Precious Metals-Exchange Rate Volatility Transmissions and Hedging Strategies

This study examines the conditional volatility and correlation dependency and interdependency for the four major precious metals (that is, gold, silver, platinum and palladium), while accounting for geopolitics within a multivariate system. The implications of the estimated results for portfolio designs and hedging strategies are also analyzed. The results for the four metals system show significant short-run and long-run dependencies and interdependencies to news and past volatility. These results have become more pervasive when the exchange rate and FFR are included. Monetary policy also has a differential impact on the precious metals and the exchange rate volatilities. Finally, the applications of the results show the optimal weights in a two-asset portfolio and the hedging ratios for long positions.exchange rates;hedging;volatility;shocks;precious metals;correlation;dependency;interdependency;multivariate

The P Cygni supergiant [OMN2000] LS1 – implications for the star formation history of W51

Original article can be found at: http://www.aanda.org/ Copyright The European Southern Observatory (ESO) DOI: 10.1051/0004-6361/200911980Aims. We investigate the nature of the massive star [OMN2000] LS1 and use these results to constrain the history of star formation within the host complex W51. Methods. We utilised a combination of near-IR spectroscopy and non-LTE model atmosphere analysis to derive the physical properties of [OMN2000] LS1 , and a combination of theoretical evolutionary calculations and Monte Carlo simulations to apply limits on the star formation history of W51. Results. We find the spectrum of [OMN2000] LS1 to be consistent with that of a P Cygni supergiant. With a temperature in the range of 13.2–13.7 kK and log( ) , it is significantly cooler, less luminous, and less massive than proposed by previous authors. The presence of such a star within W51 shows that star formation has been underway for at least 3 Myr, while the formation of massive O stars is still on going. The lack of a population of evolved red supergiants within the complex shows that the rate of formation of young massive clusters at ages 9 Myr was lower than currently observed. We find no evidence of internally triggered, sequential star formation within W51, and favour the suggestion that star formation has proceeded at multiple indepedent sites within the GMC. Along with other examples, such as the G305 and Carina star-forming regions, we suggest that W51 is a Galactic analogue of the ubiquitous star cluster complexes seen in external galaxies such as M51 and NGC2403.Peer reviewe

Accounting for the foreground contribution to the dust emission towards Kepler's supernova remnant

‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15061.xWhether or not supernovae contribute significantly to the overall dust budget is a controversial subject. Submillimetre (sub-mm) observations, sensitive to cold dust, have shown an excess at 450 and 850 μm in young remnants Cassiopeia A (Cas A) and Kepler. Some of the sub-mm emission from Cas A has been shown to be contaminated by unrelated material along the line of sight. In this paper, we explore the emission from material towards Kepler using sub-mm continuum imaging and spectroscopic observations of atomic and molecular gas, via H i, 12CO(J= 2–1) and 13CO(J= 2–1). We detect weak CO emission (peak T*A = 0.2–1 K, 1–2 km s−1 full width at half-maximum) from diffuse, optically thin gas at the locations of some of the sub-mm clumps. The contribution to the sub-mm emission from foreground molecular and atomic clouds is negligible. The revised dust mass for Kepler's remnant is 0.1–1.2 M⊙ , about half of the quoted values in the original study by Morgan et al., but still sufficient to explain the origin of dust at high redshifts.Peer reviewe

Enabling a High Throughput Real Time Data Pipeline for a Large Radio Telescope Array with GPUs

The Murchison Widefield Array (MWA) is a next-generation radio telescope currently under construction in the remote Western Australia Outback. Raw data will be generated continuously at 5GiB/s, grouped into 8s cadences. This high throughput motivates the development of on-site, real time processing and reduction in preference to archiving, transport and off-line processing. Each batch of 8s data must be completely reduced before the next batch arrives. Maintaining real time operation will require a sustained performance of around 2.5TFLOP/s (including convolutions, FFTs, interpolations and matrix multiplications). We describe a scalable heterogeneous computing pipeline implementation, exploiting both the high computing density and FLOP-per-Watt ratio of modern GPUs. The architecture is highly parallel within and across nodes, with all major processing elements performed by GPUs. Necessary scatter-gather operations along the pipeline are loosely synchronized between the nodes hosting the GPUs. The MWA will be a frontier scientific instrument and a pathfinder for planned peta- and exascale facilities.Comment: Version accepted by Comp. Phys. Com

The biochemical and biophysical characterisation of protein antibiotics targeting Pectobacterium spp. and Streptococcus agalactiae

