π-Selective stationary phases: (III) Influence of the propyl phenyl ligand density on the aromatic and methylene selectivity of aromatic compounds in reversed phase liquid chromatography

The retention characteristics of phenyl type stationary phases for reversed phase high performance liquid chromatography are still largely unknown. This paper explores the retention process of these types of stationary phases by examining the retention behaviour of linear PAHs and n-alkylbenzenes on a series of propyl phenyl stationary phases that have changes in their ligand density (1.23, 1.31, 1.97, 2.50 μmol m⁻²). The aromatic and methylene selectivities increased with increasing ligand density until a point where a plateau was observed, overall the propyl phenyl phases had a higher degree of aromatic selectivity than methylene selectivity indicating that these columns are suitable for separations involving aromatic compounds. Also, retention characteristics relating to the size of the solute molecule were observed to be influenced by the ligand density. It is likely that the changing retention characteristics are caused by the different topologies of the stationary phases at different ligand densities. At high ligand densities, the partition coefficient became constant.

Characterisation and application of a bovine U6 promoter for expression of short hairpin RNAs

Background
The use of small interfering RNA (siRNA) molecules in animals to achieve double-stranded RNA-mediated interference (RNAi) has recently emerged as a powerful method of sequence-specific gene knockdown. As DNA-based expression of short hairpin RNA (shRNA) for RNAi may offer some advantages over chemical and in vitro synthesised siRNA, a number of vectors for expression of shRNA have been developed. These often feature polymerase III (pol. III) promoters of either mouse or human origin.
Results
To develop a shRNA expression vector specifically for bovine RNAi applications, we identified and characterised a novel bovine U6 small nuclear RNA (snRNA) promoter from bovine sequence data. This promoter is the putative bovine homologue of the human U6-8 snRNA promoter, and features a number of functional sequence elements that are characteristic of these types of pol. III promoters. A PCR based cloning strategy was used to incorporate this promoter sequence into plasmid vectors along with shRNA sequences for RNAi. The promoter was then used to express shRNAs, which resulted in the efficient knockdown of an exogenous reporter gene and an endogenous bovine gene.
Conclusion
We have mined data from the bovine genome sequencing project to identify a functional bovine U6 promoter and used the promoter sequence to construct a shRNA expression vector. The use of this native bovine promoter in shRNA expression is an important component of our future development of RNAi therapeutic and transgenic applications in bovine species.

Wastewater irrigation: the state of play

As demand for fresh water intensifies, wastewater is frequently being seen as a valuable resource. Furthermore, wise reuse of wastewater alleviates concerns attendant with its discharge to the environment. Globally, around 20 million ha of land are irrigated with wastewater, and this is likely to increase markedly during the next few decades as water stress intensifies. In 1995, around 2.3 billion people lived in water-stressed river basins and this could increase to 3.5 billion by 2025. We review the current status of wastewater irrigation by providing an overview of the extent of the practice throughout the world and through synthesizing the current understanding of factors influencing sustainable wastewater irrigation. A theme that emerges is that wastewater irrigation is not only more common in water-stressed regions such as the Near East, but the rationale for the practice also tends to differ between the developing and developed worlds. In developing nations, the prime drivers are livelihood dependence and food security, whereas environmental agendas appear to hold greater sway in the developed world. The following were identified as areas requiring greater understanding for the long-term sustainability of wastewater irrigation: (i) accumulation of bioavailable forms of heavy metals in soils, (ii) environmental fate of organics in wastewater-irrigated soils, (iii) influence of reuse schemes on catchment hydrology, including transport of salt loads, (iv) risk models for helminth infections (pertinent to developing nations), (v) microbiological contamination risks for aquifers and surface waters, (vi) transfer efficiencies of chemical contaminants from soil to plants, (vii) health effects of chronic exposure to chemical contaminants, and (viii) strategies for engaging the public.

