Network Awareness of P2P Live Streaming Applications

Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work. In this paper we present large scale sets of experiments to compare three of the most successful P2P-TV systems, namely PPLive, SopCast and TVAnts. Our goal is to assess what level of "network awareness" has been embedded in the applications, i.e., what parameters mainly drive the peer selection and data exchange. By using a general framework that can be extended to other systems and metrics, we show that all applications largely base their choices on the peer bandwidth, i.e., they prefer high-bandwidth users, which is rather intuitive. Moreover, TVAnts and PPLive exhibits also a preference to exchange data among peers in the same autonomous system the peer belongs to. However, no evidence about preference versus peers in the same subnet or that are closer to the considered peer emerges. We believe that next-generation P2P live streaming applications definitively need to improve the level of network-awareness, so to better localize the traffic in the network and thus increase their network-friendliness as wel

The OLYMPUS Internal Hydrogen Target

An internal hydrogen target system was developed for the OLYMPUS experiment at DESY, in Hamburg, Germany. The target consisted of a long, thin-walled, tubular cell within an aluminum scattering chamber. Hydrogen entered at the center of the cell and exited through the ends, where it was removed from the beamline by a multistage pumping system. A cryogenic coldhead cooled the target cell to counteract heating from the beam and increase the density of hydrogen in the target. A fixed collimator protected the cell from synchrotron radiation and the beam halo. A series of wakefield suppressors reduced heating from beam wakefields. The target system was installed within the DORIS storage ring and was successfully operated during the course of the OLYMPUS experiment in 2012. Information on the design, fabrication, and performance of the target system is reported.Comment: 9 pages, 13 figure

The LHCspin project

The LHCspin project aims to bring both unpolarized and polarized physics at the LHC through the installation of a gaseous fixed target at the upstream end of the LHCb detector. The forward geometry of the LHCb spectrometer (2 < η < 5) is perfectly suited for the reconstruction of particles produced in fixed-target collisions. The fixed-target configuration, with center-of-mass energies ranging from √sNN = 72 GeV in collisions with Pb beams to √s = 115 GeV in pp interactions, allows to cover a wide backward center-of-mass rapidity region, corresponding to the poorly explored high x-Bjorken and high x-Feynman regimes. The project has several ambitious goals regarding heavy-ion physics and new-era quantitative searches in QCD through the study of the nucleon's internal dynamics in terms of both quarks and gluons degrees of freedom. In particular, the use of transversely polarized H and D targets will allow to study the quarks TMDs in pp collisions at unique kinematic conditions. Furthermore, being LHCb specifically designed for heavy-flavor physics, final states with c- or b-quarks (e.g. inclusive quarkonia production) will be efficiently reconstructed, thus providing, among other fundamental measurememnts, access to the so-far unknown gluons TMDs. The status of the project is presented along with a selection of physics opportunities

Network Awareness of P2P Live Streaming Applications: A Measurement Study

Abstract: Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work, due to their closed and proprietary design. In this paper, we present large scale experiments to compare three of the most successful P2P-TV systems, namely PPLive, SopCast and TVAnts. Our goal is to assess what level of "network awareness" has been embedded in the applications. We first define a general framework to quantify which network layer parameters leverage application choices, i.e., what parameters mainly drive the peer selection and data exchange. We then apply the methodology to a large dataset, collected during a number of experiments where we deployed about 40 peers in several European countries. From analysis of the dataset, we observe that TVAnts and PPLive exhibit a mild preference to exchange data among peers in the same autonomous system the peer belongs to, while this clustering effect is less intense in SopCast. However, no preference versus country, subnet or hop count is shown. Therefore, we believe that next-generation P2P live streaming applications definitively need to improve the level of network-awareness, so to better localize the traffic in the network and thus increase their network-friendliness as well

Age- and sex-related variations in platelet count in Italy: a proposal of reference ranges based on 40987 subjects' data

