A note on shell models for MHD Turbulence

We investigate the time evolution of two different (GOY-like) shell models which have been recently proposed to describe the gross features of MHD turbulence. We see that, even if they are formally of the same type sharing with MHD equations quadratic couplings and similar conserved quantities, fundamental differences exist which are related to the ideal invariants.Comment: 6 pages, 5 figures.eps, to appear in Europhysics Letter

Multiple-scattering effects on incoherent neutron scattering in glasses and viscous liquids

Incoherent neutron scattering experiments are simulated for simple dynamic models: a glass (with a smooth distribution of harmonic vibrations) and a viscous liquid (described by schematic mode-coupling equations). In most situations multiple scattering has little influence upon spectral distributions, but it completely distorts the wavenumber-dependent amplitudes. This explains an anomaly observed in recent experiments

Resilient Placement of VNFs and Distributed MANO Components in a WMN-based NFV Infrastructure

Wireless Multi-Radio Outdoor-Routers are building a Wireless Mesh Network (WMN), which is used as an emergency communication infrastructure in case a disaster destroyed the existing communication system. A dynamic service provisioning shall be achieved by integrating Network Function Virtualisation (NFV) into the network. A distributed management and orchestration (MANO), which operates in-band of the network, controls the NFV infrastructure (NFVI). The primary goal of the distributed MANO consists of improving the network resilience to changes affecting the NFVI, namely node and link failures. For this aspect, the position of the Virtual Network Functions (VNFs), implementing a functional service component, as well as the position of the components building the distributed MANO within the WMN-based NFVI is essential. For this purpose, this publication proposes a concept for the resilient placement of the VNFs and distributed MANO components required within the WMN-based NFVI. Furthermore, a mathematical model of the network and an Integer Linear Programming (ILP) based optimisation target for implementing the concept are proposed. The optimisation target considers the connectivity of NFVI-Nodes at the placement by preferring well-connected NFVI-Nodes and avoiding poorly-connected ones. If required due to limited hardware resources, priorities among the different kinds of network functions are considered. Multiple existing solvers are used on the optimisation target to evaluate their performance in terms of their required time for providing an optimal solution based on different network sizes

Reducing health inequality in black, asian and other minority ethnic pregnant women: Impact of first trimester combined screening for placental dysfunction on perinatal mortality.

OBJECTIVE: To assess the impact of the Fetal Medicine Foundation (FMF) first trimester screening algorithm for pre-eclampsia on health disparities for perinatal death amongst minority ethnic groups. DESIGN: A retrospective cohort study from July 2016 to December 2020. SETTING: A large London teaching hospital. PATIENTS AND METHODS: All women who underwent first trimester pre-eclampsia risk assessment using either the NICE screening checklist or the FMF multimodal approach. Women considered at high-risk in the FMF cohort were offered 150mg aspirin before 16 weeks' gestation, serial growth scans and elective birth at 40 weeks. MAIN OUTCOME MEASURES: Stillbirth, neonatal death and perinatal death rates stratified by screening method and maternal ethnicity. RESULTS: In the NICE cohort, the perinatal death rate was significantly higher in non-White versus White women (7.95/1000 vs 2.63/1000 births, OR 3.035, 95% CI 1.551 to 5.941). Following the introduction of FMF screening, the perinatal death rate in non-White women fell from 7.95 to 3.22/1000 births (OR 0.403, 95% CI 0.206 to 0.789), such that it was no longer significantly different from the perinatal mortality rate in White women (3.22/1000 vs 2.55/1000 births, OR 1.261, 95% CI 0.641 to 2.483). CONCLUSIONS: First trimester combined screening for placental dysfunction is associated with a significant reduction in perinatal death in minority ethnic women. Health disparity for perinatal death amongst ethnic minority women demands urgent attention from both clinicians and health policy makers. The data of this study suggests that this ethnic health inequality may be avoidable

