A review of landscape rehabilitation frameworks in ecosystem engineering for mine closure

Mining causes changes to the environment and rehabilitation is necessary at mine closure. There is a lack of appropriate frameworks for mine site rehabilitation. In most cases, restoring the mine to previous conditions is challenging. Alternatively, mining companies can engineer ecosystems to suit new site conditions and aim for a self-sustaining and resilient ecosystem. In ecosystem design there should be consideration of the four key dimensions of any ecosystem; landscape, function, structure and composition (LFSC). Alcoa’s Bauxite mines and Barrick (Cowal) Limited’s Gold Mine have considered LFSC in their rehabilitation practices. From this, a framework based on LFSC is proposed as a means of planning, undertaking and monitoring mine rehabilitation, which together aim for a self-sustaining and resilient ecosystem. Elements of this framework are being utilised in the industry, and are supported by research. The framework could be used as an industry standard, utilised by regulatory bodies and potentially used in conjunction with other models and in other rehabilitation environments

The effect of tannic compounds on anaerobic wastewater treatment

Anaerobic wastewater treatment is an alternative to the conventional aerobic treatment processes for the removal of easily biodegradable organic matter in medium to high strength industrial wastestreams. Anaerobic treatment has several advantages, however one important disadvantage is the high sensitivity of the anaerobic bacteria (ie. methanogenic bacteria) to toxic compounds. The anaerobic technologies were initially developed for the treatment of non-toxic organic wastewaters. As the technology matured, the limits of its application to toxic wastewaters were studied. Past research has been mostly directed towards the toxic effects of compounds introduced by man into the industrial process rather than natural constituents present in agricultural wastewaters.This dissertation investigates the role of natural polar phenolics (ie. tannins and related compounds) on anaerobic digestion. Tannins are important constituents of certain types of agro-industrial wastewaters such as vegetable tannery effluent; olive oil mill effluent; wine vinasse; coffee pulp water; debarking wastewater; and masonite (fiber board) wastewater. A distinct feature of highly hydroxylated phenolics is that they are readily oxidized to darkly colored humic compounds. Such transformations can generate products which differ in toxicity and biodegradability compared to the original tannic compounds. Industrial process waters are often exposed to conditions which promote phenol oxidation, therefore the role of humus forming processes was a major consideration included in this study.The toxicity of tannin compounds to anaerobic bacteria was determined. The concentration of tannins found to cause 50% inhibition to methanogenic bacteria was 350 and 700 mg L -1of condensed and hydrolyzable tannins, respectively. The condensed tannins were the major inhibitors present in wastewater derived from the debarking of wood at pulping factories.The effects of oxidation treatments on the methanogenic toxicity of phenolic compounds was evaluated. The initial polymerization of monomers led to a higher toxicity due to an increase in tannic qualities. The oligomers formed have stronger hydrogen bonds with proteins than the monomers. They are thus more likely to react with the functional proteins of bacteria. If the polymerization was continued, a decrease in toxicity occurred due to a lower effectiveness of high MW compounds to penetrate bacteria.These results indicated that toxic oligomeric tannins can be detoxified by oxidative polymerization. The application of autoxidation (aeration at a high pH) as a pretreatment prior to anaerobic digestion of tannin containing wastewater was tested. Debarking wastewaters of coniferous trees were successfully detoxified by autoxidation pretreatments. The tannins were converted to poorly degradable humic compounds that were non-toxic. During anaerobic treatment, no inhibition occurred and the fermentable fraction of the wastewater was converted to methane. The high MW humic products were non-toxic for aquatic organisms and thus could be discharged to the surface waters with considerably less environmental impact as compared to the unoxidized tannins.Up to date, methods of combatting toxic organic pollutants have been largely based on microbial degradation or physical-chemical removal. A viable alternative approach to these methods that potentially is applicable for certain aromatic compounds, could be polymerizing these inhibitory compounds to non-toxic humus. The humus forming process is a natural mechanism in the forest environment that detoxifies tannic compounds before such compounds are released into the surface waters. The humus forming reactions were imitated in this study and were an effective method for eliminating the environmental impact of tannins in wastewater. Research should be continued to determine the extent to which humus forming processes can be applied for the treatment of other toxic organic contaminants

