P2P assisted streaming for low popularity VoD contents

The Video on Demand (VoD) service is becoming a dominant service in the telecommunication market due to the great convenience regarding the choice of content items and their independent viewing time. However, due to its high traffic demand nature, the VoD streaming systems are faced with the problem of huge amounts of traffic generated in the core of the network, especially for serving the requests for content items that are not in the top popularity range. Therefore, we propose a peer assisted VoD model that takes advantage of the clients unused uplink and storage capacity to serve requests for less popular items with the objective to keep the traffic on the periphery of the network, reduce the transport cost in the core of the network and make the system more scalable

Analysis of White Dwarfs with Strange-Matter Cores

We summarize masses and radii for a number of white dwarfs as deduced from a combination of proper motion studies, Hipparcos parallax distances, effective temperatures, and binary or spectroscopic masses. A puzzling feature of these data is that some stars appear to have radii which are significantly smaller than that expected for a standard electron-degenerate white-dwarf equations of state. We construct a projection of white-dwarf radii for fixed effective mass and conclude that there is at least marginal evidence for bimodality in the radius distribution forwhite dwarfs. We argue that if such compact white dwarfs exist it is unlikely that they contain an iron core. We propose an alternative of strange-quark matter within the white-dwarf core. We also discuss the impact of the so-called color-flavor locked (CFL) state in strange-matter core associated with color superconductivity. We show that the data exhibit several features consistent with the expected mass-radius relation of strange dwarfs. We identify eight nearby white dwarfs which are possible candidates for strange matter cores and suggest observational tests of this hypothesis.Comment: 11 pages, 6 figures, accepted for publication in J. Phys. G: Nucl. Part. Phy

Skills Learning in Robot-Assisted Surgery Is Benefited by Task-Specific Augmented Feedback

Background: Providing augmented visual feedback is one way to enhance robot-assisted surgery (RAS) training. However, it is unclear whether task specificity should be considered when applying augmented visual feedback. Methods: Twenty-two novice users of the da Vinci Surgical System underwent testing and training in 3 tasks: simple task, bimanual carrying (BC); intermediate task, needle passing (NP); and complex task, suture tying (ST). Pretraining (PRE), training, and posttraining (POST) trials were performed during the first session. Retention trials were performed 2 weeks later (RET). Participants were randomly assigned to 1 of 4 feedback training groups: relative phase (RP), speed, grip force, and video feedback groups. Performance measures were time to task completion (TTC), total distance traveled (D), speed (S), curvature, relative phase, and grip force (F). Results: Significant interaction for TTC and curvature showed that the RP feedback training improved temporal measures of complex ST task compared to simple BC task. Speed feedback training significantly improved the performance in simple BC task in terms of TTC, D, S, curvature, and F even after retention. There was also a lesser long-term effect of speed feedback training on complex ST task. Grip force feedback training resulted in significantly greater improvements in TTC and curvature for complex ST task. For the video feedback training group, the improvements in most of the outcome measures were evident only after RET. Conclusions: Task-specific augmented feedback is beneficial to RAS skills learning. Particularly, the RP and grip force feedback could be useful for training complex tasks

Finite temperature effects on cosmological baryon diffusion and inhomogeneous Big-Bang nucleosynthesis

We have studied finite temperature corrections to the baryon transport cross sections and diffusion coefficients. These corrections are based upon the recently computed renormalized electron mass and the modified state density due to the background thermal bath in the early universe. It is found that the optimum nucleosynthesis yields computed using our diffusion coefficients shift to longer distance scales by a factor of about 3. We also find that the minimum value of $^4 He$ abundance decreases by $\Delta Y_p \simeq 0.01$ while $D$ and $^7 Li$ increase. Effects of these results on constraints from primordial nucleosynthesis are discussed. In particular, we find that a large baryonic contribution to the closure density (\Omega_b h_{50}^{2} \lsim 0.4) may be allowed in inhomogeneous models corrected for finite temperature.Comment: 7 pages, 6 figures, submitted to Phys. Rev.

Bremsstrahlung photon polarization for ee±→(eγ)e±ee^\pm\to (e\gamma)e^\pm, and ep→(eγ)pep\to (e\gamma)p high energy collisions

The polarization of bremsstrahlung photon in the processes $ee^\pm\to (e\gamma)e^\pm$, and $ep\to (e\gamma)p$ is calculated for peripheral kinematics, in the high energy limit where the cross section does not decrease with the incident energy. When the initial electron is unpolarized(longitudinally polarized) the final photon can be linearly (circularly) polarized. The Stokes parameters of the photon polarization are calculated as a function of the kinematical variables of process: the energy of recoil particle, the energy fraction of scattered electron, and the polar and azimuthal angles of photon. Numerical results are given in form of tables, for typical values of the relevant kinematic variables.Comment: 9 pages, 3 figure

Study of the neutron star structure in strong magnetic fields including the anomalous magnetic moments

We study the effects of strong magnetic fields on the neutron star structure. If the interior field of a star is on the same order of the surface field currently observed, the influences of the magnetic field on the star mass and radius are negligible. If one assumes that the internal magnetic field can be as large as that estimated from the scalar virial theorem, considerable effects can be induced. The maximum mass of stars is arisen substantially while the central density is largely suppressed. For two equal-mass stars the radius of the magnetic star can be larger by about 10% $\sim$ 20% than the nonmagnetic star.Comment: 26 pages, 5 postscript figures; replaced by the revised version, Chin. J. Astron. Astrophys., accepte