Food security is the idea by which a population has enough food to sustain itself without famine. A large number of factors can influence the stability of food production, including diseases caused by microorganisms. Pectobacterium spp. is one of the leading causes of soft rot disease, resulting in crop losses both pre- and post-harvest. Bacteriocins are potent narrow spectrum protein antibiotics which target closely related bacteria to the producing strain. Ferredoxin-containing bacteriocins produced by and targeted towards Pectobacterium species have both a different domain organisation and uptake mechanism to all known Gram-negative bacteriocins. This work has shown that pectocins are able to pass through the outer membrane of Pectobacterium spp. by parasitising the ferredoxin uptake receptor, FusA. This uptake requires the pectocins to be flexible in order to pass through the lumen of the barrel and enter the periplasm. This work has shown an interaction between FusB and pectocin M1, suggesting a novel mechanism of uptake. Streptococcus agalactiae is the causative agent of disease in a wide range of hosts, ranging from human neonates to farmed Tilapia. S. agalactiae infection has a detrimental effect on the dairy industry each year as it is the leading cause of mastitis in cattle. As well as this, the prevalence of S. agalactiae in farmed fish has resulted in large numbers of infected fish and subsequently the infection of consumers. Bacteriocins produced by Gram-positive bacteria are often small modified peptides which target the peptidoglycan layer or cytoplasmic membrane of the target cell. However, a small number of protein bacteriocins produced by Gram-positive bacteria have been discovered, with the best characterised of these being lysostaphin. It has been shown that bacteriocins similar to lysostaphin are also produced by other Gram-positive bacteria, such as zoocin A produced by Streptococcus zooepidemicus. Prior to this work a novel protein bacteriocin produced by and targeted towards S. agalactiae, named agalacticin A, was discovered. It was predicted that this bacteriocin was similar in structure and function to zoocin A. This work has gone some way to structurally characterising agalacticin A, showing a two-domain structure joined by a flexible linker region allowing for the two domains to move independently. As well as this it has shown the importance of the histidine residues at the predicted active site confirming the similarities between agalacticin A and zoocin A. Together this work has gone some way to showing the potential of agalacticin A as a novel therapeutic. Altogether this work has characterised three novel bacteriocins active against pathogenic bacteria to gain a better understanding of their structure, mechanism of action and uptake

Dim Isolated Neutron Stars, Cooling and Energy Dissipation

The cooling and reheating histories of dim isolated neutron stars(DINs) are discussed. Energy dissipation due to dipole spindown with ordinary and magnetar fields, and due to torques from a fallback disk are considered as alternative sources of reheating which would set the temperature of the neutron star after the initial cooling era. Cooling or thermal ages are related to the numbers and formation rates of the DINs and therefore to their relations with other isolated neutron star populations. Interaction with a fallback disk, higher multipole fields and activity of the neutron star are briefly discussed.Comment: To appear in Astrophysics and Space Science, in the proceedings of the conference "Isolated Neutron Stars: from the Interior to the Surface", London, April 2006; eds. D. Page, R. Turolla and S. Zane. Revised version: with minor change and typos correcte

Multibeam Maser Survey of methanol and excited OH in the Magellanic clouds: new detections and maser abundance estimates

‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.12888.xPeer reviewe

Regular Expression Matching and Operational Semantics

Many programming languages and tools, ranging from grep to the Java String library, contain regular expression matchers. Rather than first translating a regular expression into a deterministic finite automaton, such implementations typically match the regular expression on the fly. Thus they can be seen as virtual machines interpreting the regular expression much as if it were a program with some non-deterministic constructs such as the Kleene star. We formalize this implementation technique for regular expression matching using operational semantics. Specifically, we derive a series of abstract machines, moving from the abstract definition of matching to increasingly realistic machines. First a continuation is added to the operational semantics to describe what remains to be matched after the current expression. Next, we represent the expression as a data structure using pointers, which enables redundant searches to be eliminated via testing for pointer equality. From there, we arrive both at Thompson's lockstep construction and a machine that performs some operations in parallel, suitable for implementation on a large number of cores, such as a GPU. We formalize the parallel machine using process algebra and report some preliminary experiments with an implementation on a graphics processor using CUDA.Comment: In Proceedings SOS 2011, arXiv:1108.279

Gut microbiome and brain functional connectivity in infants-a preliminary study focusing on the amygdala

Recently, there has been a surge of interest in the possibility that microbial communities inhabiting the human gut could affect cognitive development and increase risk for mental illness via the “microbiome-gut-brain axis.” Infancy likely represents a critical period for the establishment of these relationships, as it is the most dynamic stage of postnatal brain development and a key period in the maturation of the microbiome. Indeed, recent reports indicate that characteristics of the infant gut microbiome are associated with both temperament and cognitive performance. The neural circuits underlying these relationships have not yet been delineated. To address this gap, resting-state fMRI scans were acquired from 39 1-year-old human infants who had provided fecal samples for identification and relative quantification of bacterial taxa. Measures of alpha diversity were generated and tested for associations with measures of functional connectivity. Primary analyses focused on the amygdala as manipulation of the gut microbiota in animal models alters the structure and neurochemistry of this brain region. Secondary analyses explored functional connectivity of nine canonical resting-state functional networks. Alpha diversity was significantly associated with functional connectivity between the amygdala and thalamus and between the anterior cingulate cortex and anterior insula. These regions play an important role in processing/responding to threat. Alpha diversity was also associated with functional connectivity between the supplementary motor area (SMA, representing the sensorimotor network) and the inferior parietal lobule (IPL). Importantly, SMA-IPL connectivity also related to cognitive outcomes at 2 years of age, suggesting a potential pathway linking gut microbiome diversity and cognitive outcomes during infancy. These results provide exciting new insights into the gut-brain axis during early human development and should stimulate further studies into whether microbiome-associated changes in brain circuitry influence later risk for psychopathology