1,161 research outputs found
Constructing an Index for Brand Equity: A Hospital Example
If two hospitals are providing identical services in all respects, except for the brand name, why are customers willing to pay more for one hospital than the other? That is, the brand name is not just a name, but a name that contains value (brand equity). Brand equity is the value that the brand name endows to the product, such that consumers are willing to pay a premium price for products with the particular brand name. Accordingly, a company needs to manage its brand carefully so that its brand equity does not depreciate. Although measuring brand equity is important, managers have no brand equity index that is psychometrically robust and parsimonious enough for practice. Indeed, index construction is quite different from conventional scale development. Moreover, researchers might still be unaware of the potential appropriateness of formative indicators for operationalizing particular constructs. Towards this end, drawing on the brand equity literature and following the index construction procedure, this study creates a brand equity index for a hospital. The results reveal a parsimonious five-indicator brand equity index that can adequately capture the full domain of brand equity. This study also illustrates the differences between index construction and scale development
A Two-stage Architecture for Stock Price Forecasting by Integrating Self-Organizing Map and Support Vector Regression
Stock price prediction has attracted much attention from both practitioners and researchers. However, most studies in this area ignored the non-stationary nature of stock price series. That is, stock price series do not exhibit identical statistical properties at each point of time. As a result, the relationships between stock price series and their predictors are quite dynamic. It is challenging for any single artificial technique to effectively address this problematic characteristics in stock price series. One potential solution is to hybridize different artificial techniques. Towards this end, this study employs a two-stage architecture for better stock price prediction. Specifically, the self-organizing map (SOM) is first used to decompose the whole input space into regions where data points with similar statistical distributions are grouped together, so as to contain and capture the non-stationary property of financial series. After decomposing heterogeneous data points into several homogenous regions, support vector regression (SVR) is applied to forecast financial indices. The proposed technique is empirically tested using stock price series from seven major financial markets. The results show that the performance of stock price prediction can be significantly enhanced by using the two-stage architecture in comparison with a single SVR model
Innovate with Complex Information Technologies: A Theoretical Model and Empirical Examination
Complex information technologies (CITs), such as ERP packages, have become the core component of modern organizations. Corporate investments in CITs have soared to a record high. Firms need to creatively apply the technologies in order to adapt to the ever-changing environments and realize the full potential of the technologies. We approach this issue from the perspective of âInnovate with ITâ, a post-acceptance usage behavior that describes innovative use of information technologies to support individual task performances. Drawing upon the IS Continuance (ISC) model, as well as the managerial and individual factors that facilitate higher level IT use, a model is theoretically developed to understand employeesâ novel use of CITs. A field study was conducted in a large manufacturing firm using ERP packages to empirically validate the model. The results suggest that the ISC model, personal propensity toward IT innovations, and management support jointly nurture employeesâ creative use of complex technologies
A review of Monte Carlo simulations of polymers with PERM
In this review, we describe applications of the pruned-enriched Rosenbluth
method (PERM), a sequential Monte Carlo algorithm with resampling, to various
problems in polymer physics. PERM produces samples according to any given
prescribed weight distribution, by growing configurations step by step with
controlled bias, and correcting "bad" configurations by "population control".
The latter is implemented, in contrast to other population based algorithms
like e.g. genetic algorithms, by depth-first recursion which avoids storing all
members of the population at the same time in computer memory. The problems we
discuss all concern single polymers (with one exception), but under various
conditions: Homopolymers in good solvents and at the point, semi-stiff
polymers, polymers in confining geometries, stretched polymers undergoing a
forced globule-linear transition, star polymers, bottle brushes, lattice
animals as a model for randomly branched polymers, DNA melting, and finally --
as the only system at low temperatures, lattice heteropolymers as simple models
for protein folding. PERM is for some of these problems the method of choice,
but it can also fail. We discuss how to recognize when a result is reliable,
and we discuss also some types of bias that can be crucial in guiding the
growth into the right directions.Comment: 29 pages, 26 figures, to be published in J. Stat. Phys. (2011
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A method for characterizing photon radiation fields
Uncertainty in dosimetric and exposure rate measurements can increase in areas where multi-directional and low-energy photons (< 100 keV) exist because of variations in energy and angular measurement response. Also, accurate measurement of external exposures in spatially non-uniform fields may require multiple dosimetry. Therefore, knowledge of the photon fields in the workplace is required for full understanding of the accuracy of dosimeters and instruments, and for determining the need for multiple dosimeters. This project was designed to develop methods to characterize photon radiation fields in the workplace, and to test the methods in a plutonium facility. The photon field at selected work locations was characterized using TLDs and a collimated NaI(Tl) detector from which spatial variations in photon energy distributions were calculated from measured spectra. Laboratory results showed the accuracy and utility of the method. Field measurement results combined with observed work patterns suggested the following: (1) workers are exposed from all directions, but not isotropically, (2) photon energy distributions were directionally dependent, (3) stuffing nearby gloves into the glovebox reduced exposure rates significantly, (4) dosimeter placement on the front of the chest provided for a reasonable estimate of the average dose equivalent to workers` torsos, (5) justifiable conclusions regarding the need for multiple dosimetry can be made using this quantitative method, and (6) measurements of the exposure rates with ionization chambers pointed with open beta windows toward the glovebox provided the highest measured rates, although absolute accuracy of the field measurements still needs to be assessed