BACKGROUND AND OBJECTIVES: Although several studies demonstrated that platelet count is higher in women, decreases with age, and is influenced by genetic background, most clinical laboratories still use the reference interval 150-400×10(9) platelets/L for all subjects. The present study was to identify age- and sex-specific reference intervals for platelet count. METHODS: We analysed electronic records of subjects enrolled in three population-based studies that investigated inhabitants of seven Italian areas including six geographic isolates. After exclusion of patients with malignancies, liver diseases, or inherited thrombocytopenias, which could affect platelet count, reference intervals were estimated from 40,987 subjects with the non parametric method computing the 2.5° and 97.5° percentiles. RESULTS: Platelet count was similar in men and women until the age of 14, but subsequently women had steadily more platelets than men. The number of platelets decreases quickly in childhood, stabilizes in adulthood, and further decreases in oldness. The final result of this phenomenon is that platelet count in old age was reduced by 35% in men and by 25% in women compared with early infancy. Based on these findings, we estimated reference intervals for platelet count ×10(9)/L in children (176-452), adult men (141-362), adult women (156-405), old men (122-350) and, old women (140-379). Moreover, we calculated an extended reference interval that takes into account the differences in platelet count observed in different geographic areas. CONCLUSIONS: The age-, sex-, and origin-related variability of platelet count is very wide, and the patient-adapted reference intervals we propose change the thresholds for diagnosing both thrombocytopenia and thrombocytosis in Italy

Measuring the Polarization of a Rapidly Precessing Deuteron Beam

This paper describes a time-marking system that enables a measurement of the in-plane (horizontal) polarization of a 0.97-GeV/c deuteron beam circulating in the Cooler Synchrotron (COSY) at the Forschungszentrum J\"ulich. The clock time of each polarimeter event is used to unfold the 120-kHz spin precession and assign events to bins according to the direction of the horizontal polarization. After accumulation for one or more seconds, the down-up scattering asymmetry can be calculated for each direction and matched to a sinusoidal function whose magnitude is proportional to the horizontal polarization. This requires prior knowledge of the spin tune or polarization precession rate. An initial estimate is refined by re-sorting the events as the spin tune is adjusted across a narrow range and searching for the maximum polarization magnitude. The result is biased toward polarization values that are too large, in part because of statistical fluctuations but also because sinusoidal fits to even random data will produce sizeable magnitudes when the phase is left free to vary. An analysis procedure is described that matches the time dependence of the horizontal polarization to templates based on emittance-driven polarization loss while correcting for the positive bias. This information will be used to study ways to extend the horizontal polarization lifetime by correcting spin tune spread using ring sextupole fields and thereby to support the feasibility of searching for an intrinsic electric dipole moment using polarized beams in a storage ring. This paper is a combined effort of the Storage Ring EDM Collaboration and the JEDI Collaboration.Comment: 28 pages, 15 figures, prepared for Physical Review ST - Accelerators and Beam

A bulk superconducting MgB2 cylinder for holding transversely polarized targets

An innovative solution is being pursued for the challenging magnetic problem of producing an internal transverse field around a polarized target, while shielding out an external longitudinal field from a detector. A hollow bulk superconductor can trap a transverse field that is present when cooled through its transition temperature, and also shield its interior from any subsequent field changes. A feasibility study with a prototype bulk MgB2 superconducting cylinder is described. Promising measurements taken of the interior field retention and exterior field exclusion, together with the corresponding long-term stability performance, are reported. In the context of an electron scattering experiment, such a solution minimizes beam deflection and the energy loss of reaction products, while also eliminating the heat load to the target cryostat from current leads that would be used with conventional electromagnets

Toward polarized antiprotons: Machine development for spin-filtering experiments

The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of $49.3\,$MeV in COSY. The implementation of a low-$\beta$ insertion made it possible to achieve beam lifetimes of $\tau_{\rm{b}}=8000\,$s in the presence of a dense polarized hydrogen storage-cell target of areal density $d_{\rm t}=(5.5\pm 0.2)\times 10^{13}\,\mathrm{atoms/cm^{2}}$. The developed techniques can be directly applied to antiproton machines and allow for the determination of the spin-dependent $\bar{p}p$ cross sections via spin filtering

Phase Measurement for Driven Spin Oscillations in a Storage Ring

This paper reports the first simultaneous measurement of the horizontal and vertical components of the polarization vector in a storage ring under the influence of a radio frequency (rf) solenoid. The experiments were performed at the Cooler Synchrotron COSY in J\"ulich using a vector polarized, bunched $0.97\,\textrm{GeV/c}$ deuteron beam. Using the new spin feedback system, we set the initial phase difference between the solenoid field and the precession of the polarization vector to a predefined value. The feedback system was then switched off, allowing the phase difference to change over time, and the solenoid was switched on to rotate the polarization vector. We observed an oscillation of the vertical polarization component and the phase difference. The oscillations can be described using an analytical model. The results of this experiment also apply to other rf devices with horizontal magnetic fields, such as Wien filters. The precise manipulation of particle spins in storage rings is a prerequisite for measuring the electric dipole moment (EDM) of charged particles