Birefringence analysis of multilayer leaky cladding optical fibre

We analyse a multilayer leaky cladding (MLC) fibre using the finite element method and study the effect of the MLC on the bending loss and birefringence of two types of structures: (i) a circular core large-mode-area structure and (ii) an elliptical-small-core structure. In a large-mode-area structure, we verify that the multilayer leaky cladding strongly discriminates against higher order modes to achieve single-mode operation, the fibre shows negligible birefringence, and the bending loss of the fibre is low for bending radii larger than 10 cm. In the elliptical-small-core structure we show that the MLC reduces the birefringence of the fibre. This prevents the structure from becoming birefringent in case of any departures from circular geometry. The study should be useful in the designs of MLC fibres for various applications including high power amplifiers, gain flattening of fibre amplifiers and dispersion compensation.Comment: 18 page

Co-axial dual-core resonant leaky fibre for optical amplifiers

We present a co-axial dual-core resonant leaky optical fibre design, in which the outer core is made highly leaky. A suitable choice of parameters can enable us to resonantly couple power from the inner core to the outer core. In a large-core fibre, such a resonant coupling can considerably increase the differential leakage loss between the fundamental and the higher order modes and can result in effective single-mode operation. In a small-core single-mode fibre, such a coupling can lead to sharp increase in the wavelength dependent leakage loss near the resonant wavelength and can be utilized for the suppression of amplified spontaneous emission and thereby gain equalization of an optical amplifier. We study the propagation characteristics of the fibre using the transfer matrix method and present an example of each, the large-mode-area design for high power amplifiers and the wavelength tunable leakage loss design for inherent gain equalization of optical amplifiers.Comment: 6 page

URBAN SPRAWL ANALYSIS USING SHANNON’S ENTROPY AND FRACTAL ANALYSIS: A CASE STUDY ON TIRUCHIRAPPALLI CITY, INDIA

Urban sprawl places a major role in urban growth management all over the world. Urban growth of the city is analysed for the effective planning and improving the socio-economic conditions for decision making and the development of the city. In this study, the urban sprawl of Tiruchirappalli city is analysed from 2006 to 2017 using data of Indian remote sensing satellites, Resourcesat-1 and Resourcesat-2 with multi spectral band (red, green and near-infrared). The temporal change for four-time periods is calculated using object based image analysis temporal inversion approach. From 2006 to 2017 there is an increase in total urban area from 58 km2 to 90 km2, resulting of 33% increment in 11 years. Shannon entropy is calculated for four-time periods and it shows that after 8 km from Central Business District (CBD), Shannon entropy is increasing and dispersion is high. The influence of roads on urban sprawl is calculated using buffer function analysis and the highest contribution among all the highways is by NH-67 and NH-210.The fractal analysis of the urban area for four-time period is performed and fractal dimension is calculated. Fractal dimension helps in measuring the space filling extent and urban growth complexity and is used to characterise the compactness of urban pattern and regularities of urban boundaries.The fractal dimension of Tiruchirappalli increases from 1.584 in 2006 to 1.639 in 2017

Reliability Analysis of The Estimated Parameters in Groundwater Systems

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

New insights into molecular links between microbiota and gastrointestinal cancers:A literature review

Despite decades of exhaustive research on cancer, questions about cancer initiation, development, recurrence, and metastasis have still not been completely answered. One of the reasons is the plethora of factors acting simultaneously in a tumour microenvironment, of which not all have garnered attention. One such factor that has long remained understudied and has only recently received due attention is the host microbiota. Our sheer-sized microbiota exists in a state of symbiosis with the body and exerts significant impact on our body’s physiology, ranging from immune-system development and regulation to neurological and cognitive development. The presence of our microbiota is integral to our development, but a change in its composition (microbiota dysbiosis) can often lead to adverse effects, increasing the propensity of serious diseases like cancers. In the present review, we discuss environmental and genetic factors that cause changes in microbiota composition, disposing of the host towards cancer, and the molecular mechanisms (such as β-catenin signalling) and biochemical pathways (like the generation of oncogenic metabolites like N-nitrosamines and hydrogen sulphide) that the microbiota uses to initiate or accelerate cancers, with emphasis on gastrointestinal cancers. Moreover, we discuss how microbiota can adversely influence the success of colorectal-cancer chemotherapy, and its role in tumour metastasis. We also attempted to resolve conflicting results obtained for the butyrate effect on tumour suppression in the colon, often referred to as the ‘butyrate paradox’. In addition, we suggest the development of microbiota-based biomarkers for early cancer diagnosis, and a few target molecules of which the inhibition can increase the overall chances of cancer cure