24 research outputs found
Learning Sparsity-Promoting Regularizers using Bilevel Optimization
We present a method for supervised learning of sparsity-promoting
regularizers for denoising signals and images. Sparsity-promoting
regularization is a key ingredient in solving modern signal reconstruction
problems; however, the operators underlying these regularizers are usually
either designed by hand or learned from data in an unsupervised way. The recent
success of supervised learning (mainly convolutional neural networks) in
solving image reconstruction problems suggests that it could be a fruitful
approach to designing regularizers. Towards this end, we propose to denoise
signals using a variational formulation with a parametric, sparsity-promoting
regularizer, where the parameters of the regularizer are learned to minimize
the mean squared error of reconstructions on a training set of ground truth
image and measurement pairs. Training involves solving a challenging bilievel
optimization problem; we derive an expression for the gradient of the training
loss using the closed-form solution of the denoising problem and provide an
accompanying gradient descent algorithm to minimize it. Our experiments with
structured 1D signals and natural images show that the proposed method can
learn an operator that outperforms well-known regularizers (total variation,
DCT-sparsity, and unsupervised dictionary learning) and collaborative filtering
for denoising. While the approach we present is specific to denoising, we
believe that it could be adapted to the larger class of inverse problems with
linear measurement models, giving it applicability in a wide range of signal
reconstruction settings
Pandemic Politics in Eurasia:Roadmap for a New Research Subfield
© 2020 Taylor & Francis Group, LLC. The sudden onset of COVID-19 has challenged many social scientists to proceed without a robust theoretical and empirical foundation upon which to build. Addressing this challenge, particularly as it pertains to Eurasia, our multinational group of scholars draws on past and ongoing research to suggest a roadmap for a new pandemic politics research subfield. Key research questions include not only how states are responding to the new coronavirus, but also reciprocal interactions between the pandemic and society, political economy, regime type, center-periphery relations, and international security. The Foucauldian concept of âbiopoliticsâ holds out particular promise as a theoretical framework
Pandemic Politics in Eurasia:Roadmap for a New Research Subfield
The sudden onset of the coronavirus pandemic has challenged many scholars of the social sciences to proceed in the absence of a robust theoretical research foundation upon which to build. This article seeks to help scholars meet this challenge, particularly as it pertains to Eurasia, through bringing together a multinational group of scholars in order to develop the roadmap for a new pandemic politics research subfield. It begins with a discussion of how states are responding to COVID-19 before moving into an exploration of reciprocal interactions between the pandemic and society, political economy, regime type, center-periphery relations, and international security. Finally, it discusses the potential novel contributions of a theoretical foundation rooted in the Foucauldian concept of âbiopolitics.â Ultimately, we hope to spark an ongoing conversation regarding how political science and the social sciences more broadly can be used to understand the impacts of the pandemic and inform policymaking amidst the current and potential future pandemics
Finishing the euchromatic sequence of the human genome
The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers âŒ99% of the euchromatic genome and is accurate to an error rate of âŒ1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead
The IDENTIFY study: the investigation and detection of urological neoplasia in patients referred with suspected urinary tract cancer - a multicentre observational study
Objective
To evaluate the contemporary prevalence of urinary tract cancer (bladder cancer, upper tract urothelial cancer [UTUC] and renal cancer) in patients referred to secondary care with haematuria, adjusted for established patient risk markers and geographical variation.
Patients and Methods
This was an international multicentre prospective observational study. We included patients aged â„16 years, referred to secondary care with suspected urinary tract cancer. Patients with a known or previous urological malignancy were excluded. We estimated the prevalence of bladder cancer, UTUC, renal cancer and prostate cancer; stratified by age, type of haematuria, sex, and smoking. We used a multivariable mixed-effects logistic regression to adjust cancer prevalence for age, type of haematuria, sex, smoking, hospitals, and countries.
Results
Of the 11 059 patients assessed for eligibility, 10 896 were included from 110 hospitals across 26 countries. The overall adjusted cancer prevalence (n = 2257) was 28.2% (95% confidence interval [CI] 22.3â34.1), bladder cancer (n = 1951) 24.7% (95% CI 19.1â30.2), UTUC (n = 128) 1.14% (95% CI 0.77â1.52), renal cancer (n = 107) 1.05% (95% CI 0.80â1.29), and prostate cancer (n = 124) 1.75% (95% CI 1.32â2.18). The odds ratios for patient risk markers in the model for all cancers were: age 1.04 (95% CI 1.03â1.05; P < 0.001), visible haematuria 3.47 (95% CI 2.90â4.15; P < 0.001), male sex 1.30 (95% CI 1.14â1.50; P < 0.001), and smoking 2.70 (95% CI 2.30â3.18; P < 0.001).
Conclusions
A better understanding of cancer prevalence across an international population is required to inform clinical guidelines. We are the first to report urinary tract cancer prevalence across an international population in patients referred to secondary care, adjusted for patient risk markers and geographical variation. Bladder cancer was the most prevalent disease. Visible haematuria was the strongest predictor for urinary tract cancer
Genomic Dissection of Bipolar Disorder and Schizophrenia, Including 28 Subphenotypes
publisher: Elsevier articletitle: Genomic Dissection of Bipolar Disorder and Schizophrenia, Including 28 Subphenotypes journaltitle: Cell articlelink: https://doi.org/10.1016/j.cell.2018.05.046 content_type: article copyright: © 2018 Elsevier Inc
Chemotherapeutically driven p21 induction leads to aberrant regulation of MAD2 by miR-433 and results in the ability of epithelial ovarian cancer cells to bypass apoptosis
Overexpression of the microRNA miR-433 promotes resistance to paclitaxel through the induction of cellular senescence in ovarian cancer cells
Annually, ovarian cancer (OC) affects 240,000 women worldwide and is the most lethal gynecological malignancy. High-grade serous OC (HGSOC) is the most common and aggressive OC subtype, characterized by widespread genome changes and chromosomal instability and is consequently poorly responsive to chemotherapy treatment. The objective of this study was to investigate the role of the microRNA miR-433 in the cellular response of OC cells to paclitaxel treatment. We show that stable miR-433 expression in A2780 OC cells results in the induction of cellular senescence demonstrated by morphological changes, downregulation of phosphorylated retinoblastoma (p-Rb), and an increase in ÎČ-galactosidase activity. Furthermore, in silico analysis identified four possible miR-433 target genes associated with cellular senescence: cyclin-dependent kinase 6 (CDK6), MAPK14, E2F3, and CDKN2A. Mechanistically, we demonstrate that downregulation of p-Rb is attributable to a miR-433-dependent downregulation of CDK6, establishing it as a novel miR-433 associated gene. Interestingly, we show that high miR-433 expressing cells release miR-433 into the growth media via exosomes which in turn can induce a senescence bystander effect. Furthermore, in relation to a chemotherapeutic response, quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that only PEO1 and PEO4 OC cells with the highest miR-433 expression survive paclitaxel treatment. Our data highlight how the aberrant expression of miR-433 can adversely affect intracellular signaling to mediate chemoresistance in OC cells by driving cellular senescence.Health Research BoardMater Surgical Oncology Appea