The Effects of Information and Interactions on Contagion Processes

The network literature commonly neglects the importance of a clear distinction between interactions and information exchanges. Although convenient, this oversight is not innocuous and may lead to erroneous conclusions when looking at mechanisms such as contagion processes. We use simulation methods and conduct a systematic analysis of the implications of such omission. We show that the lack of distinction between information and interaction structures is not without consequences. More precisely, when agents use a myopic best response, only information exchanges matter and interactions can be ignored. With imitation however, both information and interactions play important yet different roles in contagion.contagion, networks, coordination games, scale-free, small-worlds, best response, imitation

What Matters Most: Information or Interaction? The Importance of Behavioral Rules on Network Effects for Contagion Processes

We consider a finite population of agents and define a contagion process as the dynamics by which an action, which is initially played by only a small subset of agents, is adopted by the entire population. Each agent has a set of neighbors with whom he shares information and a set of partners with whom he plays a game. These two sets may or may not coincide. Each period, agents choose their actions based on what they observe from their neighbors, and get some payoff from playing a game with their partners. We show that contagion of an action that is risk dominant and efficient is obtained through partners when agents imitate-the-best, and through neighbors when agents use a myopic best response.

Provider diversity in the NHS: impact on quality and innovation

The overall objective of the research project has been to assess the impact of provider diversity on quality and innovation in the NHS. The specific research aims were to identify the differences in performance between non-profit Third Sector organisations, for-profit private enterprises, and incumbent public sector institutions within the NHS as providers of health care services, as well as the factors that affect the entry and growth of new private and Third Sector providers. The study used both qualitative and quantitative methods based on case studies of four Local Health Economies (LHEs). Qualitative methods included documentary analysis and interviews with key informants and managers of both commissioning and provider organisations. To provide a focus to the study, two tracer conditions were followed: orthopaedic surgery and home health care for frail older people. In the case of hospital inpatient care, data on patient characteristics were also collected from the HES database. The analysis of this data provided preliminary estimates of the effects of provider type on quality, controlling for client characteristics and case mix. In addition, a survey of patient experience in diverse provider organisations was analysed to compare the different dimensions of quality of provision of acute services between incumbent NHS organisations and new independent sector treatment centres. The research has shown that, in respect of inpatient hospital services, diverse providers supply health services of at least as good quality as traditional NHS providers, and that there is ample opportunity to expand their scale and scope as providers of services commissioned by the NHS. The research used patient experience survey data to investigate whether hospital ownership affects the quality of services reported by NHS patients in areas other than clinical quality. The raw survey data appear to show that private hospitals provide higher quality services than the public hospitals. However, further empirical analysis leads to a more nuanced understanding of the performance differences. Firstly, the analysis shows that each sector offers greater quality in certain specialties. Secondly, the analysis shows that differences in the quality of patients’ reported experience are mainly attributable to patient characteristics, the selection of patients into each type of hospital, and the characteristics of individual hospitals, rather than to hospital ownership as such. Controlling for such differences, NHS patients are on average likely to experience a similar quality of care in a public or privately-run hospital. Nevertheless, for specific groups of patients and for specific types of treatments, especially the more straightforward ones, the private sector provides an improved patient experience compared to the public sector. Elsewhere, the NHS continues to provide a high quality service and outperforms the private sector in a range of services and for a range of clients

EM Monitoring and classification of IEMI and protocol-based attacks on IEEE 802.11n communication networks

