Jogikal M. Jagadeesh

Menthol and nonmenthol cigarettes and smoke exposure in black and white women

Purposes of this investigation were to compare smoke constituent exposure (CO and nicotine boosts) and smoking topography parameters between black and white women, and between women regularly using menthol or nonmenthol cigarettes. A two-factor factorial design with a sample of 37 women stratified by race and menthol or nonmenthol cigarette use was implemented. There were significant main and interaction effects of race and menthol/nonmenthol use on CO boost. Black women had a mean CO boost of 10.1 ppm vs. 7.2 ppm for white women, while women using nonmenthol cigarettes had a higher CO boost (mean = 10.6 ppm) compared to those regularly using menthol cigarettes mean = 6.5 ppm). White menthol smokers had the lowest CO boost of all subgroups. There was a trend for black women to have higher nicotine boost than white women (21.4 ng/ml vs. 15.9 ng/ml). Black women had nonsignificantly higher puff volumes compared to white women (mean = 48.4 vs. 43.5 ml), while nonmenthol smokers had nonsignificantly higher puff volumes than menthol smokers (mean = 48.5 vs. 42.7 ml). Lower CO boost with mentholated cigarettes suggests factors beyond mentholation may affect elevated smoke constituent exposure among black women.

Wavelet and short-time Fourier transform analysis of electromyography for detection of back muscle fatigue

Measurement of the time-varying characteristics of the frequency content of trunk muscle electromyography is a method to quantify the amount of fatigue endured by workers during industrial tasks, as well as a tool that may guide the training and rehabilitation of healthy and injured workers. Quantification of the change of signal power within specific frequency ranges may shed greater insight into the fatigue process. Sixteen healthy male subjects performed isometric trunk extension at 70% of their maximum voluntary contraction. Surface electromyography from medial and lateral erector spinae, and latissimus dorsi locations were processed using the short-time Fourier transform (STFT) and wavelet transform. Linear regression quantified the time rate of change of median frequency as well as frequency specific STFT filter and wavelet scale measures. The median frequency from the short-time Fourier transform declined by 22 Hz/min from an initial value of 77 Hz on average. The wavelet and STFT filter measures demonstrated this decline to be caused by a reduction in 209-349 Hz signal power in addition to an increase in 7-88 Hz signal power. A significant reduction in median frequency and significant elevation in 13-22 Hz wavelet signal component was detected in about 90% of the cases, indicating their use for detecting and quantifying fatigue.

FAIR: a hardware architecture for real-time 3-D image registration

Mutual information-based image registration, shown to be effective in registering a range of medical images, is a computationally expensive process, with a typical execution time on the order of minutes on a modern single-processor computer. Accelerated execution of this process promises to enhance efficiency and therefore promote routine use of image registration clinically. This paper presents details of a hardware architecture for real-time three-dimensional (3-D) image registration. Real-time performance can be achieved by setting up a network of processing units, each with three independent memory buses: one each for the two image memories and one for the mutual histogram memory. Memory access parallelization and pipelining, by design, allow each processing unit to be 25 times faster than a processor with the same bus speed, when calculating mutual information using partial volume interpolation. Our architecture provides superior per-processor performance at a lower cost compared to a parallel supercomputer.

Design and assembly of an 8 tesla whole-body MR scanner.

PURPOSE The purpose of this report is to describe the design and construction of an 8 T/80 cm whole-body MRI system operating at 340 MHz. METHOD The 8 T/80 cm magnet was constructed from 414 km of niobium titanium superconducting wire. The winding of this wire on four aluminum formers resulted in a total inductance of 4,155 H. Gradient subsystems included either a body gradient or a head gradient along with a removable shim insert. The magnet and gradient subsystems were interfaced to two spectrometers. These provided the control of the gradient amplifiers and the two sets of four RF power amplifiers. The latter provide in excess of 8 kW of RF power from 10 to 140 MHz and 10 kW of RF power from 245 to 345 MHz. A dedicated computer-controlled patient table was designed and assembled. The entire system is located in a clinical setting, facilitating patient-based studies. RESULTS The 8 T/80 cm magnet was energized without complication and achieved persistent operation using 198.9 A of current, thereby storing 81.5 MJ of magnetic energy. Exceptional performance was observed for nearly all components both in isolation and when combined within the complete system. CONCLUSION An 8 T/80 cm MRI system has been assembled. The magnet subsystem is extremely stable and is characterized by good homogeneity and acceptable boil-off rates.

