A UNIFIED APPROACH FOR OPTIMIZATION OF SNAKUSCULES AND OVUSCULES

Automated image segmentation techniques are useful tools in biological image analysis and are an essential step in tracking applications. Typically, snakes or active contours are used for segmentation and they evolve under the influence of certain internal and external forces. Recently, a new class of shape-specific active contours have been introduced, which are known as Snakuscules and Ovuscules. These contours are based on a pair of concentric circles and ellipses as the shape templates, and the optimization is carried out by maximizing a contrast function between the outer and inner templates. In this paper, we present a unified approach to the formulation and optimization of Snakuscules and Ovuscules by considering a specific form of affine transformations acting on a pair of concentric circles. We show how the parameters of the affine transformation may be optimized for, to generate either Snakuscules or Ovuscules. Our approach allows for a unified formulation and relies only on generic regularization terms and not shape-specific regularization functions. We show how the calculations of the partial derivatives may be made efficient thanks to the Green's theorem. Results on synthesized as well as real data are presented.

Molecular Marriage through Partner Preferences in Covalent Cage Formation and Cage-to-Cage Transformation

Unprecedented self-sorting of three-dimensional purely organic cages driven by dynamic covalent bonds is described. Four different cages were first synthesized by condensation of two triamines and two dialdehydes separately. When a mixture of all the components was allowed to react, only two cages were formed, which suggests a high-fidelity self-recognition. The issue of the preference of one triamine for a particular dialdehyde was further probed by transforming a non-preferred combination to either of the two preferred combinations by reacting it with the appropriate triamine or dialdehyde.

A generic variant of NIST’s KAS2 key agreement protocol

We propose a generic three-pass key agreement protocol that is based on a certain kind of trapdoor one-way function family. When specialized to the RSA setting, the generic protocol yields the so-called KAS2 scheme that has recently been standardized by NIST. On the other hand, when specialized to the discrete log setting, we obtain a new protocol which we call DH2. An interesting feature of DH2 is that parties can use different groups (e.g., different elliptic curves). The generic protocol also has a hybrid implementation, where one party has an RSA key pair and the other party has a discrete log key pair. The security of KAS2 and DH2 is analyzed in an appropriate modification of the extended Canetti-Krawczyk security model.

Micro-shock wave assisted bacterial transformation

A gene is a unit of heredity in a living organism. It normally resides on a stretch of DNA that codes for a type of protein or for an RNA chain that has a function in the organism. All living things depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism’s cells and pass genetic traits to offspring. The gene has to be transferred to bacteria or eukaryotic cells for basic and applied molecular biology studies. Bacteria can uptake exogenous genetic material by three ways: conjugation, transduction and transformation. Genetic material is naturally transferred to bacteria in case of conjugation and transferred through bacteriophage in transduction. Transformation is the acquisition of exogenous genetic material through cell wall. The ability of bacteria of being transformed is called competency and those bacteria which have competency are competent cells. Divalent Calcium ions can make the bacteria competent and a heat shock can cause the bacteria to uptake DNA. But the heat shock method cannot be used for all the bacteria. In electroporation, a brief electric shock with an electric field of 10-20kV/cmmakes pores in the cell wall, facilitates the DNA to enter into the bacteria. Microprecipitates, microinjection, liposomes, and biological vectors are also used to transfer polar molecules like DNA into host cells.

Pressure induced structural phase transformation in TiN: a first-principles study

Titanium nitride (TiN), which is widely used for hard coatings, reportedly undergoes a pressure-induced structural phase transformation, from a NaCl to a CsCl structure, at similar to 7 GPa. In this paper, we use first-principles calculations based on density functional theory with a generalized gradient approximation of the exchange correlation energy to determine the structural stability of this transformation. Our results show that the stress required for this structural transformation is substantially lower (by more than an order of magnitude) when it is deviatoric in nature vis-a-vis that under hydrostatic pressure. Local stability of the structure is assessed with phonon dispersion determined at different pressures, and we find that CsCl structure of TiN is expected to distort after the transformation. From the electronic structure calculations, we estimate the electrical conductivity of TiN in the CsCl structure to be about 5 times of that in NaCl structure, which should be observable experimentally. (C) 2013 American Institute of Physics. http://dx.doi.org/10.1063/1.4798591]

