ABSTRACT:

Inter-population disparities in a species have been shown to occur as an adaptation to different thermal regimes in the environment. We investigated the thermal sensitivities of the tropical toad Duttaphrynus melanostictus (Asia Common Toad) from two populations at different altitudes: Nuwara-Eliya – 1870 m, and Polonnaruwa – 25 m, above mean sea level. The two locations were separated by what may be considered a short direct distance – 110 km. Thermal sensitivity trials were conducted at six temperatures between 12 and 39 °C. Assessments were made using the performance indicators jump distance, jump force, contact time on the test plate following stimulus to jump, and righting time after being overturned. Optimum performance is taken to be the greatest jump distance and jump force, the least contact time on the test plate, and the least righting time. The populations at the two altitudes had markedly different thermal sensitivities – toads in the cool area (Nuwara-Eliya) performed at an optimal level under low temperatures, whereas the toads in the warm area (Polonnaruwa) performed optimally under high temperatures. The finding that the thermal optima (i.e., the temperatures at which the optimal performance for the four performance indicators was recorded) of the toads in Polonnaruwa were below the mean maximum ambient temperature at this location suggests that these toads would be more susceptible to global warming than those in Nuwara-Eliya whose thermal optima were above the mean maximum ambient temperature in that location. This was consistent with the narrower thermal safety margin (i.e., difference between the mean optimum temperature and mean ambient temperature) of toads in Polonnaruwa, compared to those in Nuwara-Eliya. Importantly, these findings demonstrate that, although thermal sensitivity is considered a conservative trait, differentiation does occur even over a small spatial scale presumably because it offers an adaptive advantage to the population concerned.

ABSTRACT:

Chronic kidney disease (CKD) of unknown etiology is recognized as a major public health challenge and a leading cause of morbidity and mortality in the dry zone in Sri Lanka. CKD is asymptomatic and are diagnosed only in late stages. Evidence points to strong correlation between progression of CKD and kidney fibrosis. Several biochemical markers of renal fibrosis have been associated with progression of CKD. However, no marker is able to predict CKD consistently and accurately before being detected with traditional clinical tests (serum creatinine, and cystatin C, urine albumin or protein, and ultrasound scanning).
In this paper, we hypothesize that fibrosis in the kidney, and therefore the severity of the disease, is reflected in the frequency spectrum of the scattered ultrasound from the kidney. We present a design of a simple ultrasound system, and a set of clinical and laboratory studies to identify spectral characteristics of the scattered ultrasound wave from the kidney that correlates with CKD. We believe that spectral parameters identified in these studies can be used to detect and stratify CKD at an earlier stage than what is possible with current markers of CKD.

ABSTRACT:

Chlorophyll content of a water sample is used as an indirect estimate for the nutrient level of the sample. Optical spectroscopic techniques are widely used to estimate chlorophyll contents of water samples. However, in a complex environment such an urban lake, there are many other pollutant constituent exists. Hence it is difficult to determine the pollutant level only by investigating the chlorophyll signatures. A study is carried out by collecting water samples from different spatial location of Beira Lake, Colombo (29º 52’N, 77º 53’E, 0.0001 m above mean sea level) and fluorescence spectrum excited at 405 nm and absorption spectrum were obtained for each samples. Despite spectral signatures of chlorophyll, spectral signatures of different polluted constituents were observed in both fluorescence and absorption spectra of the every sample. Obtained data set was compressed using singular value decomposition and used first two components which carry 62% of information. It was found that the samples got into four clusters with cophenetic correlation coefficient of 0.76 when the compressed data set was clustered using K-means algorithm. Water samples from the locations near Gangarama Simamalakaya, near Sri Uttarananda Mawatha and near floating market shows highest polluted level. It is evident that in the absorption spectra also 775 nm peak were found which characteristics an infestation of green photosynthetic bacteria due to stagnation. Water quality of Beira Lake near Lake House clustered into two polluted levels. And highest absorption intensity and lowest fluorescence intensities of polluted constituents show in the upper part of the …

ABSTRACT:

We describe the development of a novel versatile optical platform for active and passive remote sensing of environmental parameters. Applications include assessment of vegetation status and water quality. The system is also adapted for ecological studies, such as identification of flying insects including agricultural pests. The system is based on two mid-size amateur astronomy telescopes, continuous-wave diode lasers at different wavelengths ranging from violet to the near infrared, and detector facilities including quadrant photodiodes, two-dimensional and line scan charge-coupled device cameras, and a compact digital spectrometer. Application examples include remote Ramanlaser-induced fluorescence monitoring of water quality at 120 m distance, and insect identification at kilometer ranges using the recorded wing beat frequency and its spectrum of overtones. Because of the low cost this developmental …

ABSTRACT:

