https://commons.ru.ac.za/vital/access/manager/Index en-us 5 https://commons.ru.ac.za/vital/access/manager/Repository/vital:2954 Wed 12 Oct 2022 12:32:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2999 Wed 12 Oct 2022 10:14:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3282 Wed 12 Oct 2022 10:11:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2411 Wed 12 May 2021 23:39:08 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4221 Wed 12 May 2021 23:24:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2650 Wed 12 May 2021 23:18:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4953 Wed 12 May 2021 22:55:19 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1500 Wed 12 May 2021 22:53:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2802 Wed 12 May 2021 22:45:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2808 Wed 12 May 2021 22:28:51 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2133 Wed 12 May 2021 20:29:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2416 Wed 12 May 2021 20:26:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2788 Wed 12 May 2021 20:14:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1665 Wed 12 May 2021 20:04:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5219 Wed 12 May 2021 19:45:13 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2714 Wed 12 May 2021 19:36:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3197 Wed 12 May 2021 19:30:49 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4934 Wed 12 May 2021 19:21:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2233 Wed 12 May 2021 19:15:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4826 Wed 12 May 2021 19:12:49 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1578 Wed 12 May 2021 19:05:51 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5226 Wed 12 May 2021 19:02:54 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4997 Wed 12 May 2021 18:59:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5174 Wed 12 May 2021 18:52:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3116 Wed 12 May 2021 18:50:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1499 Wed 12 May 2021 18:36:38 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2811 Wed 12 May 2021 18:29:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4966 Wed 12 May 2021 18:26:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3595 Wed 12 May 2021 18:21:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5264 Wed 12 May 2021 18:15:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:21066 Wed 12 May 2021 18:02:42 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1779 Wed 12 May 2021 17:54:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2978 Wed 12 May 2021 17:51:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4660 Wed 12 May 2021 17:50:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4339 Wed 12 May 2021 17:44:25 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2654 Wed 12 May 2021 17:40:03 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1703 Wed 12 May 2021 17:38:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4379 Wed 12 May 2021 17:27:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4351 Wed 12 May 2021 17:26:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4342 Wed 12 May 2021 17:11:34 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1601 Wed 12 May 2021 16:49:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1799 Wed 12 May 2021 16:49:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3084 Wed 12 May 2021 16:44:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2430 Wed 12 May 2021 16:35:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5246 Wed 12 May 2021 16:23:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1434 Wed 12 May 2021 16:17:29 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4302 B(s) + gases. Symmetry-controlled routes (based on known and hypothetical crystal structures) for transforming the solid reactant into the solid product were devised as possible decomposition pathways. Lattice energies of the reactants, of the postulated transient intermediate structures and of the final solid products were then estimated by crystal modelling procedures. Profiles of lattice energy changes during the proposed decomposition routes were constructed and any energy barriers were compared with experimental activation energies reported for the thermal decompositions. The crystal modelling was performed with the computer program WMIN. Calculation of the lattice energies involved the development of a model potential for the perfect lattice and the evaluation of the interatomic parameters. The potential was based on the Born model of ionic solids using the Buckingham potential (Ø(r)= Ae⁻r/p - C/r⁶) to describe the short-range energy contribution. Empirical fitting was used to establish reliable interatomic energy parameters. The reliability of the interatomic potentials was assessed by calculating crystal structures and lattice energies (which were not included in the fitting). The particular reactions selected for modelling were the decompositions of the alkaline-earth metal (Ca, Sr, Ba) peroxides and carbonates: M0₂(s) ---> MO(s) + ¹/₂0₂(g) MC0₃(s) ---> MO(s) + CO₂(g)The lattice energies calculated for the known structures were in good agreement with reported values, (except for Ba0₂ and BaC0₃) which provided support for the adequacy of the potential model used. Activation energies calculated for the decomposition of the carbonates were in the correct order but hlgher than experimental values, i. e., 422, 422, 465 and 499 kJ mol̄̄⁻¹ compared to the experimental values of 205, 87(?), 222 and 283 kJ mol̄̄⁻¹ for CaC0₃ (calcite), CaC0₃(aragonite), SrC0₃ and BaC0₃. The values calculated for the peroxides (91 and 100 kJ mol⁻¹ compared to the experimental values of 119 and 185 kJ mol⁻¹ for Sr0₂ and Ba0₂ respectively) were less satisfactory but could be a reflection of the poor structural data used for the peroxides. The significance of this approach to the modelling of solid decompositions is discussed.]]