Sedimentary Characteristics and Nutrient Sequestration of Embanked Floodplains Along the Lower Mississippi River, Mississippi and Louisiana

The Mississippi River Basin is the largest river basin in North America and the third largest river basin in the world. Most of the corn, soybeans, wheat, cattle, and hogs harvested in the United States come from the Mississippi River Basin and about 58% of the entire drainage basin is croplands. Runoff from these lands carries sediments and nutrients, and the Mississippi River transports these downstream and ultimately deposits them in the Gulf of Mexico. The northern Gulf of Mexico is one of largest human-caused hypoxic zones in the world. Hypoxia is the phenomena where the dissolved oxygen level decreases in the water because of the eutrophication. Nutrients, particularly nitrogen (N) and phosphorus (P) are the main causes of eutrophication and the Mississippi River is the main source for nutrients in the Gulf of Mexico. The lower Mississippi River is frequently subjected to flooding during high discharge and floodwater sediments and nutrients are introduced into the floodplain. This study hypotheses that considerable concentration of nutrients are sequestrated in the Lower Mississippi Floodplain and the sequestration patterns are different in different sub-fluvial environments. Eight sediment cores recovered from three different sub-environments including levee backslope, point-bar and backswamp, taken from the Lower Mississippi floodplain were analyzed for their organic matter (OM), carbon (C), nitrogen (N), phosphorus (P), magnetic susceptibility, and particle size with depth. High concentrations of C, N, and OM are decreasing with depth and become low and relatively constant concentrations at depth no more than 25 cm. Levee backslope sediments consist of high silt and sand size particles, and have low concentration of C, N and OM. Backswamps and point-bar sediments are rich in clay size particles, C, N, and OM. C and N in the studied sediment samples were mainly originated from OM and total P is mainly from inorganic sources. Average concentration values in the topsoil for three sub-environments show moderate C and N concentrations and significantly high P concentrations compared to previous studies carried out in similar environments. Depth and OM concentration are the main factors governing the C and N concentrations while depth and clay fraction is more important in determining P concentrations. Results of this study show that floodplains are served as a sink for removing nutrients from further downstream movement effectively. Further study should be completed to understand the temporal changes in nutrient sequestration of the study area in order to quantify the amount of nutrients sequestrated within the floodplain

Control of a fractional-slot, concentrated-wound interior permanent magnet generator for direct-drive wind generation applications

This thesis assesses improvements to two types of control for a novel interior permanent magnet (PM) synchronous generator with fractional-slot, concentrated-wound stator designed for direct-drive wind energy conversion. The two control techniques assessed are a) field oriented control using a back-to-back converter arrangement and b) a current controller with a rectifier-connected boost converter. These were chosen to understand the potential and the limitations of the generator and its control. Modifications to the control techniques are proposed to improve the generator efficiency, the dynamic performance in the flux-weakening range and the torque ripple performance. The adequacy of the distributed-wound PM synchronous machine model for steady-state and dynamic control of this generator was experimentally validated under field oriented control using a back-to-back converter connected to the grid. The effectiveness of the existing current trajectory controls on the efficiency of the new generator was evaluated. A new flux-prioritized maximum torque per ampere technique which is independent of speed-dependent predefined trajectories was introduced, and a similar efficiency improvement was gained as the conventional loss minimization method in the partial load range. Thus, the control model validation and efficiency imrpovement of the new generator are the primary contributions. The dynamic performance of the generator, directly driven by a non-pitchable wind turbine emulator was investigated from cut-in speed to cut-out speed using maximum power point tracking and then constant power control above rated speed. A significant contribution was done in the power control above base wind speed that was achieved by utilizing the extended flux-weakening capability of the machine with its wide constant power-speed range. High torque ripple was observed when operated with a rectifier and boost converter using boost converter inductor current control. A new direct torque control technique using a machine rotor position based torque estimator was proposed to minimize this torque ripple. Eventhough the reduced torque ripple is still higher than that with back-to-back converter, the achieved ripple reduction is significant. The control of generator speed under each method is also demonstrated. Although the new method gives a faster speed dynamics than the conventional method, it shows slower speed response than that of back-to-back converter control. However, the significance of the study using a diode rectifier-connected boost converter control is highlighted with the achieved torque ripple minimization and performance enhancement of the generator. This study is expected to open new investigations in flux-weakening control of the PM generators using rectifier-connected boost converter. In this thesis, back to back converter control is demonstrated in order to optimally control the novel generator under the field oriented control, energy efficient current control and power control together with voltage control operating above rated speed. Torque ripple minimization of the generator is also presented when used with a diode rectifier-connected boost converter control

Species Composition and Visiting Frequencies of Flower Visitors of Chromolaena odorata

Plant-animal interaction has been a major theme in ecology as it has helped ecologists to rule out different patterns they observed in the surrounding environments. Chromolaena odorata is another plant species that is studied extensively as it has become a major troublesome weed in many parts of the tropics. But, handful of studies are available on pollination of this invasive plant species in dry forests and its function as a pollinator sink in these environments. The current study was carried out in a dry zone secondary forest patch in North-Central Sri Lanka to assess the diversity, abundance, and pollination strength of flower visitors associated with the C. odorata. The results suggest that the diversity of Hymenoptera and Lepidoptera is higher than the other insect orders that visited C. odorata, but all species exerted equal pollination strength on the plant. The attraction of large numbers of insects is concluded to as one of the factors that contribute to the reproductive success of C. odorata in dry zone forests

The relative importance of olfactory signaling to fly-moss spore dispersal network structure of two sympatric moss species in Newfoundland, Canada

