pO polarography, contrast enhanced color duplex sonography (CDS), [18F] fluoromisonidazole and [18F] fluorodeoxyglucose positron emission tomography: validated methods for the evaluation of therapy-relevant tumor oxygenation or only bricks in the puzzle of tumor hypoxia?

<p>Abstract</p> <p>Background</p> <p>The present study was conducted to analyze the value of ([¹⁸F] fluoromisonidazole (FMISO) and [¹⁸F]-2-fluoro-2'-deoxyglucose (FDG) PET as well as color pixel density (CPD) and tumor perfusion (TP) assessed by color duplex sonography (CDS) for determination of therapeutic relevant hypoxia. As a standard for measuring tissue oxygenation in human tumors, the invasive, computerized polarographic needle electrode system (pO₂histography) was used for comparing the different non invasive measurements.</p> <p>Methods</p> <p>Until now a total of 38 Patients with malignancies of the head and neck were examined. Tumor tissue pO₂was measured using a pO₂-histograph. The needle electrode was placed CT-controlled in the tumor without general or local anesthesia. To assess the biological and clinical relevance of oxygenation measurement, the relative frequency of pO₂readings, with values ≤ 2.5, ≤ 5.0 and ≤ 10.0 mmHg, as well as mean and median pO₂were stated. FMISO PET consisted of one static scan of the relevant region, performed 120 min after intravenous administration. FMISO tumor to muscle ratios (FMISO_T/M) and tumor to blood ratios (FMISO_T/B) were calculated. FDG PET of the lymph node metastases was performed 71 ± 17 min after intravenous administration. To visualize as many vessels as possible by CDS, a contrast enhancer (Levovist^®, Schering Corp., Germany) was administered. Color pixel density (CPD) was defined as the ratio of colored to grey pixels in a region of interest. From CDS signals two parameters were extracted: color hue – defining velocity (v) and color area – defining perfused area (A). Signal intensity as a measure of tissue perfusion (TP) was quantified as follows: TP = v_mean× A_mean.</p> <p>Results</p> <p>In order to investigate the degree of linear association, we calculated the Pearson correlation coefficient. Slight (|r| > 0.4) to moderate (|r| > 0.6) correlation was found between the parameters of pO₂polarography (pO₂readings with values ≤ 2.5, ≤ 5.0 and ≤ 10.0 mmHg, as well as median pO₂), CPD and FMISO_T/M. Only a slight correlation between TP and the fraction of pO₂values ≤ 10.0 mmHg, median and mean pO₂could be detected. After exclusion of four outliers the absolute values of the Pearson correlation coefficients increased clearly. There was no relevant association between mean or maximum FDG uptake and the different polarographic- as well as the CDS parameters.</p> <p>Conclusion</p> <p>CDS and FMISO PET represent different approaches for estimation of therapy relevant tumor hypoxia. Each of these approaches is methodologically limited, making evaluation of clinical potential in prospective studies necessary.</p

