High-throughput double quantitative competitive polymerase chain reaction for determination of genetically modified organisms

Quantitative competitive polymerase chain reaction (PCR), especially the double competitive PCR methods (DC-PCR), have evolved as reliable approaches to quantification of genetically modified organisms (GMO) in food. However, DC-PCR is a low-throughput method because it requires titration of each sample with various amounts of a competitive internal standard, a protocol that involves several PCRs per sample followed by electrophoresis and densitometry. To address this drawback, we have developed a new method for GMO quantification, namely, a high-throughput double quantitative competitive PCR (HT-DCPCR). In HT-DCPCR, electrophoresis and densitometry are replaced by a rapid, microtiter well-based bioluminometric hybridization assay and there is no need for titration of each sample. The determination of GM soya was chosen as a model. We have constructed internal standards (DNA competitors) both for the 35S promoter sequence and for a plant-specific reference gene (lectin). The competitors have identical size and share the same primer binding sites with the target sequences but differ in a 24-bp internal segment. Each target sequence (35S and lectin) is coamplified with a constant amount (1000 copies) of the respective competitor. The four amplified fragments are hybridized with specific probes and captured on a universal solid phase to achieve simplicity and high throughput. The hybrids are determined by using streptavidin conjugated to the photoprotein aequorin. The ratio of the luminescence values obtained for the target and the competitor is linearly related to the starting amount of target DNA. The limit of quantification for the 35S promoter is 24 copies. The proposed method was evaluated by determining the GMO content of soybean powder certified reference materials. Also HT-DCPCR was compared to real-time PCR in a variety of real samples.     

Multiple roller bearing-shaft systems

A design method for shaft and roller bearing systems is described, in which shaft flexure causes the loads on the rollers to be no longer purely radial. The resulting pressure distributions on the rollers are predicted without recourse to any assumptions relating to plain strain.Some experimental results are also presented, confirming the accuracy of the theory.     

Towards a more effective and reliable salt crystallization test for porous building materials: state of the art

The durability of building materials with respect to salt crystallization is commonly determined by accelerated weathering tests, carried out in the laboratory. An effective laboratory weathering test should assess the durability and, in the case of conservation of historic buildings, the compatibility of repair materials with those existing. Besides, the test should provide reliable results within a reasonable period of time, accelerating the deterioration process without however altering its mechanism. Despite several national and international standards, recommendations and guidelines, a commonly accepted testing protocol does not yet exist. Researchers often develop and apply their own procedure, a fact that complicates comparison between different studies. The RILEM Technical Committee 271 ASC has been set up with the scope of developing improved test procedures for the assessment of the behaviour of materials under the influence of salt crystallization, which should overcome the limitations of existing standards and recommendations. This paper constitutes one of the first results of the work of the Technical Committee. It critically reviews the literature on salt crystallization tests, identifies advantages and limitations of the several test protocols and provides new ideas for the development of improved salt crystallization procedures.     

HKMG CMOS technology qualification: The PBTI reliability challenge

We present a brief overview of Positive Bias Temperature Instability (PBTI) commonly observed in n-channel MOSFETs with SiO₂/HfO₂/TiN dual-layer gate stacks when stressed with positive gate voltage at elevated temperatures. We review the origin and present understanding of the characteristics of oxide traps that are responsible for the complex behavior of threshold voltage stability. We discuss the various physical mechanisms that are believed to govern the transient charging and discharging of these traps as the backbone of the models that have been proposed for PBTI degradation and recovery. Next we review the state-of-the-art in PBTI characterization and we present some of the key stress results on both the device as well the circuit level. Special emphasis is given on the open PBTI issues that need to be carefully addressed for a robust reliability methodology that accurately predicts PBTI lifetimes. Finally we mention some of the gate stack scaling effects on PBTI.     

A highly segmented NaI(Tl) detector with vacuum photodiode readout for measuring electromagnetic showers at the CERN ISR

In this report we describe construction and performance of two identical units of electromagnetic shower counters which were installed in the axial-field spectrometer at the CERN-ISR in 1982 to provide improved detection of photons and electrons over a 1.3 sr solid angle of the AFS calorimeter. Thallium doped sodium-iodide in the form of small blocks served as an active shower material. Vacuum photodiodes and low-noise charge sensitive electronics were used for the deposited energy measurement and signal amplification. The stable performance of the detectors over a period of more than 18 months until the closure of the ISR has proven that vacuum photodiodes can reliably be utilized in highly modularized large scale detectors operating in a high magnetic field environment.     

Autonomous intelligent cruise control

Vehicle following and its effects on traffic flow has been an active area of research. Human driving involves reaction times, delays, and human errors that affect traffic flow adversely. One way to eliminate human errors and delays in vehicle following is to replace the human driver with a computer control system and sensors. The purpose of this paper is to develop an autonomous intelligent cruise control (AICC) system for automatic vehicle following, examine its effect on traffic flow, and compare its performance with that of the human driver models. The AICC system developed is not cooperative; i.e., it does not exchange information with other vehicles and yet is not susceptible to oscillations and “slinky” effects. The elimination of the “slinky” effect is achieved by using a safety distance separation rule that is proportional to the vehicle velocity (constant time headway) and by designing the control system appropriately. The performance of the AICC system is found to be superior to that of the human driver models considered. It has a faster and better transient response that leads to a much smoother and faster traffic flow. Computer simulations are used to study the performance of the proposed AICC system and analyze vehicle following in a single lane, without passing, under manual and automatic control. In addition, several emergency situations that include emergency stopping and cut-in cases were simulated. The simulation results demonstrate the effectiveness of the AICC system and its potentially beneficial effects on traffic flow     

Model reference adaptive control for plants with unknown relativedegree

A parameterization scheme for model reference control which guarantees stable model-plant transfer function matching is presented. This scheme has a linear dynamic feedforward block whose numerator and denominator should be stable polynomials for closed-loop stability. An adaptive law is designed to update the controller parameters in the feedback loop and the coefficients of the numerator of the feedforward block as well as some additional parameters. Since, for stability, the inverse of the polynomial differential operator defined by some of the estimated parameters has to be stable, the adaptive law is modified using a projection technique. The stability analysis of the model reference adaptive control (MRAC) scheme is given. The robustness of the MRAC scheme with respect to unmodeled dynamics is established     

Frequency domain conditions for strictly positive real functions

Frequency domain conditions for strictly positive real (SPR) functions which appear in literature are often only necessary or only sufficient. This point is raised in [1], [2], where necessary and sufficient conditions in thes-domain are given for a transfer function to be SPR. In this note, the points raised in [1], I2] are clarified further by giving necessary and sufficient conditions in the frequency domain for transfer functions to be SPR. These frequency-domain conditions are easier to test than those given in thes-domain or time domain [1], [2].     

The fuzzy set theory: a helpful tool for the estimation of sensory properties of crusting sausage appearance by a single expert

Automation of visual assessment of foods is a desirable target in quality assurance. We propose an approach based on the theory of fuzzy sets to reproduce, with the help of a camera, the evaluation of sensory properties of a crusting sausage, made close to the manufacturing line (at-line), by a single expert evaluation: the operator. Our study is applied to the assessment of a sausage defect: the crusting. By means of a camera and an adapted image processing, the human evaluation of crusting is reproduced. Good results have been obtained from a database of 76 images.