316 research outputs found

    What do we know about individual equity options?

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    This paper examines the empirical literature on individual equity options, discussing results in areas of consensus, showing findings in areas of disagreement and providing a guide for future research (especially highlighting analyses that cannot be performed with index options). Key topics include the impact of equity option listings on the underlying stock market, option market efficiency, anomalies in equity option returns, option market microstructure, investors' behavioural biases, option price discovery and private information revealed in equity option markets. Some directions for future research include the determinants of equity option returns and the effect of algorithmic trading in option markets

    Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project

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    In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The late Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of five sensitivity experiments. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, considering the models are set up with their own parameter settings. For the Pliocene, the results demonstrate the difficulty of all six models used here to simulate a significant retreat or re-advance of the East Antarctic ice grounding line, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. The specific sea-level contribution of the Antarctic ice sheet at this point cannot be conclusively determined, whereas improved grounding line physics could be essential for a correct representation of the migration of the grounding-line of the Antarctic ice sheet during the Pliocene

    Enhanced Fe-centered redox flexibility in Fe–Ti heterobimetallic complexes

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    Previously, we reported the synthesis of Ti[N(o-(NCH2P(iPr)2)C6H4)3] and the Fe–Ti complex, FeTi[N(o-(NCH2P(iPr)2)C6H4)3], abbreviated as TiL (1), and FeTiL (2), respectively. Herein, we describe the synthesis and characterization of the complete redox families of the monometallic Ti and Fe–Ti compounds. Cyclic voltammetry studies on FeTiL reveal both reduction and oxidation processes at −2.16 and −1.36 V (versus Fc/Fc+), respectively. Two isostructural redox members, [FeTiL]+ and [FeTiL]− (2ox and 2red, respectively) were synthesized and characterized, along with BrFeTiL (2-Br) and the monometallic [TiL]+ complex (1ox). The solid-state structures of the [FeTiL]+/0/– series feature short metal–metal bonds, ranging from 1.94–2.38 Å, which are all shorter than the sum of the Ti and Fe single-bond metallic radii (cf. 2.49 Å). To elucidate the bonding and electronic structures, the complexes were characterized with a host of spectroscopic methods, including NMR, EPR, and 57Fe Mössbauer, as well as Ti and Fe K-edge X-ray absorption spectroscopy (XAS). These studies, along with hybrid density functional theory (DFT) and time-dependent DFT calculations, suggest that the redox processes in the isostructural [FeTiL]+,0,– series are primarily Fe-based and that the polarized Fe–Ti π-bonds play a role in delocalizing some of the additional electron density from Fe to Ti (net 13%)

    PLISMIP-ANT, an ice-sheet model intercomparison project

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    In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The late Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of five sensitivity experiments. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, considering the models are set up with their own parameter settings. For the Pliocene, the results demonstrate the difficulty of all six models used here to simulate a significant retreat or re-advance of the East Antarctic ice grounding line, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. The specific sea-level contribution of the Antarctic ice sheet at this point cannot be conclusively determined, whereas improved grounding line physics could be essential for a correct representation of the migration of the grounding-line of the Antarctic ice sheet during the Pliocene

    One health surveillance for rabies : a case study of integrated bite case management in Albay Province, Philippines

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    Canine rabies is a significant public health concern and economic burden in the Philippines. Animal Bite Treatment Centers (ABTCs) that provide post-exposure prophylaxis (PEP) to bite patients have been established across the country, but the incidence of bite patient presentations has grown unsustainably, whilst rabies transmission in domestic dogs has not been controlled. Moreover, weak surveillance leads to low case detection and late outbreak responses. Here we investigated the potential for Integrated Bite Case Management (IBCM) to improve rabies detection in Albay province. Using information obtained from animal bite histories combined with phone follow-ups and field investigations, we demonstrated that IBCM resulted in a fourfold increase in case detection over 13 months of study compared to the prior period. Bite patient incidence across Albay was very high (>600/100,000 persons/year) with PEP administered mostly indiscriminately. Clinic attendance reflected availability of PEP and proximity to ABTCs rather than rabies incidence (<3% of patient presentations were from “probable” or confirmed rabies exposures) and is therefore not a suitable indicator of rabies burden. Further analysis of the IBCM data suggests that rabies transmission is mostly localized with focal cases from the previous month and current cases in neighbouring villages being most predictive of future rabies occurrence. We conclude that investigations of suspicious biting incidents identified through IBCM have potential to foster intersectoral relationships, and collaborative investments between public health and veterinary services, enabling the One Health ethos to be applied in a more sustainable and equitable way. Triage of patients and investigations of suspect dogs offer an effective tool for improved PEP provisioning and reduction of unnecessary expenditure, whilst targeted field investigations should lead to increased and earlier detection of rabid dogs. Given the enduring risk of re-introductions from neighbouring populations, enhanced surveillance is critical to achieving and maintaining rabies freedom

    Understanding Climate Change: A primer for local government officials in the Philippines

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    Understanding the impacts of climate change on agriculture, associated landscapes and natural resources in general is crucial if local development efforts are to be tailored towards addressing the impacts of climate change. Simplification of scientific concepts can help local planners to introduce and then mainstream strategies that have factored in the impacts from climate change

    Correlation of cell growth and heterologous protein production by Saccharomyces cerevisiae

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    With the increasing demand for biopharmaceutical proteins and industrial enzymes, it is necessary to optimize the production by microbial fermentation or cell cultures. Yeasts are well established for the production of a wide range of recombinant proteins, but there are also some limitations; e.g., metabolic and cellular stresses have a strong impact on recombinant protein production. In this work, we investigated the effect of the specific growth rate on the production of two different recombinant proteins. Our results show that human insulin precursor is produced in a growth-associated manner, whereas alpha-amylase tends to have a higher yield on substrate at low specific growth rates. Based on transcriptional analysis, we found that the difference in the production of the two proteins as function of the specific growth rate is mainly due to differences in endoplasmic reticulum processing, protein turnover, cell cycle, and global stress response. We also found that there is a shift at a specific growth rate of 0.1 h(-1) that influences protein production. Thus, for lower specific growth rates, the alpha-amylase and insulin precursor-producing strains present similar cell responses and phenotypes, whereas for higher specific growth rates, the two strains respond differently to changes in the specific growth rate
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