Construction of Nonlinear Symplectic Six-Dimensional Thin-Lens Maps by Exponentiation

The aim of this paper is to construct six-dimensional symplectic thin-lens transport maps for the tracking program SIXTRACK, continuing an earlier report by using another method which consistes in applying Lie series and exponentiation as described by W. Groebner and for canonical systems by A.J. Dragt. We firstly use an approximate Hamiltonian obtained by a series expansion of the square root. Furthermore, nonlinear crossing terms due to the curvature in bending magnets are neglected. An improved Hamiltonian, excluding solenoids, is introduced in Appendix A by using the unexpanded square root mentioned above, but neglecting again nonlinear crossing terms...Comment: 57 pages, late

Religion and the shadow economy

Religion is increasingly acknowledged to be a cultural dimension which affects economic outcomes in different regards. This contribution focuses on religion's possible impact on the shadow economy. Different dimensions of the religious markets are taken into account. These dimensions refer to the overall degree of religiosity, the specific impact of different religions, religious competition or the proximity between religion and the state. The empirical test makes use of the largest available cross-section on the size of the shadow economy and matches this dataset with numerous religious indicators. Summary measures of general religiosity or indicators of religious competition do not have a measurable impact. However, robust differences emerge across religions. Countries dominated by Islam or Eastern religions are associated with smaller shadow economies compared to Christian countries. Furthermore, the proximity between state and religion matters. Close ties between both are typical for smaller shadow economies. This is in line with the view that religion uses its normative influence to protect state interests if there is a mutually beneficial relationship. --Economics of religion,tax morale,shadow economy

Tax compliance under tax regime changes

In this paper we focus on the compliance effects of tax regime changes. According to the economic model of tax evasion, a tax reform should affect compliance through its impact on tax rates and incentives. Our findings demonstrate the importance of at least two further effects not covered by the traditional model: First, reform losers tend to evade more taxes after the reform. Second, a reform from a proportionate to a progressive system decreases compliance compared to a switch in the reverse direction. However, the level of compliance is generally higher under a progressive than under a proportionate regime.tax reforms; tax compliance; experiment

Tax compliance under tax regime changes

In this paper we focus on the compliance effects of tax regime changes. According to the economic model of tax evasion, a tax reform should affect compliance through its impact on tax rates and incentives. Our findings demonstrate the importance of at least two further effects not covered by the traditional model: First, reform losers tend to evade more taxes after the reform. Second, a reform from a proportionate to a progressive system decreases compliance compared to a switch in the reverse direction. However, the level of compliance is generally higher under a progressive than under a proportionate regime. --tax reforms,tax compliance,experiment

Religion and the shadow economy

Religion is increasingly acknowledged to be a cultural dimension which affects economic outcomes in different regards. This contribution focuses on religion's possible impact on the shadow economy. Different dimensions of the religious markets are taken into account. These dimensions refer to the overall degree of religiosity, the specific impact of different religions, religious competition or the proximity between religion and the state. The empirical test makes use of the largest available cross-section on the size of the shadow economy and matches this dataset with numerous religious indicators. Summary measures of general religiosity or indicators of religious competition do not have a measurable impact. However, robust differences emerge across religions. Countries dominated by Islam or Eastern religions are associated with smaller shadow economies compared to Christian countries. Furthermore, the proximity between state and religion matters. Close ties between both are typical for smaller shadow economies. This is in line with the view that religion uses its normative influence to protect state interests if there is a mutually beneficial relationship

Linear coupling of modes in 2D radially stratified astrophysical discs

We investigate mode coupling in a two dimensional compressible disc with radial stratification and differential rotation. We employ the global radial scaling of linear perturbations and study the linear modes in the local shearing sheet approximation. We employ a three-mode formalism and study the vorticity (W), entropy (S) and compressional (P) modes and their coupling properties. The system exhibits asymmetric three-mode coupling: these include mutual coupling of S and P-modes, S and W-modes, and asymmetric coupling between the W and P-modes. P-mode perturbations are able to generate potential vorticity through indirect three-mode coupling. This process indicates that compressional perturbations can lead to the development of vortical structures and influence the dynamics of radially stratified hydrodynamic accretion and protoplanetary discs.Comment: 10 pages, 10 figures, MNRAS (accepted

Long-term coastal-polynya dynamics in the southern Weddell Sea from MODIS thermal-infrared imagery

Based upon thermal-infrared satellite imagery in combination with ERA-Interim atmospheric reanalysis data, we derive long-term polynya characteristics such as polynya area, thin-ice thickness distribution, and ice-production rates for a 13-year investigation period (2002–2014) for the austral winter (1 April to 30 September) in the Antarctic southern Weddell Sea. All polynya parameters are derived from daily cloud-cover corrected thin-ice thickness composites. The focus lies on coastal polynyas which are important hot spots for new-ice formation, bottom-water formation, and heat/moisture release into the atmosphere. MODIS has the capability to resolve even very narrow coastal polynyas. Its major disadvantage is the sensor limitation due to cloud cover. We make use of a newly developed and adapted spatial feature reconstruction scheme to account for cloud-covered areas. We find the sea-ice areas in front of the Ronne and Brunt ice shelves to be the most active with an annual average polynya area of 3018 ± 1298 and 3516 ± 1420 km2 as well as an accumulated volume ice production of 31 ± 13 and 31 ± 12 km3, respectively. For the remaining four regions, estimates amount to 421 ± 294 km2 and 4 ± 3 km3 (Antarctic Peninsula), 1148 ± 432 km2 and 12 ± 5 km3 (iceberg A23A), 901 ± 703 km2 and 10 ± 8 km3 (Filchner Ice Shelf), as well as 499 ± 277 km2 and 5 ± 2 km3 (Coats Land). Our findings are discussed in comparison to recent studies based on coupled sea-ice/ocean models and passive-microwave satellite imagery, each investigating different parts of the southern Weddell Sea