10,755 research outputs found
Reconfiguration of quantum states in -symmetric quasi-one dimensional lattices
We demonstrate mesoscopic transport through quantum states in quasi-1D
lattices maintaining the combination of parity and time-reversal symmetries by
controlling energy gain and loss. We investigate the phase diagram of the
non-Hermitian system where transitions take place between unbroken and broken
-symmetric phases via exceptional points. Quantum transport in
the lattice is measured only in the unbroken phases in the energy band-but not
in the broken phases. The broken phase allows for spontaneous symmetry-broken
states where the cross-stitch lattice is separated into two identical single
lattices corresponding to conditionally degenerate eigenstates. These
degeneracies show a lift-up in the complex energy plane, caused by the
non-Hermiticity with -symmetry.Comment: 12 pages, 7 figure
Antiresonance induced by symmetry-broken contacts in quasi-one-dimensional lattices
We report the effect of symmetry-broken contacts on quantum transport in
quasi-one-dimensional lattices. In contrast to 1D chains, transport in
quasi-one-dimensional lattices, which are made up of a finite number of 1D
chain layers, is strongly influenced by contacts. Contact symmetry depends on
whether the contacts maintain or break the parity symmetry between the layers.
With balanced on-site potential, a flat band can be detected by asymmetric
contacts, but not by symmetric contacts. In the case of asymmetric contacts
with imbalanced on-site potential, transmission is suppressed at certain
energies. We elucidate these energies of transmission suppression related to
antiresonance using reduced lattice models and Feynman paths. These results
provide a nondestructive measurement of flat band energy which it is difficult
to detect.Comment: 8 pages, 5 figure
Flat-band localization and self-collimation of light in photonic crystals
We investigate the optical properties of a photonic crystal composed of a
quasi-one-dimensional flat-band lattice array through finite-difference
time-domain simulations. The photonic bands contain flat bands (FBs) at
specific frequencies, which correspond to compact localized states as a
consequence of destructive interference. The FBs are shown to be nondispersive
along the line, but dispersive along the
line. The FB localization of light in a single direction
only results in a self-collimation of light propagation throughout the photonic
crystal at the FB frequency.Comment: 18 single-column pages, 7 figures including graphical to
JOINT KINEMATICS AND MUSCLE ACTIVITIES TO ACHIEVE SUCCESSFUL BANK-SHOTS IN BASKETBALL FREE-THROW
The study purpose was to investigate joint kinematics and muscle activations and compare clean-shot (CS) and bank-shot (BS) in menβs basketball free-throw. Ten high school male basketball athletes were recruited and asked to perform 10 CS and 10 BS, respectively, in random order. Kinematic results indicated that the range of motions (ROM) of knee, hip, and elbow joints for BS were greater (2.9 to 15.1%) than those of CS. During the projection phase, peak angluar velocities of all joints except the wrist of BS were greater than those of CS. The muscle activity of the triceps brachii increased by about 10.5% across all phases of BS compared to CS. In conclusion, the strategy of successful BS depends on increased joint ROMs and muscle activations of the triceps but similar peak angular velocity of the wrist to CS during the projection phase
Amicus curiae submissions from non governmental organisation
Thesis(Master) --KDI School:Master of Business Administration,2001Outstandingmasterpublishedby Jung-Hee Park
Emergent localized states at the interface of a twofold -symmetric lattice
We consider the role of non-triviality resulting from a non-Hermitian
Hamiltonian that conserves twofold PT-symmetry assembled by interconnections
between a PT-symmetric lattice and its time reversal partner. Twofold
PT-symmetry in the lattice produces additional surface exceptional points that
play the role of new critical points, along with the bulk exceptional point. We
show that there are two distinct regimes possessing symmetry-protected
localized states, of which localization lengths are robust against external
gain and loss. The states are demonstrated by numerical calculation of a
quasi-1D ladder lattice and a 2D bilayered square lattice.Comment: 10 pages, 7 figure
Topological Structure of Dense Hadronic Matter
We present a summary of work done on dense hadronic matter, based on the
Skyrme model, which provides a unified approach to high density, valid in the
large limit. In our picture, dense hadronic matter is described by the
{\em classical} soliton configuration with minimum energy for the given baryon
number density. By incorporating the meson fluctuations on such ground state we
obtain an effective Lagrangian for meson dynamics in a dense medium. Our
starting point has been the Skyrme model defined in terms of pions, thereafter
we have extended and improved the model by incorporating other degrees of
freedom such as dilaton, kaons and vector mesons.Comment: 13 pages, 8 figures, Talk given at the KIAS-APCTP Symposium in
Astro-Hadron Physics "Compact Stars: Quest for New States of Dense Matter",
November 10-14, 2003, Seoul, Korea, published by World Scientific. Based on
talk by B.-Y. Par
Online Class Incremental Learning on Stochastic Blurry Task Boundary via Mask and Visual Prompt Tuning
Continual learning aims to learn a model from a continuous stream of data,
but it mainly assumes a fixed number of data and tasks with clear task
boundaries. However, in real-world scenarios, the number of input data and
tasks is constantly changing in a statistical way, not a static way. Although
recently introduced incremental learning scenarios having blurry task
boundaries somewhat address the above issues, they still do not fully reflect
the statistical properties of real-world situations because of the fixed ratio
of disjoint and blurry samples. In this paper, we propose a new Stochastic
incremental Blurry task boundary scenario, called Si-Blurry, which reflects the
stochastic properties of the real-world. We find that there are two major
challenges in the Si-Blurry scenario: (1) inter- and intra-task forgettings and
(2) class imbalance problem. To alleviate them, we introduce Mask and Visual
Prompt tuning (MVP). In MVP, to address the inter- and intra-task forgetting
issues, we propose a novel instance-wise logit masking and contrastive visual
prompt tuning loss. Both of them help our model discern the classes to be
learned in the current batch. It results in consolidating the previous
knowledge. In addition, to alleviate the class imbalance problem, we introduce
a new gradient similarity-based focal loss and adaptive feature scaling to ease
overfitting to the major classes and underfitting to the minor classes.
Extensive experiments show that our proposed MVP significantly outperforms the
existing state-of-the-art methods in our challenging Si-Blurry scenario
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