34,113 research outputs found
Is the Web ready for HTTP/2 Server Push?
HTTP/2 supersedes HTTP/1.1 to tackle the performance challenges of the modern
Web. A highly anticipated feature is Server Push, enabling servers to send data
without explicit client requests, thus potentially saving time. Although
guidelines on how to use Server Push emerged, measurements have shown that it
can easily be used in a suboptimal way and hurt instead of improving
performance. We thus tackle the question if the current Web can make better use
of Server Push. First, we enable real-world websites to be replayed in a
testbed to study the effects of different Server Push strategies. Using this,
we next revisit proposed guidelines to grasp their performance impact. Finally,
based on our results, we propose a novel strategy using an alternative server
scheduler that enables to interleave resources. This improves the visual
progress for some websites, with minor modifications to the deployment. Still,
our results highlight the limits of Server Push: a deep understanding of web
engineering is required to make optimal use of it, and not every site will
benefit.Comment: More information available at https://push.netray.i
One-side forward-backward asymmetry at the LHC
Forward-backward asymmetry is an essential observable to study
the nature of coupling in the standard model and physics beyond the standard
model, as shown at LEP and Tevatron. As a proton-proton collider, the LHC does
not have the preferred direction contrary to her counterpart, namely, LEP and
Tevatron. Therefore is not applicable at the LHC. However for the
proton the momentum of valence quark is usually larger than that of the sea
quark. Utilizing this feature we have defined a so-called one-side
forward-backward asymmetry for the top quark pair production at
LHC in the previous work. In this paper we extend our studies to the charged
leptons and bottom quarks as the final states. Our numerical results show that
at the LHC can be utilized to study the nature of the couplings
once enough events are collected.Comment: 19 pages, 7 figures, 1 table, published versio
Hydrodynamic slip boundary condition at chemically patterned surfaces: A continuum deduction from molecular dynamics
We investigate the slip boundary condition for single-phase flow past a
chemically patterned surface. Molecular dynamics (MD) simulations show that
modulation of fluid-solid interaction along a chemically patterned surface
induces a lateral structure in the fluid molecular organization near the
surface. Consequently, various forces and stresses in the fluid vary along the
patterned surface. Given the presence of these lateral variations, a general
scheme is developed to extract hydrodynamic information from MD data. With the
help of this scheme, the validity of the Navier slip boundary condition is
verified for the chemically patterned surface, where a local slip length can be
defined. Based on the MD results, a continuum hydrodynamic model is formulated
using the Navier-Stokes equation and the Navier boundary condition, with a slip
length varying along the patterned surface. Steady-state velocity fields from
continuum calculations are in quantitative agreement with those from MD
simulations. It is shown that, when the pattern period is sufficiently small,
the solid surface appears to be homogeneous, with an effective slip length that
can be controlled by surface patterning. Such a tunable slip length may have
important applications in nanofluidics.Comment: 41 pages, 17 figure
Positive mass theorems for asymptotically AdS spacetimes with arbitrary cosmological constant
We formulate and prove the Lorentzian version of the positive mass theorems
with arbitrary negative cosmological constant for asymptotically AdS
spacetimes. This work is the continuation of the second author's recent work on
the positive mass theorem on asymptotically hyperbolic 3-manifolds.Comment: 17 pages, final version, to appear in International Journal of
Mathematic
Dynamical study of the possible molecular state X(3872) with the s-channel one gluon exchange interaction
The recently observed X(3872) resonance, which is difficult to be assigned a
conventional charmonium state in the quark model, may be interpreted
as a molecular state. Such a molecular state is a hidden flavor four quark
state because of its charmonium-like quantum numbers. The s-channel one gluon
exchange is an interaction which only acts in the hidden flavor multi-quark
system. In this paper, we will study the X(3872) and other similiar hidden
flavor molecular states in a quark model by taking into account of the
s-channel one gluon exchange interaction
Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with suppressed superconductivity in LiFeCoAs
A series of LiFeCoAs compounds with different Co concentrations
have been studied by transport, optical spectroscopy, angle-resolved
photoemission spectroscopy and nuclear magnetic resonance. We observed a Fermi
liquid to non-Fermi liquid to Fermi liquid (FL-NFL-FL) crossover alongside a
monotonic suppression of the superconductivity with increasing Co content. In
parallel to the FL-NFL-FL crossover, we found that both the low-energy spin
fluctuations and Fermi surface nesting are enhanced and then diminished,
strongly suggesting that the NFL behavior in LiFeCoAs is induced
by low-energy spin fluctuations which are very likely tuned by Fermi surface
nesting. Our study reveals a unique phase diagram of LiFeCoAs
where the region of NFL is moved to the boundary of the superconducting phase,
implying that they are probably governed by different mechanisms.Comment: 10 pages, 11 figure
decays in the pQCD approach
We calculate the CP averaged branching ratios and CP-violating asymmetries
for and
decays in the perturbative QCD (pQCD) approach here. The pQCD predictions for
the CP-averaged branching ratios are Br(B_s^0 \to \eta \eta) = \left
(14.2^{+18.0}_{-7.5}) \times 10^{-6}, Br(B_s^0 \to \eta \eta^\prime)= \left
(12.4 ^{+18.2}_{-7.0}) \times 10^{-6}, and Br(B_s^0 \to \eta^{\prime}
\eta^{\prime}) = \left (9.2^{+15.3}_{-4.9}) \times 10^{-6}, which agree well
with those obtained by employing the QCD factorization approach and also be
consistent with available experimental upper limits. The gluonic contributions
are small in size: less than 7% for and
decays, and around 18% for decay. The CP-violating
asymmetries for three decays are very small: less than 3% in magnitude.Comment: 11 pages, 1 ps figure, Revte
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