Evaluation of the Random Token Protocol for High-Speed and Radio Networks

In high-speed communication networks, the ratio between the end-to-end propagation delay to packet transmission time is large, causing increased scheduling overhead in demand assignment protocols and increased collision probabilities in random access schemes. These lead to rapid degradation of the channel utilization in both channel access control approaches. In this paper, we present a "random token" oriented protocol where channel access is scheduled by random, implicit token passing leading to lower channel access control penalty. By optimally balancing the collision and scheduling penalties, the protocol allows the network to reach better performance than that obtained from random access schemes in networks with and without collision detection, without imposing additional system operational assumptions. Specifically, the random token protocol does not require knowledge of the number of stations, their identities, or synchronization in periods of silence. Therefore, the protocol is also suitable for high-speed networks with frequent reconfiguration and for mobile radio networks.     

Prioritized demand assignment protocols and their evaluation

A class of message-based or station-based priority protocols for demand-assignment-based local area networks (LANs), such as Token Bus, HYPERbus, LCN, etc., is defined. It is shown how existing priority protocols can be represented within this class and how they can be extended for a more efficient realization with regard to both delay and capacity of prioritized channel access in LANs. An analytic approach for analyzing multiple-access systems operating under prioritized demand assignment protocols is introduced. The approach permits the modeling of station-dependent and priority-dependent arrival rates and generally distributed transmission times. The introduced finite-population model is especially appropriate for prioritized systems where the number of users per priority class is typically small and users place different service demands on the system. For modeling systems with large populations of users, an approximate model, which is shown to be significantly more computationally efficient than the exact model without imposing additional modeling restrictions, is introduced     

Whiteness and tint formulas of the Commission Internationale de l'Eclairage: approximations in the Lab color space

Linear approximations to the whiteness and tint formulas of the Commission Internationale de l'Eclairage (CIE) are presented in the CIE L*a*b* color system.     

Performance of Multibeam Packet Satellite Systems with Conflict Free Scheduling

The concept of a multibeam satellite system With on-board processing and memory is studied. In this system multiple slotted ALOHA uplinks carry the traffic to the satellite. Packets are accepted at the satellite, when memory is available, and are routed to their destination zones using a TDM protocol. We present a model which can be used to evaluate a satellite system with conflict-free scheduling, i.e., a system in which several packets can be simultaneously chosen for downlink transmissions, given each earth zone is served by at most one satellite transponder in each slot. We compute the system throughput, packet delays, and buffer overflow probabilities for a general configuration. It is shown that for some configurations the one beam per zone restriction can have a significant effect on the system performance. The presented model can be also used to evaluate satellite systems when this restriction is removed and to evaluate a variety of other satellite systems.     

Die einzelnen Lebensmittel (Chemie, Technologie, Analytik)

Ohne Zusammenfassung     

Sex differences in vascular dysfunction and cardiovascular outcomes: The cardiac,endothelial function,and arterial stiffness in ESRD (CERES) study

Introduction: Recent studies suggest that women with end‐stage renal disease (ESRD) may have higher rates of mortality than men, but it is unknown whether sex differences in vascular function explain this disparity. The cardiac, endothelial function, and arterial stiffness in ESRD (CERES) study is an ongoing, prospective observational study designed to investigate vascular function, myocardial injury, and cardiovascular outcomes in ESRD. Methods: Among 200 CERES participants (34% women), we evaluated arterial wave reflections as augmentation index normalized to a heart rate of 75 (AIx75), arterial stiffness as pulse wave velocity, and macro‐ and microvascular endothelial dysfunction as flow‐mediated dilation and velocity time integral (VTI). Over a median of 14 months, participants were followed for the composite outcome of cardiovascular hospitalization or all‐cause death. Findings : Women had higher arterial wave reflection (Mean, SD AIx75 30% ± 9% for women vs. 21% ± 10% for men; P < 0.001) and worse microvascular function (VTI 55 ± 30 cm for women vs. 70 ± 27 cm for men; P = 0.007). After multivariable adjustment, female sex remained associated with a 0.5‐SD higher AIx75 (95% CI [0.01, 0.9]) and 0.3‐SD lower VTI (95%CI [0.1, 0.7]). Women experienced higher adjusted rates of the composite outcome (HR 2.5; 95%CI [1.1, 5.6]; P = 0.03), and further adjustment for arterial wave reflection attenuated this risk. Discussion: Vascular dysfunction may partly explain the association of female sex with higher cardiovascular risk and mortality in patients with ESRD. Further studies are needed to explore whether sex differences in vascular function predict long‐term outcomes, and whether hormonal or inflammatory factors explain these associations.     

