University of Adelaide

About: University of Adelaide is a education organization based out in Adelaide, South Australia, Australia. It is known for research contribution in the topics: Population & Poison control. The organization has 27251 authors who have published 79167 publications receiving 2671128 citations. The organization is also known as: The University of Adelaide & Adelaide University.

Soil testing for heavy metals.

Abstract: Soil testing for metal contaminants is a continually evolving process aimed at improving the assessment of environmental and human health hazards associated with heavy metals in soils and plants. A number of challenges present themselves before accurate, reliable and precise contaminant hazard assessment criteria for soils and plants can be made. These include: sampling, extraction and analytical obstacles associated with the determination of trace levels of metals in environmental media; quality assurance and quality control issues associated with both extraction and analytical procedures (especially for metals where non‐compliance with regulatory standards may be penalised); and confounding environmental effects (e.g. rooting depth, soil salinity, Eh, pH, plant species, metal species) which limit the usefulness of the relationship between the current tests and actual hazards. These difficulties have combined to produce soil tests for heavy metals often poorly correlated with hazardwhether this ...

A typology of compound weather and climate events

Abstract: Compound weather and climate events describe combinations of multiple climate drivers and/or hazards that contribute to societal or environmental risk. Although many climate-related disasters are caused by compound events, the understanding, analysis, quantification and prediction of such events is still in its infancy. In this Review, we propose a typology of compound events and suggest analytical and modelling approaches to aid in their investigation. We organize the highly diverse compound event types according to four themes: preconditioned, where a weather-driven or climate-driven precondition aggravates the impacts of a hazard; multivariate, where multiple drivers and/or hazards lead to an impact; temporally compounding, where a succession of hazards leads to an impact; and spatially compounding, where hazards in multiple connected locations cause an aggregated impact. Through structuring compound events and their respective analysis tools, the typology offers an opportunity for deeper insight into their mechanisms and impacts, benefiting the development of effective adaptation strategies. However, the complex nature of compound events results in some cases inevitably fitting into more than one class, necessitating soft boundaries within the typology. Future work must homogenize the available analytical approaches into a robust toolset for compound-event analysis under present and future climate conditions. Research on compound events has increased vastly in the last several years, yet, a typology was absent. This Review proposes a comprehensive classification scheme, incorporating compound events that are preconditioned, multivariate, temporally compounding and spatially compounding events.

Origins and functional evolution of Y chromosomes across mammals

Abstract: Y chromosomes underlie sex determination in mammals, but their repeat-rich nature has hampered sequencing and associated evolutionary studies. Here we trace Y evolution across 15 representative mammals on the basis of high-throughput genome and transcriptome sequencing. We uncover three independent sex chromosome originations in mammals and birds (the outgroup). The original placental and marsupial (therian) Y, containing the sex-determining gene SRY, emerged in the therian ancestor approximately 180 million years ago, in parallel with the first of five monotreme Y chromosomes, carrying the probable sex-determining gene AMH. The avian W chromosome arose approximately 140 million years ago in the bird ancestor. The small Y/W gene repertoires, enriched in regulatory functions, were rapidly defined following stratification (recombination arrest) and erosion events and have remained considerably stable. Despite expression decreases in therians, Y/W genes show notable conservation of proto-sex chromosome expression patterns, although various Y genes evolved testis-specificities through differential regulatory decay. Thus, although some genes evolved novel functions through spatial/temporal expression shifts, most Y genes probably endured, at least initially, because of dosage constraints. Using high-throughput genome and transcriptome sequencing, Y chromosome evolution across 15 representative mammals is explored, with results providing evidence for three independent sex chromosome originations in mammals and birds. Mammalian Y chromosomes, known for their roles in sex determination and male fertility, often contain repetitive sequences that make them harder to assemble than the rest of the genome. To counter this problem Henrik Kaessmann and colleagues have developed a new transcript assembly approach based on male-specific RNA/genomic sequencing data to explore Y evolution across 15 species representing all major mammalian lineages. They find evidence for two independent sex chromosome originations in mammals and one in birds. Their analysis of the Y/W gene repertoires suggests that although some genes evolved novel functions in sex determination/spermatogenesis as a result of temporal/spatial expression changes, most Y genes probably persisted, at least initially, as a result of dosage constraints. In a parallel study, Daniel Bellott and colleagues reconstructed the evolution of the Y chromosome, using a comprehensive comparative analysis of the genomic sequence of X–Y gene pairs from seven placental mammals and one marsupial. They conclude that evolution streamlined the gene content of the human Y chromosome through selection to maintain the ancestral dosage of homologous X–Y gene pairs that regulate gene expression throughout the body. They propose that these genes make the Y chromosome essential for male viability and contribute to differences between the sexes in health and disease.

The Necessity and Sufficiency of Anytime Capacity for Stabilization of a Linear System Over a Noisy Communication Link—Part I: Scalar Systems

Abstract: In this paper, we review how Shannon's classical notion of capacity is not enough to characterize a noisy communication channel if the channel is intended to be used as part of a feedback loop to stabilize an unstable scalar linear system. While classical capacity is not enough, another sense of capacity (parametrized by reliability) called "anytime capacity" is necessary for the stabilization of an unstable process. The required rate is given by the log of the unstable system gain and the required reliability comes from the sense of stability desired. A consequence of this necessity result is a sequential generalization of the Schalkwijk-Kailath scheme for communication over the additive white Gaussian noise (AWGN) channel with feedback. In cases of sufficiently rich information patterns between the encoder and decoder, adequate anytime capacity is also shown to be sufficient for there to exist a stabilizing controller. These sufficiency results are then generalized to cases with noisy observations, delayed control actions, and without any explicit feedback between the observer and the controller. Both necessary and sufficient conditions are extended to continuous time systems as well. We close with comments discussing a hierarchy of difficulty for communication problems and how these results establish where stabilization problems sit in that hierarchy

Determination of the Electron Transfer Number for the Oxygen Reduction Reaction: From Theory to Experiment

Abstract: The forced convection methods on the rotating disk and ring-disk electrodes are carefully analyzed toward their use for calculation of the electron transfer number (n) for the oxygen reduction reaction (ORR) on various catalysts. It is shown that the widely used Koutechy–Levich (KL) method is not suitable to determine n for the ORR either theoretically or experimentally. From a theoretical viewpoint, the ORR is neither a single-step nor a one-way reaction and , therefore does not fulfill the assumptions of the KL method. From an experimental viewpoint, n is significantly dependent on the angular velocity of the rotating disk electrode, contradicting the assumption of constant n in the KL theory. An improved model is used to establish the aforementioned relationship between n and angular velocity. The recommended way to determine n for the ORR in alkaline electrolytes is to use the rotating ring-disk electrode with a properly biased Au ring, supplemented by the calibration of the collection efficiency.