Comparison of material usage and cost of two types of cross-flow steam condensers is reported in this study which can be used for water desalination in conjunction with a parabolic trough solar energy concentrator plant. Traditional shell and tube condensers (where steam flows inside the tubes) and surface condensers (where steam flows in the shell and cooling water flows in the tubes) are considered in this study. It has been found that the energy production from the PTC of dimensions 4.5 m× 4.8 m with an aperture area of 21.6 m2 was 19.4 kW. It has been calculated that the distilled water production capacity of the solar energy harnessing system per day is 55.6 l, assuming solar irradiance to be 0.9 kW m-2 and the efficiency of solar energy harnessing system as 50% if the sun is available for four hours. The cooling water input temperature was assumed to be 30 C. The minimum length required for a SS 304 tube of Ø 9.5 mm was 7.16 m for the traditional condenser and 1.30 m for the surface condenser. The efficiency of the traditional condenser reduced due to the formation of a condensed water layer on the surface of the tube, as it acts as a thermal barrier. However, in the surface condenser, efficiency was enhanced due to easy condensation while increasing the system pressure. Further, efficiency is enhanced due to density separation of wet vapour by changing the flow direction near the wet sump. Fabrication cost and maintenance cost are also found to be less in the surface condenser. As such, it can be concluded that use of surface condenser is the most cost effective method, which uses a smaller amount of material making the …

ABSTRACT:

Parameters of the Road-Vehicle-Load system influence the vibration effects generated at vehicular road transportation. Vertical vibration acceleration (PSDmax) experienced by the tomato boxes and tomatoes within the box was studied using the popular transport means in Illukkumbura area in Matale. The road quality was estimated using the International Road Roughness Index (IRI). Fully loaded Mitsubishi Canter truck at an average speed of 20 kmh-1 on a road rated at IRI between 2 to 3.5 mm/m registered increasing trend in the PSD of vibration from the front side towards the rear side of the truck in the horizontal direction. The observed average PSD values are in the approximate ratio, front: middle: rear≈ 1: 3: 6. Also the PSD of the vibration was found to be amplified from the bottom stack towards the topmost stack in the vertical direction. The observed average PSD values at 1st, 2nd, 3rd, and 4th stacks are in the approximate ratio, 1: 1: 1.5: 2.5. PSD of vibration was studied with a fully loaded truck at different speeds on a road consisting of segments rated at varying IRI. The fully loaded truck at different speeds on a road consisting of segments rated at varying IRI registered varying PSD values of vibration. Even at lower speeds such as 25 kmh-1 the vibration acceleration produced at “poor” quality (IRI> 5 mm/m) roads was nearly 4 times higher compared to that produced at “fair”(IRI 2 to 3.5 mm/m) or “good” quality (IRI 0.9 to 2 mm/m) roads. Registered pattern of the PSD appears to be similar at the tomato boxes and at the tomatoes within the same box.

ABSTRACT:

In this paper, a novel detection scheme for the monitoring of insect ecosystems is presented. Our method is based on the remote acquisition of passive sunlight scattering by two insect species. Procedures to identify rare events in remote dark-field spectroscopy are explained. We further demonstrate how to reduce the spectral representation, and how to discriminate between sexes, using a hierarchical clustering analysis. One-day cycle showing the temporal activities of the two sexes as well as data on activity patterns in relation to temperature and wind is presented. We also give a few examples of the potential use of the technique for studying interactions between sexes on a time scale of milliseconds.

ABSTRACT:

A simple polarized-based diffuse reflectance imaging system has been developed. The system is designed for both in vivo and in vitro imaging of agricultural specimen in the visible region. The system uses a commercial web camera and a halogen lamp that makes it relatively simple and less expensive for diagnostic research and teaching. The system has been used to demonstrate the difference between a yellow colour of a diseased cassava leaf and that of a senescence cassava leaf qualitatively using diffused reflectance images. Predicting the area of the sample using a method of counting dark pixels is presented. This method avoids complex and more computational power required by edge detection algorithms. The performance of the suggested method can be seen for 50 samples of leaves. This suggest that polarized diffused reflectance image lends itself to extraction of physical information.

ABSTRACT:

We describe the development of a novel multispectral microscope, based on light-emitting diodes, capable of acquiring megapixel images in thirteen spectral bands from the ultraviolet to the near infrared. The system captures images and spectra in transmittance, reflectance, and scattering modes. We present as examples of applications ground truth measurements for remote sensing and parasitology diagnostics. The system is a general purpose scientific instrument that could be used to develop dedicated simplified instruments with optimal bands and mode selection.

ABSTRACT:

Simultaneous assessment of the spectroscopic absorption signal of gas enclosed in a scattering medium and the corresponding optical path length of the probing light is demonstrated using a single setup. Sensitive gas absorption measurements are performed by a tunable diode laser using wavelength-modulation spectroscopy, while the path length is evaluated by the frequency-modulated cw technique commonly used in the field of telecommunication. Proof-of-principle measurements are demonstrated with water vapor as the absorbing gas and using polystyrene foam as an inhomogeneously scattering medium. The combination of these techniques opens up new possibilities for straightforward evaluation of gas presence and exchange in scattering media.