Forecasting Spikes in Electricity Prices

In many electricity markets, retailers purchase electricity at an unregulated spot price and sell to consumers at a heavily regulated price. Consequently the occurrence of extreme movements in the spot price represents a major source of risk to retailers and the accurate forecasting of these extreme events or price spikes is an important aspect of effective risk management. Traditional approaches to modeling electricity prices are aimed primarily at predicting the trajectory of spot prices. By contrast, this paper focuses exclusively on the prediction of spikes in electricity prices. The time series of price spikes is treated as a realization of a discrete-time point process and a nonlinear variant of the autoregressive conditional hazard (ACH) model is used to model this process. The model is estimated using half-hourly data from the Australian electricity market for the sample period 1 March 2001 to 30 June 2007. The estimated model is then used to provide one-step-ahead forecasts of the probability of an extreme event for every half hour for the forecast period, 1 July 2007 to 30 September 2007, chosen to correspond to the duration of a typical forward contract. The forecasting performance of the model is then evaluated against a benchmark that is consistent with the assumptions of commonly-used electricity pricing models.Electricity Prices, Price Spikes, Autoregressive Conditional Duration, Autoregressive

Sleep preserves original and distorted memory traces

Retrieval facilitates the long-term retention of memories, but may also enable stored representations to be updated with new information that is available at the time of retrieval. However, if information integrated during retrieval is erroneous, future recall can be impaired: a phenomenon known as retrieval-induced distortion (RID). Whether RID causes an “overwriting” of existing memory traces or leads to the co-existence of original and distorted memory traces is unknown. Because sleep enhances memory consolidation, the effects of sleep after RID can provide novel insights into the structure of updated memories. As such, we investigated the effects of sleep on memory consolidation following RID. Participants encoded word locations and were then tested before (T1) and after (T2) an interval of sleep or wakefulness. At T2, the majority of words were placed closer to the locations retrieved at T1 than to the studied locations, consistent with RID. After sleep compared with after wake, the T2-retrieved locations were closer to both the studied locations and the T1-retrieved locations. These findings suggest that RID leads to the formation of an additional memory trace that corresponds to a distorted variant of the same encoding event, which is strengthened alongside the original trace during sleep. More broadly, these data provide evidence for the importance of sleep in the preservation and adaptive updating of memories

The benefits of targeted memory reactivation for consolidation in sleep are contingent on memory accuracy and direct cue-memory associations

Objectives: To investigate how the effects of targeted memory reactivation (TMR) are influenced by memory accuracy prior to sleep and the presence or absence of direct cue-memory associations. Methods: 30 participants associated each of 50 pictures with an unrelated word and then with a screen location in two separate tasks. During picture-location training, each picture was also presented with a semantically related sound. The sounds were therefore directly associated with the picture locations but indirectly associated with the words. During a subsequent nap, half of the sounds were replayed in slow wave sleep (SWS) (TMR). The effect of TMR on memory for the picture locations (direct cue-memory associations) and picture-word pairs (indirect cue-memory associations) was then examined. Results: TMR reduced overall memory decay for recall of picture locations. Further analyses revealed a benefit of TMR for picture locations recalled with a low degree of accuracy prior to sleep, but not those recalled with a high degree of accuracy. The benefit of TMR for low accuracy memories was predicted by time spent in SWS. There was no benefit of TMR for memory of the picture-word pairs, irrespective of memory accuracy prior to sleep. Conclusions: TMR provides the greatest benefit to memories recalled with a low degree of accuracy prior to sleep. The memory benefits of TMR may also be contingent on direct cue-memory associations

Stocking rate guidelines for rural small holdings, Swan Coastal Plain and Darling Scarp and surrounds, Western Australia

Small rural holdings are often owned by people who want to pursue a semi-rural lifestyle but who are inexperienced in land management issues. This can result in landholders stocking their properties with animals at rates higher than the land resources can sustain, leading to degradation problems such as soil erosion, water pollution and damage to vegetation. This document provides information and guidelines to help planners, developers, local authorities and land owners determine the base stocking rates for rural small holdings on the Swan Coastal Plain and Darling Scarp and immediate surrounds. The advice utilises Agriculture Western Australia’s rural stocking rate guidelines for rainfed pastures in the high rainfall areas (\u3e 650 mm) in the south-west of Western Australia

Lipid phosphate phosphatases dimerise, but this interaction is not required for in vivo activity

