1,816 research outputs found
A Check of a D=4 Field-Theoretical Calculation Using the High-Temperature Expansion for Dyson's Hierarchical Model
We calculate the high-temperature expansion of the 2-point function up to
order 800 in beta. We show that estimations of the critical exponent gamma
based on asymptotic analysis are not very accurate in presence of confluent
logarithmic singularities. Using a direct comparison between the actual series
and the series obtained from a parametrization of the form (beta_c
-beta)^(-gamma) (Ln(beta_c -beta))^p +r), we show that the errors are minimized
for gamma =0.9997 and p=0.3351, in very good agreement with field-theoretical
calculations. We briefly discuss the related questions of triviality and
hyperscalingComment: Uses Revtex, 27 pages including 13 figure
Universality, Scaling and Triviality in a Hierarchical Field Theory
Using polynomial truncations of the Fourier transform of the RG
transformation of Dyson's hierarchical model, we show that it is possible to
calculate very accurately the renormalized quantities in the symmetric phase.
Numerical results regarding the corrections to the scaling laws, (i.e finite
cut-off dependence) triviality, hyperscaling, universality and high-accuracy
determinations of the critical exponents are discussed.Comment: LATTICE98(spin
High-Accuracy Calculations of the Critical Exponents of Dyson's Hierarchical Model
We calculate the critical exponent gamma of Dyson's hierarchical model by
direct fits of the zero momentum two-point function, calculated with an Ising
and a Landau-Ginzburg measure, and by linearization about the Koch-Wittwer
fixed point. We find gamma= 1.299140730159 plus or minus 10^(-12). We extract
three types of subleading corrections (in other words, a parametrization of the
way the two-point function depends on the cutoff) from the fits and check the
value of the first subleading exponent from the linearized procedure. We
suggest that all the non-universal quantities entering the subleading
corrections can be calculated systematically from the non-linear contributions
about the fixed point and that this procedure would provide an alternative way
to introduce the bare parameters in a field theory model.Comment: 15 pages, 9 figures, uses revte
Recent Changes in Irish Fertility. Quarterly Economic Commentary Special Article, May 1984
The main purpose of this paper is to provide a broad description of fertility
trends in Ireland over the last two decades. The analysis investigates in
particular whether there are regional (i.e., county) differences in relation to
the levels of fertility and how these have changed. In the final part of the paper
we discuss the likely future pattern of fertility trends and consider some
economic and social implications arising therefrom. The last-mentioned aspect
is now a matter of considerable significance since there are indications (from
the annual births total) that the general decline in fertility has escalated to
such an extent in recent years that the effects may be quite substantial and
materialise within a relatively short period of time
Some Remarks on the Pade Unitarization of Low-Energy Amplitudes
We present a critical analysis of Pade-based methods for the unitarization of
low energy amplitudes. We show that the use of certain Pade Approximants to
describe the resonance region may lead to inaccurate determinations. In
particular, we find that in the Linear Sigma Model the unitarization of the low
energy amplitude through the inverse amplitude method produces essentially
incorrect results for the mass and width of the sigma. Alternative sequences of
Pades are studied and we find that the diagonal sequences (i.e., [N/N]) have
much better convergence properties.Comment: 12 pages, 4 fig
Few-layer binder free graphene modified mercury film electrode for trace metal analysis by square wave anodic stripping voltammetry
A binding agent free graphene modified glassy carbon electrode in combination with an in situ plated mercury film electrode (Gr-GC-HgFE) was used as a highly sensitive electrochemical platform for the determination of Zn2+, Cd2+ and Pb2+ in 0.1 M acetate buffer (pH 4.6) by square-wave anodic stripping voltammetry (SWASV). Instrumental parameters such as deposition potential, deposition time and electrode rotation speed were optimized. The Gr-GC-HgFE sensing platform exhibited improved sensitivity for metal ion detection, in addition to well defined, reproducible and sharp stripping signals. Two linear calibration curves ranging from 0 â10 ÎŒg Lâ1 and 0 â 60 ÎŒg Lâ1 were identified yielding detection limits of 0.08 ÎŒg Lâ1, 0.05 ÎŒg Lâ1 and 0.14 ÎŒg Lâ1 for Zn2+, Cd2+ and Pb2+, respectively, for simultaneous analysis and 0.04 ÎŒg Lâ1, 0.11 ÎŒg Lâ1 and 0.14 ÎŒg Lâ1 for Zn2+, Cd2+ and Pb2+, respectively, for individual analysis when using a deposition time of 120 s. For practical applications recovery studies using tap water samples spiked with target metal ions gave recoveries within 10% of the spiked amount. Much better recoveries were obtained for the individual analysis in comparison with simultaneous analysis.Web of Scienc
Vector Meson Dominance as the first order of a sequence of Pade Approximants
The use of Pade Approximants for the analysis of the pion vector form-factor
is discussed and justified in this talk. The method is tested first in a
theoretical model and applied then on real experimental data. It is shown how
the Pade Approximants provide a convenient and reliable framework to
incorporate both low and high energy information in the euclidean region,
leading to improved determinations of the low energy parameters such as, e.g.,
the quadratic radius ^pi_V.Comment: 4 pages, 3 figures, espcrc2 style. To appear in the proceedings of
the 14th International QCD Conference, QCD 08, 7-12 July 2008, Montpellier
(France
Contestable adulthood: variability and disparity in markers for negotiating the transition to adulthood
Recent research has identified a discreet set of subjective markers that are seen as characterizing the transition to adulthood. The current study challenges this coherence by examining the disparity and variability in young peopleâs selection of such criteria. Four sentence-completion cues corresponding to four differentcontexts in which adult status might be contested were given to 156 British 16- to 17-year-olds. Their qualitative responses were analyzed to
explore patterns whilst capturing some of their richness and diversity. An astonishing amount of variability emerged, both within and between cued contexts.The implications of this variability for how the transition to adulthood is experienced are explored. The argument is made that markers of the transition to adulthood are not merely reflective of the bioâpsychoâsocial development of
young people. Rather, adulthood here is seen as an essentially contested concept,located within the discursive interactional environment in which young people participate
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