Aspects of the life history of skates from southeastern Australia

The age and growth, reproduction and diet of several skate species in south-east Australia were studied. From studying these life history characteristics it was determined that skates have a relatively low productivity and may therefore be at risk of local extinction if increasingly exploited without appropriate management.

Predation of a small passerine by the Purple-winged Roller Coracias temminckii, an endemic species of Sulawesi

The usual diet of the Purple-winged Roller, a species endemic to Sulawesi, is grasshoppers, locusts, beetles and small lizards. This note describes an observation of this species preying on an adult Eurasian Tree Sparrow Passer montanus. The presence of birds in the diet of other roller species is discussed.

Effect of roller leveling on the bending behaviour of aged steel strip

The common grades of steel used in roll forming are: hot rolled carbon steel, high strength low alloy and recovery annealed cold rolled sheet. These steels are prone to ageing and are often skin passed and/or roller leveled to eliminate ageing as it can lead to problems in forming. In roll forming, shape defects such as bow, twist and camber are considered to be related to very small plastic strains in the longitudinal direction and hence knowledge of the material properties in the elastic plastic transition range is necessary if the process is to be modelled accurately. Previous studies with aluminium have indicated that skin pass rolling can lead to residual stresses in the strip. In this work, the study was extended to aged carbon steel and to the effect of roller leveling on both aged material and strip that had been given a light cold rolling to simulate a skin pass treatment. The results suggest that roller leveling reduced the magnitude of residual stresses resulting from skin pass rolling.

The significant differences observed between tensile and bending test results, at and near, the elastic plastic transition reinforces the need to consider bending properties when assessing the effect of prior processing on strip for roll forming.

Size at maturity and egg capsules of the softnose skates Bathyraja brachyurops (Fowler, 1910) and Bathyraja macloviana (Norman, 1937) (Elasmobranchii: Rajidae) in the SW Atlantic (37 degrees 00'-39 degrees 30'S)

P>The softnose skates Bathyraja brachyurops and Bathyraja macloviana represent an important portion of the skate catches of the Uruguayan trawling fleet in the southwestern Atlantic. From March to October 2004, specimens of these species were collected at 75-200 m depth range in the area situated between latitudes 37 degrees 00'-39 degrees 30'S. For B. brachyurops, total length at which 50% of the specimens were retained by the gear was 68.0 cm for both sexes; T(L50) was estimated at 65.4 cm for males and 67.0 cm for females. For B. macloviana, total length at which 50% of the specimens were retained was 56.0-57.0 cm for both sexes; T(L50) was estimated at 53.5 cm for males and 52.0 cm for females. Egg capsule length varied from 79-91 mm in B. brachyurops and 69-75.5 mm in B. macloviana. In both species, capsules displayed striated surfaces and similar gross morphology, although egg capsules of B. macloviana had more robust anterior horns and a smaller size than those of B. brachyurops. Egg capsules of the latter also exhibited microscopical prickles. Capsule edges were laterally keeled with a groove along the keel, and a straight and transverse velum was present in the egg capsules of both species.

Food resource utilization of the skates Rioraja agassizii (Müller & Henle, 1841) and Psammobatis extenta (Garman, 1913) on the continental shelf off Ubatuba, South-eastern Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Analysis of the influence of pre-loading in the rating life calculation of tapered roller bearings applied to lightweight front-axle differentials

For intricate automotive systems that enclose several components, such as gearboxes, an important aspect of the design is defining the correct assembly parameters. A proper assembly can ensure optimized operating conditions and therefore the components can achieve a longer life. In the case of the support bearings applied to front-axle lightweight differentials, the assembly preload is a major aspect for an adequate performance of the system. During the design phase it is imperative to define reference values to this preload, so the application would endure its requirements. However, with the assistance of computer simulations, it is possible to determine an optimum condition of operation, i.e. optimum pre-load, which would increase the system reliability. This paper presents a study on the influence of preload on the rating life of tapered roller bearings applied to light-weight front axle differentials, evaluating how preload affects several key parameters such as rating life and displacement of components, taking into account the flexibility of the surrounding differential housing. Copyright © 2012 SAE International.

Evolution and historical biogeography of the Eastern Atlantic skates

In my thesis, I tested the hypothesis that the diversification of the Eastern Atlantic skate faunas arose through vicariance rather than dispersal, using combined approach of molecular phylogeny reconstruction and zoogeography (namely historical biogeography). This analyses have been carried out independently on four Rajidae genera belonging to two different tribes: Rajini (Raja and Dipturus) and Amblyrajini (Rajella and Leucoraja). These taxa were selected because they displayed high species diversity and richness of endemic species in the Eastern Atlantic and Mediterranean. The verification of this hypothesis was carried out by reconstructing the best phylogenetic relationships among four genera and 26 species (including several endemism) based on mtDNA and nuDNA gene variation and several statistical approaches. Divergence times of taxa have been estimated based on molecular clock and fossil calibration to explain evolutionary patterns in the context of geological framework. Main issues are (i) the evidence that Eastern Atlantic skate evolution and displacement of species diversity occurred from pulsed geographical speciation (i.e. repeated series of parallel and independent speciation events) started in the Late Eocene-Early Miocene and they have occurred prevalently during Miocene; (ii) such relatively ancient origin of diversification has been allowed the sympatric displacement and evolution of several congeneric taxa likely because they have accumulated huge differences in the genomic and physiological/behavioural phenotypic traits; (iii) recently diverged sister species and taxa showed allopatric or parapatric evolution by the presence of oceanographic or hydrogeographical barriers which likely prevent large mixing between parapatric sister species.

