161 research outputs found
Simultaneous false discovery proportion bounds via knockoffs and closed testing
We propose new methods to obtain simultaneous false discovery proportion
bounds for knockoff-based approaches. We first investigate an approach based on
Janson and Su's -familywise error rate control method and interpolation. We
then generalize it by considering a collection of values, and show that the
bound of Katsevich and Ramdas is a special case of this method and can be
uniformly improved. Next, we further generalize the method by using closed
testing with a multi-weighted-sum local test statistic. This allows us to
obtain a further uniform improvement and other generalizations over previous
methods. We also develop an efficient shortcut for its implementation. We
compare the performance of our proposed methods in simulations and apply them
to a data set from the UK Biobank
A new iterative algorithm for geolocating a known altitude target using TDOA and FDOA measurements in the presence of satellite location uncertainty
AbstractThis paper considers the problem of geolocating a target on the Earth surface whose altitude is known previously using the target signal time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements obtained at satellites. The number of satellites available for the geolocation task is more than sufficient and their locations are subject to random errors. This paper derives the constrained Cramér-Rao lower bound (CCRLB) of the target position, and on the basis of the CCRLB analysis, an approximately efficient constrained maximum likelihood estimator (CMLE) for geolocating the target is established. A new iterative algorithm for solving the CMLE is then proposed, where the updated target position estimate is shown to be the globally optimal solution to a generalized trust region sub-problem (GTRS) which can be found via a simple bisection search. First-order mean square error (MSE) analysis is conducted to quantify the performance degradation when the known target altitude is assumed to be precise but indeed has an unknown but deterministic error. Computer simulations are used to compare the performance of the proposed iterative geolocation technique with those of two benchmark algorithms. They verify the approximate efficiency of the proposed algorithm and the validity of the MSE analysis
Extended Finite Element Method for Predicting Productivity of Multifractured Horizontal Wells
Based on the theory of the extended finite element method (XFEM), which was first proposed by Moës for dealing with the problem characterized by discontinuities, an extended finite element model for predicting productivity of multifractured horizontal well has been established. The model couples four main porous flow regimes, including fluid flow in the away-from-wellbore region of reservoir matrix, radial flow in the near-wellbore region of reservoir matrix, linear flow in the away-from-wellbore region of fracture, and radial flow in the near-wellbore region of fracture by considering mass transfer between fracture and matrix. The method to introduce the interior well boundary condition into the XFEM is proposed, and therefore the model can be highly adaptable to the complex and asymmetrical physical conditions. Case studies indicate that this kind of multiflow problems can be solved with high accuracy by the use of the XFEM
Effects of Gene Methylation Reprogramming in Cloned Calves Derived from In Vitro-Transfected Somatic Cells
AbstractIn vitro transfection of cultured cells combined with nuclear transfer currently is the most effective procedure to produce transgenic livestock. In the present study, bovine primary fetal fibroblasts were transfected with a green fluorescent protein (GFP) reporter transgene and used as nuclear donor cells in oocyte reconstructions. To examine the role of host cytoplasm on transgene expression and developmental outcome, GFP-expressing fibroblasts were fused to oocytes reconstructed either metaphase or telophase activation, and PCR technology was also employed. The results showed that GFP became detectable at the 8- to 16-cell stage, approximately 80h after reconstruction, and remained positive at all later stages. Embryonic development to the blastocyst stage was not significantly different among metaphase and telophase groups. Therefore, GFP transgene technology can be used to select embryoes derived from transgenic animals
Vicinal Feature Statistics Augmentation for Federated 3D Medical Volume Segmentation
Federated learning (FL) enables multiple client medical institutes
collaboratively train a deep learning (DL) model with privacy protection.
