54 research outputs found
Theorizing or Negotiating the Law?: A Response to Devika Hovell
No full textDevika Hovell’s article is a very welcome and useful contribution to the debate regarding the “accountability” (whatever the term may mean) of international organizations, and the United Nations in particular. The author argues that scholarship has tended to focus on (descriptive) state practice to the detriment of (normative) theoretical appeal, and so the relevant discussion “has received inadequate theoretical attention.” In response, she sets out to tell the story of the United Nations being held to account through a highly theorized (and, if I may venture even at the outset, perhaps a bit stylized) scheme of contrasting “instrumentalist,” “dignitarian,” and “public interest” approaches to due process. This she applies to two case studies, one regarding targeted sanctions imposed by the UN Security Council, mainly in the context of antiterrorism; and one regarding the cholera outbreak in Haiti, where the United Nations has been implicated. Hovell critiques both the instrumentalist and dignitarian approaches, which correspond in broad terms to legal action at the international, and the domestic/regional level, respectively, and argues in favor of a “public interest” approach as better reflecting a “value-based” due process.</jats:p
Effect of egg yolk extract on proliferation and myogenic differentiation of C2C12 myoblasts
No full textMuscle wasting disorders like atrophy and sarcopenia are characterized by compromised skeletal muscle mass and function. One of the many causes of muscle wasting reported is the failure of satellite cells to fuse and form myofibres. Satellite cells are an integral part of skeletal muscle regeneration because of their self-renewal and differentiation abilities. Muscle regeneration research with respect to satellite cells has stimulated interest in discovering factors that enhance proliferation and differentiation as a first step in the regenerative process. The importance of nutrition in regulating muscle mass and muscle protein synthesis is well established. However, limited literature is available regarding the role of nutrition in muscle regeneration; specifically with respect to satellite cells. As for nutrition, chicken egg yolk appears to be a promising candidate. Egg yolks are rich in nutrients such as vitamins, minerals, amino acids and proteins which can provide sustained supply of nutrition to the cells in-vitro. In the present study, we tested the effect of different fractions and concentrations of egg yolk extract on C2C12 myoblasts. For this purpose, egg yolk extract was supplemented in growth media and cells were grown in this nutrient rich media for one week. Cell viability, fluorescence imaging and mRNA expression of muscle specific genes were analyzed at specific time points of proliferation and differentiation stages of myoblast. The study results showed that supplementation of the egg yolk extract in media enhanced proliferation and differentiation of myoblasts in a dose dependent manner which was analyzed by increase in cell viability, number of nuclei, number of myofibres and mRNA expression of muscle specific genes such as MyoD and myogenin.M.S.Includes bibliographical referencesby Devika Umesh Jogleka
We Listen Together
No full textIn this brief essay, the author responds to a performative panel of essays by students of Devika Chawla. He situates his reading of the event betwixt and between typical modes of performance studies research, demonstrating how the panelists reveal narrative's power to reflect on the layering of time, power and privilege, and ways of knowing.</jats:p
Modulated surface texturing on temporary aluminium substrate for flexible thin-film solar cells
No full textThin-film photovoltaic technologies are gaining momentum over the currently dominated crystalline silicon technologies. In addition to the competitive prices, flexible thin-film technology especially has the added advantage such as in building integrated photovoltaics (BIPV) due to its flexibility and light weight. HyET Solar B.V. is a company based in the Netherlands which state-of-the-art Roll to Roll (R2R) technology to produce such flexible solar cells. A temporary aluminum foil is used as substrate on to which FTO/p-i-n solar cell stack is deposited. The temporary foil is etched away, and the layers are encapsulated in low cost polymer foils. This thesis is part of the on-going FlamingoPV (Flexible Lightweight Advanced Materials In Next Generation of PV) project in collaboration between HyET Solar and TU Delft, to develop single, tandem and triple junction cells with 12, 13 and 14% efficiencies and a lifetime longer than 35 years. This thesis is inspired by the work of Tan et. al [8] where record efficiency cells were achieved on solar cells deposited on ‘Modulated Surface Textured’ (MST) glass substrates. In MST, increased light scattering is obtained by superposition of various scattering mechanisms which is achieved by introducing different textures at different interfaces and stacking them together. The requirements of the MST are two-fold: to provide efficient light trapping and to aid in the growth of high-quality layers. The aim is to introduce MST in the R2R process by developing micro sized crater-shaped features on the temporary Al foil on to which naturally nano sized V-shaped textures of FTO is deposited. The crater-shaped features are developed on the Al foil (~110 um) using wet chemical etching techniques. Various acid and alkaline based etchants are experimented. The etching parameters- concentration and temperature of the etchant and the etching time are varied to achieve the optimum recipe. These parameters should be varied such that the features have a correlation length (an estimate of how wide the feature is) 3-4 um and an aspect ratio (ratio of RMS roughness to correlation length) of 12-14%. These features are characterized using SEM and AFM to measure the aforesaid