An Evaluation of the S2Ia switched-current architecture for (delta)(sigma) modulator ADCs

Switched-Current (SI) is a design methodology by which discrete time, current mode, analog circuits can be implemented using standard digital CMOS processes, allowing the addition of analog signal processing circuits, analog to digital converters (ADCs), digital to analog converters (DACs) and other analog and mixed-signal circuits to otherwise digital only microchips without the need and expense of any extra fabrication steps. SI circuits operate by employing a secondary effect in CMOS circuits, a transistor\u27s gate capacitance, to store charge and thus form a current memory cell. A current memory cell is one of the basic building blocks found in most SI circuits and is usually the distinguishing feature of the various approaches to SI circuit design. Delta Sigma Modulators (DSMs) are discrete time, mixed-signal circuits making them well suited to implementation using the SI methodology. These circuits can form the basis of either an ADC or DAC and thus provide a good example of the SI technique employing a particular current memory cell implementation. For this work, a First Order DSM-based ADC was designed and simulated to verify the feasibility of a variant of the S2I Switched-Current Memory Cell architecture, the S2Ia Switched-Current Memory Cell, in a low-voltage, digital, 0.5/j.m CMOS process. The A D C design was targeted towards voiceband (4kHz bandwidth) applications over which it achieved a 6-bit resolution and separately attained a greater than 80kHz bandwidth. Extension of the First Order DSM employed in this design to a Second Order DSM would increase the resolution to at least 8-bits without sacrificing bandwidth. Although potentially less accurate than the S2I Switched-Current Memory Cell, a S2Ia cell has the advantage of requiring only two clock signals to the S2I cell\u27s four. Further, for cascades of S2Ia cells the number of clock signals remains two while a S2I cell cascade requires six separate clock signals. S2Ia-based circuits therefore require less complex clock generation circuitry and fewer clock lines

Is geographic diversification sufficient to limit contract grower risk?

Lending and financial institutions have looked for a variety of ways to expand their portfolios into agriculture, but because of the risks associated with lending to farmers who lack traditional forms of collateral, they face price and yield risks, causing these inroads to be limited. Market-based instruments are readily available for price risk. Organised exchanges offering the most basic of these instruments, futures and options, have operated for a long time, providing transparency to the market and low-cost risk transfer tools for those able to access them. While the use of price risk management instruments is an incomplete solution, it has sufficient merits on its own and will make the overall burden of risk more bearable. The use of these instruments and multi-peril crop insurance products is expensive and does not provide full protection for financial lending institutions to limit their credit risk exposure. This article determines whether geographic diversification would be sufficient as a risk management tool for lending institutions to limit their credit risk.Geographic diversification, Contract grower, Risk, Lending, Rainfall, Yield, Agricultural Finance,

A clear and present danger: impacts of poisoning on a vulture population and the effect of poison response activities

Vultures in Africa are being poisoned deliberately by poachers to prevent the birds alerting authorities to the poachers’ illegal activities, or for harvesting and sale of body parts for use in witchcraft. Hundreds of vultures can be killed at a single poisoned elephant Loxodonta africana carcass, and although field staff trained in poison response activities can limit the damage, mortalities remain numerous. We used the population viability analysis programme VORTEX to simulate seven 100-year-long scenarios investigating various rates of poisoning mortalities and the remedial effects of poison response activities on a population of Critically Endangered white-backed vultures Gyps africanus breeding in Kruger National Park, South Africa. In six scenarios the population declined; in three scenarios the population remained extant over the 100-year simulations but declined by 60-90% from a starting size of 2,400 individuals.In two scenarios one poisoned elephant carcass left untreated and causing the greatest number of vulture deaths was modelled as a catastrophic event with a 50% probability of annual occurrence, which resulted in a 100% probability of population extinction, with a mean time to extinction of 55-62 years. Effective poison response activities were modelled as a 70% reduction of mortality at each poisoned elephant carcass and resulted in population persistence after 100 years but with a c. 90% reduction in size (final n = 205). We highlight that although poison response activities will not prevent poisoning from occurring, they form an essential part of wider conservation actions designed to prevent local extinctions of vultures or other vulnerable species

An integrated approach to risk management for a bulk coal export logistic chain

In an ever-changing world where economic growth is inter-alia dependent on the export of bulk minerals, the risk and the severity of risk incidences in the bulk mineral supply chain should be minimised. In South Africa the export of coal is a large contributor to the GDP and any risk to this supply chain will directly affect its contribution to the GDP. Although all the stakeholders in the bulk coal export logistic chain manage the risk in their own domain, the bulk export logistic chain represents a supply chain structure where the risk of one stakeholder influences the risk of another stakeholder. Therefore, to reduce the total risk, an integrated risk management framework for the bulk coal export logistic chain is required. This study investigated the risks and the risk management processes in the bulk coal export supply chain. This logistic chain was chosen based on the monetary value the chain represents and the contribution to the GDP. A qualitative research design was used with one-on-one interviews and content analysis of risk management policies and procedures to obtain the data. The study revealed that there are risks that could not be managed on an individual stakeholder level and therefore an integrated risk management approach that considers the total bulk coal logistics export chain is required.Entrepreneurship and Supply Chain, Transport, Tourism and Logistics ManagementM. Com (Logistics Management

Revisiting the effect of capture heterogeneity on survival estimates in capture-mark-recapture studies: does it matter?

