Interactive substrate for bone regeneration

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.Includes bibliographical references (leaves 59-68).Current methods of bone repair rely on autografts (bone from a donor site) and allografts (bone from human cadaver). However, these methods are plagued with disadvantages. There is a clear and urgent need to provide alternatives for regenerating and repairing bone. Bone is known to be one of the many connective tissues in the body that are responsive to exogenous electrical stimulation. Based on this principle, this thesis explores the potential of using an electrically conducting polymer, polypyrrole, as a substrate for bone regeneration. Optically transparent thin films of polypyrrole, with a polyanionic dopant, poly(styrenesulfonate), were synthesized electrochemically and characterized by X-Ray Photoelectron Spectroscopy, UV/VIS spectroscopy, Scanning Electron Microscopy and by electrical conductivity measurements. In this study, Bone Marrow Stromal Cells (BMSC), which are the progenitor cells to bone cells (osteoblasts), were used as the in vitro model system. Their viability, proliferation and differentiation capabilities were evaluated on polypyrrole, in the absence and presence of electrical stimulation. Results indicate that polypyrrole is ideally suited as a substratum for BMSC growth and differentiation. The application of an electrical stimulus through the polypyrrole substrate was found to induce the differentiation of BMSC towards an osteogenic lineage. Thus, polypyrrole, by virtue of its conductive properties, its in vitro biocompatibility and its flexibility in altering surface characteristics, has an exciting potential as a suitable interactive substrate for bone regeneration.by Nahid Rahman.S.M

Impact on Voice after Cervical Spinal Cord Injury

Spinal Cord Injury (SCI) is a major cause of disability and morbidity throughout the world and Asia. The association between CSCI and voice difficulties is clinically well-recognized. So this study was meant to determine the impacts on voice following CSCI. The study aimed to determine the impacts on voice following Cervical Spinal Cord Injury (CSCI). Additionally includes finding out the proportion of voice difficulties among CSCI patients, to identify the number of functional, physical, and emotional impacts on voice after CSCI, and to determine the socio-demographic characteristics of the study population. This study was conducted by using a cross-sectional prospective survey method at the SCI unit of CRP. Participants were selected by using purposive sampling. The result states from the research that CSCI is more common in males than females and nearly half of the person has physical, emotional, and functional impacts on voice after CSCI. Among participants, the maximum participants 22.5% (18) rated their voice problem at a moderate level (VHI=11-20) after CSCI and 11.3% (9) participants faced voice problems at a very severe level, 13.8% (11) participants had severe level voice problem. The association between surgeries happened or not happened and the severity of voice problems among CSCI patients showed statistically non-significant. Patients with cervical spinal cord injury faces several clinical problems in our country, whereas nearly most of them experience mild to moderate voice deficits secondary to poor respiratory support. In Bangladesh, Speech & Language Therapy services for SCI patients are newly introduced in the last few years. So for providing proper comprehensive services to SCI patients the monitoring of communicative function from the acute phase to the community reintegration phase is essential

Energy Storage Solutions for Wind Generator Connected Distribution Systems in Rural Ontario

Environmental awareness and uncertainty about continued supply of fossil fuel has given rise to the renewable energy movement. Wind based power generation has been at the forefront of the motion to integrate distributed energy sources in the traditional power system. Due to various technical restrictions, wide scale penetration of wind generated power has been held back by most utilities. One such restriction is the variability of generation due to the technology’s dependence on Mother Nature. Energy storage devices can complement the wind generators by reducing this variability. These devices can store excess generation for supply during low generation periods. There are several promising technologies for both energy storage and power storage applications. Power storage devices provide short term fluctuation dampening capability while energy storage devices allow longer term storage. Pumped hydro, Vanadium Redox battery and Sodium-Sulphur battery are some of the viable energy storage technologies. This project provides a set of algorithms and guidelines to obtain the optimal configuration parameters of an energy storage device. To verify the efficiency of the algorithms, a model system has been obtained from a local utility. This system represents a typical radial distribution system in rural Ontario. The load demand, wind speed and energy prices for a period of one year have been obtained from utilities and Environment Canada. The main goal in determining the location of the storage device within a distribution system is to minimize the total cost of energy and the total energy loss during the period of analysis. Locating the storage device near the wind turbines or near the largest loads lead to the optimum results. Buses that are located near those elements can be considered as suitable locations for the storage device. The energy storage capacity and charge-discharge rate of the storage device are selected based on four criteria: maximize wind turbines’ load following capability, maximize capacity factors of the wind turbines, minimize system energy losses and minimize system energy costs. A weight based multi-objective optimization algorithm has been proposed to assign various priorities to these criteria and obtain a single solution. The larger the energy storage capacity of the storage device, the better the improvement in system performance. Lower charge-discharge ramp rates provide superior results. The parameters for storage device operating schedule, i.e. charge-discharge trigger levels, have been selected using similar criteria and weighted objective approach as for the capacity selection process. Higher charge trigger levels and moderate discharge trigger levels provide the optimum system performance. Once a set of parameters for the storage device has been selected, bus voltages over the period of study are analyzed. Voltage variations outside certain limits have been identified. Finally, a Monte Carlo based simulation approach is presented to obtain output parameter (system performance) variation ranges for pseudo random changes in input parameters

