Distributional Changes in the Gender Wage Gap

This paper analyzes changes in wage differentials between white men and white women over the period 1993–2006 across the entire wage distribution using Panel Study of Income Dynamics (PSID) data. We decompose distributional changes in the gender wage gap to assess the contribution of observed characteristics measuring individual productivity. We fi nd that the gender wage gap narrowed by more than 13 percent at the lowest decile and by less than 4 percent at the highest decile. The decomposition results indicate that changes in the gender wage gap are mainly attributable to changes in educational attainment at the top of the wage distribution, while a sizeable part of the changes is due to work history changes at the bottom. Our findings suggest that the educational success of women could reduce the gender wage gap at the bottom of the distribution both before and during the 1990s but did not trigger a strong decline at the top of the distribution until today.Gender wage gap; decomposition analysis; unconditional quantile regression

Electron-magnon scattering in elementary ferromagnets from first principles: lifetime broadening and band anomalies

We study the electron-magnon scattering in bulk Fe, Co, and Ni within the framework of many-body perturbation theory implemented in the full-potential linearized augmented-plane-wave method. To this end, a $\mathbf{k}$-dependent self-energy ($GT$ self-energy) describing the scattering of electrons and magnons is constructed from the solution of a Bethe-Salpeter equation for the two-particle (electron-hole) Green function, in which single-particle Stoner and collective spin-wave excitations (magnons) are treated on the same footing. Partial self-consistency is achieved by the alignment of the chemical potentials. The resulting renormalized electronic band structures exhibit strong spin-dependent lifetime effects close to the Fermi energy, which are strongest in Fe. The renormalization can give rise to a loss of quasiparticle character close to the Fermi energy, which we attribute to electron scattering with spatially extended spin waves. This scattering is also responsible for dispersion anomalies in conduction bands of iron and for the formation of satellite bands in nickel. Furthermore, we find a band anomaly at a binding energy of 1.5~eV in iron, which results from a coupling of the quasihole with single-particle excitations that form a peak in the Stoner continuum. This band anomaly was recently observed in photoemission experiments. On the theory side, we show that the contribution of the Goldstone mode to the $GT$ self-energy is expected to (nearly) vanish in the long-wavelength limit. We also present an in-depth discussion about the possible violation of causality when an incomplete subset of self-energy diagrams is chosen

External Memory Pipelining Made Easy With TPIE

When handling large datasets that exceed the capacity of the main memory, movement of data between main memory and external memory (disk), rather than actual (CPU) computation time, is often the bottleneck in the computation. Since data is moved between disk and main memory in large contiguous blocks, this has led to the development of a large number of I/O-efficient algorithms that minimize the number of such block movements. TPIE is one of two major libraries that have been developed to support I/O-efficient algorithm implementations. TPIE provides an interface where list stream processing and sorting can be implemented in a simple and modular way without having to worry about memory management or block movement. However, if care is not taken, such streaming-based implementations can lead to practically inefficient algorithms since lists of data items are typically written to (and read from) disk between components. In this paper we present a major extension of the TPIE library that includes a pipelining framework that allows for practically efficient streaming-based implementations while minimizing I/O-overhead between streaming components. The framework pipelines streaming components to avoid I/Os between components, that is, it processes several components simultaneously while passing output from one component directly to the input of the next component in main memory. TPIE automatically determines which components to pipeline and performs the required main memory management, and the extension also includes support for parallelization of internal memory computation and progress tracking across an entire application. The extended library has already been used to evaluate I/O-efficient algorithms in the research literature and is heavily used in I/O-efficient commercial terrain processing applications by the Danish startup SCALGO

Academic Freedom, Private-Sector Focus, and the Process of Innovation

We develop a model that clarifies the respective advantages and disadvantages of academic and private-sector research. Our model assumes full protection of intellectual property rights at all stages of the development process, and hence does not rely on lack of appropriability or spillovers to generate a rationale for academic research. Instead, we focus on control-rights considerations, and argue that the fundamental tradeoff between academia and the private sector is one of creative control versus focus. By serving as a precommitment mechanism that allows scientists to freely pursue their own interests, academia can be indispensable for early-stage research. At the same time, the private sector%u2019s ability to direct scientists towards higher-payoff activities makes it more attractive for later-stage research.

Retrieving time-dependent Green's functions in optics with low-coherence interferometry

We report on the passive measurement of time-dependent Green's functions in the optical frequency domain with low-coherence interferometry. Inspired by previous studies in acoustics and seismology, we show how the correlations of a broadband and incoherent wave-field can directly yield the Green's functions between scatterers of a complex medium. Both the ballistic and multiple scattering components of the Green's function are retrieved. This approach opens important perspectives for optical imaging and characterization in complex scattering media.Comment: 5 pages, 4 figure

Non-Perturbative Theory for Dispersion Self-Energy of Atoms

We go beyond the approximate series-expansions used in the dispersion theory of finite size atoms. We demonstrate that a correct, and non-perturbative, theory dramatically alters the dispersion selfenergies of atoms. The non-perturbed theory gives as much as 100% corrections compared to the traditional series expanded theory for the smaller noble gas atoms.Comment: 3 pages, no figures, 1 tabl

Verlaagde gewasverdamping : invloed van matwatergehalte en EC-gift op de verdamping bij tomaat

In een oriënterende proef is gepoogd de transpiratie van planten te sturen met verschillende behandelingen van de wortelomgeving. In een tomatengewas (Lycopersicum esculentum Mill.) op steenwol werden beperkte drainage (5%) en beperkte drainage met ochtendirrigatie met hogere EC vergeleken met een standaardbehandeling met 30% drainage. Omdat negatieve effecten van een hogere EC op vers gewicht en kwaliteit bekend zijn, werd geprobeerd de totale EC in de mat niet hoger te laten worden dan die van de standaardbehandeling. De transpiratie van planten is afhankelijk van de waterpotentiaal in de plant. Dit staat weer in verhouding tot het gemak waarmee de plant water kan opnemen uit het substraat. Daarom is de hypothese dat bij een tijdelijke verlaging van de osmotische potentiaal van de voedingsoplossing rond de wortels (dus een verhoging van de EC) de plant minder water zal gaan verdampen. Dit komt doordat de interne waterpotentiaal van de plant wordt aangepast. Sturing van de transpiratie van de plant via het wortelmilieu en niet door verandering in het kasklimaat is een nieuwe benaderin