However, the performance of FL can be constrained by the limited availability
of labeled data in small institutes and the heterogeneous (i.e., non-i.i.d.)
data distribution across institutes. Though data augmentation has been a proven
technique to boost the generalization capabilities of conventional centralized
DL as a "free lunch", its application in FL is largely underexplored. Notably,
constrained by costly labeling, 3D medical segmentation generally relies on
data augmentation. In this work, we aim to develop a vicinal feature-level data
augmentation (VFDA) scheme to efficiently alleviate the local feature shift and
facilitate collaborative training for privacy-aware FL segmentation. We take
both the inner- and inter-institute divergence into consideration, without the
need for cross-institute transfer of raw data or their mixup. Specifically, we
exploit the batch-wise feature statistics (e.g., mean and standard deviation)
in each institute to abstractly represent the discrepancy of data, and model
each feature statistic probabilistically via a Gaussian prototype, with the
mean corresponding to the original statistic and the variance quantifying the
augmentation scope. From the vicinal risk minimization perspective, novel
feature statistics can be drawn from the Gaussian distribution to fulfill
augmentation. The variance is explicitly derived by the data bias in each
individual institute and the underlying feature statistics characterized by all
participating institutes. The added-on VFDA consistently yielded marked
improvements over six advanced FL methods on both 3D brain tumor and cardiac
segmentation.Comment: 28th biennial international conference on Information Processing in
Medical Imaging (IPMI 2023): Oral Pape
The Development of LLMs for Embodied Navigation
In recent years, the rapid advancement of Large Language Models (LLMs) such
as the Generative Pre-trained Transformer (GPT) has attracted increasing
attention due to their potential in a variety of practical applications. The
application of LLMs with Embodied Intelligence has emerged as a significant
area of focus. Among the myriad applications of LLMs, navigation tasks are
particularly noteworthy because they demand a deep understanding of the
environment and quick, accurate decision-making. LLMs can augment embodied
intelligence systems with sophisticated environmental perception and
decision-making support, leveraging their robust language and image-processing
capabilities. This article offers an exhaustive summary of the symbiosis
between LLMs and embodied intelligence with a focus on navigation. It reviews
state-of-the-art models, research methodologies, and assesses the advantages
and disadvantages of existing embodied navigation models and datasets. Finally,
the article elucidates the role of LLMs in embodied intelligence, based on
current research, and forecasts future directions in the field. A comprehensive
list of studies in this survey is available at
https://github.com/Rongtao-Xu/Awesome-LLM-E
Estimation and worldwide monitoring of the effective reproductive number of SARS-CoV-2
The effective reproductive number; R; e; is a key indicator of the growth of an epidemic. Since the start of the SARS-CoV-2 pandemic, many methods and online dashboards have sprung up to monitor this number through time. However, these methods are not always thoroughly tested, correctly placed in time, or are overly confident during high incidence periods. Here, we present a method for timely estimation of; R; e; , applied to COVID-19 epidemic data from 170 countries. We thoroughly evaluate the method on simulated data, and present an intuitive web interface for interactive data exploration. We show that, in early 2020, in the majority of countries the estimated; R; e; dropped below 1 only after the introduction of major non-pharmaceutical interventions. For Europe the implementation of non-pharmaceutical interventions was broadly associated with reductions in the estimated; R; e; . Globally though, relaxing non-pharmaceutical interventions had more varied effects on subsequent; R; e; estimates. Our framework is useful to inform governments and the general public on the status of epidemics in their country, and is used as the official source of; R; e; estimates for SARS-CoV-2 in Switzerland. It further allows detailed comparison between countries and in relation to covariates such as implemented public health policies, mobility, behaviour, or weather data
The cosmic ray test of MRPCs for the BESIII ETOF upgrade
In order to improve the particle identification capability of the Beijing
Spectrometer III (BESIII),t is proposed to upgrade the current endcap
time-of-flight (ETOF) detector with multi-gap resistive plate chamber (MRPC)
technology. Aiming at extending ETOF overall time resolution better than 100ps,
the whole system including MRPC detectors, new-designed Front End Electronics
(FEE), CLOCK module, fast control boards and time to digital modules (TDIG),
was built up and operated online 3 months under the cosmic ray. The main
purposes of cosmic ray test are checking the detectors' construction quality,
testing the joint operation of all instruments and guaranteeing the performance
of the system. The results imply MRPC time resolution better than 100,
efficiency is about 98 and the noise rate of strip is lower than
1() at normal threshold range, the details are discussed and
analyzed specifically in this paper. The test indicates that the whole ETOF
system would work well and satisfy the requirements of upgrade
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