Showing papers by "University of Peradeniya published in 1982"
TL;DR: In this paper, three risky-choice models are compared to explain rice producer behavior: multiple (two)-attribute utility maximization, single (profit)-attribute UMLM, and expected profit maximization.
Abstract: Sri Lanka rice farmers are faced with a choice between traditional and high-yielding rice varieties. Three risky-choice models are compared to explain producer behavior. Forty farmers with typically small rice areas were studied. Choice criteria compared were multiple (two)-attribute utility maximization, single (profit)-attribute utility maximization, and expected profit maximization. Expected utility maximization performed better than expected profit maximization; single-attribute utility maximization outperformed the more complex multiattribute utility model. The importance of careful elicitation of subjective probability distributions is emphasized. Rice farmers appear to allocate their land between available technologies in an economically rational way.
78 citations
TL;DR: In this article, three experiments were conducted to evaluate the effectiveness of urea as a source of ammonia in an "ensiling" process for improving the nutritive value of chopped rice straw.
56 citations
TL;DR: A survey carried out on the incidence of cardiovascular diseases in Sri Lanka in relation to the hardness of drinking water reveals that a correlation exists which is geographically related as mentioned in this paper, however, this correlation cannot be considered as a causal relationship and other factors possibly exist that could also play a major role in the occurrence of cardiovascular disease, e.g. trace elements.
Abstract: A survey carried out on the incidence of cardiovascular diseases in Sri Lanka in relation to the hardness of drinking water reveals that a correlation exists which is geographically related. This correlation however, cannot be considered as a causal relationship and other factors possibly exist that could also play a major role in the incidence of cardiovascular diseases, e.g. trace elements.
41 citations
TL;DR: In this article, a new lupane derivative isolated from Pleurostylia opposita has been assigned the structure 6,β-hydroxy-lup-20(29)-en-3-one, using spectral evidence and chemical interconversions.
33 citations
TL;DR: A new polyphenol, stemonoporol, has been isolated from four species of Stemonoporus and the polyphenols, copalliferol A and vaticaffinol are reported for the second time.
32 citations
TL;DR: A detailed chemical investigation of extracts of the bark, leaf and timber of Horsfieldia iryaghedhi collected in Sri Lanka led to the isolation of (+)-asarinin, dodecanoylphloroglucinol and (−)-dihydrocubebin.
31 citations
TL;DR: A methanolic extract of the plant Elephantopus scaber was found to contain lupeol, stigmasterol and a new germacranolide dilactone 11,13-dihydrodeoxyelephantopin this paper.
31 citations
TL;DR: In this article, the phenolic fraction of the chloroform extract of the timber of Hypericum mysorense was extracted and a new natural product, 2-hydroxy-3methoxyxanthone, was identified.
29 citations
TL;DR: A new lignan, horsfieldin [2-(3-hydroxy-4-methoxyphenyl)-6-(3,4-methylenedioxyphensyl)-3,7-dioxabicyclo(3,3,0) octane], d -asarinin, (−)-dihydrocubebin, dodecanoylphloroglucinol, myristic acid, trimyristin and sitosterol have been isolated and characterized from the hot methanol extract of Horsfieldia
25 citations
TL;DR: The leopard Panthera pardus fusca was once common and widespread throughout the whole of Sri Lanka (Ceylon). Its numbers have declined sharply in the last 100 years owing to the combined effects of hunting and habitat destruction, processes still very much in evidence today as discussed by the authors.
22 citations
TL;DR: The barks of Carapa granata and Ceriops fagal have been identified as two new tannin rich sources.
Abstract: Abstract : Several Sri Lankan plants have been assayed for their tannin content. Percenta~ e total tannins as determined by the hide powder method have been compared with the results obtained by the polyclar adsorption method. Infra-red spectroscopy has been used to classify the tannins isolated as either belonging to the condensed type or hydrolysable type. The barks of Carapa granata and Ceriops fagal have been identified as two new tannin rich sources.
TL;DR: The bark of Calophyllum calaba var calaba contains a new xanthone, 2,8-di-(3-methylbut-2-enyl)-1,3-dihydroxy-7-methoxyxanthone (calocalabaxanthone) as discussed by the authors.
TL;DR: The methanol extract of the brown seaweed Stoechospermum marginatum was found to inhibit the growth of Staphylococcus aureus and the active constituents were found to be a mixture of diterpenoid monoacetates having the spatane skeleton.
TL;DR: In this paper, the authors investigated organic constituents present in the Muthurajawela peat deposit of Sri Lanka, and reported the variations with depth of sitosterol and stigmastane, which were found to be major constituents of extracts and hence, were selected to study the process of diagenesis.
TL;DR: Conception during January to March led to the shortest calving interval, and during October to December to the longest, and the highest percentage of conceptions occurred some 2–5 months after the peak rainfall.
Journal Article•
Journal Article•
TL;DR: The study of the tonal variations of aerial photographs showing the vegetational cover in the Jaffna Peninsula of the north of Sri Lanka clearly points to the progressive formation of spits and lagoons as mentioned in this paper.
Abstract: The study of the tonal variations of aerial photographs showing the vegetational cover in the Jaffna Peninsula of the north of Sri Lanka clearly points to the progressive formation of spits and lagoons. The contrasting tonal variations of the vegetation found in the emerging lands of different ages can be used to some extent effectively in the delineation of lands in a chronological sequence as exemplified by studies in the Karativu island.
