Pattern Formation in Active Nematics

This thesis presents analytical and numerical studies of the nonequilibrium dynamics of active nematic liquid crystals. Active nematics are a new class of liquid crystals consisting of elongated rod-like units that convert energy into motion and spontaneously organize in large-scale structures with orientational order and self-sustained flows. Examples include suspensions of cytoskeletal filaments and associated motor proteins, monolayers of epithelial cells plated on a substrate, and bacteria swimming in a nematic liquid crystal. In these systems activity drives the continuous generation and annihilation of topological defects and streaming flows, resulting in spatio-temporal chaotic dynamics akin to fluid turbulence, but that occurs in a regime of flow of vanishing Reynolds number, where inertia is negligible. Quantifying the origin of this nonequilibrium dynamics has implications for understanding phenomena ranging from bacterial swarming to cytoplasmic flows in living cells. After a brief review (Chapter 2) of the properties of equilibrium or passive nematic liquid crystals, in Chapter 3 we discuss how the hydrodynamic equations of nematic liquid crystals can be modified to account for the effect of activity. We then use these equations of active nemato-hydrodynamics to characterize analytically the nonequilibrium steady states of the system and their stability. We supplement the analytical work with numerical solution of the full nonlinear equations for the active suspension and construct a phase diagram that identifies the various emergent patterns as a function of activity and nematic stiffness. In Chapter 4 we compare results obtained with two distinct hydrodynamic models that have been employed in previous studies. In both models we find that the chaotic spatio-temporal dynamics in the regime of fully developed active turbulence is controlled by a single active scale determined by the balance of active and elastic stresses. This work provides a unified understanding of apparent discrepancies in the previous literature and demonstrate that the essential physics is robust to the choice of model. Finally, in Chapter 5 we examine the dynamics of a compressible active nematic on a substrate. When frictional damping dominates over viscous dissipation, we eliminate flow in favor of active stresses to obtain a minimal model with renormalized elastic constants driven negative by activity. We show that spatially inhomogeneous patterns are selected via a mechanism analogous to that responsible for modulated phases at an equilibrium Lifshitz point

Deserializing and Exposing In-memory Columnar OLAP/OLTP Data

This disclosure describes high-performance techniques of using a client library to access data from OLAP or OLTP databases. Data is transported between the database and the client library in a columnar in-memory format such as Apache Arrow over a binary protocol such as RPC. RPC is significantly faster than REST when receiving data due to the use of protocol Buffers and HTTP/2. In addition, Apache Arrow is zero-copy and does efficient in-memory computations. The stream of data is processed in separate parser threads, thus maximizing concurrency and parallel processing. This makes the client library an order of magnitude faster than the legacy REST based implementations. The client library deserializes columnar in-memory data into rows such that callers of the client can retrieve data in a familiar backward-compatible format, e.g., java.sql.ResultSet (if the client library is written in Java), which acts as a data abstraction layer

Accelerometer based gesture recognition robot

Gesture recognition can be termed as an approach in this direction. It is the process by which the gestures made by the user are recognized by the receiver. Gestures are expressive, meaningful body motions involving physical movements of the fingers, hands, arms, head, face, or body with the intent of: conveying meaningful information orinteracting with the environment. They constitute one interesting small subspace of possible human motion. A gesture may also be perceived by the environment as a compression technique for the information to be transmitted elsewhere and subsequently reconstructed by the receiver. Classification hand and arm gestures: Recognition of hand poses, sign languages, and entertainment applications. head and face gestures: Nodding or shaking of head; direction of eye gaze; etc.; body gestures: involvement of full body motion, as in; tracking movements of two people interacting outdoors; analyzing movements of a dancer for generating matching music and graphics; Benefits: A human computer interface can be provided using gestures: Replace mouse and keyboard Pointing gestures Navigate in a virtual environment Pick up and manipulate virtual objects Interact with the 3D worl

Student Attendance System Based on Fingerprint Recognition and One to Many Matching

Our project aims at designing an student attendance system which could effectively manage attendance of students at institutes like NIT Rourkela. Attendance is marked after student identification. For student identification, a fingerprint recognition based identification system is used. Fingerprints are considered to be the best and fastest method for biometric identification. They are secure to use, unique for every person and does not change in one's lifetime. Fingerprint recognition is a mature field today, but still identifying individual from a set of enrolled fingerprints is a time taking process. It was our responsibility to improve the fingerprint identification system for implementation on large databases e.g. of an institute or a country etc. In this project, many new algorithms have been used e.g. gender estimation, key based one to many matching, removing boundary minutiae. Using these new algorithms, we have developed an identification system which is faster in implementation than any other available today in the market. Although we are using this fingerprint identification system for student identification purpose in our project, the matching results are so good that it could perform very well on large databases like that of a country like India (MNIC Project). This system was implemented in Matlab10, Intel Core2Duo processor and comparison of our one to many identification was done with existing identification technique i.e. one to one identification on same platform. Our matching technique runs in O(n+N) time as compared to the existing O(Nn^2). The fingerprint identification system was tested on FVC2004 and Verifinger databases

Role of phospholipid head groups in ethanol tolerance of Saccharomyces cerevisiae

Pre-incubation of cells of Saccharomyces cerevisiae with 2 M-ethanol led to decreased rates of L-alanine uptake, H+ efflux and fermentation rate. However, these responses were modified in yeast cells with altered phospholipid composition. Using L-alanine transport and H+ efflux as indices of ethanol tolerance, it was observed that cells enriched with phosphatidylserine had greater tolerance to ethanol. This resulted from altered charge of membrane phospholipids rather than changes in membrane fluidity. It is suggested that the anion:zwitterion ratio of phospholipids may be one of the important determinants of ethanol tolerance in S. cerevisiae

EVALUATING SAMPLING-BASED TECHNIQUE FOR IMPROVED SMALL OBJECT DETECTION USING APPROPRIATE SIZES OF THE ANCHOR BOXES

Abstract Small object detection is a challenging task in computer vision due to the limited spatial information and low resolution of these objects. Existing generic object detectors demonstrate satisfactory performance on medium and large-sized objects, but they often struggle to accurately recognize small objects. The challenges arise from the low resolution and simple shape characteristics typically associated with small objects. In this paper, we propose an up sampling-based method for end-to-end tiny object identification that outperforms the existing state-of-the-art methods. We, like other contemporary approaches, first produce suggestions before labeling them. In the event of somewhat little things, we recommend tweaks to both of these procedures

Mitochondrial dynamics and inheritance during cell division, development and disease

During cell division, it is critical to properly partition functional sets of organelles to each daughter cell. The partitioning of mitochondria shares some common features with that of other organelles, particularly in the use of interactions with cytoskeletal elements to facilitate delivery to the daughter cells. However, mitochondria have unique features — including their own genome and a maternal mode of germline transmission — that place additional demands on this process. Consequently, mechanisms have evolved to regulate mitochondrial segregation during cell division, oogenesis, fertilization and tissue development, as well as to ensure the integrity of these organelles and their DNA, including fusion–fission dynamics, organelle transport, mitophagy and genetic selection of functional genomes. Defects in these processes can lead to cell and tissue pathologies

Empowering others

We can all be honest, law-abiding citizens who are aware of our rights and responsibilities towards society and the nation. But being good citizens also requires us to contribute to society in ways that we can. Here’s what I decided to do