Recently developed capture-mark-recapture methods allow us to account for capture heterogeneity among individuals in the form of discrete mixtures and continuous individual random effects. In this article, we used simulations and two case studies to evaluate the effectiveness of continuously distributed individual random effects at removing potential bias due to capture heterogeneity, and to evaluate in what situation the added complexity of these models is justified. Simulations and case studies showed that ignoring individual capture heterogeneity generally led to a small negative bias in survival estimates and that individual random effects effectively removed this bias. As expected, accounting for capture heterogeneity also led to slightly less precise survival estimates. Our case studies also showed that accounting for capture heterogeneity increased in importance towards the end of study. Though ignoring capture heterogeneity led to a small bias in survival estimates, such bias may greatly impact management decisions. We advocate reducing potential heterogeneity at the sampling design stage. Where this is insufficient, we recommend modelling individual capture heterogeneity in situations such as when a large proportion of the individuals has a low detection probability (e.g. in the presence of floaters) and situations where the most recent survival estimates are of great interest (e.g. in applied conservation)

First confirmed records of Rüppell’s Vultures (Gyps rueppelli) in Malawi.

No abstract

Pastoral therapy and extra-marital affairs : a narrative approach

Extra-marital affairs are the main reason for divorce in western society. Pastoral therapists usually operate within a modernistic theology and use their 'expert' knowledge of theological ethics to confront the unfaithful spouse - a pastoral therapeutic approach that neither delivers the desired results, nor honours the client's expertise and freedom. This study endeavoured to socially construct pastoral therapy using the principles of postmodernistic social construction discourse with couples/spouses where one spouse is or was engaged in an extramarital affair. The relation between a modernistic epistemology and a postmodernistic epistemology, and how this relation affects theology, practical theology and pastoral therapy were explored. The propium of pastoral therapy in a postmodemistic paradigm and the implications of a narrative approach in pastoral therapy for theological ethics were reflected upon. A narrative description of extra-marital affairs was constructed and some of the cultural discourses which co-constitute extra-marital affairs were discussed. The pastoral therapist and clients were simultaneously in conversation with ethical discourses and relational, personal and emotional discourses, thus co-constructing new alternatives and possibilities. During these multiple reflexive conversations, some of the cultural discourses (eros; self-fulfilment; extra-marital sex and hedonism) which co-constitute extra-marital affairs were deconstructed. In the light of the usual limitations of the life-span of an extra-marital affair, the pastoral therapist and faithful spouses socially constructed alternatives and possibilities for their lives to enable them to outstay the extra-marital affair of the unfaithful spouse. Multiple reflexive conversations with (un)faithful spouses co-constructed, with relational and ethical discourses, a narrative approach in pastoral therapy. The use of externalisation and ritualisation in a narrative approach in pastoral therapy concerning extra-marital affairs was explored. A sense of guilt and secrets were also themes in multiple reflexive conversations with unfaithful spouses. This prompted reflection on the use of Scripture in a narrative approach in pastoral therapy. The relation between the biological-psychological aspects of extra-marital affairs and narrative therapy are also briefly explored.Philosophy, Practical and Systematic TheologyD. Th. (Practical Theology

The Net Worth method as technique to quantify income during investigation of financial crime

It is a well-known fact that criminals derive an income from their illegal activities, live lavish lifestyles, flaunt their wealth for all to see and acquire luxury goods. It is also a well known fact that criminals living from the proceeds of crime do not want to not want to keep financial records of their transactions or illegitimate business for fear of being detected by the authorities and to escape being taxed. It is also a known fact that criminals do not declare income from criminal activities for income tax purposes to the revenue authorities for fear of the illegal origin of the income being made known to the investigating authorities and law enforcement. During the investigation of financial crimes, such as tax evasion and money laundering, it may be required that the amount or value of money, income or assets accrued by a subject is determined in order to determine for instance their liability to pay tax. This research project examines the Net Worth method as an indirect method to circumstantially quantify income during the investigation of financial crime.Police PracticeM.Tech. (Forensic Investigation

Survival and population dynamics of the Marabou Stork in an isolated population, Swaziland

Investigating the ecology of long lived birds is particularly challenging owing to the time scales involved. Here an analysis is presented of a long term study of the survival and population dynamics of the marabou stork (Leptoptilos crumeniferus), a wide ranging scavenging bird from Sub-Saharan Africa. Using resightings data of tagged nestlings and free flying birds we show that the stork population can be divided into three general life stages with unique survival probabilities and fecundities. Fecundity of the storks is inversely related to rainfall during their breeding season. Corroborative evidence for a metapopulation structure is discussed highlighting the impact of the Swaziland birds on the ecology of the species in the broader region. The importance of tag loss or illegibility over time is highlighted. Clearly, any attempt at conserving a species will require a detailed understanding of its population structure, of the sort examined here