Showing papers by "University of Peradeniya published in 1993"

Role of non-timber forest products in the economy of peripheral communities of knuckles national wilderness area of Sri Lanka: A farming systems approach

Abstract: The Knuckles range of forests has been identified as a unique biological resource in Sri Lanka with much biodiversity. It is also important as a watershed which feeds the Mahaweli reservoir system. Having considered the present hazardous land-use practices such as cardamum production and shifting cultivation, the Knuckles range has been declared a national wilderness area. The Forest Department is in the process of preparing the management plan for the area. There are about 48 villages in the vicinity of the forest. This study attempts to estimate the composition of income in the peripheral communities, ticularly the extraction of non-timber forest products (NTFP) from this range of forests. Data were collected using structured questionnaires from 60 households in three villages in the vicinity of the forest. The rural economy is described using a farming systems approach and the net income contributed by each activity in the farming system was estimated. Results show that nine components of the farming system use resources from the village and the forest, with at least 47 plant species used by the villagers for different purposes. Cardamum production and shifting cultivation contribute significantly to the total income of the household, but the majority of households in the study depend upon forest resources to supply some portion of their income. Nevertheless, the monetary value of the annual income generated by NTFP is much lower than income from either cardamum production or shifting cultivation. If cardamum production and shifting cultivation are to be restricted under the conservation program, there could be additional pressure put on NTFP. Therefore, we suggest a study of the natural regen-eration capacity of selected NTFP; such information should be used in finalizing the management plan in the Knuckles range of forests.

Cassava leaves as animal feed: Potential and limitations

Abstract: The nutrient composition and potential productivity of cassava (Manihot esculenta Crantz) leaves are examined, and their usefulness as a protein supplement in animal nutrition in the tropics is reviewed. On average, meal prepared from cassava leaves contains (on a dry matter basis) 210 g kg−1 crude protein, 250 g kg−1 acid detergent fibre, 85 g kg−1 ash, 14.5 g kg−1 calcium and 4.5 g kg−1 phosphorus. Cassava leaf protein is well balanced, except for a deficiency of sulphur-containing amino acids. The presence of hydrocyanic acid and tannins is considered, but a leaf meal with low levels of these anti-nutritional factors may be prepared using simple processing techniques. The most immediate prospects for the use of cassava leaf products are in the following areas: (i) low level inclusion of leaf meal in feed formulations for monogastric animals, and (ii) fresh forage as a protein supplement to low-quality roughages in ruminant feeding. Relevant future research needs are also identified.

A Scale to Assess Severity in Organophosphorus Intoxication: POP Scale:

Abstract: We have developed a clinical scale to assess severity or organophosphorus (OP) intoxication. Five common clinical manifestations of OP poisoning have been selected as parameters, each to be assessed on a 3 point scale varying from 0-2. Poisoning can then be graded as mild (score 0-3), moderate (score 4-7) or severe (score 8-11) when the patient first presents. The scale was validated using two consecutive series of 173 patients with OP poisoning. Correlations between the scores obtained on admission and three outcome variables, namely, death, the need for ventilatory support and the dose of atropine required in the first 24 hours after admission were significant. We believe that this scale would assist in grading severity of OP intoxication at first contact and help in predicting possible outcome.

Physical and biochemical properties of green banana flour

Abstract: Banana flour prepared from two cooking banana varieties, namely ‘Alukehel’ and ‘Monthan’, were evaluated for their physical and biochemical characteristics. The yields of flour averaged 31.3% for ‘Alukehel’ and 25.5% for ‘Monthan’. The pH of the flour ranged from 5.4 to 5.7. The bulk density and particle size distribution were also measured. The average chemical composition (% dry matter) of the flours were as follows: crude protein, 3.2; crude fat, 1.3; ash, 3.7; neutral detergent fiber, 8.9; acid detergent fiber, 3.8; cellulose, 3.1; lignin, 1.0 and hemicellulose, 5.0. Carbohydrate composition indicated the flour to contain 2.8% soluble sugars, 70.0% starch and 12.0% non-starch polysaccharides. Potassium is the predominant mineral in banana flour. Fresh green banana is a good source of vitamin C, but almost 65% is lost during the preparation of flour. Oxalate content (1.1–1.6%) of banana flour is probably nutritionally insignificant. The overall results are suggestive of the potential of green bananas as a source of flour.

