40,372 research outputs found
Strategic Asset Seeking and Innovation Performance: The Role of Innovation Capabilities and Host Country Institutions
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Neutrino Oscillations and Lepton Flavor Mixing
In view of the recent announcement on non-zero neutrino mass from
Super-Kamiokande experiment, it would be very timely to investigate all the
possible scenarios on masses and mixings of light neutrinos. Recently suggested
mass matrix texture for the quark CKM mixing, which can be originated from the
family permutation symmetry and its suitable breakings, is assumed for the
neutrino mass matrix and determined by the four combinations of solar,
atmospheric and LSND neutrino data and cosmological hot dark matter bound as
input constraints. The charged-lepton mass matrix is assumed to be diagonal so
that the neutrino mixing matrix can be identified directly as the lepton flavor
mixing matrix and no CP invariance violation originates from the leptonic
sector. The results favor hierarchical patterns for the neutrino masses, which
follow from the case when either solar-atmospheric data or solar-HDM
constraints are used.Comment: Latex, 9 page
Separable states and the geometric phases of an interacting two-spin system
It is known that an interacting bipartite system evolves as an entangled
state in general, even if it is initially in a separable state. Due to the
entanglement of the state, the geometric phase of the system is not equal to
the sum of the geometric phases of its two subsystems. However, there may exist
a set of states in which the nonlocal interaction does not affect the
separability of the states, and the geometric phase of the bipartite system is
then always equal to the sum of the geometric phases of its subsystems. In this
paper, we illustrate this point by investigating a well known physical model.
We give a necessary and sufficient condition in which a separable state remains
separable so that the geometric phase of the system is always equal to the sum
of the geometric phases of its subsystems.Comment: 13 page
Graphics processing unit accelerated computation of digital holograms
Cataloged from PDF version of article.An approximation for fast digital hologram generation is implemented on a central processing unit (CPU), a graphics processing unit (GPU), and a multi-GPU computational platform. The computational performance of the method on each platform is measured and compared. The computational speed on the GPU platform is much faster than on a CPU, and the algorithm could be further accelerated on a multi-GPU platform. In addition, the accuracy of the algorithm for single-and double-precision arithmetic is evaluated. The quality of the reconstruction from the algorithm using single-precision arithmetic is comparable with the quality from the double-precision arithmetic, and thus the implementation using single-precision arithmetic on a multi-GPU platform can be used for holographic video displays. (C) 2009 Optical Society of America
Real-time phase-only color holographic video display system using LED illumination
Cataloged from PDF version of article.A real-time full-color phase-only holographic display system generates holograms of 3D objects. The system includes a 3D object formed by voxels, an internet-based transmission capability that transmits the object information to the server, a real-time hologram generation unit, and a holographic display unit with incoherent illumination. The server calculates three phase holograms for RGB components using multiple GPUs. The resultant phase holograms are saved into an RGB bitmap image and loaded to the phase-only spatial light modulators (SLMs). SLMs are illuminated uniformly by LEDs, and reconstructed waves are aligned and overlapped by using high precision optics and stages. Experimental results are satisfactory. © 2009 Optical Society of America
Digital Holographic Three-Dimensional Video Displays
Cataloged from PDF version of article.Holography aims to record and regenerate volume
filling light fields to reproduce ghost-like 3-D images that are
optically indistinguishable from their physical 3-D originals.
Digital holographic video displays are pixelated devices on which
digital holograms can be written at video rates. Spatial light
modulators (SLMs) are used for such purposes in practice; even
though it is desirable to have SLMs that can modulate both the
phase and amplitude of the incident light at each pixel, usually
amplitude-only or phase-only SLMs are available. Many laboratories
have reported working prototypes using different designs.
Size and resolution of the SLMs are quite demanding for
satisfactory 3-D reconstructions. Space–bandwidth product
(SBP) seems like a good metric for quality analysis. Even though
moderate SBP is satisfactory for a stationary observer with no
lateral or rotational motion, the required SBP quickly increases
when such motion is allowed. Multi-SLM designs, especially over
curved surfaces, relieve high bandwidth requirements, and
therefore, are strong candidates for futuristic holographic video
displays. Holograms are quite robust to noise and quantization. It
is demonstrated that either laser or light-emitting diode (LED)
illumination is feasible. Current research momentum is increasing
with many exciting and encouraging results
Circular holographic video display system
Cataloged from PDF version of article.A circular holographic video display system reconstructs
holographic video. Phase-only spatial light modulators are tiled in a circular
configuration in order to increase the field of view. A beam-splitter is used
to align the active area of the SLMs side by side without any gap. With the
help of this configuration observers can see 3D ghost-like image floating in
space and can move and rotate around the object. The 3D reconstructions can be observed binocularly. Experimental results are satisfactory. © 2011 Optical Society of Americ
A Comparison between the Zero Forcing Number and the Strong Metric Dimension of Graphs
The \emph{zero forcing number}, , of a graph is the minimum
cardinality of a set of black vertices (whereas vertices in are
colored white) such that is turned black after finitely many
applications of "the color-change rule": a white vertex is converted black if
it is the only white neighbor of a black vertex. The \emph{strong metric
dimension}, , of a graph is the minimum among cardinalities of all
strong resolving sets: is a \emph{strong resolving set} of
if for any , there exists an such that either
lies on an geodesic or lies on an geodesic. In this paper, we
prove that for a connected graph , where is
the cycle rank of . Further, we prove the sharp bound
when is a tree or a unicyclic graph, and we characterize trees
attaining . It is easy to see that can be
arbitrarily large for a tree ; we prove that and
show that the bound is sharp.Comment: 8 pages, 5 figure
HIV-1 Tat exacerbates lipopolysaccharide-induced cytokine release via TLR4 signaling in the enteric nervous system
The loss of gut epithelium integrity leads to translocation of microbes and microbial products resulting in immune activation and drives systemic inflammation in acquired immunodeficiency syndrome (AIDS) patients. Although viral loads in HIV patients are significantly reduced in the post-cART era, inflammation and immune activation persist and can lead to morbidity. Here, we determined the interactive effects of the viral protein HIV-1 Tat and lipopolysaccharide (LPS) on enteric neurons and glia. Bacterial translocation was significantly enhanced in Tat-expressing (Tat+) mice. Exposure to HIV-1 Tat in combination with LPS enhanced the expression and release of the pro-inflammatory cytokines IL-6, IL-1β and TNF-α in the ilea of Tat+ mice and by enteric glia. This coincided with enhanced NF-κB activation in enteric glia that was abrogated in glia from TLR4 knockout mice and by knockdown (siRNA) of MyD88 siRNA in wild type glia. The synergistic effects of Tat and LPS resulted in a reduced rate of colonic propulsion in Tat+ mice treated with LPS. These results show that HIV-1 Tat interacts with the TLR4 receptor to enhance the pro-inflammatory effects of LPS leading to gastrointestinal dysmotility and enhanced immune activation
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