165 research outputs found
Observations of Neutron-Capture Elements in the Early Galaxy
Neutron-capture elements in low metallicity Galactic halo stars vary widely
both in overall contents and detailed abundance patterns. This review discusses
recent observational results on the n-capture elements, discussing the
implications for early Galactic nucleosynthesis of: (a) the star-to-star
``bulk'' variations in the n-capture/Fe abundance ratios; (b) the distinct
signature of rapid n-capture synthesis events in many (most?) of the lowest
metallicity stars; (c) the existence of metal-poor stars heavily enriched in
the products of slow n-capture synthesis reactions; and (d) the now-routine
detection of radioactive thorium (and even uranium in one and possibly two
cases) in the spectra of metal-poor stars.Comment: 8 pages, 3 figures; To appear in the Proceedings of the 7th
International Conference on Nuclei in the Cosmo
Doppler-free frequency modulation spectroscopy of atomic erbium in a hollow cathode discharge cell
The erbium atomic system is a promising candidate for an atomic Bose-Einstein
condensate of atoms with a non-vanishing orbital angular momentum ()
of the electronic ground state. In this paper we report on the frequency
stabilization of a blue external cavity diode laser system on the 400.91
laser cooling transition of atomic erbium. Doppler-free saturation spectroscopy
is applied within a hollow cathode discharge tube to the corresponding
electronic transition of several of the erbium isotopes. Using the technique of
frequency modulation spectroscopy, a zero-crossing error signal is produced to
lock the diode laser frequency on the atomic erbium resonance. The latter is
taken as a reference laser to which a second main laser system, used for laser
cooling of atomic erbium, is frequency stabilized
Abundances of the elements in the solar system
A review of the abundances and condensation temperatures of the elements and
their nuclides in the solar nebula and in chondritic meteorites. Abundances of
the elements in some neighboring stars are also discussed.Comment: 42 pages, 11 tables, 8 figures, chapter, In Landolt- B\"ornstein, New
Series, Vol. VI/4B, Chap. 4.4, J.E. Tr\"umper (ed.), Berlin, Heidelberg, New
York: Springer-Verlag, p. 560-63
Solar System Abundances of the Elements
Representative abundances of the chemical elements for use as a solar
abundance standard in astronomical and planetary studies are summarized.
Updated abundance tables for solar system abundances based on meteorites and
photospheric measurements are presented.Comment: 46 pages; 5 figures; 8 tables; In: Principles and Perspectives in
Cosmochemistry.Lecture Notes of the Kodai School on 'Synthesis of Elements in
Stars' held at Kodaikanal Observatory, India, April 29 - May 13, 2008 (Aruna
Goswami and B. Eswar Reddy eds.) Astrophysics and Space Science Proceedings,
Springer-Verlag Berlin Heidelberg, 2010, p. 379-417 (ISBN 978-3-642-10351-3),
201
History of clinical transplantation
How transplantation came to be a clinical discipline can be pieced together by perusing two volumes of reminiscences collected by Paul I. Terasaki in 1991-1992 from many of the persons who were directly involved. One volume was devoted to the discovery of the major histocompatibility complex (MHC), with particular reference to the human leukocyte antigens (HLAs) that are widely used today for tissue matching.1 The other focused on milestones in the development of clinical transplantation.2 All the contributions described in both volumes can be traced back in one way or other to the demonstration in the mid-1940s by Peter Brian Medawar that the rejection of allografts is an immunological phenomenon.3,4 © 2008 Springer New York
Human Resource Flexibility as a Mediating Variable Between High Performance Work Systems and Performance
Much of the human resource management literature has demonstrated the impact of high performance
work systems (HPWS) on organizational performance. A new generation of studies is
emerging in this literature that recommends the inclusion of mediating variables between HPWS
and organizational performance. The increasing rate of dynamism in competitive environments
suggests that measures of employee adaptability should be included as a mechanism that may
explain the relevance of HPWS to firm competitiveness. On a sample of 226 Spanish firms, the
study’s results confirm that HPWS influences performance through its impact on the firm’s
human resource (HR) flexibility
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