398 research outputs found

    Bakhtiari, Leskinen and Torma Reply

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    This is a Reply to: Comment on "Spectral Signatures of the Fulde-Ferrell-Larkin-Ovchinnikov Order Parameter in One-Dimensional Optical Lattices" R. A. Molina J. Dukelksy, and P. Schmitteckert, Phys. Rev. Lett. 102, 168901 (2009)Comment: 1 page, published versio

    Numerical Modelling of Wave-Induced Current and Wave Transformation in Presence of Submerged Breakwaters

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    Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

    Theory of coherent transport by an ultra-cold atomic Fermi gas through linear arrays of potential wells

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    Growing interest is being given to transport of ultra-cold atomic gases through optical lattices generated by the interference of laser beams. In this connection we evaluate the phase-coherent transport of a spin-polarized gas of fermionic atoms along linear structures made from potential wells set in four alternative types of sequence. These are periodic chains of either identical wells or pairs of different wells, and chains of pairs of wells arranged in either a Fibonacci quasi-periodic sequence or a random sequence. The transmission coefficient of fermionic matter is evaluated in a T-matrix scattering approach by describing each array through a tight-binding Hamiltonian and by reducing it to an effective dimer by means of a decimation/renormalization method. The results are discussed in comparison with those pertaining to transport by Fermi-surface electrons coupled to an outgoing lead and by an atomic Bose-Einstein condensate. Main attention is given to (i) Bloch oscillations and their mapping into alternating-current flow through a Josephson junction; (ii) interference patterns that arise on period doubling and their analogy with beam splitting in optical interferometry; (iii) localization by quasi-periodic disorder inside a Fibonacci-ordered structure of double wells; and (iv) Anderson localization in a random structure of double wells.Comment: 14 pages, 4 figure

    Spectral signatures of the Fulde-Ferrell-Larkin-Ovchinnikov order parameter in one-dimensional optical lattices

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    We address an imbalanced two-component atomic Fermi gas restricted by a one-dimensional (1D) optical lattice and an external harmonic potential, within the mean-field Bogoliubov-de Gennes (BdG) formalism. We show that characteristic features of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state are visible in the RF-spectra and in the momentum resolved photoemission spectra of the gas. Specially, Andreev states or mid-gap states can be clearly resolved, which gives a direct experimentally observable signature of the oscillating order parameter.Comment: published versio

    Effect of employee job satisfaction on organizational entrepreneurship

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    An entrepreneurial organization is always ready and able to adapt too many essential changes in the external environment, and plan their programs for changing environmental needs.This research has been done to identify the effect of job satisfaction on organizational entrepreneurship in the municipality. The methodology of the research in terms of the main strategy is a quantitative method. From the point of view of applied purpose, it is a descriptive and correlational method for executive, field, and library methods. The statistical population of this study is all 325 staff members in March 2018. The sampling method is a simple random method. The sample size was 175 people based on the Morgan table. Measurement tool in this research was a standard five-point Likert scale questionnaire and for analyzing data the Partial least squares regression (Smart PLS software) was used. Findings showed that job satisfaction (General Working Conditions, Contact with Colleagues, Salary and Benefits and Staff Loyalty) has a positive and significant effect on organizational entrepreneurship. Considering that the Cronbach's alpha value in this research is more than 0.7, it indicates the appropriate reliability of the research. The results showed that general conditions of work with severity (4.701), relationship with colleagues with severity (5.385), Salaries and benefits with severity (3.906) and loyalty of staff with severity (5.97) have a positive and significant effect on organizational entrepreneurship

    An efficient two-parametric family with memory for nonlinear equations

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    A new two-parametric family of derivative-free iterative methods for solving nonlinear equations is presented. First, a new biparametric family without memory of optimal order four is proposed. The improvement of the convergence rate of this family is obtained by using two self-accelerating parameters. These varying parameters are calculated in each iterative step employing only information from the current and the previous iteration. The corresponding R-order is 7 and the efficiency index 7(1/3) = 1.913. Numerical examples and comparison with some existing derivative-free optimal eighth-order schemes are included to confirm the theoretical results. In addition, the dynamical behavior of the designed method is analyzed and shows the stability of the scheme.The second author wishes to thank the Islamic Azad University, Hamedan Branch, where the paper was written as a part of the research plan, for financial support.Cordero Barbero, A.; Lotfi, T.; Bakhtiari, P.; Torregrosa Sánchez, JR. (2015). An efficient two-parametric family with memory for nonlinear equations. Numerical Algorithms. 68(2):323-335. doi:10.1007/s11075-014-9846-8S323335682Kung, H.T., Traub, J.F.: Optimal order of one-point and multi-point iteration. J. Assoc. Comput. Math. 21, 643–651 (1974)Cordero, A., Hueso, J.L., Martínez, E., Torregrosa, J.R.: A new technique to obtain derivative-free optimal iterative methods for solving nonlinear equation. J. Comput. Appl. Math. 252, 95–102 (2013)Cordero, A., Torregrosa, J.R., Vassileva, M.P.: Pseudocomposition: a technique to design predictor-corrector methods for systems of nonlinear equations. Appl. Math. Comput. 218, 11496–11508 (2012)Džunić, J.: On efficient two-parameter methods for solving nonlinear equations. Numer. Algorithms. 63(3), 549–569 (2013)Džunić, J., Petković, M.S.: On generalized multipoint root-solvers with memory. J. Comput. Appl. Math. 236, 2909–2920 (2012)Petković, M.S., Neta, B., Petković, L.D., Džunić, J. (ed.).: Multipoint methods for solving nonlinear equations. Elsevier (2013)Sharma, J.R., Sharma, R.: A new family of modified Ostrowski’s methods with accelerated eighth order convergence. Numer. Algorithms 54, 445–458 (2010)Soleymani, F., Shateyi, S.: Two optimal eighth-order derivative-free classes of iterative methods. Abstr. Appl. Anal. 2012(318165), 14 (2012). doi: 10.1155/2012/318165Soleymani, F., Sharma, R., Li, X., Tohidi, E.: An optimized derivative-free form of the Potra-Pták methods. Math. Comput. Model. 56, 97–104 (2012)Thukral, R.: Eighth-order iterative methods without derivatives for solving nonlinear equations. ISRN Appl. Math. 2011(693787), 12 (2011). doi: 10.5402/2011/693787Traub, J.F.: Iterative Methods for the Solution of Equations. Prentice Hall, New York (1964)Wang, X., Džunić, J., Zhang, T.: On an efficient family of derivative free three-point methods for solving nonlinear equations. Appl. Math. Comput. 219, 1749–1760 (2012)Zheng, Q., Li, J., Huang, F.: An optimal Steffensen-type family for solving nonlinear equations. Appl. Math. Comput. 217, 9592–9597 (2011)Ortega, J.M., Rheinboldt, W.G. (ed.).: Iterative Solutions of Nonlinear Equations in Several Variables, Ed. Academic Press, New York (1970)Jay, I.O.: A note on Q-order of convergence. BIT Numer. Math. 41, 422–429 (2001)Blanchard, P.: Complex Analytic Dynamics on the Riemann Sphere. Bull. AMS 11(1), 85–141 (1984)Chicharro, F., Cordero, A., Torregrosa, J.R.: Drawing dynamical and parameters planes of iterative families and methods. arXiv: 1307.6705 [math.NA

