1,229 research outputs found
Charge Transfer Fluctuations as a QGP Signal
In this study, we analyze the recently proposed charge transfer fluctuations
within a finite pseudo-rapidity space. As the charge transfer fluctuation is a
measure of the local charge correlation length, it is capable of detecting
inhomogeneity in the hot and dense matter created by heavy ion collisions. We
predict that going from peripheral to central collisions, the charge transfer
fluctuations at midrapidity should decrease substantially while the charge
transfer fluctuations at the edges of the observation window should decrease by
a small amount. These are consequences of having a strongly inhomogeneous
matter where the QGP component is concentrated around midrapidity. We also show
how to constrain the values of the charge correlations lengths in both the
hadronic phase and the QGP phase using the charge transfer fluctuations.
Current manuscript is based on the preprints hep-ph/0503085 (to appear in
Physical Review C) and nucl-th/0506025.Comment: To appear in the proceedings of 18th International Conference on
Ultrarelativistic Nucleus-Nucleus Collisions: Quark Matter 2005 (QM 2005),
Budapest, Hungary, 4-9 Aug 200
Quantum critical properties of the Bose-Fermi Kondo Model in a large-N limit
Studies of non-Fermi liquid properties in heavy fermions have led to the
current interest in the Bose-Fermi Kondo model. Here we use a dynamical large-N
approach to analyze an SU(N)xSU() generalization of the model. We
establish the existence in this limit of an unstable fixed point when the
bosonic bath has a sub-ohmic spectrum (|\omega|^{1-\epsilon} \sgn \omega,
with ). At the quantum critical point, the Kondo scale vanishes
and the local spin susceptibility (which is finite on the Kondo side for \kappa
<1) diverges. We also find an \omega/T scaling for an extended range (15
decades) of \omega/T. This scaling violates (for ) the
expectation of a naive mapping to certain classical models in an extra
dimension; it reflects the inherent quantum nature of the critical point.Comment: 4 pages; v2: included clarifying discussions on why the omega/T
scaling (for epsilon >=1/2) violates the naive mapping to classical models in
an extra dimension and the implications of this observation about the nature
of the QCP; v3: shortened to conform to the PRL length limi
Monotone Cubic B-Splines
We present a method for fitting monotone curves using cubic B-splines with a
monotonicity constraint on the coefficients. We explore different ways of
enforcing this constraint and analyze their theoretical and empirical
properties. We propose two algorithms for solving the spline fitting problem:
one that uses standard optimization techniques and one that trains a
Multi-Layer Perceptrons (MLP) generator to approximate the solutions under
various settings and perturbations. The generator approach can speed up the
fitting process when we need to solve the problem repeatedly, such as when
constructing confidence bands using bootstrap. We evaluate our method against
several existing methods, some of which do not use the monotonicity constraint,
on some monotone curves with varying noise levels. We demonstrate that our
method outperforms the other methods, especially in high-noise scenarios. We
also apply our method to analyze the polarization-hole phenomenon during star
formation in astrophysics. The source code is accessible at
\texttt{\url{https://github.com/szcf-weiya/MonotoneSplines.jl}}
Visualization of lithium-ion transport and phase evolution within and between manganese oxide nanorods.
Multiple lithium-ion transport pathways and local phase changes upon lithiation in silver hollandite are revealed via in situ microscopy including electron diffraction, imaging and spectroscopy, coupled with density functional theory and phase field calculations. We report unexpected inter-nanorod lithium-ion transport, where the reaction fronts and kinetics are maintained within the neighbouring nanorod. Notably, this is the first time-resolved visualization of lithium-ion transport within and between individual nanorods, where the impact of oxygen deficiencies is delineated. Initially, fast lithium-ion transport is observed along the long axis with small net volume change, resulting in two lithiated silver hollandite phases distinguishable by orthorhombic distortion. Subsequently, a slower reaction front is observed, with formation of polyphase lithiated silver hollandite and face-centred-cubic silver metal with substantial volume expansion. These results indicate lithium-ion transport is not confined within a single nanorod and may provide a paradigm shift for one-dimensional tunnelled materials, particularly towards achieving high-rate capability
Investigation of nonlinear flame response to dual-frequency disturbances
The two-way interaction between the unsteady flame heat release rate and
acoustic waves can lead to combustion instability within combustors. To
understand and quantify the flame response to oncoming acoustic waves, previous
studies have typically considered the flame dynamic response to pure tone
forcing and assumed a dynamically linear or weakly nonlinear response. In this
study, the introduction of excitation with two distinct frequencies denoted
and is considered, including the effect of excitation amplitude
in order to gain more insight into the nature of flame nonlinearities and these
associated with combustion instabilities. Corresponding results are obtained by