Power-law transformation for enhanced recognition of born-digital word images

In this paper, we discuss the issues related to word recognition in born-digital word images. We introduce a novel method of power-law transformation on the word image for binarization. We show the improvement in image binarization and the consequent increase in the recognition performance of OCR engine on the word image. The optimal value of gamma for a word image is automatically chosen by our algorithm with fixed stroke width threshold. We have exhaustively experimented our algorithm by varying the gamma and stroke width threshold value. By varying the gamma value, we found that our algorithm performed better than the results reported in the literature. On the ICDAR Robust Reading Systems Challenge-1: Word Recognition Task on born digital dataset, as compared to the recognition rate of 61.5% achieved by TH-OCR after suitable pre-processing by Yang et. al. and 63.4% by ABBYY Fine Reader (used as baseline by the competition organizers without any preprocessing), we achieved 82.9% using Omnipage OCR applied on the images after being processed by our algorithm.

Time variant reliability model updating in instrumented dynamical systems based on Girsanov's transformation

The problem of updating the reliability of instrumented structures based on measured response under random dynamic loading is considered. A solution strategy within the framework of Monte Carlo simulation based dynamic state estimation method and Girsanov's transformation for variance reduction is developed. For linear Gaussian state space models, the solution is developed based on continuous version of the Kalman filter, while, for non-linear and (or) non-Gaussian state space models, bootstrap particle filters are adopted. The controls to implement the Girsanov transformation are developed by solving a constrained non-linear optimization problem. Numerical illustrations include studies on a multi degree of freedom linear system and non-linear systems with geometric and (or) hereditary non-linearities and non-stationary random excitations.

Diaminotriazine substituted diphenyl ether: reversible structural transformation and solvent dependent solid state fluorescence

The effect of molecular shape and position of hydrogen bonding functionality in the solid state structural self-assembly was investigated using diaminotriazine substituted diphenyl ether based positional isomers (1-5). The molecular shape was modulated by changing diaminotriazine position that produced channel supramolecular structures in 1, 3 and 5. There exists a direct correlation between the molecular shape and three dimensional structures; more linear molecules resulted in close-packing whereas molecules with a labyrinthine topology formed a channel structure. Supramolecular aspects pertaining to the influence of solvent of crystallization in structure formation and reversible structural transformation in solid state were also explored. 1-5 exhibited tunable solid state fluorescence (lambda(max) = 437-496 nm) depending on the diaminotriazine substitutional position and 3 showed solvent-dependent solid state fluorescence. The present study describes the generation of a supramolecular channel structure with functional properties such as tunable fluorescence by varying the position of hydrogen bond functionality and solvent of crystallization.

Bimetallic core-shell nanocomposites using weak reducing agent and their transformation to alloy nanostructures

An in situ seeding growth methodology towards the preparation of core-shell nanoparticles composed of noble metals has been developed by employing trimethylamine borane (TMAB) as the reducing agent. Being a weak reducing agent, TMAB is able to distinguish the smallest reduction potential window of any two metals which renders selective reduction of metal ions thus affording a core-shell architecture of the nanoparticles. A dramatic effect of solvent was noted during the reduction of Ag+ ions: an immediate reduction took place at room temperature when dry THF was used as solvent however, usage of wet THF (THF used directly from the bottle) brings out the reduction only at reflux conditions. In the case of Au and Pd nanoparticles, preparation was found to be independent of the quality of solvent used. Au nanoparticles are realized at room temperature whereas reflux conditions are required in the case of Pd nanoparticles. This difference in behavior of the monometallic nanoparticles was successfully exploited to construct different noble metal nanoparticles with core-shell architectures such as Au@Ag, Ag@Au, and Ag@Pd. Transformation of these core-shell nanoparticles to their thermodynamically stable alloy counterparts is also demonstrated under very mild conditions reported to date.

Heat and mass transfer and chemical transformation in a cerium nitrate droplet

This paper deals with the thermo-physical changes that a droplet undergoes when it is radiatively heated in a levitated environment. The heat and mass transport model has been developed along with chemical kinetics within a cerium nitrate droplet. The chemical transformation of cerium nitrate to ceria during the process is predicted using Kramers' reaction mechanism which justifies the formation of ceria at a very low temperature as observed in experiments. The rate equation modeled by Kramers is modified suitably to be applicable within the framework of a droplet, and predicts experimental results well in both bulk form of cerium nitrate and in aqueous cerium nitrate droplet. The dependence of dissociation reaction rate on droplet size is determined and the transient mass concentration of unreacted cerium nitrate is reported. The model is validated with experiments both for liquid phase vaporization and chemical reaction. Vaporization and chemical conversion are simulated for different ambient conditions. The competitive effects of sensible heating rate and the rate of vaporization with diffusion of cerium nitrate is seen to play a key role in determining the mass fraction of ceria formed within the droplet. Spatially resolved modeling of the droplet enables the understanding of the conversion of chemical species in more detail.

