267 research outputs found
Quantum Potential and Symmetries in Extended Phase Space
The behavior of the quantum potential is studied for a particle in a linear
and a harmonic potential by means of an extended phase space technique. This is
done by obtaining an expression for the quantum potential in momentum space
representation followed by the generalization of this concept to extended phase
space. It is shown that there exists an extended canonical transformation that
removes the expression for the quantum potential in the dynamical equation. The
situation, mathematically, is similar to disappearance of the centrifugal
potential in going from the spherical to the Cartesian coordinates that changes
the physical potential to an effective one. The representation where the
quantum potential disappears and the modified Hamilton-Jacobi equation reduces
to the familiar classical form, is one in which the dynamical equation turns
out to be the Wigner equation.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and
Applications) at http://www.emis.de/journals/SIGMA
Operator Gauge Symmetry in QED
In this paper, operator gauge transformation, first introduced by Kobe, is
applied to Maxwell's equations and continuity equation in QED. The gauge
invariance is satisfied after quantization of electromagnetic fields. Inherent
nonlinearity in Maxwell's equations is obtained as a direct result due to the
nonlinearity of the operator gauge transformations. The operator gauge
invariant Maxwell's equations and corresponding charge conservation are
obtained by defining the generalized derivatives of the first and second kinds.
Conservation laws for the real and virtual charges are obtained too. The
additional terms in the field strength tensor are interpreted as electric and
magnetic polarization of the vacuum.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and
Applications) at http://www.emis.de/journals/SIGMA
An empirical study to determine the critical success factors on customer retention: A case study of Iranian banking sector
One of the most important strategic issues for any enterprise is to create and deliver superior value for its customers and provide enough evidences to convince them not to choose another competitive. In this study, we study the effects of customer value, customer satisfaction and customer loyalty on customer retention. The results indicate that all aspects of the customer value have positive relationships with customer satisfaction but only emotional value has a positive and direct relationship with customer loyalty. The study confirms that while none of customer value aspects has direct and positive relationship with customer retention, both customer satisfaction and customer loyalty positively and directly affect customer retention
The application of water cycle algorithm to portfolio selection
Portfolio selection is one of the most vital financial problems in
literature. The studied problem is a nonlinear multi-objective problem
which has been solved by a variety of heuristic and metaheuristic
techniques. In this article, a metaheuristic optimiser, the multiobjective
water cycle algorithm (MOWCA), is represented to find
efficient frontiers associated with the standard mean-variance (MV)
portfolio optimisation model. The inspired concept of WCA
is based on the simulation of water cycle process in the nature.
Computational results are obtained for analyses of daily data for
the period January 2012 to December 2014, including S&P100 in
the US, Hang Seng in Hong Kong, FTSE100 in the UK, and DAX100
in Germany. The performance of the MOWCA for solving portfolio
optimisation problems has been evaluated in comparison with
other multi-objective optimisers including the NSGA-II and multiobjective
particle swarm optimisation (MOPSO). Four well-known
performance metrics are used to compare the reported optimisers.
Statistical optimisation results indicate that the applied MOWCA is an
efficient and practical optimiser compared with the other methods
for handling portfolio optimisation problems
A first case of tinea imbricata from Iran
Tinea imbricata is an uncommon dermatophytosis caused by the anthropophilic
dermatophyte Trichophyton concentricum in endemic regions. In the present study, a 10-
year-old girl was examined for tinea imbricata. Microscopic examination revealed the
presence of hyaline, septate, branching hyphae and its cultures on Sabouraud dextrose
agar yielded T. concentricum. The patient responded to treatment with oral terbinafine
250mg/day topical clotrimazole (1% ointment), topical miconazole (2% cream) two
times daily and potassium permanganate for daily washing for four weeks. In the
present study, we reported the first case of tinea imbricate from Iran
Analysis of Task-Based Language Teaching (TBLT) In the process of teaching and learning the phonetic system of the Arabic language
One of the main challenges in teaching Arabic language is teaching the phonetic system in a systematic method Because language learners need to understand different phonetic levels through practical training in order to establish communicate purposefully and interact properly with native speakers, so that in addition to acceptable and comprehensible pronunciation in their interactions, they can provide correct verbal and non-verbal reactions to the spoken word. Therefore, the present study intends to study the task-based approach in teaching the Arabic sounds with a descriptive-comparative method. The results indicate that main difference between Persian sounds and Arabic is in the fourth level of difficulty (θ /ħ /ð /sˤ /dˤ /tˤ /ðˤ /ʕ /ɣ) and then in the third level (z /s /ʃ /dʒ /k /q /w). the task-based approach with the “pre-task phase” makes the learner cognitively aware of these differences as well as the level of Suprasegmental and creates the necessary preparations, then in the stage During task with emphasis on all aspects of language at the level of Segmental and suprasegmental of speech and behaviorally reinforce them by engaging the learner in applied tasks based on their needs in communication situations, emphasizing pivotal interaction. So that by using real tasks and in the context of the audio text, in addition to placing the learner in areal communication situation, the challenge of changing the properties of sounds, is solved by accompaniment, and by stabilizing the cognitive dimension and repetition of tasks in quasi-real situations in the post-task phase. In creases the communication ability of language learners. Therefore, it can be said that the task-based approach is quite suitable for use in teaching the phonetic system of the Arabic language
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