8,737 research outputs found
"If You Can't Beat them, Join them": A Usability Approach to Interdependent Privacy in Cloud Apps
Cloud storage services, like Dropbox and Google Drive, have growing
ecosystems of 3rd party apps that are designed to work with users' cloud files.
Such apps often request full access to users' files, including files shared
with collaborators. Hence, whenever a user grants access to a new vendor, she
is inflicting a privacy loss on herself and on her collaborators too. Based on
analyzing a real dataset of 183 Google Drive users and 131 third party apps, we
discover that collaborators inflict a privacy loss which is at least 39% higher
than what users themselves cause. We take a step toward minimizing this loss by
introducing the concept of History-based decisions. Simply put, users are
informed at decision time about the vendors which have been previously granted
access to their data. Thus, they can reduce their privacy loss by not
installing apps from new vendors whenever possible. Next, we realize this
concept by introducing a new privacy indicator, which can be integrated within
the cloud apps' authorization interface. Via a web experiment with 141
participants recruited from CrowdFlower, we show that our privacy indicator can
significantly increase the user's likelihood of choosing the app that minimizes
her privacy loss. Finally, we explore the network effect of History-based
decisions via a simulation on top of large collaboration networks. We
demonstrate that adopting such a decision-making process is capable of reducing
the growth of users' privacy loss by 70% in a Google Drive-based network and by
40% in an author collaboration network. This is despite the fact that we
neither assume that users cooperate nor that they exhibit altruistic behavior.
To our knowledge, our work is the first to provide quantifiable evidence of the
privacy risk that collaborators pose in cloud apps. We are also the first to
mitigate this problem via a usable privacy approach.Comment: Authors' extended version of the paper published at CODASPY 201
Fermi liquid features of the one-dimensional Luttinger liquid
We show that the one-dimensional (1D) electron systems can also be described
by Landau's phenomenological Fermi-liquid theory. Most of the known results
derived from the Luttinger-liquid theory can be retrieved from the 1D
Fermi-liquid theory.
Exact correspondence between the Landau parameters and Haldane parameters is
established. The exponents of the dynamical correlation functions and the
impurity problem are also discussed based on the finite size corrections of
elementary excitations with the predictions of the conformal field theory,
which provides a bridge between the 1D Fermi-liquid and the Luttinger liquid.Comment: RevTeX, 5 pages, published versio
A consistent description of kinetic equation with triangle anomaly
We provide a consistent description of the kinetic equation with triangle
anomaly which is compatible with the entropy principle of the second law of
thermodynamics and the charge/energy-momentum conservation equations. In
general an anomalous source term is necessary to ensure that the equations for
the charge and energy-momentum conservation are satisfied and that the
correction terms of distribution functions are compatible to these equations.
The constraining equations from the entropy principle are derived for the
anomaly-induced leading order corrections to the particle distribution
functions. The correction terms can be determined for minimum number of unknown
coefficients in one charge and two charge cases by solving the constraining
equations.Comment: RevTex 4, 11 pages; With minor changes: typos are corrected and one
reference is added. Accepted version to PR
Wave mixing of optical pulses and Bose-Einstein condensates
We investigate theoretically the four-wave mixing of optical and matter waves
resulting from the scattering of a short light pulse off an atomic
Bose-Einstein condensate, as recently demonstrated by D. Schneble {\em et al.}
[ Science {\bf 300}, 475 (2003)]. We show that atomic ``pair production'' from
the condensate results in the generation of both forward- and
backward-propagating matter waves. These waves are characterized by different
phase-matching conditions, resulting in different angular distributions and
temporal evolutions.Comment: 4+\epsilon pages, 3 figure
Spontaneous spin textures in dipolar spinor condensates
We have mapped out a detailed phase diagram that shows the ground state
structure of a spin-1 condensate with magnetic dipole-dipole interactions. We
show that the interplay between the dipolar and the spin-exchange interactions
induces a rich variety of quantum phases that exhibit spontaneous magnetic
ordering in the form of intricate spin textures.Comment: 4.1 pages, 4 figure
Excitation spectrum and instability of a two-species Bose-Einstein condensate
We numerically calculate the density profile and excitation spectrum of a
two-species Bose-Einstein condensate for the parameters of recent experiments.
