A Robust Continuous Time Fixed Lag Smoother for Nonlinear Uncertain Systems

This paper presents a robust fixed lag smoother for a class of nonlinear uncertain systems. A unified scheme, which combines a nonlinear robust estimator with a stable fixed lag smoother, is presented to improve the error covariance of the estimation. The robust fixed lag smoother is based on the use of Integral Quadratic Constraints and minimax LQG control. The state estimator uses a copy of the system nonlinearity in the estimator and combines an approximate model of the delayed states to produce a smoothed signal. In order to see the effectiveness of the method, it is applied to a quantum optical phase estimation problem. Results show significant improvement in the error covariance of the estimator using fixed lag smoother in the presence of nonlinear uncertainty.Comment: 8 pages, will be presented in 52nd Conference on Decision and Contro

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

Hawking radiation of scalar particles from accelerating and rotating black holes

Hawking radiation of uncharged and charged scalars from accelerating and rotating black holes is studied. We calculate the tunneling probabilities of these particles from the rotation and acceleration horizons of these black holes. Using the tunneling method we recover the correct Hawking temperature as well

Minimal Supersymmetric Hybrid Inflation, Flipped SU(5) and Proton Decay

Minimal supersymmetric hybrid inflation utilizes a canonical Kahler potential and a renormalizable superpotential which is uniquely determined by imposing a U(1) R-symmetry. In computing the scalar spectral index $n_s$ we take into account modifications of the tree level potential caused by radiative and supergravity corrections, as well as contributions from the soft supersymmetry breaking terms with a negative soft mass-squared term allowed for the inflaton. All of these contributions play a role in realizing $n_s$ values in the range 0.96-0.97 preferred by WMAP. The U(1) R-symmetry plays an important role in flipped SU(5) by eliminating the troublesome dimension five proton decay. The proton decays into $e^+ \pi^0$ via dimension six operators arising from the exchange of superheavy gauge bosons with a lifetime of order $10^{34}$-$10^{36}$ years.Comment: 14 pages, 8 figure

Observable Gravity Waves From Supersymmetric Hybrid Inflation

We identify models of supersymmetric hybrid inflation in which the tensor-to-scalar ratio, a canonical measure of gravity waves produced during inflation, can be as large as 0.03 or so, which will be tested by the Planck satellite experiment. The scalar spectral index lies within the WMAP one sigma bounds, while $|d n_s / d\ln k| \lesssim 0.01$.Comment: (v1) 19 pages, 1 table, 3 figures. (v2) 20 pages; updated figures, included additional discussion, footnotes, and referenc

Social media usage in academic research

Recently researchers have used “conversation prism” and “social media prisma”, to consolidate social medias with respect to their use. Although both identified 25 types, having average five examples each, they did not identify contribution of each type in academic research. Moreover some of mentioned social services had been suspended or changed. In this paper we attempt to access each social media mentioned in conversation prism in order to first, identify services that are operational to date, services which have suspended and those which have changed during course of time. Second, we compare number of publications associated with each social media, in order to identify which social media has contributed most to academic research. Third, we attempt to find correlation between number of publications and development tools provided by respective social applications. Fourth, social medias are ranked with respect to number of times other social medias share content with respective social application. It was found that out of 168 social applications, 10% changed their service objective while 13% were suspended. Among all social application, AMAZON had highest i.e. 147,000 number of citations on Google scholar whereas 90.7% of total citations were contributed by top 30 social medias. For developers, 22 out of top 30 social medias provided developer options in form of either application programming interface (API) or software development kits (SDK) and Facebook was found to be most cross referred social media based on content sharing. Finally conclusion and future work of study is presented