Spectrofluorimetric determination of magnesium in blood serium with calcein blue

Magnesium was determined in blood serum by fluorimetry with calcein blue (CB) in alkaline solution (0.01 M KOH). Four separate procedures for masking of iron, copper, zinc and calcium were applied. Complete masking was obtained with a mixture of ethylene glycol-O,O′-bis(2-aminoethyl)-N,N,N′,N′-tetraacetic acid, triethanolamine and triethylenetetramine. The mean value of magnesium in a 40-μl sample of quality control serum was within the appropriate limits of the reference sample. The effects of pH, masking agents and matrix of serum on the fluorescence of CB were investigated.     

Performance analysis of high-speed TCP protocols in LTE X2 handover under realistic operational conditions

Telecommunication Systems - Broadband mobile networks have rapidly evolved over the last years. The unique environment they operate, however, sets new challenges for the Transmission Control...     

Advanced MCMC methods for sampling on diffusion pathspace

The need to calibrate increasingly complex statistical models requires a persistent effort for further advances on available, computationally intensive Monte-Carlo methods. We study here an advanced version of familiar Markov-chain Monte-Carlo (MCMC) algorithms that sample from target distributions defined as change of measures from Gaussian laws on general Hilbert spaces. Such a model structure arises in several contexts: we focus here at the important class of statistical models driven by diffusion paths whence the Wiener process constitutes the reference Gaussian law. Particular emphasis is given on advanced Hybrid Monte-Carlo (HMC) which makes large, derivative-driven steps in the state space (in contrast with local-move Random-walk-type algorithms) with analytical and experimental results. We illustrate its computational advantages in various diffusion processes and observation regimes; examples include stochastic volatility and latent survival models. In contrast with their standard MCMC counterparts, the advanced versions have mesh-free mixing times, as these will not deteriorate upon refinement of the approximation of the inherently infinite-dimensional diffusion paths by finite-dimensional ones used in practice when applying the algorithms on a computer.     

Throughput Analysis of the Intermittent DCF for Opportunistic Spectrum Access

Recently, the opportunistic spectrum access (OSA) technologies have drawn a lot of the research community attention, because, by utilizing cognitive radio (CR) capabilities, they provide us with solutions to compensate for the spectrum underutilization. The MAC design is an important aspect of this on-going research. In this paper we study the performance of the distributed coordination function (DCF) in the OSA environment, which requires periodic intermissions to the MAC operation for spectrum scan procedures and opportunities identification. We present several modifications to the DCF that render it robust and operational in demanding environments of frequent spectrum scan procedures and low achievable transmission rates. We also present an analytical model for the throughput calculation of the resulted Intermittent DCF, which is based on the Bianchi’s Markov model and extends it so as to include the intermittent nature of the OSA environment. The proposed model is validated through simulations. A new parameter, controllable by the CR terminals, is used to optimize the throughput performance in realistic OSA scenarios. Using the presented analytical model we evaluate the performance of the Intermittent DCF under the effect of certain design parameters.     

Novel Functional Fullerene Materials: Fullerenes as Energy Acceptors

Summary.  Fullerene derivatives exhibit absorption throughout the UV/Vis region up to 750 nm. This feature is important for easy excitation. Once excited, fullerenes may become both electron and energy acceptors. The distinction between these two pathways depends strongly on the partner involved (donor) and on the conditions employed (solvent, etc.). Received June 23, 2000. Accepted July 7, 2000     

Methodology for measuring conformation of solvent-disrupted protein subunits using T-WAVE ion mobility MS: An investigation into eukaryotic initiation factors

The methodology developed in the research presented herein makes use of chaotropic solvents to gently dissociate subunits from an intact macromolecular complex and subsequently allows for the measurement of collision cross section (CCS) for both the recombinant (R-eIF3k) and solvent dissociated form of the subunit (S-eIF3k). In this particular case, the k subunit from the eukaryotic initiation factor 3 (eIF3) was investigated in detail. Experimental and theoretical CCS values show both the recombinant and solvent disrupted forms of the protein to be essentially the same. The ultimate goal of the project is to structurally characterize all the binding partners of eIF3, determine which subunits interact directly, and investigate how subunits may change conformation when they form complexes with other proteins. Research presented herein is the first report showing retention of solution conformation of a protein as evidenced by CCS measurements of both recombinant and solvent disrupted versions of the same protein.     

