Comparison of the population growth potential of South African loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles

A beach conservation programme protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles in South Africa was started in 1963. As initial numbers of nesting females were low for both species (107 loggerheads and 24 leatherbacks) it was proposed that the protection of eggs, hatchlings and nesting females along the nesting beach would induce population growth and prohibit local extinction. Today, 50 years later, the loggerhead population exceeds 650 females per annum, whereas the leatherback population counts about 65 nesting females per year. The trend for leatherback turtles is that the population has been stable for about 30 years whereas loggerheads are increasing exponentially. Thus, this thesis investigated several life-history traits to explain the differing responses to the ongoing beach conservation programme. Reproductive output and success were assessed for both species; it was hypothesised that environmental conditions are sub-optimal for leatherback turtles to reproduce successfully. It was ascertained that nesting loggerhead females deposit larger clutches than leatherbacks (112 ± SD 20 eggs and 100 ± SD 23 eggs, respectively), but that annual reproductive output per individual leatherback female exceeds that of loggerhead turtles (±700 eggs and ±448 eggs, respectively) because they exhibit a higher intra-seasonal nesting frequency (leatherbacks n = 7 and loggerheads n = 4 from Nel et al. 2013). Emergence success (i.e. the percentage of hatchlings produced) per nest was similar for both species (loggerhead 73.6 ± SD 27.68 % and leatherback turtles 73.8 ± SD 22.70 %), but as loggerhead turtles nest in greater numbers, i.e. producing more hatchlings per year, the absolute population growth potential favours the loggerhead turtle. The second factor investigated was sex ratio because sea turtles display temperature-dependent sex determination (TSD) where extreme incubation temperatures can skew the sex ratio (i.e. feminising or masculinising a clutch). It was suspected that leatherback turtles are male-biased as this is the southern-most rookery (for both species). Further, leatherback nests are generally closer to the high tide mark, which might induce a cooling effect. Standard histological techniques were applied to sex hatchlings and a generalized linear model (GLM) was used to approximate annual sex ratio. Loggerhead sex ratio (2009 - 2011) was estimated at 86.9 ± SE 0.35 % female-biased; however, sufficient replication for the leatherback population was only obtained for season 2010, which indicated a 97.1 % (95 % CI 93.3 - 98.7) female bias. Both species are, thus, highly female-biased, and current sex ratio for leatherback turtles is not prohibiting population growth. Current sex ratios, however, are not necessarily indicative of sex ratios in the past which would have induced present population growth. Thus, to account for present population growth profiles, sex ratios from the past needed to be ascertained. Annual sex ratios (1997 - 2011) were modelled from historical air and sea surface temperatures (SSTs) but no significant change over time was obtained for either loggerhead or leatherback turtles (linear regression; p ≥ 0.45). The average sex ratio over this 15-year period for the South African loggerhead turtle was approximated at 77.1 ± SE 3.36 % female-biased, whereas leatherbacks exhibited a 99.5 ± SE 0.24 % female bias. Re-analysing data from the mid-80s by Maxwell et al. (1988) also indicated a 77.4 % female bias for the South African loggerhead population. It is, therefore, highly likely that sex ratios of the South African loggerhead and leatherback sea turtle populations have been stable for at least three decades and are not accountable for the differing population growth profiles as they are displayed today. Another possibility that could explain the opposed population growth profiles is the time taken for animals to replace themselves, i.e. age at maturity. It was suspected that age at maturity for the South African loggerhead turtle is comparable with that for leatherbacks. Using data from a 30-year mutilation tagging experiment (i.e. notching), age at first reproduction for South African loggerhead females was estimated. Results ranged broadly but a mean of 36.2 ± SD 7.71 years was obtained using a Gaussian distribution. Age at reproduction of the South African leatherback turtle was not determined but the literature suggests a much younger age of 13.3 - 26.8 years (Zug & Parham 1996, Dutton et al. 2005, Avens et al. 2009, Jones et al. 2011). Therefore, population growth would favour leatherback turtles as they exhibit a much shorter generation time. Finally, it was concluded that all life-history parameters investigated favour leatherback turtles, yet loggerheads are displaying population growth. However, as there were no obvious constraints to population growth on the nesting beach, it is suspected that population growth of the South African leatherback turtle is either unobserved (due to inadequate monitoring not capturing sufficient numbers of nesting events to establish a trend) or that population growth is prohibited by some offshore factor such as industrial fisheries (or some other driver not yet identified). Monitoring should, thus, be expanded and offshore mortality monitored as the leatherback population nesting in South Africa is still critically endangered with nesting numbers dangerously low

Collision-induced secondary electron and negative ion emission from metallic surfaces

