Search results for: Aditya Verma

Authors: Zhiwu Zheng, Prakhar Kumar, Sigurd Wagner, Naveen Verma, James C. Sturm

Abstract:

Soft robots have drawn great interest recently due to a rich range of possible shapes and motions they can take on to address new applications, compared to traditional rigid robots. Large-area electronics (LAE) provides a unique platform for creating soft robots by leveraging thin-film technology to enable the integration of a large number of actuators, sensors, and control circuits on flexible sheets. However, the rich shapes and motions possible, especially when interacting with complex environments, pose significant challenges to forming well-generalized and robust models necessary for robot design and control. In this work, we describe an analytical model for predicting the shape and locomotion of a flexible (steel-foil-based) piezoelectric-actuated 2D robot based on Euler-Bernoulli beam theory. It is nominally (unpowered) lying flat on the ground, and when powered, its shape is controlled by an array of piezoelectric thin-film actuators. Key features of the models are its ability to incorporate the significant effects of gravity on the shape and to precisely predict the spatial distribution of friction against the contacting surfaces, necessary for determining inchworm-type motion. We verified the model by developing a distributed discrete element representation of a continuous piezoelectric actuator and by comparing its analytical predictions to discrete-element robot simulations using PyBullet. Without gravity, predicting the shape of a sheet with a linear array of piezoelectric actuators at arbitrary voltages is straightforward. However, gravity significantly distorts the shape of the sheet, causing some segments to flatten against the ground. Our work includes the following contributions: (i) A self-consistent approach was developed to exactly determine which parts of the soft robot are lifted off the ground, and the exact shape of these sections, for an arbitrary array of piezoelectric voltages and configurations. (ii) Inchworm-type motion relies on controlling the relative friction with the ground surface in different sections of the robot. By adding torque-balance to our model and analyzing shear forces, the model can then determine the exact spatial distribution of the vertical force that the ground is exerting on the soft robot. Through this, the spatial distribution of friction forces between ground and robot can be determined. (iii) By combining this spatial friction distribution with the shape of the soft robot, in the function of time as piezoelectric actuator voltages are changed, the inchworm-type locomotion of the robot can be determined. As a practical example, we calculated the performance of a 5-actuator system on a 50-µm thick steel foil. Piezoelectric properties of commercially available thin-film piezoelectric actuators were assumed. The model predicted inchworm motion of up to 200 µm per step. For independent verification, we also modelled the system using PyBullet, a discrete-element robot simulator. To model a continuous thin-film piezoelectric actuator, we broke each actuator into multiple segments, each of which consisted of two rigid arms with appropriate mass connected with a 'motor' whose torque was set by the applied actuator voltage. Excellent agreement between our analytical model and the discrete-element simulator was shown for both for the full deformation shape and motion of the robot.

Keywords: analytical modeling, piezoelectric actuators, soft robot locomotion, thin-film technology

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Authors: Shikha Rani, Neeta Sehgal, Vipin Kumar Verma, Om Prakash

Abstract:

Introduction: Fish is an important protein source for humans and has great economic value. Fish cultures are affected due to various anthropogenic activities that lead to bacterial and viral infections. Aeromonas hydrophila is a fish pathogenic bacterium that causes several aquaculture outbreaks throughout the world and leads to huge mortalities. In this study, plants of no commercial value were used to investigate their immunostimulatory, antioxidant, anti-inflammatory, anti-bacterial, and disease resistance potential in fish against Aeromonas hydrophila, through fish feed fortification. Methods: The plant was dried at room temperature in the shade, dissolved in methanol, and analysed for biological compounds through GC-MS/MS. DPPH, FRAP, Phenolic, and flavonoids were estimated following standardized protocols. In silico molecular docking was also performed to validate its broad-spectrum activities based on binding affinity with specific proteins. Fish were divided into four groups (n=6; total 30 in a group): Group 1, non-challenged fish (fed on a non-supplemented diet); Group 2, fish challenged with bacteria (fed on a non-supplemented diet); Group 3 and 4, fish challenged with bacteria (A. hydrophila) and fed on plant supplemented feed at 2.5% and 5%. Blood was collected from the fish on 0, 7th, 14th, 21st, and 28th days. Serum was separated for glutamic-oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), alkaline phosphatase assay (ALP), lysozyme activity assay, superoxide dismutase assay (SOD), lipid peroxidation assay (LPO) and molecular parameters (including cytokine levels) were estimated through ELISA. The phagocytic activity of macrophages from the spleen and head kidney, along with quantitative analysis of immune-related genes, were analysed in different tissue samples. The digestive enzymes (Pepsin, Trypsin, and Chymotrypsin) were also measured to evaluate the effect of plant-supplemented feed on freshwater fish. Results and Discussion: GC-MS/MS analysis of a methanolic extract of plant validated the presence of key compounds having antioxidant, anti-inflammatory, anti-bacterial, anti-inflammatory, and immunomodulatory activities along with disease resistance properties. From biochemical investigations like ABTS, DPPH, and FRAP, the amount of total flavonoids, phenols, and promising binding affinities towards different proteins in molecular docking analysis helped us to realize the potential of this plant that can be used for investigation in the supplemented feed of fish. Measurement liver function tests, ALPs, oxidation-antioxidant enzyme concentrations, and immunoglobulin concentrations in the experimental groups (3 and 4) showed significant improvement as compared to the positive control group. The histopathological evaluation of the liver, spleen, and head kidney supports the biochemical findings. The isolated macrophages from the group fed on supplemented feed showed a higher percentage of phagocytosis and a phagocytic index, indicating an enhanced cell-mediated immune response. Significant improvements in digestive enzymes were also observed in fish fed on supplemented feed, even after weekly challenges with bacteria. Hence, the plant-fortified feed can be recommended as a regular feed to enhance fish immunity and disease resistance against the Aeromonas hydrophila infection after confirmation from the field trial.

