Methodology in the recording of rock paintings

Daar bestaan 'n groeiende belangstelling in die belangrike rol wat San-rotsskilderinge speel in ons nasionale erfenis. Hierdie belangstelling het gelei tot 'n besef van die vinnige agteruitgang van hierdie werke, as gevolg van natuurlike en mensllke oorsake en dus van die dringendheid van effektiewe konservasie. Kopiering - deur middel van natreksels of foto's - is tans die enigste metode om die werke te bewaar, sodat 'n getroue rekord beskikbaar kan wees vir toekomstige navorsers. 'n Voorbeeld van die waarde hiervan is gelee in die pionierswerk van William Stow. Vele van die skilderinge wat hy so versigtig gekopieer het in die laat 18OO's het intussen verdwyn of tot so 'n mate vervaag dat hul nouliks sigbaar is. Hierdie artikel beskryf in besonderhede die tegnieke van natrekwerk en fotografie wat oor 'n periode van dertig jaar geleer is deur terreinondervinding. Die doel van hierdie beskrywing is om die entoesias aan te moedig, om 'n sin vir dringendheid te bevorder en om frustrerende foute te help voorkom.There is a growing awareness of the significant part San rock paintings play in our national heritage. This has led to a realisation that they are fast deteriorating due to natural and human causes and that there is now an urgent need to take effective action for their preservation. The only method of preservation available to us at present is that of copying - either by tracing or photography - so that a faithful record is available for future researchers. An example of the value of this is the pioneering work done by William Stow. Many of the paintings he so painstakingly copied in the late 1800's have either disappeared completely or are so faded as to be nearly invisible. This article describes in detail the tracing and photographic techniques, learned from thirty years of field experience. The aim of this description is to encourage the enthusiast, to foster a sense of urgency with regard to preservation and to help avoid frustrating errors.Article digitised using: Suprascan 1000 RGB scanner, scanned at 400 dpi; 24-bit colour; 100% Image derivating - Software used: Adobe Photoshop CS3 - Image levels, crop, deskew Abbyy Fine Reader No.9 - Image manipulation + OCR Adobe Acrobat 9 (PDF

Effect of Diet Complexity and the Additive Effect of Pharmacological Levels of ZnO and Carbadox on the Performance of Weaned Pigs

The scientific literature documents the efficacy of antibacterial feed additives for weaned pigs. More recently, Feeding therapeutic levels of supplemental zinc (Zn) from zinc oxide (ZnO) stimulated voluntary feed intake and weight gain of young pigs. Over the last decade, research demonstrated that swine diets contianing sub-therapeutic levels of various antibiotics combined with pharmacological levels of copper (Cu) resulted in better performance than when either ingredient was provided individually. In 1982, an additive improvement in performance was found when a sub-therapeutic level (55 mg/kg) of carbodox (CARB) and high level of Cu (125 mg/kg) were provided in combination in a corn-soybean meal diet. The interactive effects of Cu from copper sulfate (CuSO4) and Zn from ZnO in diets for weanling pigs on performance have been evaluated, and the use of 3000 mg/kg Zn alone provided greater performance than the use of both Cu and Zn. Because Cu and Zn have independent biological growth promoting properies, it is necessary to determine if swine diets containing an antimicrobial agent in combination with 3000 mg/kg Zn as ZnO may result in better performance than when either is provided individually. The objectives of this study were (1) to determine the additive effects of 3000 mg/kg Zn as ZnO and CARB on weaned pig performance and (2) to evaluate whether simple nursery diets containing Zn as ZnO support performance that is similar to complex (phase I and phase II) nursery diets

Effect of Diet Complexity on the Performance of Newly Weaned Pigs Fed Pharmacological Levels of Zinc Oxide

Zinc (Zn) is an essential trace mineral for swine. The requirement for Zn has been suggested to be in the range of 50 to 100 mg/kg for pigs at various stages of growth. The bioavilability of zinc oxide (ZnO) as a source of Zn is lower than other Zn sources such as zinc sulfate (ZnSO4), zinc carbonate (ZnCO3) and Znmethionine in weanling pigs. Recent studies have shown that adding pharmacological levels (2000-4000 mg/kg) of Zn as ZnO to corn-soybean meal based diets improved started pig performance and was effective in controlling E. coli scours for weanling pigs. Very high levels of Zn can be toxic. Studies have demonstrated that Zn toxicosis is not found or is much less severe when ZnO is supplemented in corn-soybean meal dies for weanling pigs than ZnCO3 is the source of pharmacological levels of Zn. The response for weaned pigs to the addition of pharacological levels of ZnO to simple diets containing corn, soybean meal, and dried-whey has not been compared to the addition of the same levels of Zn to complex diets containing these same ingredients plus animal protein supplements. The objective of this study was to determine whether diet composition affected the growth promoting properties of ZnO in weaned pig diets

Light Scattering on Nanowire Antennas: A Semi-Analytical Approach

Two semi-analytical approaches to solve the problem of light scattering on nanowire antennas are developed and compared. The derivation is based on the exact solution of the plane wave scattering problem in case of an infinite cylinder. The original three-dimensional problem is reduced in two alternative ways to a simple one-dimensional integral equation, which can be solved numerically by a method of moments approach. Scattering cross sections of gold nanowire antennas with different lengths and aspect ratios are analysed for the optical and near-infrared spectral range. Comparison of the proposed semi-analytical methods with the numerically rigorous discrete dipole approximation method demonstrates good agreement as well as superior numerical performance.Comment: 9 pages, 5 figure