Safe and Distributed Kinodynamic Replanning for Vehicular Networks

This work deals with the problem of planning collision-free motions for multiple communicating vehicles that operate in the same, partially-observable environment in real-time. A challenging aspect of this problem is how to utilize communication so that vehicles do not reach states from which collisions cannot be avoided due to second-order motion constraints. This paper initially shows how it is possible to provide theoretical safety guarantees with a priority-based coordination scheme. Safety means avoiding collisions with obstacles and between vehicles. This notion is also extended to include the retainment of a communication network when the vehicles operate as a networked team. The paper then progresses to extend this safety framework into a fully distributed communication protocol for real-time planning. The proposed algorithm integrates sampling-based motion planners with message-passing protocols for distributed constraint optimization. Each vehicle uses the motion planner to generate candidate feasible trajectories and the message-passing protocol for selecting a safe and compatible trajectory. The existence of such trajectories is guaranteed by the overall approach. The theoretical results have also been experimentally confirmed with a distributed simulator built on a cluster of processors and using applications such as coordinated exploration. Furthermore, experiments show that the distributed protocol has better scalability properties when compared against the priority-based scheme. Part of the material presented in this paper has appeared in two conference publications: “A Decentralized Planner that Guarantees the Safety of Communicating Vehicles with Complex Dynamics that Replan Online” at IROS 2007 and “A Distributed Protocol for Safe Real-Time Planning of Communicating Vehicles with Second-Order Dynamics” at ROBOCOMM 2007.     

A multi-parametric programming approach for constrained dynamic programming problems

In this work, we present a new algorithm for solving complex multi-stage optimization problems involving hard constraints and uncertainties, based on dynamic and multi-parametric programming techniques. Each echelon of the dynamic programming procedure, typically employed in the context of multi-stage optimization models, is interpreted as a multi-parametric optimization problem, with the present states and future decision variables being the parameters, while the present decisions the corresponding optimization variables. This reformulation significantly reduces the dimension of the original problem, essentially to a set of lower dimensional multi-parametric programs, which are sequentially solved. Furthermore, the use of sensitivity analysis circumvents non-convexities that naturally arise in constrained dynamic programming problems. The potential application of the proposed novel framework to robust constrained optimal control is highlighted.     

Multi-product economic lot scheduling problem with separate production lines for manufacturing and remanufacturing

We study the economic lot scheduling problem with two production sources, manufacturing and remanufacturing, for which operations are performed on separate, dedicated lines. We develop an exact algorithm for finding the optimal common-cycle-time policy. The algorithm combines a search for the optimal cycle time with a mixed integer programming (MIP) formulation of the problem given a fixed cycle time. Using case study data from an auto part producer, we perform a sensitivity study on the effects of key problem parameters such as demand rates and return fractions. Furthermore, by comparing to results in Tang and Teunter [Tang, O., Teunter, R.H., 2006. Economic lot scheduling problem with returns. Production and Operations Management] for the situation where all operations are performed on the same line, we analyze the cost benefits of using dedicated lines.     

A novel mechanism for provisioning of high-level quality of service information in grid environments

Grids, like other heterogeneous systems, have reached the level of maturity where they are addressing the Quality of Service (QoS) provision aspect as a fundamental part of their architecture. However, due to the multi-layer nature of these environments, the QoS characteristics of the infrastructure are revealed to the service-consumer through a complex procedure, in which each layer maps its own QoS parameters to another. Most of these approaches are starting the delegation of QoS information from the service provider’s side, resulting in delivering low-level terms to the service consumer. In this paper, we define the architecture of a mechanism that is able to provide application-oriented and user-specific QoS information in the internal layers of the Grid middleware. This way, it enables the service consumer and especially the end-user to express his business perspectives through the service level agreement life cycle. We also demonstrate the operation of this mechanism and evaluate its performance using a specific Grid scenario.