234 research outputs found
First person – Varun Jayeshkumar Shah
No full textABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Varun Jayeshkumar Shah is the first author on ‘CRL7SMU1 E3 ligase complex-driven H2B ubiquitination functions in sister chromatid cohesion by regulating SMC1 expression’, published in Journal of Cell Science. Varun is a PhD student in the lab of Dr Subbareddy Maddika at the Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India, investigating the role of LisH-domain-containing proteins in the assembly of multi-subunit E3 ligase complexes.</jats:p
Aggressive Risk factor REduction STudy for Atrial Fibrillation (ARREST-AF) implications for ablation outcomes: A Randomized Clinical Trial
No full text2024 AHA Late-Breaking Science Abstracts - 4171701Rajeev Pathak, Adrian Elliott, Dennis Lau, Melissa Middeldorp, Dominik Linz, John Fitzgerald, Jonathan Ariyaratnam, Varun Malik, Jean Jacques Noubiap, Rajiv Mahajan, Walter Abhayaratna, Jonathan Kalman, Prashanthan Sander
Social rights and economics : claims to health care and education in developing countries
No full textThe author analyzes contemporary rights-based and economic approaches to health care and education in developing countries. He assesses the foundations and uses of social rights in development, outlines an economic approach to improving health and education services, and then highlights the differences, similarities, and the hard questions that the economic critique poses for rights. The author argues that the policy consequences of rights overlap considerably with a modern economic approach. Both the rights-based and the economic approaches are skeptical that electoral politics and de facto market rules provide sufficient accountability for the effective and equitable provision of health and education services, and that further intrasectoral reforms in governance, particularly those that strengthen the hand of service recipients, are needed. There remain differences between the two approaches. Whether procedures for service delivery are ends in themselves, the degree of disaggregation at which outcomes should be assessed, the consequences of long-term deprivation, metrics used for making tradeoffs, and the behavioral distortions that result from subsidies are all areas where the approaches diverge. Even here, however, the differences are not irreconcilable, and advocates of the approaches need not regard each other as antagonists.Health Monitoring&Evaluation,Health Systems Development&Reform,Decentralization,Public Health Promotion,Early Child and Children's Health,Health Monitoring&Evaluation,Health Economics&Finance,Poverty Assessment,Agricultural Knowledge&Information Systems,Gender and Education
Coherency matrices for characterization of vector optical fields
No full textWe describe optical coherency matrices as a generalized method for characterizing the statistical properties of optical fields. We then use this formalism to classify optical fields, in terms of separability, and transfer of entropy between multiple degrees of freedom.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-12-01The student, Varun Ajit Kelkar, accepted the attached license on 2019-07-12 at 20:22.The student, Varun Ajit Kelkar, submitted this Thesis for approval on 2019-07-12 at 20:30.This Thesis was approved for publication on 2019-07-15 at 11:29.DSpace SAF Submission Ingestion Package generated from Vireo submission #14293 on 2020-02-28 at 17:34:54Made available in DSpace on 2020-03-02T22:28:39Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-07-15Embargo set by: Seth Robbins for item 113953
Lift date: 2022-03-02T22:28:46Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 113953
Lift date: 2022-03-02T22:38:05Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 113953
Lift date: 2022-03-02T22:39:04Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 113953 on 2022-03-03T10:15:30Z
Determination of structural changes and phase transformations in boron carbide by static and dynamic studies
No full textRecent transmission electron microscopy results demonstrate that the failure of B4C is commensurate with the segregation of boron icosahedra embedded in amorphous carbon in 2–3 nm wide amorphous bands along the (113) lattice direction, in good agreement with our recent theoretical results. Boron carbide is generally composed of multiple polytypes of B4C which have the same primitive lattice parameters but differ from each other by the location of the boron and carbon atoms in the unit cells. The unit cells are formed by a 12-atom B12-nCn icosahedron and a 3-atom (C3-nBn) chain. Our theoretical results indicate that one polytype, B12(C3), whose formation is responsible for
the failure of the entire material. This anomalous and poorly understood glass-like behavior in boron carbide has been the subject of research since its discovery over 70 years ago. The characterization of disorder in hot pressed and powder boron carbide samples
is therefore of primary interest. The research work has focused on characterization techniques which can be used at a micrometric sampling size so that individual powder grains of the material can be utilized. Specifically, micro-Raman and electrical
conductivity measurements can be used with micrometric gap cells to understand the disorder in B4C.The results also demonstrate that it is possible to induce transformations in boron carbide using electric fields that are comparable with those obtained under shock and nanoindentation. Our calculations present a hypothesis which can provide a solution to prevent the
premature failure of B4C. A route to achieve suppression of the B12(CCC) polytype without significantly affecting the elastic constants is via low concentration Silicon (Si) doping of B4C. Suppression of B12(CCC) by Si doping has implications towards
development of boron carbide armor with improved properties for protection against high velocity threats. In order to achieve this, nanostructures (nanowires, nanorods, etc.) of Sidoped boron carbide have been synthesized using a Solid-Liquid-Solid (SLS) growth
