A non-antibacterial oxazolidinone derivative that inhibits epithelial cell sheet migration

We have developed a high-throughput assay for screening chemical libraries for compounds that affect cell sheet migration during wound closure in epithelial cell monolayers. By using this assay, we have discovered a new inhibitor of cell sheet migration. This compound (UIC-1005) is a 3,4-disubstituted oxazolidinone that bears an electrophilic alpha,beta-unsaturated N-acyl group required for activity. UIC-1005 also inhibits growth in an epithelial cell proliferation assay. The molecule does not display general toxicity at concentrations at which it potently inhibits cell sheet migration and growth. Unlike certain 3,5-disubstituted oxazolidinones, it exhibits no antibacterial activity. UIC-1005 therefore represents a new class of bioactive oxazolidinone derivative that may prove useful as a probe for signaling pathways leading to cell motility.     

Effect of channel geometry on solute dispersion in pressure-driven microfluidic systems

Pressure-driven transport of fluid and solute samples is often desirable in microfluidic devices, particularly where sufficient electroosmotic flow rates cannot be realized or the use of an electric field is restricted. Unfortunately, this mode of actuation also leads to hydrodynamic dispersion due to the inherent fluid shear in the system. While such dispersivity is known to scale with the square of the Peclet number based on the narrower dimension of the conduit (often the channel depth), the proportionality constant can vary significantly depending on its actual cross section. In this article, we review previous studies to understand the effect of commonly microfabricated channel cross sections on the Taylor–Aris dispersion of solute slugs in simple pressure-driven flow systems. We also analyze some recently proposed optimum designs which can reduce the contribution to this band broadening arising from the presence of the channel sidewalls. Finally, new simulation results have been presented in the last section of this paper which describe solutal spreading due to bowing of microchannels that can occur from stresses developed during their fabrication or operation under high-pressure conditions.     

Score normalization in multimodal biometric systems

Multimodal biometric systems consolidate the evidence presented by multiple biometric sources and typically provide better recognition performance compared to systems based on a single biometric modality. Although information fusion in a multimodal system can be performed at various levels, integration at the matching score level is the most common approach due to the ease in accessing and combining the scores generated by different matchers. Since the matching scores output by the various modalities are heterogeneous, score normalization is needed to transform these scores into a common domain, prior to combining them. In this paper, we have studied the performance of different normalization techniques and fusion rules in the context of a multimodal biometric system based on the face, fingerprint and hand-geometry traits of a user. Experiments conducted on a database of 100 users indicate that the application of min–max, z-score, and tanh normalization schemes followed by a simple sum of scores fusion method results in better recognition performance compared to other methods. However, experiments also reveal that the min–max and z-score normalization techniques are sensitive to outliers in the data, highlighting the need for a robust and efficient normalization procedure like the tanh normalization. It was also observed that multimodal systems utilizing user-specific weights perform better compared to systems that assign the same set of weights to the multiple biometric traits of all users.     

Intelligent agents in electronic markets for information goods: customization, preference revelation and pricing

Electronic commerce has enabled the use of intelligent agent technologies that can evaluate buyers, customize products, and price in real-time. Our model of an electronic market with customizable products analyzes the pricing, profitability and welfare implications of agent-based technologies that price dynamically based on product preference information revealed by consumers. We find that in making the trade-off between better prices and better customization, consumers invariably choose less-than-ideal products. Furthermore, this trade-off has a higher impact on buyers on the higher end of the market and causes a transfer of consumer surplus towards buyers with a lower willingness to pay. As buyers adjust their product choices in response to better demand agent technologies, seller revenues decrease since the gains from better buyer information are dominated by the lowering of the total value created from the transactions. We study the strategic and welfare implications of these findings, and discuss managerial and technology development guidelines.     

