Unraveling the link between severe bradycardia and paraquat poisoning

Ramkumar Anitha,Murthy Tatavarti,Elanjeran Rajkumar,Chaitanya Y. Vishnu,Harika Kari,Mahalingam Sasikumar,Rajendiran Gunaseelan 대한응급의학회 2024 Clinical and Experimental Emergency Medicine Vol.11 No.1

Coupled temperature-displacement modeling to study the thermo-elastic instability in disc brakes

Ramkumar, E.,Mayuram, M.M. Techno-Press 2012 Coupled systems mechanics Vol.1 No.2

Macroscopic hot spots formed due to the large thermal gradients at the surface of the disc brake rotor, make the rotor to fail or wear out early. Thermo-elastic deformation results in contact concentration, leading to the non uniform distribution of temperature making the disc susceptible to hot spot formation. The formation of one hot spot event will predispose the system to future hot spotting at the same location. This leads to the complete thermo-elastic instability in the disc brakes; multitude parameters are responsible for the thermo elastic instability. The predominant factor is the sliding velocity and above a certain sliding velocity the instability of the brake system occurs and hot spots is formed in the surface of the disc brake. Commercial finite element package ABAQUS(R) is used to find the temperature distribution and the result is validated using Rowson's analytical model. A coupled analysis methodology is evolved for the automotive disc brake from the transient thermo-elastic contact analysis. Temperature variation is studied under different sliding speeds within the operation range.

A Tinnitus Inventory Focusing on Body Function, Activities, and Participation Using the International Classification of Functioning, Disability and Health

Ramkumar Vidya,Chandrasekaran Anitha 대한청각학회 2023 Journal of Audiology & Otology Vol.27 No.2

Background and Objectives: This study describes the development of an International Classification for Functioning, Disability and Health (ICF)-based inventory for tinnitus (ICF-TINI) that measures the impact of tinnitus on the function, activities, and participation of an individual.Subjects and Methods: This cross-sectional study utilized the ICF-TINI, which included 15 items from the two ICF components of body function and activities. We included 137 respondents with chronic tinnitus. Confirmatory factor analysis validated the two-structure framework (body function, activities and participation). The model fit was assessed by comparing fit values of chi-square (df), root mean square error of approximation, comparative fit index, incremental fit index, and Tucker-Lewis index, with the suggested fit criteria values. Cronbach’s alpha was used to assess internal consistency reliability.Results: The fit indices confirmed the presence of two structures in ICF-TINI, while the factor loading values suggested each item’s goodness of fit. The ICF-internal TINI exhibited high consistency reliability (0.93).Conclusions: The ICFTINI is a reliable and valid tool for assessing the impact of tinnitus on an individual’s body function, activities, and participation.

Initiation of human parturition: signaling from senescent fetal tissues via extracellular vesicle mediated paracrine mechanism

Ramkumar Menon 대한산부인과학회 2019 Obstetrics & Gynecology Science Vol.62 No.4

A better understanding of the underlying mechanisms by which signals from the fetus initiate human parturitionis required. Our recent findings support the core hypothesis that oxidative stress (OS) and cellular senescence ofthe fetal membranes (amnion and chorion) trigger human parturition. Fetal membrane cell senescence at term is anatural physiological response to OS that occurs as a result of increased metabolic demands by the maturing fetus. Fetal membrane senescence is affected by the activation of the p38 mitogen activated kinase-mediated pathway. Similarly, various risk factors of preterm labor and premature rupture of the membranes also cause OS-inducedsenescence. Data suggest that fetal cell senescence causes inflammatory senescence-associated secretory phenotype(SASP) release. Besides SASP, high mobility group box 1 and cell-free fetal telomere fragments translocate from thenucleus to the cytosol in senescent cells, where they represent damage-associated molecular pattern markers (DAMPs). In fetal membranes, both SASPs and DAMPs augment fetal cell senescence and an associated ‘sterile’ inflammatoryreaction. In senescent cells, DAMPs are encapsulated in extracellular vesicles, specifically exosomes, which are 30–150nm particles, and propagated to distant sites. Exosomes traffic from the fetus to the maternal side and cause laborassociatedinflammatory changes in maternal uterine tissues. Thus, fetal membrane senescence and the inflammationgenerated from this process functions as a paracrine signaling system during parturition. A better understandingof the premature activation of these signals can provide insights into the mechanisms by which fetal signals initiatepreterm parturition.

Quantum-Dot and Polychalcone Mixed Nanocomposites for Polymer Light-Emitting Diodes

Ramkumar, Vanaraj,Ju, Sanghyun Hindawi Limited 2017 Journal of nanomaterials Vol.2017 No.-

<P>The present work is aimed at improving the efficiency of light-emitting diodes (LEDs) through the amalgamation of polymeric materials and quantum dots (QDs) in nanocomposites. Herein, we report on the polytriphenylamine-based chalcone (PTpC) or polycarbazole-based chalcone- (PCzC-) QDs mixture nanocomposites as emissive layers for polymer LEDs (PLEDs). QDs were evenly dispersed in the polymer matrix and the synthesized PTpC-QDs and PCzC-QDs nanocomposites were able to form smooth thin films. The luminance characteristics of PTpC-QDs and PCzC-QDs nanocomposites were better than those of the pristine QD, PTpC, and PCzC materials, owing to the high charge-carrier transport ability of polymer-QDs nanocomposites. These results indicate that the proposed polymer-QDs nanocomposites could be potential candidates for application in PLEDs.</P>

Optimization of operating parameters and performance evaluation of forced draft cooling tower using response surface methodology (RSM) and artificial neural network (ANN)

Ramkumar Ramakrishnan,Ragupathy Arumugam 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"Optimization of cold water temperature in forced draft cooling tower with various operating parameters has been considered in the present work. In this study, response surface method (RSM) and an artificial neural network (ANN) were developed to predict cold water temperature in forced draft cooling tower. In the development of predictive models, water flow, air flow, water temperature and packing height were considered as model variables. For this propose, an experiment based on statistical five-level four factorial design of experiments method was carried out in the forced draft cooling tower. Based on statistical analysis, packing height, air flow and water flow were high significant effects on cold water temperature, with very low probability values (< 0.0001). The optimum operating parameters were predicted using RSM, ANN model and confirmed through experiments. The result demonstrated that minimum cold water temperature was optioned from the ANN model compared with RSM."