mechanism. The resulting structures have been characterized by SEM, TEM and Raman
spectroscopy and consolidated to evaluate their mechanical properties. In addition, the application of nanowires in a transparent and thermally conducting nanocomposite is demonstrated.Ph.D.Includes abstractVitaIncludes bibliographical referencesby Varun Gupt
The Need for Continued Innovation in Solar, Wind, and Energy Storage
No full textVarun Sivaram is the Philip D. Reed fellow for science and technology at the Council on Foreign Relations. He is also an adjunct professor at Georgetown University, an adjunct senior research scholar at Columbia University, and a member of the energy and environment advisory boards at Stanford University. He is the author of the book, Taming the Sun: Innovations to Harness Solar Energy and Power the Planet (MIT University Press, 2018) and the editor of the book, Digital Decarbonization: Promoting Clean Energy Systems Through Digital Innovations (CFR Press, 2018). Forbes named him one of its 30 under 30 in law and policy, and Grist named him one of the top 50 leaders in sustainability
Heavy Oil and Bitumen Recovery by Hot Solvent Injection: An Experimental and Computational Investigation
No full textAbstract
Thermal and miscible methods are commonly used for in-situ recovery of heavy oil and bitumen. Both techniques have their own limitations and associated shortcomings, often times yielding an inefficient process. The most common thermal method is steam injection, which is highly energy intensive. Steam generation costs and water production affect the economics of the thermal technique adversely. On the other hand, miscible methods are energy effective but their economics depends on the solvent retrieval. Various combinations of these two techniques such as co- or alternate injection of steam and solvent have been proposed as a solution, but no optimum method has yet been developed.
Thermal and miscible methods can be combined by co-injecting solvent with steam or injecting solvent into a pre-heated reservoir. Current work was undertaken to study the performance of solvents at higher temperatures for heavy oil/bitumen recovery. Glass bead packs and Berea sandstone cores were used in the experiments to represent different types of pore structures, porosity and permeability. After saturating with heavy oil, the samples were exposed to the vapor of paraffinic solvents (propane and butane) at a temperature above the boiling point of the solvent, and a constant pressure of 1500 kPa. A mechanical convection oven was used to maintain constant temperature across the setup. The setup was designed in such a way that a reasonably long sample (up to 30 cm) can be tested to analyze the gravity effect. The oil recovered from each of these experiments was collected using a specifically designed collection system and analyzed for composition, viscosity and asphaltene content.
The amount of oil recovered in each case was also analyzed and the quantity and nature of asphaltene precipitated with each of the tested solvents under the prevailing temperature and pressure of the experiment was reported. It was observed that recovery decreased with increasing temperature and pressure of the system for both the solvents, and that the best results were found when experimental temperature is only slightly higher than the saturation temperature. It was also noticed that butane diluted the oil more than propane which resulted in lower asphaltene content and viscosity of oil produced with butane as a solvent.
To understand the mechanics of the process and to explain the observations of these experiments, additional experiments were done on tighter samples of different sizes, along with numerical simulation and visualization experiments. The effects of temperature and pressure on the recovery were studied using a commercial reservoir simulator. Propane, butane and pentane were used as solvents. Asphaltene precipitation was also modeled.
To investigate the phenomenon further, 2-D glass beads packed models and Hele-Shaw cells were constructed, saturated with heavy-oil, and exposed to different types of solvents. The setup was continuously monitored to observe fluid fronts and asphaltene precipitation. The images were used in history matching to numerical models by mainly considering the permeability reduction due to asphaltene precipitation and the extent of interaction between solvent and oil phase.
Using this analysis, the mechanics of the process was clarified from the effect of solvent type on the recovery process point of view. The optimum solvent concentration and optimum operating temperature for hot solvent process were also identified.</jats:p
Hot solvent injection for heavy-oil and bitumen recovery
No full textThis research was undertaken to study the performance of paraffinic solvents at higher temperatures for heavy oil/bitumen recovery. Heavy oil or bitumen saturated glass bead packs, Berea sandstone and carbonate cores were used in the experiments to represent different types of pore structures, porosity and permeability.
Final recovery and the quantity of asphaltene precipitated in each experiment were reported. It was observed that recovery decreased with increasing temperature and pressure of the system and that the best results were obtained when the experimental temperature is slightly higher than the solvent saturation temperature. It was also noticed that butane diluted the oil more than propane.
Furthermore, numerical simulation was conducted using a commercial simulator including asphaltene precipitation option. Visualization experiments were also carried out using 2-D Hele-Shaw models to observe the effect of asphaltene precipitation on the dynamics of the process.
Using this analysis, the mechanics of the hot solvent process was clarified and the impact of temperature, pressure, asphaltene deposition, permeability and solvent type on recovery were quantified
Effects of dapagliflozin and liraglutide on metabolic control and cognition in high fat fed mice
No full text
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