Keywords: immunostimulation, antipathogen, plant fortified feed, macrophages, GC-MS/MS, in silico molecular docking

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Authors: Veenapani Rajeev Verma

Abstract:

Context: Assessing facility readiness is paramount as it can indicate capacity of facilities to provide essential care for resilience to health challenges. In the context of decentralization, estimation of supply side readiness indices at sub national level is imperative for effective evidence based policy but remains a colossal challenge due to lack of dependable and representative data sources. Setting: District Poonch of Jammu and Kashmir was selected for this study. It is remote, rural district with unprecedented topographical barriers and is identified as high priority by government. It is also a fragile area as is bounded by Line of Control with Pakistan bearing the brunt of cease fire violations, military skirmishes and sporadic militant attacks. Hilly geographical terrain, rudimentary/absence of road network and impoverishment are quintessential to this area. Objectives: Objective of the study is to a) Evaluate the service readiness of health facilities and create a concise index subsuming plethora of discrete indicators and b) Ascertain supply side barriers in service provisioning via stakeholder’s analysis. Study also strives to expand analytical domain unravelling context and area specific intricacies associated with service delivery. Methodology: Mixed method approach was employed to triangulate quantitative analysis with qualitative nuances. Facility survey encompassing 90 Subcentres, 44 Primary health centres, 3 Community health centres and 1 District hospital was conducted to gauge general service availability and service specific availability (depth of coverage). Compendium of checklist was designed using Indian Public Health Standards (IPHS) in form of standard core questionnaire and scorecard generated for each facility. Information was collected across dimensions of amenities, equipment, medicines, laboratory and infection control protocols as proposed in WHO’s Service Availability and Readiness Assesment (SARA). Two stage polychoric principal component analysis employed to generate a parsimonious index by coalescing an array of tracer indicators. OLS regression method used to determine factors explaining composite index generated from PCA. Stakeholder analysis was conducted to discern qualitative information. Myriad of techniques like observations, key informant interviews and focus group discussions using semi structured questionnaires on both leaders and laggards were administered for critical stakeholder’s analysis. Results: General readiness score of health facilities was found to be 0.48. Results indicated poorest readiness for subcentres and PHC’s (first point of contact) with composite score of 0.47 and 0.41 respectively. For primary care facilities; principal component was characterized by basic newborn care as well as preparedness for delivery. Results revealed availability of equipment and surgical preparedness having lowest score (0.46 and 0.47) for facilities providing secondary care. Presence of contractual staff, more than 1 hr walk to facility, facilities in zone A (most vulnerable) to cross border shelling and facilities inaccessible due to snowfall and thick jungles was negatively associated with readiness index. Nonchalant staff attitude, unavailability of staff quarters, leakages and constraint in supply chain of drugs and consumables were other impediments identified. Conclusions/Policy Implications: It is pertinent to first strengthen primary care facilities in this setting. Complex dimensions such as geographic barriers, user and provider behavior is not under precinct of this methodology.

Keywords: effective coverage, principal component analysis, readiness index, universal health coverage

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