FPGA-based acceleration of mutual information calculation for real-time 3D image registration

Real-time image registration is potentially an enabling technology for the effective and efficient use of many image-guided diagnostic and treatment procedures relying on multimodality image fusion or serial image comparison. Mutual information is currently the best known image similarity measure for multimodality image registration. Mutual information calculation is a memory-intensive task that does not benefit from cache-based memory architecture in standard software implementations (i.e., the calculation incurs a large number of cache misses). Previous attempts to perform image registration in real time focused on parallel supercomputer implementations, which achieved real-time performance using large, expensive supercomputers that are simply impractical for deployment in a hospital. We have developed a custom hardware architecture that, in a single-module PC-based implementation, achieves registration speeds comparable to those of a 64-processor parallel supercomputer. The single-module speedup results from using parallel memory access and parallel calculation pipelines. The total speedup can be increased by using several modules in parallel. The architecture is designed for linear, mutual information-based registration and can be extended to elastic (nonlinear) registration.

Wavelet-based detection of transients in biological signals

This paper presents two multiresolution algorithms for detection and separation of mixed signals using the wavelet transform. The first algorithm allows one to design a mother wavelet and its associated wavelet grid that guarantees the separation of signal components if information about the expected minimum signal time and frequency separation of the individual components is known. The second algorithm expands this idea to design two mother wavelets which are then combined to achieve the required separation otherwise impossible with a single wavelet. Potential applications include many biological signals such as ECG, EKG, and retinal signals.

FPGA-based 3D median filtering using word-parallel systolic arrays

A 3D median filter architecture suitable for FPGA implementation is presented. The architecture consists of an ordered semi-systolic array of size equal to the filter window size. The hardware requirements of the architecture are significantly lower than those of previously reported systolic array architectures, making it desirable for the implementation of filters with large kernel sizes. An implementation of a 3/spl times/3/spl times/3/spl times/ filter in an Altera EP1C3T100C6 FPGA achieved a clock rate in excess of 100 MHz, being able to process a 128/spl times/128/spl times/128 image in 0.2 seconds. An implementation of a 3/spl times/3 2D filter achieved a clock rate in excess of 130 MHz.

Multiresolution Estimation of Motion using the Wavelet Transform

Many applications in research, in manufacturing and in every day life require measurement of velocity. Generally the velocity is estimated from a sequence of images. There are many methods reported in the literature using heuristics and transform techniques. In general these methods are tailored to specific applications. We propose a wavelet transform based technique to estimate velocity. We assume that the scene can be piecewise modeled by a multi variable polynomial. We have derived wavelet functions that can be used to estimate velocity from components of the wavelet transform. The technique has been demonstrated for 1D analytical functions and the error is less than 0.5% for polynomials of finite degree, and less than 5% for sinusoids. For 2D sequence of images, the image space is represented by a spatio temporal cube, and partitioned into subcubes of different dimensions. Wavelet transform techniques can then be applied to these variable size segments at multiple resolution. To estimate the two velocity components Vx and Vy in this spatio temporal cube requires the solution of a system of 8 non linear equations. We are in the process of solving these non linear equations.

A method for collecting semithin epoxy serial sections for light microscopy and 3-D reconstruction

In the three-dimensional reconstruction of neuronal structure, it is imperative that ribbons of semithin or ultrathin sections be obtained. Resin-embedded semithin sections display better structural details than paraffin-embedded sections. The cutting and collecting of long ribbons of resin-embedded semithin sections using a microtome, requires the use of large troughs on glass knives. A simple plastic trough has been described which facilitates the collection of ribbons directly onto a coverslip. As the ribbons are formed, they are floated on a coverslip. The water in the trough is slowly drained through a tubing which is attached to a syringe. The ribbons settle on the coverslip, which is easily removed and placed on a hotplate to dry the sections.

Three dimensional thinning of octree encoded objects

Describes an efficient thinning algorithm for octree encoded objects. The algorithm takes advantage of special features of the octree data structure to greatly reduce the magnitude of the thinning procedure. Fundamental, optimized, low-level octree processing operations provide fast access to the encoded object data. Preservation of the topological and geometrical properties of the object is insured by strict connectivity and topology preserving constraints. The selection of the octree as the 3-D representation method was based on its emergence as a well organized and highly compressed data structure for three-dimensional data. It has also demonstrated its accessibility to image and object processing algorithms, display techniques and numerical analysis methods. Basic operations, directly applied to the octree encoded data, form the foundation of complex analysis algorithms like thinning.