921 research outputs found
Baryons in Partially-Quenched Chiral Perturbation Theory
I discuss the inclusion of baryons into partially-quenched chiral
perturbation theory and describe one-loop calculations that have been
performed.Comment: Lattice2002(matrixel) : talk presented at Lattice 2002, 7 page
Strange chiral nucleon form factors
We investigate the strange electric and magnetic form factors of the nucleon
in the framework of heavy baryon chiral perturbation theory to third order in
the chiral expansion. All counterterms can be fixed from data. In particular,
the two unknown singlet couplings can be deduced from the parity-violating
electron scattering experiments performed by the SAMPLE and the HAPPEX
collaborations. Within the given uncertainties, our analysis leads to a small
and positive electric strangeness radius, .
We also deduce the consequences for the upcoming MAMI A4 experiment.Comment: 7 pp, REVTeX, uses epsf, minor correction
Meaning in life and perceived quality of life in Switzerland: results of a representative survey in the German, French and Italian regions.
BACKGROUND: The concept of meaning in life (MIL) has become a central one in recent years, particularly in psycho-oncology and palliative care. The Schedule for Meaning in Life Evaluation (SMILE) has been developed to allow individuals to choose the life areas that they consider to be important for their own MIL. This approach relates to the "World Health Organisation" definition of quality of life (QOL) as an individual's perception of his own position. The aims of this study were (i) to assess MIL in a representative sample of the Swiss population according to the three linguistic regions and (ii) to evaluate whether MIL constitutes a significant determinant of the perceived QOL.
METHODS: A telephone survey of the Swiss population, performed by a professional survey company, was conducted between November and December 2013. The interview included the SMILE, perceived QOL (0-10) and health status (1-5), and various sociodemographic variables. In the SMILE, an index of weighting (IOW, 20-100), an index of satisfaction (IOS, 0-100), and a total SMILE index (IOWS, 0-100) are calculated from the areas mentioned by the participants as providing MIL.
RESULTS: Among the 6671 telephonic contacts realized, 1015 (15%) participants completed the survey: 405 French, 400 German and 210 Italian participants. "Family" (80.2%), "occupation/work" (51%), and "social relations" (43.3%) were the most cited MIL-relevant categories. Italian participants listed "health" more frequently than German and French participants (50.4% vs 31.5% and 24.8% respectively, Ï(2)â=â12.229, pâ=â.002). Age, gender, education, employment, and marital status significantly influenced either the MIL scores or the MIL-relevant categories. Linear regression analyses indicate that 24.3% of the QOL variance (pâ=â.000) is explained by health status (Bâ=â.609, ICâ=â.490-.728, pâ=â.000), MIL (Bâ=â.034, ICâ=â.028-.041, pâ=â.000) and socioeconomic status (Fâ=â11.01, pâ=â.000).
CONCLUSION: The major finding of our analysis highlights the positive and significant influence of MIL on the perceived QOL in a representative sample of a general, multilingual and multicultural population. This result indicates that the existential dimension is not only determinant for QOL in some critical life events, as shown e.g. in psycho-oncology and palliative care, but also in everyday life
The fossil record of early tetrapods: worker effort and the end-Permian mass extinction
It is important to understand the quality of the fossil record of early tetrapods (Tetrapoda, minus Lissamphibia and Amniota) because of their key role in the transition of vertebrates from water to land, their dominance of terrestrial faunas for over 100 million years of the late Palaeozoic and earlyMesozoic, and their variable fates during the endâPermian mass extinction. The first description of an early tetrapod dates back to 1824, and since then discoveries have occurred at a rather irregular pace, with peaks and troughs corresponding to some of the vicissitudes of human history through the past two centuries. As expected, the record is dominated by the wellâsampled sedimentary basins of Europe and North America, but finds from other continents are increasing rapidly. Comparisons of snapshots of knowledge in 1900, 1950, and 2000 show that discovery of new species has changed the shape of the speciesâlevel diversification curve, contrary to earlier studies of familyâlevel taxa. There is, however, little evidence that taxon counts relate to research effort (as counted by numbers of publications), and there are no biasing effects associated with differential study of different time intervals through the late Palaeozoic and Mesozoic. In fact, levels of effort are apparently not related to geological time, with no evidence that workers have spent more time on more recent parts of the record. In particular, the endâPermian mass extinction was investigated to determine whether diversity changes through that interval might reflect worker effort: it turns out that most records of early tetrapod taxa (when corrected for duration of geological series) occur in the Lower Triassic
