151 research outputs found
Extension and parameterization of high-order density dependence in Skyrme forces
The three-body force is indispensable in nuclear energy density functionals
which leads to a density dependent two-body term in the Hartree-Fock approach.
Usually a single factional power of density dependency has been adopted. We
consider the possibility of an additional higher-order density dependence in
extended Skyrme forces. As a result, new extended Skyrme parametertizations
based on the SLy4 force are obtained and the improvements in descriptions of
global nuclei have been demonstrated. The higher-order term can also
substantially affect nuclear properties in the high density region in general
ways.Comment: 6 pages, 5 figure
Non-Wilson-Fisher kinks of numerical bootstrap: from the deconfined phase transition to a putative new family of CFTs
It is well established that the Wilson-Fisher (WF) CFT sits at a kink
of the numerical bounds from bootstrapping four point function of
vector. Moving away from the WF kinks, there indeed exists another family of
kinks (dubbed non-WF kinks) on the curve of numerical bounds. Different
from the WF kinks that exist for arbitary in dimensions, the
non-WF kinks exist in arbitrary dimensions but only for a large enough
in a given dimension . In this paper we have achieved a thorough
understanding for few special cases of these non-WF kinks. The first case is
the bootstrap in 2d, where the non-WF kink turns out to be the
Wess-Zumino-Witten (WZW) model, and all the WZW models saturate
the numerical bound on the left side of the kink. We further carry out
dimensional continuation of the 2d kink towards the 3d
deconfined phase transition. We find the kink disappears at around
dimensions indicating the deconfined phase transition is weakly first
order. The second interesting observation is, the bootstrap bound does
not show any kink in 2d (), but is surprisingly saturated by the 2d free
boson CFT (also called Luttinger liquid) all the way on the numerical curve.
The last case is the limit, where the non-WF kink sits at
in dimensions. We manage to write down
its analytical four point function in arbitrary dimensions, which equals to the
subtraction of correlation functions of a free fermion theory and generalized
free theory. An important feature of this solution is the existence of a full
tower of conserved higher spin current. We speculate that a new family of CFTs
will emerge at non-WF kinks for finite , in a similar fashion as WF
CFTs originating from free boson at .Comment: 14+2 pages; v2 typo correcte
A roadmap for bootstrapping gauge theories: decoupling operators of conformal field theories in dimensions
We propose a roadmap for bootstrapping conformal field theories (CFTs)
described by gauge theories in dimensions . In particular, we provide a
simple and workable answer to the question of how to detect the gauge group in
the bootstrap calculation. Our recipe is based on the notion of decoupling
operator, which has a simple (gauge) group theoretical origin, and is
reminiscent of the null operator of Wess-Zumino-Witten CFTs in higher
dimensions. Using the decoupling operator we can efficiently detect the rank
(i.e. color number) of gauge groups, e.g., by imposing gap conditions in the
CFT spectrum. We also discuss the physics of the equation of motion, which has
interesting consequences in the CFT spectrum as well. As an application of our
recipes, we study a prototypical gauge theory, namely the scalar QED which has
a gauge field interacting with critical bosons. In
dimensions we successfully solve it by obtaining a kink as well as an island of
the scalar QED. Further attempt towards the scalar QED is also discussed.Comment: 31 pages plus references, 8 figure
Charlton Fire Department Resident Expectations: Survey and Analysis
The Town of Charlton is located in the heart of the Massachusetts with a resident population of just under 14,000 people. The Charlton Fire Department serves the town for needs related to fire fighting, fire prevention, burning permits and inspection services along with emergency medical services. The Department has requested the assistance of the Clark University COPACE Capstone students in creating and conducting survey in order to get a sense of what the resident of the town know about the fire department and to better gauge their expectations about what the department can provide for them. The survey was formulated in conjunction with the Fire Department and was conducted for a two-week period in April 2016. This report seeks to summarize and analyze the survey formulation process, the results of the survey and recommend best practices for the Charlton Fire Department in their resident engagement efforts in the future
Speed of Sound and Phase Transitions in Neutron Stars Indicated by the Thick Neutron Skin of Pb
The speed of sound is a novel probe of equation of state and phase
transitions in dense cores of neutron stars. Recently nuclear experiments
extracted a surprising thick neutron skin of Pb, causing tensions to
reproduce the tidal deformability in gravitational-wave observations. This work
finds that exotic structures in the speed of sound with a small softening slope
followed by a steep-rising peak are required to reconcile the thick neutron
skin of Pb with astronomical observations of neutron stars.
