28 research outputs found
Empirical relations for the propagation characteristics of diffused channel waveguides
No full textEmpirical relations for the propagation constant and the field profile parameters of integrated optical diffused channel waveguides have been developed. The field profile used is the evanescent secant-hyperbolic field, which has been shown earlier to be a very good approximation for diffused channel-waveguide modes. Least-square fitting has been used to obtain the empirical relations. The results show that the error in empirical relations for the propagation constant is within 2% for a broad range of waveguide parameters. The obtained empirical relations for the field profile and the propagation constant have been used, as an example, to calculate the coupling length of diffused channel-waveguide-based directional couplers
Wavelet-Galerkin solver for the analysis of optical waveguides
No full textA new set of basis functions based on truncated Gaussian wavelets is proposed for optical waveguide analysis using the well-known Galerkin method. A spatially limited Gaussian wavelet train is formed by judiciously truncating the tails of Gaussian functions. The proposed set of basis functions produces a sparse eigenvalue equation when the wave equation is solved by the Galerkin method. The limited span of the basis functions makes the computation of integrals associated with matrix elements very fast with lower memory requirements. The effectiveness of the proposed basis functions is tested by comparing the results with those obtained by other methods and other basis functions for diffused and step index planar and channel waveguides. The results show a significant reduction in computation time while maintaining good accuracy
Improved optimal variational method to analyze optical rib waveguides
No full textWe present an improved optimal variational method (Vopt) to overcome the assumption of field separability in the two orthogonal directions. The improved Vopt method is shown to give accurate results with less computational effort. The method is applied to rib waveguides and the results are compared with those obtained using the computationally intensive finite-element method
Redox-Responsive Nanocapsules for the Spatiotemporal Release of Miltefosine in Lysosome: Protection against Leishmania
No full textLeishmaniasis, a vector-borne disease, is caused by intracellular parasite Leishmania donovani. Unlike most intracellular pathogens, Leishmania donovani are lodged in parasitophorous vacuoles and replicate within the phagolysosomes in macrophages. Effective vaccines against this disease are still under development, while the efficacy of the available drugs is being questioned owing to the toxicity for nonspecific distribution in human physiology and the reported drug-resistance developed by Leishmania donovani. Thus, a stimuli-responsive nanocarrier that allows specific localization and release of the drug in the lysosome has been highly sought after for addressing two crucial issues, lower drug toxicity and a higher drug efficacy. We report here a unique lysosome targeting polymeric nanocapsules, formed via inverse mini-emulsion technique, for stimuli-responsive release of the drug miltefosine in the lysosome of macrophage RAW 264.7 cell line. A benign polymeric backbone, with a disulfide bonding susceptible to an oxidative cleavage, is utilized for the organelle-specific release of miltefosine. Oxidative rupture of the disulfide bond is induced by intracellular glutathione (GSH) as an endogenous stimulus. Such a stimuli-responsive release of the drug miltefosine in the lysosome of macrophage RAW 264.7 cell line over a few hours helped in achieving an improved drug efficacy by 200 times as compared to pure miltefosine. Such a drug formulation could contribute to a new line of treatment for leishmaniasis.A. Das acknowledges SERB (India) Grants (CRG/2020/000492 and JCB/2017/000004) and DBT Grant (BT/PR22251/NNT/28/1274/2017) for supporting this research. N. Mukherjee acknowledges SERB (India) Grant PDF/2016/001437 and K. Das acknowledges the grant EMR/2015/001674 for supporting this research. Financial support from DST (DST/INSPIRE/03/2017/002477) is acknowledged by R.T. This manuscript bears CSMCRI registration no 7/2021.Pramanik, SK (corresponding author), CSIR Cent Salt & Marine Chem Res Inst, Bhavnagar 364002, Gujarat, India.
Mukherjee, N (corresponding author), CSIR Indian Inst Chem Biol, Canc Biol & Inflammatory Disorder Div, Kolkata 700032, India.
Chattopadhy, S (corresponding author), BITS Pilani, Pilani 403726, Goa, India.
Das, A (corresponding author), Indian Inst Sci Educ & Res Kolkata, Mohanpur 741246, W Bengal, India.