Collapsible Tabular Visualization of Aspects in Object Oriented Programming

Due to its implicit invocation nature ofAspect Oriented Programming (AOP), locating a jointpoint for executing aspect is extremely difficult. Hence,it becomes difficult to understand the application’sflow and behavior. Current AOP visualization tools havelimitations such as high dependency on other tools,confusing and excessive use of color to represent aspectsand using an outdated version of AspectJ. In thispaper, we propose a new approach collapsibletabular visualization tool to visualize and represent AOPfeatures to aid the programmers in betterunderstanding AOP applications. We have come outof traditional color-based aspect visualization and developeda web based tool: AspectViz that visualizes the aspects ina simple collapsible table. A questionnaire containingfour different questions related to aspects visualizationwas developed to compare AspectViz with currentvisualization tools. 20 graduate students andprofessional software developers were invited to participatein the test experiment as well as the survey. We havecompared its performance with existing AOPvisualization tools i.e. the AJDT and the AspectMaps andshowed how it outperformed in many cases, which is nocolor confusion, simple tabular visualization of aspects, nodependency on third-party software, easy to understand andthe time it took to find a particular aspect was less etc.Collapsible tabular visualization enhanced the usability andperformance of aspect locating in aspect-orientedprogramming

Combined Effects of Nutrient Management on Nutrient Content and Uptake of Transplant Aus Rice (BRRI Dhan48)

A field experiment was conducted at Sutiakhali, Mymensingh for crop production and chemical analysis was performed at Department of soil science, Bangladesh Agricultural University, Mymensingh to see the combined effect of nutrient management on nutrient content and uptake of Transplant  Aus  rice (BRRI dhan48) during march to july 2015 following Randomized Complete Block Design with four replications. The treatments were T1: RD (N75 P12 K45 S9), T2: STB (N74 P11 K36 S7), T3: INM (N54 P5 K27 S5+ CD @ 5.0 t ha−1), T4: Farmer’s practice (N69 P30 K37), and T5: Control (no fertilizer). The NPKS content and uptake by BRRI dhan48 were also influenced significantly due to combined use of manure and fertilizers. The maximum N, P, K and S uptake by grain (35.55, 6.99, 15.20 and 3.38 kg/ha respectively) were obtained from the application of Integrated Nutrient Management. The minimum N, P, K and S uptake by grain (20.08, 3.64, 8.35 and 1.74 kg/ha respectively) were found from T5: Control. Similarly, The maximum N, P, K and S uptake by straw (3.38, 5.43, 99.25 and 7.37 kg/ha respectively) were found from T3: INM. The minimum N, P, K and S uptake by straw (1.74, 2.67, 49.70 and 3.87 kg/ha respectively) were obtained from T5 (Control). The performance of the treatment T3 was better than T1, T2, T4 and T5 in nutrient content and uptake of BRRI dhan48. Considering nutrient content and uptake, the application of chemical fertilizers in combination with manure based on INM could be recommended for BRRI dhan48 production in aus season

Informal Sector Employment and Economic Growth: Evidence from Developing Countries in SDG Perspective

The understanding of the role of informal employment in economic growth is important to facilitate developing countries in safeguarding the decent work, productive employment, and inclusive growth agenda mentioned in Sustainable Development Goals (SDG) 8. The present study attempts to this end by investigating the role of informal employment on economic growth with an aim to assist in fulfilling target 8.3 of SDG. This study utilizes the data available for 20 developing countries for the period 2011–2019. Panel data analysis techniques have been applied, considering the percentage of total employment in the informal sector as the main explanatory variable of the models. The relevant macroeconomic indicators are included in the model as control variables. Empirical findings from Fully Modified Ordinary Least Squares (FMOLS), Dynamic Ordinary Least Squares (DOLS), and Dynamic Fixed Effect (DFE) models indicate a positive effect of informal employment on the economic growth of developing countries. The other macroeconomic indicators, per capita income, national expenditure, money supply, and economic freedom, are also found to contribute to the economic growth of the selected countries. This study reveals an important bidirectional causal association between informal employment and economic growth, a unidirectional causal link from per capita income to informal employment and from informal employment to national expenditure. Taking into account the contribution of the informal sector to the economy, this study fosters the need for achieving the targets mentioned in SDG 8 by adopting appropriate policies rather than punishing this sector immediately

The effect of the informal sector on sustainable development: Evidence from developing countries

This study aims to explore the impact of the informal sector on the sustainability of development. A large panel data set of 50 developing countries that spans over 2010–2019 has been utilized to this end while the informal sector is evaluated in terms of working poverty. Selecting indicators from three dimensions of sustainability, that is, economy, society, and environment, this study has constructed three indices and combines those to construct a symptomatic composite index of sustainability. Both the short run and long run panel data models have been applied to empirically investigate the impact of informal economic activities on the sustainability of development. Economic growth, national expenditure, and economic freedom of countries are used as control variables in the models and the estimated outcomes are found to be robust in empirical investigations. The outcomes of the study imply that the informal sector plays a detrimental role in the sustainable development of developing countries while economic growth and economic freedom contribute positively. Therefore, the prescribed strategy is to reduce informality from business and other economic activities that limit the scope of the economies and to understand the domain through which interventions can be made to move to a more formal economy. Integration of informal business and SMEs into the formal sector and firm-level awareness building in Corporate Social Responsibility can also be suggested to find a path towards sustainable development in addition to increased economic growth and enhanced economic opportunities of the developing countries

Incidence of anti-HBc antibody (IgG and IgM) among HBsAg negative apparently healthy blood donors

In person who is unable to produce HBsAg, anti-HBc antibody is a helpful marker of hepatitis B virus (HBV) infection. In the present study, we have tried to find out the incidence of anti-HBc (IgG and IgM) among blood donors HBsAg negative. People came for donating blood voluntarily or for their relatives (n = 1000) was selected on inclusion and exclusion criteria. Purposefully selected and collated samples were first tested by HBsAg ELISA of third generation reagent. HBsAg negative sample was tested with anti-HBc ELISA. Positive found in the first test was retested. Out of 1,000 samples on duplicate test, 117 positives were detected. The incidence of anti-HBc antibody among apparently healthy blood donors was found 11.7%