A complete transformational toolkit for compilers

In an earlier paper, one of the present authors presented a preliminary account of an equational logic called PIM. PIM is intended to function as a 'transformational toolkit' to be used by compilers and analysis tools for imperative languages, and has been applied to such problems as program slicing, symbolic evaluation, conditional constant propagation, and dependence analysis. PIM consists of the untyped lambda calculus extended with an algebraic rewriting system that characterizes the behavior of lazy stores and generalized conditionals. A major question left open in the earlier paper was whether there existed a complete equational axiomatization of PIM's semantics. In this paper, we answer this question in the affirmative for PIM's core algebraic component, PIMt, under the assumption of certain reasonable restrictions on term formation. We systematically derive the complete PIM logic as the culmination of a sequence of increasingly powerful equational systems starting from a straightforward 'interpreter' for closed PIM terms

Towards a complete transformational toolkit for compilers

PIM is an equational logic designed to function as a ``transformational toolkit'' for compilers and other programming tools that analyze and manipulate imperative languages.It has been applied to such problems as program slicing, symbolic evaluation, conditional constant propagation, and dependence analysis.PIM consists of the untyped lambda calculus extended with an algebraic data type that characterizes the behavior of lazy stores and generalized conditionals.A graph form of PIM terms is by design closely related to several intermediate representations commonly used in optimizing compilers. In this paper, we show that PIM's core algebraic component, PIM$_t$, possesses a complete equational axiomatization (under the assumption of certain reasonable restrictions on term formation). This has the practical consequence of guaranteeing that every semantics-preserving transformation on a program representable in PIM$_t$ can be derived by application of PIM$_t$ rules. We systematically derive the complete PIM$_t$ logic as the culmination of a sequence of increasingly powerful equational systems starting from a straightforward ``interpreter'' for closed PIM$_t$ terms. This work is an intermediate step in a larger program to develop a set of well-founded tools for manipulation of imperative programs by compilers and other systems that perform program analysis

Recovery from addiction: Behavioral economics and value-based decision making.

Behavioral economics provides a general framework to explain the shift in behavioral allocation from substance use to substance-free activities that characterizes recovery from addiction, but it does not attempt to explain the internal processes that prompt those behavioral changes. In this article we outline a novel analysis of addiction recovery based on computational work on value-based decision making (VBDM), which can explain how people with addiction are able to overcome the reinforcement pathologies and decision-making vulnerabilities that characterize the disorder. The central tenet of this account is that shifts in molar reinforcer preferences over time from substance use to substance-free activities can be attributed to changes in evidence accumulation rates and response thresholds in the context of choices involving substance use and substance-free alternatives. We discuss how this account can be reconciled with the established mechanisms of action of psychosocial interventions for addiction and demonstrate how it has the potential to empirically address longstanding debates regarding the nature of impairments to self-control in addiction. We also highlight conceptual and methodological issues that require careful consideration in translating VBDM to addiction and recovery

Shotgun and targeted MS analyses pinpoint the zampanolide-tubulin interacting site

Comunicaciones a congreso

Cosmological Magnetogenesis driven by Radiation Pressure

The origin of large scale cosmological magnetic fields remains a mystery, despite the continuous efforts devoted to that problem. We present a new model of magnetic field generation, based on local charge separation provided by an anisotropic and inhomogeneous radiation pressure. In the cosmological context, the processes we explore take place at the epoch of the reionisation of the Universe. Under simple assumptions, we obtain results (i) in terms of the order of magnitude of the field generated at large scales and (ii) in terms of its power spectrum. The amplitudes obtained (B ~ 8.10^(-6) micro-Gauss) are considerably higher than those obtained in usual magnetogenesis models and provide suitable seeds for amplification by adiabatic collapse and/or dynamo during structure formation.Comment: 9 pages, 2 figure

The Limits of Special Relativity

The Special Theory of Relativity and the Theory of the Electron have had an interesting history together. Originally the electron was studied in a non relativistic context and this opened up the interesting possibility that lead to the conclusion that the mass of the electron could be thought of entirely in electromagnetic terms without introducing inertial considerations. However the application of Special Relativity lead to several problems, both for an extended electron and the point electron. These inconsistencies have, contrary to popular belief not been resolved satisfactorily today, even within the context of Quantum Theory. Nevertheless these and subsequent studies bring out the interesting result that Special Relativity breaks down within the Compton scale or when the Compton scale is not neglected. This again runs contrary to an uncritical notion that Special Relativity is valid for point particles.Comment: 13 pages,Te

One loop MSbar gluon pole mass from the LCO formalism

We compute the one loop corrections to the pole mass of the gluon in the MSbar scheme in the Landau gauge in both the Curci-Ferrari model and the local composite operator formalism with Nf flavours of massless quarks. For the latter we determine an estimate for the gluon mass using the effective potential of a local dimension two composite operator and find, for example, m_{gluon} = 2.10 Lambda_MSbar in Yang-Mills theory.Comment: 7 latex page