International audienceThe development of connected devices and their daily use are today at the origin of the omnipresence of Wi-Fi wireless networks. However, these Wi-Fi networks are often vulnerable, and can be used by malicious people to disturb services, intercept sensitive data or to gain access to system. In railways, trains are now equipped with wireless communication systems for operational purposes or for passenger services. In both cases, defense strategies have to be developed to prevent misuses of the networks. The first objective of this study is to propose a monitoring solution, which is independent of the communication networks, to detect the occurrence of attacks. The second objective is to develop a method able to classify attacks of different types: the intentional electromagnetic interference (IEMI), i.e., jamming attacks, and the protocol-based attacks. This study focuses on the IEEE 802.11n Wi-Fi protocol. To perform these analyses, we propose to monitor and to analyze electromagnetic (EM) signals received by a monitoring antenna and a receiver collecting EM spectra. After that, we build a classification protocol following two steps: the first consists in the construction of a Support Vector Machine (SVM) classification model using the collected spectra and the second step uses this SVM model to predict the class of the attack (if any). A time-based correction of this prediction using the nearest neighbors is also included in this second step

The CAMKK2-AMPK kinase pathway mediates the synaptotoxic effects of Aβ oligomers through Tau phosphorylation

Amyloid-β 1-42 (Aβ42) oligomers are synaptotoxic for excitatory cortical and hippocampal neurons and might play a role in early stages of Alzheimer's disease (AD) progression. Recent results suggested that Aβ42 oligomers trigger activation of AMP-activated kinase (AMPK), and its activation is increased in the brain of patients with AD. We show that increased intracellular calcium [Ca²⁺](i) induced by NMDA receptor activation or membrane depolarization activates AMPK in a CAMKK2-dependent manner. CAMKK2 or AMPK overactivation is sufficient to induce dendritic spine loss. Conversely, inhibiting their activity protects hippocampal neurons against synaptotoxic effects of Aβ42 oligomers in vitro and against the loss of dendritic spines observed in the human APP(SWE,IND)-expressing transgenic mouse model in vivo. AMPK phosphorylates Tau on KxGS motif S262, and expression of Tau S262A inhibits the synaptotoxic effects of Aβ42 oligomers. Our results identify a CAMKK2-AMPK-Tau pathway as a critical mediator of the synaptotoxic effects of Aβ42 oligomers

The high resolution structure of tyrocidine A reveals an amphipathic dimer

AbstractTyrocidine A, one of the first antibiotics ever to be discovered, is a cyclic decapeptide that binds to membranes of target bacteria, disrupting their integrity. It is active against a broad spectrum of Gram-positive organisms, and has recently engendered interest as a potential scaffold for the development of new drugs to combat antibiotic-resistant pathogens. We present here the X-ray crystal structure of tyrocidine A at a resolution of 0.95Å. The structure reveals that tyrocidine forms an intimate and highly amphipathic homodimer made up of four beta strands that associate into a single, highly curved antiparallel beta sheet. We used surface plasmon resonance and potassium efflux assays to demonstrate that tyrocidine binds tightly to mimetics of bacterial membranes with an apparent dissociation constant (KD) of 10μM, and efficiently permeabilizes bacterial cells at concentrations equal to and below the KD. Using variant forms of tyrocidine in which the fluorescent probe p-cyano-phenylalanine had been inserted on either the polar or apolar face of the molecule, we performed fluorescence quenching experiments, using both water-soluble and membrane-embedded quenchers. The quenching results, together with the structure, strongly support a membrane association model in which the convex, apolar face of tyrocidine's beta sheet is oriented toward the membrane interior, while the concave, polar face is presented to the aqueous phase

Cyber Security of the Railway wireless system: detection, decision and Human-in-the-Loop

TRA 2018, 7th Transport Research Arena, Vienne, AUTRICHE, 16-/04/2018 - 19/04/2018The networks used in the Railway domain are usually heterogeneous, not enough protected and not fitted to the usual Cyber Security requirements in terms of sustainability, protection and attack detection. Furthermore, the quick evolution of the telecommunication means, the threats and the sustainability aspects have to be taken into account in order to protect the Railway system. The paper presents the first contributions on Cyber Security for railways that can be divided into three main aspects dealing with the Cyber Security of the wireless part of the railway communication system: detection, decision and Human-in-the-Loop. Part of the work will be devoted to the development of an Open Pluggable Framework (OPF). The OPF is a software framework based on automation principles. It monitors the environment, then some algorithms detect abnormal behaviours, and next, OPF decides which reaction to take and finally apply this action (e.g. an alarm or a reconfiguration). The last part 'human in the loop' aims at answering the questions: what happens if the automatic countermeasures fail and how the driver can cope with the attack consequences. It consists in placing professional drivers and Central Traffic Control operators in a realistic simulator and playing scenarios involving attacks and observing the reactions of the professional drivers. A preliminary methodology is proposed and discussed through a concrete case study

