Impact of the symmetry energy on the outer crust of non-accreting neutron stars

The composition and equation of state of the outer crust of non-accreting neutron stars is computed using accurate nuclear mass tables. The main goal of the present study is to understand the impact of the symmetry energy on the structure of the outer crust. First, a simple "toy model" is developed to illustrate the competition between the electronic density and the symmetry energy. Then, realistic mass tables are used to show that models with a stiff symmetry energy - those that generate large neutron skins for heavy nuclei - predict a sequence of nuclei that are more neutron-rich than their softer counterparts. This result may be phrased in the form of a correlation: the larger the neutron skin of 208Pb, the more exotic the composition of the outer crust.Comment: 21 pages, 8 figures, submitted to Physical Review

CTQ 414: A New Gravitational Lens

We report the discovery and ground based observations of the new gravitational lens CTQ 414. The source quasar lies at a redshift of z = 1.29 with a B magnitude of 17.6. Ground based optical imaging reveals two point sources separated by 1.2 arcsec with a magnitude difference of roughly 1 mag. Subtraction of two stellar point spread functions from images obtained in subarcsecond seeing consistently leaves behind a faint, residual object. Fits for two point sources plus an extended object places the fainter object collinear with the two brighter components. Subsequent HST/NICMOS observations have confirmed the identification of the fainter object as the lensing galaxy. VLA observations at 8.46 GHz reveal that all components of the lensing system are radio quiet down to the 0.2 mJy flux level.Comment: Latex, 18 pages including 2 ps figures; accepted for publication in A

On Hardy kernels as reproducing kernels

Hardy kernels are a useful tool to define integral operators on Hilbertian spaces like L2 (R+) or H2 (C+). These kernels entail an algebraic L1-structure which is used in this work to study the range spaces of those operators as reproducing kernel Hilbert spaces. We obtain their reproducing kernels, which in the H2 (R+) case turn out to be Hardy kernels as well. In the H2 (C+) scenario, the reproducing kernels are given by holomorphic extensions of Hardy kernels. Other results presented here are theorems of Paley-Wiener type, and a connection with one-sided Hilbert transforms

Asset Booms and Tax Receipts: The case of Spain, 1995-2006

At about 3¾% for more than 10 years in a row, Spain is enjoying the longest period of sustained growth above the euro area since the late sixties. This period is also characterised by a combination of persistently low real interest rates and a dynamic demography, which has been feeding unprecedented growth in asset markets. In parallel, total-tax receipts have grown by about 4¼ percentage points of GDP, thus recording an elasticity with respect to GDP of 1.2. This paper discusses and assesses the extent to which the increase in tax receipts can be associated to changes in the composition of GDP, which would fade out after the current expansion tapers off. Econometric analyses provide evidence that 50 to 75 percent of the increase in tax revenues, observed in Spain between 1995 and 2006, might be of a transitory nature and would disappear with the asset boom. On this basis, in a context of significant composition effects, using standard tax elasticities may lead to an overestimation of structural revenues and to an incorrect assessment of the fiscal stance. This may be relevant in EMU because the likelihood of occurrence of asset booms may be relatively high when the monetary-policy stance is far from consistent with the country's inflation. Furthermore, in the specific case of Spain, the size of transitory composition effects associated to the current asset boom highlights the interest for the policymakers of the country to carefully assess the implementation of unfunded tax cuts and/or expenditure increases, especially those more difficult to revert in bad times.Fiscal policies, tax revenues, deficits, asset prices, composition effects, Spain, Martinez-Mongay, Maza Lasierra, Yaniz Igal

Unjamming a granular hopper by vibration

We present an experimental study of the outflow of a hopper continuously vibrated by a piezoelectric device. Outpouring of grains can be achieved for apertures much below the usual jamming limit observed for non vibrated hoppers. Granular flow persists down to the physical limit of one grain diameter, a limit reached for a finite vibration amplitude. For the smaller orifices, we observe an intermittent regime characterized by alternated periods of flow and blockage. Vibrations do not significantly modify the flow rates both in the continuous and the intermittent regime. The analysis of the statistical features of the flowing regime shows that the flow time significantly increases with the vibration amplitude. However, at low vibration amplitude and small orifice sizes, the jamming time distribution displays an anomalous statistics

Bernstein-Szego Polynomials Associated with Root Systems

We introduce multivariate generalizations of the Bernstein-Szego polynomials, which are associated to the root systems of the complex simple Lie algebras. The multivariate polynomials in question generalize Macdonald's Hall-Littlewood polynomials associated with root systems. For the root system of type A1 (corresponding to the Lie algebra SL (2;C)) the classic Bernstein-Szego polynomials are recovered.Comment: LaTeX, 12 page