We find that the ground state density profile of this system becomes unstable
in certain parameter regimes, which leads to a phase transition to a new stable
state. This state displays spontaneously broken cylindrical symmetry. This
behavior is reflected in the excitation spectrum: as we approach the phase
transition point, the lowest excitation frequency goes to zero, indicating the
onset of instability in the density profile. Following the phase transition,
this frequency rises again.Comment: 8 pages, 5 figures, uses REVTe
Physiological Electrical Signals Promote Chain Migration of Neuroblasts by Up-Regulating P2Y1 Purinergic Receptors and Enhancing Cell Adhesion
Acknowledgments This work was supported by a grant from NHS Grampian. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are creditedPeer reviewedPublisher PD
Does stability of relativistic dissipative fluid dynamics imply causality?
We investigate the causality and stability of relativistic dissipative fluid
dynamics in the absence of conserved charges. We perform a linear stability
analysis in the rest frame of the fluid and find that the equations of
relativistic dissipative fluid dynamics are always stable. We then perform a
linear stability analysis in a Lorentz-boosted frame. Provided that the ratio
of the relaxation time for the shear stress tensor, , to the sound
attenuation length, , fulfills a certain
asymptotic causality condition, the equations of motion give rise to stable
solutions. Although the group velocity associated with perturbations may exceed
the velocity of light in a certain finite range of wavenumbers, we demonstrate
that this does not violate causality, as long as the asymptotic causality
condition is fulfilled. Finally, we compute the characteristic velocities and
show that they remain below the velocity of light if the ratio
fulfills the asymptotic causality condition.Comment: 30 pages, 10 figures
Half-quantum vortex state in a spin-orbit coupled Bose-Einstein condensate
We investigate theoretically the condensate state and collective excitations
of a two-component Bose gas in two-dimensional harmonic traps subject to
isotropic Rashba spin-orbit coupling. In the weakly interacting regime when the
inter-species interaction is larger than the intra-species interaction
(), we find that the condensate ground state has a
half-quantum-angular-momentum vortex configuration with spatial rotational
symmetry and skyrmion-type spin texture. Upon increasing the interatomic
interaction beyond a threshold , the ground state starts to involve
higher-order angular momentum components and thus breaks the rotational
symmetry. In the case of , the condensate becomes
unstable towards the superposition of two degenerate half-quantum vortex
states. Both instabilities (at and ) can be
determined by solving the Bogoliubov equations for collective density
oscillations of the half-quantum vortex state, and by analyzing the softening
of mode frequencies. We present the phase diagram as functions of the
interatomic interactions and the spin-orbit coupling. In addition, we directly
simulate the time-dependent Gross-Pitaevskii equation to examine the dynamical
properties of the system. Finally, we investigate the stability of the
half-quantum vortex state against both the trap anisotropy and anisotropy in
the spin-orbit coupling term.Comment: 13 pages, 18 figure
Modulational instability in a layered Kerr medium: Theory and Experiment
We present the first experimental investigation of modulational instability
in a layered Kerr medium. The particularly interesting and appealing feature of
our configuration, consisting of alternating glass-air layers, is the
piecewise-constant nature of the material properties, which allows a
theoretical linear stability analysis leading to a Kronig-Penney equation whose
forbidden bands correspond to the modulationally unstable regimes. We find very
good {\it quantitative} agreement between theoretical, numerical, and
experimental diagnostics of the modulational instability. Because of the
periodicity in the evolution variable arising from the layered medium, there
are multiple instability regions rather than just one as in the uniform medium.Comment: 4 pages, 4 figures, contains experimental + computational +
theoretical results, to appear in Physical Review Letter
- …