Chiral two-loop pion-pion scattering parameters from crossing-symmetric constraints

Constraints on the parameters in the one- and two-loop pion-pion scattering amplitudes of standard chiral perturbation theory are obtained from explicitly crossing-symmetric sum rules. These constraints are based on a matching of the chiral amplitudes and the physical amplitudes at the symmetry point of the Mandelstam plane. The integrals over absorptive parts appearing in the sum rules are decomposed into crossing-symmetric low- and high-energy components and the chiral parameters are finally related to high-energy absorptive parts. A first application uses a simple model of these absorptive parts. The sensitivity of the results to the choice of the energy separating high and low energies is examined with care. Weak dependence on this energy is obtained as long as it stays below ~560 MeV. Reliable predictions are obtained for three two-loop parameters.Comment: 23 pages, 4 figures in .eps files, Latex (RevTex), our version of RevTex runs under Latex2.09, submitted to Phys. Rev. D,minor typographical corrections including the number at the end of the abstract, two sentences added at the end of Section 5 in answer to a referee's remar

Optical Continuum and Emission-Line Variability of Seyfert 1 Galaxies

We present the light curves obtained during an eight-year program of optical spectroscopic monitoring of nine Seyfert 1 galaxies: 3C 120, Akn 120, Mrk 79, Mrk 110, Mrk 335, Mrk 509, Mrk 590, Mrk 704, and Mrk 817. All objects show significant variability in both the continuum and emission-line fluxes. We use cross-correlation analysis to derive the sizes of the broad Hbeta-emitting regions based on emission-line time delays, or lags. We successfully measure time delays for eight of the nine sources, and find values ranging from about two weeks to a little over two months. Combining the measured lags and widths of the variable parts of the emission lines allows us to make virial mass estimates for the active nucleus in each galaxy. The virial masses are in the range 10^{7-8} solar masses.Comment: 24 pages, 16 figures. Accepted for publication in Ap

Perceived thickness and creaminess modulates the short-term satiating effects of high protein drinks

Previous research suggests that increasing beverage protein content enhances subsequent satiety, but whether this effect is entirely attributable to post-ingestive effects of protein or is partly caused by the distinct sensory characteristics imparted by the presence of protein remains unclear. To try and discriminate nutritive from sensory effects of added protein, we contrasted effects of three higher energy (c. 1.2MJ) and one lower energy (LE: 0.35MJ) drink preloads on subsequent appetite and lunch intake. Two higher energy drinks had 44% of energy from protein, one with the sensory characteristics of a juice drink (HP-) and the second thicker and more creamy (HP+). The high-carbohydrate preload (HC+) was matched for thickness and creaminess to the HP+ drink. Participants (healthy male volunteers, n=26) consumed significantly less at lunch after the HP+ (566g) and HC+ (572g) than after HP- (623g) and LE (668g) drinks, although the compensation for drink energy accounted for only 50% of extra energy at best. Appetite ratings indicated that participants felt significantly less hungry and more full immediately before lunch in HP+ and HC+ compared to LE, with HP- intermediate. The finding that protein generated stronger satiety in the context of a thicker creamier drink (HP+ but not HP-), and that an isoenergetic carbohydrate drink (HC+) matched in thickness and creaminess to the HP+ drink generated the same pattern of satiety as HP+ both suggest an important role for these sensory cues in the development of protein-based satiety

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency

A new case of 3-hydroxyacyl-CoA dehydrogenase deficiency is described with a relatively benign course

The Use of Nonparametric Item Response Theory to Explore Data Quality

The aim of this chapter is to provide insight into a number of commonly used nonparametric item response theory (NIRT) methods and to show how these methods can be used to describe and explore the psychometric quality of questionnaires used in patient-reported outcome measurement and, more in general, typical performance measurement (personality, mood, health-related constructs). NIRT is an extremely valuable tool for preliminary data analysis and for evaluating whether item response data are acceptable for parametric IRT modeling. This is in particular useful in the field of typical performance measurement where the construct being measured is often very different than in maximum performance measurement (education, intelligence; see Chapter 1 of this handbook). Our basic premise is that there are no “best tools” or “best models” and that the usefulness of psychometric modeling depends on the specific aims of the instrument (questionnaire, test) that is being used. Most important is, however, that it should be clear for a researcher how sensitive a specific method (for example, DETECT, or Mokken scaling) is to the assumptions that are being investigated. The NIRT literature is not always clear about this, and in this chapter we try to clarify some of these ambiguities

Magnetic Confinement, MHD Waves, and Smooth Line Profiles in AGN

In this paper, we show that if the broad line region clouds are in approximate energy equipartition between the magnetic field and gravity, as hypothesized by Rees, there will be a significant effect on the shape and smoothness of broad emission line profiles in active galactic nuclei. Line widths of contributing clouds or flow elements are much wider than their thermal widths, due to the presence of non-dissipative MHD waves, and their collective contribution produce emission line profiles broader and smoother than would be expected if a magnetic field were not present. As an illustration, a simple model of isotropically emitting clouds, normally distributed in velocity, is used to show that smoothness can be achieved for less than 80,000 clouds and may even be as low as a few hundred. We conclude that magnetic confinement has far reaching consequences for observing and modeling active galactic nuclei.Comment: to appear in MNRA

Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database

We present improved black hole masses for 35 active galactic nuclei (AGNs) based on a complete and consistent reanalysis of broad emission-line reverberation-mapping data. From objects with multiple line measurements, we find that the highest precision measure of the virial product is obtained by using the cross-correlation function centroid (as opposed to the cross-correlation function peak) for the time delay and the line dispersion (as opposed to full width half maximum) for the line width and by measuring the line width in the variable part of the spectrum. Accurate line-width measurement depends critically on avoiding contaminating features, in particular the narrow components of the emission lines. We find that the precision (or random component of the error) of reverberation-based black hole mass measurements is typically around 30%, comparable to the precision attained in measurement of black hole masses in quiescent galaxies by gas or stellar dynamical methods. Based on results presented in a companion paper by Onken et al., we provide a zero-point calibration for the reverberation-based black hole mass scale by using the relationship between black hole mass and host-galaxy bulge velocity dispersion. The scatter around this relationship implies that the typical systematic uncertainties in reverberation-based black hole masses are smaller than a factor of three. We present a preliminary version of a mass-luminosity relationship that is much better defined than any previous attempt. Scatter about the mass-luminosity relationship for these AGNs appears to be real and could be correlated with either Eddington ratio or object inclination.Comment: 61 pages, including 8 Tables and 16 Figures. Accepted for publication in The Astrophysical Journa