1,308 research outputs found
Fragilities of Liquids Predicted from the Random First Order Transition Theory of Glasses
A microscopically motivated theory of glassy dynamics based on an underlying
random first order transition is developed to explain the magnitude of free
energy barriers for glassy relaxation. A variety of empirical correlations
embodied in the concept of liquid "fragility" are shown to be quantitatively
explained by such a model. The near universality of a Lindemann ratio
characterizing the maximal amplitude of thermal vibrations within an amorphous
minimum explains the variation of fragility with a liquid's configurational
heat capacity density. Furthermore the numerical prefactor of this correlation
is well approximated by the microscopic calculation. The size of heterogeneous
reconfiguring regions in a viscous liquid is inferred and the correlation of
nonexponentiality of relaxation with fragility is qualitatively explained. Thus
the wide variety of kinetic behavior in liquids of quite disparate chemical
nature reflects quantitative rather than qualitative differences in their
energy landscapes.Comment: 10 pages including 4 eps figure
An End-to-End Framework For Universal Lesion Detection With Missing Annotations
Fully annotated large-scale medical image datasets are highly valuable.
However, because labeling medical images is tedious and requires specialized
knowledge, the large-scale datasets available often have missing annotation
issues. For instance, DeepLesion, a large-scale CT image dataset with labels
for various kinds of lesions, is reported to have a missing annotation rate of
50\%. Directly training a lesion detector on it would suffer from false
negative supervision caused by unannotated lesions. To address this issue,
previous works have used sophisticated multi-stage strategies to switch between
lesion mining and detector training. In this work, we present a novel
end-to-end framework for mining unlabeled lesions while simultaneously training
the detector. Our framework follows the teacher-student paradigm. In each
iteration, the teacher model infers the input data and creates a set of
predictions. High-confidence predictions are combined with partially-labeled
ground truth for training the student model. On the DeepLesion dataset, using
the original partially labeled training set, our model can outperform all other
more complicated methods and surpass the previous best method by 2.3\% on
average sensitivity and 2.7\% on average precision, achieving state-of-the-art
universal lesion detection results
Bulk Strong Matter: the Trinity
Our world is wonderful because of the normal but negligibly small baryonic
part (i.e., atoms) although unknown dark matter and dark energy dominate the
Universe. A stable atomic nucleus could be simply termed as ``strong matter''
since its nature is dominated by the fundamental strong interaction. Is there
any other form of strong matter? Although nuclei are composed of 2-flavoured
(i.e., up and down flavours of valence quarks) nucleons, it is conjectured that
bulk strong matter could be 3-flavoured (with additional strange quarks) if the
baryon number exceeds the critical value, , in which case quarks
could be either free (so-called strange quark matter) or localized (in
strangeons, coined by combining ``strange nucleon''). Bulk strong matter could
be manifested in the form of compact stars, cosmic rays, and even dark matter.
This trinity will be explained in this brief review, that may impact
dramatically on today's physics, particularly in the era of multi-messenger
astronomy after the discovery of gravitational wave.Comment: 12 pages, 2 figures. Accepted by Advances in Physics:
A Service Restoration Method for Active Distribution Network
AbstractFor a large scale of distributed generations being connected to the power distribution network, the traditional service restoration methods cannot meet the demand of the distributed generation's large access which facing significant challenges. Service restoration of active distribution network (ADN) is a multi-objective, multiple-constraint, and complex optimization problem. Considering the user priority level, the load amounts restored, the counts of switch operation, the network loss after the power restoration, and the operation of power sources, this article establishes a restoration model based on grid actual situation, which is more realistic for the ADN. As a different dimension of different objective, this article proposes the generalized model in order to compare those solutions conveniently, the paper uses genetic algorithm to get recovery scheme. Results of case study show that the proposed model is effective
Granular-ball computing: an efficient, robust, and interpretable adaptive multi-granularity representation and computation method
Human cognition operates on a "Global-first" cognitive mechanism,
prioritizing information processing based on coarse-grained details. This
mechanism inherently possesses an adaptive multi-granularity description
capacity, resulting in computational traits such as efficiency, robustness, and
interpretability. The analysis pattern reliance on the finest granularity and
single-granularity makes most existing computational methods less efficient,
robust, and interpretable, which is an important reason for the current lack of
interpretability in neural networks. Multi-granularity granular-ball computing
employs granular-balls of varying sizes to daptively represent and envelop the
sample space, facilitating learning based on these granular-balls. Given that
the number of coarse-grained "granular-balls" is fewer than sample points,