Japanese encephalitis in Sri Lanka: comparison of vector and virus ecology in different agro-climatic areas

Abstract: The ecology of Japanese encephalitis (JE) in different agro-climatological areas of Sri Lanka was studied in relation to the abundance of mosquito vectors, infection in domestic livestock, and human infection and disease. There was an inverse correlation between altitude and the abundance of potential JE vectors, as well as JE seroprevalence in domestic livestock and in man. Little or no JE infection was documented above 1200 m elevation. JE seroprevalences in cattle and goats were better predictors of human infection risk than was porcine seroprevalence. In areas with asynchronous porcine infection occurring over many months, high overall JE seroprevalence in pigs was found with little evidence of human infection. Porcine JE infection occurring in synchronous bursts associated with monsoonal rains was correlated with significant bovine, ovine and human seroprevalence in 2 low elevation study areas, Anuradhapura (dry zone) and Ragama (wet zone), with epidemic human JE in the former area and endemic disease in the latter.

Conditioning technique for multiinput-multioutput processes with input saturation

Abstract: The problems of controller windup and directional change in controls, in controllers for multiinput multioutput processes with input saturation, is considered. To avoid the windup problem, a generalisation is proposed for the conditioning technique based antiwindup compensator, by introducing a filtered setpoint. This provides a parameterisation to deal with situations where the original conditioning technique was not suitable. To reduce the effect of directional change in controls due to the multiple saturation, further modifications to the conditioning technique are proposed. An interesting outcome is that the generalised antiwindup compensator due to Astrom and Wittenmark is interpreted in terms of the conditioning technique; moreover, these interpretations are used to introduce modifications to their scheme in order to deal with the problem of directional change in controls.

Prevalence of diabetes mellitus and impaired glucose tolerance in a rural Sri Lankan community.

Abstract: The prevalence of diabetes mellitus and impaired glucose tolerance (IGT) in a rural Sri Lankan community adopting the World Health Organization (WHO) criteria were 25% and 8% respectively The low socioeconomic status, adequate physical exercise and the low prevalence of obesity appear to have not only contributed to the low prevalence of diabetes but also has prevented progression from IGT to overt diabetes

Assessment of masticatory efficiency: new methods appropriate for clinical research in dental practice

Abstract: A new chewing test has been assessed in which the test food was contained in a chewable rubber bag. Six subjects chewed ten single 'unbagged' almonds and ten single 'bagged' almonds. The bagged experiments gave generally similar results to unbagged ones in terms of the particle size distribution; they also proved more acceptable to the subjects and eliminated the serious, undefinable loss of chewed particles that occurs intraorally in conventional (unbagged) tests. In this study an optical scanning method was used which provided a simple, fast measurement of individual particles.

Acidulated pegmatitic mica: A promising new multi-nutrient mineral fertilizer

Abstract: Scrap grade pegmatitic phlogopite mica contains 5–7% K (∼8% K2O), 10–14% Mg (∼23% MgO), 1–2% Ca (∼2.9% CaO), 0.03% Mn and 109 ppm Zn. On acidulation upto 65% of K and Mg and 15–100% Mn and Zn were recovered. Less than 13% of Ca was recovered in solution. Water soluble and Nh4OAc extractable K and Mg of acidulated mica of pegmatitic origin increased a 102 to 103 times compared to untreated mica. Acidulated mica remained non-hygroscopic even when mixed with acids at a 2:1 mica to acid ratio. X-ray diffraction analyses demonstrated that interlayer cations were easily leached from the mica structure leaving behind a kaolinitic residue, compared to the more stable tetrasilicate feldspars. The most significant achievement through these experiments was the yield increase obtained in the greenhouse experiment with rice by using the lowest application rate (200 kg ha−1) so far reported for mica, - an exponential decrease from tonnes/ha previously reported. Acidulated phlogopite mica chips (200 kg ha−1- 4 kg K, 8 kg Mg, trace elements Mn, Zn etc.) gave a yield increase of over 41% compared to a control with recommended muriate of potash and dolomite (17 kg K, 6 kg Mg). The response to acidulated feldspar (500 kg ha−1- 1.5 kg K) and an acidulated feldspar-dolomite combined fertilizer (250 kg ha−1- 0.6 kg K and 6 kg Mg) was not significant. The response to mica clearly shows a multinutrient deficiency in highly weathered tropical soils. The relatively high solubility of the acidulated mica, its range of nutrient element supply, its nonhygroscopic nature and its extremely simple manufacturing process makes mica, a cheap but effective fertilizer for the tropical regions where these nutrients are deficient, especially in highly metamorphosed crystalline terrains.

