PURSE 2013
Permanent URI for this collection
Browse
Recent Submissions
Now showing 1 - 5 of 275
- ItemThe usefulness of pre employment chest radiography as a health screening method prior to employment(The University of Peradeniya, 2013-07-04) Hewavithana, P. B.; Perera, M. G. R. S.Employers often use tests and other selection procedures to screen applicants prior to employment. The goal of the pre-employment examination is to determine whether an individual is fit to perform his or her job without risk to himself or others. For more than two decades chest radiographs have been performed as a pre employment health assessment among all the permanent staff members in University of Peradeniya. Although researchers in other countries have recently questioned the value of this long standing practice, no attempt has been made to consider this evidence in relation to Sri Lanka. The objective of this study was to determine the usefulness of pre employment chest radiography among the employees of the University of Peradeniya as a health screening method prior to employment, by detecting pulmonary tuberculosis. This was a retrospective study on 702 records of chest radiographs, performed at the Health Centre University of Peradeniya, as a routine medical screening prior to employment, from1st January 1991 to 31st December 2011. Of the 702 chest radiographic reports 685 (97.58%) were normal and 17 (2.42%) were considered as having abnormalities. Among those 17 chest radiography reports, there were 2 with mild cardiomegaly (0.29%), 5 hyper inflated lungs or mild basal emphysema (0.71%), one hilar enlargement (0.14%), one healed rib fracture (0.14%) and 7 thoracic scoliosis (0.10%). There were no positive results with respect to active pulmonary TB. Only one report (0.14%) revealed healed pulmonary tuberculosis. In conclusion, the majority of the study sample had normal chest radiographs whereas only 2 % had abnormal examinations. Chest radiograph could be considered a useful screening tool to exclude chest abnormalities. However it may not be useful as a screening method to exclude pulmonary tuberculosis.
- ItemSubspace separation for performance improvement in fetal cardiac signal extraction(The University of Peradeniya, 2013-07-04) Soysa, W. N. M.; Wijayakulasooriya, J. V.; Godaliyadda, G. M. R. I.; Ekanayake, M. P. B.; Kandauda, I. C.To overcome risks during pregnancy, it is important to generate fetal heart signals with minimal noise/distortion, and with as much information as possible. However, interference of various types of unwanted noisy signals such as maternal heart signal and receiver noise cause difficulty in the interpretation of the fetal heart conditions through the extracted fetal cardiac signal. The maternal heart signal interference can be removed using an adaptive Wiener filter. Cardiac signals captured from maternal abdomen and the chest are used as the reference and the input signals into the Weiner filter, respectively. The Wiener filter attempts to model the path between maternal chest and abdomen, thereby effectively cancelling the maternal cardiac signal from the abdomen sensor measurement. This concept is called the principle of correlation cancellation in the Wiener filter. However, the Wiener filter is incapable of removing uncorrelated signals that are present in the input and the reference signals of the Wiener filter itself. Therefore, noise in the reference signal leaks directly to the extracted signal corrupting it. Further, noise at the filter causes a mismatch in the Wiener filter model. Due to this model mismatch, a mismatch noise is added to the extracted signal further corrupting it. Therefore, it is important to minimize the noise in the Wiener filter input and reference signal. To minimize the sensory noise, normally, standard low pass IIR and FIR filtering techniques are utilized. This eliminates high frequency noise to a reasonable degree. But such techniques are susceptible to high noise environments, which in addition tend to be non- stationary. Therefore, we have proposed an Eigen filter based subspace separation technique. The subspace filters utilized have the capability to realize complicated filter structures, thereby improving performance under noisy conditions when all other methods fail. To verify the performance enhancement of the proposed techniques, we have measured the extracted signals correlation to an ideal benchmark signal under varying noise levels. It was discovered that while the performance of other techniques decayed exponentially, only a slight linear performance degradation occurred in the subspace filters, as noise is increased. This clearly indicates the versatility of the subspace technique under high noise levels. Thereafter, we generated a spectral estimate of the extracted signal for different filter types and used appropriate parameters to generate cluster diagrams. The results further verified how the subspace filter based method best replicated the ideal fetal cardiac signal which is desired.
- ItemSurfactant-assisted synthesis of nanosized precipitated calcium carbonate and magnesium hydroxide from marble(The University of Peradeniya, 2013-07-04) Mantilaka, M. M. M. G. P.; Wijesinghe, W. P. S. L.; Rajapakse, R. M. G.; Karunaratne, D. G. G. P.; Pitawala, H. M. T. G. A.Precipitated Calcium Carbonate (PCC) and magnesium hydroxide (Mg(OH)₂) are products in high demand, and are widely used in Sri Lanka. Therefore, the country spends large sums of money for these products despite there being a high possibility to synthesize them using extensively distributed marbles. However, the production of PCC and Mg(OH)₂ has not yet been achieved. This study describes a novel technique to synthesize nanoparticles of PCC and Mg(OH)₂ simultaneously from Sri Lankan marbles. This is a timely requirement to enhance the utility of Sri Lankan marbles and to reduce the cost of importing these products. Marble samples collected from selected locations were crushed, ground and <100 μm fraction was heated at 1000 °C for 4 h to produce calcined dolomite (CaO.MgO). 5 g of calcined dolomite was dissolved in 100 mL of 0.5 M sucrose solution and stirred for an hour. The solution was filtered under suction to separate the precipitated MgO with impurities from soluble calcium sucrate. 0.5 mL of triton X 100 was mixed with calcium sucrate and then 100 mL of 0.5 M Na₂CO ₃ solution was added dropwise to the mixture to synthesize PCC nanoparticles. The function of triton X 100, a nonionic surfactant was to keep resulting products in nanoscale by preventing particle aggregation. The separated MgO component was dissolved in 1.0 HCl solution and filtered to obtain 25.0 mL of 1.0 M MgCl₂ solution with pH of 6.0. Triton X 100 (0.5 mL) was mixed with 50 mL of 1.0 M NaOH. 25 mL of MgCl₂ solution was added dropwise to the reaction mixture while stirring to synthesize Mg(OH)₂ nanoparticles. The final powders of PCC and Mg(OH)₂ products were dried. X-ray Diffraction (XRD) analysis confirmed the presence of calcite in PCC and brucite in Mg(OH)₂. The estimated average particle sizes of PCC and Mg(OH)₂ products by means of Debye–Scherrer formula were 45.1 nm and 11.8 nm respectively. The products were further characterized by using Fourier transform infrared spectroscopy (FTIR) and Thermo Gravimetric Analysis (TGA). Weight percentage of Ca in the Mg(OH)₂ product was 1.1% and weight percentage of Mg in PCC was 0.6%. These results confirm that both PCC and Mg(OH)₂ nanoparticles can be synthesized using Sri Lankan dolomitic marbles with sufficient quality to meet with commercial requirements.