In Newfoundland, Splachnum ampullaceum (herbivore dung scent mimic) and S. pensylvanicum (omnivore dung scent mimic) grow in bogs on summer moose (Alces alces L.) dung and via olfactory and visual deception have their spores dispersed to dung by flies. In Chapter 2, the addition of carnivore and herbivore-mimicking scent increased the number of visiting flies, and the addition of carnivore scent attracted carrion flies, and this effect was greatest for S. pensylvanicum. In Chapter three consecutive years of fly trapping data for both species of moss were compared using Network analyses. Results showed that both mosses attract a generalized fly fauna (lower network specialization (H₂average) 0.171), most of which are also associated with summer moose dung (average connectance low 0.799). Also, the fly faunas of S. ampullaceum and S. pensylvanicum did not differ from each other in all three years

An Economic Analysis based on Equivalent Variance of the Fertilizer Subsidy: A Case of Mahaweli System H in Sri Lanka

AbstractThe theory of equivalent variance postulates that, cash transfers are preferred over material subsidies as overall production is expected to increase if the government grants a cash transfer equivalent to the value of the material subsidy. In line with this theoretical argument, the government of Sri Lanka recently undertook a major change in the agriculture subsidy policy by converting the material fertilizer subsidy in to a cash transfer. However this policy reform has received many criticisms from several parties, including the farmers and farmer representatives. The study aims at analysing the economic impact of this policy change on the paddy output by employing macro and micro perspectives. The analysis is based on time series data from 1961 to 2013 at national level and survey data on the Yala seasons of 2015 and 2016 at micro level. The survey was conducted using cluster sampling method and Meegalewa Grama Niladhari division in Mahaweli System H was selected for this purpose. The findings of this study indicate that fertilizer is a significant determinant of the paddy output in Sri Lanka. Further, it was revealed that the government has not allocated a cash transfer equivalent to the material fertilizer subsidy provided under the former subsidy scheme. Thus, a significant reduction can be expected in the paddy output in the Yala 2016. The study recommends that the government should grant equivalent cash transfer or encourage organic fertilizer usage in order to reap the benefits of this policy change.Keywords: Paddy Cultivation, Fertilizer Subsidy, Cash Transfer, Equivalent Varianc

Short term effects on liver and renal functions following chemotherapy treatment for breast cancer patients in oncology clinic, university hospital Kotelawala Defence University in Sri Lanka

Background: Breast cancer tops the global cancer incidence rates, having the highest rate of death among women. The primary objective of this study was to assess the impact of standard chemotherapy treatment dose adjusted for the Sri Lankan population, on hepatic and kidney function of breast cancer patients. Methods: The study conducted a cross-sectional, retrospective and prospective analysis of 75 breast cancer patients who received doxorubicin, cyclophosphamide, and paclitaxel chemotherapy regimen with normal liver and renal function at baseline at UHKDU oncology clinic. The study population had a mean age and BMI of 54.04±11.33 years and 26.7±3.89, respectively. Prior to starting the 16-cycle chemotherapy treatment, mean serum SGOT, SGPT, Creatinine, and eGFR values were 27.57 U/l, 31.32 U/l, 0.71 mg/dl, and 99.07 ml/minute/1.73 m2 respectively. Results: During the treatment, there was a statistically significant increase in the mean values of SGOT and SGPT (p<0.05), whereas there was no significant variation in the mean values of creatinine and eGFR (p>0.05) compared to the baseline results. The study identified a significant positive correlation in SGOT (r=0.793) and SGPT (r=0.872) values, while there was a noteworthy negative correlation (r=-0.757) between eGFR and chemotherapy cycle. Furthermore, there was a positive significant correlation between serum creatinine levels and chemotherapy cycle (r=0.579). Conclusions: The dosed adjusted chemotherapy regimen had a significant impact on hepatic function but had no statistically significant impact on renal function among the study population. Further research is recommended to evaluate the long-term effects of standard chemotherapy treatment on liver and kidney functions

IMPACT OF MACROECONOMIC VARIABLES ON STOCK MARKET PERFORMANCES: EVIDENCE FROM SRI LANKA

After eradicating 30 years of war, Sri Lanka has been rising like a phoenix bird rises from the ashes of its predecessor. With the golden opportunity to experience an impressive development within almost all the sectors inside the country, Colombo stock exchange (CSE) was labeled as the world’s best performing stock exchange according to Bloomberg in 2010. Unfortunately, it did not last longer. According to an analysis of Bespoke investment group in 2012, Colombo stock exchange became the second worst performing stock exchange ahead of Dhaka exchange in Bangladesh.The aim of this paper is to measure the impact of macroeconomic variables on the all share price index (ASPI) of CSE in Sri Lanka. Monthly data collected from publication of Central Bank of Sri Lanka from 2006 to 2016 were employed. In the model specification, two dummy variables were included to test the impact from civil war prevailed in the country and global financial crisis on share prices and the parameters were estimated using Ordinary Least Square (OLS) method. The results indicate that macroeconomic variables have an overall impact towards ASPI of Sri Lanka. Interest rate, industrial production index and civil war affected negatively on ASPI while US Dollar exchange rate and real GDP growth rate reacted positively on the all share price index. Importantly, global financial crisis positively affected the all share price index in Sri Lanka, which is contradictory to the experiences of developed countries. Study concluded that even though there is an uncertainty prevailing within external world, there is a tendency of attracting foreign investment towards capital market when a country is having a positive condition like Sri Lanka ending thirty years of war. Further, it reveals that inflation rate and money supply growth rate does not have a significant impact on the share price index of Sri Lanka. These findings can be significantly incorporated in government policy making which will be aimed at creating a strong capital market, investment decisions of local and foreign investor, stock market regulating authorities and financial analysts who develop forecasting models with reference to share price indexes.Keywords: Macroeconomic Impact, Colombo Stock Exchange, All share price index, Ordinary Least Square Method, Sri Lank