How Progressive is the U.S. Federal Tax System? A Historical and International Perspective

This paper provides estimates of federal tax rates by income groups in the United States since 1960, with special emphasis on very top income groups. We include individual and corporate income taxes, payroll taxes, and estate and gift taxes. The progressivity of the U.S. federal tax system at the top of the income distribution has declined dramatically since the 1960s. This dramatic drop in progressivity is due primarily to a drop in corporate taxes and in estate and gift taxes combined with a sharp change in the composition of top incomes away from capital income and toward labor income. The sharp drop in statutory top marginal individual income tax rates has contributed only moderately to the decline in tax progressivity. International comparisons confirm that is it critical to take into account other taxes than the individual income tax to properly assess the extent of overall tax progressivity, both for time trends and for cross-country comparisons. The pattern for the United Kingdom is similar to the US pattern. France had less progressive taxes than the US or UK in 1970 but has experienced an increase in tax progressivity and has now a more progressive tax system than the US or the UK.

The Evolution of Top Incomes: A Historical and International Perspective

This paper summarizes the main findings of the recent studies that have constructed top income and wealth shares series over the century for a number of countries using tax statistics. Most countries experience a dramatic drop in top income shares in the first part of the century due to a precipitous drop in large wealth holdings during the wars and depression shocks. Top income shares do not recover in the immediate post war decades. However, over the last 30 years, top income shares have increased substantially in English speaking countries but not at all in continental Europe countries or Japan. This increase is due to an unprecedented surge in top wage incomes starting in the 1970s and accelerating in the 1990s. As a result, top wage earners have replaced capital income earners at the top of the income distribution in English speaking countries. We discuss the proposed explanations and the main questions that remain open.

Low-Thrust Lyapunov to Lyapunov and Halo to Halo with L2L^2-Minimization

In this work, we develop a new method to design energy minimum low-thrust missions (L2-minimization). In the Circular Restricted Three Body Problem, the knowledge of invariant manifolds helps us initialize an indirect method solving a transfer mission between periodic Lyapunov orbits. Indeed, using the PMP, the optimal control problem is solved using Newton-like algorithms finding the zero of a shooting function. To compute a Lyapunov to Lyapunov mission, we first compute an admissible trajectory using a heteroclinic orbit between the two periodic orbits. It is then used to initialize a multiple shooting method in order to release the constraint. We finally optimize the terminal points on the periodic orbits. Moreover, we use continuation methods on position and on thrust, in order to gain robustness. A more general Halo to Halo mission, with different energies, is computed in the last section without heteroclinic orbits but using invariant manifolds to initialize shooting methods with a similar approach

Income Inequality in the United States, 1913-1998 (series updated to 2000 available)

This paper presents new homogeneous series on top shares of income and wages from 1913 to 1998 in the US using individual tax returns data. Top income and wages shares display a U-shaped pattern over the century. Our series suggest that the 'technical change' view of inequality dynamics cannot fully account for the observed facts. The large shocks that capital owners experienced during the Great Depression and World War II seem to have had a permanent effect: top capital incomes are still lower in the late 1990s than before World War I. A plausible explanation is that steep progressive taxation, by reducing drastically the rate of wealth accumulation at the top of the distribution, has prevented large fortunes to recover fully yet from these shocks. The evidence on wage inequality shows that top wage shares were flat before WWII and dropped precipitously during the war. Top wage shares have started recovering from this shock since the 1960s-1970s and are now higher than before WWII. We emphasize the role of social norms as a potential explanation for the pattern of wage shares. All the tables and figures have been updated to the year 2000, the are available in excel format in the data appendix of the paper.

Temperature dependence of Raman scattering in filled double-walled carbon nanotubes

Four types of filled double-walled carbon nanotubes (DWNTs) (Se@DWNT; Te@DWNT; HgTe@DWNT; and PbI2@DWNT) have been studied by high-resolution transmission electron microscopy and micro-Raman spectroscopy in the temperature interval from 80 to 700 K employing 785 nm excitation wavelength. The temperature dependence of the dominant bands (D-band, G-band, and the (2D)-band) are analyzed in terms of the model developed by Klemens, Hart, Agraval, Lax, and Cowley and extended by Balkanski for anharmonic decay of optical phonons. The quasiharmonic frequencies and the anharmonicity constants were obtained from the temperature dependences of the analyzed Raman bands. The findings were compared to analogous study for empty DWNTs. The strength of the van der Waals interaction between the guest material and the carbon nanotube (CNT) estimated through the quasiharmonic frequencies was found to decrease in the following order: Se@DWNT; Te@DWNT; PbI2@DWNT, and HgTe@DWNT. In agreement with this, the anharmonicity due to the phonon–phonon interactions was found to decrease in the same order

QR Factorization of Tall and Skinny Matrices in a Grid Computing Environment

Previous studies have reported that common dense linear algebra operations do not achieve speed up by using multiple geographical sites of a computational grid. Because such operations are the building blocks of most scientific applications, conventional supercomputers are still strongly predominant in high-performance computing and the use of grids for speeding up large-scale scientific problems is limited to applications exhibiting parallelism at a higher level. We have identified two performance bottlenecks in the distributed memory algorithms implemented in ScaLAPACK, a state-of-the-art dense linear algebra library. First, because ScaLAPACK assumes a homogeneous communication network, the implementations of ScaLAPACK algorithms lack locality in their communication pattern. Second, the number of messages sent in the ScaLAPACK algorithms is significantly greater than other algorithms that trade flops for communication. In this paper, we present a new approach for computing a QR factorization -- one of the main dense linear algebra kernels -- of tall and skinny matrices in a grid computing environment that overcomes these two bottlenecks. Our contribution is to articulate a recently proposed algorithm (Communication Avoiding QR) with a topology-aware middleware (QCG-OMPI) in order to confine intensive communications (ScaLAPACK calls) within the different geographical sites. An experimental study conducted on the Grid'5000 platform shows that the resulting performance increases linearly with the number of geographical sites on large-scale problems (and is in particular consistently higher than ScaLAPACK's).Comment: Accepted at IPDPS10. (IEEE International Parallel & Distributed Processing Symposium 2010 in Atlanta, GA, USA.

PhaseLift: Exact and Stable Signal Recovery from Magnitude Measurements via Convex Programming

Suppose we wish to recover a signal x in C^n from m intensity measurements of the form ||^2, i = 1, 2,..., m; that is, from data in which phase information is missing. We prove that if the vectors z_i are sampled independently and uniformly at random on the unit sphere, then the signal x can be recovered exactly (up to a global phase factor) by solving a convenient semidefinite program---a trace-norm minimization problem; this holds with large probability provided that m is on the order of n log n, and without any assumption about the signal whatsoever. This novel result demonstrates that in some instances, the combinatorial phase retrieval problem can be solved by convex programming techniques. Finally, we also prove that our methodology is robust vis a vis additive noise