Interdisciplinary research towards management of non-timber forest resources in lowland rain forests of Sri Lanka

Abstract: Lowland and mid-elevational rainforests of Sri Lanka harbor a relict, endemic-rich flora which is also rich in timber and non-timber forest resources. These forests supply nearly half the total wood requirements of the country and are dwindling rapidly; management of the forests to conserve the biological richness and maintain environmental services is therefore a difficult proposition. This predicament is further compounded by the dependency of rural people on a range of non-timber forest resources for their subsistence and income. A forestry master plan recently prepared for Sri Lanka has not given adequate recognition to the important role played by non-timber forest resources in rural livelihood. This oversight is primarily due to the lack of quantitative information to justify the role of non-timber forest resources in forestry sector development. Forestry policies that ignore these resources often anger local people, leading the villagers to vent their disapproval through destructive actions such as burning timber plantations. Long-term interdisciplinary research in ecology, reproductive and soil biology, ethnobiology, silviculture, rural sociology and resource economics in progress at Sinharaja attempts to address these questions of sustainable development of forest resources in an integrated mode. While research oriented toward conservation investigates both short- and long-term ecosystem dynamics in natural and modified forest stands, utilization-oriented research probes the impact of increased human disturbance, particularly the impact of rural communities on dwindling forest resources, as well as the effect of forest conservation on rural livelihood. These studies continue to seek alternative methods of forest management which are socially acceptable, economically viable, and ecologically sustainable for multiple uses. These methods will assist in the refinement of current forest policies, forestry planning, and the implementation of new policies and plans in Sri Lanka.

Lithium ion conducting Li4−2xGe1−xSxO4 solid electrolytes

Abstract: Pulmonary function tests (FVC, FEV1, FEV1/FVC%, TLCO, single breath CO diffusion), chest x ray film, renal function (serum creatinine and blood urea nitrogen), liver function (serum alanine aminotransferase, aspartate transferase, and alkaline phosphatase, bilirubin, total protein, and albumin), a haematological screen (haemoglobin and packed cell volume), and a general clinical examination were performed on 85 paraquat spraymen (mean spraying time 12 years) and on two control groups (76 factory workers and 79 general workers) frequency matched for age and years of occupational service. All the subjects were men. There were no clinically important differences in any of the measurements made between the study group and the two control groups. In particular the results of the lung function tests, appropriate for paraquat toxicity of the study group, were similar to those of the control groups. The same was true of blood tests for liver and kidney function. The incidence of skin damage, nose bleeds, and nail damage in the study group was slightly higher than in the control groups but lower than the incidence reported for paraquat workers in previous studies. The results of this study confirmed that long term spraying of paraquat, at the concentrations used, produced no adverse health effects, in particular no lung damage, attributable to the occupational use of the herbicide.

An epidemiological study of the health of Sri Lankan tea plantation workers associated with long term exposure to paraquat.

Abstract: Pulmonary function tests (FVC, FEV1, FEV1/FVC%, TLCO, single breath CO diffusion), chest x ray film, renal function (serum creatinine and blood urea nitrogen), liver function (serum alanine aminotransferase, aspartate transferase, and alkaline phosphatase, bilirubin, total protein, and albumin), a haematological screen (haemoglobin and packed cell volume), and a general clinical examination were performed on 85 paraquat spraymen (mean spraying time 12 years) and on two control groups (76 factory workers and 79 general workers) frequency matched for age and years of occupational service. All the subjects were men. There were no clinically important differences in any of the measurements made between the study group and the two control groups. In particular the results of the lung function tests, appropriate for paraquat toxicity of the study group, were similar to those of the control groups. The same was true of blood tests for liver and kidney function. The incidence of skin damage, nose bleeds, and nail damage in the study group was slightly higher than in the control groups but lower than the incidence reported for paraquat workers in previous studies. The results of this study confirmed that long term spraying of paraquat, at the concentrations used, produced no adverse health effects, in particular no lung damage, attributable to the occupational use of the herbicide.

