11,635 research outputs found
Measurement of flow volume in the presence of reverse flow with ultrasound speckle decorrelation
Direct measurement of volumetric flow rate in the cardiovascular system with ultrasound is valuable but has been a challenge because most current 2-D flow imaging techniques are only able to estimate the flow velocity in the scanning plane (in-plane). Our recent study demonstrated that high frame rate contrast ultrasound and speckle decorrelation (SDC) can be used to accurately measure the speed of flow going through the scanning plane (through-plane). The volumetric flow could then be calculated by integrating over the luminal area, when the blood vessel was scanned from the transverse view. However, a key disadvantage of this SDC method is that it cannot distinguish the direction of the through-plane flow, which limited its applications to blood vessels with unidirectional flow. Physiologic flow in the cardiovascular system could be bidirectional due to its pulsatility, geometric features, or under pathologic situations. In this study, we proposed a method to distinguish the through-plane flow direction by inspecting the flow within the scanning plane from a tilted transverse view. This method was tested on computer simulations and experimental flow phantoms. It was found that the proposed method could detect flow direction and improved the estimation of the flow volume, reducing the overestimation from over 100% to less than 15% when there was flow reversal. This method showed significant improvement over the current SDC method in volume flow estimation and can be applied to a wider range of clinical applications where bidirectional flow exists
On low-sampling-rate Kramers-Moyal coefficients
We analyze the impact of the sampling interval on the estimation of
Kramers-Moyal coefficients. We obtain the finite-time expressions of these
coefficients for several standard processes. We also analyze extreme situations
such as the independence and no-fluctuation limits that constitute useful
references. Our results aim at aiding the proper extraction of information in
data-driven analysis.Comment: 9 pages, 4 figure
Effects of polarization and permittivity gradients and other parameters on the anomalous vertical shift behavior of graded ferroelectric thin films
Author name used in this publication: Y. ZhouAuthor name used in this publication: C. H. LamAuthor name used in this publication: F. G. Shin2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Shear Bond Strength and Remineralisation Effect of a Casein Phosphopeptide-Amorphous Calcium Phosphate-Modified Glass Ionomer Cement on Artificial “Caries-Affected” Dentine
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Mechanisms of imprint effect on ferroelectric thin films
Author name used in this publication: Y. ZhouAuthor name used in this publication: C. H. LamAuthor name used in this publication: F. G. Shin2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Ultrasonic extraction of flavonoids and phenolics from loquat (Eriobotrya japonica Lindl.) flowers
Ethanol was used to extract flavonoids and phenolics from loquat (Eriobotrya japonica Lindl. cv. Ruantiaobaisha) flowers with ultrasonic pharmaceutical managing machine. Single-factor and orthogonal experiment were used to investigate the optimum extraction condition. The results showed that, the combination of 30°C, 80 min, 60% ethanol and 1:40 material ratio was optimum extraction condition with the highest yields of flavonoids and phenolics at 47 kHz/500 W. Under the optimum extraction condition, two consecutive extractions was enough, the extraction rates of flavonoids and phenolics were all more than 90%, with the contents of 10.59 and 102.02 mg/g dry weight, respectively.Key words: Eriobotrya japonica, flower, flavonoids, phenolics, ultrasonic extraction
Sociocultural Norm Similarities and Differences via Situational Alignment and Explainable Textual Entailment
Designing systems that can reason across cultures requires that they are
grounded in the norms of the contexts in which they operate. However, current
research on developing computational models of social norms has primarily
focused on American society. Here, we propose a novel approach to discover and
compare descriptive social norms across Chinese and American cultures. We
demonstrate our approach by leveraging discussions on a Chinese Q&A platform
(Zhihu) and the existing SocialChemistry dataset as proxies for contrasting
cultural axes, align social situations cross-culturally, and extract social
norms from texts using in-context learning. Embedding Chain-of-Thought
prompting in a human-AI collaborative framework, we build a high-quality
dataset of 3,069 social norms aligned with social situations across Chinese and
American cultures alongside corresponding free-text explanations. To test the
ability of models to reason about social norms across cultures, we introduce
the task of explainable social norm entailment, showing that existing models
under 3B parameters have significant room for improvement in both automatic and
human evaluation. Further analysis of cross-cultural norm differences based on
our dataset shows empirical alignment with the social orientations framework,
revealing several situational and descriptive nuances in norms across these
cultures.Comment: EMNLP 2023 Main Conference (Long Paper
Understanding the Epidemiology of Heart Failure to Improve Management Practices: An Asia-Pacific Perspective
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Quantum Computing with Very Noisy Devices
In theory, quantum computers can efficiently simulate quantum physics, factor
large numbers and estimate integrals, thus solving otherwise intractable
computational problems. In practice, quantum computers must operate with noisy
devices called ``gates'' that tend to destroy the fragile quantum states needed
for computation. The goal of fault-tolerant quantum computing is to compute
accurately even when gates have a high probability of error each time they are
used. Here we give evidence that accurate quantum computing is possible with
error probabilities above 3% per gate, which is significantly higher than what
was previously thought possible. However, the resources required for computing
at such high error probabilities are excessive. Fortunately, they decrease
rapidly with decreasing error probabilities. If we had quantum resources
comparable to the considerable resources available in today's digital
computers, we could implement non-trivial quantum computations at error
probabilities as high as 1% per gate.Comment: 47 page
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