Asymptotically Optimal Approximation Algorithms for Coflow Scheduling

Many modern datacenter applications involve large-scale computations composed of multiple data flows that need to be completed over a shared set of distributed resources. Such a computation completes when all of its flows complete. A useful abstraction for modeling such scenarios is a {\em coflow}, which is a collection of flows (e.g., tasks, packets, data transmissions) that all share the same performance goal. In this paper, we present the first approximation algorithms for scheduling coflows over general network topologies with the objective of minimizing total weighted completion time. We consider two different models for coflows based on the nature of individual flows: circuits, and packets. We design constant-factor polynomial-time approximation algorithms for scheduling packet-based coflows with or without given flow paths, and circuit-based coflows with given flow paths. Furthermore, we give an $O(\log n/\log \log n)$-approximation polynomial time algorithm for scheduling circuit-based coflows where flow paths are not given (here $n$ is the number of network edges). We obtain our results by developing a general framework for coflow schedules, based on interval-indexed linear programs, which may extend to other coflow models and objective functions and may also yield improved approximation bounds for specific network scenarios. We also present an experimental evaluation of our approach for circuit-based coflows that show a performance improvement of at least 22% on average over competing heuristics.Comment: Fixed minor typo

Exoplanet Transit Variability: Bow Shocks and Winds Around HD 189733b

By analogy with the solar system, it is believed that stellar winds will form bow shocks around exoplanets. For hot Jupiters the bow shock will not form directly between the planet and the star, causing an asymmetric distribution of mass around the exoplanet and hence an asymmetric transit. As the planet orbits thorough varying wind conditions, the strength and geometry of its bow shock will change, thus producing transits of varying shape. We model this process using magnetic maps of HD 189733 taken one year apart, coupled with a 3D stellar wind model, to determine the local stellar wind conditions throughout the orbital path of the planet. We predict the time-varying geometry and density of the bow shock that forms around the magnetosphere of the planet and simulate transit light curves. Depending on the nature of the stellar magnetic field, and hence its wind, we find that both the transit duration and ingress time can vary when compared to optical light curves. We conclude that consecutive near-UV transit light curves may vary significantly and can therefore provide an insight into the structure and evolution of the stellar wind.Comment: 9 Pages, 7 figures. Accepted for publication in Monthly Notices of The Royal Astronomical Societ

In silico studies on novel inhibitors of MERS-CoV: Structure-based pharmacophore modeling, database screening and molecular docking

Purpose: To search for novel scaffolds as potential inhibitors of 3CLpro protease enzyme and as antiviral drugs.Methods: NCI database was screened using structure-based  pharmacophore modeling, database screening and molecular docking. Also, Lipininski’s rule of 5 was applied in order to test the druglikenessof the retrieved compound. Pharmacophore modelling and subsequent post-docking analyses were used for comparison of the binding mode of the retrieved hits with that of the x-ray inhibitor, R30, against MERS-CoV 3CLpro enzyme.Results: Five compounds were identified as potential agents for the  treatment of corona virus, MERSCoV, which showed similar binding to MERS-CoV 3CLpro like that of the x-ray inhibitor, R30. As protease enzyme plays an indispensable role during virus life cycle, CoV 3CLpro has been reported as a highly validated drug target and it is considered viable for the design of broad spectrum inhibitors. The selected five hit compounds bind to MERS-CoV 3CLpro in a manner similar to that of the x-ray inhibitor, R30, and showed pharmacophore-fit and docking score values higher than those of R30, MERS-CoV 3CLpro-inhibitor.Conclusion: The retrieved five hits are proposed as new scaffolds for further evaluation and optimization of their activity against MERS-CoV.Keywords: MERS-CoV pharmacophore, Molecular docking, Protease enzyme, X-ray inhibito

Offset effect on the S-Bend structure losses and optimization of its size for integrated optics

The S-Bend structures are heavily exploited to join optical components. Reducing the power loss caused by the curve is the main objective in the design step of these components. However integrated optical circuits require S-Bend waveguide to be low loss and compact sized. In this paper, we present a contribution to link the curved structure to the straight waveguide by using the simulated bend function available in the Beam propagation tool of the Rsoft commercial software package. Simulation results confirm that this approach allows a reduction of the size of the curved structure with offset with relatively minimum of losses for photonic field