TL;DR: A new flavonoid with an unusual B-ring oxidation pattern, 5,5′-dihydroxy-6,7,2′,3′-tetramethoxyflavone was characterized from bud exudates of Gardenia cramerii and G. fosbergii, two species endemic to Sri Lanka.
TL;DR: Laterites occur extensively in the lowlands of Sri Lanka whereas these are observed as localized outcrops in the uplands and the highlands as mentioned in this paper, where Al-rich zones are found between and beneath harder Fe-rich layers.
Abstract: Laterites occur extensively in the lowlands of Sri Lanka whereas these are observed as localized outcrops in the uplands and the highlands. In lateritis weathering profiles, Al-rich zones are found between and beneath harder Fe-rich layers. The processes of lateritisation and bauxitisation have produced residual products enriched in both Fe2O3 and Al2O3. In the lowlands and uplands the lateritisation processes have prevailed and the bauxitisation trend is more pronounced in the highlands.
TL;DR: In this paper, the off-resonance decoupling, inversion recovery and lanthanide induced shift techniques were used to assign signals for 27-hydroxyfriedelane, kokoonol (27-hydroxylenedilane-3,21-dione) and kokoenononol to the 13C NMR spectra.
Abstract: 13C NMR spectra of 27-hydroxyfriedelane, kokoonol (27-hydroxyfriedelan-3-one) and kokoononol (27-hydroxyfriedelan-3,21-dione) have been recorded and signals assigned using the off-resonance decoupling, inversion recovery and lanthanide induced shift techniques.
TL;DR: Trematodes and nematodes are recorded for the first time, and described, from the endemic caecilians Ichthyophis glutinosus and I. orthoplicatus Taylor, 1965 of Sri Lanka.
Abstract: Trematodes and nematodes are recorded for the first time, and described, from the endemic caecilians Ichthyophis glutinosus (L) and I. orthoplicatus Taylor, 1965 of Sri Lanka. The trematodes are of the species Gorgoderina carli Baer, 1930, from the urinary bladder, and Mesocoelium monas (Rudolphi, 1819) from the small intestine. The nematodes are referred to the species Rhabdias escheri Baer, 1930, from the body cavity and lungs, a new host-record; Pelodera chabaudi sp. nov., from the stomach, small intestine and rectum; and Meteterakis sinharajensis Crusz and Ching, 1976, from the rectum, also a new host-record. Pelodera chabaudi is recognised as a new species on the basis of the arrangment of the bursal papillae, the very prominent pair of fleshy papillae on the cloacal elevation, and the markedly anteriad position of the free proximal ends of the distally fused spicules.
TL;DR: Triterpene quinone-methides, lupenone, β-amyrin, dulcitol, and sitosterol have been isolated from the timber, root and leaf extracts of Gymnosporia emarginata as discussed by the authors.
TL;DR: In this paper, a pot experiment was conducted with two rice varieties grown under flooded conditions to evaluate five chemical extractants,viz: 1N NH4OAc (pH 4.6), 0.05N HCl, 0.01M CaCl2 and 0.2M MgSO4 for extraction of available Zn and Cu.
Abstract: A pot experiment was conducted with two rice varieties grown under flooded conditions to evaluate five chemical extractants,viz: 1N NH4OAc (pH 4.6), 0.01M EDTA-1M (NH4)2CO3 (pH 8.6), 0.05N HCl, 0.01M CaCl2 and 0.2M MgSO4 for extraction of ‘available’ Zn and Cu. Soil Zn and Cu extracted (a) from dry soils before puddling and (b) from wet soils at four and eight week after transplanting were correlated with plant Cu and Zn contents. All extractants gave significant correlations with plant Zn. Highest correlation was obtained with NH4OAc followed by HCl. Zinc extracted from dry soils correlated significantly with that from wet soils. Extractable Zn decreased slightly from zero to four weeks after flooding but increased subsequently. Ammonium acetate, HCl and EDTA extracted approximately equal amounts of Zn.
TL;DR: The high by-pass ability of STL protein appears to make it a suitable feed for growing calves and milking cows.
TL;DR: In this article, it was shown that hermonionic acid is 2.0-[2-(3-methylbut-2-enyl)-3-methoxy- 4-hydroxy-5-(3,7-dimethyl octa-2,6-dienyl]-4-mETHO-6-hydroxylbenzoic acid.
TL;DR: In this paper, three triterpenes obtained from the inner bark of Kokoona zeylanica have been identified as friedelin, D:A-friedo-olean-3, 21-dione and 21α-hydroxy-D.
TL;DR: The water pollution levels of Kandy Lake in Sri Lanka were monitored to probe the impacts and influences of urban environment in a developing country as discussed by the authors, which indicated the adversities of human involvements with nature and provided a good case study for human influence on water pollution.
TL;DR: A survey of on the incidence of dental diseases and the distribution of fluoride in drinking water wells in Sri Lanka, confirms that a distinct causal relationship exists and is clearly geographically related.
Abstract: A survey of on the incidence of dental diseases and the distribution of fluoride in drinking water wells in Sri Lanka, confirms that a distinct causal relationship exists and is clearly geographically related A similar study on the incidence of total cancer in Sri Lanka in relation to environmental factors such as rainfall, concentration of total dissolved ions, hardness of drinking well water, etc showed an association resting entirely upon correlation
TL;DR: During the esterification of acid chlorides with thallium and potassium salts of 19-norethisterone, 17-enol ester were isolated and the enol esters are formed Via the intermediate, 4-estrene-3,17-dione.