90 research outputs found
Twotier -- A Layered Analysis of Backbone Members in a Moderate Sized Community Sports Organization
Backbone members are recognized as essential parts of an organization, yet
their role and mechanisms of functioning in networks are not fully understood.
In this paper, we propose a new framework called Twotier to analyze the
evolution of community sports organizations (CSOs) and the role of backbone
members. Tier-one establishes a dynamic user interaction network based on
grouping relationships, and weighted k-shell decomposition is used to select
backbone members. We perform community detection and capture the evolution of
two separate sub-networks: one formed by backbone members and the other formed
by other members. In Tier-two, the sub-networks are abstracted, revealing a
core-periphery structure in the organization where backbone members serve as
bridges connecting all parts of the network. Our findings suggest that relying
on backbone members can keep newcomers actively involved in rewarding
activities, while non-rewarding activities solidify relations between backbone
members
Cognitive Mirage: A Review of Hallucinations in Large Language Models
As large language models continue to develop in the field of AI, text
generation systems are susceptible to a worrisome phenomenon known as
hallucination. In this study, we summarize recent compelling insights into
hallucinations in LLMs. We present a novel taxonomy of hallucinations from
various text generation tasks, thus provide theoretical insights, detection
methods and improvement approaches. Based on this, future research directions
are proposed. Our contribution are threefold: (1) We provide a detailed and
complete taxonomy for hallucinations appearing in text generation tasks; (2) We
provide theoretical analyses of hallucinations in LLMs and provide existing
detection and improvement methods; (3) We propose several research directions
that can be developed in the future. As hallucinations garner significant
attention from the community, we will maintain updates on relevant research
progress.Comment: work in progress; 21 page
Understanding the power-law nature of participation in community sports organizations
The improvement of living standards and awareness of chronic diseases have
increased the importance of community sports organizations in promoting the
physical activity levels of the public. However, limited understanding of human
behavior in this context often leads to suboptimal resource utilization. In
this study, we analyzed the participation behavior of 2,956 members with a time
span of 6 years in a community sports organization. Our study reveals that, at
the population level, the participation frequency in activities adheres to a
power-law distribution. To understand the underlying mechanisms driving crowd
participation, we introduce a novel behavioral model called HFBI
(Habit-Formation and Behavioral Inertia), demonstrating a robust fit to the
observed power-law distribution. The habit formation mechanism indicates that
individuals who are more engaged are more likely to maintain participation,
while the behavioral inertia mechanism suggests that individuals' willingness
to participate in activities diminishes with their absences from activities. At
the individual level, our analysis reveals a burst-quiet participation pattern,
with bursts often commencing with incentive activities. We also find a
power-law distribution in the intervals between individual participations. Our
research offers valuable insights into the complex dynamics of human
participation in community sports activity and provides a theoretical
foundation to inform intervention design. Furthermore, the flexibility of our
model enables its application to other data exhibiting power-law properties,
broadening its potential impact beyond the realm of community sports
Dipolar Dynamics for Interacting Ultracold Fermions in a Trapped Optical Lattice
Using the time-dependent density matrix renormalization group method, we
calculate transport properties of an interacting Fermi gas in an optical
lattice with a confining trap after a sudden displacement of the trap center.