Furthermore, the peak of speed of sound is narrowly constrained around two
times the nuclear saturation density with the thick neutron skin. Consequently
early and strong first-order phase transitions are comparatively more
favorable.Comment: 5 pages 4 figures, submitte
NeRRF: 3D Reconstruction and View Synthesis for Transparent and Specular Objects with Neural Refractive-Reflective Fields
Neural radiance fields (NeRF) have revolutionized the field of image-based
view synthesis. However, NeRF uses straight rays and fails to deal with
complicated light path changes caused by refraction and reflection. This
prevents NeRF from successfully synthesizing transparent or specular objects,
which are ubiquitous in real-world robotics and A/VR applications. In this
paper, we introduce the refractive-reflective field. Taking the object
silhouette as input, we first utilize marching tetrahedra with a progressive
encoding to reconstruct the geometry of non-Lambertian objects and then model
refraction and reflection effects of the object in a unified framework using
Fresnel terms. Meanwhile, to achieve efficient and effective anti-aliasing, we
propose a virtual cone supersampling technique. We benchmark our method on
different shapes, backgrounds and Fresnel terms on both real-world and
synthetic datasets. We also qualitatively and quantitatively benchmark the
rendering results of various editing applications, including material editing,
object replacement/insertion, and environment illumination estimation. Codes
and data are publicly available at https://github.com/dawning77/NeRRF
CoIN: A Benchmark of Continual Instruction tuNing for Multimodel Large Language Model
Instruction tuning represents a prevalent strategy employed by Multimodal
Large Language Models (MLLMs) to align with human instructions and adapt to new
tasks. Nevertheless, MLLMs encounter the challenge of adapting to users'
evolving knowledge and demands. Therefore, how to retain existing skills while
acquiring new knowledge needs to be investigated. In this paper, we present a
comprehensive benchmark, namely Continual Instruction tuNing (CoIN), to assess
existing MLLMs in the sequential instruction tuning paradigm. CoIN comprises 10
commonly used datasets spanning 8 task categories, ensuring a diverse range of
instructions and tasks. Besides, the trained model is evaluated from two
aspects: Instruction Following and General Knowledge, which assess the
alignment with human intention and knowledge preserved for reasoning,
respectively. Experiments on CoIN demonstrate that current powerful MLLMs still
suffer catastrophic forgetting, and the failure in intention alignment assumes
the main responsibility, instead of the knowledge forgetting. To this end, we
introduce MoELoRA to MLLMs which is effective to retain the previous
instruction alignment. Experimental results consistently illustrate the
forgetting decreased from this method on CoIN
CUCL: Codebook for Unsupervised Continual Learning
The focus of this study is on Unsupervised Continual Learning (UCL), as it
presents an alternative to Supervised Continual Learning which needs
high-quality manual labeled data. The experiments under the UCL paradigm
indicate a phenomenon where the results on the first few tasks are suboptimal.
This phenomenon can render the model inappropriate for practical applications.
To address this issue, after analyzing the phenomenon and identifying the lack
of diversity as a vital factor, we propose a method named Codebook for
Unsupervised Continual Learning (CUCL) which promotes the model to learn
discriminative features to complete the class boundary. Specifically, we first
introduce a Product Quantization to inject diversity into the representation
and apply a cross quantized contrastive loss between the original
representation and the quantized one to capture discriminative information.
Then, based on the quantizer, we propose an effective Codebook Rehearsal to
address catastrophic forgetting. This study involves conducting extensive
experiments on CIFAR100, TinyImageNet, and MiniImageNet benchmark datasets. Our
method significantly boosts the performances of supervised and unsupervised
methods. For instance, on TinyImageNet, our method led to a relative
improvement of 12.76% and 7% when compared with Simsiam and BYOL, respectively.Comment: MM '23: Proceedings of the 31st ACM International Conference on
Multimedi
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The Effects of Excess Co on the Phase Composition and Thermoelectric Properties of Half-Heusler NbCoSb
NbCoSb with nominal 19 valence electrons, and is supposed to be metallic, has recently been reported to also exhibit the thermoelectric properties of a heavily doped n-type semiconductor. In this study, we prepared Co-rich NbCo1+xSb samples (x = 0, 0.2, 0.3, 0.4, 0.5), and their phase compositions, microstructures and thermoelectric properties were investigated. The Seebeck coefficient increased a great deal with increasing x, due to decreasing carrier concentration, and the total thermal conductivity reduced mainly because of declining κe. Finally, a peak thermoelectric figure of merit, ZT, was about 0.46 for NbCo1.3Sb at 973 K. This enhancement was mainly attributed to the reduction of electric thermal conductivity and the increase of Seebeck coefficient. The excess Co had effects on the carrier concentration, deformation potential Edef and DOS effective mass m*. Adding an excessive amount of Co leads to a very high Edef, which was detrimental for transport characteristics
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