Accelerated Algorithms for a Class of Optimization Problems with Equality and Box Constraints

Convex optimization with equality and inequality constraints is a ubiquitous problem in several optimization and control problems in large-scale systems. Recently there has been a lot of interest in establishing accelerated convergence of the loss function. A class of high-order tuners was recently proposed in an effort to lead to accelerated convergence for the case when no constraints are present. In this paper, we propose a new high-order tuner that can accommodate the presence of equality constraints. In order to accommodate the underlying box constraints, time-varying gains are introduced in the high-order tuner which leverage convexity and ensure anytime feasibility of the constraints. Numerical examples are provided to support the theoretical derivations.Comment: 6 pages, accepted in ACC 2023 (American Control Conference, 2023

Accelerated algorithms for constrained optimization and control

Nonlinear optimization with equality and inequality constraints is a ubiquitous problem in several optimization and control problems in large-scale systems. Ensuring feasibility along with reasonable convergence to optimal solution remains an open and pressing problem in this area. A class of high-order tuners was recently proposed in adaptive control literature with an effort to lead to accelerated convergence for the case when no constraints are present. In this thesis, we propose a new high-order tuner based algorithm that can accommodate the presence of equality and inequality constraints. We leverage the linear dependence in solution space to guarantee that equality constraints are always satisfied. We further ensure feasibility with respect to inequality constraints for the specific case of box constraints by introducing time-varying gains in the high-order tuner while retaining the attractive accelerated convergence properties. Theoretical guarantees pertaining to stability are also provided for time-varying regressors. These theoretical propositions are validated by applying them to several categories of optimization problems, in the form of academic examples, power flow optimization and neural network optimization. We devote special attention to analyze a special case of neural network optimization, namely, linear neural network training problem, to understand the dynamics of nonconvex optimization governed by gradient flow and provide lyapunov stability guarantees for LNNs.S.M

Accelerated Algorithms for a Class of Optimization Problems with Constraints

This paper presents a framework to solve constrained optimization problems in an accelerated manner based on High-Order Tuners (HT). Our approach is based on reformulating the original constrained problem as the unconstrained optimization of a loss function. We start with convex optimization problems and identify the conditions under which the loss function is convex. Building on the insight that the loss function could be convex even if the original optimization problem is not, we extend our approach to a class of nonconvex optimization problems. The use of a HT together with this approach enables us to achieve a convergence rate better than state-of-the-art gradient-based methods. Moreover, for equality-constrained optimization problems, the proposed method ensures that the state remains feasible throughout the evolution, regardless of the convexity of the original problem.Comment: 6 page

An interplay between MicroRNA and SOX4 in the regulation of epithelial–mesenchymal transition and cancer progression

MicroRNAs (miRNAs) are abundant class of small, noncoding RNAs which are emerging as a potential therapeutic target for various cancers. Sex-determining region Y-related high-mobility group box 4 (SOX4) is an important member of SOX family and a crucial master regulator of epithelial–mesenchymal transition (EMT) that has been implicated in tumor growth and progression. In cancers of epithelial origin and in some others, growing evidence has revealed a close association between miRNAs and SOX4. Most miRNAs are reported to modulate SOX4 by directly binding to SOX4 3'-untranslated region, thereby regulating cancer cell proliferation, invasion, and EMT. In this review, we highlight the interaction of miRNAs with SOX4 in various cancers and discuss the possibility of combined miRNA-SOX4-based therapeutic approach that may serve as a targeted therapy for several cancers

Validity of madras diabetes research foundation: Indian diabetes risk score for screening of diabetes mellitus among adult population of urban field practice area, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India

Introduction: IDRS is based on four simple parameters derived from known risk factors for diabetes; two modifiable risk factors (waist circumference and physical inactivity) and two non-modifiable risk factors (age and family history of diabetes), which may be amenable to intervention. The present study has been planned as the region specific validation is important before it can be used for screening in this part of the country. Aims: The aim of the present study was to validate MDRF-IDRS for screening of diabetes mellitus among adult population of urban field practice area, IGMC, Shimla, Himachal Pradesh, India. Methods: The present community based cross sectional study was conducted among 417 adults fulfilling the eligibility criteria using a two stage sampling design. Results: In the present study IDRS value ≥70 had an optimum sensitivity of 61.33% and specificity of 56.14% for detecting undiagnosed type 2 diabetes in the community. At an IDRS score of ≥70, the PPV was 23.47%, NPV as 86.88%, the diagnostic accuracy as 57.07%, LR for positive test as 1.398, LR for negative test as 0.69 and Youden's index as 0.17. However Youden's index was 0.19 at a cut of ≥60 i.e. higher than what was at ≥70. Higher IDRS scores increased the specificity but the sensitivity dramatically decreased. Conversely, lower IDRS values increased the sensitivity but the specificity drastically decreased. Area under the curve = 0.630 and a P value < 0.001. Conclusions: MDRF IDRS is user friendly screening tool but the criteria of including the parameter of physical activity for the calculation of the risk score needs to be clearly defined. In the present study the maximum sensitivity of 100% was seen at a cut off of ≥30. Hence we would recommend that all those in the medium and high risk group should be screened for type 2 Diabetes

Patient-Derived Ovarian Cancer Spheroids Rely on PI3K-AKT Signaling Addiction for Cancer Stemness and Chemoresistance

Ovarian cancer is the most lethal gynecological malignancy among women worldwide and is characterized by aggressiveness, cancer stemness, and frequent relapse due to resistance to platinum-based therapy. Ovarian cancer cells metastasize through ascites fluid as 3D spheroids which are more resistant to apoptosis and chemotherapeutic agents. However, the precise mechanism as an oncogenic addiction that makes 3D spheroids resistant to apoptosis and chemotherapeutic agents is not understood. To study the signaling addiction mechanism that occurs during cancer progression in patients, we developed an endometrioid subtype ovarian cancer cell line named ‘MCW-OV-SL-3’ from the ovary of a 70-year-old patient with stage 1A endometrioid adenocarcinoma of the ovary. We found that the cell line MCW-OV-SL-3 exhibits interstitial duplication of 1q (q21–q42), where this duplication resulted in high expression of the PIK3C2B gene and aberrant activation of PI3K-AKT-ERK signaling. Using short tandem repeat (STR) analysis, we demonstrated that the cell line exhibits a unique genetic identity compared to existing ovarian cancer cell lines. Notably, the MCW-OV-SL-3 cell line was able to form 3D spheroids spontaneously, which is an inherent property of tumor cells when plated on cell culture dishes. Importantly, the tumor spheroids derived from the MCW-OV-SL-3 cell line expressed high levels of c-Kit, PROM1, ZEB1, SNAI, VIM, and Twist1 compared to 2D monolayer cells. We also observed that the hyperactivation of ERK and PI3K/AKT signaling in these cancer cells resulted in resistance to cisplatin. In summary, the MCW-OV-SL3 endometrioid cell line is an excellent model to study the mechanism of cancer stemness and chemoresistance in endometrioid ovarian cancer

Correction: Parashar et al. Patient-Derived Ovarian Cancer Spheroids Rely on PI3K-AKT Signaling Addiction for Cancer Stemness and Chemoresistance. Cancers 2022, 14, 958

The authors would like to correct the author byline to include Dr [...