88 research outputs found
Fast Conditional Mixing of MCMC Algorithms for Non-log-concave Distributions
MCMC algorithms offer empirically efficient tools for sampling from a target
distribution . However, on the theory side, MCMC
algorithms suffer from slow mixing rate when is non-log-concave. Our
work examines this gap and shows that when Poincar\'e-style inequality holds on
a subset of the state space, the conditional distribution of MCMC
iterates over mixes fast to the true conditional distribution.
This fast mixing guarantee can hold in cases when global mixing is provably
slow. We formalize the statement and quantify the conditional mixing rate. We
further show that conditional mixing can have interesting implications for
sampling from mixtures of Gaussians, parameter estimation for Gaussian mixture
models and Gibbs-sampling with well-connected local minima.Comment: Camera ready versio
Media Bias Matters: Understanding the Impact of Politically Biased News on Vaccine Attitudes in Social Media
News media has been utilized as a political tool to stray from facts,
presenting biased claims without evidence. Amid the COVID-19 pandemic,
politically biased news (PBN) has significantly undermined public trust in
vaccines, despite strong medical evidence supporting their efficacy. In this
paper, we analyze: (i) how inherent vaccine stances subtly influence
individuals' selection of news sources and participation in social media
discussions; and (ii) the impact of exposure to PBN on users' attitudes toward
vaccines. In doing so, we first curate a comprehensive dataset that connects
PBN with related social media discourse. Utilizing advanced deep learning and
causal inference techniques, we reveal distinct user behaviors between social
media groups with various vaccine stances. Moreover, we observe that
individuals with moderate stances, particularly the vaccine-hesitant majority,
are more vulnerable to the influence of PBN compared to those with extreme
views. Our findings provide critical insights to foster this line of research.Comment: 9 pages, 6 figures, 3 table
A Comparative Analysis of U-Net and Vision Transformer Architectures in Semi-Supervised Prostate Zonal Segmentation
The precise segmentation of different regions of the prostate is crucial in the diagnosis and treatment of prostate-related diseases. However, the scarcity of labeled prostate data poses a challenge for the accurate segmentation of its different regions. We perform the segmentation of different regions of the prostate using U-Net- and Vision Transformer (ViT)-based architectures. We use five semi-supervised learning methods, including entropy minimization, cross pseudo-supervision, mean teacher, uncertainty-aware mean teacher (UAMT), and interpolation consistency training (ICT) to compare the results with the state-of-the-art prostate semi-supervised segmentation network uncertainty-aware temporal self-learning (UATS). The UAMT method improves the prostate segmentation accuracy and provides stable prostate region segmentation results. ICT plays a more stable role in the prostate region segmentation results, which provides strong support for the medical image segmentation task, and demonstrates the robustness of U-Net for medical image segmentation. UATS is still more applicable to the U-Net backbone and has a very significant effect on a positive prediction rate. However, the performance of ViT in combination with semi-supervision still requires further optimization. This comparative analysis applies various semi-supervised learning methods to prostate zonal segmentation. It guides future prostate segmentation developments and offers insights into utilizing limited labeled data in medical imaging
A Novel Regulator of Preadipocyte Differentiation, Transcription Factor TCF21, Functions Partially Through Promoting LPL Expression
The transcription factor TCF21 has been previously shown to be specifically expressed in white preadipocytes in mice. However, the exact biological function of TCF21 in the context of adipogenesis remains unknown. In the current study, we used chicken lines selected based on their abdominal fat content, and observed a significant decrease in TCF21 mRNA and protein levels in the abdominal fat of lean broilers relative to fat broilers. Moreover, TCF21 expression increased throughout preadipocyte differentiation in vitro. We also found that TCF21 knockdown and over-expression attenuated and promoted preadipocyte differentiation, respectively, as evidenced by appropriate changes in lipid droplet accumulation and altered expressions of C/EBPa, LPL, and A-FABP. Additional chromatin immunoprecipitation analyses and luciferase assays demonstrated that TCF21 promotes the transcription of LPL by directly binding to the E-box motif in the LPL promoter. Together, these results show that TCF21 is a novel regulator of preadipocyte differentiation, in part by directly promoting LPL expression
Validation of Human Telomere Length Multi-Ancestry Meta-Analysis Association Signals Identifies POP5 and KBTBD6 as Human Telomere Length Regulation Genes
Genome-wide association studies (GWAS) have become well-powered to detect loci associated with telomere length. However, no prior work has validated genes nominated by GWAS to examine their role in telomere length regulation. We conducted a multi-ancestry meta-analysis of 211,369 individuals and identified five novel association signals. Enrichment analyses of chromatin state and cell-type heritability suggested that blood/immune cells are the most relevant cell type to examine telomere length association signals. We validated specific GWAS associations by overexpressing KBTBD6 or POP5 and demonstrated that both lengthened telomeres. CRISPR/Cas9 deletion of the predicted causal regions in K562 blood cells reduced expression of these genes, demonstrating that these loci are related to transcriptional regulation of KBTBD6 and POP5. Our results demonstrate the utility of telomere length GWAS in the identification of telomere length regulation mechanisms and validate KBTBD6 and POP5 as genes affecting telomere length regulation
Generalized Carrier Index Differential Chaos Shift Keying Based SWIPT with Conversion Noise and Path Loss-Effect
A generalized carrier index differential chaos shift keying with simultaneous wireless information and power transfer (GCI-DCSK SWIPT) scheme, is proposed, which is an improved scheme for CI-DCSK SWIPT. Compared to CI-DCSK SWIPT, GCI-DCSK SWIPT is not only more flexible in selecting both index bit number and index carrier number, but also is more practical for considering both path loss and the conversion noise generated by radio frequency (RF) band to baseband. The proposed scheme applied a time-switching manner to harvest the energy carried by the inactive carriers. Theoretical bit error rate (BER) expressions of the scheme over AWGN and multipath Rayleigh fading channels are derived, and the ratio of harvested energy to transmitted energy is derived to desecribe the probability of self-sufficiency on power supply. In addition, the frame-derived factor and the energy carried by inactive carriers are optimized to obtain better BER performance. Simulation results show that taking both path loss and conversion noise into consideration, the scheme is still self-sufficient with good BER performance. Furthermore, by adjusting the number of active carriers of GCI-DCSK SWIPT, some cases of GCI-DCSK SWIPT outperform conversion noise-aware CI-DCSK SWIPT in BER
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