Control of euglenophyte bloom and fish production enhancement using duckweed and lime

Euglenophyte bloom is a common problem in most of the aquaculture ponds in Bangladesh. In the present study we conducted an experiment to control euglenophyte bloom for achieving better fish production using duckweed (Lemna minor) and lime. The experiment was carried out using four treatments, i.e., ponds were supplied with duckweed (T1), lime treatment (T2), both duckweed and lime (T3) and without supply of duckweed and lime (T4). Rohu, catla, mrigal, silver carp and silver barb were stocked and their gut contents were analyzed monthly. The ranges of water quality parameters were analyzed within the productive limit during the experimental period. The mean abundance of euglenophyte was significantly highest in T4 (17.62 ± 1.97 x 10^4 cells/L), followed by T2 (2.96 ± 0.20 x 10^4 cells/L), T1 (1.94 ± 0.35 x 10^4 cells/L) and T3 (1.53 ± 0.42 x 10^4 cells/L). Gut content analysis revealed that considerable amounts of euglenophyte were consumed by silver carp and silver barb, but not preferred by rohu, catla and mrigal. The gross yields of fish were 2133.37, 1967.76, 2816.52 and 1725.62 kg/ha/5 months in T1, T2, T3 and T4 respectively. The highest fish production in T3 and lowest fish production in T4 indicated the use of duckweed and lime is economically sustainable for controlling euglenophytes bloom, maintaining water quality and getting higher fish production

Capacitance-Voltage Characteristics of Nanowire Trigate MOSFET Considering Wave Function Penetration

Short channel  effects on the gate capacitance of nanowire trigate MOS field-effect transistors are studied considering wave function penetration. Capacitance-Voltage (C‑V) measurements are commonly used in studying gate-oxide quality in detail.  C‑V test results offer a wealth of device and process information, including bulk and interface charges. Capacitance indicates switching speed of the MOSFET. It is our goal to minimize capacitance as possible as we can in MOSFET. Due to our necessary to compact the Integrated Circuit as possible as we can for getting small electronics devices. Capacitance determines the speed of the IC. Every engineer in this section should know capacitance of his implementing device MOSFET to get exact result from this device. Whenever we deal with 10X10 nm scale or less device of MOSFET. We must concern the effect of wave function penetration into device in this stage classical mechanics fails to describe exact result of the system because electron can move in only one direction (x), in 3 Dimension, it cannot move in other two direction (y, z). i.e. confined in two direction which is not predictable by classical mechanics here quantum mechanics (QM) gives better solution of this problem. Therefore we consider QM in our study. Here we presented how wave function play vital role considering small area of trigate MOSFET. It is the analytical approach of QM and highly recommendation to use QM rather than CM to get accuracy. This result will be helpful for determining capacitance of trigate MOSFET.DOI:http://dx.doi.org/10.11591/ijece.v2i6.178

Poverty and Inequality in Seasonal Floodplain Areas of Bangladesh: The Role of Fish Income from Community Based Aquaculture

Over half of Bangladesh comprises of floodplains and most of the surrounding households depend on these floodplains for their livelihood. However, these floodplains remain unused during the monsoon season due to the lack of proper management systems. The WorldFish Center implemented an action research project through a Community Based Fish Culture (CBFC) system to assess the contribution of collective actions to aquaculture for sustainable use of floodplain resources and equitable distribution of benefits among the fisher communities. Using three years of panel data from the project as well as control sites, this study examines the impact of the Community Based Fish Culture system on income, employment, inequality and poverty. Both non-parametric (propensity score matching method) and parametric (random effect model) methods are used for impact assessment. Gini decomposition & FGT poverty method is used to estimate the effect of the CBFC system on fish income as well as total income inequality and poverty measurement respectively. Both (non-parametric and parametric) methods show that the CBFC system can significantly increase fish income without any negative impact on non-fish income and it also has a positive and significant impact on employment generation. Results reveal that fish income distributed equally after adopting this management system also has a positive impact on total household income distribution in the study area. Poverty analysis shows that the incidence (head count ratio) and depth (gap) of poverty are unambiguously lower for CBFC participant households rather than non-participants. Policy implications for sustainable management are discussed.Keywords: Fish and Aquaculture Sectors' Development, Fisheries Economics, Managing Development of Fisheries and Aquaculture sectors Part

The nature and impact of relative sea level rise on the coastal areas of Bangladesh: trend analysis and vulnerability assessment

