Development of active microwave imaging techniques for applications in mammography

Breast cancer is the most common non - skin malignancy in women and a leading cause of female morality. A potentially important strategy for reducing this menace is the detection at an early stage . The invention of non-invasive and non-ionizing microwave technique, to reveal the internal structure of biological objects was a break through in the field of medical diagnostics. Electrical properties of biological tissues and their interaction with electromagmetic waves have direct impact on human life. This thesis focuses on theoretical and experimental investigations of active microwave imaging techniques for breast cancer detection.

Microstrip band rejection filter using open loop resonator

Design of a compact microstrip band reject filter is proposed. The device consists of an Open Loop Rectangular Resonator (OLRR) coupled to a microstrip line. The transmission line has a U-bend which enhances the coupling with the OLRR element and reduces the size of the filter. The filter can be made tunable by mounting variable capacitance to the system. Simulated and experimental results are presented.

Active Microwave Imaging for Breast Cancer Detection

Active microwave imaging is explored as an imaging modality for early detection of breast cancer. When exposed to microwaves, breast tumor exhibits electrical properties that are significantly different from that of healthy breast tissues. The two approaches of active microwave imaging — confocal microwave technique with measured reflected signals and microwave tomographic imaging with measured scattered signals are addressed here. Normal and malignant breast tissue samples of same person are subjected to study within 30 minutes of mastectomy. Corn syrup is used as coupling medium, as its dielectric parameters show good match with that of the normal breast tissue samples. As bandwidth of the transmitter is an important aspect in the time domain confocal microwave imaging approach, wideband bowtie antenna having 2:1 VSWR bandwidth of 46% is designed for the transmission and reception of microwave signals. Same antenna is used for microwave tomographic imaging too at the frequency of 3000 MHz. Experimentally obtained time domain results are substantiated by finite difference time domain (FDTD) analysis. 2-D tomographic images are reconstructed with the collected scattered data using distorted Born iterative method. Variations of dielectric permittivity in breast samples are distinguishable from the obtained permittivity profiles.

SRR loaded waveguide band rejection filter with adjustable bandwidth

The use of a split-ring resonator (SRR)-loaded waveguide for the design of a band-rejection filter with adjustable bandwidth is reported. The width of the stopband can be adjusted by suitably positioning the SRR array in the waveguide. The rejection band can be made very narrow by placing the array at the electric-field minimum. The stopband attenuation depends on the number of unit cells in the array.

Constraining the active tectonic deformation of Andaman-Nicobar Arc in the background of December 26,2004 Great Sumatra-Andaman Earthquake

The Andaman-Nicobar Islands in the Bay of Bengal lies in a zone where the Indian plate subducts beneath the Burmese microplate, and therefore forms a belt of frequent earthquakes. Few efforts, not withstanding the available historical and instrumental data were not effectively used before the Mw 9.3 Sumatra-Andaman earthquake to draw any inference on the spatial and temporal distribution of large subduction zone earthquakes in this region. An attempt to constrain the active crustal deformation of the Andaman-Nicobar arc in the background of the December 26, 2004 Great Sumatra-Andaman megathrust earthquake is made here, thereby presenting a unique data set representing the pre-seismic convergence and co-seismic displacement.Understanding the mechanisms of the subduction zone earthquakes is both challenging sCientifically and important for assessing the related earthquake hazards. In many subduction zones, thrust earthquakes may have characteristic patterns in space and time. However, the mechanism of mega events still remains largely unresolved.Large subduction zone earthquakes are usually associated with high amplitude co-seismic deformation above the plate boundary megathrust and the elastic relaxation of the fore-arc. These are expressed as vertical changes in land level with the up-dip part of the rupture surface uplifted and the areas above the down-dip edge subsided. One of the most characteristic pattern associated with the inter-seismic era is that the deformation is in an opposite sense that of co-seismic period.This work was started in 2002 to understand the tectonic deformation along the Andaman-Nicobar arc using seismological, geological and geodetic data. The occurrence of the 2004 megathrust earthquake gave a new dimension to this study, by providing an opportunity to examine the co-seismic deformation associated with the greatest earthquake to have occurred since the advent of Global Positioning System (GPS) and broadband seismometry. The major objectives of this study are to assess the pre-seismic stress regimes, to determine the pre-seismic convergence rate, to analyze and interpret the pattern of co-seismic displacement and slip on various segments and to look out for any possible recurrence interval for megathrust event occurrence for Andaman-Nicobar subduction zone. This thesis is arranged in six chapters with further subdivisions dealing all the above aspects.

