http://dr.lib.sjp.ac.lk/handle/123456789/750 2026-04-23T10:26:47Z http://dr.lib.sjp.ac.lk/handle/123456789/773 The Types, Morphology and Population Patterns of Metazoan Parasites of Amblygaster clupeoides in Sri Lanka Piyasiri, Swarna; Wijesinghe, Sujatha L.A. The present investigation is a survey of endo- and ecto-parasites of the marine fish Amblygaster clupeoides, Gal Hurulla, from Trincomalee. The scope of the survey is to record the types of parasites found in A. clupeoides, to describe their morphology for identification purposes and to analyze the population dynamics of the endo-parasites. Nine different parasitic types, both ecto-parasites, (caligids, copepods' gastropods and isopods) and endo-parasites (mites.trematodes and tnematodes.l are recorded from this nine-month survey. Morphological features of the parasites are described in detail for identification purposes. Finally, the population patterns of the endo-parasites were analyzed. This survey reveals that the parasites of A. clupeoides are quite diversified. The commonest parasite is Hemiurus Sp. where 1,242 organisms were found. The second most abundant parasite is a trematode parasite belonging to the sub-order Prosostornata. Other parasitic types were observed only in low numbers. 1989-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/772 Stable Ultra-fast High Power CO2 Laser Pulse Generation Perera, I.K. Some possible approaches towards the generation of ultra-fast infra - red COI laser pulses are discussed. Of these the technique of injection modelocking in particular, which has been applied to a wide range of CO2 oscillators, appear to be the most suitable for large aperture high power laser systems. This technique, which essentially consists of the injection of a low power short pulse into the slave laser cavity, to control the temporal behaviour of its emitted radiation, has also permitted the wavelength control of non - dispersive TEA CO2 laser systems, producing single wavelength ultra - fast CO2 laser pulses in the GW power range. The experimental results obtained are reported and compared with the predictions of a simple theoretical analysis. Regions of broadening of the injected short pulse have been identified and the pulse compression techniques employed to overcome this intrinsio broadening. along with the simple theoretical models developed to analyse the various pulse shaping effects in the amplifying medium, are also described. 1989-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/771 Effects of Atropine on Fertility of Male Rats Ratnasooriya, W.D. Insertion of silastic rods containing 25% and 50% atropine adjacent to the epididymis of rats produced a significant suppression in fertility which was temporary with the lower dose and permanent with the higher dose. Both doses also impaired the motility of epididymal spermatozoa and nervemediated contractile response of isolated vasa deferentia. In addition, the higher dose caused a significant reduction in the mating frequency. It is concluded that the antifertility effect resulted primarily from oligospermia due to dysfunotioning of seminal emission and/or ejaculation. 1989-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/770 Effect of Two Methods of Sampling on the Oothecal Parasites of Periplaneta americana (L.) Kumarasinghe, N.C.; Edirisinghe, J.P. Empty and live oothecae of P. americana found in houses were separately sampled to determine natural parasitism levels of the two oothecal parasites E. appendigaster and T. hagenowii. When a quarter of the live oothecae at a site was removed and sampled for 12 months, T. hagenowii was found to be the dominant parasite with a mean parasitism level of 30.5 %, compared to E. appendigaster with a parasitism level of 8.1 %. When all the empty oothecae were removed from the same sites and sampled in the following 12 months the two oothecal parasites gave equal levels of parasitism, where each species parasitized a third of the total oothecal population. When from two separate sites either empty or live ootheoae were removed concurrently, parasitism levels obtained were similar to those recorded when each type of ootheca was removed from the same sites but in two different years. The study indicates that the removal of even a quarter of the live P. americana oothecae, which represents a sampling method with no replacement has adverse effects on E. appendigaster populations as compared with T. hagenowii. The adverse effect on E. appendigaster populations due to a sampling method with no replacement stems from the low fecundity of this species together with the habit of laying a single egg in an oothecae that yields only a single parasite at emergence. 1989-01-01T00:00:00Z