Reforming Australian public sector accounting : an episode of institutional thinking

In recent years in Australia, accounting reforms have been developed which have resulted in the application of commercial systems of accounting to diverse public sector organisations. The reforms, which include the requirement to recognise infrastructure and heritage resources as assets in financial reports, endorse financial notions of accountability and performance that have been traditionally applied within private sector, profit-seeking organisations. Such notions are applied to a range of public sector organisations for the first time, even though the primary missions or objectives of many of these organisations are social, rather than financial in orientation. This critical, interpretative case study, set within the context of not-for-profit public museums, seeks to enhance an understanding of public sector accounting change based on these unique social organisations. The study examines three aspects of the reforms, namely, their development, their promotion and their defence. This examination is undertaken using the ideas contained in Mary Douglas’ (1986) How Institutions Think as the key theoretical construct. The supplementary perspectives of problematisation and epistemic communities are used to assist in applying the primary theoretical construct by explaining how, and by whom, these reforms were advocated and implemented in this specific instance. The study shows how the interpretation and application of the statements comprising the conceptual framework have shaped the development, promotion and defence of detailed standards developed for specific public sector organisations. In doing so, the study addresses two key research questions: (1) How were financial notions of accountability and performance of Australian public sector organisations constructed during the period 1976-2001 and articulated in the CF, once its development began, within this reform period? (2) How were these notions and other concepts of financial reporting outlined in the CF interpreted and applied in the (i) development; (ii) promotion; and (iii) defence of detailed accounting standards for not-for-profit public museums in Australia during the period under investigation? The study demonstrates that the concepts of financial reporting outlined in the conceptual framework were used by a relatively small group of technical experts located in influential positions in accounting regulation and in other fields to justify the application of accrual accounting within diverse public sector organisations. During the period examined, only certain questions were posed and certain issues considered and many problems associated with the implementation of the reforms were not considered. Accordingly, a key finding of the study is that each aspect of the reform period was guided and constrained by institutional thinking. In addition, the study shows how the framework's content can be used to permit equally well-argued, but conflicting, accounting policies to be adopted and defended for the same items, indicating the framework to be of only limited value as a technical tool. This leads to another key finding of the study, namely, that the framework is best understood as a political tool, serving a crucial role in enabling accrual accounting reforms to be developed, promoted and defended within the public sector. Thus, the study seeks to offer an enhanced understanding of the nature and determinants of accounting change, and accordingly, it broadens an understanding of the use of the conceptual framework, as an institution, in developing, promoting and defending changes to accounting practice.

