4,043 research outputs found
Retail centres: it's time to make them convenient
Purpose - The purpose of this paper is to explore the influence of time convenience on shopping behaviour in the light of a time scarcity phenomenon that is reported to have reached epidemic proportions in many markets. Design/methodology/approach - The paper begins with a survey of consumer households, examining the importance shoppers assign to time convenience. This is followed by a supply-side comparison of malls and shopping strips against the attributes of time convenience. Findings - The results indicate that time convenience has a salient influence on consumers' patronage behaviour, and that malls and strips differ in their provision of this key attribute. Practical implications - Retail planners must give serious thought to creating retail environments that allow shoppers to "buy" time. Providing time convenience via one-stop shopping, extended trading hours, proximity to home or work and enclosure offers one such strategy for the shopping mall and shopping strip. Originality/value - The focus on convenience provides practitioners with a strategic alternative to hedonic strategies. It is also one of the first studies to investigate retail centre patronage from both a demand-and supply-side perspective
On the orbital period of the magnetic Cataclysmic Variable HS 0922+1333
Context: The object HS 0922+1333 was visited briefly in 2002 in a mini survey
of low accretion rate polars (LARPs) in order to test if they undergo high
luminosity states similar to ordinary polars. On the basis of that short
observation the suspicion arose that the object might be an asynchronous polar
(Tovmassian et al. 2004). The disparity between the presumed orbital and spin
period appeared to be quite unusual. Aims: We performed follow-up observations
of the object to resolve the problem. Methods: New simultaneous spectroscopic
and photometric observations spanning several years allowed measurements of
radial velocities of emission and absorption lines from the secondary star and
brightness variations due to synchrotron emission from the primary. Results:
New observations show that the object is actually synchronous and its orbital
and spin period are equal to 4.04 hours. Conclusions: We identify the source of
confusion of previous observations to be a high velocity component of emission
line arousing from the stream of matter leaving L1 point.Comment: 5 pages, 5 figures, accepted for publication in Astronomy &
Astrophysic
Aging and memory properties of topologically frustrated magnets
The model 2d kagome system (H3O)Fe3(SO4)2(OH)6 and the 3d pyrochlore Y2Mo2O7
are two well characterized examples of low-disordered frustrated
antiferromagnets which rather then condensing into spin liquid have been found
to undergo a freezing transition with spin glass-like properties. We explore
more deeply the comparison of their properties with those of spin glasses, by
the study of characteristic rejuvenation and memory effects in the
non-stationary susceptibility. While the pyrochlore shows clear evidence for
these non-trivial effects, implying temperature selective aging, that is
characteristic of a wide hierarchical distribution of equilibration processes,
the kagome system does n not show clearly these effects. Rather, it seems to
evolve towards the same final state independently of temperature.Comment: submitted for the proceedings of the 46th MMM conference (Seattle,
2001
WIYN Open Cluster Study XI: WIYN 3.5m Deep Photometry of M35 (NGC 2168)
We present deep BVI observations of the core of M35 and a nearby comparison
field obtained at the WIYN 3.5m telescope under excellent seeing. These
observations display the lower main sequence in BV and VI CMDs down to V = 23.3
and 24.6, respectively. At these faint magnitudes background field stars are
far more numerous than the cluster stars, yet by using a smoothing technique
and CMD density distribution subtraction we recover the cluster fiducial main
sequence and luminosity function to V = 24.6. We find the location of the main
sequence in these CMDs to be consistent with earlier work on other open
clusters, specifically NGC 188, NGC 2420, and NGC 2477. We compare these open
cluster fiducial sequences to stellar models by Baraffe et al. (1998), Siess et
al. (2000), Girardi et al. (2000), and Yi et al. (2001) and find that the
models are too blue in both B-V and V-I for stars below ~0.4 Mo. M35 contains
stars to the limit of the extracted main sequence, at M ~ 0.10-0.15 Mo,
suggesting that M35 may harbor a large number of brown dwarfs, which should be
easy targets for near-IR instrumentation on 8-10m telescopes. We also identify
a new candidate white dwarf in M35 at V = 21.36 +- 0.01. Depending on which WD
models are used to interpret this cluster candidate, it is either a very high
mass WD (1.05 +- 0.05 Mo) somewhat older (0.19-0.26 Gyr, 3-4 sigma) than our
best isochrone age (150 Myr), or it is a modestly massive WD (0.67-0.78 Mo)
much too old (0.42-0.83 Gyr) to belong to the cluster.Comment: 28 pages + 24 figures; to be published in the Sept, 2002 A
