1,026 research outputs found
First person – Kunal Chopra
No full textFirst Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping early-career researchers promote themselves alongside their papers. Kunal Chopra is first author on ‘Zebrafish duox mutations provide a model for human congenital hypothyroidism’, published in BIO. Kunal is a PhD student in the lab of Enrique Amaya at the University of Manchester, investigating reactive oxygen species in wound healing and regeneration
Differentially Private Combinatorial Optimization
No full textConsider the following problem: given a metric space, some of whose points are ``clients,'' select a set of at most facility locations to minimize the average distance from the clients to their nearest facility. This is just the well-studied -median problem, for which many approximation algorithms and hardness results are known. Note that the objective function encourages opening facilities in areas where there are many clients, and given a solution, it is often possible to get a good idea of where the clients are located. This raises the following quandary: what if the locations of the clients are sensitive information that we would like to keep private? emph{Is it even possible to design good algorithms for this problem that preserve the privacy of the clients?}
In this paper, we initiate a systematic study of algorithms for discrete optimization problems in the framework of differential privacy (which formalizes the idea of protecting the privacy of individual input elements). We show that many such problems indeed have good approximation algorithms that preserve differential privacy; this is even in cases where it is impossible to preserve cryptographic definitions of privacy while computing any non-trivial approximation to even the emph{value} of an optimal solution, let alone the entire solution.
Apart from the -median problem, we consider the problems of vertex and set cover, min-cut, facility location, and Steiner tree, and give approximation algorithms and lower bounds for these problems. We also consider the recently introduced submodular maximization problem, ``Combinatorial Public Projects'' (CPP), shown by Papadimitriou et al. cite{PSS08} to be inapproximable to subpolynomial multiplicative factors by any efficient and emph{truthful} algorithm. We give a differentially private (and hence approximately truthful) algorithm that achieves a logarithmic additive approximation.
Joint work with Anupam Gupta, Katrina Ligett, Frank McSherry and Aaron Roth
Supplemental Data: Olfactory Receptor 78 modulates renin but not baseline blood pressure
No full textSupplementary Data: Olfactory Receptor 78 modulates renin but not baseline blood pressureBrian G. Poll, Jiaojiao Xu, Kunal Gupta, Tyler B. Shubitowski, Jennifer L. PluznickIncludes: Supplemental Figure 1: Generation of the Olfr78fl/fl mouse.Supplemental Figure 2: Effects of Salt Diet on weight in Olfr78KO mice.Supplemental Figure 3: Urine Electrolytes in ReninCre (WT) and ReninCreOlfr78fl/fl (KO) mice.Supplemental Table 1: Plasma chemistry of ReninCre Mice<br
sj-pdf-1-vmj-10.1177_1358863X231205574 – Supplemental material for Impact of preexisting coronary artery and peripheral artery disease on outcomes in diabetic patients after kidney transplant
No full textSupplemental material, sj-pdf-1-vmj-10.1177_1358863X231205574 for Impact of preexisting coronary artery and peripheral artery disease on outcomes in diabetic patients after kidney transplant by Sania Jiwani, Wan-Chi Chan, Monil Majmundar, Kunal N Patel, Harsh Mehta, Aditya Sharma, Gaurav Parmar, Mark Wiley, Peter Tadros, Eric Hockstad, Sri G Yarlagadda, Aditi Gupta and Kamal Gupta in Vascular Medicine</p
INDEPENDENT HEROES: Supporting Type 1 Diabetic Young Adults’ Transition to Independent Living
No full textThis Master of Design Thesis project focuses on the condition of severe hypoglycemia (low blood sugar) in young adults living with type 1 diabetes by carefully understanding the unique challenges they face in transitioning to adult care. This research surfaces the needs that often get blurred in the transition process and offers a design for an appropriate solution to support the identified issues. Canadian young adults living with type 1 diabetes often find themselves at the risk of hypoglycemia during emerging adulthood. The concept of emerging adulthood has not been considered extensively in managing chronic illness and transition from pediatric to adult care. Yet, this is a critical time when a person may first assume full responsibility for their diabetes self-care while simultaneously facing all the usual challenges young adults face. Additionally, the fear of hypoglycemia is strongest in this group. A review of the literature informs us about previous work done in this field. However, most current interventions are in the form of bulky printed materials. Another critical issue with the