A review of current PCR-based methodologies for the authentication of meats from game animal species

The authenticity of food is currently a major issue for researchers, consumers, industries and policy markers at all levels of the production process. Particularly in the meat industry, products from game animals are susceptible targets for fraudulent labeling due to the economic profit that results from selling cheaper meat as meat from more profitable and desirable species. A part from meat species adulteration, illegal poaching of endangered game species may take place contributing to threat of wildlife populations. These reasons have encouraged the development of methods to ensure fair trade and labeling of game meats from production level to consumer use of end products. In the last years, full attention has been turning towards implementation of molecular genetic approaches for meat species identification because of their high sensitivity and specificity, as well as rapid processing time and low cost. This work presents an overview of the main PCR-based techniques applied to date to verify the authenticity of meat and meat products from game species.     

The posterior predictive p-value for the problem of goodness of fit

The aim of this paper is to explore some features and possible uses of the posterior predictivep-value for the problem of goodness of fit. First, the behaviour of the posterior predictivep-value is compared with the behaviour of the classicalp-value through some interesting examples. Then, we consider a decision problem for simultaneously deciding to accept/reject a modelM and to accept/reject a null hypothesis (if we have accepted the modelM); the posterior predictivep-value is used for estimating the posterior probability of the model. Research partially supported by DGESIC (Spain) under grant number PB97-0021.     

Systematic Width-and-Length Dependent CMOS Transistor Mismatch Characterization and Simulation

This paper presents a methodology for characterizing the random component of transistor mismatch in CMOS technologies. The methodology is based on the design of a special purpose chip which allows automatic characterization of arrays of NMOS and PMOS transistors of different sizes. Up to 30 different transistor sizes were implemented in the same chip, with varying transistors width W and length L. A simple strong inversion large signal transistor model is considered, and a new five parameters MOS mismatch model is introduced. The current mismatch between two identical transistors is characterized by the mismatch in their respective current gain factors /, V _TO threshold voltages , bulk threshold parameters , and two components for the mobility degradation parameter mismatch ₀ and _e. These two components modulate the mismatch contribution differently, depending on whether the transistors are biased in ohmic or in saturation region. Using this five parameter mismatch model, an extraordinary fit between experimental and computed mismatch is obtained, including minimum length (1 m) transistors for both ohmic and saturation regions. Standard deviations for these five parameters are obtained as well as their respective correlation coefficients, and are fitted to two dimensional surfaces f(W, L) so that their values can be predicted as a function of transistor sizes. These functions are used in an electrical circuit simulator (Hspice) to predict transistor mismatch. Measured and simulated data are in excellent agreement.     

Steric-hyperlayer sedimentation field flow fractionation and flow cytometry analysis applied to the study of Saccharomyces cerevisiae

Sedimentation field flow fractionation separation associated with flow cytometry has been used for the characterization of several commercial Saccharomyces cerevisiae yeasts used for wine production. A new type of channel 80 microm thick and new operating conditions, such as sample introduction when field and flow are established and a channel inlet connected to the accumulation wall, were used. Good repeatability (5% RSD) and reduced analysis time (2-10 min) were obtained. The avoidance of the stop-flow relaxation process in conjunction with the use of a channel of reduced thickness has demonstrated that an effective "steric-hyperlayer" mode driving to a major focusing effect of the species in the channel thickness is involved in the elution of the yeast cells. Flow cytometry analyses were performed, and the forward scattering and side scattering yeast characteristics correlation maps were obtained. Field flow fractionation and flow cytometry information obtained indicated that the fractogram profiles of the yeast cell depended not only on the size, but also on the shape and density.     

Understanding multilayers from a geometrical viewpoint

We reelaborate on the basic properties of lossless multilayers. We show that the transfer matrices for these multilayers have essentially the same algebraic properties as the Lorentz group SO(2, 1) in a (2 + 1)-dimensional space-time as well as the group SL(2, R) underlying the structure of the ABCD law in geometrical optics. By resorting to the Iwasawa decomposition, we represent the action of any multilayer as the product of three matrices of simple interpretation. This group-theoretical structure allows us to introduce bilinear transformations in the complex plane. The concept of multilayer transfer function naturally emerges, and its corresponding properties in the unit disk are studied. We show that the Iwasawa decomposition is reflected at this geometrical level in three simple actions that can be considered the basic pieces for a deeper understanding of the multilayer behavior. We use the method to analyze in detail a simple practical example.     

The “18 Year” Alternative: A Business Proposal to Develop Commercial Fusion Energy by 2021—The Fusion Power Corporation

This policy essay asserts that the 35 year plan recently adopted by the U.S. Department of Energy's Fusion Energy Sciences Advisory Committee is too risk averse and too costly. An alternative 18 year schedule is proposed. All dollar amounts shown below are undiscounted, and are only intended to be indicative of approximate future costs.     

Color Segmentation Applied to Study of the Angiogenesis. Part I

The aim of this work is the color image segmentation of blood vessels in the angiogenesis process. With the purpose of comparison we carried out some experiments using different methods and in different color spaces, arriving to the final conclusion that the best results are obtained, according to our application, in the RGB space. We performed a number of researches in the red, green and blue channels and we propose an alternative strategy that is, working in a single channel. The segmentation task can be decomposed into two stages. First, selections of color space, and second, selection of channel of major information and finally segmentation process. Our results were compared with manual segmentation realized by an expert, where difference errors of less than 4% were observed. It is demonstrated by extensive experimentation, using real image data, that proposed strategy is fast and adequate in the environment of a personal computer. These images will be subject to a further morphometrical analysis, in order to diagnose and prognosticate automatically malign tumors.     

Hardware modifications to an isotope ratio mass spectrometer continuous-flow interface yielding improved signal, resolution, and maintenance

A home-built combustion interface was constructed to improve signal, resolution, and maintenance of a continuous-flow gas isotope ratio system. Chromatographic peak shapes were preserved by minimizing changes in tubing diameter and dead volumes. A single piece of fused silica capillary was used to connect the gas chromatograph (GC) to the isotope ratio mass spectrometer (IRMS), thus eliminating extraneous combustion furnace and water trap fittings. Analysis of a standard mixture of hydrocarbons yielded a 2-fold increase in signal over a slightly modified conventional system. Column efficiency, expressed as trennzahl (TZ), improved significantly (Student's t-test 95% CI) by an average factor of 1.4 for replicates analyzed under similar conditions. The design is robust, requires less maintenance, and reduces leaks because the number of connections is minimized. Benefits of this system are transferable to virtually all commercially available continuous-flow systems.