BACKGROUND: Lipid phosphate phosphatases (LPPs) are integral membrane proteins believed to dephosphorylate bioactive lipid messengers, so modifying or attenuating their activities. Wunen, a Drosophila LPP homologue, has been shown to play a pivotal role in primordial germ cell (PGC) migration and survival during embryogenesis. It has been hypothesised that LPPs may form oligomeric complexes, and may even function as hexamers. We were interested in exploring this possibility, to confirm whether LPPs can oligomerise, and if they do, whether oligomerisation is required for either in vitro or in vivo activity. RESULTS: We present evidence that Wunen dimerises, that these associations require the last thirty-five C-terminal amino-acids and depend upon the presence of an intact catalytic site. Expression of a truncated, monomeric form of Wunen in Drosophila embryos results in perturbation of germ cell migration and germ cell loss, as observed for full-length Wunen. We also observed that murine LPP-1 and human LPP-3 can also form associations, but do not form interactions with Wunen or each other. Furthermore, Wunen does not form dimers with its closely related counterpart Wunen-2. Finally we discovered that addition of a trimeric myc tag to the C-terminus of Wunen does not prevent dimerisation or in vitro activity, but does prevent activity in vivo. CONCLUSION: LPPs do form complexes, but these do not seem to be specifically required for activity either in vitro or in vivo. Since neither dimerisation nor the C-terminus seem to be involved in substrate recognition, they may instead confer structural or functional stability through dimerisation. The results indicate that the associations we see are highly specific and occur only between monomers of the same protein

Identification of Genes Whose Expression Overlaps Age Boundaries and Correlates with Risk Groups in Paediatric and Adult Acute Myeloid Leukaemia

Few studies have compared gene expression in paediatric and adult acute myeloid leukaemia (AML). In this study, we have analysed mRNA-sequencing data from two publicly accessible databases: (1) National Cancer Institute's Therapeutically Applicable Research to Generate Effective Treatments (NCI-TARGET), examining paediatric patients, and (2) The Cancer Genome Atlas (TCGA), examining adult patients with AML. With a particular focus on 144 known tumour antigens, we identified STEAP1, SAGE1, MORC4, SLC34A2 and CEACAM3 as significantly different in their expression between standard and low risk paediatric AML patient subgroups, as well as between poor and good, and intermediate and good risk adult AML patient subgroups. We found significant differences in event-free survival (EFS) in paediatric AML patients, when comparing standard and low risk subgroups, and quartile expression levels of BIRC5, MAGEF1, MELTF, STEAP1 and VGLL4. We found significant differences in EFS in adult AML patients when comparing intermediate and good, and poor and good risk adult AML patient subgroups and quartile expression levels of MORC4 and SAGE1, respectively. When examining Kyoto Encyclopedia of Genes and Genomes (KEGG) (2016) pathway data, we found that genes altered in AML were involved in key processes such as the evasion of apoptosis (BIRC5, WNT1) or the control of cell proliferation (SSX2IP, AML1-ETO). For the first time we have compared gene expression in paediatric AML patients with that of adult AML patients. This study provides unique insights into the differences and similarities in the gene expression that underlies AML, the genes that are significantly differently expressed between risk subgroups, and provides new insights into the molecular pathways involved in AML pathogenesis

Analogous Cellular Contribution and Healing Mechanisms Following Digit Amputation and Phalangeal Fracture in Mice

Regeneration of amputated structures is severely limited in humans and mice, with complete regeneration restricted to the distal portion of the terminal phalanx (P3). Here, we investigate the dynamic tissue repair response of the second phalangeal element (P2) post amputation in the adult mouse, and show that the repair response of the amputated bone is similar to the proximal P2 bone fragment in fracture healing. The regeneration-incompetent P2 amputation response is characterized by periosteal endochondral ossification resulting in the deposition of new trabecular bone, corresponding to a significant increase in bone volume; however, this response is not associated with bone lengthening. We show that cells of the periosteum respond to amputation and fracture by contributing both chondrocytes and osteoblasts to the endochondral ossification response. Based on our studies, we suggest that the amputation response represents an attempt at regeneration that ultimately fails due to the lack of a distal organizing influence that is present in fracture healing

Prospectus, September 3, 2008

https://spark.parkland.edu/prospectus_2008/1016/thumbnail.jp

Prospectus, September 17, 2008

https://spark.parkland.edu/prospectus_2008/1018/thumbnail.jp

Tax Policy Forum: Review of Tax Expenditures, Budget 2016

In the 2016 budget the Department of Finance announced that it intended to review a number of tax expenditures with the objective of identifying and eliminating poorly targeted or inefficient tax measures. In this article, the authors discuss the concept and theory of tax expenditures and then debate the merits of some of the more significant tax expenditures with the objective of identifying those that might be considered poorly targeted or inefficient