In the regime of attractive interactions, the dipolar motion after the
displacement can be classified into underdamped oscillations and overdamped
relaxations, depending on the interaction strength. These numerical
calculations are consistent with experimental results. In the regime of
repulsive interactions, we predict a revival of the oscillations of the center
of mass when the interaction strength is increased. This unique feature can be
considered as a dynamical signature for the emergence of a Mott plateau for an
interacting trapped Fermi gas in an optical lattice.Comment: 5 pages, 5 figure
Trapped Ultracold Bosons in Periodically Modulated Lattices
Motivated by the recent rapid development of the field of quantum gases in
optical lattices, we present a comprehensive study of the spectrum of ultracold
atoms in a one-dimensional optical lattice subjected to a periodic lattice
modulation. Using the time-dependent density-matrix renormalization group
method, we study the dynamical response due to lattice modulations in different
quantum phases of the system with varying density. For the Mott insulating
state, we identify several excitation processes, which provide important
information about the density profile of the gases. For the superfluid, the
dynamical response can be well described in a local density approximation. This
simplification can be valuable in understanding the strong-correlated
superfluid in a slow-varying harmonic potential. All these spectroscopic
features of an inhomogeneous system can be used as a test for the validity of
the Bose-Hubbard model in a parabolic trapping potential.Comment: 8 pages, 6 figure
Population-Based Evolutionary Gaming for Unsupervised Person Re-identification
Unsupervised person re-identification has achieved great success through the
self-improvement of individual neural networks. However, limited by the lack of
diversity of discriminant information, a single network has difficulty learning
sufficient discrimination ability by itself under unsupervised conditions. To
address this limit, we develop a population-based evolutionary gaming (PEG)
framework in which a population of diverse neural networks is trained
concurrently through selection, reproduction, mutation, and population mutual
learning iteratively. Specifically, the selection of networks to preserve is
modeled as a cooperative game and solved by the best-response dynamics, then
the reproduction and mutation are implemented by cloning and fluctuating
hyper-parameters of networks to learn more diversity, and population mutual
learning improves the discrimination of networks by knowledge distillation from
each other within the population. In addition, we propose a cross-reference
scatter (CRS) to approximately evaluate re-ID models without labeled samples
and adopt it as the criterion of network selection in PEG. CRS measures a
model's performance by indirectly estimating the accuracy of its predicted
pseudo-labels according to the cohesion and separation of the feature space.
Extensive experiments demonstrate that (1) CRS approximately measures the
performance of models without labeled samples; (2) and PEG produces new
state-of-the-art accuracy for person re-identification, indicating the great
potential of population-based network cooperative training for unsupervised
learning.Comment: Accepted in IJC
Local spin fluctuations in iron-based superconductors: 77Se and 87Rb NMR measurements of Tl0.47Rb0.34Fe1.63Se2
We report nuclear magnetic resonance (NMR) studies of the intercalated iron
selenide superconductor (Tl, Rb)FeSe ( K).
Single-crystal measurements up to 480 K on both Se and Rb nuclei
show a superconducting phase with no magnetic order. The Knight shifts and
relaxation rates increase very strongly with temperature above ,
before flattening at 400 K. The quadratic -dependence and perfect
proportionality of both and data demonstrate their origin in
paramagnetic moments. A minimal model for this pseudogap-like response is not a
missing density of states but two additive contributions from the itinerant
electronic and local magnetic components, a framework unifying the and
data in many iron-based superconductors
Elevated diversity of the supply chain boosts global food system resilience
Food supply shock is defined as a drastic shortage in food supply, which would likely threaten the achievement of Sustainable Development Goals 2: zero hunger. Traditionally, highly-connected global food supply system was deemed to help overcome shortages easily in response to food supply shock. However, recent studies suggested that overconnected trade networks potentially increase exposure to external shocks and amplify shocks. Here, we develop an empirical–statistical method to quantitatively and meticulously measure the diversity of international food supply chain. Our results show that boosting a country’s food supply chain diversity will increase the resistance of the country to food shocks. The global diversity of food supply chain increased gradually during 1986–2021; correspondingly, the intensity of food shocks decreased, the recovery speed after a shock increased. The food supply chain diversity in high-income countries is significantly higher than that in other countries, although it has improved greatly in the least developed regions, like Africa and Middle East. International emergencies and geopolitical events like the Russia–Ukraine conflict could potentially threaten global food security and impact low-income countries the most. Our study provides a reference for measuring resilience of national food system, thus helping managers or policymakers mitigate the risk of food supply shocks
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