parameters and reflectance and angular intensity distribution measurements to measure its effectiveness of scattering. Alkaline based etchants (KOH and NaOH) resulted in crater-shaped features unlike acid etchants which resulted in pyramidal features. It was observed that there is an initial ‘induction period’ before which the etching started. For lower temperature, time and concentration, the induction period is longer. To ensure mechanical stability during deposition stages, the foil needs to be thicker than 70 um on lab-scale. The above-mentioned etching parameters were varied, and the best recipe was found to be 1.78M KOH at 70°C for an etching time of 2 minutes, 1.78M KOH at 60°C for 3 minutes and 1.42M NaOH at 70°C for 2.5 minutes. These samples displayed a correlation length 4-4.6 um and aspect ratios from 12-14% which is close to the targeted values and are higher than the existing texturing at HyET (‘factory baseline’) which had correlation length and aspect ratios of 500 nm and 5.7% respectively. These samples also showed higher scattering compared to the factory baseline. The nc-Si:H and a-Si:H/nc-Si:H layers deposited on to these samples resulted in dense high-quality layers. The TCO/p-i-n layers deposited also adapted the texturing pattern of the Al foil, unlike the factory baseline where the Al surface morphology was not adapted by the other layers as the features were significantly smaller. Further, to enhance the uniformity of texturing, various ‘chelating agents’ and ‘surfactants’ such as gluconic acids and glycols as well as varying the speed of etching to ensure homogenous contact of etchant with the foil was carried out. Both these techniques resulted in in an increased etch rate as well as an increase in the density of the craters on the foil. Considering the limitations of the R2R process, the best lab recipes were adapted (50°C, 1.42M NaOH, 1.8 minutes) to implement on the R2R etching machine. The resulting Al foil had higher surface morphology parameters and scattering compared to the factory baseline. The cells deposited on this texturing adapted the morphology of the Al foil. Optical simulations were done using GenPro4 where the AFM data of the textures were given as the input. The best lab samples as well as the R2R testing recipe showed larger absorption in the higher wavelengths in both nc-Si:H single junction and a-Si:H/nc-Si:H tandem cells, compared to the standard factory baseline texturing.Flamingo PVElectrical Engineering | Electrical Power Engineerin
Modelling of Relaxation Phenomena in Transformer Oil-Paper-Pressboard Insulation to determine the Dielectric Response Behaviour under DC and Impulse voltages
No full textThe factory acceptance tests are extremely important for the deployment and service life of Extra-high voltage transformers (EHV) and reactors. An essential part of such tests is Lightning Impulse (LI) tests which are intended to ensure that the transformer insulation withstands the transient lightning overvoltages which may occur while in service. These tests are usually done with negative polarity to prevent air side flashovers. In recent years, there has been an increasing demand for additional positive polarity lightning impulse tests to secure the reliability and life of the transformers. The transformer, during its service life, is subjected to massive electrical stresses due to lightning strikes and switching impulses. As a consequence, this may lead to the degradation of the transformer insulation. During lightning impulse tests, ionisations might occur in the pressboard/insulating liquid insulation system, which would lead to the development of space charges. The space charges generated may have an influence on the withstand behaviour of the insulation corresponding to applied impulse voltage. There is also a possibility of field enhancements due to the effect of space charge, especially when tested consecutively with opposite polarity. During the acceptance tests on transformers at SGB-SMIT transformers, a waiting period of one hour is given between the negative polarity LI and positive polarity LI. This arbitrary waiting time is given under the assumption that this will allow any ’trapped’ charges to decay and provide relaxation time for the slower polarisation processes. So the main question is whether this waiting period allows sufficient time for the decay of charges in the transformer insulation. For this analysis, the relaxation time characteristics of the transformer insulation system were investigated by estimation of the time dependency of depolarisation currents in the oil, paper/pressboard insulation. In this thesis, the characteristic of the time-domain dielectric response and the time dependency of the currents due to depolarisation of charges under DC and impulse voltage was investigated by the polarisation-depolarisation current (PDC) measurements on the test samples. The PDC method is a non-destructive diagnostic method for evaluating transformer insulation in the time domain. A test set up was built to represent a simplified model of transformer insulation comprising of mineral oil, paper and pressboard. The measurements of discharge voltage over time were conducted on the test samples of oil, paper and pressboard to understand the time-dependency of polarisation-depolarisation processes occurring within the transformer insulation. Two dominant time constants of decay were estimated for oil, paper and pressboard samples. The results from the discharge voltage measurement were compared with the analytical solution of the output voltage of the equivalent R-C circuit of the test sample which revealed that there were more than two polarisation phenomena occurring within the composite test sample of oil, paper and pressboard. Later, to mitigate the inconsistencies with the simplified R-C model, it was extended and modified based on the linear dielectric response theory to study the dielectric response behaviour of transformer insulation under DC voltage for longer