14,556 research outputs found
Polarized Double Photon Production in QCD to Order
We present a complete order analysis of the process with polarized initial states, previously studied by us with
leading order structure functions. We include in our calculation new sets of
parton densities evolved in NLO QCD, such as those of Gehrmann and Stirling and
of Gl\"{u}ck et al., which incorporate the new anomalous dimensions of Mertig
and Van Neerven in the evolution equation. A detailed phenomenological analysis
is also given which includes the photon isolation. Our results indicate that
the asymmetries, although not very large, should be substantial enough at RHIC
energies to be measurable in future planned experiments.Comment: 29 pages revtex, 13 psfig
Cross-validation of the reduced form of the food craving questionnaire -trait using confirmatory factor analysis
Objective: The Food Craving Questionnaire-Trait (FCQ-T) is commonly used to assess habitual food cravings among individuals. Previous studies have shown that a brief version of this instrument (FCQ-T-r) has good reliability and validity. This article is the first to use Confirmatory factor analysis to examine the psychometric properties of the FCQ-T-r in a cross-validation study.
Method: Habitual food cravings, as well as emotion regulation strategies, affective states, and disordered eating behaviors, were investigated in two independent samples of non-clinical adult volunteers (Sample 1: N = 368; Sample 2: N = 246). Confirmatory factor analyses were conducted to simultaneously test model fit statistics and dimensionality of the instrument. FCQ-T-r reliability was assessed by computing the composite reliability coefficient.
Results: Analysis supported the unidimensional structure of the scale and fit indices were acceptable for both samples. The FCQ-T-r showed excellent reliability and moderate to high correlations with negative affect and disordered eating.
Conclusion: Our results indicate that the FCQ-T-r scores can be reliably used to assess habitual cravings in an Italian non-clinical sample of adults. The robustness of these results is tested by a cross-validation of the model using two independent samples. Further research is required to expand on these findings, particularly in children and adolescents
On the Flow Curve of Colloids Presenting Shear-Induced Phase Transitions
This work deals with the evaluation of the flow curve of colloidal systems
that develop fluid phases with different mechanical properties, namely
shear-banding fluids. The problem involved is that, as different fluid phases
coexist in the flow domain of the rheometric cell, measured data cannot be
directly converted into rheometric functions. In order to handle this problem,
a shear stress vs. shear rate constitutive relation is introduced to interpret
the steady state flow curves. The relation derives from a phenomenological
description of structural changes, and involves the possibility of multivalued
shear rates under a given shear stress. Numerical predictions satisfactorily
match up to experimental data of wormlike micellar solutions. A crucial aspect
is the adequate computation of the shear rate function from raw data measured
in the rheometric cell.Comment: 12 page
Magnetic Monopoles in Spin Ice
Electrically charged particles, such as the electron, are ubiquitous. By
contrast, no elementary particles with a net magnetic charge have ever been
observed, despite intensive and prolonged searches. We pursue an alternative
strategy, namely that of realising them not as elementary but rather as
emergent particles, i.e., as manifestations of the correlations present in a
strongly interacting many-body system. The most prominent examples of emergent
quasiparticles are the ones with fractional electric charge e/3 in quantum Hall
physics. Here we show that magnetic monopoles do emerge in a class of exotic
magnets known collectively as spin ice: the dipole moment of the underlying
electronic degrees of freedom fractionalises into monopoles. This enables us to
account for a mysterious phase transition observed experimentally in spin ice
in a magnetic field, which is a liquid-gas transition of the magnetic
monopoles. These monopoles can also be detected by other means, e.g., in an
experiment modelled after the celebrated Stanford magnetic monopole search.Comment: (6 pages, 6 figures) v2: fig 3 replaced with colour version. For the
high-definition version of the paper click
http://www-thphys.physics.ox.ac.uk/user/ClaudioCastelnovo/Publications/papersub.pd
Deconstructing herding : evidence from pension fund investment behavior
Pension funds have been expected to invest in a wide range of securities and provide liquidity to domestic capital markets since they are the most sophisticated investors, with plenty of resources to gather private information and manage portfolios professionally. However, by analyzing unique, monthly asset-level data from the pioneer case of Chile, this paper shows that pension funds tend to herd. This is consistent with pension funds copying each other in their investment strategies as a way to extract information, boost returns, and reduce risk. The authors compute measures of herding across asset classes (equities, government bonds, and private sector bonds) and at different pension fund industry levels. The results show that pension funds herd more in assets for which they have less market information and when risk increases. Moreover, herding is more prevalent across funds that narrowly compete with each other, that is, when comparing funds of the same type across pension fund administrators. There is much less herding within pension fund administrators and across pension fund administrators as a whole. This herding pattern is consistent with incentives for managers to be close to industry benchmarks, which might be driven by both market forces and regulation.Debt Markets,Mutual Funds,Emerging Markets,Investment and Investment Climate,Economic Theory&Research
- …