Water data andinformation system in Sri Lanka

Improving knowledge of a country's water resource is indispensable for the well being of its people and environment. Reliable information on the state and trends of water resources is a perquisite for sound decisions on the sustainable management of water resources. Probably since the beginning of human life on earth it would have been common knowledge that water is of great importance. Clusters of human habitats would have had water data and information systems built into their lives though there may not have been a necessity to document or structure them due to the abundance of the resource both in sufficient quantities and acceptable quality. However with the increasing growth and competition it has become a necessity for various management or administrative units to optimally manage the water available for such units. Accordingly water data and information systems have to be put in place so that the available resource could be understood and sustainable managed. Accurate and comprehensive water data are critical to engineers, planners and decision makers at all levels of government, researchers, developers, and the business community. Increasing demand for water, the associated need to rationally manage water, forecasting challenges which increase with the pressure of population growth and requirements of sustaining the environment, are demanding improvements in hydrologic analysis and predictions together with outputs with lesser uncertainties. This makes water data more important than in the past. Quantifiable spatial and temporal data and information on how much water is available in the country's river basins is required to provide a sound scientific basis to these assessments. Knowledge on the quality and distribution of the resource in space and time is also an important equirement. In Sri Lanka it had been identified that water data and information management is a key component in the sound assessment, planning and engineering of water resources and other water based activities and this is reflected in the report' which has highlighted areas where water data information activities within Government agencies could be improved. If the quest to acquire knowledge about water is to be successful then it is important to use data of correct temporal and spatial resolution and desired quality. Data resolution varies depending on whether the use is for water balance, flood assessment, rainfall predictions, urban drainage, detention and retention storage designs etc. Some sensitive data requires high accuracies while some data may not be demanding in terms of quality. As such it is important to note that appropriate water data and information are of extreme importance to carryout productive and contributory water assessments. On the other hand high resource demand makes it extremely expensive for a data and information system to capture, process and store all water and water related data at very fine spatial and temporal resolutions. This is due to the large requirement of staff and equipment for data capturing and the necessity of high speed, high capacity computers, servers, networks, associated equipment, capable staff and tools for processing etc., when handling large amounts of data. As such there should be research on data capture, storage, analysis and retrievals to make sure that optimal resources are used 207 180 for data and information management. Therefore research on how water data and information are to be captured. stored. analyzed and retrieved is of prime importance to ensure rational use and management of water resources

Mathematical modelling of the Gin Ganga watershed

Planning and Execution of development activities in watersheds require assessing possible development scenarios and estimating watershed behaviour under such situations. In this connection it is very important to understand the hydrological behaviour of a watershed to satisfy water resources concerns. Mathematical watershed models enable this testing of watershed development scenarios under different changing situations either in the temporal or in the spatial scale. As such this study as its primary objective includes the development of a conceptual mathematical model for the Gin Ganga Watershed (Figure 1). The modeling effort is based on a monthly time resolution. Monthly temporal scale is considered adequate to identify the seasonal response of watersheds in cases of inputs for groundwater models, irrigation reservoir operation planning, irrigation water requirement planning etc. The monthly watershed model developed in this study is a lumped conceptual model using a three-layer linear tank structure based on the Tank Model Concept (Sugawara 1960).Senate Research Gran

Irrigation infrastructure management requirements to ensure water security for impoverished rural populations under climate change scenario

Climate change studies have come to maturity with the 4th report of the Intergovernmental panel on Climate Change in 2007. Conclusions about temperature increases, rainfall variations, climate change relationships with evaporation etc., have more or less reached consensus. However climatologists have to fine tune climate models to refine the predictions. It is now necessary to assess the sustainability of the water and its surrounding environment with the anticipated climate changes. As at present in Sri Lanka there is minimum research attempting to link climate change impacts to infrastructure development, and there is none in the area of irrigation. Therefore it is necessary for countries like Sri Lanka where majority of the population depends on irrigated agriculture utilising a large number of small reservoirs, to ascertain the effect on its irrigation systems and identify the adaptation measures that should be implemented. A significant increase of water for irrigation sector would mean pressure on others which compete for water. If water is inadequate for irrigation then it would certainly lead to socio economic issues commencing from the farming community. In order to address these issues and to identify suitable adaptation options, the present research carried out spatially distributed irrigation water demand modelling to assess the administrative district wise requirements in the year 2025. Reservoir water balance modelling was carried out for four selected districts to study the adequacy of minor irrigation reservoirs. Present work describes the modelling efforts that incorporated system deterioration due to lack of maintenance superimposed on the climate changes. The study used irrigation department guidelines, published data and made rational assumptions to quantify the impacts on the irrigation systems. It was revealed that it is necessary for water and related infrastructure managers and engineers to incorporate suitable maintenance programs, and make significant efforts to improve the project efficiencies as climate change adaptation measures

Field measurement of infiltration for irrigation & drainage

An understanding of the infiltration of water into soil is very important for irrigation engineers, to ensure optimum use of water resources. Infiltration into the soil under unsaturated and saturated conditions are often discussed in the modeling of water resources systems. Similarly drainage of water under varying conditions of saturation reflecting drainage from irrigation, drainage during floods arresting threats of salinity are also challenge faced by many practicing engineers. These have resulted great concerns in the estimation of infiltration parameters. The determination of infiltration parameters are based on either laboratory experiments or on insitu testing. Due to the most likely non-representativeness of laboratory samples, irrigation engineers often prefer insitu testing to estimate infiltration parameters. There are various insitu methods or field methods used for the measurement of infiltration. This research was conducted to study the field methods used to estimate infiltratio