> Wed 12 May 2021 16:15:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1010 Wed 12 May 2021 16:08:12 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3059 Wed 12 May 2021 16:05:20 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5001 Wed 12 May 2021 15:55:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5307 Wed 07 Jul 2021 11:21:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2229 Thu 14 Jul 2022 11:22:31 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4983 Thu 13 May 2021 11:01:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2240 Thu 13 May 2021 08:54:47 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1521 Thu 13 May 2021 08:48:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1604 Thu 13 May 2021 08:44:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2636 Thu 13 May 2021 08:24:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2790 Thu 13 May 2021 08:23:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2223 Thu 13 May 2021 08:03:27 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4939 Thu 13 May 2021 07:37:39 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4830 Thu 13 May 2021 07:36:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4608 Thu 13 May 2021 07:23:21 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5323 1100 mm TL (7 years) and all females >1200 mm TL (8 years) were mature. Females grew faster than males, but in both sexes growth slowed dramatically after maturity. Maximum age recorded was 42 years, but fish older than 27 years were rare. Adult A. japonicus were predominantly found in the nearshore marine environment, but also occurred in estuaries and in the surf zone. Spawning takes place in the nearshore environment, from August to November in Natal, and from October to January in the Southern and South-Eastern Cape regions. A large proportion of the adult population migrate to Natal to spawn, although spawning may continue once they return to the Cape. Early juveniles of 20-30 mm TL recruit into turbid estuaries along the entire east coast, possibly aided by olfactory cues. They appear to remain in the upper reaches of the estuaries where they find suitable food and refuge from predators until they grow to about 150 mm TL. Juveniles larger than this size were found in the middle and lower reaches of estuaries and also in the surf zone. Juvenile A. japonicus (<1000 mm TL) generally did not migrate long distances, but remained as separate sub-stocks until they reached maturity. A. inodorus grows more slowly than A. japonicus, and attains a lower maximum age (25 years) and a smaller maximum size (34 vs 75 kg). There was no significant difference between the growth rates of male and female A. inodorus. Those in the South-Westem Cape initially grew faster than those on the east coast, but growth slowed sooner in the former region with the result that these fish attained a smaller maximum size. Although ripe A. inodorus were sampled throughout the year, there was a distinct spawning season from August to December, with a peak in spring (Sept-Nov). Spawning occurred throughout the study area for this species, in <50 m depth. Size at sexual maturity for A. inodorus was smaller in the South-Eastern Cape than in the Southern Cape. Median size at maturity for females was attained at 310 mm TL (1.3 years) in the former and at 375 mm TL (2.4 years) in the latter region, and the length at which all females were mature was 400 mm (3.5 years) and 550 mm (4.7 years) respectively. For males the estimates of Lso and total maturity were 200 mm (1 year) and 400 mm (2.8 years) for the SouthEastern Cape and 250 mm (1.5 years) and 450 mm (3.4 years) in the Southern Cape. East of Cape Agulhas, A. inodorus was found from just beyond the surf zone to depths of 120 m. Adults occurred predominantly on reef (>20 m) while juveniles were found mainly over soft substrata of sand/mud (5-120 m depth). Early juveniles do not enter estuaries, but apparently recruit to nursery areas immediately beyond the backline of breakers (5-10 m depth), and then move seawards with growth. No juveniles were obtained from the area west of Cape Agulhas as substrates <200 m depth were unsuitable for trawling. Due to lower water temperatures, the adults in this area were found from within the surf zone to depths of only 20 m. East and west of Cape Agulhas there was evidence of offshore dispersal in winter, in response to oceanographic changes. Based upon otolith morphology, juvenile and adult distribution patterns, sizes at sexual maturity and on tagging data, A. inodorus between Cape Point and the Kei River apparently exist as three separate stocks, one in the South-Eastern Cape, one in the Southern Cape and one in the South-Western Cape, with limited exchange. The life-histories of A. japonicus and A. inodorus are discussed in terms of their management. The large size at maturity of A. japonicus together with evidence for considerable human impact on the early juvenile, juvenile, and the adult phases of the life-cycle indicate that estuarine nursery habitats need to be conserved, that the minimum size limit should be increased, and that current bag limits for this species should be reviewed. Although the current minimum size limit provides protection for A. illodorus until maturity, evidence is presented which indicates that at least one and possibly all of the stocks of this species are currently over-exploited. Stock assessment of the South African A. japonicus and A. inodorus resources, and the implementation of effective management strategies, are therefore a matter of urgency.]]