Stress in a stimuli-responsive polymer brush

The application of a polymer brush in sensing, actuation, self-folding, among others acutely depends on the tuneable bending of a brush-grafted substrate caused by the stress in the brush. However, the stress in a stimuli-responsive brush has not been investigated. In this work, we study the stress in the stimuli-responsive planar polymer brushes of neutral water-soluble polymers with low to very high graft densities using strong stretching theory (SST). First, SST with the Langevin force-extension relation for a polymer chain is extended to the study of stimuli-responsive brushes. Stress profile and other properties of a Poly(N-isopropylacrylamide) (PNIPAm) brush are then obtained using the extended SST and an empirical Flory-Huggins parameter. The model predicts that the stress in a PNIPAm brush is inhomogeneous and compressive at all temperatures and graft densities. The resultant stress is predicted to increase in magnitude with increasing graft density. Moreover, it decreases in magnitude with an increase in temperature before plateauing in low graft density brushes. In contrast, its magnitude increases weakly with increasing temperature in high density brushes. This contrasting behavior is traced to the minimum in interaction free energy density \emph{vs} polymer volume fraction curve for PNIPAm solution at a large volume fraction, and stiffening of chains due to finite extensibility. Furthermore, our results indicate that the ability to tune the resultant stress by changing temperature diminishes with increasing graft density

Stress in a Stimuli-Responsive Polymer Brush

This work studies the stress in stimuli-responsive planar polymer brushes of neutral water-soluble polymers with low to very high graft densities using strong stretching theory (SST). SST with the Langevin force–extension relation for a polymer chain is extended to the study of stimuli-responsive brushes. The stress profile and other structural properties of a poly(N-isopropylacrylamide) (PNIPAm) brush are then obtained using the extended SST and an empirical Flory–Huggins parameter. The swelling ratio predicted by our model is in good qualitative agreement with experimental measurements from the literature. Our model predicts that the stress in a PNIPAm brush is inhomogeneous and compressive at all temperatures and graft densities. The resultant stress is predicted to increase in magnitude with increasing graft density. A temperature increase results in a decrease in the resultant stress magnitude in low graft density brushes but a mild increase in high density brushes. This contrasting behavior arises from the minimum in the interaction free energy density versus polymer volume fraction curve for a PNIPAm solution at a large volume fraction and the stiffening of chains due to finite extensibility. Our results indicate that the ability to tune the resultant stress by changing the temperature diminishes with increasing graft density

Optimal Decentralized Microgrid Coordination via the Schur’s Complement and S-Procedure

The evolving landscape of the electricity sector along with increasing environmental concerns necessitate modern power grids to be more efficient, sustainable, and adaptive. Microgrids are typically composed of distributed energy sources which have great potential for enabling energy independence, sustainability, and flexibility. However, practical difficulties that deter the widespread deployment of microgrids include the unpredictability of local generation sources (e.g., renewables) and the lack of inertia that is naturally present in systems containing bulk synchronous plants. In this paper, we propose a near real-time microgrid coordination algorithm that allows actuating components to adapt to changing system conditions. We account for the electrical dependencies and limits in microgrid systems by constructing voltage/current balance relations in the dq0 frame and applying strategic decompositions to invoke the Schur's complement and S-procedure that allow for zero duality gap. We highlight the convergence, feasibility, and scalability features of the proposed decentralized algorithm via theoretical and comparative practical simulation studies

Hidden Convexities in Decentralized Coordination for the Distribution Networks

The modern power grid is undergoing unprecedented levels of transformations due to the rising prevalence of diverse power entities, cyber-enablement of grid components and energy deregulations. In this paper, we focus on distribution networks (DNs) to enable the seamless plug-and-play coordination of actuating cyber-enabled power entities for cost-effective and feasible system operations. The proposed distributed algorithm empowers individual cyber-physical agents residing in active power nodes with the ability to iteratively compute local actuation setpoints by exchanging information with neighbouring entities. The main contribution of this work is the identification of hidden convexities in the original non-convex optimal power flow (OPF) formulation for the DN via strategic decomposition and strong duality principles. These eliminate the need for OPF relaxations/approximations. Strong convergence and feasibility results are presented via theoretical analysis and practical simulation studies conducted on realistic systems

Array comparative genomic hybridization: results from an adult population with drug-resistant epilepsy and co-morbidities.

