The magmatic system beneath the Tristan da Cunha Island: Insights from thermobarometry, melting models and geophysics

This study provides new insights on the conditions of melt generation and of magma transport and storage beneath Tristan da Cunha Island in the South Atlantic. Situated at the seaward end of the Walvis Ridge-guyot hotspot track, this island is related to the evolving magmatic system of the Tristan plume. Much is known about the geochemical and isotopic composition of the alkaline lavas on Tristan, but the pressure-temperature conditions of the hotspot magmas are under-explored. This contribution reports new data from a suite of 10 samples collected during a geologic-geophysical expedition in 2012. The focus of this study is on the least-evolved, phenocryst-rich basanite lavas but we also included a sample of trachyandesite lava erupted in 1961. Mineral-melt equilibrium thermobarometry uses the composition of olivine, clinopyroxene and plagioclase phenocrysts. In addition to bulk-rock data we also analysed olivine-hosted melt inclusions for the P-T calculations. The results for olivine-melt and clinopyroxene-melt calculations suggest crystallization conditions of around 1200-1250. °C and 0.8-1.3. GPa for the least-evolved magmas (ankaramitic basanites). Combined with seismological evidence for a Moho depth of about 19. km, these results imply magma storage and partial crystallization of Tristan magmas in the uppermost mantle and at Moho level. The trachyandesite yielded values of about 1000. °C and 0.2-0.3. GPa (6 to 10. km depth), indicating further crystallization within the crust.Constraints on the depth and degree of melting at the source of Tristan basanites were derived from REE inverse modelling using our new trace element data. The model predicts 5% melt generation from a melting column with its base at 80-100. km and a top at 60. km, which is consistent with the lithospheric thickness resulting from cooling models and seismological observations. The thermobarometry and melting models combined suggest a mantle potential temperature of about 1360. °C for the Tristan hotspot

Programmable Edge-to-Cloud Virtualization for 5G Media Industry: The 5G-MEDIA Approach

To ensure high Quality of Experience (QoE) for end users, many media applications require significant quantities of computing and network resources, making their realization challenging in resource constrained environments. In this paper, we present the approach of the 5G-MEDIA project, providing an integrated programmable service platform for the development, design and operations of media applications in 5G networks, facilitating media service management across the service life cycle. The platform offers tools to service developers for efficient development, testing and continuous correction of services. One step further, it provides a service virtualization platform offering horizontal services, such as a Media Service Catalogue and accounting services, as well as optimization mechanisms to flexibly adapt service operations to dynamic conditions with efficient use of infrastructure resources. The paper outlines three use cases where the platform was tested and validated

Towards Serverless NFV for 5G Media Applications

The advent of virtualization and IaaS have revolutionized the telecom industry via SDN/NFV. A new wave of cloud-native PaaS promises to further improve SDN/NFV performance, portability, and cost-efficiency. In this poster, we highlight a work in progress being done in the 5G-MEDIA project [2], which pioneers the application of the serverless paradigm to NFV in the context of media intensive applications in 5G networks. Motivational use cases include tele-immersive gaming, mobile journalism and UHD content distribution. For example, consider a next-gen e-sport, in which bouts between gamers last only a few minutes. FaaS offers a clear cost-efficiency benefit for hosting such applications. An architecture is shown in Fig. 1. It includes i) an Application/Service Development Kit (SDK) to enable access to media applications development tools; ii) a Service Virtualization Platform (SVP) to run the ETSI MANO framework, the Media Service MAPE optimization component and the VIM and WIM plugins to enable NFVIs integration; iii) different NFVIs to execute media-specific VNFs. FaaS VIM is implemented for integration of FaaS with the rest of the MANO stack. It allows mixing FaaS and "regular" VNFs within the same media forwarding graph. For reference implementation, Apache OpenWhisk [1] and Kubernetes are used. The main challenge is extending the programming model to support groups of actions communicating over a network, while retaining the simplicity of FaaS

A service platform architecture enabling programmable edge-to-cloud virtualization for the 5G Media industry