Experimental Control and Characterization of Autophagy in Drosophila

Insects such as the fruit fly Drosophila melanogaster, which fundamentally reorganize their body plan during metamorphosis, make extensive use of autophagy for their normal development and physiology. In the fruit fly, the hepatic/adipose organ known as the fat body accumulates nutrient stores during the larval feeding stage. Upon entering metamorphosis, as well as in response to starvation, these nutrients are mobilized through a massive induction of autophagy, providing support to other tissues and organs during periods of nutrient deprivation. High levels of autophagy are also observed in larval tissues destined for elimination, such as the salivary glands and larval gut. Drosophila is emerging as an important system for studying the functions and regulation of autophagy in an in vivo setting. In this chapter we describe reagents and methods for monitoring autophagy in Drosophila, focusing on the larval fat body. We also describe methods for experimentally activating and inhibiting autophagy in this system and discuss the potential for genetic analysis in Drosophila to identify novel genes involved in autophagy

Levitation of quantum Hall critical states in a lattice model with spatially correlated disorder

The fate of the current carrying states of a quantum Hall system is considered in the situation when the disorder strength is increased and the transition from the quantum Hall liquid to the Hall insulator takes place. We investigate a two-dimensional lattice model with spatially correlated disorder potentials and calculate the density of states and the localization length either by using a recursive Green function method or by direct diagonalization in connection with the procedure of level statistics. From the knowledge of the energy and disorder dependence of the localization length and the density of states (DOS) of the corresponding Landau bands, the movement of the current carrying states in the disorder--energy and disorder--filling-factor plane can be traced by tuning the disorder strength. We show results for all sub-bands, particularly the traces of the Chern and anti-Chern states as well as the peak positions of the DOS. For small disorder strength $W$ we recover the well known weak levitation of the critical states, but we also reveal, for larger $W$, the strong levitation of these states across the Landau gaps without merging. We find the behavior to be similar for exponentially, Gaussian, and Lorentzian correlated disorder potentials. Our study resolves the discrepancies of previously published work in demonstrating the conflicting results to be only special cases of a general lattice model with spatially correlated disorder potentials. To test whether the mixing between consecutive Landau bands is the origin of the observed floating, we truncate the Hilbert space of our model Hamiltonian and calculate the behavior of the current carrying states under these restricted conditions.Comment: 10 pages, incl. 13 figures, accepted for publication in PR

Temperature-dependent Raman spectroscopy in BaRuO3_3 systems

We investigated the temperature-dependence of the Raman spectra of a nine-layer BaRuO$_3$ single crystal and a four-layer BaRuO$_3$ epitaxial film, which show pseudogap formations in their metallic states. From the polarized and depolarized spectra, the observed phonon modes are assigned properly according to the predictions of group theory analysis. In both compounds, with decreasing temperature, while $A_{1g}$ modes show a strong hardening, $E_g$ (or $E_{2g}$) modes experience a softening or no significant shift. Their different temperature-dependent behaviors could be related to a direct Ru metal-bonding through the face-sharing of RuO$_6$. It is also observed that another $E_{2g}$ mode of the oxygen participating in the face-sharing becomes split at low temperatures in the four layer BaRuO$_3$. And, the temperature-dependence of the Raman continua between 250 $\sim$ 600 cm$^{-1}$ is strongly correlated to the square of the plasma frequency. Our observations imply that there should be a structural instability in the face-shared structure, which could be closely related to the pseudogap formation of BaRuO$_3$ systems.Comment: 8 pages, 6 figures. to be published in Phys. Rev.

A developmental and training study of children's ability to find safe routes to cross the road

The sites and routes that children of different ages considered to be safe to cross the road were investigated. In Expt 1, children aged 5, 7, 9 and 11 years were instructed to choose 'the safest' crossing sites and routes to specified destinations. The results showed a gradual developmental shift with safer, more adult-like choices appearing with increasing age. Five and 7 year olds exhibited only a rudimentary selection procedure, choosing the most direct route as safest and showing a marked lack of awareness of the dangers posed by nearby roadside obstacles or other visual restrictions. In a further experiment, 5-year-olds were individually trained in finding safe places to cross. Training took place either in the real road environment or using a tabletop model of a traffic environment. A series of pre-and post-tests enabled the effectiveness of the training to be assessed. Substantial improvements following training were obtained in both groups. No differences were found between the two training methods. Though performance fell somewhat over the two months following training, trained children still outperformed their untrained peers eight months after the programme ended. The implications for road safety education are discussed

Behavioural group training of children to find safe routes to cross the road

Young children show poor judgement when asked to select safe places to cross the road and frequently consider dangerous sites to be safe ones. Thus, a sharp bend, the brow of a hill or positions close to parked cars are considered safe places to cross by most children under 9 years of age. This study examined the effectiveness of two practical training programmes in improving the judgements of 5-year-olds. Children were trained in small groups either in the real road environment or using simulations set up on a table-top model. A series of pre-and post-tests allowed the effectiveness of training to be assessed. Significant improvements relative to controls were found in both groups following training. There were no differences between the two training methods. Improvements were robust and no deterioration was observed two months after the programme ended. However, the benefits of group training were less marked than in an earlier study in which children were trained individually. The implications for road safety education are discussed