development of most recent tools is the absence of user involvement in the creative process leading to unmet user needs. In this project, participatory design methodologies were introduced in a human-centered approach, collaborating with young adults to understand and address the transition process gap. It included actively listening to user narratives and co-creating the solution. The synthesis of primary and secondary research resulted in the designed outcome of a smart wearable device that will work in conjunction with the Continuous glucose monitor (CGM) and alerts the bystander and emergency contacts by turning them into potential lifesavers. It will inform them of a diabetic emergency and guide them through the life-saving instructions. Additionally, it will alert the medical emergency services for prompt assistance if needed. The solution attempts to provide early intervention during emergency and could also alleviate the fear of hypoglycemia in young adults. This in turn will reduce the load on the already burdened healthcare system
Charge carrier dynamics in PffBT4T-2OD: PCBM organic solar cells
No full textWe investigate the charge carrier dynamics of inverted organic solar cells (OSCs) based on PffBT4T-2OD: PCBM and PTB7: PCBM - the two leading systems among the OSCs based on polymer-fullerene bulk-heterojunction - to elucidate the origin of their performance difference. Transient absorption spectroscopy (TAS) and photo-electrochemical impedance spectroscopy (photo-EIS) were employed to unravel the photo-physics that govern the cell operation of these two highly efficient bulk heterojunction OSCs. While photo-EIS indicates that the two systems under study exhibit similar behavior in terms of recombination, TAS results reveal that PffBT4T-2OD: PCBM systems not only have higher charge generation rate but also more efficient charge transfer than PTB7: PCBM systems, leading to the power conversion efficiency of PffBT4T-2OD: PCBM-based OSCs (9.16%) that is higher than that of PTB7: PCBM-based OSCs (6.44%).
Watershed modeling using HEC-RAS, HEC-HMS, and GIS models: a case study of the Wreck Pond Brook Watershed in Monmouth County, New Jersey
No full textManaging stormwater on a watershed basis is considered the best strategy to address flooding. A watershed model should provide temporal and spatial distribution of runoff response for a given storm. GIS applicability in watershed modeling is increasing due to the availability of spatial information, fast processors and interfaces such as ArcHydro, HEC-GeoHMS, and HEC-GeoRAS linking hydrologic and hydraulic models to the ArcGIS environment.
Soil Conservation Service methods are used widely in hydrologic models. Several parameters inherent to these empirical methods are average values derived from various watershed conditions. These average values overestimate peak flows for flat, low-lying coastal terrains. The design of flood control structures based on these flow values allow more post-development discharge, make the system more hydraulically efficient, increase project costs, and cause flooding for areas downstream. In this study, Wreck Pond Brook Watershed (WPBW), a coastal New Jersey area was used for sensitivity studies of the initial abstraction ratio and peak rate factor. The HEC-HMS modeling results indicated use of a lower peak rate factor (e.g. 284) and 5% initial abstraction ratio provided better characterization of stream response. These updated parameters provide new technical information for improving stormwater management in coastal areas.
An important limitation in hydraulic modeling is the economic constraint on cross-section spacing for surveying channels and floodplains. Applying GIS techniques in hydraulic modeling eliminated this constraint. Floodplain analysis was done using ArcGIS, HEC-GeoRAS and HEC-RAS. Detailed elevation data (LIDAR information from Monmouth County) was incorporated into the HEC-RAS using GIS models. This innovation was important for improving model efficiency. The modeled floodplain demonstrated close agreement to the observed floodplain for the October 2005 storm and showed greater accuracy compared to the FEMA floodplain for the 100-year storm. This study validated use of LIDAR elevation data in floodplain analysis for the second-order streams in coastal NJ.
Finally, an approach was demonstrated using modeled floodplain and HEC-HMS for flood control analysis. This study presents an innovative watershed modeling approach using GIS models while addressing the limitations of traditional hydrologic and hydraulic methods using WPBW as an example.Ph.D.Includes bibliographical references (p. 259-263)by Kunal P. Pate
Online_Supp – Supplemental material for A pilot study of the utility of cerebrospinal fluid neurofilament light chain in differentiating neurodegenerative from psychiatric disorders: A ‘C-reactive protein’ for psychiatrists and neurologists?