Sea level rise is one of the most apparent and widespread consequences of climate change. Estimates of global past and future sea level changes have been the focus of many scientific studies throughout the last decades as the number of global coastal population is quite high and among them the low lying deltaic populations are especially exposed to the hazard of sea level rise. Bangladesh is a small deltaic country of South Asia which is about 12 times less than the size of Queensland. Extending from the Himalayan foothills in the north to the Bay of Bengal in the south, most of the country has low-gradient flat topography, suffers from deltaic subsidence with reduced sedimentation due to upstream dams, therefore often cited as one of the most vulnerable countries to sea level rise. However, to date few studies have quantitatively examined the decadal changes of sea level and its response along the coast of Bangladesh. This study aims to fill this knowledge gap by answering three questions: what is the nature and rate of sea level rise around the Bay of Bengal coast of Bangladesh, how the relative sea level rise (RSLR) has physically affected the coastal areas of Bangladesh over the past two decades (1989-2015) and how the relative sea level rise influences the physical vulnerability of the area and how the vulnerability can be measured.<br> <br> The long-term sea level trend was calculated from the satellite altimetry and tide gauge data. The global Absolute Sea level (ASL) trend from the altimetry data indicates that over the period of <a target="_blank">1993-2015</a>, the ASL rose on average about 3.2 mm per year. During the same period, the trend of Bay of Bengal is also steadily rising with a rate about 3.69 mm/year, about 0.5 mm more than the global rate. The Relative Sea Level (RSL) changes are linked with global climatic events as well as local land conditions. Based on the tide gauge data, it is evident that the RSL rate increases toward the northern part of the Bay of Bengal. The rate ranges from almost zero at the southernmost part of the Bay of Bengal and the highest is found along the Bangladesh coast. The spatial variations are caused by local land movements. The highest subsidence rate of about - 4 mm/year is found in the deltaic coast and in contrast, the eastern hilly coast is uplifting at a rate of about +0.5 mm/year.<br> <br> The seasonal variations of sea level are remarkable along the Bangladesh coast where the difference between the highest and lowest seasonal sea levels is about 1.01 m, and it is the highest in the world. The highest sea level is found in the month of July-August and lowest in February. When the monthly sea level is compared with the sea level pressure, a distinct inverse relationship is clearly visible. The pressure is lowest in the months of June and July and highest in December and January and the corresponding sea levels show the opposite pattern. The small contribution of pressure on sea level changes indicates the influence of other hydrological factors like the huge monsoon freshwater discharge by the Himalayan Ganges, Brahmaputra and Meghna Rivers. The transient sea levels appear as spikes in the residual time series and mainly indicate cyclone induced storm surges.<br> <br> The coastal change detection is focused on the deltaic western and central coast, and hilly lower eastern coast. Satellite image analysis indicates that from 1989 to 2015, the erosion amount is about 103 square km in the western coast and 283 square km in the central coast. During the same period, the accretion amount is about 44 square km in the western coast and 403 square km in the central coast i.e. erosion predominates in the western coast and accretion in the central coast. When the sediment ages are overlaid on the erosion-accretion map it is evident that the accretion predominates in the younger central part of the delta and its magnitude gradually decreases towards the older western part. The older western part with age of about 4,000 to 1,800 years BP, is predominated by erosion. In the short-length coast of Cox's Bazar area, the spatial distribution of erosion is not continuous; rather it occurs in specific points while the adjacent areas are not affected much. The discontinuous erosion of this area seems to be related with monsoon induced longshore current. The erosion rate in the deltaic coast ranges from 2.72 to 16.73 m/year and in the eastern hilly Cox's Bazar coast it is about 0.11 to 24.23 m/year. Generally, the erosion rate is 2000 times more than the rate of relative sea level rise.<br> <br> Accretion is mainly observed along the deltaic coast especially in the central part due to Ganges-Brahmaputra-Meghna River sedimentation. However, several land reclaiming processes have influence on the accretion process especially around the central and upper eastern coast. Accretion is also observed far inland in the western part of the delta especially around the tidal rivers. This part of the coastal zone is the oldest, has lost connections with the main rivers, and receives little fluvial discharge and sedimentation. Tidal asymmetry induced sedimentation is mainly responsible for this type of hinterland accretion.<br> <br> The coastal vulnerability is quantitatively measured by the Coastal Vulnerability Index (CVI) method using four variables viz. rate of relative sea level changes, wave height, mean tidal range and lithology. The calculated CVI values along the coastline of Bangladesh range from 4 to 11. About 3 to 4% of the Bangladesh coast show very low to low vulnerability. About half of the coast (52%) is dominated by moderate vulnerability and about 17% of the coast show high vulnerability. The very high vulnerability areas cover about 24% of the total coastal area. The vulnerability analysis provides useful insights about the spatial variability of risk due to relative sea level rise along the coast of Bangladesh and can be used for prioritizing areas for mitigation and land use zonation

Ion-acoustic higher order non-linear structures in quantum dusty plasma

The prominent features of higher order nonlinear ion-acoustic waves involving quantum corrections in an unmagnetized quantum dusty plasma are revisited with the theoretical framework of Hossain et al. [1]. The fluid model is demonstrated here by its constituent inertial ions, Fermi electrons with quantum effect, and immovable dust grain with negative charge. We have used the ideology of Gardner equation. The well-known RPM method is employed to derive the equation. Indeed, the basic features of quantum dust ion-acoustic Gardner solitons (GSs) are pronounced here. GSs are shown to exist for the value of dust to ion ratio around 2/3 which is valid for space plasma [2], and are different from those of K-dV (Korteweg-de Vries) solitons, which do not exist for the value around 2/3. The implications of our results are suitable for cosmological and astrophysical environments