16,142 research outputs found
The More Cooperation, the More Competition? A Cournot Analysis of the Benefits of Electric Market Coupling
Market coupling in Belgian and Dutch markets would permit more efficient use of intercountry transmission, 1) by counting only net flows against transmission limits, 2) by improving access to the Belgian market, and 3) by eliminating the mismatch in timing between interface auctions and the energy spot market. A Cournot market model that accounts for the region’s transmission pricing rules and limitations is used to simulate market outcomes with and without market coupling. This accounts for 1) and 2). Market coupling improves social surplus in the order of 108 €/year, unless it encourages the largest producer in the region to switch from a price-taking strategy in Belgium to a Cournot strategy due to a perceived diminishment of the threat of regulatory intervention. Benefit to Dutch consumers depends on the behavior of this company. The results illustrate how large-scale oligopoly models can be useful for assessing market integration
Black hole feedback in a multiphase interstellar medium
Ultrafast outflows (UFOs) from supermassive black holes (SMBHs) are thought
to regulate the growth of SMBHs and host galaxies, resulting in a number of
observational correlations. We present high-resolution numerical simulations of
the impact of a thermalized UFO on the ambient gas in the inner part of the
host galaxy. Our results depend strongly on whether the gas is homogeneous or
clumpy. In the former case all of the ambient gas is driven outward rapidly as
expected based on commonly used energy budget arguments, while in the latter
the flows of mass and energy decouple. Carrying most of the energy, the shocked
UFO escapes from the bulge via paths of least resistance, taking with it only
the low-density phase of the host. Most of the mass is however in the
high-density phase, and is affected by the UFO much less strongly, and may even
continue to flow inwards. We suggest that the UFO energy leakage through the
pores in the multiphase interstellar medium (ISM) may explain why observed
SMBHs are so massive despite their overwhelmingly large energy production
rates. The multiphase ISM effects reported here are probably under-resolved in
cosmological simulations but may be included in prescriptions for active
galactic nuclei feedback in future simulations and in semi-analytical models.Comment: 12 pages, 8 figures, accepted in MNRA
Discovery of 28 pulsars using new techniques for sorting pulsar candidates
Modern pulsar surveys produce many millions of candidate pulsars, far more
than can be individually inspected. Traditional methods for filtering these
candidates, based upon the signal-to-noise ratio of the detection, cannot
easily distinguish between interference signals and pulsars. We have developed
a new method of scoring candidates using a series of heuristics which test for
pulsar-like properties of the signal. This significantly increases the
sensitivity to weak pulsars and pulsars with periods close to interference
signals. By applying this and other techniques for ranking candidates from a
previous processing of the Parkes Multi-beam Pulsar Survey, 28 previously
unknown pulsars have been discovered. These include an eccentric binary system
and a young pulsar which is spatially coincident with a known supernova
remnant.Comment: To be published in Monthly Notices of the Royal Astronomical Society.
11 pages, 9 figure
Development and validation of 'AutoRIF': Software for the automated analysis of radiation-induced foci
Copyright @ 2012 McVean et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: The quantification of radiation-induced foci (RIF) to investigate the induction and subsequent repair of DNA double strands breaks is now commonplace. Over the last decade systems specific for the automatic quantification of RIF have been developed for this purpose, however to ask more mechanistic questions on the spatio-temporal aspects of RIF, an automated RIF analysis platform that also quantifies RIF size/volume and relative three-dimensional (3D) distribution of RIF within individual nuclei, is required.
Results: A java-based image analysis system has been developed (AutoRIF) that quantifies the number, size/volume and relative nuclear locations of RIF within 3D nuclear volumes. Our approach identifies nuclei using the dynamic Otsu threshold and RIF by enhanced Laplacian filtering and maximum entropy thresholding steps and, has an application ‘batch optimisation’ process to ensure reproducible quantification of RIF. AutoRIF was validated by comparing output against manual quantification of the same 2D and 3D image stacks with results showing excellent concordance over a whole range of sample time points (and therefore range of total RIF/nucleus) after low-LET radiation exposure.
Conclusions: This high-throughput automated RIF analysis system generates data with greater depth of information and reproducibility than that which can be achieved manually and may contribute toward the standardisation of RIF analysis. In particular, AutoRIF is a powerful tool for studying spatio-temporal relationships of RIF using a range of DNA damage response markers and can be run independently of other software, enabling most personal computers to perform image analysis. Future considerations for AutoRIF will likely include more complex algorithms that enable multiplex analysis for increasing combinations of cellular markers.This article is made available through the Brunel Open Access Publishing Fund
An analysis of the timing irregularities for 366 pulsars
We provide an analysis of timing irregularities observed for 366 pulsars.
Observations were obtained using the 76-m Lovell radio telescope at the Jodrell
Bank Observatory over the past 36 years. These data sets have allowed us to
carry out the first large-scale analysis of pulsar timing noise over time
scales of > 10yr, with multiple observing frequencies and for a large sample of
pulsars. Our sample includes both normal and recycled pulsars. The timing
residuals for the pulsars with the smallest characteristic ages are shown to be
dominated by the recovery from glitch events, whereas the timing irregularities
seen for older pulsars are quasi-periodic. We emphasise that previous models
that explained timing residuals as a low-frequency noise process are not
consistent with observation.Comment: Accepted by MNRAS. High resolution images available from the article
on AD
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