3,751 research outputs found
Subalgebra-subregion duality: emergence of space and time in holography
In holographic duality, a higher dimensional quantum gravity system emerges
from a lower dimensional conformal field theory (CFT) with a large number of
degrees of freedom. We propose a formulation of duality for a general causally
complete bulk spacetime region, called subalgebra-subregion duality, which
provides a framework to describe how geometric notions in the gravity system,
such as spacetime subregions, different notions of times, and causal structure,
emerge from the dual CFT. Subalgebra-subregion duality generalizes and brings
new insights into subregion-subregion duality (or equivalently entanglement
wedge reconstruction). It provides a mathematically precise definition of
subregion-subregion duality and gives an independent definition of entanglement
wedges without using entropy. Geometric properties of entanglement wedges,
including those that play a crucial role in interpreting the bulk as a quantum
error correcting code, can be understood from the duality as the geometrization
of the additivity anomaly of certain algebras. Using general boundary
subalgebras rather than those associated with geometric subregions makes it
possible to find duals for general bulk spacetime regions, including those not
touching the boundary. Applying subalgebra-subregion duality to a boundary
state describing a single-sided black hole also provides a precise way to
define mirror operators.Comment: 104 pages, 29 figure
Developing interest to share and craft based on the Technology Acceptance Model
The Malaysian Ministry of Education aims to increase interest in learning Science, Technology, Engineering and Mathematics, through Science2Action. Among these
initiatives in Science2Action, is the use of Art(s). By
combining the Internet, technology and crafts, e-crafting
is formed. This e-crafting project aims to increase
awareness about what interests the audience through
sharing of and development of craft, hopefully towards
possibilities of ideation and mixing crafts, extending
from the original craft such as origami. Designed based
on the Technology Acceptance Model, findings are
positive
Development of the MICROMEGAS Detector for Measuring the Energy Spectrum of Alpha Particles by using a 241-Am Source
We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting
{\alpha} particles emitted from an 241-Am standard source. The voltage applied
to the ionization region of the detector is optimized for stable operation at
room temperature and atmospheric pressure. The energy of {\alpha} particles
from the 241-Am source can be varied by changing the flight path of the
{\alpha} particle from the 241 Am source. The channel numbers of the
experimentally-measured pulse peak positions for different energies of the
{\alpha} particles are associated with the energies deposited by the alpha
particles in the ionization region of the detector as calculated by using
GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for
{\alpha} particles is done. For the energy calibration, the thickness of the
ionization region is adjusted so that {\alpha} particles may completely stop in
the ionization region and their kinetic energies are fully deposited in the
region. The efficiency of our MICROMEGAS detector for {\alpha} particles under
the present conditions is found to be ~ 97.3 %
Intracranial glioma xenograft model rapidly reestablishes bloodâbrain barrier integrity for longitudinal imaging of tumor progression using fluorescence molecular tomography and contrast agents
Stochastic particle advection velocimetry (SPAV): theory, simulations, and proof-of-concept experiments
Particle tracking velocimetry (PTV) is widely used to measure time-resolved,
three-dimensional velocity and pressure fields in fluid dynamics research.
Inaccurate localization and tracking of particles is a key source of error in
PTV, especially for single camera defocusing, plenoptic imaging, and digital
in-line holography (DIH) sensors. To address this issue, we developed
stochastic particle advection velocimetry (SPAV): a statistical data loss that
improves the accuracy of PTV. SPAV is based on an explicit particle advection
model that predicts particle positions over time as a function of the estimated
velocity field. The model can account for non-ideal effects like drag on
inertial particles. A statistical data loss that compares the tracked and
advected particle positions, accounting for arbitrary localization and tracking
uncertainties, is derived and approximated. We implement our approach using a
physics-informed neural network, which simultaneously minimizes the SPAV data
loss, a Navier-Stokes physics loss, and a wall boundary loss, where
appropriate. Results are reported for simulated and experimental DIH-PTV
measurements of laminar and turbulent flows. Our statistical approach
significantly improves the accuracy of PTV reconstructions compared to a
conventional data loss, resulting in an average reduction of error close to
50%. Furthermore, our framework can be readily adapted to work with other data
assimilation techniques like state observer, Kalman filter, and
adjoint-variational methods
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