Information Transmission using the Nonlinear Fourier Transform, Part I: Mathematical Tools

The nonlinear Fourier transform (NFT), a powerful tool in soliton theory and exactly solvable models, is a method for solving integrable partial differential equations governing wave propagation in certain nonlinear media. The NFT decorrelates signal degrees-of-freedom in such models, in much the same way that the Fourier transform does for linear systems. In this three-part series of papers, this observation is exploited for data transmission over integrable channels such as optical fibers, where pulse propagation is governed by the nonlinear Schr\"odinger equation. In this transmission scheme, which can be viewed as a nonlinear analogue of orthogonal frequency-division multiplexing commonly used in linear channels, information is encoded in the nonlinear frequencies and their spectral amplitudes. Unlike most other fiber-optic transmission schemes, this technique deals with both dispersion and nonlinearity directly and unconditionally without the need for dispersion or nonlinearity compensation methods. This first paper explains the mathematical tools that underlie the method.Comment: This version contains minor updates of IEEE Transactions on Information Theory, vol. 60, no. 7, pp. 4312--4328, July 201

Information Transmission using the Nonlinear Fourier Transform, Part III: Spectrum Modulation

Motivated by the looming "capacity crunch" in fiber-optic networks, information transmission over such systems is revisited. Among numerous distortions, inter-channel interference in multiuser wavelength-division multiplexing (WDM) is identified as the seemingly intractable factor limiting the achievable rate at high launch power. However, this distortion and similar ones arising from nonlinearity are primarily due to the use of methods suited for linear systems, namely WDM and linear pulse-train transmission, for the nonlinear optical channel. Exploiting the integrability of the nonlinear Schr\"odinger (NLS) equation, a nonlinear frequency-division multiplexing (NFDM) scheme is presented, which directly modulates non-interacting signal degrees-of-freedom under NLS propagation. The main distinction between this and previous methods is that NFDM is able to cope with the nonlinearity, and thus, as the the signal power or transmission distance is increased, the new method does not suffer from the deterministic cross-talk between signal components which has degraded the performance of previous approaches. In this paper, emphasis is placed on modulation of the discrete component of the nonlinear Fourier transform of the signal and some simple examples of achievable spectral efficiencies are provided.Comment: Updated version of IEEE Transactions on Information Theory, vol. 60, no. 7, pp. 4346--4369, July, 201

Red Spectral Tilt and Observable Gravity Waves in Shifted Hybrid Inflation

We consider supersymmetric shifted hybrid inflation models with a red tilted scalar spectral index n_s in agreement with the WMAP 7-yr central value. If non-minimal supergravity corrections are included, these models can also support a tensor-to-scalar ratio as large as r = 0.02, which may be observable by the Planck Satellite. In contrast to the standard supersymmetric hybrid inflation scenario, topological defects produced via gauge symmetry breaking are inflated away in the shifted version of the theory.Comment: 22 pages, 4 figures, and 1 tabl

Design and evaluation of a new pharmaceutical pictogram sequence to convey medicine usage

Pictorials may be used to augment textual instructions in the depiction of safety and warning information on medicines. The objective of this study was to design, develop and evaluate a simple and culturally appropriate pictogram sequence for using nystatin suspension, and to assess its understandability in low-literate Xhosa participants. A new pharmaceutical pictogram sequence was designed through focus group discussions and evaluated in a 2-phase process. The results of Phase 1 (30 participants) identified various problems associated with the new pictogram sequence. It was modified accordingly and re-evaluated in Phase 2 with 20 participants. All participants belonged to the Xhosa group, had between 0 and 7 years of formal schooling and had English as their second language. Acceptance of the new pictogram sequence was based on international standards (ANSI and ISO criterion) for evaluating the comprehensibility of pictograms. In Phase 1, the new pictogram sequence was correctly interpreted by 66.7% of the participants and this complied with the ISO criterion of 67% correct. In Phase 2, 95% of the participants were able to correctly interpret the new pictogram sequence. This result complied with the ANSI criterion of 85% correct, therefore, this new pictogram sequence was considered to be acceptable. This study has illustrated the success of using a consultative approach in the design of new pictograms

Expert Weighting Based Dynamic Eco-efficiency Assessment of World Consumption

Optimizing the consumption of natural resources and ensuring the availability of resources for both current and future generations has been the target for sustainability research. This paper aims to assess the eco-efficiency of global resource consumption through the environmental footprint perspective. The study effectively utilized EXIOBASE 3.41, a multi-region input-output (MRIO) database, for collecting data and Multi-criteria decision making (MCDM) approach for eco-efficiency assessment. Besides, the present paper utilizes expert weighting strategies such as EPP, SAB, Harvard, and EQUAL for assigning relative significance to various environmental indicators. Primarily, the data sample represents the influence of environmental stressors like GHG emission, land use, energy use, material consumption, water consumption. The study expands through three major scenarios in terms of importance to the economic and environmental outcomes. As such, with three scenarios and four weighting strategies, twelve situations are considered for the purpose of the study. The study findings indicate that the eco-efficiency score for given weighting strategies concerning economic and environmental impact demonstrates a significant statistical difference. The countries like China, India, Russia, Mexico, and Turkey are worst performing while Switzerland, Japan, UK, Germany, and France are best performing in terms of eco-efficiency score. Finally, k-mean clustering algorithm has applied to rank the countries centered on eco-efficiency score and weighing strategie

Influence of hyperhomocysteinemia on the cellular redox state - Impact on homocysteine-induced endothelial dysfunction

Hyperhomocysteinemia is an independent risk factor for the development of atherosclerosis. An increasing body of evidence has implicated oxidative stress as being contributory to homocysteines deleterious effects on the vasculature. Elevated levels of homocysteine may lead to increased generation of superoxide by a biochemical mechanism involving nitric oxide synthase, and, to a lesser extent, by an increase in the chemical oxidation of homocysteine and other aminothiols in the circulation. The resultant increase in superoxide levels is further amplified by homocysteinedependent alterations in the function of cellular antioxidant enzymes such as cellular glutathione peroxidase or extracellular superoxide dismutase. One direct clinical consequence of elevated vascular superoxide levels is the inactivation of the vasorelaxant messenger nitric oxide, leading to endothelial dysfunction. Scavenging of superoxide anion by either superoxide dismutase or 4,5-dihydroxybenzene 1,3-disulfonate (Tiron) reverses endothelial dysfunction in hyperhomocysteinemic animal models and in isolated aortic rings incubated with homocysteine. Similarly, homocysteineinduced endothelial dysfunction is also reversed by increasing the concentration of the endogenous antioxidant glutathione or overexpressing cellular glutathione peroxidase in animal models of mild hyperhomocysteinemia. Taken together, these findings strongly suggest that the adverse vascular effects of homocysteine are at least partly mediated by oxidative inactivation of nitric oxide