Do Neural Topic Models Really Need Dropout? Analysis of the Effect of Dropout in Topic Modeling

Dropout is a widely used regularization trick to resolve the overfitting issue in large feedforward neural networks trained on a small dataset, which performs poorly on the held-out test subset. Although the effectiveness of this regularization trick has been extensively studied for convolutional neural networks, there is a lack of analysis of it for unsupervised models and in particular, VAE-based neural topic models. In this paper, we have analyzed the consequences of dropout in the encoder as well as in the decoder of the VAE architecture in three widely used neural topic models, namely, contextualized topic model (CTM), ProdLDA, and embedded topic model (ETM) using four publicly available datasets. We characterize the dropout effect on these models in terms of the quality and predictive performance of the generated topics.Comment: Accepted at EACL 202

Improving Contextualized Topic Models with Negative Sampling

Topic modeling has emerged as a dominant method for exploring large document collections. Recent approaches to topic modeling use large contextualized language models and variational autoencoders. In this paper, we propose a negative sampling mechanism for a contextualized topic model to improve the quality of the generated topics. In particular, during model training, we perturb the generated document-topic vector and use a triplet loss to encourage the document reconstructed from the correct document-topic vector to be similar to the input document and dissimilar to the document reconstructed from the perturbed vector. Experiments for different topic counts on three publicly available benchmark datasets show that in most cases, our approach leads to an increase in topic coherence over that of the baselines. Our model also achieves very high topic diversity.Comment: Accepted at 19th International Conference on Natural Language Processing (ICON 2022

A Study of Antepartum Cardiotocography in Mothers with Reduced Fetal Movement at Term and Its Correlation with Fetal Outcome

Maternal perception of fetal movement is one of the first signs of fetal life and is regarded as a manifestation of fetal wellbeing. Reduced or absent fetal movements may be a warning sign of impending fetal death. According to the various tracingsobtained on cardiotocography (CTG), categorization can be done into normal, suspicious or abnormal/pathological and therebyfetal jeopardy can be reliably predicted. This study was designed to evaluate the CTG findings in mothers with complaint ofreduced fetal movement and their fetal outcome at term. It was seen that abnormal and suspicious CTG were more commonlyassociated with meconium-stained liquor at delivery; also they were associated with a higher rate of cesarean section with fetaldistress being the most common indication among these two groups

Freelance Orientation in the Sharing Economy: Evidence from Labor Platforms

Sharing economy labor platforms depend on a voluntary freelance workforce to provide professional or personal services. These platforms cite high freelancer turnover and performance variance as major concerns. Both these concerns affect the platform’s customer experience, network growth, and brand image. Prior research proposes extrinsic retention approaches such as incentive-based (e.g., higher pay for better performance) and value-based job resources (e.g., enhanced support through training). The financial precariousness of the labor platforms leaves them with limited scope to pursue costly extrinsic retention strategies. Our study focuses on the freelancer’s intrinsic personal resources such as psychological traits within a specific occupational context (professional/personal services) as an alternate yet complimentary cost-efficient way to alleviate the concerns. Influenced by the job-demand resources model, we use exploratory techniques to find customer orientation, self-efficacy, proactivity through strategic emphasis, and risk-taking propensity as orientation traits that makes individuals suitable for freelancing. Confirmatory surveys confirm that the orientation traits predict work engagement. Further, the twin outcomes of freelancer’s work performance and intention to turnover are partially mediated by freelancer’s work engagement. Customer feedback in the form of reviews positively moderates the relationship between work engagement and work performance. Platform managers can identify and retain freelance-oriented workers through strategic resource allocation, saving acquisition and branding expenses while growing revenue through enhanced customer experience and transactions

Proteasome dysfunction under compromised redox metabolism dictates liver injury in NASH through ASK1/PPARγ binodal complementary modules

Incidence of hepatotoxicity following acute drug-induced proteasomal inhibition and development of chronic proteasome dysfunction in obesity and insulin resistance underscores the crucial importance of hepatic protein homeostasis albeit with an elusive molecular basis and therapeutic opportunities. Apart from lipotoxicity and endoplasmic reticulum (ER) stress, herein we report that hepatocytes are highly susceptible to proteasome-associated metabolic stress attune to altered redox homeostasis. Bortezomib-induced proteasomal inhibition caused severe hepatocellular injury independent of ER stress via proapoptotic Apoptosis Signal-regulating Kinase 1 (ASK1)- c-Jun N-terminal kinase (JNK1)- p38 signaling concomitant with inadequate peroxisome proliferator-activated receptor γ (PPARγ)- Nuclear factor erythroid 2-related factor 2 (Nrf2) -driven antioxidant response. Although inhibition of ASK1 rescued acute hepatotoxicity, hepatic depletion of PPARγ or its physiological activator pigment epithelium-derived factor (PEDF) further aggravated liver injury even under ASK1 inhibition, emphasizing that endogenous PPARγ driven antioxidant activity serves as a prerequisite for the favorable therapeutic outcome of ASK1 inhibition. Consequently, ASK1 inhibitor selonsertib and PPARγ agonist pioglitazone in pharmacological synergism ameliorated bortezomib-induced hepatotoxicity and significantly prolonged survival duration in mice. Moreover, we showed that proteasome dysfunction is associated with ASK1 activation and insufficient PPARγ/Nrf2-driven antioxidative response in a subset of human nonalcoholic steatohepatitis (NASH) patients and the preclinical NASH model. The latter remains highly responsive to the drug combination marked by revamped proteasomal activity and alleviated hallmarks of NASH such as steatosis, fibrosis, and hepatocellular death. We thus uncovered a pharmacologically amenable interdependent binodal molecular circuit underlying hepatic proteasomal dysfunction and associated oxidative injury