Ecology of the Asian Elephant in lowland dry zone habitats of the Mahaweli River Basin, Sri Lanka

Abstract: The ecology of the Sri Lankan elephant in the Wasgomuwa Strict Nature Reserve and its environs is reported for the first time Seasonal changes in the availability of grazing sites influenced changes in the home range of elephants Availability of such sites in the wet season was limited by agricultural activities Paddylancds, after the harvest of the rice crop in the late -wet season, became important dry season grazing sites In the Reserve and areas outside its southern boundary on the left bank of the Mahawveli River, (a) female herds were seen more often than solitaries (b) female herds were larger and had a higher than expected number ofjuveniles in the dry than in the wet season (c) about 45% of the individuals were juveniles and (d) 74% of adult and sub-adult females had calves Conflict between elephants and farmers will be most intense along the southern and eastern boundaries of the Wasgomuwva National Park, established in 1984 by the addition of new areas predominantly to the northern part of the Wasgomuwva Strict Nature Reserve

Cellular Changes and Time since Death

Abstract: Based on a hypothesis that post-mortem cellular (chiefly nuclear) changes in the white blood cells could reliably be correlated with the time interval since death, (ti), serial observations were made on the counts (total, differential) and light-microscopically observable 'degenerations' of white blood cells obtained from 30 non-refrigerated cadavers (experimental group) and similar cells obtained from 200 hospital patients (control group). While neutrophils degenerated rapidly, lymphocytes did so slowly; the eosinophils and monocytes degenerated at rates between these extremes. In cadaveric blood total counts of identifiable leucocytes on average dropped to zero by 84 hours, identifiable eosinophils and monocytes were first to 'disappear' (by 60 hours), followed by neutrophils (by 66 hours), and finally lymphocytes: identifiable lymphocytes disappeared completely at or around 84 hours from the time of death. This 'differential degeneration' was surprising but useful. Based on the use of all four characteristics--total and differential white cell counts, differential degeneration and morphology of cells--a method for a reasonably exact estimation of ti is presented. The method is appropriate for ti up to 84 hrs (3 1/2 days). Zero white cell counts (total, differential) and bizarre morphology (unidentifiable white blood cells) indicate a ti > 84 hrs. Avenues for further research are indicated.

A longitudinal study of Vero cytotoxin producing Escherichia coli in cattle calves in Sri Lanka.

Abstract: Two cohorts of 10 and 16 calves were followed at weekly or fortnightly intervals from 4-28 and 1-9 weeks respectively to determine whether natural infection by Vero cytotoxin (VT) producing Escherichia coli (VTEC) occurred. Ninety-one of 171 (53%) faecal specimens were VTEC positive and 20-80% of animals at any given time excreted VTEC. Of 104 VTEC strains studied further, 6 different serogroups (O 22.H16; O 25.H5; O 49.H-; O 86.H26; O 88.H25; O 153.H12) and an untypable strain (O? .H21) were identified. All strains belonging to the same serotype had identical profiles of reactivity with DNA probes to toxins VT1 or 2, LTI or II and a probe (CVD419) derived from a plasmid carried by enterohaemorrhagic Escherichia coli O 157.H7. Four of these serotypes were found in the faecal flora of the calves, taken as a group, throughout the 4-month study period. Sixty percent of the strains hybridized with the probe for VT1, 4% with the probe for VT2, and 36% with both probes. Faecal VTEC were significantly associated with overt diarrhoeal illness in animals < 10 weeks of age, but no characteristic profile of markers (serotype or hybridization pattern) in E. coli isolates was associated with diarrhoea. A serological response to VT1 was detected in some animals, but faecal VT1 VTEC excretion persisted in spite of seroconversion. VT1 seroconversion was not associated with diarrhoea. A serological response to VT2 was not detected even in those animals excreting VT2 VTEC in the faeces.