Predictors of state-of-the-art management of early breast cancer in Switzerland

Background: The aim of this study was to investigate predictors of state-of-the-art management of early breast cancer in Switzerland. Patients and methods: The study included 3499 women aged 25-79 years diagnosed with invasive breast cancer stages I-IIIA in 2003-2005. Patients were identified through population-based cancer registries and treated in all kinds of settings. Concordance with national and international recommendations was assessed for 10 items covering surgery, radiotherapy, systemic adjuvant therapy and histopathology reporting. We used multivariate logistic regression to identify independent predictors of high (10 points) and low (≤7 points) concordance. Results: In one-third of the patients, management met guidelines in all items, whereas in about one-fifth, three or more items did not comply. Treatment by a surgeon with caseload in the upper tercile and team involved in clinical research were independent predictors of a high score, whereas treatment by a surgeon with a caseload in the lower tercile was associated with a low score. Socioeconomic characteristics such as income and education were not independent predictors, but patient's place of residence and age independently predicted management according to recommendations. Conclusion: Specialization and involvement in clinical research seem to be key elements for enhancing the quality of early breast cancer management at population leve

Possible Challenges and Appropriate Measures for a Resilient WMN-Based Disaster Network

A wireless mesh network (WMN)-based disaster network shall provide an emergency communication infrastructure in case of a catastrophe destroyed any existing communication infrastructure. Since the hardware of the disaster network is deployed in an environment affected by the outcome of a catastrophe, events such as aftershocks and/or outbreaking fires are likely to occur and may destroy the hardware of the disaster network. To maintain its provided functionality and thus its usability, the network requires to be resilient to these and other events which are affecting the network infrastructure. To achieve a resilient network, the normal state of the network as well as possible challenges affecting the normal state need to be defined in prior. This scientific work deals with the derivation and definition of the required normal state of the WMN-based disaster network, as well as the definition of possible challenges resulting from environmental-based events. Since each possible challenge is influencing the network infrastructure of the WMN-based disaster network, possible measures for preventing and/or reducing the impact of each challenge are defined. In addition, emergency corrections capable of resolving the influences of an occurring challenge are defined

High Throughput WMN for the Communication in Disaster Scenario

The Wireless mesh network (WMN) is a popular network architecture used to support disaster recovery operations. However, few research works have addressed the capacity problem of such a network. This is due to the assumption that the communication network in disaster scenario is built to support services with a low rate requirement like delay tolerant messages. At the same time, the demand for higher data rates has increased in recent years due to the digitalisation of rescue operations and the use of new services (e.g. VoIP, drones and robots). Therefore, the capacity of the WMN is becoming a central issue in the design of future WMNs. This paper proposes a Layer 1 cluster-based network to solve the throughput bottleneck in the WMN. The proposed architecture is evaluated by several real world measurements. The obtained results are compared with the theory. The proposed solution shows a throughput improvement compared to a single-radio WMN and a multi-radio WMN using the CoMTaC channel allocation strategy

Energy landscape - a key concept for the dynamics of glasses and liquids

There is a growing belief that the mode coupling theory is the proper microscopic theory for the dynamics of the undercooled liquid above a critical temperature T_c. In addition, there is some evidence that the system leaves the saddlepoints of the energy landscape to settle in the valleys at this critical temperature. Finally, there is a microscopic theory for the entropy at the calorimetric glass transition T_g by Mezard and Parisi, which allows to calculate the Kauzmann temperature from the atomic pair potentials. The dynamics of the frozen glass phase is at present limited to phenomenological models. In the spirit of the energy landscape concept, one considers an ensemble of independent asymmetric double-well potentials with a wide distribution of barrier heights and asymmetries (ADWP or Gilroy-Phillips model). The model gives an excellent description of the relaxation of glasses up to about T_g/4. Above this temperature, the interaction between different relaxation centers begins to play a role. One can show that the interaction reduces the number of relaxation centers needed to bring the shear modulus down to zero by a factor of three.Comment: Contribution to the III Workshop on Nonequilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials, 22-27 September 2002, Pisa; 14 pages, 3 figures; Version 3 takes criticque at Pisa into account; final version 4 will be published in J.Phys.: Condens.Matte