    Coherent transport in linear arrays of quantum dots: the effects of period doubling and of quasi-periodicity

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    We evaluate the phase-coherent transport of electrons along linear structures of varying length, which are made from two types of potential wells set in either a periodic or a Fibonacci quasi-periodic sequence. The array is described by a tight-binding Hamiltonian and is reduced to an effective dimer by means of a decimation-renormalization method, extended to allow for connection to external metallic leads, and the transmission coefficient is evaluated in a T-matrix scattering approach. Parallel behaviors are found for the energy dependence of the density of electron states and of the transmittivity of the array. In particular, we explicitly show that on increasing its length the periodic array undergoes a metal-insulator transition near single occupancy per dot, whereas prominent pseudo-gaps emerge away from the band center in the Fibonacci-ordered array.Comment: 11 pages, 7 figure

    Cataract surgery for congenital cataract: Endothelial cell characteristics, corneal thickness, and impact on intraocular pressure

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    Purpose: To investigate whether central corneal thickness (CCT), endothelial cell characteristics, and intraocular pressure (IOP) are affected in patients with previous congenital cataract surgery and to focus on their clinical significance. Methods: CCT and IOP measurements and specular microscopy were performed in 31 eyes of 17 cases of extracted congenital cataracts and 40 eyes of 20 age- and sex-matched participants as control group. The mean of three pachymetry measurements of the central cornea was taken as CCT. IOP was checked using an applanation tonometer. Results: The mean corneal thickness of the eyes with extracted congenital cataract (632 ± 45 μm) was significantly greater than that of the control eyes (546 ± 33 μm; p < 0.001). There was no significant difference in the corneal endothelial cell count, coefficient of variation (CV), and mean cell area (AVG) of endothelial cells between operated eyes and the control group. The mean measured IOP in the operated group (22.8 ± 3.3 mm Hg) was significantly greater than IOP in controls (14.1±1.8 mm Hg, p < 0.001). Conclusions: Although the corneas were clinically clear and there was no significant difference in endothelial characteristics of eyes with extracted congenital cataract and controls, central corneas of operated eyes were significantly thicker than those of controls. To differentiate the actual glaucoma from ocular hypertension in these patients, the central corneal thickness measurement should strongly be considered. © 2007 American Association for Pediatric Ophthalmology and Strabismus

    Central corneal thickness, corneal endothelial characteristics and intraocular pressure after pediatric cataract surgery

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    To investigate central corneal thickness (CCT), endothelial cell characteristics and intraocular pressure (IOP) in eyes with prior pediatric cataract surgery and to compare them with eyes of normal age and sex matched controls. Methods: Specular microscopy CCT and IOP measurements were performed in 31 eyes of 17 patients with prior congenital cataract extraction and 40 eyes of 20 age and sex matched subjects. The mean of three pachymetric and specular microscopic measurements were recorded. IOP was measured using Goldmann applanation tonometry. Results: Mean CCT was 632±45 μm in eyes with prior pediatric cataract surgery vs 546±33 μm in control eyes (P<0.001, independent t test and Mann Whitney U-test). Mean IOP was 22.1±3.9 mmHg in eyes with prior pediatric cataract surgery and 14.0±1.6 mmHg in the control group (P<0.001, independent t-test). There was no significant difference between the two groups in cell count, polymegethism and mean cell area of corneal endothelial cells. Conclusions: Although the corneas were clinically clear and there was no significant difference in endothelial characteristics in eyes with prior pediatric cataract surgery as compared to normal controls, central corneal thickness in the operated eyes was significantly greater. To differentiate actual glaucoma from artifactual IOP increase, CCT measurement should be performed in these patients
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