charging times (tc=10,000 seconds). The modified R-C model was envisioned and developed in PSPICE simulation environment. The model incorporates the effect of the individual polarisation processes occurring within the constituent dielectrics of transformer oil-paper-pressboard insulation. The dielectric properties like conductivity and dielectric response function f (t ) can be estimated reasonably accurately with this modified R-C model. A comparison of the maximum and minimum values of the polarisation currents of the composite test sample obtained from the simulated model and from dielectric testing was conducted. The results demonstrated that relative errors were limited to a maximum of 8 %. The time-domain polarisation and depolarisation behaviour of composite transformer insulation was analysed under DC and impulse voltages from simulations of PDC measurements using PSPICE simulation software. It was observed that for the same thickness of solid insulation, as the oil-gap increases, the magnitude of the depolarisation current at the end of the discharging period (10,000 seconds) also increases. For identical oil-gaps, as the thickness of the pressboard in the composite test sample of oil-paper-pressboard was increased, the depolarisation currents show a delayed response to decay to a minimum value at the end of discharging duration. The time dependency of depolarisation currents at the end of discharging time of one hour was realised for impulse voltages. The study of the depolarisation currents under the influence of impulse voltage revealed that the charge induced field at the end of the discharging period of one hour does not exceed the permissible threshold electric field of 2 kV/mm inside the transformer insulation. In the future, the model could be developed into a valuable diagnostic tool for studying the dielectric responses of complex transformer insulation under the influence of different parameters like moisture content, ageing products, geometrical configuration and temperature
Optimisation of Interior Permanent Magnet Generator in Propeller Type Tidal Turbines
No full textOver the past few decades, there has been a steep increase in efforts to generate electricity from clean and renewable energy sources so as to reduce consumption of fossil fuels. A considerable amount of research is in progress to explore the scope of various sustainable power sources; among which tidal energy is estimated to have a huge potential. With advancements in technology, it is predicted that electricity from tidal energy would increase in the coming years. It is necessary to have highly efficient generators that can convert tidal energy to electricity. Propeller type generation system using Permanent Magnet Synchronous Machines (PMSMs) are found to be suitable for the application of tidal generators. For the best utilisation of resources, it is essential to improve the performance of these machines in several aspects. And hence, multi-objective optimisation of electrical machines is emerging to be of high significance. The key goal of this thesis is to design, model and optimise a PMSM generator so as to get the desired power while considering other design objectives, including the efficiency, total volume of the machine and weight of magnets. The thesis is divided into two parts. The first part consists of design, modelling and analysis of the PMSM machine. Initially, all the required machine constraints are identified and a topology is selected. An analytical model is built after which the machine is modelled using the Finite Element Method (FEM). The model is analysed where various key characteristics of the machine such as flux linkages, induced EMF, inductance and torque are calculated. This is validated by ensuring that results from FEM model and analytical model match. In order to optimize the machine; certain geometric parameters are varied to locate the dominant geometrical parameters. The second part of the machine consists of optimisation. A multi-objective Genetic Algorithm (GA) optimization is carried out to generate data to search for an optimal design. The three objectives for optimisation are higher efficiency, lower total volume and lesser weight of magnets. The analytical model is used in the optimisation algorithm. Since this is a multi-objective optimisation, a set of solutions (Pareto set) is generated from which a single solution is chosen. This selected solution is applied to the FEM model and thus finally an optimized model of the machine is developed. An analysis is carried out on the optimised model. Finally, the optimised model and the initial model are compared and the results are explained.Master Thesis -M Sc. Electrical Power Engineering (Power Electronics and Electrical Machines)Electrical Engineering | Electrical Power Engineerin
Hindu Arranged Marriage within the Indian American Community
No full text67 p.As families started to migrate out of India they brought the custom of arranged marriage with them to the United States. The author focuses on how Hindus in America are adjusting to the far-flung geography of Hindu communities, the role of caste and dowry, and technology. In addition to a literature review, the author also interviewed a group of mothers and second generation men and women between the age of 15 and 30
Gold nanoprobes for theranostics
Full text linkGold nanoprobes have become attractive diagnostic and therapeutic agents in medicine and life sciences research owing to their reproducible synthesis with atomic level precision, unique physical and chemical properties, versatility of their morphologies, flexibility in functionalization, ease of targeting, efficiency in drug delivery and opportunities for multimodal therapy. This review highlights some of the recent advances and the potential for gold nanoprobes in theranostics
Studies on Micro Algal Flora in Fresh Water Bodies in Mysore
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
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