> Thu 13 May 2021 07:01:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1472 Thu 13 May 2021 06:50:36 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4019 Thu 13 May 2021 06:49:55 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2968 Thu 13 May 2021 06:43:56 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5261 4 ‰). In addition, it was determined that river flow rate during the month prior to sampling also had a profound effect on species composition in all three regions. Based on the available evidence it is suggested that for most species this is related to conductivity levels rather than flow per se.]]> Thu 13 May 2021 06:39:40 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4426 Thu 13 May 2021 06:16:45 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5753 0.05) within species. I conclude therefore that in these three species spermatogenesis is aseasonal. No conclusions about seasonality of spermatogenesis could be made for S. coeruleoalba owing to the small sample size. Large Graafian follicles occurred in the ovaries of all four species in most months of the year. However, the presence of Graafian follicles can not be taken as an indication of timing of reproduction since they may be remnants of follicles that have not yet degenerated. In D. delphis, T. aduncus and S. coeruleoalba luteal bodies (corpora albicans or corpora lutea) occurred in most months of the year. Active corpora lutea will be present in all months, in some members of the population, since gestation is approximately 12 months. The sperm structure of D. delphis was examined by scanning electron microscopy. The sperm of D. delphis is essentially similar to that described for two other species of Cetacea (Physeter catodon and Tursiops aduncus), having an ellipsoidally shaped head and a short mid-piece with nine mitochondria. The sperm dimensions for D. delphis were head length, 4.4pm; head width, 2.0pm and mid-piece length, 2.4pm. An analysis of foetal age in D. delphis showed that the majority of the foetuses were conceived in January with birth occurring the following summer (December), suggesting that reproduction is seasonal. Neonates of T. aduncus were found throughout the year suggesting aseasonal reproduction. Foetal material was not available for S. coeruleoalba and S. chinensis. Seasonality of reproduction in the four species of dolphins studied has been discussed in relation to feeding, migration and worldwide distribution of the species.]]> Thu 13 May 2021 06:13:37 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5480 Thu 13 May 2021 06:12:50 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1584 Thu 13 May 2021 05:50:32 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1606 Thu 13 May 2021 05:22:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2396 Thu 13 May 2021 05:04:26 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1752 Thu 13 May 2021 05:04:07 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3434 Thu 13 May 2021 04:36:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5482 Thu 13 May 2021 04:31:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5258 Thu 13 May 2021 04:06:41 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1437 Thu 13 May 2021 04:03:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5216 Thu 13 May 2021 03:59:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2405 Thu 13 May 2021 03:56:53 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5050 Thu 13 May 2021 03:50:48 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3195 Thu 13 May 2021 03:48:43 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2097 Thu 13 May 2021 03:37:23 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1807 Thu 13 May 2021 02:55:10 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2225 Thu 13 May 2021 02:51:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4224 Thu 13 May 2021 02:38:09 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4960 Thu 13 May 2021 02:33:15 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4962 Thu 13 May 2021 02:16:17 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2144 Thu 13 May 2021 02:08:01 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2781 Thu 13 May 2021 01:57:18 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3144 Thu 13 May 2021 01:55:51 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5290 Thu 13 May 2021 01:39:46 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4659 Thu 13 May 2021 00:55:24 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:4989 Thu 13 May 2021 00:54:33 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:1616 Thu 13 May 2021 00:37:52 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3150 Thu 13 May 2021 00:16:04 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:3577 Thu 13 May 2021 00:04:28 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2227 Thu 13 May 2021 00:00:00 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:2226 Mon 11 Jul 2022 09:39:58 SAST ]]> https://commons.ru.ac.za/vital/access/manager/Repository/vital:5734 Mon 05 Jul 2021 09:29:39 SAST ]]>