Impact of climate change and land use on groundwater salinization in southern Bangladesh-implications for other Asian deltas

Pervasive salinity in soil and water is affecting agricultural yield and the health of millions of delta dwellers in Asia. This is also being exacerbated by climate change through increases in sea level and tropical storm surges. One consequence of this has been a widespread introduction of salt water shrimp farming. Here, we show, using field data and modeling, how changes in climate and land use are likely to result in increased salinization of shallow groundwater in SE Asian mega-deltas. We also explore possible adaptation options. We find that possible future increase of episodic inundation events, combined with salt water shrimp farming, will cause rapid salinization of groundwater in the region making it less suitable for drinking water and irrigation. However, modified land use and water management practices can mitigate the impacts on groundwater, as well as the overlying soil, from future salinization. The study therefore provides guidance for adaptation planning to reduce future salinization in Asian deltas

Investigation of the Magnetic Response of a Nanocrystalline High-Frequency Magnetic Link With Multi-Input Excitations

© 2019 IEEE. With the technological advancement of magnetic materials and semiconductor devices, the use of high-frequency magnetic link made of high-saturation induction and low specific core loss nanocrystalline alloy has been gaining popularity to replace the common dc link or ac link specially in integrating multiple renewable sources to the grid. The magnetic integration of multiple renewable sources through a common magnetic link has a number of advantages including galvanic isolation compared with the common dc or ac link. However, the magnetic response of the common magnetic link under multi-input excitations highly affects the energy conversion efficiency. To the best of the authors' knowledge, the magnetic response of an advanced magnetic-material-based magnetic link under multi-input excitations has not been well investigated in the literature. In this paper, a systematic investigation is carried out to interconnect multiple sources through a common magnetic link. The magnetic response and the procedure used in the investigation are also presented and discussed in this paper

A Critical Review of Concepts, Benefits, and Pitfalls of Blockchain Technology Using Concept Map

Blockchain is relatively a new area of research. However, a surge of research studies on the blockchain has taken place in recent years. These research studies have mostly focused on designing and developing conceptual frameworks to build more reliable, transparent and efficient digital systems. While blockchain brings a wide variety of benefits, it also imposes certain challenges. Therefore, the objective of this research is to understand the properties of blockchain, its current uses, observed benefits and pitfalls to provide a balanced understanding of blockchain. A systematic literature review approach was adopted in this paper in order to attain the objective. A total of 51 articles were selected and reviewed. As outcomes, this research provides a summary of the state-of-the-art research studies conducted in the area of blockchain. Furthermore, we develop a set of concept maps aiming to provide in-depth knowledge on blockchain technology for its efficient and effective usage in the development of future technological solutions

An inclusive city water account by integrating multiple data sources for South-East Queensland (SEQ), Australia

Cities are the hotspots of impacts on local and distant water resources through economic activity and consumption. More than half of the world's population lives in cities, which is expected to reach around two-thirds by 2050. Such a high level of increased urbanization calls for higher attention towards inclusive, safe, resilient, and sustainable cities (Sustainable Development Goals 11). To evaluate sustainability, inclusiveness, and resiliency pathways, a variety of sustainability indicators have been proposed, including the water footprint. The water footprint is defined as the total volume of freshwater used for the goods and services consumed. It covers both direct (e.g. drinking and cleaning) and virtual water flows (water used in the goods and services supply chain, hence also known as embedded water). Virtual water flows through products and services produced in other locations using their water resources influence the function, prosperity, and growth of the cities. Yet, this aspect is absent in the sustainability and strategic city water footprint reduction goals of Australian cities. To fully account for the water dependencies of Australian cities, direct and virtual water flows need to be known. To this purpose, we build inclusive city water of South-East Queensland (SEQ) by combining material flow analysis (MFA) and the multiregional input-output (MRIO) model. Water consumption in SEQ is used to quantify the water footprint on local water resources and net blue virtual water import. Together, this constitutes the water footprint on national water resources. Our results show that the water footprint of SEQ on local water resources is 620 GL with a net virtual water import of 1382 GL. Therefore, the water footprint of SEQ on national water resources is 2002 GL. The water footprint of SEQ on local water resources consists of direct water consumption by households (192 GL) and the industrial sector (428 GL). The consumed direct water of the SEQ industrial sector flows as virtual water to SEQ (149 GL), the rest of Australia (RoAUS) (all other regions except SEQ) (211 GL), and the rest of the world (68 GL). The virtual water inflows breakdown by source regions showed that 386 GL, 1019 GL, and 256 GL of virtual water imported from the major cities (Sydney, Melbourne, Adelaide, and Perth); regional areas of NSW, Victoria, and QLD; and RoAUS, respectively. Overall, the proposed inclusive city water account can enhance subnational estimates of city water footprint for benchmarking, as well as inclusive and resilient city water planning

A Modified Carrier-Based Advanced Modulation Technique for Improved Switching Performance of Magnetic-Linked Medium-Voltage Converters

© 1972-2012 IEEE. The high-frequency magnetic link is gaining popularity due to its lightweight, small volume, and inherent voltage balancing capability. Those features can simplify the utilization of a multilevel converter (MLC) for the integration of renewable energy sources to the grid with compact size and exert economic feasibility. The modulation and control of the MLC are crucial issues, especially for grid-connected applications. To support the grid, the converter may need to operate in an overmodulation (OVM) region for short periods depending upon the loading conditions. This OVM operation of the converter causes increased harmonic losses and adverse effects on the overall system efficiency. On top of that, the size and cost of filtering circuitry become critical to eliminate the unwanted harmonics. In this regard, a modified OVM scheme with phase-disposed carriers for a grid-connected high-frequency magnetic-link-based cascaded H-bridge (CHB) MLC is proposed for the suppression of harmonics and the reduction of converter loss. Furthermore, with the proposed OVM technique, the voltage gain with the modulation index can be increased up to the range which is unlikely to be achieved using the classical ones. Extensive simulations are carried out with a 2.24 MVA permanent magnet synchronous generator based wind energy conversion system, which is connected to the 11 kV ac grid through a high-frequency magnetic-link and a five-level CHB MLC. A scaled down laboratory prototype is implemented to validate the performance of the converter

