McDonell, homesteading and life around Meanook and Athabasca (1 page
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
An optically pumped, highly polarized cesium beam for the study of spin-dependent electron scattering
No full textBaum G, Granitza B, Hesse S, et al. An optically pumped, highly polarized cesium beam for the study of spin-dependent electron scattering. Z.Phys. D. 1991;22(1):431-436.We have set up an atomic beam of cesium for the study of spin-dependent electron-cesium scattering. The beam is produced by an effusive oven with continuous recirculation of the condensed metal. The beam is optically pumped by circularly polarized light from two laser diodes tuned to the 6(2)S1/2(F = 3) --> 6(2)P3/2(F' = 4) and 6(2)S1/2(F = 4) --> 6(2)P3/2(F' = 5) transitions, respectively. Nearly all atoms are transferred into the F = 4, m(F) = +4 or m(F) = -4 Zeeman level of the ground state, depending on the sense of circular polarization of the pumping light. The population distribution in the optically pumped beam is analyzed in terms of the m(J) = - 1/2 and m(J) = + 1/2 components with a Stern-Gerlach magnet. We find the atomic polarization to be very close to unity at a density of 8 x 10(8) atoms/cm3 in the scattering center. The polarization decreases slightly with increasing density of the cesium beam due to radiation trapping. A spin flipper serves as a means of polarization reversal, introducing no systematic errors in the spin asymmetry measurements. Lock-in technique is used to stabilize the atomic beam polarization by detecting fluorescence light signals
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