Optical Lattice Trap for Kerr Solitons

We show theoretically and numerically that dichromatic pumping of a nonlinear microresonator by two continuous wave coherent optical pumps creates an optical lattice trap that results in the localization of intra-cavity Kerr solitons with soliton positions defined by the beat frequency of the pumps. This phenomenon corresponds to the stabilization of the Kerr frequency comb repetition rate. The locking of the second pump, through adiabatic tuning of its frequency, to the comb generated by the first pump allows transitioning to single-soliton states, manipulating the position of Kerr solitons in the cavity, and tuning the frequency comb repetition rate within the locking range. It also explains soliton crystal formation in resonators supporting a dispersive wave emitted as a result of higher-order group velocity dispersion or avoided mode crossing. We show that dichromatic pumping by externally stabilized pumps can be utilized for stabilization of microresonator-based optical frequency combs when the comb span does not cover an octave or a significant fraction thereof and standard self-referencing techniques cannot be employed. Our findings have significant ramifications for high-precision applications of optical frequency combs in spectrally pure signal generation, metrology, and timekeeping.Comment: 13 pages, 12 figure

The effect of 12 weeks Anethum graveolens (dill) on metabolic markers in patients with metabolic syndrome; A randomized double blind controlled trial

Background: The clustering of metabolic abnormalities defined as metabolic syndrome is now both a public health and a clinical problem .While interest in herbal medicine has greatly increased, lack of human evidence to support efficacies shown in animals does exist. This clinical trial study designed to investigate whether herbal medicine, Anethum graveolens (dill) extract, could improve metabolic components in patients with metabolic syndrome. Methods: A double-blind, randomized, placebo-controlled trial using a parallel design was conducted. 24 subjects who had metabolic syndrome diagnostic criteria (update of ATP III) were randomly assigned to either dill extract (n = 12) or placebo (n = 12) for 3 months. Results: Across lipid component of metabolic syndrome, no significant differences in triglyceride (TG) concentration and high density lipoprotein cholesterol were seen between the two groups. However TG improved significantly from baseline (257.0 vs. 201.5p = 0.01) with dill treatment but such a significant effect was not observed in placebo group. Moreover, no significant differences in waist circumference, blood pressure and fasting blood sugar were seen between two groups after 3 months follow up period. Conclusion: In this small clinical trial in patients with metabolic syndrome, 12 weeks of dill extract treatment had a beneficial effect in terms of reducing TG from baseline. However dill treatment was not associated with a significant improvement in metabolic syndrome related markers compared to control group. Larger studies might be required to prove the efficacy and safety of long-Term administration of dill to resolve metabolic syndrome components. © 2012 Mansouri et al.; licensee BioMed Central Ltd

Analysing the effect of lean on the performance of NPD projects using system dynamics modelling

To be able to survive in today’s fast-changing market environment companies are looking for innovative ways to improve the performance of their new product development (NPD) processes. However, uncertainty and rework are among characteristics of NPD which make them difficult to manage. Implementing lean in NPD is an innovative approach to address this issue. Using system dynamics approach to model set-based concurrent engineering as a fundamental element of lean product development, this paper shows the positive effect on of adopting this strategy on the time, cost and quality of NPD projects, in comparison with the traditional point-based design

The effect of Lean implementation on the efficiency and effectiveness of new product development processes

Although increasing the new product development speed and improving its cost effectiveness as well as enhancing the process quality have been at the centre of attention of many companies, there is still significant opposition to the 'better, faster and cheaper' paradigm. Improvement of new product development processes using Lean principles has been claimed to be an effective way to reach to this goal. In this conceptual paper, first the efficiency and effectiveness in new product development processes and the key components of Lean product development has been defined, then, an introduction to modelling the process based on System Dynamics, to develop the interrelationships between Lean components and performance measures, has been discussed

Electric-field-induced nematic-cholesteric transition and 3-D director structures in homeotropic cells