Peptide Immunization Indicates that CD8+ T Cells are the Dominant Effector Cells in Trinitrophenyl-Specific Contact Hypersensitivity

The identity of the effector T cell population involved in contact hypersensitivity is still questionable with evidence promoting both CD4+ or CD8+ T cells. Previous experimental studies have relied on the in vivo depletion of T cell subsets using antibody, or the use of knock-out mice with deficiencies in either CD4+ or CD8+ T cell-mediated immunity. To address the role of the class I- and class II-mediated pathways of T cell activation in contact hypersensitivity responses in mice with an intact immune system, we utilized various trinitrophenyl-derivatized peptides, which bind specifically with H-2Kb (major histocompatibility complex class I) or H-2I-Ab (major histocompatibility complex class II). The subcutaneous injection of major histocompatibility complex class II-specific, but not of class I-binding, hapten-derivatized peptides in incomplete Freund's adjuvant induced specific, albeit low, contact hypersensitivity responsiveness to trinitrochlorobenzene. When bone-marrow-derived dendritic cells, however, were pulsed with the same peptides and administered intradermally, the opposite result was observed, namely that the class I binding peptides induced contact hypersensitivity responses similar to that observed after epicutaneous trinitrochlorobenzene application. In contrast, dendritic cells pulsed with major histocompatibility complex class II binding peptides did not reproducibly sensitize for contact hypersensitivity responses. Surprisingly, both immunization protocols efficiently induced CD8+ effector T cells. These results support the notion that CD8+ T cells are the dominant effector population mediating contact hypersensitivity responsiveness and that the CD4+ T cell subset only contributes little if at all

Evaluation of PM2.5 Surface Concentration Simulated by Version 1 of the Nasa's MERRA Aerosol Reanalysis Over Israel and Taiwan

Version 1 of the NASA MERRA Aerosol Reanalysis (MERRAero) assimilates bias-corrected 18 aerosol optical depth (AOD) data from MODIS-Terra and MODIS-Aqua, and simulates particulate 19 matter (PM) concentration data to reproduce a consistent database of AOD and PM concentration around 20 the world from 2002 to the end of 2015. The purpose of this paper is to evaluate MERRAeros simulation 21 of fine PM concentration against surface measurements in two regions of the world with relatively high 22 levels of PM concentration but with profoundly different PM composition, those of Israel and Taiwan. 23 Being surrounded by major deserts, Israels PM load is characterized by a significant contribution of 24 mineral dust, and secondary contributions of sea salt particles, given its proximity to the Mediterranean 25 Sea, and sulfate particles originating from Israels own urban activities and transported from Europe. 26 Taiwans PM load is composed primarily of anthropogenic particles (sulfate, nitrate and carbonaceous 27 particles) locally produced or transported from China, with an additional contribution of springtime 28 transport of mineral dust originating from Chinese and Mongolian deserts. The evaluation in Israel 29 produced favorable results with MERRAero slightly overestimating measurements by 6 on average 30 and reproducing an excellent year-to-year and seasonal fluctuation. The evaluation in Taiwan was less 31 favorable with MERRAero underestimating measurements by 42 on average. Two likely reasons 32 explain this discrepancy: emissions of anthropogenic PM and their precursors are largely uncertain in 33 China, and MERRAero doesnt include nitrate particles in its simulation, a pollutant of predominately 34 anthropogenic sources. MERRAero nevertheless simulates well the concentration of fine PM during the 35 summer, when Taiwan is least affected by the advection of pollution from China