combining a low-order asymptotic analysis (up to third order in normalised
excitation amplitude) with numerical methods based on the model framework of
the -equation. The influence paths of the disturbance at on the flame
dynamic response at are studied in detail. Due to the flame propagating
forward normally to itself (named flame kinematic restoration), the
perturbation at acts together with that at to induce a
third-order nonlinear interaction in the flame kinematics, impressively
suppressing the spatial wrinkling of the flame at . Additionally,
introducing the perturbation at alters the effective flame displacement
speed, which is responsible for the calculation of the flame heat release rate
and further affects the global response at . Taking into account the
above two factors, the nonlinear response of the flame at is completely
quantified and the corresponding characteristics are clearly interpreted
Cooperative Multi-agent Bandits: Distributed Algorithms with Optimal Individual Regret and Constant Communication Costs
Recently, there has been extensive study of cooperative multi-agent
multi-armed bandits where a set of distributed agents cooperatively play the
same multi-armed bandit game. The goal is to develop bandit algorithms with the
optimal group and individual regrets and low communication between agents. The
prior work tackled this problem using two paradigms: leader-follower and fully
distributed algorithms. Prior algorithms in both paradigms achieve the optimal
group regret. The leader-follower algorithms achieve constant communication
costs but fail to achieve optimal individual regrets. The state-of-the-art
fully distributed algorithms achieve optimal individual regrets but fail to
achieve constant communication costs. This paper presents a simple yet
effective communication policy and integrates it into a learning algorithm for
cooperative bandits. Our algorithm achieves the best of both paradigms: optimal
individual regret and constant communication costs
Par-4: An Attractive Target for Cancer Therapy
Lack of early diagnosis, cancer recurrence, metastasis, and adverse side effects are some of the major problems in the treatment of cancers. Par-4, a tumor suppressor protein, is an attractive target for cancer therapy as it selectively kills cancer cells. Cl-Par-4 is the active fragment of Par-4 that enters the nucleus and selectively induces apoptosis in cancer cells. It has also been reported that Par-4 increases the susceptibility of cancer cells to chemotherapy and reverses cancer recurrence. Further, Par-4 has been shown to play a dual role: inhibition of EMT (Epithelial-mesenchymal transition) as well as assistance in the reverse process, thereby lowering the chance of cancer metastasis. Because of these unique properties of Par-4, it offers an attractive target for developing anticancer therapy. However, so far only the C-terminal coiled-coil domain has been studied structurally. Here, we have optimized conditions that will be helpful in the structural determination of cl-Par-4 using NMR and X-ray crystallography.https://digitalcommons.odu.edu/gradposters2023_sciences/1017/thumbnail.jp
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Diabetic plantar pressure analysis using image fusion
Plantar pressure images analysis is the key issue of designing comfortable shoe products through last customizing system, which has attracted the researchers’ curiosity toward image fusion as an application of medical and industrial imaging. In the current work, image fusion has been applied using wavelet transform and compared with Laplace Pyramid. Using image fusion rules of Mean-Max, we presented a plantar pressure image fusion method employing haar wavelet transform. It was compared in different composition layers with the Laplace pyramid transform. The experimental studies deployed the haar, db2, sym4, coif2, and bior5.5 wavelet basis functions for image fusion under decomposition layers of 3, 4, and 5. Evaluation metrics were measured in the case of the different layer number of wavelet decomposition to determine the best decomposition level and to evaluate the fused image quality using with different wavelet functions. The best wavelet basis function and decomposition layers were selected through the analysis and the evaluation measurements. This study established that haar wavelet transform with five decomposition levels on plantar pressure image achieved superior performance of 89.2817% mean, 89.4913% standard deviation, 5.4196 average gradient, 14.3364 spatial frequency, 5.9323 information entropy and 0.2206 cross entropy
Two-dimensional correlation spectroscopy of two-exciton resonances in semiconductor quantum wells
We propose a three-pulse coherent ultrafast optical technique that is
particularly sensitive to two-exciton correlations. Two Liouville-space
pathways for the density matrix contribute to this signal which reveals double
quantum coherences when displayed as a two-dimensional correlation plot.
Two-exciton couplings spread the cross peaks along both axes, creating a
characteristic highly resolved pattern. This level of detail is not available
from conventional one-dimensional four-wave mixing or other two-dimensional
correlation spectroscopy signals such as the photo echo, in which two-exciton
couplings show up along a single axis and are highly congested
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