Characteristics of ABL during active and weak phases of monsoon

Understanding of the Atmospheric Boundary Layer (ABL) is imperative in the arena of the monsoon field. Here, the features of the ABL are studied employing Conserved Variable Analysis (CVA) using equivalent potential temperature and humidity. In addition, virtual potential temperature and wind are used during active and weak phases of monsoon. The analysis is carried out utilising the radiosonde observations during the monsoon months for two stations situated in the west coast of India. All these parameters show considerable variations during active and weak monsoon phases in both the stations. The core speed and core height vary with these epochs. The core speed is found to be more than 38 knots in the active monsoon phase around 1.2 km over Trivandrum and around 2 km over Mangalore. But during weak monsoon phase the core wind speed is decreased and core height is elevated over both stations. The wind direction shows an additional along shore component during weak monsoon period. The Convective Boundary Layer (CBL) height shows increase during weak monsoon phase over both stations due to less cloudiness and subsequent insolation. The CBL height during the southwest monsoon is more over Mangalore and is attributed by the orographic lifting in the windward side of the Western Ghats while the influence of the Ghats is less over Trivandrum.

Performance analysis of FIR digital filter design: RNS versus traditional

Residue Number System (RNS) based Finite Impulse Response (FIR) digital filters and traditional FIR filters. This research is motivated by the importance of an efficient filter implementation for digital signal processing. The comparison is done in terms of speed and area requirement for various filter specifications. RNS based FIR filters operate more than three times faster and consumes only about 60% of the area than traditional filter when number of filter taps is more than 32. The area for RNS filter is increasing at a lesser rate than that for traditional resulting in lower power consumption. RNS is a nonweighted number system without carry propogation between different residue digits.This enables simultaneous parallel processing on all the digits resulting in high speed addition and multiplication in the RNS domain

RNS based programmable multi-mode decimation filter for WCDMA and WiMAX

The recent trends envisage multi-standard architectures as a promising solution for the future wireless transceivers to attain higher system capacities and data rates. The computationally intensive decimation filter plays an important role in channel selection for multi-mode systems. An efficient reconfigurable implementation is a key to achieve low power consumption. To this end, this paper presents a dual-mode Residue Number System (RNS) based decimation filter which can be programmed for WCDMA and 802.16e standards. Decimation is done using multistage, multirate finite impulse response (FIR) filters. These FIR filters implemented in RNS domain offers high speed because of its carry free operation on smaller residues in parallel channels. Also, the FIR filters exhibit programmability to a selected standard by reconfiguring the hardware architecture. The total area is increased only by 24% to include WiMAX compared to a single mode WCDMA transceiver. In each mode, the unused parts of the overall architecture is powered down and bypassed to attain power saving. The performance of the proposed decimation filter in terms of critical path delay and area are tabulated.

Dual-mode RNS based programmable decimation filter for WCDMA and WLANa

The recent trends envisage multi-standard architectures as a promising solution for the future wireless transceivers. The computationally intensive decimation filter plays an important role in channel selection for multi-mode systems. An efficient reconfigurable implementation is a key to achieve low power consumption. To this end, this paper presents a dual-mode Residue Number System (RNS) based decimation filter which can be programmed for WCDMA and 802.11a standards. Decimation is done using multistage, multirate finite impulse response (FIR) filters. These FIR filters implemented in RNS domain offers high speed because of its carry free operation on smaller residues in parallel channels. Also, the FIR filters exhibit programmability to a selected standard by reconfiguring the hardware architecture. The total area is increased only by 33% to include WLANa compared to a single mode WCDMA transceiver. In each mode, the unused parts of the overall architecture is powered down and bypassed to attain power saving. The performance of the proposed decimation filter in terms of critical path delay and area are tabulated

Decimation Filter Design Toolbox for Multi-Standard Wireless Transceivers using MATLAB.

The demand for new telecommunication services requiring higher capacities, data rates and different operating modes have motivated the development of new generation multi-standard wireless transceivers. A multi-standard design often involves extensive system level analysis and architectural partitioning, typically requiring extensive calculations. In this research, a decimation filter design tool for wireless communication standards consisting of GSM, WCDMA, WLANa, WLANb, WLANg and WiMAX is developed in MATLAB® using GUIDE environment for visual analysis. The user can select a required wireless communication standard, and obtain the corresponding multistage decimation filter implementation using this toolbox. The toolbox helps the user or design engineer to perform a quick design and analysis of decimation filter for multiple standards without doing extensive calculation of the underlying methods.