Quantum leader election

A group of n individuals \(A_{1},\ldots A_{n}\) who do not trust each other and are located far away from each other, want to select a leader. This is the leader election problem, a natural extension of the coin flipping problem to n players. We want a protocol which will guarantee that an honest player will have at least \(\frac{1}{n}-\epsilon \) chance of winning (\(\forall \epsilon >0\)), regardless of what the other players do (whether they are honest, cheating alone or in groups). It is known to be impossible classically. This work gives a simple algorithm that does it, based on the weak coin flipping protocol with arbitrarily small bias derived by Mochon (Quantum weak coin flipping with arbitrarily small bias, arXiv:0711.4114, 2000) in 2007, and recently published and simplified in Aharonov et al. (SIAM J Comput, 2016). A protocol with linear number of coin flipping rounds is quite simple to achieve; we further provide an improvement to logarithmic number of coin flipping rounds. This is a much improved journal version of a preprint posted in 2009; the first protocol with linear number of rounds was achieved independently also by Aharon and Silman (New J Phys 12:033027, 2010) around the same time.     

A Bayesian framework for automated cardiovascular risk scoring on standard lumbar radiographs

We present a fully automated framework for scoring a patient's risk of cardiovascular disease (CVD) and mortality from a standard lateral radiograph of the lumbar aorta. The framework segments abdominal aortic calcifications for computing a CVD risk score and performs a survival analysis to validate the score. Since the aorta is invisible on X-ray images, its position is reasoned from 1) the shape and location of the lumbar vertebrae and 2) the location, shape, and orientation of potential calcifications. The proposed framework follows the principle of Bayesian inference, which has several advantages in the complex task of segmenting aortic calcifications. Bayesian modeling allows us to compute CVD risk scores conditioned on the seen calcifications by formulating distributions, dependencies, and constraints on the unknown parameters. We evaluate the framework on two datasets consisting of 351 and 462 standard lumbar radiographs, respectively. Promising results indicate that the framework has potential applications in diagnosis, treatment planning, and the study of drug effects related to CVD.     

A Centralized MAC Protocol for QoS Support in UWB-Based Wireless Networks

In this paper we introduce a novel MAC protocol that provides Quality of Service (QoS) support for multimedia traffic in UWB-based wireless local area networks. The proposed protocol allocates transmission opportunities to QoS and best effort traffic using a set of scheduling and resource control algorithms. The algorithms account for the UWB characteristics such as the co-existence of multiple simultaneous transmissions as well as the possibility of dynamically assigning the nodes' transmission rate and power. The simulation results show that the proposed protocol can provide QoS support while optimizing resource utilization. Yuechun Chu received her B.Sc. degree in electrical engineering from Shanghai University, China, in 1996 and M.Sc. degree in electrical engineering from University of Science and Technology of China in 1999. She is currently pursuing the Ph.D. degree in the department of electrical and computer engineering at the University of Massachusetts Amherst. Her research interests include MAC protocol design for UWB-based networks, wireless multimedia applications, and architectures and protocols for wireless networks with QoS guarantees. Aura Ganz is currently an Associate Professor and Director of the Multimedia Networks Laboratory at the ECE Department, University of Massachusetts at Amherst. She has experience in topics related to multimedia wireless networks, optical networks and ubiquitous computing. The research results are validated by a combination of analytical, simulation and prototyping tools. She has published a book “Multimedia Wireless Networks: Technologies, Standards and QoS” (Prentice Hall) and authored over one hundred and fifty peer reviewed publications. Dr. Ganz received her BSc, MSc and Ph.D degrees in Computer Science from the Technion in Israel.