A review of models for predicting the thermomechanical behaviour of soft clays

Abstract: SUMMARY This paper critically examines the use of the modified Cam clay stress-strain model in predicting the thermomechanical behaviour of soft clays. The equations governing the thermomechanical behaviour of a saturated soil are summarized and their methods of solution are briefly discussed. The observed thermomechanical soil behaviour reported in the literature has been compared with the predictions made using the modified Cam clay model. In making these comparisons, two extensions of the well-known modified Cam clay model have been considered: one proposed by Britto et al.' in which heating induces thermal stresses and strains in the soil but has no direct effect on the work hardening, and the other proposed by Hueckel and Borsetto' in which a change in temperature also affects the yield surface. The comparisons are confined to the behaviour of normally and lightly overconsolidated clays, where the modified Cam clay is known to perform well. Apart from the effect of a single heating-cooling loop, cyclic behaviour is not considered. It is concluded that both models provide reasonable predictions under isotropic stress conditions. Although exhaustive comparisons have not been made for deviatoric stress excursions (because of the lack of experimental data), it appears from preliminary studies that neither model performs particularly well for this form of loading.

Classification of epileptic seizures: a hospital-based study of 1,250 patients in a developing country.

Abstract: The 1981 International Classification of Epileptic Seizures (ICES) was used to study the distribution of seizure types in 1,250 patients attending an Epilepsy Clinic in Sri Lanka. Based on seizure symptomatology 94.6% of the cases could be classified, and by adding the routine interictal EEG findings the percentage of classifiable seizures increased to 97%. Partial seizures (73.8% cases) were three times as common as generalized seizures (23.3% cases). Of the partial seizures, simple partial seizures (SPS) accounted for only 0.4% cases, and complex partial seizures (CPS) for 8.8%, whereas partial seizures secondarily generalized (PSGS) accounted for 64.6%. PSGS had simple onset in 12.5% and complex onset in 34.8% of cases. Myoclonic seizures were the commonest of the generalized seizures, accounting for 14.6% of all cases. Tonic-clonic seizures accounted for 7.4% of cases; absence seizures accounted for only 1.3%. The study showed the 1981 ICES to be relevant and applicable in a clinical setting with limited investigatory facilities. Difficulties encountered with regard to certain subcategories could be overcome with minor modifications which made the classification operative. Routine EEG confirmed the diagnosis in a significant number of cases but changed the diagnosis in only a few, confirming that a good standardized questionnaire is the key instrument for classifying epileptic seizures.

Effect of fluidized bed drying on stabilization of rice bran

Abstract: Rice bran was treated in a batch fluidized bed at temperatures starting from 90°C up to 130°C in steps of 10°C for different treatment periods. Drying characteristics of rice bran so obtained were used in a mathematical model to predict the maximum possible storage period of rice bran treated under fluidizing conditions. It was observed that the fluidized bed treatment of rice bran requires much lower treatment times for stabilization of rice bran compared with packed bed processes and therefore could be very attractive in commercial applications.

On the convergence properties of adaptive pole-placement controllers with antiwindup compensators

Abstract: To avoid the windup problem in adaptive pole-placement controllers in the presence of a saturating input, an antiwindup compensator based on a generalization to the conditioning technique is introduced to the controller. This modification to the controller also provides a unified approach to investigate the asymptotic properties of the adaptive controllers with a class of antiwindup compensators, at least, when applied to stable processes. >

Adsorption of fluoride on goethite surfaces-implications on dental epidemiology

Abstract: Fluoride ion interaction with synthetically prepared goethite has been investigated over a range of pH values (4–9) and F− concentrations (10−3−10−5 M). The amount of F− retained by goethite suspensions was found to be a function of pH, media ionic strength, F− concentration, and goethite concentration. The lowest ionic strength (0.001 M KNO3) gave the highest adsorption medium. Uptake was minimal at pH >7 and increased with decreasing pH. Thermodynamic properties for fluoride adsorption at 298 K and 323 K were investigated. The isosteric heat of adsorption (δH r) was calculated and the heterogeneity and homogeneity of the surface examined for goethite. In view of the importance of fluoride in dental health, the interaction of fluoride on goethite in the physical environment has important implications on dental epidemiology.