We study the phase diagram of director structures in cholesteric liquid crystals of negative dielectric anisotropy in homeotropic cells of thickness d which is smaller than the cholesteric pitch p. The basic control parameters are the frustration ratio d/p and the applied voltage U. Fluorescence Confocal Polarising Microscopy allows us to directly and unambiguously determine the 3-D director structures. The results are of importance for potential applications of the cholesteric structures, such as switchable gratings and eyewear with tunable transparency based.Comment: Will be published in Physical Review

Whirl mappings on generalised annuli and the incompressible symmetric equilibria of the dirichlet energy

In this paper we show a striking contrast in the symmetries of equilibria and extremisers of the total elastic energy of a hyperelastic incompressible annulus subject to pure displacement boundary conditions.Indeed upon considering the equilibrium equations, here, the nonlinear second order elliptic system formulated for the deformation u=(u1,…,uN) : EL[u,X]=⎧⎩⎨⎪⎪Δu=div(P(x)cof∇u)det∇u=1u≡φinX,inX,on∂X, where X is a finite, open, symmetric N -annulus (with N≥2 ), P=P(x) is an unknown hydrostatic pressure field and φ is the identity mapping, we prove that, despite the inherent rotational symmetry in the system, when N=3 , the problem possesses no non-trivial symmetric equilibria whereas in sharp contrast, when N=2 , the problem possesses an infinite family of symmetric and topologically distinct equilibria. We extend and prove the counterparts of these results in higher dimensions by way of showing that a similar dichotomy persists between all odd vs. even dimensions N≥4 and discuss a number of closely related issues

Population dynamics of the Spanish mackerel (Scomberomorus commerson) in coastal waters of Oman Sea

Length composition data of narrow-barred Spanish mackerel, Scomberomorus commerson (Lacepede 1800), landed between April 2002 to March 2004, were monthly used to estimate the growth, mortality and exploitation parameters of the stock. Maximum fork length and weight were 170 cm and 38 kg, respectively. Nonlinear least square fitting provided a complete set of von Bertalanffy growth estimates: L¥=178 cm (FL); K=0.28 and to= -0.36 years. The estimated value of total mortality based on length converted catch curve using these growth parameters is Z=0.95 year-I. Natural mortality based on growth parameters and mean environmental temperature (T=26.5°C) is M=0.36 year-1. Furthermore, the annual instantaneous fishing mortality rate of 0.59 year-1 was by far in excess of the precautionary target (Fopt=0.18 year-1) and limit (Flimit=0.24 year-1) biological reference points, indicating that the resource is heavily over-exploited and the management of this species should be implanted rapidly if they are to remain sustainable

Mappings of least Dirichlet energy and their Hopf differentials

The paper is concerned with mappings between planar domains having least Dirichlet energy. The existence and uniqueness (up to a conformal change of variables in the domain) of the energy-minimal mappings is established within the class $\bar{\mathscr H}_2(X, Y)$ of strong limits of homeomorphisms in the Sobolev space $W^{1,2}(X, Y)$, a result of considerable interest in the mathematical models of Nonlinear Elasticity. The inner variation leads to the Hopf differential $h_z \bar{h_{\bar{z}}} dz \otimes dz$ and its trajectories. For a pair of doubly connected domains, in which $X$ has finite conformal modulus, we establish the following principle: A mapping $h \in \bar{\mathscr H}_2(X, Y)$ is energy-minimal if and only if its Hopf-differential is analytic in $X$ and real along the boundary of $X$. In general, the energy-minimal mappings may not be injective, in which case one observes the occurrence of cracks in $X$. Nevertheless, cracks are triggered only by the points in the boundary of $Y$ where $Y$ fails to be convex. The general law of formation of cracks reads as follows: Cracks propagate along vertical trajectories of the Hopf differential from the boundary of $X$ toward the interior of $X$ where they eventually terminate before making a crosscut.Comment: 51 pages, 4 figure