Comprehensive interpretation of gel electrophoresis data

From temperature analysis of polyacrylamide gel electrophoresis data for rigid-rod DNA analytes, it is proposed that an entropic force term is responsible for the discrepancy between Ogston-Morris-Rodbard-Chrambach model predictions and experimental results. This entropic force originates from reduction of the orientational freedom of anisotropic analytes in small pores of polyacrylamide gels. Time-dependent fluorescence anisotropy decay measurements confirm that, even in the absence of an external field, orientation of anisotropic analytes is restricted in polyacrylamide gels. A new comprehensive model is proposed that takes this effect into consideration. Predictions based on this model are found to compare favorably with experimental data for linear and three-arm asymmetrically branched rigid-rod DNA analytes covering a broad range of molecular aspect ratios and sizes. A new length scale is also proposed for describing the effect of analyte topology on electrophoretic mobility. This length scale reduces to the analyte radius of gyration in the limiting cases of spherically symmetric and linear rigid-rod species. Based on these results, a general approach is proposed for interpreting gel electrophoresis data of charged analytes possessing simple and complex topologies.     

Influence of different carbon nanotubes on the electrical and mechanical properties of melt mixed poly(ether sulfone)-multi walled carbon nanotube composites

Commercial Udel® poly(ether sulfone) (PSU) was filled with three different commercially available multiwalled carbon nanotubes (MWCNTs) by small scale melt mixing. The MWCNTs were as grown NC 7000 and two of its derivatives prepared by ball milling treatment. One of them was unmodified (NC 3150); the other was amino modified (NC 3152). The main difference beside the reactivity was the reduced aspect ratio of NC 3150 and NC 3152 caused by ball milling process. All PSU/MWCNT composites with similar filler content were prepared under fixed processing conditions and comparative analysis of their electrical and mechanical properties were performed and were correlated with their microstructure, characterized by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). A non-uniform MWCNT dispersion was observed in all composites. The MWCNTs were present in form of agglomerates in the size of 10–60 μm whereas the deagglomerated part was homogeneously distributed in the PSU matrix. The differences in the agglomeration states correlate with the variations of properties between different PSU/MWCNT composites. The lowest electrical percolation threshold of 0.25–0.5 wt.% was observed for the shortened non-functionalized MWCNT composites and the highest for amine-modified MWCNT composites (ca. 1.5 wt.%). The tensile behavior of the three composites was only slightly altered with CNT loading as compared to the pure PSU. However, the elongation at break showed a reduction with MWCNT loading and the reduction was least for composite with best MWCNT dispersion.     

Observation of Resistive Switching Memory by Reducing Device Size in a New Cr/CrO x /TiO x /TiN Structure

Nano-Micro Letters - The resistive switching memory characteristics of 100 randomly measured devices were observed by reducing device size in a Cr/CrO x /TiO x /TiN structure for the first time....     

Robust stability and performance analysis for uncertain linear systems—The distance measure approach

This paper presents readily applicable distance measures, robust stability margins and associated robust stability and robust performance theorems for three commonly used uncertainty structures (additive, input/output multiplicative, output/input inverse multiplicative). Besides providing robust stability results for a larger uncertainty class than previously reported (???_∞ instead of ???_∞), this paper also states robust performance theorems for the above uncertainty structures. In contrast to previous methods for robust performance analysis, they only require the computation of two infinity norms for every uncertain plant considered. The theorems in this paper enable practising engineers to choose the most suitable uncertainty structure for a family of uncertain plants, as illustrated through a physically motivated numerical example. Copyright © 2011 John Wiley & Sons, Ltd.     

H-NMRU: An Efficient Cache Replacement Policy with Low Area

In present multi-core devices, the individual processors do not need to operate at the highest possible frequencies. Instead there is a need to reduce the power, complexity and area of individual processor components like caches. In this paper we propose a low area, high performance cache replacement policy for embedded processors called Hierarchical Non-Most-Recently-Used (H-NMRU). The H-NMRU is a parameterizable policy where we can trade-off performance with area. We extended the Dinero cache simulator with the H-NMRU policy and performed architectural exploration with a set of cellular and multimedia benchmarks. On a 16 way cache, a two level H-NMRU policy where the first and second levels have 8 and 2 branches, respectively, performs as good as the Pseudo-LRU policy with storage area saving of 27%. Compared to true LRU, H-NMRU on a 16 way cache saves huge amount of area (82%) with marginal increase of cache misses (3%). Similar result was also noticed on other cache like structures like branch target buffers. Therefore, the two level H-NMRU cache replacement policy (with associativity/2 and 2 branches on the two levels) is a very attractive option for caches on embedded processors with associativities greater than 4. We present a case-study where it can be used on the L2 cache with substantial gain in performance and area for single and dual core platforms.     