Extraction of parameters and modelling soil erosion using gis in a grid environment

Soil erosion assessment for watershed management is one of the major concerns because in reality it is not possible to conserve all areas under the threat of erosion because of the financial constraints. Geographic Information Systems are becoming a popular tool when seeking solutions to issues of these kinds, which are spread over large spatial extents. However it is of utmost importance to ensure a reason~ble assessment of soil erosion because this is the core to any such decision making. Use of USLE for erosion assessment using GIS poses concerns since some parameters are polygon specific. This could be overcome easily by the use of grid-based data layers and selecting appropriate size of grids for a particular data st!t. The most common problem is the computation of the slope length and slope class parameters of a particular grid of a DEM. The present study describes a different methodology to compute these factors using a digital elevation model of the study area. A watershed from Sri Lanka covering an area of 23,000ha was selected for modelling. Field survey results recognised the need to calibrate the model for planning purposes. Model calibration used a weighting scheme. A comparative analysis of results for the same project area from the grid-based model and a model that did not use grid-based data indicated an almost same value of mean annual erosion level for the watershed. This paper also carries a discussion of the key issues that need to be considered when modelling in different environments. Suitably developing a model in a grid data environment provides better flexibility to compute erosion levels for different spatial scales. Grid based method also enables the meaningful use of pixel based remotely sensed land cover information for modelling soil erosio

Present day needs in environmental impact assessment evaluation - the UKHP of Sri Lanka, an example of the challenge : B

Growing environmental concerns, which had arisen due to bitter experiences from the develapment projects of the past, now require public involvement to ensure that the best option is implemented. This includes an evaluation of the environmental impact assessment reports by" the environmental authorities prior to the grant of clearance to proceed. In Sri Lanka the environmental legislation was enacted in the year 1980 and · the present era could be considered as the transition from 'proponent' -driven development to 'proponent with public' driven development. Since the government is interested in achieving its development objectives without undue delays, it is necessary for the projects to obtain environmental clearance at the earliest. However it is often noted that there is a tendency to sideline the environmental aspects of projects citing the urgency of the government. The environmental authorities identify this as deficiencies in the EIAR. In the present day contest it is necessary for the EIA evaluators to extend more efforts than expected until the proponents. are matured enough to account for environmental concerns. The present work of Upper Kotmale Hydropower Project (UKHP) in Sri Lanka presents an evaluation of the key aspects of the EIAR and the efforts taken in the above direction

Estimation of hydropower potential of Kuru ganga at Bopathella

In Sri Lanka, the power generating system is predominantly based on hydropower which has provided approximately 90% of the total demand in the recent past. The government of Sri Lanka is encouraging not only the development of large hydropower schemes, but also mini and micro hydropower systems. Kuru Ganga mini hydropower project plans to exploit the head of 'Bopath Ella' waterfall which is located on Kuru Ganga, a tributary of the river Kalu Ganga. Gauged data at an adjacent catchment Deraniyagala on the river 'Seethawaka Ganga' were extrapolated to obtain streamflow at Bopath Ella, using rainfall, topography, land use and soil characteristics of the two watersheds. Missing streamflow data at the gauging station Deraniyagala was filled using a mathematical watershed model based on the Tank Model. Data extrapolated for Bopath Ella catchment was incorporated into a water balance model to compute the hydropower availability. The daily flow duration curve at Bopath Ella was used to estimate the appropriate downstream water releases. Based on this, a suitable level of water release for maintenance of the waterfall aesthetics and the riparian environment was established. A simple computer spreadsheet was developed considering water balance at the weir pond estimating river flow for power generation. River inflows, rate of evaporation, water releases for riparian area sustenance etc, were considered in the water balance computations. Extractable power from the estimated streamflow at Bopath Ella was computed assuming a turbine capacity of 10 cumecs