On Burst Length Distribution and Preemption Probabilities in OBS Networks with Burst Segmentation

Recently, preemption techniques have attracted considerable attention as a means to provide differentiated quality of service in optical burst switching (OBS) networks. This paper is focused on the analysis of preemption probabilities for bursts within the same priority class. As proposed by Vokkarane and Jue ((2003)* IEEE J Select Areas Commun 21(7): 1198–1209) an incoming burst will preempt the burst in service, within the same priority class, if the residual length of the burst in service is smaller than the incoming burst length. For a general case with wavelength conversion, the preemption probability of contending bursts with a generic service distribution, not necessarily exponential, is analyzed. First, we show that the size distribution for the preempting bursts is shifted to larger values, in comparison to the original burst size distribution. Second, we obtain an upper and lower bound for the preemption probability. Finally, the asymptotic behavior of the OBS switch is analyzed showing that preemption will always occur for a very large number of wavelengths.     

Mammary gland expression of transgenes and the potential for altering the properties of milk

Transgenic animals are a useful in vivo experimental model for assessing the ability and impact of foreign gene expression in a biological system. Transgenic mice are most commonly used, while transgenic sheep, goats, pigs and cows have also been developed for specific, "applied" purposes. Most of the work directed at targeting expression of transgenes to the mammary gland of an animal, by using a milk gene promoter, has been with the intent of either studying promoter function or recovering the desired protein from the milk. Transgenic technology can also be used to alter the functional and physical properties of milk resulting in novel manufacturing properties. The properties of milk have been altered by adding a new protein with the aim of improving the milk, not of recovering the protein for other uses.     

Packet Video Broadcasting with General-Purpose Operating Systems in an Ethernet

Video transmission with general-purpose PCs poses a number of requirements that radically differ from those of high-end dedicated video servers. We analyze the scenario of an Ethernet local area network in which a number of PCs are transmitting video streams, while other TCP/IP applications are also running concurrently. Our findings show that since the operating system clock resolution cannot cope with the transmission timing requirements the following holds: if the video transmission is performed with exact timing accuracy to maintain a constant rate then CPU load grows to 100%, thus blocking the PC for other user applications; on the other hand, if transmission is performed in a bursty manner, i.e. with sleep system calls, then CPU load decreases dramatically but the increased burstiness of the video stream has a negative impact on network performance (for example, capture effect in the Ethernet). Furthermore, the impact of video transmission over the rest of TCP/IP applications running on the same network depends heavily on the packet size. We provide an integrated analysis of operating system and network parameters to achieve video broadcasting while preserving timing requirements and minimizing the impact on other applications.     

Comparative study of the morphological degradation in nickel thin films exposed to H<Subscript>2</Subscript>S media and deposited by magnetron sputtering and electrolytic process

Nickel thin films with regular configuration and similar thickness were deposited on steel AISI 1018 (UNSG 10180) by two different techniques: magnetron sputtering and electrolytic process. The main aim of this work is to compare the surfaces deposited films made by the two techniques using the scanning electronic microscopy and to identify their morphological differences and imperfections. We evaluate the protective coatings properties when the films are in contact with an acid medium. We also study the thin films coatings by the spectroscopy impedance technique. We obtain that the sputtering deposits present a homogeneous thin film coating that is better than the one obtained by the electrolytic technique. It is expected that the thin film coatings made in this work can protect the steel against corrosion when it is in contact with an acid environment.     

Signal Space Diversity Augmented Space Time Block Coded Communication System

In this paper we propose the combination of space-time diversity techniques and signal space diversity, in order to improve communication system performance. Specifically, we use prior knowledge of the channel behavior to design a mapping algorithm to generate a two-dimensional constellation with the same number of symbols as MPSK constellations currently used in coherent space time block coding applications, to demonstrate that superior performance can be achieved. This is accomplished by constructing a two-dimensional map that results from the minimization of the estimated symbol error probability when transmission occurs in a fading environment. System performance for each each mapping is assessed in quasi-static Rayleigh fading channels.     

On the non-linear Maxwell–Cattaneo equation with non-constant diffusivity: Shock and discontinuity waves

A numerical study on a non-linear hyperbolic diffusion equation is proposed. The Hartree hybrid method combining finite difference techniques with the method of characteristics is used in the presence of discontinuities between initial and boundary conditions. The technique proved to be an useful tool to overcome oscillation problems and spurious solutions in case of strong non-linearities related to both attractive or repulsive interactions between diffusing species. Two different expressions for the diffusion coefficient are used in order to compare our results with the ones obtained in previous studies relying upon the Laplace transform technique and the MacCormack predictor–corrector method. Finally, an analytic approach based on the singular surface theory is proposed to motivate the numerical results and to clarify some controversial aspects concerning the penetration depth of a diffusive front in the presence of interactions.     

Dual mode of interaction of DNA polymerase epsilon with proliferating cell nuclear antigen in primer binding and DNA synthesis

An extension to current maximum-likelihood variance-components procedures for mapping quantitative-trait loci in sib pairs that allows a simultaneous test of allelic association is proposed. The method involves modeling of the allelic means for a test of association, with simultaneous modeling of the sib-pair covariance structure for a test of linkage. By partitioning of the mean effect of a locus into between- and within-sibship components, the method controls for spurious associations due to population stratification and admixture. The power and efficacy of the method are illustrated through simulation of various models of both real and spurious association.     

Process Control System Synthesis under Constraints Imposed on Controlled Variables

The Principal Components Regression method is adapted for automatic process control synthesis. The modified method ensures that the constraints imposed on the controlled variables are satisfied as the control and disturbing actions vary randomly. Conventional methods of compressing information into a space of a lower dimensionality are adapted for constrained controlled variables. A simple numerical example is provided to illustrate the synthesis of a linear control system for a given model process.     

Identification of key volatiles responsible for odour quality differences in popped popcorn of selected hybrids

Volatile compounds from six hot-air-popped popcorn hybrids, being also classified into three types, were evaluated by a gas chromatograph equipped with a mass spectrometer (GC/MS). In addition, 68 panelists determined odour quality differences of the popped kernels by an aroma ranking test. Total number of volatiles detected by GC/MS were 195, of which 51 peaks were positively identified, 92 peaks were tentatively identified, and 52 peaks were unidentified. The relationships between quality/quantity of volatiles and sensory results revealed that 2-acetylpyridine was considered to contribute to the overall popped popcorn aroma quality favorably or not adversely. However, 2,5-dimethylpyrazine, (E,E)-2,4-decadienal, 2-methylpyrazine, ethylpyrazine, 2-ethyl-5-methylpyrazine and 3-ethyl-2, 5-dimethylpyrazine were found to be important popcorn volatiles, but to contribute negatively to characteristic popped popcorn odour. Numerous other volatiles such as 2-furfurylthiol (2-furanmethanthiol), pyrrole, 3-(methylthio)propanal (methional), 3-furaldehyde, 4-vinyl-2-methoxyphenol (4-vinylguaiacol), 2-pentylfuran, 2-furanmethanol (furfuryl alcohol), hexanal, 1-pentanol, 2-methyl-5-vinylpyrazine, 2-methoxyphenol (guaiacol), 2-acetylpyrrole and others may be responsible in part of typical popcorn aroma characteristics.