Media applications are amongst the most demanding services in terms of resources, requiring huge network capacity for high bandwidth audio-visual and other mobile sensory streams. The 5G-MEDIA project aims at innovating media-related applications by investigating how these applications and the underlying 5G network should be coupled and interwork to the benefit of both. The 5G-MEDIA approach aims at delivering an integrated programmable service platform for the development, design and operations of media applications in 5G networks by providing mechanisms to flexibly adapt service operations to dynamic conditions and react upon events (e.g. to transparently accommodate auto-scaling of resources, VNF replacement, etc.). In this paper we present the 5G-MEDIA service platform architecture, which has been specifically designed to enable the development and operation of services for the nascent 5G media industry. Our approach delivers an integrated programmable service platform for the development, design and operations of media applications in 5G networks

Actionable perturbations of damage responses by TCL1/ATM and epigenetic lesions form the basis of T-PLL

T-cell prolymphocytic leukemia (T-PLL) is a rare and poor-prognostic mature T-cell malignancy. Here we integrated large-scale profiling data of alterations in gene expression, allelic copy number (CN), and nucleotide sequences in 111 well-characterized patients. Besides prominent signatures of T-cell activation and prevalent clonal variants, we also identify novel hot-spots for CN variability, fusion molecules, alternative transcripts, and progression-associated dynamics. The overall lesional spectrum of T-PLL is mainly annotated to axes of DNA damage responses, T-cell receptor/cytokine signaling, and histone modulation. We formulate a multi-dimensional model of T-PLL pathogenesis centered around a unique combination of TCL1 overexpression with damaging ATM aberrations as initiating core lesions. The effects imposed by TCL1 cooperate with compromised ATM toward a leukemogenic phenotype of impaired DNA damage processing. Dysfunctional ATM appears inefficient in alleviating elevated redox burdens and telomere attrition and in evoking a p53-dependent apoptotic response to genotoxic insults. As non-genotoxic strategies, synergistic combinations of p53 reactivators and deacetylase inhibitors reinstate such cell death execution.Peer reviewe

Improving Performance of a Distributed File System Using OSDs and Cooperative Cache

zFS is a scalable distributed file system that uses Object Store Devices (OSDs) for storage management and a set of cooperative machines for distributed file management. zFS evolved from the DSF project [7], and its high-level architecture is described in [11]. This work uses a cooperative cache algorithm, which is resilient to network delays and nodes failure. The work explores the effectiveness of this algorithm and of zFS as a file system. This is accomplished by comparing the system’s performance to NFS using the IOZONE[8] benchmark. We also investigate whether using a cooperative cache results in better performance, despite the fact that OSDs have their own caches. Our results show that the zFS prototype performs better than NFS when cooperative cache is activated and that zFS provides better performance even though the OSDs have caches of their own. We also demonstrate that using pre-fetching in zFS increases performance significantly. Thus, zFS performance scales well when the number of participating clients increases.

What is the maximum solid phase concentration in volcanic turbulent gas-particle mixtures? Experimental observations and implications for natural flows

International audienc

Experimental Measurement of the Solid Particle Concentration in Geophysical Turbulent Gas-Particle Mixtures

Co-auteur étrangerInternational audienceDilute gas-particle mixtures in which the particles are carried by the turbulent fluid are found invarious geophysical contexts, from cold snow avalanches to hot pyroclastic density currents. Thoughprevious studies suggest that such mixtures have maximum particle concentrations of a few volume percent,the dependence of this maximum concentration on the Reynolds number is unclear. We addressed this issuethrough laboratory experiments in a vertical pipe, where dilute gas-particle mixtures were created byinjecting a turbulent air flow from below. Nearly monodisperse mixtures of glass beads of different grain sizes(77 to 1,550 μm) were used with varying bulk concentrations from 0.025 to 8 vol. %. To create quasi-staticmixtures, the mean air velocity matched the terminal settling velocity for the grain sizes investigated. Themaximum Reynolds numbers of the mixtures were ~104–106. The air pressure indicated full support of theparticle weight at concentrations down to 0.025 vol. %. Above a critical particle concentration, at which allthe particles were suspended, subsequent additional particles were not maintained in the mixture and led tothe formation of clusters that settled downward in the pipe to form a dense fluidized bed. Maximummean particle concentrations of the dilute mixtures increased from ~1 to ~2.8 vol. % and reached a plateau atincreasing mixture Reynolds number. These results give insights into the maximum particle concentrations ofgeophysical turbulent gas-particle mixtures and may serve to constrain observations as well as the inputand output data of models