[email protected]; [email protected]; [email protected]
Process Model Accuracy Enhancement Using Cluster Based Approach
No full textFull chip resist simulation is a critical step in the lithography simulation of advanced CMOS technology nodes. The semi-empirical compact models (such as compact model 1, also known as CM1) are generally used in the semiconductor industries for resist simulation since the physical models are computationally expensive. The CM1 model considers physical effects of the resist process and uses a constant threshold on a two dimensional resist surface to extract the critical dimension (CD). However, the required threshold for different samples may vary over a range and therefore a constant threshold value may not hit an optimal solution for all the samples. In this paper, we propose a clustering based approach to enhance the accuracy of CM1 model and resist simulation. In this proposed approach, various attributes of the lithographic samples such as aerial image and pattern density are used to bin the samples into different groups (clusters). The CM1 model is then used to calibrate parameters individually for each group. This approach is verified by doing the resist simulation on one of the layers of 14nm CMOS technology and the results show good improvement in model accuracy
A Novel technique to measure propagation loss of optical waveguides
No full textA method to measure the propagation loss of optical waveguides is discussed. The measurement system involves two 3 dB couplers, a CCD camera and a signal processing unit. The propagation loss measured from this technique is found to be independent of coupling conditions. The propagation properties of waveguides prepared by proton exchange (PE) in Lithium Niobate and Silver ion exchange in BK7 glass substrates are examined. Finally the variation of mode propagation loss for various annealing parameters of PE waveguides is discussed
From Variations to Precision: Modeling and Optimization of Inner Spacer Etch in GAA FETs
No full textThis work introduces a robust machine learning framework for modeling and optimizing the inner spacer etch process in gate-all-around FET fabrication. Using an in-house Particle Monte-Carlo simulator, the etch process is modeled precisely across varied conditions. Gaussian Process Regression outperforms neural network models, achieving 98-99% accuracy in predicting etch front variations. Bayesian Optimization with adaptive sampling and successive domain reduction is utilized to fine-tune etch parameters, minimizing the error between predicted and target etch fronts. This integrated approach enables precise control over spacer-channel geometry, making this approach highly effective for advanced semiconductor manufacturing
Understanding Global Street Food Consumer Behavior and Experience: A Narrative Review of Literature and Development of Framework
No full textThis paper explores global street food consumer behavior and consumption experience. The aim of this paper is to gain a holistic comprehension of street food consumption decision making and experience through exploring nature and sources of perceptions, attitude and expectations surrounding street food, the characteristics of the product offering and the domain within which it is served and consumed. To achieve this aim the author engages in a narrative review of academic research on consumer behavior of street food, provides a holistic picture of consumption experience of street food through consolidating and interpreting research findings, and extends the theoretical understanding of street food consumption experience through development of a global consumer decision making framework. The review indicates that there is a growing interest in street food consumer behavior research. Studies have been done across many countries and published across a diverse set of multidisciplinary journals. Research findings from the selected articles collectively indicate that street food experience is multifaceted, includes cognitive and affective components, and happens at the meeting point of consumer psychology surrounding street food and the multi touch point dimensions of the experiencescape of street food. Tourists and domestic consumers seem to be cautiously enthusiastic about consuming street food, seeing benefits in an affordable, convenient, cultural, authentic, traditional and out of the routine experience but also risks about food safety. Consumers think vendors provide ample smell, taste, texture, appearance, flavor and fresh food at a value price and proficient service which is a big draw. At the same time, they have shown concerns about safe handling of food and desire several improvements in the areas of interaction, engagement and an enjoyable physical environment. Practical implications for street food businesses and street food destination tourism administrators are discussed and future research areas for academia recommended
On the characteristic polynomial of the Gross regulator matrix
No full textDasgupta S, Spieß M. ON THE CHARACTERISTIC POLYNOMIAL OF THE GROSS REGULATOR MATRIX. TRANSACTIONS OF THE AMERICAN MATHEMATICAL SOCIETY. 2019;372(2):803-827.We present a conjectural formula for the principal minors and the characteristic polynomial of Gross's regulator matrix associated to a totally odd character of a totally real field. The formula is given in terms of the Eisenstein cocycle, which was defined and studied earlier by the authors and collaborators. For the determinant of the regulator matrix, our conjecture follows from recent work of Kakde, Ventullo, and the first author. For the diagonal entries, our conjecture overlaps with the conjectural formula presented in our prior work. The intermediate cases are new and provide a refinement of the Gross-Stark conjecture
Addressing the Needs of F-2 Wives in the United States
No full textThe author analyzes the impact of current university regulations and policies on the everyday lives of wives of international students. The research process involved interviews with twenty-six women, located at two educational institutions, who came to the US on an F-2 visa (student dependent visa). It also included analysis of documents related to immigration policies and university regulations that had a direct impact on the experiences of wives of international students. The findings show that F-2 wives' adjustment experiences are strongly influenced by the level of institutional support provided by the university. The chapter concludes with recommendations for federal and university policies that create a welcoming environment for international students and their families.</jats:p
