The reproductive biology of intertidal klipfish (Perciformes: Clinidae) in South Africa

The reproductive biology of six species of viviparous intertidal clinid fish was investigated. Fish were collected monthly from intertidal rock pools between May 1992 and May 1993. Sex ratios varied between 36% female in Clinus acuminatus to 53% female in C. superciliosus, although this was only significantly different from a 50:50 ratio in C. acuminatus (χ2; p<0,05). Size at maturity was greater in females than males of all species and was related to maximium attainable size. Gonad mass varied between 2,6% and 11,6% body mass in males, in males, and reached a maximum of 27,9% in females of C. agilis. In five of the species studied, increases in relative gonad mass of males from March to August were followed by increases in gonad mass of females between September and February, suggesting a gestation period of 4-6 months. Only C. superciliosus indicated no seasonal trends in gonad development. Juveniles recruited to intertidal rock pools in summer at a total length of between 20 and 25 mm. Up to nine broods of eggs and embryos of different ages were found in the gonads at one time, although there was no relationship between the number of broods and fish size. The total number of reproductive elements (eggs and embryos), however, increased with fish mass in all species. Reproductive potential, calculated as the mean number of broods per mature female multiplied by the mean number of reproductive elements per female, varied from a high of 2843 in C. acuminatus to 237 in Muraenoclinus dorsalis

The Intertidal fish fauna of the west coast of South Africa — species, community and biogeographic patterns

In the first quantitative survey of intertidal fish from the South African west coast 62 intertidal rock pools were sampled at two sites, using the ichthyocide rotenone. A total of 2 022 fish representing 14 species belonging to only two families — the Clinidae (88–98% by number) and the Gobiesocidae (12–2%) — were caught. Clinus superciliosus, C. heterodon and the gobiesocid Chorisochismus dentex were the most abundant species in terms of both numbers and biomass. Vertical zonation of individual species on the shore indicated little separation of the habitat between species, although some species exhibited size-specific partitioning of the shore. Relationships between fish distribution and abundance and rock pool characteristics were elucidated by means of stepwise multiple regression, both at the whole community and individual species levels. The abundances of individual species were best predicted by pool size, although some species also showed an association with weed cover. For the community as a whole, the number of species present, the total number of fish and the total biomass in any pool were all dependent on pool size, height above LWS and amount of available cover. Relative to other South African sites the west coast has a low diversity of intertidal fish, combined with a high degree of dominance and a low level of habitat separation

Some factors affecting the efficiency of potato production, under Al–Ghab plain conditions, Syrian Arab Republic

ArticleData were collected by a field survey of 300 farmers from Al–Ghab region (Syria) during 2014–2015. The non–parametric Data Envelopment was used in analyzing the Technical efficiency. The relationship between farm size and production efficiency was considered. Technical efficiency amounted about 53% and most of farms are operating at low level of technical efficiency. The relationship between farm size and productivity efficiency is Non– linear, it decreases from small to medium farm size and then increases as the size increase. Large farms have the higher net farm income per thousand square metersand are the most efficient technically followed by small and medium farm size. To disclose that factors causing the technical efficiency, Two–limit Tobit Regression Model was used. The calculated results showed that, Household Size, Occupation, Farm Size, Experience in Farming, Seed Type and Membership are factors that cause the technical inefficiency potato farming at Al–Ghab region. Therefore, the Syrian Planning Board and Decision Makers should take this results into account when they draw their plans to improve farmer's skills by allocating more investment in farm research and extension programmers

Perdeuterated cyanobiphenyl liquid crystals for infrared applications

Perdeuterated 4'-pentyl-4-cyanobiphenyl (D5CB) was synthesized and its physical properties evaluated and compared to those of 5CB. D5CB retains physical properties similar to those of 5CB, such as phase transition temperatures, dielectric constants, and refractive indices. An outstanding feature of D5CB is that it exhibits a much cleaner and reduced infrared absorption. Perdeuteration, therefore, extends the usable range of liquid crystals to the mid infrared by significantly reducing the absorption in the near infrared, which is essential for telecom applications

Submicron silicon powder production in an aerosol reactor

Powder synthesis by thermally induced vapor phase reactions is described. The powder generated by this technique consists of spherical, nonagglomerated particles of high purity. The particles are uniform in size, in the 0.1–0.2 µm size range. Most of the particles are crystalline spheres. A small fraction of the spheres are amorphous. Chain agglomerates account for less than 1% of the spherules

On the three-dimensional temporal spectrum of stretched vortices

The three-dimensional stability problem of a stretched stationary vortex is addressed in this letter. More specifically, we prove that the discrete part of the temporal spectrum is only associated with two-dimensional perturbations.Comment: 4 pages, RevTeX, submitted to PR

Design of Primary Feeds for 32m KDDI Antenna System IBA-4 in Cassegrain Configuration

Physically large dimensional dish antennas in Cassegrain configuration have played an important role in satellite communications during the past several decades. Recently, however, emerging new technologies have begun to displace these elegant antennas in professional telecommunication service due to their lower operating costs. A beneficial aspect of this transitional situation is that it has created opportunities for amateur radio enthusiasts to use these soon-to-be-retired dish antenna systems for limited experimental testing. Adaptation of these professionally designed antennas to bands allocated for amateur radio service presents excellent educational opportunities in using antenna engineering skills and the use of modern electromagnetic simulation software provides a novel perspective for these antenna design and transformation tasks

Uber die Luminescenz des Luminols. VII. Die Wirkung von Fremdstoffzusatz auf die Luminolreaktion

Es wurde die Wirkung von Fremdstoffzusatz auf die Chemiluminiscenz des Luminols bei Anwesenheit von verschiedenen Katalysatoren mit komplex gebundenem Eisen untersucht. Die Fremdstoffe wirken loschend auf die Lumilnescenz, oder erhohen ihre maximale Helligkeit. Es konnte zwischen wahrer Inhibitorwirkung, Komplexbildung, Losungsmitteleinfluss und Elektrolytwirkung im Sinne der Bronstedschen Theorie unterschieden werden

Uber die Luminescenz des Luminols. VII. Die Wirkung von Fremdstoffzusatz auf die Luminolreaktion

Es wurde die Wirkung von Fremdstoffzusatz auf die Chemiluminiscenz des Luminols bei Anwesenheit von verschiedenen Katalysatoren mit komplex gebundenem Eisen untersucht. Die Fremdstoffe wirken loschend auf die Lumilnescenz, oder erhohen ihre maximale Helligkeit. Es konnte zwischen wahrer Inhibitorwirkung, Komplexbildung, Losungsmitteleinfluss und Elektrolytwirkung im Sinne der Bronstedschen Theorie unterschieden werden

Evolution of central pattern generators for the control of a five-link bipedal walking mechanism

Central pattern generators (CPGs), with a basis is neurophysiological studies, are a type of neural network for the generation of rhythmic motion. While CPGs are being increasingly used in robot control, most applications are hand-tuned for a specific task and it is acknowledged in the field that generic methods and design principles for creating individual networks for a given task are lacking. This study presents an approach where the connectivity and oscillatory parameters of a CPG network are determined by an evolutionary algorithm with fitness evaluations in a realistic simulation with accurate physics. We apply this technique to a five-link planar walking mechanism to demonstrate its feasibility and performance. In addition, to see whether results from simulation can be acceptably transferred to real robot hardware, the best evolved CPG network is also tested on a real mechanism. Our results also confirm that the biologically inspired CPG model is well suited for legged locomotion, since a diverse manifestation of networks have been observed to succeed in fitness simulations during evolution.Comment: 11 pages, 9 figures; substantial revision of content, organization, and quantitative result