Sol-Gel-Derived Soda Lime-High Silica Glass

Sols containing well-mixed tetraethyl orthosilicate, sodium methylate (CH₃ONa), and Ca metal dissolved in HCIO₄ were hydrolyzed at low pH. After gelation, controlled drying, and subsequent firing at 600°C, the mixture yielded clear glass chunks. Glasses containing 85% to <100% SiO₂, which otherwise are difficult to make by conventional melting techniques, could be made using this technique.     

Grain size estimation in anisotropic materials

The need for an efficient sampling technique for estimation of grain size in anisotropic materials is addressed through statistical analysis of quantitative metallographic data on a series of iron specimens cold rolled to different extents. The data are utilized to arrive at the most efficient procedure for measuring grain size in anisotropic materials. The analysis reveals that, for cold-rolled materials, design-based intersection counting on a single longitudinal metallographic plane is sufficient to reliably and efficiently estimate the average grain size.     

Resolution limits in signal recovery

Resolution analysis for the problem of signal recovery from finitely many linear measurements is the subject of this paper. The classical Rayleigh limit serves only as a lower bound on resolution since it does not assume any recovery strategy and is based only on observed data. We show that details finer than the Rayleigh limit can be recovered by simple linear processing that incorporates prior information. We first define a measure of resolution based on allowable levels of error that is more appropriate for current signal recovery strategies than the Rayleigh definition. In the practical situation in which only finitely many noisy observations are available, we have to restrict the class of signals in order to make the resolution measure meaningful. We consider the set of bandlimited and essentially timelimited signals since it describes most signals encountered in practice. For this set, we show how to precompute resolution limits from knowledge of measurement functionals, signal-to-noise ratio, passband, energy concentration regions, energy concentration factor, and a prescribed level of error tolerance. In the process, we also derive an algorithm for high-resolution signal recovery. We illustrate the results with examples in one and two dimensions     

Formation of M23C6 type carbides in heat-treated extra low carbon Mn-Si and Mn-Si-Nb high strength low alloy “mar” steels

Structural investigations in extra low carbon mar steels with nominal compositions A1 (4 Mn-1.0 Si), A2 (4 Mn-1.0 Si – 0.042 Nb), A3 (～ 5 Mn-1.5 Si), A4 (2.6 Mn-1.0 Si) and A5 (～ 5 Mn-2.5 Si) in the heat treated condition by X-ray diffraction technique (Debye-Scherrer method) for identifying strengthening mechanisms. Results on the formation of M₂₃C₆ type carbide either singly (in most cases) or in combination with austenite. Discussion pertaining to 1. identification of factors promoting the structural changes and, 2. their likely effect on mechanical properties.     

An amorphous silicon thin film transistor: Theory and experiment

The volt-ampere characteristics for a thin film transistor fabricated with vacuum deposited amorphous silicon as the semiconductor is presented. The substrate is single crystalline silicon with a 3000 Å layer of thermally grown silicon dioxide as the insulator. The gate is a buried N⁺ phosphorus diffused region while the source and drain contacts are interdigited fingers of aluminum. By using the Cohen-Fritzsche-Ovshinsky model for the density of localized states in the mobility gap, the V_G vs I_D characteristic at small values of V_D is predicted and experimentally verified. This characteristic is used to theoretically predict the family of I_D curves for the TFT over a range of V_G and V_D. The theory and experiment agree exceptionally well below the gate-drain pinch-off, thereby verifying the theory of a TFT with a uniform distribution of traps in the band-gap.     

Theory of back surface field silicon solar cells

Back surface field silicon solar cells with n⁺pp⁺ (or sometimes p⁺nn⁺) structures are found to have better characteristics than the conventional solar cells. The existing theories have not been able to satisfactorily predict the experimentally observed parameters on these cells. A theory, based on the transport of both minority and majority carriers under the charge neutrality condition, has been developed in the present paper which explains the behavior of the back surface field solar cells. Good agreement is achieved between the results obtained by using this theory and the experimental observations of earlier workers.