No full textSupplemental material, Online_Supp for A pilot study of the utility of cerebrospinal fluid neurofilament light chain in differentiating neurodegenerative from psychiatric disorders: A ‘C-reactive protein’ for psychiatrists and neurologists? by Dhamidhu Eratne, Samantha M Loi, Nirbaanjot Walia, Sarah Farrand, Qiao-Xin Li, Shiji Varghese, Mark Walterfang, Andrew Evans, Ramon Mocellin, Kunal Dhiman, Veer Gupta, Charles B Malpas, Steven Collins, Colin L Masters and Dennis Velakoulis in Australian & New Zealand Journal of Psychiatry</p
Opportunities and challenges of investing in Indian real estate
No full textThesis (S.M.)--Massachusetts Institute of Technology, Program in Real Estate Development in Conjunction with the Center for Real Estate , 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 125-128).In recent years, global real estate investment has become an important component of efficient global mixed asset portfolios. Although these investments carry increased political, regulatory and currency risk, international real estate investment has been on the rise. Compelling macroeconomic and demographic trends along with improvements in structural and regulatory conditions and investment in infrastructure are driving strong real estate capital flows into the emerging markets. This thesis provides a study of the opportunities and challenges of investing in one emerging market, India. With a population of over 1 billion, India has been a major beneficiary of the "Globalization of Real Estate". This thesis identifies the opportunities in India that have caused global capital to flow into Indian real estate and the key factors driving Indian real estate. It explains the challenges of investing in Indian real estate and seeks to provide strategies for navigating the real estate landscape in India.by Kunal Wadhwani.S.M
Computational modeling of intrinsic dissipation in nano-structure
No full textIn this work, using computational modeling, we study the different mechanisms of intrinsic dissipation in nano-electro mechanical systems (NEMS). We, first, use molecular dynamics (MD) simulation and gain an understanding of the underlying loss mechanisms. Using insights from the MD simulation, a multi-scale method to model intrinsic damping is developed. The high frequency vibration in NEMS have important applications. A few examples include the sensing of atomic mass, detection of biological molecules and observation of quantum effects in macroscopic objects. For all these potential applications, dissipation plays a limiting role. While a number of experimental and theoretical studies have been performed, the individual role of different mechanisms remains unclear. In this work, we attempt to isolate and understand the surface and size effect on some of the intrinsic mechanisms. We, first, consider the case of the Akhiezer damping. The Akhiezer dynamics is expected to play an important role in nano-resonators with frequencies in the GHz range. Using a judiciously devised MD set-up, we isolate Akhiezer dynamics. We show that the surfaces aid in reducing the dissipation rate through increasing the rate of thermalization of the phonons. We, next, study damping under the flexure mode of operation. A comparative analysis with the stretching mode shows that the flexure mode is less dissipative. A reduced order model is considered to understand this novel behavior. We, also, investigate the role of tension on the Q factor, a measure of the inverse of dissipation rate.
From these studies, we conclude that Akhiezer dynamics plays a dominant role in nano-resonators. We, then, develop a quasi-harmonic based multi-scale method to model Akhiezer damping. A stress component, that characterizes the non-equilibrium phonon population, is derived. We obtain constitutive relation that governs the time evolution of the non-equilibrium stress. Different methods to parametrize the constitutive relation are discussed. Using the proposed formulation, we compute the dissipation rate for different cases. The results are compared with those obtained using MD. Next, we use the Boltzmann transport equation and investigate the Q factor due to the thermo-elastic dissipation (TED). The Q factor obtained shows deviations from the classical theory of TED. Correction to the classical formula, for the case of longitudinal modes, is provided.
We, then, study damping is low dimensional structure. We first consider the case of two dimensional graphene sheet and under in-plane stretching. We show that the coupling between the in-plane and the out-of-plane motions plays an important role in the loss of mechanical energy. Further, a hysteresis behavior in the out-of-plane dynamics is observed. Next, we investigate the stretching motion of graphene nano-ribbon. A normal mode Langevin dynamics is devised to understand the results from the MD simulation.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-05-01The student, Kumar Kunal, accepted the attached license on 2015-12-23 at 11:24.The student, Kumar Kunal, submitted this Dissertation for approval on 2015-12-23 at 11:27.This Dissertation was approved for publication on 2016-01-04 at 13:54.DSpace SAF Submission Ingestion Package generated from Vireo submission #9026 on 2016-07-07 at 13:48:03Made available in DSpace on 2016-07-07T20:26:39Z (GMT). No. of bitstreams: 2
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