Quality-of-service architecture: Monitoring and control ofmultimedia communications

For distributed multimedia applications the provision of system-wide quality of service (QoS) is essential. The quality-of-service architecture (QoS-A) developed at Lancaster University offers a framework to specify and implement the required performance properties of multimedia applications over integrated-service networks in a heterogeneous environment. The work addresses the problem of lower-level QoS as well as QoS support for multipeer multimedia applications operating in an open communication system. QoS filters have been developed to deal with the problems of heterogeneity in group communication environments. New challenges are also encountered in emerging mobile networks and user mobility; and recent developments in the Internet community highlight the need for appropriate QoS support mechanisms for multimedia applications. The paper describes how the QoS-A research at Lancaster University provides a flexible framework for the monitoring and control of multimedia communications across the broad range of computing systems and networks     

Filters: QoS support mechanisms for multipeer communications

The nature of distributed multimedia applications is such that they require multipeer communication support mechanisms. The multimedia traffic needs to be delivered to end-systems, networks, and end-users in a form that they can handle while satisfying the constraints imposed by the multimedia application. Quality-of-service (QoS) mechanisms that can ensure full quality media playout at high-performance workstations, while at the same time providing appropriately filtered lower quality media for playout at other end-systems, are required. Existing multicast support mechanisms are deficient for this purpose, in a heterogeneous environment, because they work on a common denominator premise where the quality delivered depends on the least capable link or node involved in the multicast session. This paper begins by discussing video compression; it proposes and analyzes the use of filtering mechanisms as means of supporting disparate receiver capabilities and QoS requirements. The paper describes the implementation of a number of filtering mechanisms and highlights the communications architecture within which these mechanisms are built. This architecture constitutes a specific network topology and a new protocol family developed within a UNIX-like operating system     

Induced Protic Behaviour in Aprotonic Ionic Liquids by Anion Basicity for Efficient Carbon Dioxide Capture

The interactions between aprotonic tetrabutylphosphonium carboxylate ionic liquids (ILs), [P_{4 4 4 4}][C_nCOO] (n=1, 2 and 7), and water were investigated. The cation-anion interactions occur via the α-¹H on [P_{4 4 4 4}]⁺ and the carboxylate headgroup of the anion. Upon addition, H₂O localises around the carboxylate headgroups, inducing an electron inductive effect towards the oxygens, leading to ion-pair separation. Studies with D₂O and [P_{4 4 4 4}][C_nCOO] revealed protic behaviour of the systems, with proton/deuterium exchange occurring at the α-¹H of the cation, promoted by the basicity of the anion, forming an intermediate ylide. The greater influence of van der Waals forces of the [P_{4 4 4 4}][C₇COO] system allows for re-orientation of the ions through larger interdigitation. The protic behaviour of the neat ILs allows for CO₂ to be chemically absorbed on the ylide intermediate, forming a phosphonium-carboxylate zwitterion, signifying proton exchange occurs even in the absence of H₂O. The absorption of CO₂ in equimolar IL-H₂O mixtures forms a hydrogen carbonate, through a proposed reaction of the CO₂ with an intermediate hydroxide, and carboxylic acid.     

A Note on the Mackey topology of a von Neumann algebra

Some of the properties of the upper bound of the spectrum of a quasilinear eigenvalue problem, subject to a positivity requirement, are derived. It is shown that, as a function of the surface heat-transfer coefficient, this parameter is a continuous, monotonic increasing function and is bounded above.     

Exchange bias on epitaxial Ni films due to ultrathin NiO layer

Exchange anisotropy refers to the effect that an antiferromagnetic (AF) layer grown in contact with a ferromagnetic (FM) layer has on the magnetic response of the FM layer. The most notable changes in the FM hysteresis loop due to the surface exchange coupling are a coercivity enhanced over the value typically observed in films grown on a nonmagnetic substrate, and a shift in the hysteresis loop of the ferromagnet away from the zero field axis. A typical observation is that the thickness of the antiferromagnet needs to exceed a critical value before exchange bias is observed. Here we report on the exchange bias properties observed in an epitaxial Ni/NiO system where a thin NiO layer forms spontaneously and is observed after annealing epitaxial Ni films MBE grown on MgO substrates.     

Crystal and molecular structures of two polymorphs of 4-methyl-2-nitroacetanilide (MNA)

Journal of Chemical Crystallography - The crystal and molecular structure of white (MNA-1) and yellow (MNA-3) forms of 4-methyl-2-nitroacetanilide have been determined by X-ray diffraction...     

Arbitrary single primer amplification of trace DNA substrates yields sequence content profiles that are discriminatory and reproducible

Single primer amplification is shown to yield a DNA profile that is reproducible when based on the sequence content of the amplicons rather than on the pattern of length polymorphism. The sequence-based profile increases in reliability with increasing numbers of cycles of amplification. This process uses an arbitrarily chosen primer and a low initial annealing temperature in order to amplify sequences from the whole metagenome present in a sample that may contain only trace DNA, and a large number of cycles to select subsets of sequences based on variable amplification efficiency. Using arrays, we demonstrate the utility and limitations of this approach for profiling the large metagenomes typical of soils and the trace DNA present in drug seizures. We suggest that this type of profiling will be most effective once next-generation sequencing and advanced sequence analysis becomes routine.     

Crystal and molecular structure of an amber polymorph of 4-methyl-2-nitroacetanilide (MNA)

The crystal and molecular structure of a third polymorph of 4-methyl-2-nitroacetanilide has been determined by X-ray diffraction. It crystallizes in the monoclinic system, space groupP2₁/c,Z=4,a=10.158(2),b=11.635(2),c=8.041(2) Å and=94.55(2)°. Using 1027 unique reflections, the structure was solved by the method of vector verification and refined by full-matrix least squares, which gave convergence toR=0.080. The structure consists of nearly planar molecules, all approximately parallel to one another with their longitudinal axes parallel tob. The amide group forms an intramolecular hydrogen bond with the nitro group. Molecules related byc-glide are stacked alongc in a very distinct columnar form. The columns are held together by dipole-dipole interactions between close antiparallel carbonyl groups or between close antiparallel nitro groups.