Synthesis And Characterization Ofpolystyrene Supportedcatalytically Active Poly(Amidoamine) Dendrimer-Palladium Nanoparticle Conjugates

Poly(amidoamine) dendrimers were synthesized on cross-linked aminomethyl polystyrene. Palladium complexes of supported dendrimers prepared by ligand exchange method were reduced to dendrimernanoparticle conjugates supported on polystyrene resin. The supported nanoparticles were used as heterogeneous catalysts for the Suzuki coupling between aryl boronic acids and aryl halides. Various factors affecting the catalysts performance were studied. Higher generation dendrimers gave well-defined nanoparticles without agglomeration and these particles showed good catalytic performance

Trypsin Inhibitor from Edible Mushroom Pleurotus floridanus Active against Proteases of Microbial Origin

Protease inhibitors can be versatile tools mainly in the fields of medicine, agriculture and food preservative applications. Fungi have been recognized as sources of protease inhibitors, although there are only few such reports on mushrooms. This work reports the purification and characterization of a trypsin inhibitor from the fruiting body of edible mushroom Pleurotus floridanus (PfTI) and its effect on the activity of microbial proteases. The protease inhibitor was purified up to 35-fold by DEAE-Sepharose ion exchange column, trypsin-Sepharose column and Sephadex G100 column. The isoelectric point of the inhibitor was 4.4, and its molecular mass was calculated as 37 kDa by SDS-PAGE and 38.3 kDa by MALDI-TOF. Inhibitory activity confirmation was by dot-blot analysis and zymographic activity staining. The specificity of the inhibitor toward trypsin was with Ki of 1.043×10−10 M. The inhibitor was thermostable up to 90 °C with maximal stability at 30 °C, active over a pH range of 4–10 against proteases from Aspergillus oryzae, Bacillus licheniformis, Bacillus sp. and Bacillus amyloliquefaciens. Results indicate the possibility of utilization of protease inhibitor from P. floridanus against serine proteases

High Selectivity Filter Employing Stepped Impedance Resonators, Series Capacitors and Defected Ground Structures for Ultra Wide Band Applications

The paper presents a compact planar Ultra Wide Band ¯lter employing folded stepped impedance resonators with series capacitors and dumb bell shaped defected ground structures. An interdigital quarter wavelength coupled line is used for achieving the band pass characteristics. The transmission zeros are produced by stepped impedance resonators. The ¯lter has steep roll o® rate and good attenuation in its lower and upper stop bands, contributed by the series capacitor and defected ground structures respectively.

Enhancement of Calcifications in Mammograms using Volterra Series based Quadratic Filter

The paper summarizes the design and implementation of a quadratic edge detection filter, based on Volterra series, for enhancing calcifications in mammograms. The proposed filter can account for much of the polynomial nonlinearities inherent in the input mammogram image and can replace the conventional edge detectors like Laplacian, gaussian etc. The filter gives rise to improved visualization and early detection of microcalcifications, which if left undetected, can lead to breast cancer. The performance of the filter is analyzed and found superior to conventional spatial edge detectors

Dissolved Folin Phenol Active Substances (Tannin and Lignin) in the Seawater along the West Coast of India

Information on the distribution of dissolved Folin phenol active substances (FPAS) such as tannin and lignin in the seawater along the west coast of India is provided. Notable amounts of FPAS (surface concentrations: 80 f.1gll to 147 f.1gll and bottom concentrations: 80 f.1gll to 116 f.1gll) were detected in the seawater along the coast. The distribution pattern brings about a general depth-wise decrease. A seaward decrease was observed in the southern stations whereas reverse was the case in northern stations. A significant negative correlation was observed between FPAS concentration and dissolved oxygen in sub-surface samples. The appreciable amounts of FPAS detected in the coastal waters indicate the presence of organic matter principally originating from terrestrial (upland and coastal marsh) ecosystems in the marine environment. In this context, they may be used as tracers to determine the fate of coastalborn dissolved organic matter in the ocean and to determine directly the relationship between allochthonous and autochthonous organic matter