Abstract

In this paper, biotin streptavidin interaction has been sensed at microwave frequencies with the help of designed sensor. It takes advantage of two pole filter topology where interdigitated capacitor (IDC) is used as a coupling zone between resonators for higher sensitivity. Due to permittivity change of biotin streptavidin combination, shift in resonant frequency arise whereas due to conductivity, magnitude of reflection coefficient changes. The frequency range of 10 GHz - 25 GHz (γ-dispersion region) is used as it is effective for label free analysis of biotin streptavidin. Due to homogeneous E-field between the fingers of IDC, placement position of biotin-streptavidin will not affect the sensitivity. Significant frequency shifts as high as 19 MHz, 45 MHz and 70 MHz are observed for concentrations as low as 10 ng/ml, 20 ng/ml and 30 ng/ml of biotin-streptavidin respectively. Simulation results suggest that proposed biosensor …

Abstract

GPUs with their massive Single Instruction Multiple Data (SIMD) capability have become attractive for scientific computation. The Kirchhoff-Helmholtz Transform (KHT) is a two dimensional integral commonly used in numerical reconstruction of the object from its experimentally measured diffraction pattern (called hologram). We explore the evaluation of KHT using GPU at various levels of optimisation. These optimisations are of two types:(a) algorithmic: exploiting the symmetries inherent in KHT, and (b) programmatic: optimizations that are specific to the GPU architecture like the lookup tables, scheduling of read/writes. From the numerical experiments, we report the speedup for each level of optimisation.

Abstract

Background Plant biologists have long speculated about the mechanisms that guide pollen tubes to ovules. Although there is now evidence that ovules emit a diffusible attractant, little is known about how this attractant mediates interactions between the pollen tube and the ovules. Results We employ a semi-in vitro assay, in which ovules dissected from Arabidopsis thaliana are arranged around a cut style on artificial medium, to elucidate how ovules release the attractant and how pollen tubes respond to it. Analysis of microscopy images of the semi-in vitro system shows that pollen tubes are more attracted to ovules that are incubated on the medium for longer times before pollen tubes emerge from the cut style. The responses of tubes are consistent with their sensing a gradient of an attractant at 100-150 μm, farther than previously reported. Our …

Abstract

Cells from animals adhere to and exert mechanical forces on their surroundings. Cells must control these forces for many biological processes, and dysfunction can lead to pathologies. How the actions of molecules within a cell are coordinated to regulate the adhesive interaction with the extracellular matrix remains poorly understood. It has been observed that cytoplasmic proteins that link integrin cell-surface receptors with the actin cytoskeleton flow with varying rates from the leading edge toward the center of a cell. Here, we explore theoretically how measurable subcellular traction stresses depend on the local speed of retrograde actin flow. In the model, forces result from the stretching of molecular complexes in response to the drag from the flow; because these complexes break with extension-dependent kinetics, the flow results in a decrease in their number when sufficiently large. Competition between these

Abstract

Projection of a Markov process with constant rates of transition to a small number of observable aggregated states can result in complex kinetics with memory. Here, we define the entropy production along a single sequence of aggregated states and show that it obeys detailed and integral fluctuation theorems. More importantly, we prove that projection shifts the distribution of entropy production over the ensemble of paths for a nonequilibrium process toward one characteristic of a system at equilibrium. This statement represents an analog of the second law of thermodynamics for path-dependent entropies and thus a new form of constraint of irreversible systems. Numeric examples are presented to illustrate these ideas.