Structural Studies of DNA–Cationic Lipid Complexes Confined in Lithographically Patterned Microchannel Arrays

We have used lithographically patterned microchannel arrays with channel widths ranging from 1 to 20 m, fabricated using electron beam lithography and reactive ion etching, in structural studies of DNA–cationic lipid complexes in confinement. Various techniques have been developed for loading these DNA–membrane complexes into the microchannels or to form the complexes in situ by sequentially depositing DNA and lipid solutions into the microchannels. Optical microscopy studies indicate that such complex formation is strongly influenced by the periodic channel structure even at channel widths much larger than the persistent length of the DNA molecules. Preliminary x-ray diffraction experiments conducted at Stanford Synchrotron Radiation Laboratory (SSRL) yielded only a weak signal from the lipid bilayers in the complexes. The use of a microfocused x-ray beam produced by the newly developed Bragg–Fresnel optics at a third-generation synchrotron facility may dramatically increase the signal-to-noise ratio and allow observation of orientational as well as positional ordering of DNA molecules induced by the microchannels. Structural control of the DNA–membrane complexes has a broad range of potential applications in gene probe technology and as mesoscopic biomolecular composites.     

Organizational impact of system quality,information quality,and service quality

Increased organizational dependence on information systems drives management attention towards improving information systems’ quality. A recent survey shows that “Improve IT quality” is one of the top concerns facing IT executives. As IT quality is a multidimensional measure, it is important to determine what aspects of IT quality are critical to organizations to help Chief Information Officers (CIOs) to devise effective IT quality improvement strategies. In this research, we model the relationship between information systems’ (IS) quality and organizational impact. We hypothesize greater organizational impact in situations in which system quality, information quality and service quality are high. We also hypothesize a positive relationship between system quality and information quality. We test our hypotheses using survey data. Our structural equation model exhibits a good fit with the observed data. Our results show that IS service quality is the most influential variable in this model (followed by information quality and system quality), thus highlighting the importance of IS service quality for organizational performance. This paper contributes theoretically to IS success models through the system quality-to-information quality and IS quality-to-organizational impact links. Implications of our results for practice and research are discussed.     

Assessment of working conditions in two different semiconductor manufacturing lines: Effective ergonomics interventions

This article examines two manufacturing lines producing semiconductors using different technology concepts, namely Conventional Line (CL) and Lean Production Line (LPL). Both lines manufacturing the same products were compared using various factors, including working conditions, task risks and dangers of the job, and physical body stress. Ergonomic approaches were adopted in the investigation of the two lines. Survey questionnaires were administered to 30% of the workers, and multiple statistical tests were used to determine crucial predictors and to investigate the interactions between the factors. This research has shown that improved ergonomics factors will lead to better working conditions and thus increased job satisfaction. The observed ergonomic differences of these two production lines are compared, and appropriate managerial remedial action is recommended. The interventions to both the lines should reduce accident rates, minimize waste of resources, improve work effectiveness, and provide a better working environment that enhances employees' morale and maximizes productivity and profits. © 2010 Wiley Periodicals, Inc.     

Probabilistic analysis of a grouping algorithm

We study thegrouping by swapping problem, which occurs in memory compaction and in computing the exponential of a matrix. In this problem we are given a sequence ofn numbers drawn from {0,1, 2,...,m?1} with repetitions allowed; we are to rearrange them, using as few swaps of adjacent elements as possible, into an order such that all the like numbers are grouped together. It is known that this problem is NP-hard. We present a probabilistic analysis of a grouping algorithm calledMEDIAN that works by sorting the numbers in the sequence according to their median positions. Our results show that the expected behavior ofMEDIAN is within 10% of optimal and is asymptotically optimal asn/m→∞ or asn/m→0.     

Generalized Adjusted Rand Indices for cluster ensembles

In this paper, Adjusted Rand Index (ARI) is generalized to two new measures based on matrix comparison: (i) Adjusted Rand Index between a similarity matrix and a cluster partition (ARImp), to evaluate the consistency of a set of clustering solutions with their corresponding consensus matrix in a cluster ensemble, and (ii) Adjusted Rand Index between similarity matrices (ARImm), to evaluate the consistency between two similarity matrices. Desirable properties of ARI are preserved in the two new measures, and new properties are discussed. These properties include: (i) detection of uncorrelatedness; (ii) computation of ARImp/ARImm in a distributed environment; and (iii) characterization of the degree of uncertainty of a consensus matrix. All of these properties are investigated from both the perspectives of theoretical analysis and experimental validation. We have also performed a number of experiments to show the usefulness and effectiveness of the two proposed measures in practical applications.     

Informatics challenges of high-throughput microscopy

In this article, we discussed the emerging informatics issues of high-throughput screening (HTS) using automated fluorescence microscopy technology, otherwise known as high-content screening (HCS) in the pharmaceutical industry. Optimal methods of scoring biomarkers and identifying candidate hits have been actively studied in academia and industry, with the exception of data modeling topics. To find candidate hits, we need to score the images associated with different compound interventions. In the application example of RNAi genome-wide screening, we aim to find the candidate effectors or genes which correspond to the images acquired using the three channels. Scoring the effectors is equivalent to scoring the images based on the number of phenotypes existing in those images. Our ultimate objective of studying HTS is to model the relationship between gene networks and cellular phenotypes, investigate cellular communication via protein interaction, and study the disease mechanism beyond the prediction based on the molecular structure of the compound. Finally, computational image analysis has become a powerful tool in cellular and molecular biology studies. Signal processing and modeling for high-throughput image screening is an emerging filed that requires novel algorithms for dynamical system analysis, image processing, and statistical modeling. We hope that this article will motivate the signal processing communities to address challenging data modeling and other informatics issues of HTS.     

Simultaneous all-optical inverted and noninverted wavelength conversion using a single-stage fiber-optical parametric amplifier

We have demonstrated, for the first time to our knowledge, simultaneous all-optical inverted and noninverted wavelength conversion by using a single-stage two-pump fiber-optical parametric amplifier with an extinction ratio between 7 and 14 dB over 24 nm.     

Evaluation of a Computer-Assisted, 2-D Virtual Reality System for Training People With Intellectual Disabilities on How to Shop.

Objective: To evaluate the effectiveness of a 2-D virtual reality (VR) program for training people with intellectual disabilities to shop. Study Design: Pretest and posttest quasi-experimental design. Participants: Sixteen persons with intellectual disabilities (age 17-23 years; IQ = 40-54). Intervention: A VR program or a conventional program training them in supermarket-shopping skills. Main Outcome Measure: Checklist for supermarket-shopping skills. Results: Participants in both training groups showed significant improvement. There was no significant difference in effectiveness between the two methods. Conclusions: The VR program appears effective in training people with intellectual disabilities in an important community living skill. (PsycINFO Database Record (c) 2010 APA, all rights reserved)