Isothermal transformation of beta-phase in Cu-rich Cu-Al-Sn alloys

Microstructural changes resulting from isothermal decomposition of the beta-phase have been studied in Cu-rich binary Cu-Al and ternary Cu-Al-Sn alloys containing up to 3 at.% Sn at temperatures from 873 to 673 K. Results are presented as TTT diagrams. The decomposition occurs in several stages, each of which involves the establishment of metastable equilibrium between beta and one or more of the product phases alpha, beta(1) and gamma(2). Addition of Sn has been shown to increase the stability of the ordered beta(1)-phase in relation to beta. In alloys containing more than 2 at.% Sn, the beta(1) emerges as a stable phase. At low Sn concentrations beta(1) is metastable. An important new finding is the existence of three-phase equilibrium microstructure containing alpha, beta(1) and gamma(2). Increasing addition of Sn alters the morphology of beta(1) from rosettes to dendrites and finally to Widmanstatten needles.

Electron microscopy of microstructural transformation in electrodeposited Ni-rich, Ag-Ni film

Ag-Ni films were electrodeposited over a Cu substrate. Structural characterization revealed a fibrous microstructure with an amorphous structure for the as-deposited film. Isothermal annealing at 400 degrees C of the film inside transmission electron microscope led to amorphous-to-crystalline transition along with the evolution of nano-sized particles in the microstructure. The crystalline phase was Ni-Ag solid solution. The relative volume fraction of the nano-sized particles increased gradually with time. There was however no detectable decomposition of solid solution phase till about 4 h of annealing. Beyond 4 h phase separation initiated and pure Ag and Ni phases formed in the film. This study provides a methodology by which microstructural engineering of as-electrodeposited amorphous Ag-Ni films can be conducted to isolate a particular microstructure in order to tap specific potentially usable functionalities. (C) 2013 Elsevier B.V. All rights reserved.

Time variant reliability model updating in instrumented dynamical systems based on Girsanov’s transformation

The problem of updating the reliability of instrumented structures based on measured response under random dynamic loading is considered. A solution strategy within the framework of Monte Carlo simulation based dynamic state estimation method and Girsanov’s transformation for variance reduction is developed. For linear Gaussian state space models, the solution is developed based on continuous version of the Kalman filter, while, for non-linear and (or) non-Gaussian state space models, bootstrap particle filters are adopted. The controls to implement the Girsanov transformation are developed by solving a constrained non-linear optimization problem. Numerical illustrations include studies on a multi degree of freedom linear system and non-linear systems with geometric and (or) hereditary non-linearities and non-stationary random excitations.

A scaled unscented transformation based directed Gaussian sum filter for nonlinear dynamic system identification

Impoverishment of particles, i.e. the discretely simulated sample paths of the process dynamics, poses a major obstacle in employing the particle filters for large dimensional nonlinear system identification. A known route of alleviating this impoverishment, i.e. of using an exponentially increasing ensemble size vis-a-vis the system dimension, remains computationally infeasible in most cases of practical importance. In this work, we explore the possibility of unscented transformation on Gaussian random variables, as incorporated within a scaled Gaussian sum stochastic filter, as a means of applying the nonlinear stochastic filtering theory to higher dimensional structural system identification problems. As an additional strategy to reconcile the evolving process dynamics with the observation history, the proposed filtering scheme also modifies the process model via the incorporation of gain-weighted innovation terms. The reported numerical work on the identification of structural dynamic models of dimension up to 100 is indicative of the potential of the proposed filter in realizing the stated aim of successfully treating relatively larger dimensional filtering problems. (C) 2013 Elsevier Ltd. All rights reserved.

Copper-Catalyzed Oxidative Transformation of Secondary Alcohols to 1,5-Disubstituted Tetrazoles

A mild and convenient oxidative transformation of secondary alcohols to 1,5-disubstituted tetrazoles is uncovered by employing trimethylsilyl azide (TMSN3) as a nitrogen source in the presence of a catalytic amount of copper(II) perchlorate hexahydrate Cu(ClO4)(2)(.)6H(2)O] (5mol%) and 2,3-dichloro-5,6-dicyano-para-benzoquinone (DDQ) (1.2equiv.) as an oxidant. This reaction is performed under ambient conditions and proceeds through CC bond cleavage.