Analysis of Image Processing Strategies Dedicated to Underwater Scenarios

Underwater images undergo quality degradation issues of an image, like blur image, poor contrast, non-uniform illumination etc. Therefore, to process these degraded images, image processing come into existence. In this paper, two important image processing methods namely Image restoration and Image enhancement are compared. This paper also discusses the quality measures parameters of image processing which will be helpful to see clear images

Robust and fragile PT-symmetric phases in a tight-binding chain

We study the phase-diagram of a parity and time-reversal (PT) symmetric tight-binding chain with $N$ sites and hopping energy $J$, in the presence of two impurities with imaginary potentials $\pm i\gamma$ located at arbitrary (P-symmetric) positions $(m, \bar{m}=N+1-m)$ on the chain where $m\leq N/2$. We find that except in the two special cases where impurities are either the farthest or the closest, the PT-symmetric region - defined as the region in which all energy eigenvalues are real - is algebraically fragile. We analytically and numerically obtain the critical impurity potential $\gamma_{PT}$ and show that $\gamma_{PT}\propto 1/N\rightarrow 0$ as $N\rightarrow\infty$ except in the two special cases. When the PT symmetry is spontaneously broken, we find that the maximum number of complex eigenvalues is given by $2m$. When the two impurities are the closest, we show that the critical impurity strength $\gamma_{PT}$ in the limit $N\rightarrow\infty$ approaches $J$ ($J/2$) provided that $N$ is even (odd). For an even $N$ the PT symmetry is maximally broken whereas for an odd $N$, it is sequentially broken. Our results show that the phase-diagram of a PT-symmetric tight-binding chain is extremely rich and that, in the continuum limit, this model may give rise to new PT-symmetric Hamiltonians.Comment: 10 pages, 4 figure

Fragile aspects of topological transition in lossy and parity-time symmetric quantum walks

Quantum walks often provide telling insights about the structure of the system on which they are performed. In PT-symmetric and lossy dimer lattices, the topological properties of the band structure manifest themselves in the quantization of the mean displacement of such a walker. We investigate the fragile aspects of a topological transition in these two dimer models. We find that the transition is sensitive to the initial state of the walker on the Bloch sphere, and the resultant mean displacement has a robust topological component and a quasiclassical component. In PT symmetric dimer lattices, we also show that the transition is smeared by nonlinear effects that become important in the PT-symmetry broken region. By carrying out consistency checks via analytical calculations, tight-binding results, and beam-propagation-method simulations, we show that our predictions are easily testable in today’s experimental systems

Parity-time symmetric systems with memory

Classical open systems with balanced gain and loss, i.e. parity-time ($\mathcal{PT}$) symmetric systems, have attracted tremendous attention over the past decade. Their exotic properties arise from exceptional point (EP) degeneracies of non-Hermitian Hamiltonians that govern their dynamics. In recent years, increasingly sophisticated models of $\mathcal{PT}$-symmetric systems with time-periodic (Floquet) driving, time-periodic gain and loss, and time-delayed coupling have been investigated, and such systems have been realized across numerous platforms comprising optics, acoustics, mechanical oscillators, optomechanics, and electrical circuits. Here, we introduce a $\mathcal{PT}$-symmetric (balanced gain and loss) system with memory, and investigate its dynamics analytically and numerically. Our model consists of two coupled $LC$ oscillators with positive and negative resistance, respectively. We introduce memory by replacing either the resistor with a memristor, or the coupling inductor with a meminductor, and investigate the circuit energy dynamics as characterized by $\mathcal{PT}$-symmetric or $\mathcal{PT}$-symmetry broken phases. Due to the resulting nonlinearity, we find that energy dynamics depend on the sign and strength of initial voltages and currents, as well as the distribution of initial circuit energy across its different components. Surprisingly, at strong inputs, the system exhibits self-organized Floquet dynamics, including $\mathcal{PT}$-symmetry broken phase at vanishingly small dissipation strength. Our results indicate that $\mathcal{PT}$-symmetric systems with memory show a rich landscape

EFFECT OF FORMALIN VAPOURS ON PULMONARY FUNCTIONS OF MEDICAL STUDENTS IN ANATOMY DISSECTION HALL OVER A PERIOD OF ONE YEAR

Abstract : Formalin is extensively used for preservation of cadavers in department of Anatomy. However it is a noxious chemical which vaporises at normal room temperature in the air and may cause respiratory health problems among first year medical students. The study was planned to observe the effect of formalin vapours on lung function tests of first year medical students who are exposed routinely for 2 hrs every day for 6 days per week throughout the year. Following written informed consent clinically healthy 100 medical students between age group 18-23 yrs were subjected to pulmonary function testing by computerised spirometery. The dynamic lung function tests (FVC, FEV1, FEV1%, , PEFR) were measured on four occasions-basal (before exposure), 1 month, 6 months, 11 months of exposure to formalin vapours in anatomy dissection hall. The study revealed statistically significant (P<0.0001) decreases in FVC, FEV1%, FEF , PEFR except FEV1 after 1 month of exposure to anatomy dissection hall. The decrease in all the parameters slowly reverted back towards normal basal values across 6 and 11 months and was statistically significant in all (P<0.0001) except FVC. Acute exposure to formalin vapours at anatomy dissection hall decreases the respiratory functions, however on long term exposure the body corrects the damage. Further studies are required to see the changes at cellular levels and the extent of damage to respiratory system. Key words : formalin pulmonary functions anatomy dissection hall Indian J Physiol Pharmacol 2013; 57(3) : 255-26

COVID-19 Vaccination status among Health care workers diagnosed with COVID-19 in a tertiary care institute of Uttarakhand: A Cross-sectional Study

Background: Vaccines are considered as the one of the main pillars in halting and ending the presently on-going coronavirus disease (COVID-19 disease) pandemic which has spread globally since it was first detected in Wuhan, China in December 2019. In the absence of specific therapy, infection prevention practices and mass vaccination remains the mainstay in controlling the disease. Objectives: Objective of the study was to assess COVID-19 vaccination status, socio-demographic and clinical profile among healthcare workers diagnosed with COVID-19. Methodology: A cross-sectional survey from 1st March 2021 to 30th June 2021 among healthcare workers who were diagnosed with COVID-19 in a tertiary care institute of Uttarakhand, India was conducted, and universal sampling was used. Institutional Ethics Committee approved this study. Results: Total 662 healthcare workers were diagnosed with COVID-19. 429 (64.8%) of these COVID-19 diagnosed healthcare workers had received either single (129,30%) or both dose (300,70%) of COVID-19 vaccine while remaining 233 (35.2%) belonged to non-vaccinated group. History of exposure to COVID-19 positive patients was higher in vaccinated (66.4%) than in non-vaccinated group (55%) (p = 0.004). Hospitalisation was found to be higher among non-vaccinated (5.6%) than vaccinated group (2.3%) (p = 0.029). Conclusions: This study concludes that being vaccinated against COVID-19 disease provides protection against severe infection and reduces the need for hospitalization