A study of large flow interactions in high-speed shared networks with Grid5000 and GtrcNET-10 instruments

We consider the problem of huge data transfers and bandwidth sharing in contexts where transfer delay bounds are required. This report investigates large flow interactions in a real very high-speed network and aims at contributing to high-speed TCP variants evaluation by providing precise measurements. It then also gives an insight on the behaviour of emulated alternative protocols under different realistic congestion and long latency conditions in 10~Gbps experimental environments

Analytical solutions for black-hole critical behaviour

Dynamical Einstein cluster is a spherical self-gravitating system of counterrotating particles, which may expand, oscillate and collapse. This system exhibits critical behaviour in its collapse at the threshold of black hole formation. It appears when the specific angular momentum of particles is tuned finely to the critical value. We find the unique exact self-similar solution at the threshold. This solution begins with a regular surface, involves timelike naked singularity formation and asymptotically approaches a static self-similar cluster.Comment: 4 pages, 3 figures, accepted for publication in General Relativity and Gravitation, typos correcte

Investigation of Ethernet switches behavior in presence of contending flows at very high-speed

This paper examines the interactions between layer 2 (Ethernet) switches and TCP in high bandwidth delay product networks. First, the behavior of a range of Ethernet switches when two long lived connections compete for the same output port is investigated. Then, the report explores the impact of these behaviors on TCP protocol in long and fast networks (LFNs). Several conditions in which scheduling mechanisms introduce heavy unfair bandwidth sharing and loss burst which impact TCP performance are shown

A novel superior factor widely controlling the rice grain quality

Synthesis of storage starch and protein accumulation is the main action of endosperm organogenesis in term of the economic importance of rice. This event is strongly disturbed by abiotic stresses such as high temperature; thus, the upcoming global warming will cause a crisis with a great impact on food production^1,2^. The enzymes for the protein storage and starch synthesis pathway should work in concert to carry out the organogenesis of rice endosperm^3-5^, but the regulatory mechanism is largely unknown. Here we show that a novel regulatory factor, named OsCEO1, acts as the conductor of endosperm organogenesis during the rice grain filling stage. The physiological properties of _floury-endosperm-2_ (_flo2_) mutants showed many similarities to symptoms of grains developed under high-temperature conditions, suggesting important roles of the responsible gene in sensitivity to high-temperature stress. Our map-based cloning identified the responsible gene for the _flo2_ mutant, _OsCEO1_, which has no homology to any genes of known function. The _OsCEO1_ belongs to a novel conserved gene family and encodes a protein composed of 1,720 amino acid residues containing a TPR (tetratricopeptide repeat) motif, which is considered to mediate a protein-protein interaction. The yeast two-hybrid analysis raised an unknown protein showing homology to a late embryogenesis abundant protein and a putative basic helix-loop-helix protein as candidates for the direct interactor for _OsCEO1_, whereas no enzyme genes for the synthesis of storage substances were detected. The _flo2_ mutant exhibited reduced expression of several genes for putative regulatory proteins as well as many enzymes involved in storage starch and proteins. These results suggest that _OsCEO1_ is a superior conductor of the novel regulatory cascade of endosperm organogenesis and may have important roles in the response to high-temperature stress

Large Scale Gigabit Emulated Testbed for Grid Transport Evaluation

International audienceEvaluating the performance of Grid applications running on high performance platforms interconnected by high speed and long distance net- works with new transport services and protocols is highly required. This paper presents the eWAN inte- grated environment enabling large scale grid emula- tion at gigabit speed. It discusses features provided to control key characteristics (topology, round trip time, packet size, drop rate, link capacity) of an evaluation scenario. A method to increase the accuracy of rate control under various delay configuration is proposed and some experimental results are detailled

Design and Implementation of a Local Scheduling System with Advance Reservation for Co-allocation on the Grid

While advance reservation is an essential capability for co-allocating several resources on Grid environments, it is not obvious how it can co-exist with priority-based First Come First Served scheduling, that is widely used as lo-cal scheduling policy today. To investigate this problem, we 1) developed a scheduling API in Java for TORQUE, a variant of OpenPBS, that enables users to implement their own schedulers and replace the original scheduling module with them, 2) implemented a prototype scheduler module that has advance reservation capability with the API. We also provide an external interface for the reservation capa-bility based on WSRF to enable co-allocation of resources over the Grid. Using this interface with the job submission module from Globus toolkit 4, users can make reservation for resources and submit jobs over the Grid

Relativistic Gravitational Collapse of a Cylindrical Shell of Dust

The gravitational collapse of a thick cylindrical shell of dust matter is investigated. It is found that a spacetime singularity forms on the symmetry axis and that it is necessarily naked, i.e., observable in principle. We propose a physically reasonable boundary condition at this naked singularity to construct the solution including its causal future. This boundary condition enables us to construct the unique continuation of spacetime beyond the naked singularity and ensures that the dust shell passes through the naked singularity. When the cylindrical shell leaves its symmetry axis away, the naked singularity disappears, and regularity is recovered. We construct numerical solutions with this feature. This result implies that the gravity produced by a thick cylindrical shell of dust is too weak to bind the shell even if it engenders the formation of a curvature singularity which is so strong as to satisfy the limiting focusing condition. For this reason, this naked singularity is very weak in the extended spacetime; the metric tensor is $C^{1-}$ even at the naked singularity, and the extended spacetime is complete for almost all geodesics. This feature is also seen for singular hypersurfaces. Such an extended spacetime can be regarded as phenomenological in the sense that it is valid if the relevant microphysics length scale is sufficiently small compared to the scale of interest.Comment: 32 pages, 6 figure

The Japanese space gravitational wave antenna; DECIGO

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry– Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre- DECIGO first and finally DECIGO in 2024

DECIGO pathfinder

DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) which is a future space gravitational wave antenna. DECIGO is expected to provide us fruitful insights into the universe, in particular about dark energy, a formation mechanism of supermassive black holes, and the inflation of the universe. Since DECIGO will be an extremely large mission which will formed by three drag-free spacecraft with 1000m separation, it is significant to gain the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. The conceptual design and current status of the first milestone mission, DPF, are reviewed in this article