Epithelial to mesenchymal transition (EMT) of feto-maternal reproductive tissues generates inflammation: a detrimental factor for preterm birth

Ramkumar Menon 생화학분자생물학회 2022 BMB Reports Vol.55 No.8

Human pregnancy is a delicate and complex process wheremultiorgan interactions between two independent systems, themother, and her fetus, maintain pregnancy. Intercellular interactionsthat can define homeostasis at the various cellular levelbetween the two systems allow uninterrupted fetal growth anddevelopment until delivery. Interactions are needed for tissueremodeling during pregnancy at both fetal and maternal tissuelayers. One of the mechanisms that help tissue remodeling isvia cellular transitions where epithelial cells undergo a cyclictransition from epithelial to mesenchymal (EMT) and back frommesenchymal to epithelial (MET). Two major pregnancy-associatedtissue systems that use EMT, and MET are the fetal membrane(amniochorion) amnion epithelial layer and cervical epithelialcells and will be reviewed here. EMT is often associatedwith localized inflammation, and it is a well-balanced processto facilitate tissue remodeling. Cyclic transition processes areimportant because a terminal state or the static state of EMTcan cause accumulation of proinflammatory mesenchymal cellsin the matrix regions of these tissues and increase localizedinflammation that can cause tissue damage. Interactions thatdetermine homeostasis are often controlled by both endocrineand paracrine mediators. Pregnancy maintenance hormoneprogesterone and its receptors are critical for maintaining thebalance between EMT and MET. Increased intrauterine oxidativestress at term can force a static (terminal) EMT and increaseinflammation that are physiologic processes that destabilizehomeostasis that maintain pregnancy to promote labor and deliveryof the fetus. However, conditions that can produce anuntimely increase in EMT and inflammation can be pathologic. These tissue damages are often associated with adverse pregnancycomplications such as preterm prelabor rupture of themembranes (pPROM) and spontaneous preterm birth (PTB). Therefore, an understanding of the biomolecular processes thatmaintain cyclic EMT-MET is critical to reducing the risk ofpPROM and PTB. Extracellular vesicles (exosomes of 40-160nm) that can carry various cargo are involved in cellular transitionsas paracrine mediators. Exosomes can carry a variety ofbiomolecules as cargo. Studies specifically using exosomes fromcells undergone EMT can carry a pro-inflammatory cargo andin a paracrine fashion can modify the neighboring tissue environmentto cause enhancement of uterine inflammation.

Influence of light qualities on antifungal lipopeptide synthesis in Bacillus amyloliquefaciens JBC36

Ramkumar, Gandhimani,Yu, Sang-Mi,Lee, Yong Hoon Springer-Verlag 2013 European Journal of Plant Pathology Vol.137 No.2

Modeling consumers’ intention to use fashion and beauty subscription‑based online services (SOS)

Bharath Ramkumar,우홍주 한국의류학회 2018 Fashion and Textiles Vol.5 No.1

This study examined one of the new consumption styles of modern consumers, subscription-based online services (SOS), which is often called as box retailing. The purpose of this study was to empirically test six antecedents—utilitarian motivations, hedonic motivations, fashion consciousness, consumer innovativeness, desire for unique products, and online transaction self-efficacy—as predictors of consumers’ attitude toward and intention to use fashion/beauty SOS. The theory of reasoned action was used as a theoretical foundation. With responses from 385 American consumers on an online survey, the theoretical model was tested in the fashion/beauty SOS context using structural equation modeling on LISREL. Results indicated that utilitarian and hedonic motivations, fashion consciousness, and online transaction self-efficacy indirectly influence intention to use fashion/beauty SOS, mediated by attitude towards fashion/beauty SOS. Instead of being mediated by attitude towards fashion/beauty SOS, consumer innovativeness and desire for unique products directly influence intention to use fashion/beauty SOS. Subjective norm positively influences intention to use fashion/beauty SOS. By identifying the factors that can predict consumers’ attitude towards and intention to use this new type of fashion/beauty consumption, this study addresses an evolving trend in home-based shopping behavior. Theoretically, as one of the earliest studies in this phenomenon, this study lays the theoretical groundwork paving way for further exploration in this area. Managers of fashion and beauty SOSs also can utilize these findings to more accurately target the appropriate consumer segment and streamline their marketing messages in accordance.

Controllability of impulsive neutral stochastic functional integrodifferential system via resolvent operator

K. Ramkumar,K. Ravikumar,Dimplekumar Chalishajar,A. Anguraj,Mamadou Abdoul Diop 한국전산응용수학회 2023 Journal of Applied and Pure Mathematics Vol.5 No.1

This paper is concerned by the controllability results of impulsive neutral stochastic functional integrodifferential equations (INSFIDEs) driven by fractional Brownian motion with infinite delay in a real separable Hilbert space. The controllability results are obtained using stochastic analysis, Krasnoselkii fixed point method and the theory of resolvent operator in the sense of Grimmer. A practical example is provided to illustrate the viability of the abstract result of this work.