849 research outputs found
Basins of attraction for cascading maps
We study a finite uni-directional array of "cascading" or "threshold coupled"
chaotic maps. Such systems have been proposed for use in nonlinear computing
and have been applied to classification problems in bioinformatics. We describe
some of the attractors for such systems and prove general results about their
basins of attraction. In particular, we show that the basins of attraction have
infinitely many path components. We show that these components always
accumulate at the corners of the domain of the system. For all threshold
parameters above a certain value, we show that they accumulate at a Cantor set
in the interior of the domain. For certain ranges of the threshold, we prove
that the system has many attractors.Comment: 15 pages, 9 figures. To appear in International Journal of
Bifurcations and Chao
Simple Estimation of X- Trion Binding Energy in Semiconductor Quantum Wells
A simple illustrative wave function with only three variational parameters is
suggested to calculate the binding energy of negatively charged excitons (X-)
as a function of quantum well width. The results of calculations are in
agreement with experimental data for GaAs, CdTe and ZnSe quantum wells, which
differ considerably in exciton and trion binding energy. The normalized X-
binding energy is found to be nearly independent of electron-to-hole mass ratio
for any quantum well heterostructure with conventional parameters. Its
dependence on quantum well width follows an universal curve. The curve is
described by a simple phenomenological equation.Comment: 8 pages, 3 Postscript figure
Binding Energy of Charged Excitons in ZnSe-based Quantum Wells
Excitons and charged excitons (trions) are investigated in ZnSe-based quantum
well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of
magneto-optical spectroscopy. Binding energies of negatively () and positively
(X+) charged excitons are measured as functions of quantum well width, free
carrier density and in external magnetic fields up to 47 T. The binding energy
of shows a strong increase from 1.4 to 8.9 meV with decreasing quantum well
width from 190 to 29 A. The binding energies of X+ are about 25% smaller than
the binding energy in the same structures. The magnetic field behavior of and
X+ binding energies differ qualitatively. With growing magnetic field strength,
increases its binding energy by 35-150%, while for X+ it decreases by 25%.
Zeeman spin splittings and oscillator strengths of excitons and trions are
measured and discussed
A Customer Perspective on Product Eliminations: How the Removal of Products Affects Customers and Business Relationships
Regardless of the apparent need for product
eliminations, many managers hesitate to act as
they fear deleterious effects on customer satisfaction and loyalty. Other managers do
carry out product eliminations, but often fail
to consider the consequences for customers
and business relationships. Given the relevance
and problems of product eliminations, research
on this topic in general and on the
consequences for customers and business
relationships in particular is surprisingly scarce. Therefore, this empirical study explores how and to what extent the elimination of a
product negatively affects customers and
business relationships. Results indicate that
eliminating a product may result in severe
economic and psychological costs to customers,
thereby seriously decreasing customer satisfaction and loyalty. This paper also shows
that these costs are not exogenous in nature. Instead, depending on the characteristics
of the eliminated product these costs are
found to be more or less strongly driven by a
company’s behavior when implementing the
elimination at the customer interface
Escape Rates and Physically Relevant Measures for Billiards with Small Holes
We study the billiard map corresponding to a periodic Lorentz gas in
2-dimensions in the presence of small holes in the table. We allow holes in the
form of open sets away from the scatterers as well as segments on the
boundaries of the scatterers. For a large class of smooth initial
distributions, we establish the existence of a common escape rate and
normalized limiting distribution. This limiting distribution is conditionally
invariant and is the natural analogue of the SRB measure of a closed system.
Finally, we prove that as the size of the hole tends to zero, the limiting
distribution converges to the smooth invariant measure of the billiard map.Comment: 39 pages, 4 figure
Cloud Computing As a Tool for Enhancing Ecological Goals?
Cloud computing has been introduced as a promising information technology (IT) that embodies not only economic advantages in terms of increased efficiency but also ecological gains through saving energy. The latter has become particularly important in view of the rising energy costs of IT. The present study analyzes whether necessary preconditions for accepting cloud computing as a new infrastructure, such as awareness and perceived net value, exist on the part of the users. The analysis is based on a combined research framework of the theory of reasoned action (TRA) and the technology acceptance model (TAM) in a cloud computing setting. Two consumer surveys, the one to elicit beliefs and the second to gain insight into the ranking of the variables, are employed. This study uses structural equation modeling (SEM) to evaluate the hypotheses. The results indicate support for the proposed research framework. Surprisingly however, the ecological factor does not play a role in forming cloud computing intentions, regardless of prior knowledge or experience. Empirical evidence of this study suggests increasing efforts for informing actual and potential users, particularly in respect to possible ecological advantages through applying the new IT infrastructure
Relevance of the JAK2V617F mutation in patients with deep vein thrombosis of the leg
Venous thromboembolism (VTE) can be the first presenting symptom in myeloproliferative neoplasms (MPN). Studies have demonstrated a high prevalence of the JAK2V617F mutation in patients with splanchnic vein thrombosis. Fewer studies have been done in patients with thrombosis outside the splanchnic area, showing a lower prevalence although the clinical relevance of the mutation in these patients, e.g., progression to overt MPN, remains unknown. The objective of this study was to determine the effect size of JAK2V617F in prospectively collected DNA samples of patients objectively diagnosed with deep vein thrombosis (DVT) of the leg and controls without DVT, with follow-up on JAK2V617F-positive patients to assess clinical relevance. Presence of JAK2V617F was determined in DNA samples from 187 patients with DVT and 201 controls, using quantitative RT-PCR. Hematological parameters were also analyzed. All initially JAK2V617F-positive patients were reassessed. Of 187 patients with DVT, 178 were analyzed for JAK2V617F, and in four (2.3%; 95% CI 0.1–4.4), JAK2V617F was present. Of 201 controls, 198 were analyzed; one was JAK2V617F positive (0.5%; 95% CI −0.5–1.5, OR 4.5; 95% CI 0.5–40.9). None had MPN features, nor upon reassessment after a median follow-up of 68.5 months. Four JAK2V617F-positive patients with DVT and one control without DVT did not develop overt MPN after a median follow-up of nearly 6 years. Thus, in patients with non-splanchnic venous thrombosis, JAK2V617F appears not to be clinically relevant
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