Saponins of Diploclisia glaucescens

Abstract: The stem of Diploclisia glaucescens afforded vibo-quercitol and four new saponins, whose structures have been established. One saponin has shown acceptable molluscicidal activity.

Lightning radiated electromagnetic fields and high voltage test specifications

Abstract: The authors investigate the response of an F106-B aircraft, modeled by a lumped-parameter transmission line, to microsecond and submicrosecond impulses. Since a very high content of harmonics was observed for a submicrosecond impulse, the authors investigate the equation traditionally used for determining lightning current impulses from measured electric fields and correct this equation. It is found that the use of the zero-to-peak rate of rise of the order 230 kA/ mu s is unwarranted. Impulse voltages with risetimes on the order of 0.02 mu s exert more severe stress on an aircraft structure than a 2- mu s time-to-crest impulse. The harmonic components excited on the airframe have significant energy content in the HF spectrum. The crest voltage values along the structure of the aircraft may exceed the voltage impressed by the lightning electromagnetic pulse (LEMP) or the nuclear electromagnetic pulse (NEMP) due to the resonances excited on the airframe. The submicrosecond risetimes in the electric fields do not indicate submicrosecond time-to-crest values in the lightning currents. >

Salacenonal: A Novel Nortriterpenoid Aldehyde of Biogenetic Significance from Saiacia Reticulata

Abstract: The structure of salacenonal, a novel and biogenetically important 29-nortriterpenoid isolated from Salacia reticulata has been established as 3-hydroxy-2-oxo-29-nor-D:A-friedo-oleana-3(4),20(30)-dien-24-al (1).

Ileal perforation in typhoid: bacteriological and immunological findings.

Abstract: In typhoid perforation patients, Salmonella typhi was isolated from blood in 4%, ileal contents in 23%, peritoneal pus in 13% and from mesenteric lymph nodes in 71%. While isolation of S. typhi was made from patients with less than 4 days of chloramphenicol therapy, cultures were negative from these sites after 5 days of therapy; however, S. typhi appeared to remain viable in the lymph nodes even after such therapy. All isolates of S. typhi were sensitive to chloramphenicol. Significant SAT titers (0 > or = 1/240) were obtained in only 7/21 (33%) of patients. The perforated group had lower geometric mean titers (0-1/138; H-1/46), when compared to matched patients with uncomplicated typhoid fever (0-1/476; H-1/148). This difference was significant (0- p < 0.005; H- p < 0.0025). The two groups (uncomplicated and perforated) showed no significant difference in total serum IgG, IgM and IgA or isohemagglutinin levels, indicating that the apparent hyporeactivity was not due to a generalized humoral immunodeficiency. Mesenteric lymph node histology showed hyporeactivity in both the T cell and B cell zones. These findings are discussed with the suggestion that S. typhi-specific host immunological hyporeactivity could be an explanation for these observations and a basis for the pathogenesis of perforation. Aerobic cultures of the peritoneal pus gave 39 isolates from 25 patients; the predominant isolates were Escherichia coli (24) and Klebsiella pneumoniae (12). On no occasion was S. typhi the predominant isolate. Gentamicin and kanamycin were the only two antibiotics which were consistently effective in vitro against the aerobic isolates from peritoneal pus.

An electromagnetic inverse problem solver for radar: aircraft rotation and tilt measurement

Abstract: A Doppler radar is used to obtain the velocity, altitude, and distance of an aircraft with respect to the radar coordinates. It is shown that the reflected electromagnetic fields picked up by the receiver antenna also contain information on the rotation angle and tilt angle of the aircraft, which could be obtained using a maximum-likelihood estimation algorithm. The electromagnetic signal processing unit estimates the angles of rotation and tilt and the radius of the target modeled as a cylinder using the scattered magnetic field. Specific results showing the application of the estimator are given. >

Chemical decontamination of aniline by redox sensitive mineral surfaces part I: Kinetic Aspects∗

Abstract: Kinetic aspects of the degradation of aniline into various products has been investigated in aqueous suspensions of goethite in 0.001 M NaNO3 over a range of laboratory conditions. A ligand promoted dissolution model was used to define the fate of aniline in a mineral surface mediated reaction system. At a given [H+] concentration the reaction rate was found to be dependent on both aniline and goethite concentrations.