Spotted cDNA microarrays are emerging as a powerful and cost-effective tool for large-scale analysis of gene expression. Microarrays can be used to measure the relative quantities of specific mRNAs in two or more tissue samples for thousands of genes simultaneously. While the power of this technology has been recognized, many open questions remain about appropriate analysis of microarray data. One question is how to make valid estimates of the relative expression for genes that are not biased by ancillary sources of variation. Recognizing that there is inherent "noise" in microarray data, how does one estimate the error variation associated with an estimated change in expression, i.e., how does one construct the error bars? We demonstrate that ANOVA methods can be used to normalize microarray data and provide estimates of changes in gene expression that are corrected for potential confounding effects. This approach establishes a framework for the general analysis and interpretation of microarray data.

/pdf/analysis-of-variance-for-gene-expression-microarray-data-4ah49g72la.pdf

Analysis of Variance for Gene Expression Microarray Data

We consider the problem of inferring fold changes in gene expression from cDNA microarray data. Standard procedures focus on the ratio of measured fluorescent intensities at each spot on the microarray, but to do so is to ignore the fact that the variation of such ratios is not constant. Estimates of gene expression changes are derived within a simple hierarchical model that accounts for measurement error and fluctuations in absolute gene expression levels. Significant gene expression changes are identified by deriving the posterior odds of change within a similar model. The methods are tested via simulation and are applied to a panel of Escherichia coli microarrays.

/pdf/on-differential-variability-of-expression-ratios-improving-xh37jbqe33.pdf

On differential variability of expression ratios: improving statistical inference about gene expression changes from microarray data.

Light microscopy provides a simple, cost-effective, and vital method for the diagnosis and screening of hematologic and infectious diseases. In many regions of the world, however, the required equipment is either unavailable or insufficiently portable, and operators may not possess adequate training to make full use of the images obtained. Counterintuitively, these same regions are often well served by mobile phone networks, suggesting the possibility of leveraging portable, camera-enabled mobile phones for diagnostic imaging and telemedicine. Toward this end we have built a mobile phone-mounted light microscope and demonstrated its potential for clinical use by imaging P. falciparum-infected and sickle red blood cells in brightfield and M. tuberculosis-infected sputum samples in fluorescence with LED excitation. In all cases resolution exceeded that necessary to detect blood cell and microorganism morphology, and with the tuberculosis samples we took further advantage of the digitized images to demonstrate automated bacillus counting via image analysis software. We expect such a telemedicine system for global healthcare via mobile phone – offering inexpensive brightfield and fluorescence microscopy integrated with automated image analysis – to provide an important tool for disease diagnosis and screening, particularly in the developing world and rural areas where laboratory facilities are scarce but mobile phone infrastructure is extensive.

/pdf/mobile-phone-based-clinical-microscopy-for-global-health-3siutbfblo.pdf

Mobile phone based clinical microscopy for global health applications.

Mobile-health

Rapid advances in information technology and telecommunications - and, more specifically, wireless and mobile communications - and their convergence ("telematics") are leading to the emergence of a new type of information infrastructure that has the potential of supporting an array of advanced services for healthcare. The objective of this paper is to provide a snapshot of the applications of wireless telemedicine systems. A review of the spectrum of these applications and the potential benefits of these efforts is presented, followed by successful case studies in electronic patient record, emergency telemedicine, teleradiology, and home monitoring. It is anticipated that the progress carried out in these efforts and the potential benefits of emerging mobile technologies will trigger the development of more applications, thus enabling the offering of a better service to the citizen.

/pdf/wireless-telemedicine-systems-an-overview-2sr831wqee.pdf

Wireless telemedicine systems: an overview

The movement of telemedicine from desktop platforms to wireless and mobile configurations may have a significant impact on future health care. This paper reviews some of the latest technologies in wireless communication and their application in health care. The new technologies can make the remote medical monitoring, consulting, and health care more flexible and convenient. But, there are challenges for successful wireless telemedicine, which are addressed in this paper.

Mobile e-Health: The Unwired Evolution of Telemedicine

Microarray imaging is considered an important tool for large scale analysis of gene expression. The accuracy of the gene expression depends on the experiment itself and further image processing. It's well known that the noises introduced during the experiment will greatly affect the accuracy of the gene expression. How to eliminate the effect of the noise constitutes a challenging problem in microarray analysis. Traditionally, statistical methods are used to estimate the noises while the microarray images are being processed. In this paper, we present a new approach to deal with the noise inherent in the microarray image processing procedure. That is, to denoise the image noises before further image processing using stationary wavelet transform (SWT). The time invariant characteristic of SWT is particularly useful in image denoising. The testing result on sample microarray images has shown an enhanced image quality. The results also show that it has a superior performance than conventional discrete wavelet transform and widely used adaptive Wiener filter in this procedure.

/pdf/microarray-image-enhancement-by-denoising-using-stationary-2cwhnw4tog.pdf

Microarray image enhancement by denoising using stationary wavelet transform

This paper presents a novel approach to recognize the microarray image spots. The approach is based on the detection of wavelet modulus maxima in the microarray images. The detected maxima is actually the contour of the spots and thus the spots are recognized precisely. Then, the intensities within the contour of the spots can be obtained with low error rate. The test results on example image show this is an effective approach, especially for those spots with low intensities.

/pdf/application-of-wavelet-modulus-maxima-in-microarray-spots-3hg2puqu6u.pdf

Application of wavelet modulus maxima in microarray spots recognition

Sheath current can cause sheath loss and reduce the permissible current of a power cable transmission system. High sheath current is usually caused by mixed cable burying formation, different length between sections, poor connection of the bonding leads, and connection of distribution cable onto transmission systems. This paper analyses the characteristics of sheath circulating current at various conditions and presents a useful method to reduce it in a mixed burying formation system. It can effectively reduce the current by up to 90%. The method is validated by practical measurements and simulations using ATP, and has been implemented in actual systems. In addition, a special equipment is designed to measure and analyze the sheath circulating current. It can measure and analyze nine currents at a same time.

Characteristics and Reduction of Sheath Circulating Currents in Underground Power Cable Systems

For the power supply of the gradient coil set in Magnetic Resonance Imaging (MRI) system, i.e., the gradient driver, a highly stable flat-top current with a fast-rising stage and fast falling stage is needed. This article proposed a novel topology using partial power processing to generate the current repetitively, which can significantly reduce the switching frequency of all switching devices compared with conventional topologies, resulting in less switching loss and higher stability. Topology analysis and parameter design have been made for a 2000A peak current, 20ms flat-top, 500µs rising time, 1000 ppm stability application situation. And simulation results verified the proposed topology's superiority in lower switching frequency.

Yong Hua Song

Papers

Mobile e-Health: The Unwired Evolution of Telemedicine

Microarray image enhancement by denoising using stationary wavelet transform

Application of wavelet modulus maxima in microarray spots recognition

Characteristics and Reduction of Sheath Circulating Currents in Underground Power Cable Systems

A New Repetitive Flat-top Pulsed Magnetic Field Power Supply for Gradient Driver in MRI