Cytotoxicity and cellular uptake of tri-block copolymer nanoparticles with different size and surface characteristics

Particulate matter (PM) pollution is responsible for hundreds of thousands of deaths worldwide, the majority due to cardiovascular disease (CVD). While many potential pathophysiological mechanisms have been proposed, there is not yet a consensus as to which are most important in causing pollution-related morbidity/mortality. Nor is there consensus regarding which specific types of PM are most likely to affect public health in this regard. One toxicological mechanism linking exposure to airborne PM with CVD outcomes is oxidative stress, a contributor to the development of CVD risk factors including atherosclerosis. Recent work suggests that accelerated shortening of telomeres and, thus, early senescence of cells may be an important pathway by which oxidative stress may accelerate biological aging and the resultant development of age-related morbidity. This pathway may explain a significant proportion of PM-related adverse health outcomes, since shortened telomeres accelerate the progression of many diseases. There is limited but consistent evidence that vehicular emissions produce oxidative stress in humans. Given that oxidative stress is associated with accelerated erosion of telomeres, and that shortened telomeres are linked with acceleration of biological ageing and greater incidence of various age-related pathology, including CVD, it is hypothesized that associations noted between certain pollution types and sources and oxidative stress may reflect a mechanism by which these pollutants result in CVD-related morbidity and mortality, namely accelerated aging via enhanced erosion of telomeres. This paper reviews the literature providing links among oxidative stress, accelerated erosion of telomeres, CVD, and specific sources and types of air pollutants. If certain PM species/sources might be responsible for adverse health outcomes via the proposed mechanism, perhaps the pathway to reducing mortality/morbidity from PM would become clearer. Not only would pollution reduction imperatives be more focused, but interventions which could reduce oxidative stress would become all the more important.     

Cognitive vertical handover engine for vehicular communication

Always best connected (ABC) communication is an essential requirement for intelligent transportation system. In this paper, we propose a cognitive vertical handover (CVHO) engine to ensure seamless connectivity on the move. Analytic hierarchy process and artificial neural network are used for the development of the algorithm and MATLAB is used as simulation platform. The CVHO engine, which is knowledge based context aware system, takes into account multiple relevant criteria and previous experiences. This system is capable of performing both voluntary and reflex actions. A detailed literature review is presented to compare this work with the conventional methods of vertical handover. A case study, considering the network selection in a typical highway traffic scenario, which consists of both peer-to-peer (P2P) and mobile networks, is presented for the validation of the design. Three radio access technologies, WLAN (P2P), UMTS and WiMAX (mobile networks), are considered for simulation. The results show that the presented model not only realistically optimizes the best available network on the move but also avoids unnecessary handovers. This algorithm is specific to vehicular communication system and hence variation in network selection with vehicle speed is shown.     

Stability analysis and controller design for Lur'e system with hysteresis nonlinearities: a negative-imaginary theory based approach

In this paper, absolute stability condition is investigated when a hysteresis nonlinearity is connected to a linear subsystem via positive feedback in Lur'e system framework. In particular, the nonlinearity is considered to belong to the time-invariant slope-restricted counter-clockwise hysteresis class. An absolute stability criterion is proposed in terms of the negative-imaginary system properties. In effect, the stability condition requires the linear subsystem to belong to the strongly strict negative-imaginary (SSNI) system class along with satisfying a matrix condition involving the DC-gain of the linear subsystem and the slope-upper-bounds of the nonlinearities. Compliance to the conditions guarantees asymptotic convergence of state-trajectories to an equilibrium set. Invoking the stability result and exploiting the relaxed minimality assumption of SSNI systems, a static state-feedback synthesis method is proposed to ensure absolute stability for such hysteretic systems. Tractable conditions in the form of linear matrix inequalities can be solved to obtain a stabilising state-feedback gain matrix. Finally, a numerical example of multi-input–multi-output system is presented to illustrate the usefulness of the proposed results.     

A Layered Finite Element Method for Electromagnetic Analysis of Large-Scale High-Frequency Integrated Circuits

A high-capacity electromagnetic solution, layered finite element method, is proposed for high-frequency modeling of large-scale three-dimensional on-chip circuits. In this method, first, the matrix system of the original 3-D problem is reduced to that of 2-D layers. Second, the matrix system of 2-D layers is further reduced to that of a single layer. Third, an algorithm of logarithmic complexity is proposed to further speed up the analysis. In addition, an excitation and extraction technique is developed to limit the field unknowns needed for the final circuit extraction to a single layer only, as well as keep the right-hand side intact during the matrix reduction process. The entire procedure is numerically rigorous without making any theoretical approximation. The computational complexity only involves solving a single layer irrespective of the original problem size. Hence, the proposed method is equipped with a high capacity to solve large-scale IC problems. The proposed method was used to simulate a set of large-scale interconnect structures that were fabricated on a test chip using conventional Si processing techniques. Excellent agreement with the measured data has been observed from dc to 50 GHz