20,864 research outputs found
The Propensity To Continue Service Internationalization - A Model Of Planned Behavior
The present study investigates the propensity to continue internationalization by experienced international service providers. Enhancing the cognitive-behavioral root of internationalization process theory (Johanson and Vahlne 1977; 1990), this paper builds upon Ajzen’s (1991) theory of planned behavior. Consistent with the latter theory, the propensity to continue service internationalization is modelled as behavioral intention that results from (1) an overall attitude towards internationalization, (2) structural and strategic behavioral norms, and (3) inhibiting factors that exert behavioral control upon propensity. Using partial least squares analysis, a propensity model is tested on a sample of 193 international service providers. The results suggest that our model explicates and enhances the cognitive/affective character of internationalization process theory.management and organization theory ;
Magnetic defects promote ferromagnetism in Zn1-xCoxO
Experimental studies of Zn1-xCoxO as thin films or nanocrystals have found
ferromagnetism and Curie temperatures above room temperature and that p- or
n-type doping of Zn1-xCoxO can change its magnetic state. Bulk Zn1-xCoxO with a
low defect density and x in the range used in experimental thin film studies
exhibits ferromagnetism only at very low temperatures. Therefore defects in
thin film samples or nanocrystals may play an important role in promoting
magnetic interactions between Co ions in Zn1-xCoxO. The electronic structures
of Co substituted for Zn in ZnO, Zn and O vacancies, substituted N and
interstitial Zn in ZnO were calculated using the B3LYP hybrid density
functional in a supercell. The B3LYP functional predicts a band gap of 3.34 eV
for bulk ZnO, close to the experimental value of 3.47 eV. Occupied minority
spin Co 3d levels are at the top of the valence band and unoccupied levels lie
above the conduction band minimum. Majority spin Co 3d levels hybridize
strongly with bulk ZnO states. The neutral O vacancy and interstitial Zn are
deep and shallow donors, respectively. The Zn vacancy is a deep acceptor and
the acceptor level for substituted N is at mid gap. The possibility that p- or
n-type dopants promote exchange coupling of Co ions was investigated by
computing total energies of magnetic states of ZnO supercells containing two Co
ions and an oxygen vacancy, substituted N or interstitial Zn in various charge
states. The neutral N defect and the singly-positively charged O vacancy are
the only defects which strongly promote ferromagnetic exchange coupling of Co
ions at intermediate range.Comment: 9 pages, 11 figure
The Frequency of Rapid Rotation Among K Giant Stars
We present the results of a search for unusually rapidly rotating giant stars
in a large sample of K giants (~1300 stars) that had been spectroscopically
monitored as potential targets for the Space Interferometry Mission's
Astrometric Grid. The stars in this catalog are much fainter and typically more
metal-poor than those of other catalogs of red giant star rotational
velocities, but the spectra generally only have signal-to-noise (S/N) of
~20-60, making the measurement of the widths of individual lines difficult. To
compensate for this, we have developed a cross-correlation method to derive
rotational velocities in moderate S/N echelle spectra to efficiently probe this
sample for rapid rotator candidates. We have discovered 28 new red giant rapid
rotators as well as one extreme rapid rotator with a vsini of 86.4 km/s. Rapid
rotators comprise 2.2% of our sample, which is consistent with other surveys of
brighter, more metal-rich K giant stars. Although we find that the temperature
distribution of rapid rotators is similar to that of the slow rotators, this
may not be the case with the distributions of surface gravity and metallicity.
The rapid rotators show a slight overabundance of low gravity stars and as a
group are significantly more metal-poor than the slow rotators, which may
indicate that the rotators are tidally-locked binaries.Comment: Accepted for publication in ApJ. 25 pages, 9 figures, 3 tables.
Tables 1 and 2 are provided in their full form as plain text ancillary file
Orbital Period Increase in ES Ceti
We report a long-term study of the eclipse times in the 10-minute helium
binary ES Ceti. The binary period increases rapidly, with P/P-dot = 6.2x10^6
yr. This is consistent with the assumption that gravitational radiation (GR)
drives the mass transfer, and appears to be the first dynamical evidence that
GR is indeed the driver of evolution in this class of very old cataclysmic
variables -- the AM Canum Venaticorum stars.Comment: PDF, 9 pages, 1 table, 1 figure; accepted, in press, ApJ; more info
at http://cbastro.org
WZ Sagittae as a DQ Herculis star
We argue that quiescent WZ Sge is a rapidly spinning magnetic rotator in
which most of the matter transfered from the secondary is ejected from the
system. Assuming that the observed 27.87 s oscillation period is due to the
spinning white dwarf we propose that the other observed principal period of
28.96 s is a beat due to reprocessing of the rotating white dwarf beam on
plasma blobs in Keplerian rotation at the outer disc rim. The weaker,
transient, 29.69 s period is identified as a beat with the Keplerian period of
the magnetosphere. WZ Sge evolves through a cycle of spin-up and spin-down
phases. During the spin-down phase it is a DQ Her star, during the spin-up
phase it should be a ER UMa star.Comment: 8 pages, 5 figures; accepted for publication in MNRA
Cold and Slow Molecular Beam
Employing a two-stage cryogenic buffer gas cell, we produce a cold,
hydrodynamically extracted beam of calcium monohydride molecules with a near
effusive velocity distribution. Beam dynamics, thermalization and slowing are
studied using laser spectroscopy. The key to this hybrid, effusive-like beam
source is a "slowing cell" placed immediately after a hydrodynamic, cryogenic
source [Patterson et al., J. Chem. Phys., 2007, 126, 154307]. The resulting CaH
beams are created in two regimes. One modestly boosted beam has a forward
velocity of vf = 65 m/s, a narrow velocity spread, and a flux of 10^9 molecules
per pulse. The other has the slowest forward velocity of vf = 40 m/s, a
longitudinal temperature of 3.6 K, and a flux of 5x10^8 molecules per pulse
The minimum period problem in cataclysmic variables
We investigate if consequential angular momentum losses (CAML) or an
intrinsic deformation of the donor star in CVs could increase the CV bounce
period from the canonical theoretical value ~65 min to the observed value
min, and if a variation of these effects in a CV population
could wash out the theoretically predicted accumulation of systems near the
minimum period (the period spike). We are able to construct suitably mixed CV
model populations that a statisticial test cannot rule out as the parent
population of the observed CV sample. However, the goodness of fit is never
convincing, and always slightly worse than for a simple, flat period
distribution. Generally, the goodness of fit is much improved if all CVs are
assumed to form at long orbital periods. The weighting suggested by King,
Schenker & Hameury (2002) does not constitute an improvment if a realistically
shaped input period distribution is used. Put your abstract here.Comment: 10 pages, Latex, 13 postscript figures, Accepted for publication in
MNRA
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