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Spatiotemporal double-phase hologram for complex-amplitude holographic displays
This Letter describes an approach to encode complex-amplitude light waves with spatiotemporal double-phase holograms (DPHs) for overcoming the limit of the space-bandwidth product (SBP) delivered by existing methods. To construct DPHs, two spatially macro-pixel encoded phase components are employed in the SBP-preserved resampling of complex holograms. Four generated sub-DPHs are displayed sequentially in time for high-quality holographic image reconstruction without reducing the image size or discarding any image terms when the DPHs are interweaved. The reconstructed holographic images contain more details and less speckle noise, with their signal-to-noise ratio and structure similarity index being improved by 14.64% and 78.79%, respectively
The Additional Line Component within the Iron K\alpha Profile in MCG-6-30-15: Evidence for Blob Ejection?
The EPIC data of MCG -6-30-15 observed by XMM-Newton were analyzed for the
complexities of the iron K-alpha line. Here we report that the additional line
component (ALC) at 6.9 keV undoubtedly appears within the broad iron Kalpha;
line profile at the high state, whereas it disappears at the low state. These
state-dependent behaviors exclude several possible origins and suggest an
origin of the ALC in matter being ejected from the vicinity of the black hole.
At the low state, the newborn blob ejected from the accretion disk is so
Thomson-thick that hard X-rays are blocked from ionizing the old blobs, leading
to the disappearance of the ALC. When the blob becomes Thomson-thin as a result
of expansion, the hard X-ray will penetrate it and ionize the old ones,
emitting the ALC at the high state. The blob ejection is the key to switching
the ALC on or off.Comment: 6 pages, 4 Figure
Light-Front Quantization and AdS/QCD: An Overview
We give an overview of the light-front holographic approach to strongly
coupled QCD, whereby a confining gauge theory, quantized on the light front, is
mapped to a higher-dimensional anti de Sitter (AdS) space. The framework is
guided by the AdS/CFT correspondence incorporating a gravitational background
asymptotic to AdS space which encodes the salient properties of QCD, such as
the ultraviolet conformal limit at the AdS boundary at , as well as
modifications of the geometry in the large infrared region to describe
confinement and linear Regge behavior. There are two equivalent procedures for
deriving the AdS/QCD equations of motion: one can start from the Hamiltonian
equation of motion in physical space time by studying the off-shell dynamics of
the bound state wavefunctions as a function of the invariant mass of the
constituents. To a first semiclassical approximation, where quantum loops and
quark masses are not included, this leads to a light-front Hamiltonian equation
which describes the bound state dynamics of light hadrons in terms of an
invariant impact variable which measures the separation of the partons
within the hadron at equal light-front time. Alternatively, one can start from
the gravity side by studying the propagation of hadronic modes in a fixed
effective gravitational background. Both approaches are equivalent in the
semiclassical approximation. This allows us to identify the holographic
variable in AdS space with the impact variable . Light-front
holography thus allows a precise mapping of transition amplitudes from AdS to
physical space-time. The internal structure of hadrons is explicitly introduced
and the angular momentum of the constituents plays a key role.Comment: Invited talk presented by GdT at the XIV School of Particles and
Fields, Morelia, Mexico, November 8-12, 201
Status of the QCDSP project
We describe the completed 8,192-node, 0.4Tflops machine at Columbia as well
as the 12,288-node, 0.6Tflops machine assembled at the RIKEN Brookhaven
Research Center. Present performance as well as our experience in commissioning
these large machines is presented. We outline our on-going physics program and
explain how the configuration of the machine is varied to support a wide range
of lattice QCD problems, requiring a variety of machine sizes. Finally a brief
discussion is given of future prospects for large-scale lattice QCD machines.Comment: LATTICE98(machines), 3 pages, 1 picture, 1 figur
An exploratory study of autopilot software bugs in unmanned aerial vehicles
Unmanned aerial vehicles (UAVs) are becoming increasingly important and widely used in modern society. Software bugs in these systems can cause severe issues, such as system crashes, hangs, and undefined behaviors. Some bugs can also be exploited by hackers to launch security attacks, resulting in catastrophic consequences. Therefore, techniques that can help detect and fix software bugs in UAVs are highly desirable. However, although there are many existing studies on bugs in various types of software, the characteristics of UAV software bugs have never been systematically studied. This impedes the development of tools for assuring the dependability of UAVs. To bridge this gap, we conducted the first large-scale empirical study on two well-known open-source autopilot software platforms for UAVs, namely PX4 and Ardupilot, to characterize bugs in UAVs. Through analyzing 569 bugs from these two projects, we observed eight types of UAV-specific bugs (i.e., limit, math, inconsistency, priority, parameter, hardware support, correction, and initialization) and learned their root causes. Based on the bug taxonomy, we summarized common bug patterns and repairing strategies. We further identified five challenges associated with detecting and fixing such UAV-specific bugs. Our study can help researchers and practitioners to better understand the threats to the dependability of UAV systems and facilitate the future development of UAV bug diagnosis tools
Domain wall fermion zero modes on classical topological backgrounds
The domain wall approach to lattice fermions employs an additional dimension,
in which gauge fields are merely replicated, to separate the chiral components
of a Dirac fermion. It is known that in the limit of infinite separation in
this new dimension, domain wall fermions have exact zero modes, even for gauge
fields which are not smooth. We explore the effects of finite extent in the
fifth dimension on the zero modes for both smooth and non-smooth topological
configurations and find that a fifth dimension of around ten sites is
sufficient to clearly show zero mode effects. This small value for the extent
of the fifth dimension indicates the practical utility of this technique for
numerical simulations of QCD.Comment: Updated fig. 3-7, small changes in sect. 3, added fig. 8, added more
reference
P19-50 LB. Role of vaccine-induced innate and adaptive immunity in controlling mucosal transmission of SIV in macaques
Top-gated graphene field-effect-transistors formed by decomposition of SiC
Top-gated, few-layer graphene field-effect transistors (FETs) fabricated on
thermally-decomposed semi-insulating 4H-SiC substrates are demonstrated.
Physical vapor deposited SiO2 is used as the gate dielectric. A two-dimensional
hexagonal arrangement of carbon atoms with the correct lattice vectors,
observed by high-resolution scanning tunneling microscopy, confirms the
formation of multiple graphene layers on top of the SiC substrates. The
observation of n-type and p-type transition further verifies Dirac Fermions
unique transport properties in graphene layers. The measured electron and hole
mobility on these fabricated graphene FETs are as high as 5400 cm2/Vs and 4400
cm2/Vs respectively, which are much larger than the corresponding values from
conventional SiC or silicon
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