17,780 research outputs found

    Diets of shags Phalacrocorax aristotelis and cormorants P. carbo in Norway and possible implications for gadoid stock recruitment

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    The diets of shags and cormorants were studied in Norway through analyses of regurgitated pellets. Although this method has many limitations, indications were that both species rely heavily on small gadoids (Gadidae) and sand eels (Ammodytidae) for food throughout their range, but also eat other fish species when available. There was considerable dietary overlap between species, despite a tendency for cormorants to eat larger fish and more benthic items than shags. Predation by shags and cormorants could be a factor limiting the recruitment of cod and saithe into what are now severely reduced, but commercially important stocks in the Norwegian and Barents Seas

    Efficient quantum key distribution secure against no-signalling eavesdroppers

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    By carrying out measurements on entangled states, two parties can generate a secret key which is secure not only against an eavesdropper bound by the laws of quantum mechanics, but also against a hypothetical "post-quantum" eavesdroppers limited by the no-signalling principle only. We introduce a family of quantum key distribution protocols of this type, which are more efficient than previous ones, both in terms of key rate and noise resistance. Interestingly, the best protocols involve large number of measurements. We show that in the absence of noise, these protocols can yield one secret bit per entanglement bit, implying that the key rates in the no-signalling post-quantum scenario are comparable to the key rates in usual quantum key distribution.Comment: 11 pages, 2 color figures. v2: minor modifications, added references, added note on the relation to quant-ph/060604

    Fuel poverty, older people and cold weather: An all-island analysis

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    Executive Summary This report covers a number of different aspects of fuel poverty and older people. 1. An exploration of existing government survey data from Northern Ireland and the Republic of Ireland with a particular focus on older people and conducting additional targeted analyses where required. 2. An original survey in the Republic of Ireland exploring the lived experience of older people in cold weather. 3. A feasibility study of data logging thermometers placed in the homes of older tenants in local authority accommodation. 4. Analysis of excess winter mortality among older people including a consideration of differences between the two jurisdictions. Older people on the island of Ireland, as in many other countries, experience a ‘dual burden’ in terms of fuel poverty. They are more likely to experience fuel poverty and are also particularly vulnerable to health and social harm as a result of this experience. The numbers of older people vulnerable to ill-effects from cold homes will rise as numbers of people aged 80 and over, and those living with chronic illness or disability, increase. There were significant differences observed between expenditure-based, and subjective (EU-SILC) based fuel poverty indicators, for older people, and between Northern Ireland and Republic of Ireland data. This data required careful interpretation. The higher levels of fuel poverty recorded for older people on the island of Ireland appeared to be driven by all aspects of the fuel poverty model - poor housing condition, energy inefficient housing, rising fuel prices and low income. The majority of older people live in their own home and these homes tend to be older properties which are detached or semi-detached. Older people on the island are over-represented among houses which are in poor condition and which lack central heating in both jurisdictions. Lacking central heating was a more common experience for older people in the Republic of Ireland than in Northern Ireland. Data on energy efficiency measures were not comparable North/South but similar patterns were observed. Older people were less likely than the general population to have attic/loft or wall insulation or double glazing. Older people were also vulnerable from an income point of view. This would seem to be a particular issue in Northern Ireland where rates of income poverty are significantly increasing. In both jurisdictions older people were heavily reliant on social transfers to keep them out of poverty. Coupled with this, there is evidence that many older people are not claiming their full entitlements. Oil dependency was a particular issue in Northern Ireland. Very significant increases were observed in the price of heating oil, as well as electricity and gas in recent years. There was little available research evidence on the relationship between the older consumer and heating oil suppliers

    The rationale for energy efficiency policy: Assessing the recognition of the multiple benefits of energy efficiency retrofit policy

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    The rationale for energy efficiency policy can be framed in terms of a variety of different benefits. This paper considers how different benefits have been used within the overall rationale for energy efficient retrofit policy in different contexts. We posit that different rationales may be used for the same policy response, and that the form of rationale used may affect the design, delivery or the level of policy support, with different rationales making it easier to account for different results. Considering retrofit policy in the contexts of the UK, Germany, New Zealand and Ireland, we characterise policy rationale in each case, assessing what the key perceived benefits have been, and whether they have changed over time. The analysis identifies some marked differences between cases with the recognition of benefits and the ensuing policy rationale resulting from a complex mix of political, social and economic influences. We find that recognition of multiple benefits may not equate with multiplied policy support, and instead it is more likely that different rationales will have relevance at different times, for different audiences. The findings highlight that, alongside evidence for policy, it is important to also consider how the overall rationale for policy is eventually framed

    Nonsequential positive-operator-valued measurements on entangled mixed states do not always violate a Bell inequality

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    We present a local-hidden-variable model for positive-operator-valued measurements (an LHVPOV model) on a class of entangled generalized Werner states, thus demonstrating that such measurements do not always violate a Bell-type inequality. We also show that, in general, if the state ρ\rho' can be obtained from ρ\rho with certainty by local quantum operations without classical communication then an LHVPOV model for the state ρ\rho implies the existence of such a model for ρ\rho'.Comment: 4 pages, no figures. Title changed to accord with Phys. Rev. A version. Journal reference adde

    On the Expansions in Spin Foam Cosmology

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    We discuss the expansions used in spin foam cosmology. We point out that already at the one vertex level arbitrarily complicated amplitudes contribute, and discuss the geometric asymptotics of the five simplest ones. We discuss what type of consistency conditions would be required to control the expansion. We show that the factorisation of the amplitude originally considered is best interpreted in topological terms. We then consider the next higher term in the graph expansion. We demonstrate the tension between the truncation to small graphs and going to the homogeneous sector, and conclude that it is necessary to truncate the dynamics as well.Comment: 17 pages, 4 figures, published versio

    Study of the ground-state energy of 40Ca with the CD-Bonn nucleon-nucleon potential

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    We have calculated the ground-state energy of the doubly-magic nucleus 40Ca within the framework of the Goldstone expansion using the CD-Bonn nucleon-nucleon potential. The short-range repulsion of this potential has been renormalized by integrating out its high-momentum components so as to derive a low-momentum potential V-low-k defined up to a cutoff momentum Lambda. A simple criterion has been employed to establish a connection between this cutoff momentum and the size of the two-nucleon model space in the harmonic oscillator basis. This model-space truncation approach provides a reliable way to renormalize the free nucleon-nucleon potential preserving its many-body physics. The role of the 3p-3h and 4p-4h excitations in the description of the ground state of 40Ca is discussed.Comment: 4 pages, 1 figure, 1 table, to be published in Physical Review

    Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner-Wadsworth-Emmons-based approach

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    Integrin inhibitors based on the tripeptide sequence Arg-Gly-Asp (RGD) are potential therapeutics for the treatment of idiopathic pulmonary fibrosis (IPF). Herein, we describe an expeditious three-step synthetic sequence of Horner-Wadsworth-Emmons olefination, diimide reduction, and global deprotection to synthesise cores for these compounds in high yields (63-83% over 3 steps) with no need for chromatography. Key to this transformation is the phosphoramidate protecting group, which is stable to metalation steps
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