Exact and moment equation modeling of electron transport in submicron structures
We compare IâVcharacteristics of a semiconducting submicron n + nn + diode as predicted by extended moment equation approximations to those obtained from the solution of the corresponding Boltzmann equation. All lower order models fail in the predominantly ballistic regime. Moreover, the conductance is inadequately predicted by these models, even in nonballistic cases due to the high buildâin electric fields
Thermocline management of stratified tanks for heat storage
Stratified tanks are useful for maximising the thermal energy efficiency of non-continuous and semi-continuous processes. Liquid at two or more dissimilar temperatures is stored within the same tank to provide a buffer for variations in heating and cooling loads. Control of the thermocline between the hot and cold fluid regions is needed to minimise thermocline growth and maximise operation of the storage tank. An experimental programme using a scale model of an industrial stratified tank (aspect ratio 3.5) and Perspex tank (aspect ratio 8.2) is reported. The behaviour and growth of the hot-cold thermocline under various operating conditions is presented. A siphoning method to re-establish the thermocline without interrupting the use of the tank is tested. Siphoning of the thermocline region from either 20%, 50% or 80% of the tank height is an effective strategy for uninterrupted interface re-establishment. However, the rate and position of siphoning and the load balance of the exit streams are critical variables for minimising the time for effective re-establishment of the two temperature zones
Chiral nonperturvative approach to the isoscalar s-wave pion-pion interaction in a nuclear medium
The s-wave isoscalar amplitude for pion-pion scattering in a nuclear medium
is evaluated using a nonperturbative unitary coupled channels method and the
standard chiral Lagrangians. The method has proved successful to describe the
pion-pion properties in the scalar isoscalar channel up to 1.2 GeV giving rise
to poles in the t matrix for the f0(980) and the sigma. The extension of the
method to the nuclear medium implies not only the renormalization of the pions
in the medium, but also the introduction of interaction terms related to
contact terms in the pion-nucleon to pion-pion-nucleon interaction. Off shell
effects are also shown to be important leading to cancellations which reduce
the coupled channel integral equations to a set of algebraic equations. As the
density increases we find a reduction of strength below the region and
a certain accumulation of strength at energies around pion threshold. Our
results, based on chiral Lagrangians, provide similar results to those obtained
with phenomenological models which impose minimal chiral constraints.Comment: 18 pages, LaTeX, 8 PostScript figures.(Revised version Aug-98, with
corrected results and new references
Baryon Decuplet to Octet Electromagnetic Transitions in Quenched and Partially Quenched Chiral Perturbation Theory
We calculate baryon decuplet to octet electromagnetic transition form factors
in quenched and partially quenched chiral perturbation theory. We work in the
isospin limit of SU(3) flavor, up to next-to-leading order in the chiral
expansion, and to leading order in the heavy baryon expansion. Our results are
necessary for proper extrapolation of lattice calculations of these
transitions. We also derive expressions for the case of SU(2) flavor away from
the isospin limit.Comment: 16 pages, 3 figures, revtex
Parity violating pion electroproduction off the nucleon
Parity violating (PV) contributions due to interference between and
exchange are calculated for pion electroproduction off the nucleon. A
phenomenological model with effective Lagrangians is used to determine the
resulting asymmetry for the energy region between threshold and
resonance. The resonance is treated as a Rarita-Schwinger field with
phenomenological transition currents. The background contributions
are given by the usual Born terms using the pseudovector Lagrangian.
Numerical results for the asymmetry are presented.Comment: 17 pages, RevTeX, 6 figures (in separate file figs.uu), uses epsf,
accepted for publication in Z. Phys.
Comparing powder magnetization and transport critical current of Bi,Pb(2223) tapes
The magnetic field dependence of the critical current in (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub 10+x/ tapes is compared with the magnetization response of isolated grains extracted from the tapes. Special attention is paid to the low-field behavior. The goal of the experiment is to test the widely-used hypothesis that current paths in these tapes contain both weak- and strong- linked branches, which in low field act in parallel. The data agree with this hypothesis; at temperatures above 50 K the powder magnetization drops off exponentially from the self-field to the irreversibility field, while the transport and magnetization currents in the intact tapes show an extra low-field component. Below 50 K the powder behavior becomes less straightforward, but the parallel-path picture in the tapes still holds
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