1,304 research outputs found
Review of the Effectiveness of Impulse Testing for the Evaluation of Cable Insulation Quality and Recommendations for Quality Testing
Abstract— This project investigates impulse breakdown testing as a means of determining the as constructed standard of MV power cable. A literature survey is undertaken to elucidate the place of this test in an overall cable test regime and to determine the factors that impact on the performance of the test method. Testing was undertaken on ESB Networks cables to establish if a merit order ranking was feasible based on this test and to determine if the test could detect defects in the inner semiconducting layer. Based on this, conclusions and recommendations are made regarding the overall applicability and usefulness of this test
A search for radio emission from exoplanets around evolved stars
The majority of searches for radio emission from exoplanets have to date
focused on short period planets, i.e., the so-called hot Jupiter type planets.
However, these planets are likely to be tidally locked to their host stars and
may not generate sufficiently strong magnetic fields to emit electron cyclotron
maser emission at the low frequencies used in observations (typically >150
MHz). In comparison, the large mass-loss rates of evolved stars could enable
exoplanets at larger orbital distances to emit detectable radio emission. Here,
we first show that the large ionized mass-loss rates of certain evolved stars
relative to the solar value could make them detectable with the Low Frequency
Array (LOFAR) at 150 MHz ( = 2 m), provided they have surface magnetic
field strengths >50 G. We then report radio observations of three long period
(>1 au) planets that orbit the evolved stars Gem, Dra, and
UMi using LOFAR at 150 MHz. We do not detect radio emission from any
system but place tight 3 upper limits of 0.98, 0.87, and 0.57 mJy on
the flux density at 150 MHz for Gem, Dra, and UMi,
respectively. Despite our non-detections these stringent upper limits highlight
the potential of LOFAR as a tool to search for exoplanetary radio emission at
meter wavelengths.Comment: 9 pages, 3 figure
Virtual Proximity to Promote Expatriate Cultural Adjustment, Innovation, and the Reduction of Stress Levels
Given the dramatic increase in the number of expatriates living and working abroad, there is a need to advance the research into how to make sure these employees achieve success on their assignments. Often, these expatriates assume managerial roles and are intended to be the gatekeepers of information. Typically, this information is necessary for the success of their colleagues, in both their home country and their host country. The expatriate’s role is to facilitate the integration of organizational knowledge from both their home and host countries, as well as key sources in their host country’s local environment. However, historically, there has been an exceptionally high failure rate in expatriate engagements. There are various factors discussed in the literature related to this failure rate including the stress of cultural integration and isolation from family. This often interferes with the expatriate being able to perform of their key responsibilities, which is to innovate. This research will launch pilot studies to investigate the use of social media, and computer mediated communications, to develop virtual proximity, its effects on cultural integration, the maintenance of professional relationships on a global scale, and its effect on the reduction of stress and the innovation process
The Cosmology of String Theoretic Axions
String theory posesses numerous axion candidates. The recent realization that
the compactification radius in string theory might be large means that these
states can solve the strong CP problem. This still leaves the question of the
cosmological bound on the axion mass. Here we explore two schemes for
accommodating such light axions in cosmology. In the first, we note that in
string theory the universe is likely to be dominated early on by the coherent
oscillations of some moduli. The usual moduli problem assumes that these fields
have masses comparable to the gravitino. We argue that string moduli are likely
to be substantially more massive, eliminating this problem. In such cosmologies
the axion bound is significantly weakened. Plausible mechanisms for generating
the baryon number density are described. In the second, we point out that in
string theory, the axion potentials might be much larger at early times than at
present. In string theory, if CP violation is described by a small parameter,
the axion may sit sufficiently close to its true minimum to invalidate the
bounds.Comment: 24 pages, uses harvmac. Refs corrected plus spellin
The signature of fine scale local adaptation in Atlantic salmon revealed from common garden experiments in nature
Understanding the extent, scale and genetic basis of local adaptation (LA) is important for conservation and management. Its relevance in salmonids at microgeographic scales, where dispersal (and hence potential gene flow) can be substantial, has however been questioned. Here, we compare the fitness of communally reared offspring of local and foreign Atlantic salmon Salmo salar from adjacent Irish rivers and reciprocal F-1 hybrid crosses between them, in the wild home\u27 environment of the local population. Experimental groups did not differ in wild smolt output but a catastrophic flood event may have limited our ability to detect freshwater performance differences, which were evident in a previous study. Foreign parr exhibited higher, and hybrids intermediate, emigration rates from the natal stream relative to local parr, consistent with genetically based behavioural differences. Adult return rates were lower for the foreign compared to the local group. Overall lifetime success of foreigners and hybrids relative to locals was estimated at 31% and 40% (mean of both hybrid groups), respectively. The results imply a genetic basis to fitness differences among populations separated by only 50km, driven largely by variation in smolt to adult return rates. Hence even if supplementary stocking programs obtain broodstock from neighbouring rivers, the risk of extrinsic outbreeding depression may be high
Genetic stock identification of Atlantic salmon (Salmo salar) populations in the southern part of the European range
notes: PMCID: PMC2882343© 2010 Griffiths 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.Anadromous migratory fish species such as Atlantic salmon (Salmo salar) have significant economic, cultural and ecological importance, but present a complex case for management and conservation due to the range of their migration. Atlantic salmon exist in rivers across the North Atlantic, returning to their river of birth with a high degree of accuracy; however, despite continuing efforts and improvements in in-river conservation, they are in steep decline across their range. Salmon from rivers across Europe migrate along similar routes, where they have, historically, been subject to commercial netting. This mixed stock exploitation has the potential to devastate weak and declining populations where they are exploited indiscriminately. Despite various tagging and marking studies, the effect of marine exploitation and the marine element of the salmon lifecycle in general, remain the "black-box" of salmon management. In a number of Pacific salmonid species and in several regions within the range of the Atlantic salmon, genetic stock identification and mixed stock analysis have been used successfully to quantify exploitation rates and identify the natal origins of fish outside their home waters - to date this has not been attempted for Atlantic salmon in the south of their European range.European Union INTERREG IIIB programme
(Atlantic Salmon Arc Project [ASAP], Project No. 040)
Cosmological Implications of Dynamical Supersymmetry Breaking
We provide a taxonomy of dynamical supersymmetry breaking theories, and
discuss the cosmological implications of the various types of models. Models in
which supersymmetry breaking is produced by chiral superfields which only have
interactions of gravitational strength (\eg\ string theory moduli) are
inconsistent with standard big bang nucleosynthesis unless the gravitino mass
is greater than \CO(3) \times 10^4 GeV. This problem cannot be solved by
inflation. Models in which supersymmetry is dynamically broken by
renormalizable interactions in flat space have no such cosmological problems.
Supersymmetry can be broken either in a hidden or the visible sector. However
hidden sector models suffer from several naturalness problems and have
difficulties in producing an acceptably large gluino mass.Comment: 24 pages (uses harvmac) UCSD/PTH 93-26, RU-3
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