7 research outputs found
The nuclear energy density functional formalism
The present document focuses on the theoretical foundations of the nuclear
energy density functional (EDF) method. As such, it does not aim at reviewing
the status of the field, at covering all possible ramifications of the approach
or at presenting recent achievements and applications. The objective is to
provide a modern account of the nuclear EDF formalism that is at variance with
traditional presentations that rely, at one point or another, on a {\it
Hamiltonian-based} picture. The latter is not general enough to encompass what
the nuclear EDF method represents as of today. Specifically, the traditional
Hamiltonian-based picture does not allow one to grasp the difficulties
associated with the fact that currently available parametrizations of the
energy kernel at play in the method do not derive from a genuine
Hamilton operator, would the latter be effective. The method is formulated from
the outset through the most general multi-reference, i.e. beyond mean-field,
implementation such that the single-reference, i.e. "mean-field", derives as a
particular case. As such, a key point of the presentation provided here is to
demonstrate that the multi-reference EDF method can indeed be formulated in a
{\it mathematically} meaningful fashion even if does {\it not} derive
from a genuine Hamilton operator. In particular, the restoration of symmetries
can be entirely formulated without making {\it any} reference to a projected
state, i.e. within a genuine EDF framework. However, and as is illustrated in
the present document, a mathematically meaningful formulation does not
guarantee that the formalism is sound from a {\it physical} standpoint. The
price at which the latter can be enforced as well in the future is eventually
alluded to.Comment: 64 pages, 8 figures, submitted to Euroschool Lecture Notes in Physics
Vol.IV, Christoph Scheidenberger and Marek Pfutzner editor
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
Nutritional screening and assessment tools for older adults: literature review
Aim: This paper reports a literature review to examine the range of published tools available for use by nurses to screen or assess nutritional status of older adults, and the extent to which validity, reliability, sensitivity, specificity and acceptability of the tools has been addressed.
Background: The incidence of malnutrition in older adults is high. One method by which malnutrition or risk of malnutrition can be detected is by the use of nutritional screening or assessment tools.
Methods: A comprehensive literature review methodology was employed. A variety of electronic databases were searched for the period 1982-2002. Search terms incorporating nutrition, screening, validity, reliability and sensitivity and specificity were combined to retrieve relevant literature. In addition, manual searches were conducted and articles retrieved from those listed in key papers. In this paper, nutritional screening or assessment tools are described as tools which use a questionnaire-type format containing more than one risk factor for malnutrition, and give a quantitative or categorical assessment of risk.
Results: Seventy-one nutritional tools were located, 21 of which were identified as designated for use with an older population. A wide variety of risk factors for malnutrition are used with the tools, ranging from objective measurements to subjective assessment. Some tools identify an action plan based on the score obtained. Many tools appear not to have been subjected to validity and/or reliability testing but are used clinically.
Conclusion: As malnutrition is present in the older adult population, nutritional assessment and screening tools can be useful to highlight those in need of a nutritional care plan. However, many have not been subjected to evaluation and consequently may not demonstrate sensitivity and/or specificity in clinical use. The decision to use a particular tool should therefore be considered carefully
Nutritional screening and assessment tools for use by nurses: literature review
Aim.? This paper reports a literature review describing the range of published tools available for use by nurses to screen or assess nutritional status of patients/clients, and to examine whether the validity, reliability, sensitivity, specificity and acceptability of the tool have been investigated. Tools developed specifically for use with older adults are not considered in this review. A screening/assessment tool is described as a tool that uses a questionnaire-type format, contains more than one risk factor for malnutrition and gives an assessment of risk.Background.? The incidence of malnutrition in people cared for by nurses is high and screening or assessment tools are often used to identify those with, or at risk of, malnutrition.Methods.? A comprehensive literature review methodology was employed. A range of electronic databases was searched from 1982 to 2002. Search terms incorporating ‘nutrition’, ‘screening’, assessment, feeding, instrument, tool, validity, reliability, sensitivity and specificity were combined. Manual searches were also conducted.Results.? Seventy-one nutritional screening/assessment tools were identified of which 35 were reviewed. Tools not reviewed included those which incorporated significant use of biochemical measures (8), included complex anthropometric measures (3), were concerned specifically with ingestion (4) or were designated for use with an older population (21). The tools reviewed use a wide variety of risk factors for malnutrition, varying from anthropometric measurements to socio-cultural aspects of eating behaviour. Some identify an action plan based on the score obtained. Many have not been subjected to validity and/or reliability testing and yet appear to be in use in clinical practice. The sensitivity, specificity and acceptability of the tools are often not investigated.Conclusion.? There are many published nutritional screening/assessment tools available for use by nurses to screen or assess the nutritional status of patients/clients. Many have not been subject to rigorous testing. Future work should consider a more standardized approach to the use of these tools
Grazing and ecosystem service delivery in global drylands
Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure