2,510 research outputs found
Perceived Organisational Support and Profitability
This paper investigates the impact of perceived organizational support (POS) on performance.We predict that POS will be reciprocated by positive discretionary employee behavior, which in turn has a positive impact on performance.Empirical research on a sample of Dutch construction companies indeed corroborates a positive relationship between POS and performance. Moreover, the POS-performance link is found to be stronger for good performing firms than for bad performing firms, which supports that reciprocity drives the relationship between POS and performance.
Indexed induction and coinduction, fibrationally.
This paper extends the fibrational approach to induction and coinduction pioneered by Hermida and Jacobs, and developed by the current authors, in two key directions. First, we present a sound coinduction rule for any data type arising as the final coalgebra of a functor, thus relaxing Hermida and Jacobsâ restriction to polynomial data types. For this we introduce the notion of a quotient category with equality (QCE), which both abstracts the standard notion of a fibration of relations constructed from a given fibration, and plays a role in the theory of coinduction dual to that of a comprehension category with unit (CCU) in the theory of induction. Second, we show that indexed inductive and coinductive types also admit sound induction and coinduction rules. Indexed data types often arise as initial algebras and final coalgebras of functors on slice categories, so our key technical results give sufficent conditions under which we can construct, from a CCU (QCE) U : E -> B, a fibration with base B/I that models indexing by I and is also a CCU (QCE)
Welfarism vs. extra-welfarism
'Extra-welfarism' has received some attention in health economics, yet there is little consensus on what distinguishes it from more conventional 'welfarist economics'. In this paper, we seek to identify the characteristics of each in order to make a systematic comparison of the ways in which they evaluate alternative social states. The focus, though this is not intended to be exclusive, is on health. Specifically, we highlight four areas in which the two schools differ: (i) the outcomes considered relevant in an evaluation; (ii) the sources of valuation of the relevant outcomes; (iii) the basis of weighting of relevant outcomes and (iv) interpersonal comparisons. We conclude that these differences are substantive. (C) 2007 Elsevier B.V. All rights reserved
On the link between rotation, chromospheric activity and Li abundance in subgiant stars
The connection rotation-CaII emission flux-lithium abundance is analyzed for
a sample of bona fide subgiant stars, with evolutionary status determined from
HIPPARCOS trigonometric parallax measurements and from the Toulouse-Geneva
code.Comment: 9 pages, 8 figure
HST/FOS Eclipse Observations of the Nova-like Cataclysmic Variable UX Ursae Majoris
[abridged abstract]
We present and analyze Hubble Space Telescope observations of the eclipsing
nova-like cataclysmic variable UX UMa obtained with the Faint Object
Spectrograph. Two eclipses each were observed with the G160L grating (covering
the ultraviolet waveband) in August of 1994 and with the PRISM (covering the
near-ultraviolet to near-infrared) in November of the same year. The system was
50% brighter in November than in August, which, if due to a change in the
accretion rate, indicates a fairly substantial increase in Mdot_acc by >~ 50%.
Model disk spectra constructed as ensembles of stellar atmospheres provide
poor descriptions of the observed post-eclipse spectra, despite the fact that
UX UMa's light should be dominated by the disk at this time. Suitably scaled
single temperature model stellar atmospheres with T_eff = 12,500-14,500 K
actually provide a better match to both the ultraviolet and optical
post-eclipse spectra. Evidently, great care must be taken in attempts to derive
accretion rates from comparisons of disk models to observations.
One way to reconcile disk models with the observed post-eclipse spectra is to
postulate the presence of a significant amount of optically thin material in
the system. Such an optically thin component might be associated with the
transition region (``chromosphere'') between the disk photosphere and the fast
wind from the system, whose presence has been suggested by Knigge & Drew
(1997).Comment: 35 pages, including 12 figures; to appear in the ApJ (Vol. 499
An optimized BSCCO/Ag resonator coil for utility use
AC coils made with BSCCO-2223/Ag tapes and operating in liquid nitrogen have a potential for power related applications, e.g., inductors, transformers and current limiters. High-Tc tapes are available from several producers, while access to the coil building know-help is still rather limited, The relevant knowledge and technology suitable for making HTS coils for 50-60 Hz operation is being developed as a part of the current project. To verify the technology, several test solenoids and a first full-scale sub-coil have been manufactured. Electromagnetic, thermal and mechanical analysis of the coils is performed. The electromagnetic analysis focuses on the reduction of the radial magnetic field component in the windings. Voltage-current characteristics and the AC loss data obtained from relevant short sample measurements are applied. A good agreement between calculated and measured V-I curves and losses of the coils is found. A remarkable increase of the critical current and the reduction of the AC loss at the coil edges are predicted and confirmed experimentally. With the losses defined, thermal analysis and optimization of the coil structure are performed numerically followed by measurements for verification. The paper reports on the series of coils developed and explains the features of the projec
On coalgebras with internal moves
In the first part of the paper we recall the coalgebraic approach to handling
the so-called invisible transitions that appear in different state-based
systems semantics. We claim that these transitions are always part of the unit
of a certain monad. Hence, coalgebras with internal moves are exactly
coalgebras over a monadic type. The rest of the paper is devoted to supporting
our claim by studying two important behavioural equivalences for state-based
systems with internal moves, namely: weak bisimulation and trace semantics.
We continue our research on weak bisimulations for coalgebras over order
enriched monads. The key notions used in this paper and proposed by us in our
previous work are the notions of an order saturation monad and a saturator. A
saturator operator can be intuitively understood as a reflexive, transitive
closure operator. There are two approaches towards defining saturators for
coalgebras with internal moves. Here, we give necessary conditions for them to
yield the same notion of weak bisimulation.
Finally, we propose a definition of trace semantics for coalgebras with
silent moves via a uniform fixed point operator. We compare strong and weak
bisimilation together with trace semantics for coalgebras with internal steps.Comment: Article: 23 pages, Appendix: 3 page
Explanation of the activity sensitivity of Mn I 5394.7 \AA
There is a long-standing controversy concerning the reason why the Mn I
5394.7 A line in the solar irradiance spectrum brightens more at larger
activity than most other photospheric lines. The claim that this activity
sensitivity is caused by spectral interlocking to chromospheric emission in Mg
II h & k is disputed.
Classical one-dimensional modeling is used for demonstration; modern
three-dimensional MHD simulation for verification and analysis.
The Mn I 5394.7 A line thanks its unusual sensitivity to solar activity to
its hyperfine structure. This overrides the thermal and granular Doppler
smearing through which the other, narrower, photospheric lines lose such
sensitivity. We take the nearby Fe I 5395.2 A line as example of the latter and
analyze the formation of both lines in detail to demonstrate and explain
granular Doppler brightening. We show that this affects all narrow lines.
Neither the chromosphere nor Mg II h & k play a role, nor is it correct to
describe the activity sensitivity of Mn I 5394.7 A through plage models with
outward increasing temperature contrast.
The Mn I 5394.7 A line represents a proxy diagnostic of strong-field magnetic
concentrations in the deep solar photosphere comparable to the G band and the
blue wing of H-alpha, but not a better one than these. The Mn I lines are more
promising as diagnostic of weak fields in high-resolution Stokes polarimetry.Comment: 12 pages, 8 figures, accepted by A&
A Kleene theorem for polynomial coalgebras
For polynomial functors G, we show how to generalize the classical notion of regular expression to G-coalgebras. We introduce a language of expressions for describing elements of the final G-coalgebra and, analogously to Kleeneâs theorem, we show the correspondence between expressions and finite G-coalgebras
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