Absolute yields of negative ions and secondary electrons resulting from collisions of positive sodium ions (Na{dollar}\sp{lcub}+{rcub}){dollar} with polycrystalline aluminum (Al) and molybdenum (Mo) surfaces and the Mo (100) surface have been measured as a function of the oxygen (O) coverage, from none up to several monolayers, for impact energies, E {dollar}\u3c{dollar} 500 eV. Negative oxygen ions (O{dollar}\sp{lcub}-{rcub}){dollar} are found to be the dominant sputtered negative ions and for the three surfaces at all O coverages and Na{dollar}\sp{lcub}+{rcub}{dollar} impact energies. The O{dollar}\sp{lcub}-{rcub}{dollar} and secondary electron yields share a common impact energy threshold at {dollar}\rm E\sb{lcub}th{rcub}\approx 50{dollar} eV, and both have a strong dependence on the oxygen coverage of the surface.;The kinetic energy distributions of the secondary electrons and sputtered O{dollar}\sp{lcub}-{rcub}{dollar} were determined as functions of O coverages and impact energies. The O{dollar}\sp{lcub}-{rcub}{dollar} distributions are characterized by a narrow, low energy peak (at {dollar}\sim{dollar}1-2 eV) followed by a low level, high energy tail. The secondary electrons have a narrow (FWHM {dollar}\sim{dollar} 1-2 eV) kinetic energy distribution, centered essentially at the same most probable kinetic energy as the ions. The shapes of the respective distributions and the most probable kinetic energies are essentially invariant with the impact energy, O coverage and the metal surface.;The results were analyzed in terms of conventional collision cascade model, but the calculation could not be fitted to the experimental results. An electronic excitation mechanism is proposed to augment the collision cascade and to provide a mechanism for secondary electron emission. In the model, adsorbed O, which resides on the surface essentially as O{dollar}\sp{lcub}-{rcub},{dollar} is collisionally excited into an (MO{dollar}\sp{lcub}-{rcub})\sp*{dollar} repulsive state, and as the O{dollar}\sp{lcub}-{rcub}{dollar} exits the surface along the surface potential energy curve, it can decay by emission of an electron to the metal or to the vacuum, or it can survive as an ion. The parameters of this model can be adjusted such that the calculated kinetic energy distribution, together with that of the collision cascade, can reasonably reproduce the experimental observations for the ions and provide a reasonable fit to the corresponding electron kinetic energy distributions as well

Algorithms for Skidding Distance Modelling on a Raster Digital Terrain Model

Algorithms for determining skyline skidding and tractor skidding distances on raster digital terrain models are introduced and presented. Modules named DOWN, UP, STRDOWN, STRUP were programmed in Turbo Basic language to work with a raster Digital Terrain Model. The DTM, interpolated from a set of digitized contours, and all other data were handled in the IDRISI GIS environment. Implications of these algorithms are discussed, especially their advantages and disadvantages relative to the opening of forests, and more broadly forest operational planning. Flowcharts illustrating the method for calculating tractor and skyline skidding distance are included

The Czech Economic Elite after Fifteen Years of Post-Socialist Transformation

The East-Central European post-socialist transformations have now reached a new stage, with the need to address the problems of further modernisation & maintenance in the context of the EU. The role of elites in this process is as intermediators between the influence of the European context & the needs & interests of differentiated internal social structures. Their attitudes & behaviour exhibit a high degree of internal fragmentation & division corresponding to various strategical orientations favouring various societal models. The post-socialist Czech economic elite was initially reproduced out of former state socialist managers & their cadre reserves. After the first phase of economic developments, inspired by neo-liberal radical privatisation & elements of 'shock therapy', & once the new, more European phase ushered in many new factors, there was a distinct decline in the number of 'old-new' economic elite on the scene. In the empirical part of the article the results of several surveys are used to briefly describe the changes in the composition of the Czech economic elite in the 1994-2005 period & to summarise their attitudes & behaviour. The analysis concludes that the current image of a liberal & pro-European Czech elite is consistent with the stable & remarkable progress of the Czech economy since 1999, the considerable wealth, strong profits, & high salaries enjoyed by top elites, & the enhancement of their role in the European economy. There are also some limitations & weak points that diverge from this general picture. The article's conclusions touch on the question of the role of the economic elite in the progress of arriving at more consensual attitudes & behaviour among societal elites as a whole, favouring further economic growth, modernisation & the strengthening of social cohesion in the context of the EU

Density-Based Topology Optimization in Method of Moments: Q-factor Minimization

Classical gradient-based density topology optimization is adapted for method-of-moments numerical modeling to design a conductor-based system attaining the minimal antenna Q-factor evaluated via an energy stored operator. Standard topology optimization features are discussed, e.g., the interpolation scheme and density and projection filtering. The performance of the proposed technique is demonstrated in a few examples in terms of the realized Q-factor values and necessary computational time to obtain a design. The optimized designs are compared to the fundamental bound and well-known empirical structures. The presented framework can provide a completely novel design, as presented in the second example.Comment: 13 pages, 13 figure