Volume Stabilization via Corrections in Type IIB Theory with Fluxes
We consider the Type IIB string theory in the presence of various extra
-brane pairs compactified on a warped Calabi-Yau threefold that
admits a conifold singularity. We demonstrate that the volume modulus can be
stabilized perturbatively at a non-supersymmetric vacuum by the
effective potential that includes the stringy correction
obtained by Becker {\it et al.} together with a combination of positive tension
and anomalous negative tension terms generated by the additional
7-brane-antibrane pairs.Comment: 20 pages, 4 figures, parts of introduction and conclusions are
modifie
Axionic D3-D7 Inflation
We study the motion of a D3 brane moving within a Type IIB string vacuum
compactified to 4D on K3 x T_2/Z_2 in the presence of D7 and O7 planes. We work
within the effective 4D supergravity describing how the mobile D3 interacts
with the lightest bulk moduli of the compactification, including the effects of
modulus-stabilizing fluxes. We seek inflationary solutions to the resulting
equations, performing our search numerically in order to avoid resorting to
approximate parameterizations of the low-energy potential. We consider
uplifting from D-terms and from the supersymmetry-breaking effects of anti-D3
branes. We find examples of slow-roll inflation (with anti-brane uplifting)
with the mobile D3 moving along the toroidal directions, falling towards a
D7-O7 stack starting from the antipodal point. The inflaton turns out to be a
linear combination of the brane position and the axionic partner of the K3
volume modulus, and the similarity of the potential along the inflaton
direction with that of racetrack inflation leads to the prediction n_s \le 0.95
for the spectral index. The slow roll is insensitive to most of the features of
the effective superpotential, and requires a one-in-10^4 tuning to ensure that
the torus is close to square in shape. We also consider D-term inflation with
the D3 close to the attractive D7, but find that for a broad (but not
exhaustive) class of parameters the conditions for slow roll tend to
destabilize the bulk moduli. In contrast to the axionic case, the best
inflationary example of this kind requires the delicate adjustment of potential
parameters (much more than the part-per-mille level), and gives inflation only
at an inflection point of the potential (and so suffers from additional
fine-tuning of initial conditions to avoid an overshoot problem).Comment: 29 pages, 5 figure
Preventive effects of Spirulina platensis on skeletal muscle damage under exercise-induced oxidative stress
The effects of spirulina supplementation on preventing skeletal muscle damage on untrained human beings were examined. Sixteen students volunteered to take Spirulina platensis in addition to their normal diet for 3-weeks. Blood samples were taken after finishing the Bruce incremental treadmill exercise before and after treatment. The results showed that plasma concentrations of malondialdehyde (MDA) were significantly decreased after supplementation with spirulina (P < 0.05). The activity of blood superoxide dismutase (SOD) was significantly raised after supplementation with spirulina or soy protein (P < 0.05). Both of the blood glutathione peroxidaes (GP (x) ) and lactate dehydrogenase (LDH) levels were significantly different between spirulina and soy protein supplementation by an ANCOVA analysis (P < 0.05). In addition, the lactate (LA) concentration was higher and the time to exhaustion (TE) was significantly extended in the spirulina trail (P < 0.05). These results suggest that ingestion of S. platensis showed preventive effect of the skeletal muscle damage and that probably led to postponement of the time of exhaustion during the all-out exercise
Spontaneous Creation of Inflationary Universes and the Cosmic Landscape
We study some gravitational instanton solutions that offer a natural
realization of the spontaneous creation of inflationary universes in the brane
world context in string theory. Decoherence due to couplings of higher
(perturbative) modes of the metric as well as matter fields modifies the
Hartle-Hawking wavefunction for de Sitter space. Generalizing this new
wavefunction to be used in string theory, we propose a principle in string
theory that hopefully will lead us to the particular vacuum we live in, thus
avoiding the anthropic principle. As an illustration of this idea, we give a
phenomenological analysis of the probability of quantum tunneling to various
stringy vacua. We find that the preferred tunneling is to an inflationary
universe (like our early universe), not to a universe with a very small
cosmological constant (i.e., like today's universe) and not to a 10-dimensional
uncompactified de Sitter universe. Such preferred solutions are interesting as
they offer a cosmological mechanism for the stabilization of extra dimensions
during the inflationary epoch.Comment: 52 pages, 7 figures, 1 table. Added discussion on supercritical
string vacua, added reference
Kahler Moduli Inflation
We show that under general conditions there is at least one natural
inflationary direction for the Kahler moduli of type IIB flux
compactifications. This requires a Calabi-Yau which has h^{2,1}>h^{1,1}>2 and
for which the structure of the scalar potential is as in the recently found
exponentially large volume compactifications. We also need - although these
conditions may be relaxed - at least one Kahler modulus whose only
non-vanishing triple-intersection is with itself and which appears by itself in
the non-perturbative superpotential. Slow-roll inflation then occurs without a
fine tuning of parameters, evading the eta problem of F-term inflation. In
order to obtain COBE-normalised density perturbations, the stabilised volume of
the Calabi-Yau must be O(10^5-10^7) in string units, and the inflationary scale
M_{infl} ~ 10^{13} GeV. We find a robust model independent prediction for the
spectral index of 1 - 2/N_e = 0.960 - 0.967, depending on the number of
efoldings.Comment: 17 pages, 1 figure; v2. references adde
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