An empirical initial-final mass relation from hot, massive white dwarfs in NGC 2168 (M35)
The relation between the zero-age main sequence mass of a star and its
white-dwarf remnant (the initial-final mass relation) is a powerful tool for
exploration of mass loss processes during stellar evolution. We present an
empirical derivation of the initial-final mass relation based on spectroscopic
analysis of seven massive white dwarfs in NGC 2168 (M35). Using an internally
consistent data set, we show that the resultant white dwarf mass increases
monotonically with progenitor mass for masses greater than 4 solar masses, one
of the first open clusters to show this trend. We also find two massive white
dwarfs foreground to the cluster that are otherwise consistent with cluster
membership. These white dwarfs can be explained as former cluster members
moving steadily away from the cluster at speeds of <~0.5 km/s since their
formation and may provide the first direct evidence of the loss of white dwarfs
from open clusters. Based on these data alone, we constrain the upper mass
limit of WD progenitors to be >=5.8 solar masses at the 90% confidence level
for a cluster age of 150 Myr.Comment: 14 pages, 3 figures. Accepted for publication in the Astrophysical
Journal Letters. Contains some acknowledgements not in accepted version (for
space reasons), otherwise identical to accepted versio
Pulsation Period Changes as a Tool to Identify Pre-Zero Age Horizontal Branch Stars
One of the most dramatic events in the life of a low-mass star is the He
flash, which takes place at the tip of the red giant branch (RGB) and is
followed by a series of secondary flashes before the star settles into the
zero-age horizontal branch (ZAHB). Yet, no stars have been positively
identified in this key evolutionary phase, mainly for two reasons: first, this
pre-ZAHB phase is very short compared to other major evolutionary phases in the
life of a star; and second, these pre-ZAHB stars are expected to overlap the
loci occupied by asymptotic giant branch (AGB), HB and RGB stars observed in
the color-magnitude diagram (CMD). We investigate the possibility of detecting
these stars through stellar pulsations, since some of them are expected to
rapidly cross the Cepheid/RR Lyrae instability strip in their route from the
RGB tip to the ZAHB, thus becoming pulsating stars along the way. As a
consequence of their very high evolutionary speed, some of these stars may
present anomalously large period change rates. We constructed an extensive grid
of stellar models and produced pre-ZAHB Monte Carlo simulations appropriate for
the case of the Galactic globular cluster M3 (NGC 5272), where a number of RR
Lyrae stars with high period change rates are found. Our results suggest that
some -- but certainly not all -- of the RR Lyrae stars in M3 with large period
change rates are in fact pre-ZAHB pulsators.Comment: Conference Proceedings HELAS Workshop on 'Synergies between solar and
stellar modelling', Rome, June 2009, Astrophys. Space Sci., in the pres
Static Critical Behavior of the Spin-Freezing Transition in the Geometrically Frustrated Pyrochlore Antiferromagnet Y2Mo2O7
Some frustrated pyrochlore antiferromagnets, such as Y2Mo2O7, show a
spin-freezing transition and magnetic irreversibilities below a temperature Tf
similar to what is observed nonlinear magnetization measurements on Y2Mo2O7
that provide strong evidence that there is an underlying thermodynamic phase
transition at Tf, which is characterized by critical exponents \gamma \approx
2.8 and \beta \approx 0.8. These values are typical of those found in random
spin glasses, despite the fact that the level of random disorder in Y2Mo2O7 is
immeasurably small.Comment: Latex file, calls for 4 encapsulated postscript figures (included).
Submitted to Phys. Rev. Letters
Is mass loss along the red giant branch of globular clusters sharply peaked? The case of M3
There is a growing evidence that several globular clusters must contain
multiple stellar generations, differing in helium content. This hypothesis has
helped to interpret peculiar unexplained features in their horizontal branches.
In this framework we model the peaked distribution of the RR Lyr periods in M3,
that has defied explanation until now. At the same time, we try to reproduce
the colour distribution of M3 horizontal branch stars. We find that only a very
small dispersion in mass loss along the red giant branch reproduces with good
accuracy the observational data. The enhanced and variable helium content among
cluster stars is at the origin of the extension in colour of the horizontal
branch, while the sharply peaked mass loss is necessary to reproduce the
sharply peaked period distribution of RR Lyr variables. The dispersion in mass
loss has to be <~ 0.003 Msun, to be compared with the usually assumed values of
~0.02 Msun. This requirement represents a substantial change in the
interpretation of the physical mechanisms regulating the evolution of globular
cluster stars.Comment: Accepted for publication in The Astrophysical Journa
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