Investigation of the intersection of constraints model of motion perception

The direction and speed of motion of a one-dimensional (1-D) stimulus, such as a grating, presented within a circular aperture is ambiguous. This ambiguity, referred to as the Aperture Problem (Fennema & Thompson, 1979) results from (i) the inability to detect motion parallel to grating orientation, and (ii) the occlusion of border information, such as the ‘ends’ of the grating, by the surface forming the aperture, Adelson and Movshon's (1982) intcrsection-of-constraints (IOC) model of motion perception describes a two-stage method of disambiguating the motion of 1-D moving stimuli (e.g., gratings) to produce unambiguous motion of two-dimensional (2-D) objects (e.g., plaid patterns) made up of several 1-D components. Specifically, in the IOC model ambiguous 1-D motions extracted by Stage 1 component-selective mechanisms are integrated by Stage 2 pattern-selective mechanisms to produce unambiguous 2-D motion signals. ‘Integration’ in the context of the IOC model involves determining the single motion vector (i.e., combination of direction and speed) which is consistent with the I-D components of a 2-D object. Since the IOC model assumes that 2-D objects undergo pure translation (i.e., without distortion, rotation, etc.), the motion vector consistent with all 1-D components describes the motion of the 2-D object itself. Adelson and Movshon (1982) propose that neural implementation of the computation underlying the IOC model is reflected in the perception of coherent 2-D plaid motion reported when two separately-moving ‘component’ gratings are superimposed. Using these plaid patterns the present thesis assesses the IOC model in terms of its ability to account for the perception of 2-D motion in a variety of circumstances. In the first series of experiments it is argued that the unambiguous motion perceived for a single grating presented within a rectangular aperture (i.e., the Barberpole illusion; Wallach, 1976) reflects application of the IOC computation to the moving 1-D grating and the stationary boundary of the aperture. While contrary to the assumption which underlies the IOC model (viz., that integration occurs between moving 1-D stimuli), evidence consistent with the involvement of the IOC computation in mediating the Barberpole illusion (in which there is only one moving stimulus) is obtained by measuring plaid coherence as a function of aperture shape. It is found that rectangular apertures which bias perceived component motions in directions consistent with plaid direction facilitate plaid coherence, while rectangular apertures which bias perceived component motions in directions inconsistent with plaid direction disrupt plaid coherence. In the second series of experiments, perceived directions of motion of type I symmetrical, type I asymmetrical, and type II plaids are measured with the aim of investigating the deviations in plaid directions reported by Ferrera and Wilson (1990) and Yo and Wilson (1992). Perceived directions of both asymmetrical and type II plaids are shown to deviate away from lOC-predicted directions and towards mean component direction. Furthermore, the magnitude of these deviations is being proportional to the difference between lOC-predicted plaid direction and mean component direction. On the basis of these directional deviations, modification to the IOC model is proposed. In the modified IOC model it is argued that plaid perception involves (i) the activity of Stage 2 pattern-selective mechanisms (and the Stage 1 component-selective mechanisms which input into these pattern-selective mechanisms) involved in implementing the IOC computation, and (ii) component-selective mechanisms which influence plaid perception directly, and ‘extraneously’ to the IOC computation. In the third series of experiments the validity of this modified IOC model, as well as the validity of alternative one-stage models of plaid perception are assessed in relation to perceived directions of plaid-induced MAEs as a function of both plaid direction and mean component direction. It is found that plaid-induced MAEs are shifted away from directions opposite to lOC-predicted plaid direction towards the direction opposite to mean component direction. This pattern of results is taken to be consistent with the modified IOC model which predicts the activity, and adaptation both of mechanisms signalling plaid direction (via implementation of the IOC computation), and ‘extraneous-type’ component-selective mechanisms signalling component directions. Alternative one-stage models which predict the adaptation of only mechanisms signalling plaid direction (the feature-tracking model), or the adaptation only of mechanisms signalling component directions (the distribution-of-activity model), cannot account for the directions of plaid-induced MAEs reported. The ability of the modified IOC model to account for the perceived directions of (i) gratings in rectangular apertures, (ii) various types of plaid in circular apertures, and (iii) directions of plaid-induced MAEs, is interpreted as supporting the proposition that human motion perception is based on a parallel and distributed process involving Stage 2 pattern-selective mechanisms (and the Stage 1 component-selective mechanisms which input into these mechanisms) taken to implement the IOC computation, and component-selective mechanisms taken to provide an 'extraneous' direct contribution to motion perception.

Status of tailings dumps : let D5s go working in the past?

It was decided in the De Beers v Ataqua Mining (Pty) Ltd that ''tailings dumps'' created by mining companies before the Mineral and Petroleum Resources Development Act, 28 of 2002 ("the MPRDA") came into operation are not governed by its provisions because such dumps are not "residue stockpiles" or "residue deposits" for purposes of the MPRDA. Ownership of tailings dumps is determined by the common law principles of accession. Ownership of a movable dump has to be transferred by one of the recognised forms of delivery of movables. Processing of these dumps will, however, still be subject to compliance with South African environmental, health and safety laws in general. It is submitted that mine dumps or tailings dumps created upon the exercise of "old order mining rights" before the commencement of the MPRDA and even after commencement of the MPRDA until eventual termination of the "old order mining rights" are not subject to the extensive, mining, environmental, empowerment provisions of the MPRDA. Termination of "old order mining rights" takes place upon: (i) refusal of an application for conversion of a mining right during (or even after) the period of transition, (ii) conversion into and registration of new order mining rights during (or even after) the period of transition or (iii) termination of unconverted "old order mining rights" on 30 April 2009. To the extent that this decision has made it possible to embark on a shorter and less cumbersome route in the reprocessing and eventual disappearance of most tailings dumps, it is to be welcomed from an economical, environmental, job creation and aesthetic perspective. Proposed amendments to the MPRDA to undo the impact of the De Beers decision should be carefully considered against these mentioned benefits and a possible finding that it may amount to an expropriation without compensation.