38,528 research outputs found
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The role of structural embeddedness in an IT outsourcing network
The design of governance to safeguard against a vendor's opportunistic behaviour is one of the critical issues in information technology outsourcing (ITO) since this behaviour causes cost escalation and service debasement. The roles of structural embeddedness underlying network governance have been gaining its importance as complementary or substitutable governance in ITO. Our research attempts to reveal how structural embeddedness can affect the decision-makings of clients and vendors and their resulting outcomes in an ITO network and how these effects are moderated by various ITO network structures according to outsourced IT services. An agent-based simulation and game-theoretic approach are adopted to build a simulation model to describe ITO networks with various structures and ITO transactions between clients and vendors. Finally, the future research directions are discussed
Shape and spin distributions of asteroid populations from brightness variation estimates and large databases
Context. Many databases on asteroid brightnesses (e.g. ALCDEF, WISE) are
potential sources for extensive asteroid shape and spin modelling. Individual
lightcurve inversion models require several apparitions and hundreds of data
points per target. However, we can analyse the coarse shape and spin
distributions over populations of at least thousands of targets even if there
are only a few points and one apparition per asteroid. This is done by
examining the distribution of the brightness variations observed within the
chosen population.
Aims. Brightness variation has been proposed as a population-scale rather
than individual-target observable in two studies so far. We aim to examine this
approach rigorously to establish its theoretical validity, degree of
ill-posedness, and practical applicability.
Methods. We model the observed brightness variation of a target population by
considering its cumulative distribution function (CDF) caused by the joint
distribution function of two fundamental shape and spin indicators. These are
the shape elongation and the spin latitude of a simple ellipsoidal model. The
main advantage of the model is that we can derive analytical basis functions
that yield the observed CDF as a function of the shape and spin distribution.
The inverse problem can be treated linearly. Even though the inaccuracy of the
model is considerable, databases of thousands of targets should yield some
information on the distribution.
Results. We establish the theoretical soundness and the typical accuracy
limits of the approach both analytically and numerically. Using simulations, we
derive a practical estimate of the model distribution in the (shape,
spin)-plane. We show that databases such as Wide-field Infrared Survey Explorer
(WISE) yield coarse but robust estimates of this distribution, and as an
example compare various asteroid families with each other.Comment: 16 pages, 21 figures, manuscript accepted in Astronomy &
Astrophysics, to be published in section 10. Planets and planetary system
Logarithmic entropy--corrected holographic dark energy with non--minimal kinetic coupling
In this paper, we have considered a cosmological model with the non--minimal
kinetic coupling terms and investigated its cosmological implications with
respect to the logarithmic entropy-- corrected holographic dark energy
(LECHDE). The correspondence between LECHDE in flat FRW cosmology and the
phantom dark energy model with the aim to interpret the current universe
acceleration is also examined.Comment: 11 pages, 2 figures; Can. J. Phys. Vol. 90, 201
Diffusion of a Janus nanoparticle in an explicit solvent: A molecular dynamics simulation study
Molecular dynamics simulations are carried out to study the translational and
rotational diffusion of a single Janus particle immersed in a dense
Lennard-Jones fluid. We consider a spherical particle with two hemispheres of
different wettability. The analysis of the particle dynamics is based on the
time-dependent orientation tensor, particle displacement, as well as the
translational and angular velocity autocorrelation functions. It was found that
both translational and rotational diffusion coefficients increase with
decreasing surface energy at the nonwetting hemisphere, provided that the
wettability of the other hemisphere remains unchanged. We also observed that in
contrast to homogeneous particles, the nonwetting hemisphere of the Janus
particle tends to rotate in the direction of the displacement vector during the
rotational relaxation time.Comment: Web reference added for
animations:http://www.wright.edu/~nikolai.priezjev/janus/janus.htm
Complete gluon bremsstrahlung corrections to the process b -> s l+ l-
In a recent paper, we presented the calculation of the order (alpha_s)
virtual corrections to b->s l+ l- and of those bremsstrahlung terms which are
needed to cancel the infrared divergences. In the present paper we work out the
remaining order(alpha_s) bremsstrahlung corrections to b->s l+ l- which do not
suffer from infrared and collinear singularities. These new contributions turn
out to be small numerically. In addition, we also investigate the impact of the
definition of the charm quark mass on the numerical results.Comment: 20 pages including 11 postscript figure
Investigating the Effect of Stratospheric Radiation on Seed Germination and Growth
Three seed types: bean (Phaseolus vulgaris), corn (Zea mays) and radish (Raphanus sativus) were flown in a high altitude weather balloon into the mid-stratosphere to investigate the effects of high altitude radiation on germination success and seedling growth. After recovering and planting the seeds, the bean seeds showed lower germination success with exposure to high altitude radiation, and consequently stunted seedling growth. Cord and radish seeds experienced a statistically significant positive effect on germination success form radiation exposure compared to control seeds, but negative effect on seedling growth. Overall, the field experiments presented here support laboratory studies that show radiation exposure on vegetable seeds has a mixed effect on the germination success and negative effect on seedling growth on investigated seed types
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The Cell-Cycle Regulatory Protein p21CIP1/WAF1 Is Required for Cytolethal Distending Toxin (Cdt)-Induced Apoptosis.
The Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) induces lymphocytes to undergo cell-cycle arrest and apoptosis; toxicity is dependent upon the active Cdt subunit, CdtB. We now demonstrate that p21CIP1/WAF1 is critical to Cdt-induced apoptosis. Cdt induces increases in the levels of p21CIP1/WAF1 in lymphoid cell lines, Jurkat and MyLa, and in primary human lymphocytes. These increases were dependent upon CdtB's ability to function as a phosphatidylinositol (PI) 3,4,5-triphosphate (PIP3) phosphatase. It is noteworthy that Cdt-induced increases in the levels of p21CIP1/WAF1 were accompanied by a significant decline in the levels of phosphorylated p21CIP1/WAF1. The significance of Cdt-induced p21CIP1/WAF1 increase was assessed by preventing these changes with a two-pronged approach; pre-incubation with the novel p21CIP1/WAF1 inhibitor, UC2288, and development of a p21CIP1/WAF1-deficient cell line (Jurkatp21-) using clustered regularly interspaced short palindromic repeats (CRISPR)/cas9 gene editing. UC2288 blocked toxin-induced increases in p21CIP1/WAF1, and JurkatWT cells treated with this inhibitor exhibited reduced susceptibility to Cdt-induced apoptosis. Likewise, Jurkatp21- cells failed to undergo toxin-induced apoptosis. The linkage between Cdt, p21CIP1/WAF1, and apoptosis was further established by demonstrating that Cdt-induced increases in levels of the pro-apoptotic proteins Bid, Bax, and Bak were dependent upon p21CIP1/WAF1 as these changes were not observed in Jurkatp21- cells. Finally, we determined that the p21CIP1/WAF1 increases were dependent upon toxin-induced increases in the level and activity of the chaperone heat shock protein (HSP) 90. We propose that p21CIP1/WAF1 plays a key pro-apoptotic role in mediating Cdt-induced toxicity
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