The emergence of array comparative genomic hybridization (array CGH) as a diagnostic tool in molecular genetics has facilitated recognition of microdeletions and microduplications as risk factors for both generalised and focal epilepsies. Furthermore, there is evidence that some microdeletions/duplications, such as the 15q13.3 deletion predispose to a range of neuropsychiatric disorders, including intellectual disability (ID), autism, schizophrenia and epilepsy. We hypothesised that array CGH would reveal relevant findings in an adult patient group with epilepsy and complex phenotypes

Governance of Benefits from Developmental Programmes to Farmers in Karnataka

There are umpteen number of developmental programmes concentrating on poor. However, at no single place, a list of these programmes offered by Government, NGOs and other agencies are available. This study has the objective of documenting and analysing the developmental programmes/schemes in vogue, benefits rcfeived, difficulties faced in availing the benefits of developmental programmetnd the transaction costs incurred to avail the benefit in the rural and peri-urba areas of Bangalore metropolis surrounding Magadi. For this study, a sample of 0 farmers from peri urban (Magadi town area) and another sample of 50 farmers from rural area (Halasabele village Magadi) have been chosen, to have comparison between the benefits of developmental programmes received by the farmers in peri-urban areas with that of farmers of rural area. Magadi town is well connected with Bangalore metropolis by a new asphalted road. Halasabele village is included in the sample as the rural village located 20 kms away from Magadi town on the way to Kunigal, with relatively low urban or peri-urban influence. A litmus test for the apparent difference between peri-urban and rural area lies in the market value of land of Rs. 2 million per acre in peri urban Magadi and Rs.O.S to 0.6 million per acre in rural area of Halasabele, pointing to a difference of around 300 per cent. The sample farmers were chosen to include 25 farmers with irrigation facility and 25 farmers without irrigation facility with the hypothesis that irrigation confers higher benefits. It is also hypothesised that the governance of developmental programmes is indicated by the magnitude of transaction cost

Economic Impacts of MGNREGA in Dryland Region of India: A Meso and Micro Study in Selected States

This chapter assesses impacts of MGNREGA in selected six states and selected sample households in four districts of Karnataka, covering both macro level and micro scale analysis. We analyze data on whether MGNREGA programme has been successful in providing 100 days of employment per annum to rural poor households, and to what extent the MGNREGA has offered social protection to the rural poor. Likewise, whether increase in agricultural labour wage rate in recent years is due to introduction of MGNREGS. The results indicate that at the macro level, the performance of MGNREGA is not even across the six dryland states selected here, even after a decade of its implementation. Only 7–12% of the households could receive 100 days of employment from MGNREGA in the six states studied. In Karnataka, over 60% of households were provided employment for less than 60 days. It was observed that the benefits obtained are largely at the community level through asset creation that includes desiltation of irrigation tanks, rural connectivity and construction of school buildings. Though MGNREGA works were able to assure sustainable development through improved Natural Resource Management in some regions, it failed in providing social protection where the leadership of implementing agencies was weak and lack of dynamism. Stringent rules and regulations resulted in inordinate delays in executing works and making timely payment of wages to workers. Addressing these issues in the implementation of MGNREGS would enhance its multi-dimensional impacts on rural poor across the India, and ensuring for sustainable development in rural India

Using an Ishikawa diagram as a tool to assist memory and retrieval of relevant medical cases from the medical literature

<p>Abstract</p> <p>Studying medical cases is an effective way to enhance clinical reasoning skills and reinforce clinical knowledge. An Ishikawa diagram, also known as a cause-and-effect diagram or fishbone diagram, is often used in quality management in manufacturing industries.</p> <p>In this report, an Ishikawa diagram is used to demonstrate how to relate potential causes of a major presenting problem in a clinical setting. This tool can be used by teams in problem-based learning or in self-directed learning settings.</p> <p>An Ishikawa diagram annotated with references to relevant medical cases and literature can be continually updated and can assist memory and retrieval of relevant medical cases and literature. It could also be used to cultivate a lifelong learning habit in medical professionals.</p