Verbesserung der Richtungsstabilisierung von inertial gesteuerten astronomischen Flugzeugteleskopen am Beispiel von SOFIA

Diese Arbeit beschreibt die Verbesserung der Richtungsstabilisierung des Flugzeugteleskops SOFIA. Das Ziel des Flugzeugteleskops SOFIA sind astronomische Beobachtungen im Infrarotbereich. Da der Wasserdampf der Erdatmosphäre den Großteil der Infrarotstrahlung absorbiert, sind solche Beobachtungen mit herkömmlichen Teleskopen von der Erdoberfläche aus kaum möglich. Um unerwünschte Drehbewegungen des Flugzeugteleskops, z.B. hervorgerufen durch Luftturbulenzen, auszugleichen, ist zuerst eine genaue Messung bzw. Schätzung derselben notwendig. Diese Informationen werden dann mittels Computer in Echtzeit weiterverarbeitet. Anschließend sorgen dann Motoren dafür, das Teleskop wieder in die gewünschte Lage zu drehen. Die Motoren können das Teleskop nur so genau ausrichten, wie es die Genauigkeit des Meßsystems zuläßt. Die Messung der Drehbewegungen geschieht mit drei zueinander senkrecht angeordneten Gyroskopen. Diese weisen jedoch Fehler auf, so daß sich die Ausrichtgenauigkeit verschlechtert. Deshalb werden mit Hilfe einer auf das Teleskop montierten Kamera in regelmäßigen Zeitabständen Bilder des Sternhimmels aufgenommen. Aus diesen Bildern wird dann mit Hilfe der dort sichtbaren Sterne die aktuelle Orientierung des Teleskops bestimmt. Mittels dieser Orientierung werden dann die Fehler der Gyroskope korrigiert und der lineare Fehleranteil für die Zukunft extrapoliert. Dieser Fehler wird dann schon im Voraus vom Teleskoplageregler berücksichtigt. Dadurch wird der quasikonstante Fehleranteil minimiert. Je besser dieser Fehler geschätzt wird, desto geringer ist die Drift des Teleskops um seine Achsen. Dadurch erhöht sich die Richtungsstabilisierung ...thesi

Development of M5 Cladding Material Correlations in the TRANSURANUS Code: Revision 1

The technical report is based on an earlier research on material properties of the M5 structural material. Complementing this research with new M5 data found in open literature, a set of correlations has been developed for the implementation to the TRANSURANUS code. This includes thermal, mechanical, and chemical (corrosion) properties of M5. As an example, thermal capacity or burst stress correlations have been proposed using the available experimental data. The open literature provides a wide range of experimental data on M5, but for some quantities they are not complete enough to be suitable for the implementation to the TRANSURANUS code. A balanced consideration of similarity of M5 characteristics to those of Zircaloy-4 (Zry-4) or E110 have therefore led to the recommendation to use some of these data selectively also for M5. As such, creep anisotropy coefficients of E110 are recommended to be used also for M5.JRC.G.I.4-Nuclear Reactor Safety and Emergency Preparednes

A new evaluation method of local muscular load at workplaces in Czech companies

In this article, the role and position of Ergonomics, Local Muscular Load Measuring, wас defined. There are two main parts of ergonomics: overall physical load and local muscle load. The measurement methods based on using muscle forces are used in the Czech Republic mainly. Other countries measure local muscular load more subjectively, through evaluation sheets (ergonomic checklists). However, in this article, the presented methods are more precise and objective. Otherwise, the employee risks exposure to occupational diseases, serious illnesses, etc. In this case, the employer is then exposed to liabilities stemming from not creating suitable working conditions, such as compensation, increased recruitment costs, etc. In the Czech Republic, management is increasingly being held liable for occupational diseases stemming from “local muscular load” of employees. In the world, it is also known as the repetitive strain injury (RSI). As a result, it is necessary to evaluate the local muscular load in Czech businesses and identify the main causes of overload. In this article, the authors will introduce a new methodology for local muscular load measuring with the datalogger equipment. The research also showed that the health and safety limits for local muscular load were exceeded in 52% of the workplaces researched. Various causes and weaknesses were identified. These could increase those risks

Using Texture Synthesis for Non-Photorealistic Shading from Paint Samples

This paper presents several methods for shading meshes from scanned paint samples that represent dark to light transitions. Our techniques emphasize artistic control of brush stroke texture and color. We first demonstrate how the texture of the paint sample can be separated from its color gradient. We demonstrate three methods, two real-time and one off-line for producing rendered, shaded images from the texture samples. All three techniques use texture synthesis to generate additional paint samples. Finally, we develop metrics for evaluating how well each method achieves our goal in terms of texture similarity, shading correctness and temporal coherence