granular-ball computing proves more efficient. Moreover, the inherent
coarse-grained nature of granular-balls reduces susceptibility to fine-grained
sample disturbances, enhancing robustness. The multi-granularity construct of
granular-balls generates topological structures and coarse-grained
descriptions, naturally augmenting interpretability. Granular-ball computing
has successfully ventured into diverse AI domains, fostering the development of
innovative theoretical methods, including granular-ball classifiers, clustering
techniques, neural networks, rough sets, and evolutionary computing. This has
notably ameliorated the efficiency, noise robustness, and interpretability of
traditional methods. Overall, granular-ball computing is a rare and innovative
theoretical approach in AI that can adaptively and simultaneously enhance
efficiency, robustness, and interpretability. This article delves into the main
application landscapes for granular-ball computing, aiming to equip future
researchers with references and insights to refine and expand this promising
theory
Tackling the Incomplete Annotation Issue in Universal Lesion Detection Task By Exploratory Training
Universal lesion detection has great value for clinical practice as it aims
to detect various types of lesions in multiple organs on medical images. Deep
learning methods have shown promising results, but demanding large volumes of
annotated data for training. However, annotating medical images is costly and
requires specialized knowledge. The diverse forms and contrasts of objects in
medical images make fully annotation even more challenging, resulting in
incomplete annotations. Directly training ULD detectors on such datasets can
yield suboptimal results. Pseudo-label-based methods examine the training data
and mine unlabelled objects for retraining, which have shown to be effective to
tackle this issue. Presently, top-performing methods rely on a dynamic
label-mining mechanism, operating at the mini-batch level. However, the model's
performance varies at different iterations, leading to inconsistencies in the
quality of the mined labels and limits their performance enhancement. Inspired
by the observation that deep models learn concepts with increasing complexity,
we introduce an innovative exploratory training to assess the reliability of
mined lesions over time. Specifically, we introduce a teacher-student detection
model as basis, where the teacher's predictions are combined with incomplete
annotations to train the student. Additionally, we design a prediction bank to
record high-confidence predictions. Each sample is trained several times,
allowing us to get a sequence of records for each sample. If a prediction
consistently appears in the record sequence, it is likely to be a true object,
otherwise it may just a noise. This serves as a crucial criterion for selecting
reliable mined lesions for retraining. Our experimental results substantiate
that the proposed framework surpasses state-of-the-art methods on two medical
image datasets, demonstrating its superior performance
A Survey on UAV-enabled Edge Computing: Resource Management Perspective
Edge computing facilitates low-latency services at the network's edge by
distributing computation, communication, and storage resources within the
geographic proximity of mobile and Internet-of-Things (IoT) devices. The recent
advancement in Unmanned Aerial Vehicles (UAVs) technologies has opened new
opportunities for edge computing in military operations, disaster response, or
remote areas where traditional terrestrial networks are limited or unavailable.
In such environments, UAVs can be deployed as aerial edge servers or relays to
facilitate edge computing services. This form of computing is also known as
UAV-enabled Edge Computing (UEC), which offers several unique benefits such as
mobility, line-of-sight, flexibility, computational capability, and
cost-efficiency. However, the resources on UAVs, edge servers, and IoT devices
are typically very limited in the context of UEC. Efficient resource management
is, therefore, a critical research challenge in UEC. In this article, we
present a survey on the existing research in UEC from the resource management
perspective. We identify a conceptual architecture, different types of
collaborations, wireless communication models, research directions, key
techniques and performance indicators for resource management in UEC. We also
present a taxonomy of resource management in UEC. Finally, we identify and
discuss some open research challenges that can stimulate future research
directions for resource management in UEC.Comment: 36 pages, Accepted to ACM CSU
Heterogeneous firm responses to increases in high-skilled workers: Evidence from China's college enrollment expansion
Over the past several decades, the returns to college education have steadily increased in many countries of the world despite an increased supply of college graduates. In this paper, using local-labor market data on the composition of the labor force combined with detailed firm-level data covering the period of a large-scale expansion of college enrollment in China, we seek to identify within-firm adjustments to labor market changes. The empirical work is guided by a model in which there are two types of production technologies, characterized by two different types of capitals, one skill-biased and the other labor-biased. The empirical results, consistent with the model and the observed trends in schooling and rates of return, indicate that there were significant adjustments in capital and R\&D within-firms in response to an enlarged college-educated labor force
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