Distributed and Parallel Algorithms for Set Cover Problems with Small Neighborhood Covers

In this paper, we study a class of set cover problems that satisfy a special property which we call the {\em small neighborhood cover} property. This class encompasses several well-studied problems including vertex cover, interval cover, bag interval cover and tree cover. We design unified distributed and parallel algorithms that can handle any set cover problem falling under the above framework and yield constant factor approximations. These algorithms run in polylogarithmic communication rounds in the distributed setting and are in NC, in the parallel setting.Comment: Full version of FSTTCS'13 pape

Encrypted Distributed Dictionaries

End-to-end encrypted databases have been heavily studied in the last two decades. A crucial aspect that previous work has neglected, however, is that real-world databases are distributed in the sense that data is partitioned among a cluster of nodes---as opposed to being stored on a single node. In this work, we initiate the study of encrypted distributed data structures which are end-to-end encrypted variants of distributed data structures; themselves fundamental to the design of distributed databases. In particular, we design and analyze encrypted variants of distributed dictionaries (EDDX), which are an important building block in distributed system design and have applications ranging from content delivery networks to off-chain storage networks for blockchains and smart contracts. We formalize the notion of an encrypted DDX and provide simulation-based security definitions that capture the security properties one would desire from such an object. We propose an EDDX construction that uses a distributed hash table (DHT) as a black box. Interestingly, we show that our construction leaks information probabilistically, where the probability is a function of how well the underlying DHT load balances its data. We also show that in order to be securely used with our construction, a plaintext DHT needs to satisfy a form of programmability , a property that usually only emerges in the context of cryptographic primitives. To show that these properties are indeed achievable in practice, we study the balancing properties of the Chord DHT---arguably one of the most influential DHT---and show that it is also programmable. Finally, we consider the problem of encrypted DDXs in the context of transient networks, where nodes can be arbitrarily added or removed from the network

Analysing the Differential Performances of Indian States in the Tourism Sector : (1947-early 2020)

Tourism is an ever evolving and a dynamic industry which can play a crucial role in increasing income and in providing employment opportunities in an economy. India especially with its rich heritage, culture and geographical landscapes has always had immense potential to become a leading tourist destination. Presently the major types of tourism prevalent in India are Medical Tourism, Rural/ Natural Tourism, Religious Tourism and Historical& Educational Tourism. In 2018-19, the tourism sector contributed around 5% to India’s GDP. However with the health shock of Covid-19, the tourism sector has taken a major hit since early 2020, with several people losing their jobs in the tourism and hospitality sector when different states imposed lockdowns and took various measures to curb the pandemic. As restrictions in each state eased during the first wave of the pandemic, different states in India adopted various policies to revive the tourism industry. But to understand the effectiveness of these policies in each state/ UT, one needs to investigate the baseline at which the Tourism industry was before the pandemic hit the country. This paper attempts to look at the differential performances of states and UTs of India in tourism by categorizing them into various types of tourism between 1947 until March 2020.This paper aims to act as a base for further analysing the impact of this pandemic on Tourism across states in India

Encrypted Blockchain Databases

Blockchain databases are storage systems that combine properties of blockchains and databases like decentralization, tamper-proofness, low query latency and support for complex queries. Blockchain databases are an emerging and important class of blockchain technology that is critical to the development of non-trivial smart contracts, distributed applications and decentralized marketplaces. In this work, we consider the problem of designing end-to-end encrypted blockchain databases to support the development of decentralized applications that need to store and query sensitive data. In particular, we show how to design what we call blockchain encrypted multi-maps (EMM) which can be used to instantiate various kinds of NoSQL blockchain databases like key-value stores or document databases. We propose three blockchain EMM constructions, each of which achieves different tradeoffs between query, add and delete efficiency. All of our constructions are legacy-friendly in the sense that they can be implemented on top of any existing blockchain. This is particularly challenging since blockchains do not support data deletion. We implemented our schemes on the Algorand blockchain and evaluated their concrete efficiency empirically. Our experiments show that they are practical

Encrypted Databases for Differential Privacy

The problem of privatizing statistical databases is a well-studied topic that has culminated with the notion of differential privacy. The complementary problem of securing these differentially private databases, however, has—as far as we know—not been considered in the past. While the security of private databases is in theory orthogonal to the problem of private statistical analysis (e.g., in the central model of differential privacy the curator is trusted) the recent real-world deployments of differentially-private systems suggest that it will become a problem of increasing importance. In this work, we consider the problem of designing encrypted databases (EDB) that support differentially-private statistical queries. More precisely, these EDBs should support a set of encrypted operations with which a curator can securely query and manage its data, and a set of private operations with which an analyst can privately analyze the data. Using such an EDB, a curator can securely outsource its database to an untrusted server (e.g., on-premise or in the cloud) while still allowing an analyst to privately query it. We show how to design an EDB that supports private histogram queries. As a building block, we introduce a differentially-private encrypted counter based on the binary mechanism of Chan et al. (ICALP, 2010). We then carefully combine multiple instances of this counter with a standard encrypted database scheme to support differentially-private histogram queries

New drug discovery of cardiac anti-arrhythmic drugs: insights in animal models

Abstract Cardiac rhythm regulated by micro-macroscopic structures of heart. Pacemaker abnormalities or disruptions in electrical conduction, lead to arrhythmic disorders may be benign, typical, threatening, ultimately fatal, occurs in clinical practice, patients on digitalis, anaesthesia or acute myocardial infarction. Both traditional and genetic animal models are: In-vitro: Isolated ventricular Myocytes, Guinea pig papillary muscles, Patch-Clamp Experiments, Porcine Atrial Myocytes, Guinea pig ventricular myocytes, Guinea pig papillary muscle: action potential and refractory period, Langendorff technique, Arrhythmia by acetylcholine or potassium. Acquired arrhythmia disorders: Transverse Aortic Constriction, Myocardial Ischemia, Complete Heart Block and AV Node Ablation, Chronic Tachypacing, Inflammation, Metabolic and Drug-Induced Arrhythmia. In-Vivo: Chemically induced arrhythmia: Aconitine antagonism, Digoxin-induced arrhythmia, Strophanthin/ouabain-induced arrhythmia, Adrenaline-induced arrhythmia, and Calcium-induced arrhythmia. Electrically induced arrhythmia: Ventricular fibrillation electrical threshold, Arrhythmia through programmed electrical stimulation, sudden coronary death in dogs, Exercise ventricular fibrillation. Genetic Arrhythmia: Channelopathies, Calcium Release Deficiency Syndrome, Long QT Syndrome, Short QT Syndrome, Brugada Syndrome. Genetic with Structural Heart Disease: Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia, Dilated Cardiomyopathy, Hypertrophic Cardiomyopathy, Atrial Fibrillation, Sick Sinus Syndrome, Atrioventricular Block, Preexcitation Syndrome. Arrhythmia in Pluripotent Stem Cell Cardiomyocytes. Conclusion: Both traditional and genetic, experimental models of cardiac arrhythmias’ characteristics and significance help in development of new antiarrhythmic drugs