- ItemSubcutis form of transmissible venereal tumour in a dog: a case report(The University of Peradeniya, 2013-07-04) Karunaratna, A. M. D. S.; Bandara, A. M. R.; Rathnayaka, R. M. D. S.; Lokumarambe, c.; Ariyarathna, H. M. H. S.; Wijayawardhane, K. A. N.Transmissible venereal tumour (TVT) is a common round cell tumour among sexually active dogs. TVT is usually transmitted through copulation, whereas direct transplantation of tumour cells onto abraded or intact mucosae of nasal and oral cavities, eyes and skin can occur either by licking or sniffing of the affected genitalia. The most common clinical signs of TVT are presence of pinkish red, friable, cauliflower-like masses on the mucosae of external genitalia. Masses may also be rarely found in other areas, such as oral mucosae, lips, peritoneum, tonsils, eyes, liver, kidneys, spleen, lungs, musculature and subcutis. The objective of this communication is to enhance the awareness of small animal veterinary practitioners in the diagnosis, treatment and management of the subcutis form of TVT. A four-year-old, intact male boxer dog was presented to the Veterinary Teaching Hospital with the complaint of multiple nodules all over the body, which had been rapidly growing over a two week period. Clinical examination revealed firm and freely movable dermal and subcutaneous nodules, ranging from 0.5-4.0 cm in diameter. Cytology of smears from fine needle aspirations and histopathology of biopsies from nodules revealed the subcutis form of TVT. Thoracic radiographs did not show signs of metastasis. Treatment was initiated to control the tumour and minimise adverse effects of chemotherapy. Therefore, weekly administration of vincristine sulphate (0.025 mg/m², IV) was selected as the chemotherapeutic agent. Amoxicillin-clavulanic acid (20 mg/kg, IV, b.i.d) was administered prophylactically, followed by oral medication of the same to prevent secondary infections which may occur due to chemotherapy-induced immunosuppression. Hepatic supportives, haematinics and anti-ulcer drugs were given to minimise adverse effects of chemotherapy. The animal was closely monitored following treatment. Marked reduction in the size (0.3-2.5 cm) of the dermal and subcutaneous masses was observed five days after initial treatment. A second dose of vincristine sulphate given one week later resulted in complete remission of the tumours. In conclusion, TVT should be considered as a differential diagnosis in cases presented with subcutaneous and dermal nodules.
- ItemModelling of acoustic signals based on optimum pole structure for material based classification(The University of Peradeniya, 2013-07-04) Nettasinghe, D. B. W.; Pollwaththage, N. N.; Ratnayake, T. A.; Wijayakulasooriya, J. V.; Godaliyadda, G. M. R. I.; Ekanayake, M. P. B.In this paper, we utilize an autoregressive (AR) model for acoustic signal modeling and classification. It is shown in this work that through proper estimation of the pole structure classification, performance can be improved for material based classification. Classification based on the acoustic properties of materials and systems, is used in many applications in various fields. For example, sports – Snickometer system in cricket, medical diagnosis - acoustic stethoscopes, automobile fault diagnosis - engine trouble, speech processing - automatic speech recognition. The modelling and classification of these data is performed here using three types of signals generated by the impacts between glass–metal (GM), glass–plastic (GP) and metal– plastic (MP) with a database consisting of forty six signals from each class. These three types of signals were modelled using an AR model structure given by: Though the frequency spectrum can be obtained by directly substituting z=eʲʷ, inaccurate pole locations can result due to resolution limitation. In order to circumvent this resolution issue, we resort to “residue method” which can be described as, where, Aᵢ is the residue corresponding to each pole Pᵢ. In particular, we may interpret that Aᵢ represents the “strength” or the level of contribution of pole Pᵢ. The resultant spectrums were then utilized with the AR model for twenty five coefficients in order to extract parameters for classification. The optimum number of poles were obtained using pole-zero plots, hence two coefficients were selected for the classification. As another method of minimizing the error, the optimum number of poles was selected to be four, since it yielded the minimum squared error. According to this analysis, it was observed that there is a clear separation of the three signals into different cluster regions with a minimal number of false alarms. In conclusion, we show that, signals can be classified according to their acoustic system using AR modelling with the optimum number of poles, as less number of poles will not model the signal accurately and large number of poles will model the noise components as well, which will lead to erroneous results.