Exceptional solutions to the eight-vertex model and integrability of anisotropic extensions of massive fermionic models

We consider several anisotropic extensions of the Belavin model, and show that integrability holds also for the massive case for some specific relations between the coupling constants. This is done by relating the S-matrix factorization property to the exceptional solutions of the eight-vertex model. The relation of exceptional solutions to the XXZ and six-vertex models is also shown

Elucidating the multiplicity dependence of J/ψ\psi production in proton-proton collisions with PYTHIA8

A study of prompt and non-prompt J/$\psi$ production as a function of charged-particle multiplicity in inelastic proton--proton (pp) collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV based on calculations using the PYTHIA8 Monte Carlo is reported. Recent experimental data shows an intriguing stronger-than-linear increase of the self-normalized J/$\psi$ yield with multiplicity; several models, based on initial or final state effects, have been able to describe the observed behaviour. In this paper, the microscopic reasons for this behaviour, like the role of multiple parton interactions, colour reconnections and auto-correlations are investigated. It is observed that the stronger-than-linear increase and the transverse momentum ($p_{\rm T}$) dependence, contrary to what is predicted by the other available models, can be attributed to auto-correlation effects only. In absence of auto-correlation effects, the increase of the yield of J/$\psi$ with multiplicity -- and in general for all hard processes -- is weaker than linear for multiplicities exceeding about three times the mean multiplicity. The possibility of disentangling auto-correlation effects from other physical phenomena by measuring the charged-particle multiplicity in different pseudo-rapidity and azimuthal regions relative to the J/$\psi$ direction is investigated. In this regard, it is suggested to extend the experimental measurements of J/$\psi$ production as a function of the charged-particle multiplicity by determining the multiplicity in several azimuthal regions and in particular in the Transverse region with respect to the direction of the J/$\psi$ meson.Comment: 12 pages, 14 figures: accepted by EPJ

Anti-solar differential rotation on the active sub-giant HU Virginis

Measuring surface differential rotation (DR) on different types of stars is important when characterizing the underlying stellar dynamo. It has been suggested that anti-solar DR laws can occur when strong meridional flows exist. We aim to investigate the differential surface rotation on the primary star of the RS CVn binary HU Vir by tracking its starspot distribution as a function of time. We also aim to recompute and update the values for several system parameters of the triple system HU Vir (close and wide orbits). Time-series high-resolution spectroscopy for four continuous months was obtained with the 1.2-m robotic STELLA telescope. Nine consecutive Doppler images were reconstructed from these data, using our line-profile inversion code iMap. An image cross-correlation method was applied to derive the surface differential-rotation law for HU Vir. New orbital elements for the close and the wide orbits were computed using our new STELLA radial velocities (RVs) combined with the RV data available in the literature. Photometric observations were performed with the Amadeus Automatic Photoelectric Telescope (APT), providing contemporaneous Johnson-Cousins $V$ and $I$ data for approximately 20 years. This data was used to determine the stellar rotation period and the active longitudes. We confirm anti-solar DR with a surface shear parameter $\alpha$ of -0.029 $\pm$ 0.005 and -0.026 $\pm$ 0.009, using single-term and double-term differential rotation laws, respectively. The best fit is achieved assuming a solar-like double-term law with a lap time of $\approx$ 400 d. Our orbital solutions result in a period of 10.387678 $\pm$ 0.000003 days for the close orbit and 2726 $\pm$ 7 d ($\approx$ 7.5 yr) for the wide orbit. A Lomb-Scarge (L-S) periodogram of the pre-whitened $V$-band data reveals a strong single peak providing a rotation period of 10.391 $\pm$ 0.008 d.Comment: Accepted for publication in A&

DOES ECONOMIC VULNERABILITY DEPEND ON PLACE OF RESIDENCE? ASSET POVERTY ACROSS THE RURAL-URBAN CONTINUUM

This paper uses Panel Study of Income Dynamics data for 1989, 1994, and 1999 to examine why some U.S. households are asset poor; that is, why households have insufficient resources to invest in their future or to sustain household members at a basic level during times of economic disruption. The study contributes to an improved understanding of asset poverty's correlates by examining the influence of place of residence; the extant literature has focused on individual-level explanations. We estimate a random-effects logistic model of the probability that an individual is asset poor at a given point in time as a function of household-level (e.g. age, gender, race of the household head and family structure) and place-level (regional and rural-urban continuum) variables. The central finding of the paper is that place of residence is an important determinant of asset poverty, above and beyond the influence of household characteristics. We find that living in a central metropolitan county and in a nonmetropolitan area is associated with a higher risk of being asset poor, all else being equal. Implications for future research are discussed.Food Security and Poverty,

Performance characteristics of wind profiling radars

Doppler radars used to measure winds in the troposphere and lower stratosphere for weather analysis and forecasting are lower-sensitivity versions of mesosphere-stratosphere-troposphere radars widely used for research. The term wind profiler is used to denote these radars because measurements of vertical profiles of horizontal and vertical wind are their primary function. It is clear that wind profilers will be in widespread use within five years: procurement of a network of 30 wind profilers is underway. The Wave Propagation Laboratory (WPL) has operated a small research network of radar wind profilers in Colorado for about two and one-half years. The transmitted power and antenna aperture for these radars is given. Data archiving procedures have been in place for about one year, and this data base is used to evaluate the performance of the radars. One of the prime concerns of potential wind profilers users is how often and how long wind measurements are lacking at a given height. Since these outages constitute an important part of the performance of the wind profilers, they are calculated at three radar frequencies, 50-, 405-, and 915-MHz, (wavelengths of 6-, 0.74-, and 0.33-m) at monthly intervals to determine both the number of outages at each frequency and annual variations in outages