Signatures of Star-planet interactions

Planets interact with their host stars through gravity, radiation and magnetic fields, and for those giant planets that orbit their stars within $\sim$10 stellar radii ($\sim$0.1 AU for a sun-like star), star-planet interactions (SPI) are observable with a wide variety of photometric, spectroscopic and spectropolarimetric studies. At such close distances, the planet orbits within the sub-alfv\'enic radius of the star in which the transfer of energy and angular momentum between the two bodies is particularly efficient. The magnetic interactions appear as enhanced stellar activity modulated by the planet as it orbits the star rather than only by stellar rotation. These SPI effects are informative for the study of the internal dynamics and atmospheric evolution of exoplanets. The nature of magnetic SPI is modeled to be strongly affected by both the stellar and planetary magnetic fields, possibly influencing the magnetic activity of both, as well as affecting the irradiation and even the migration of the planet and rotational evolution of the star. As phase-resolved observational techniques are applied to a large statistical sample of hot Jupiter systems, extensions to other tightly orbiting stellar systems, such as smaller planets close to M dwarfs become possible. In these systems, star-planet separations of tens of stellar radii begin to coincide with the radiative habitable zone where planetary magnetic fields are likely a necessary condition for surface habitability.Comment: Accepted for publication in the handbook of exoplanet

Re-architecting datacenter networks and stacks for low latency and high performance

© 2017 ACM. Modern datacenter networks provide very high capacity via redundant Clos topologies and low switch latency, but transport protocols rarely deliver matching performance. We present NDP, a novel datacenter transport architecture that achieves near-optimal completion times for short transfers and high flow throughput in a wide range of scenarios, including incast. NDP switch buffers are very shallow and when they fill the switches trim packets to headers and priority forward the headers. This gives receivers a full view of instantaneous demand from all senders, and is the basis for our novel, high-performance, multipath-aware transport protocol that can deal gracefully with massive incast events and prioritize traffic from different senders on RTT timescales. We implemented NDP in Linux hosts with DPDK, in a software switch, in a NetFPGA-based hardware switch, and in P4. We evaluate NDP's performance in our implementations and in large-scale simulations, simultaneously demonstrating support for very low-latency and high throughput.This work was partly funded by the SSICLOPS H2020 project (644866)

Hepatic Glucose Metabolism of Diabetic Patient Evaluated by 18FDG PET Scan

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Antibacterial effect of Jordanian propolis and isolated flavonoids against human pathogenic bacteria

Propolis is a natural product widely consumed in folk medicine. The present study was carried out to investigate the antibacterial activity of Jordanian propolis, collected from two locations with two different dominant floras (Type1; Pine trees and Type ll; Oak trees). Zones of inhibition and minimum inhibitory concentrations (MICs) were determined on methicillin resistant Staphylococcus aureus (MRSA), multidrug resistant Escherichia coli and standard strains of both bacteria. Propolis Type I and Type II showed antibacterial activity against MRSA (MIC 4.69 and 18.75 μg ml-1, respectively). Crude propolis from Type I showed higher antibacterial activity than Type II against the tested bacteria. Three pure phenolic compounds (three flavonoids) namely, pinobanksin-3-O-acetate, pinocemberin and chrysin, were isolated from fractions I-2 and I-4, and screened in vitro for antibacterial activity. Pinobanksin-3-O-acetate and pinocembrin exhibited antibacterial activity especially against MRSA, while chrysin was only active against standard S. aureus. This is the first report that shows in vitro antibacterial activity of isolated flavonoids from Jordanian propolis against standard and resistant strains of E. coli and MRSA. Overall, results of this study highlight the important role of propolis botanical source on the antibacterial activity of such natural material which might affect its medical applications.Keywords: Antibacterial activity, human pathogens, flavonoids, propolis, methicillin resistant Staphylococcus aureus, Escherichia coliAfrican Journal of Biotechnology Vol. 9(36), pp. 5966-5974, 6 September, 201

On energy consumption of switch-centric data center networks

Data center network (DCN) is the core of cloud computing and accounts for 40% energy spend when compared to cooling system, power distribution and conversion of the whole data center (DC) facility. It is essential to reduce the energy consumption of DCN to esnure energy-efficient (green) data center can be achieved. An analysis of DC performance and efficiency emphasizing the effect of bandwidth provisioning and throughput on energy proportionality of two most common switch-centric DCN topologies: three-tier (3T) and fat tree (FT) based on the amount of actual energy that is turned into computing power are presented. Energy consumption of switch-centric DCNs by realistic simulations is analyzed using GreenCloud simulator. Power related metrics were derived and adapted for the information technology equipment (ITE) processes within the DCN. These metrics are acknowledged as subset of the major metrics of power usage effectiveness (PUE) and data center infrastructure efficiency (DCIE), known to DCs. This study suggests that despite in overall FT consumes more energy, it spends less energy for transmission of a single bit of information, outperforming 3T