192,047 research outputs found
Entanglement, intractability and no-signaling
We consider the problem of deriving the no-signaling condition from the
assumption that, as seen from a complexity theoretic perspective, the universe
is not an exponential place. A fact that disallows such a derivation is the
existence of {\em polynomial superluminal} gates, hypothetical primitive
operations that enable superluminal signaling but not the efficient solution of
intractable problems. It therefore follows, if this assumption is a basic
principle of physics, either that it must be supplemented with additional
assumptions to prohibit such gates, or, improbably, that no-signaling is not a
universal condition. Yet, a gate of this kind is possibly implicit, though not
recognized as such, in a decade-old quantum optical experiment involving
position-momentum entangled photons. Here we describe a feasible modified
version of the experiment that appears to explicitly demonstrate the action of
this gate. Some obvious counter-claims are shown to be invalid. We believe that
the unexpected possibility of polynomial superluminal operations arises because
some practically measured quantum optical quantities are not describable as
standard quantum mechanical observables.Comment: 17 pages, 2 figures (REVTeX 4
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View-dependent adaptive cloth simulation
This paper describes a method for view-dependent cloth simulation using dynamically adaptive mesh refinement and coarsening. Given a prescribed camera motion, the method adjusts the criteria controlling refinement to account for visibility and apparent size in the camera's view. Objectionable dynamic artifacts are avoided by anticipative refinement and smoothed coarsening. This approach preserves the appearance of detailed cloth throughout the animation while avoiding the wasted effort of simulating details that would not be discernible to the viewer. The computational savings realized by this method increase as scene complexity grows, producing a 2× speed-up for a single character and more than 4× for a small group
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Information visualization for mobile devices: A novel approach based on the MagicEyeView
Visualization on mobile devices not only means
accommodating to a small screen space, but also
widely different aspect ratios. Improving on the
MagicEyeView algorithm, this paper presents a
visualization technique that is better suited to screens with skewed aspects ratios. The presented approach is a focus+context visualization effort which employs distortion of coordinate scales and a "fisheye" technique. The visualization algorithm is evaluated in the problem domain of business management and the presentation of "Key Performance Indicators"
Extremely broadband ultralight thermally emissive metasurfaces
We report the design, fabrication and characterization of ultralight highly
emissive metaphotonic structures with record-low mass/area that emit thermal
radiation efficiently over a broad spectral (2 to 35 microns) and angular (0-60
degrees) range. The structures comprise one to three pairs of alternating
nanometer-scale metallic and dielectric layers, and have measured effective 300
K hemispherical emissivities of 0.7 to 0.9. To our knowledge, these structures,
which are all subwavelength in thickness are the lightest reported metasurfaces
with comparable infrared emissivity. The superior optical properties, together
with their mechanical flexibility, low outgassing, and low areal mass, suggest
that these metasurfaces are candidates for thermal management in applications
demanding of ultralight flexible structures, including aerospace applications,
ultralight photovoltaics, lightweight flexible electronics, and textiles for
thermal insulation
Movement around real and virtual cluttered environments
Two experiments investigated participants’ ability to search for targets in a cluttered small-scale space. The first experiment was conducted in the real world with two field of view conditions (full vs. restricted), and participants found the task trivial to perform in both. The second experiment used the same search task but was conducted in a desktop virtual environment (VE), and investigated two movement interfaces and two visual scene conditions. Participants restricted to forward only movement performed the search task quicker and more efficiently (visiting fewer targets) than those who used an interface that allowed more flexible movement (forward, backward, left, right, and diagonal). Also, participants using a high fidelity visual scene performed the task significantly quicker and more efficiently than those who used a low fidelity scene. The performance differences between all the conditions decreased with practice, but the performance of the best VE group approached that of the real-world participants. These results indicate the importance of using high fidelity scenes in VEs, and suggest that the use of a simple control system is sufficient for maintaining ones spatial orientation during searching
Movement around real and virtual cluttered environments
Two experiments investigated participants’ ability to search for targets in a cluttered small-scale space. The first experiment was conducted in the real world with two field of view conditions (full vs. restricted), and participants found the task trivial to perform in both. The second experiment used the same search task but was conducted in a desktop virtual environment (VE), and investigated two movement interfaces and two visual scene conditions. Participants restricted to forward only movement performed the search task quicker and more efficiently (visiting fewer targets) than those who used an interface that allowed more flexible movement (forward, backward, left, right, and diagonal). Also, participants using a high fidelity visual scene performed the task significantly quicker and more efficiently than those who used a low fidelity scene. The performance differences between all the conditions decreased with practice, but the performance of the best VE group approached that of the real-world participants. These results indicate the importance of using high fidelity scenes in VEs, and suggest that the use of a simple control system is sufficient for maintaining ones spatial orientation during searching
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