Enabling decentralized wireless index coding in practice

Index coding is a problem in theoretical computer science and network information theory that studies the optimal coding scheme for transmitting multiple messages across a network to receivers with different side information. The ultimate goal of index coding is to reduce transmission time in a communication network by minimizing the number of messages based on shared information. Index coding theory extends to several key engineering problems in network communication including peer to peer communication, distributed broadcast networks, and interference alignment. Although the theoretical connection between index coding and wireless networks is valuable, we focus on finding index coding strategies for a realistic wireless network. More specifically, we investigate how index coding can be applied to an OFDMA downlink network during the retransmission phase. An orthogonal frequency-division multiple access (OFDMA) downlink network is a network where data is sent downward from a designated higher-level transmitter to a group of receiving nodes. In addition, receivers can often decode the other receivers' physical layer signals on the other sub-channels that can be exploited as side information. If this side information is sent back to the transmitter, it can then be coded to cancel the interference in subsequent retransmission phases resulting in fewer retransmission messages. In this report, we explain the coding model and characterize the benefits of index coding for retransmissions within an OFDMA downlink network. In addition, we demonstrate the results of applying this index coding scheme in such network in both simulation and in an active wireless mesh network.Electrical and Computer Engineerin

Disability Benefits as Social Insurance: Tradeoffs Between Screening Stringency and Benefit Generosity in Optimal Program Design

The Social Security Disability Insurance (SSDI) system is designed to provide income security to workers in the event that health problems prevent them from working. In order to qualify for benefits, applicants must pass a medical screening that is intended to verify that the individual is truly incapable of work. Past research has shown, however, that the screening procedures used do not function without error. If screening were error-free, it has can be demonstrated that it is socially optimal to distinguish the disabled non-worker from the non-disabled, providing benefits to the disabled. In this paper we first demonstrate that if the errors in the medical screening are too large, it will not be optimal to distinguish the disabled from the non-disabled. Then, we use data on the actual quality of screening to determine first, if segmenting the non-working population is desirable, and second whether the current SSDI system relies too heavily on screening than is justified. Our preliminary conclusion is that while screening is good enough to justify some distinction in benefits, it may not be good enough to justify the size of the benefit offered.

Quantum Correlations in Nonlocal BosonSampling

Determination of the quantum nature of correlations between two spatially separated systems plays a crucial role in quantum information science. Of particular interest is the questions of if and how these correlations enable quantum information protocols to be more powerful. Here, we report on a distributed quantum computation protocol in which the input and output quantum states are considered to be classically correlated in quantum informatics. Nevertheless, we show that the correlations between the outcomes of the measurements on the output state cannot be efficiently simulated using classical algorithms. Crucially, at the same time, local measurement outcomes can be efficiently simulated on classical computers. We show that the only known classicality criterion violated by the input and output states in our protocol is the one used in quantum optics, namely, phase-space nonclassicality. As a result, we argue that the global phase-space nonclassicality inherent within the output state of our protocol represents true quantum correlations.Comment: 5 pages, 1 figure, comments are very welcome

Quantum Correlations and Global Coherence in Distributed Quantum Computing

Deviations from classical physics when distant quantum systems become correlated are interesting both fundamentally and operationally. There exist situations where the correlations enable collaborative tasks that are impossible within the classical formalism. Here, we consider the efficiency of quantum computation protocols compared to classical ones as a benchmark for separating quantum and classical resources and argue that the computational advantage of collaborative quantum protocols in the discrete variable domain implies the nonclassicality of correlations. By analysing a toy model, it turns out that this argument implies the existence of quantum correlations distinct from entanglement and discord. We characterize such quantum correlations in terms of the net global coherence resources inherent within quantum states and show that entanglement and discord can be understood as special cases of our general framework. Finally, we provide an operational interpretation of such correlations as those allowing two distant parties to increase their respective local quantum computational resources only using locally incoherent operations and classical communication.Comment: Minor modifications and correction

What can quantum optics say about computational complexity theory?

Considering the problem of sampling from the output photon-counting probability distribution of a linear-optical network for input Gaussian states, we obtain results that are of interest from both quantum theory and the computational complexity theory point of view. We derive a general formula for calculating the output probabilities, and by considering input thermal states, we show that the output probabilities are proportional to permanents of positive-semidefinite Hermitian matrices. It is believed that approximating permanents of complex matrices in general is a #P-hard problem. However, we show that these permanents can be approximated with an algorithm in BPP^NP complexity class, as there exists an efficient classical algorithm for sampling from the output probability distribution. We further consider input squeezed-vacuum states and discuss the complexity of sampling from the probability distribution at the output.Comment: 5 pages, 1 figur

MATDB ONLINE—A STANDARDS-BASED SYSTEM FOR PRESERVING, MANAGING, AND EXCHANGING ENGINEERING MATERIALS TEST DATA

With ICT Standards playing a key role in support of research and development in many disciplines, the European Commission Institute for Energy and Transport is keen to promote the development and adoption of ICT Standards for engineering data. In this respect, its MatDB Online facility is a Standards-based system for preserving, managing, and exchanging engineering materials test data. While MatDB Online has evolved over more than 30 years to incorporate the latest innovations in data preservation and exchange, such as XML-based data transfer and data citation using digital object identifiers, it continues to rely on a robust data model developed more than 30 years ago through the joint efforts of the National Research Institute for Metals (the predecessor to NIMS, the National Institute for Materials Science), the European Commission Joint Research Centre, and the National Institute of Standards and Technology. While this data model has endured over many years, there is no corresponding Standard. Similarly, related efforts by the engineering materials community to deliver a Standard representation for engineering materials, such as MatML, have failed to be ratified. In consequence of the continued absence of a Standard representation for engineering materials data, there is no common mechanism for preserving and exchanging materials data and no formal means of maintaining a data model to support advances in materials technology, such as the emergence of nanomaterials. It is for these reasons that the European Commission Institute for Energy and Transport is supporting SERES, a CEN Workshop on Standards for Electronic Reporting in the Engineering Sector. As one of more than thirty organisations supporting the SERES Workshop, the Institute for Energy and Transport will make the MatDB XML schema available as one of several resources that will be taken into consideration when the prenormative Standard for representing engineering materials data is formulated. With the participation of the Institute for Energy and Transport in the SERES Workshop taking place in parallel with a related project with Oak Ridge National Laboratory, there is good reason to expect that a Standard representation for engineering materials, which has so far eluded the materials community, will be realised. This paper describes MatDB support for engineering materials Standards and related innovative features.JRC.F.4-Nuclear Reactor Integrity Assessment and Knowledge Managemen

Anti-DLL4, a cancer therapeutic with multiple mechanisms of action

DLL4 is a ligand for the Notch family of receptors. DLL4 has many important functions in normal development and tissue homeostasis, including roles in the immune system, the gastro-intestinal tract, and in vascular development. Because of the importance of Notch signaling in stem cell biology, DLL4 has been investigated for its role in the maintenance and proliferation of cancer stem cells (CSC). In addition, its important role in angiogenesis has been investigated for utility as an anti-angiogenic agent. Preclinical studies have highlighted that both anti-CSC and anti-angiogenic activities contribute to its anti-tumor efficacy, and have supported the clinical development of anti-DLL4 antibody for the treatment of cancer