Pattern of Childhood Malignant Tumour in the Paediatric Surgery Department of Bangabandhu Sheikh Mujib Medical University

Background: Childhood malignancy is fast becoming an important paediatric problem in Bangladesh. They differ markedly from adult malignancy in their nature and distribution. This is a 5 years retrospective study of childhood malignant tumour as seen at the paediatric surgery department of Bangabandhu Sheikh Mujib Medical University (BSMMU). Objectives: The objective of this study is to determine the types of malignant patients admitted in the paediatric surgery department of BSMMU and also to know their age and sex distribution. Methods: This is a 5 years retrospective study from January 2005 to December 2009 in the paediatric surgery department of BSMMU, Dhaka, Bangladesh. All admitted malignant patients, aged up to 15 years diagnosed by means of histological or cytological examination included in this study. Results: Seventy (70) malignant patients were admitted during the study period, 65.7% patients were male and 34.3% patients were female with a male female ratio of 1.9:1. Fifty two (74.3%) patients were below 5 years and eighteen (25.7%) patients were between 5 to 15 years. The Wilms’ tumour was the most common malignant tumour which accounted for 42.8%. Hepatoblastoma was the second most common (24.2%). The other malignant tumours were neuroblastoma (15.7%), Non-Hodgkins lymphoma (5.7%), Rhabdomyosarcoma (4.2%), malignant fibrous histocytoma (1.4%), Fibroscarcoma (1.4%), Osteosarcoma (1.4%), malignant sacrococcygeal teratoma (1.4%), carcinoma of the rectum (1.4%0. Conclusion: Based on the result of this study, Wilms’ tumour is the commonest paediatric solid malignancy in our country. Carcinoma of the rectum may rarely occur in paediatric age group. Key words: Frequency; malignant solid tumor; children. DOI: http://dx.doi.org/10.3329/bsmmuj.v4i2.8638 BSMMU J 2011; 4(2):99-10

Post-operative sonological evaluation of pelvi-ureteric drainage of unilateral A-H pyeloplasty in children

Background: Pelvi-ureteric junction obstruction is the most common cause of pediatric hydronephrosis where A-H pyeloplasty with D-J stent is the established treatment option with a high success rate. We observed the predictive value of sonological parameters for early detection of postoperative obstruction at the new pelvi-ureteric junction in children following unilateral A-H pyeloplasty. Methods: This cross-sectional study included 12 children who underwent unilateral A-H pyeloplasty. Post-operative follow-up was done after D-J stent removal and completed within six months. Maximum antero-posterior pelvic diameter (APPD), cortical thickness (CT), and pelvi-cortical (P/C) ratio were compared. Results: Mean APPD was 32.7 mm at the day after removal of the stent, 24.4 mm at one month, and 19.7 mm at four months. Mean CT was 5.2 mm at the day after removal of the stent, 6.1 mm at one month and 8.0 mm at four months. P/C ratio was 8.3 mm at the day after removal of the stent, 5.2 mm at one month, and 3.4 mm at four months. Increased CT and reduced P/C ratio were significant at four months (P= 0.05). Conclusion: CT value and P/C ratio can be used as an early marker of success for pelvi-ureteric drainage following A-H pyeloplasty.

Analysis of Early Outcome of Surgery in Spontaneous Primary Intracerebral Haemorrahage in Relation to Preoperative Glasgow Coma Scale

Objectives : To correlate preoperative Glasgow coma scale with early outcome of surgery. Methods: This prospective study was done at the department of neurosurgery of Dhaka Medical College (from January 2009 to June 2010) on consecutively selected patients with a suspicion of intracerebral haemorrhage and subsequently confirmed by CT scan of brain. A total of 30 hypertensive patients with their age ranged from 41 to 80 years with Glasgow coma scale 6 to 12 were included in this study. Co-morbid patients like cardiac, respiratory and renal failure requiring artificial maintenance of blood pressure and respiration were excluded in this study. All these patients were evaluated on the basis of detailed history from attendants (as patients were stuporous and semicomatose), clinical examination and subsequently CT scan of brain (at presentation and at 7th postoperative day). All these patients were operated and followed up during hospital stay and at 30-day after operation, by observing Glasgow coma scale and Glasgow outcome scale. Results: 20 patients had Glasgow coma scale 6 to 8 on admission, among them Glasgow outcome scale was 5 in 4(20.0%) patients, was 3 in 4(20.0%) patients and was 1 in 12(60.0%) patients. 10 patients had Glasgow coma scale 9 to 12 on admission, among them Glasgow outcome scale was 5 in 6 (60.0%) patients, was 4 in 1(10.0%) patient and was 3 in 3(30.0%) patients. Conclusion: Surgery in relation to preoperative Glasgow coma scale (Glasgow coma scale) had a significant correlation with early outcome of surgery. From the current study removal of haematoma when Glasgow coma scale >8 lower the morbidity and mortality, which was statistically significant DOI: http://dx.doi.org/10.3329/bsmmuj.v4i2.8633 BSMMU J 2011; 4(2):70-7