Molecular phylogeny and historical zoogeography of four genera of Eastern Atlantic skates (Rajiformes, Rajidae)

The aim of this study was to reconstruct a solid phylogeny of four genera of the Rajidae family (Chondrichthyans: Batoidea) using a concatenated alignment of mtDNA genes. Then use the resultant tree to estimate divergence time between taxa based on molecular clock and fossil calibration and conduct biogeographic analysis. The intent was to prove that the actual distribution of species of Eastern Atlantic and Mediterranean skates is due to a series of vicariant events. The species considered belongs to two different tribe: Rajini (Raja and Dipturus) and Amblyrajini (Leucoraja and Rajella). The choice of this genera is due to their high presence in the area of interest and to the richness of endemic species. The results show that despite the ancient origin of Rajidae (97 MYA), the Eastern Atlantic and Mediterranean faunas originated more recently, during Middle Miocene-Late Pliocene, after the closure of connection between these areas and the Indo-Pacific ocean (15 MYA). The endemic species of the Mediterranean (Raja asterias, R. radula, R. polystigma and Leucoraja melitensis) originated after the Messinian salinity crisis (7-5 MYA), when the recolonization of the basin occurred, and are still maintained in allopatric distribution by the presence of biogeographic barriers. Moreover from 4 to 2.6 MYA we can observe the formation of sister species for Raja, Leucoraja and Rajella, one of which has a Northern distribution, and the other has a Southern distribution (R. clavata vs R. straeleni, L. wallacei vs L. naevus, R. fyllae vs R. caudaspinosa and R. kukujevi vs R. leopardus + R. barnardi). The Quaternary and present oceanographic discontinuities that occur along the western African continental shelf (e.g., Cape Blanc and the Angola–Benguela Front) might contribute to the maintenance of low or null levels of gene flow between these closely related siblings species. Also sympatric speciation must be invoked to explain the evolution of skates, for example for the division between R. leopardus and R. barnardi. The speciation processes followed a south-to-north pathways for Dipturus and a north-to-south pathways for Raja, Leucoraja and Rajella underling that the evolution of the genera occurred independently. In the end, it is conceivable that the evolutionary pathways of the tribes followed the costal line during the gondwana fragmentation. The results demonstrate that the evolution of this family is characterized by a series of parallel and independent speciation events, strictly correlated to the tectonic movement of continental masses and paleogeographic and paleoclimatic events and so can be explained by a panbiogeographical (vicariance) model.

Roller, Brustbild

Signatur des Originals: S 36/F06037

Age and growth parameters of skates of the genus Bathyraja obtained between 2003-2005 along the Argentine continental shelf

In the last 20 years directed shark and ray fishery has increased alarmingly everywhere in the world. For most species though, no data on growth rate, mortality, fecundity and other life history aspects exist as of now and management of the fishery is therefore insufficient. Also there still exist methodological difficulties in the age determination of elasmobranchs fishes, a fact which complicates the investigation of growth parameters. This study tried to identify the best ageing methods and estimate growth parameters for ten skate species of the genus Bathyraja, all occurring in the southwest Atlantic in depths of 50m and more. 720 samples were collected on board of argentine research vessels in between 2003 and 2005. Crystal violet and a new staining method using potassium permanganate, both applied on sagittal sections of vertebral centra, proved to be most effective in enhancing the banding pattern in most of the species. Thorns were also tested and readings were consistent with the ones made on vertebral sections. Growth parameters could be derived for six species and for the other four estimates could be made. Growth rate as well as infinite length varied between species, with those attaining bigger sizes having lower growth rates. No latitudinal differences in growth rate could be detected but a comparison with samples from other studies showed that total lengths were always reported to be higher around the Malvinas Islands.

Full-Wafer Roller-NIL Processes for Silicon Solar Cell Texturisation

The highest solar cell efficiencies both for c-Si and mc-Si were reached using template based texturing processes. Especially for mc-Si the benefit of a defined texture, the so called honeycomb texture, was demonstrated impressively. However, up until now, no industrially feasible process has been available to pattern the necessary etching masks with the sufficient resolution. Roller-Nanoimprint Lithography (Roller-NIL) has the potential to overcome these limitations and to allow high quality pattern transfers, even in the sub-micron regime, in continuous in-line processes. Therefore, this etch-mask patterning technique is a suitable solution to bring such elaborate features like the honeycomb texture to an industrial realization. Beyond that, this fast printing-like technology opens up new possibilities to introduce promising concepts like photonic structures into solar cells.

The anthropometric profile of elite roller figure skaters

Although the anthropometric profiles of Olympic athletes, as a group, are well known, there is still a need for specific reference data for each sport given that each discipline has its own characteristics. This study has been designed considering the limited number of articles that focus on the anthropometric characteristics of artistic roller skating and, more specifically, the figures discipline. The aim of this study is twofold: firstly, to define the anthropometric profile, body composition and somatotype of male and female artistic roller figure skaters in order to establish specific profiles; and, secondly, to establish the differences between the anthropometric profiles, body compositions and somatotypes of male and female skaters. Twenty-nine professional roller skaters (male = 15, female = 14) underwent measurements of standard anthropometry (height, body mass, arm span, 8 skinfolds, 3 breadths and 11 girths). The somatotype was measured using the Heath-Carter methods. A T-Student test for independent samples was conducted in order to assess the differences between male and female skaters. Significant statistical differences were found between male and female skaters in terms of body mass, height, arm span, the sum of four and six skinfolds and all skinfold measurements. Male skaters have a BMI of 21.4± 1.6 and female skaters have a BMI of 21.5 ± 2.4. The results indicate that arm span is an important characteristic for skaters. Mesomorphy is the most important component, followed by endomorphy, for male and female skaters. Male skaters have an endomesomorphic somatotype (3.5-4.5-2.5) and female skaters have a balanced mesomorphic somatotype (3.3-4.1-2.9).