Beauty in the Classroom: Professors' Pulchritude and Putative Pedagogical Productivity

Adjusted for many other determinants, beauty affects earnings; but does it lead directly to the differences in productivity that we believe generate earnings differences? We take a large sample of student instructional ratings for a group of university professors, acquire six independent measures of their beauty and a number of other descriptors of them and their classes. Instructors who are viewed as better looking receive higher instructional ratings, with the impact of a move from the 10th to the 90th percentile of beauty being substantial. This impact exists within university departments and even within particular courses, and is larger for male than for female instructors. Disentangling whether this outcome represents productivity or discrimination is, as with the issue generally, probably impossible.

Cosmic ray experiments /elementary particle physics/ in a manned orbiting laboratory

High energy cosmic ray experiments in manned orbiting laborator

Classification of Dimension 5 Lorentz Violating Interactions in the Standard Model

We give a complete classification of mass dimension five Lorentz-non-invariant interactions composed from the Standard Model fields, using the effective field theory approach. We identify different classes of Lorentz violating operators, some of which are protected against transmutation to lower dimensions even at the loop level. Within each class of operators we determine a typical experimental sensitivity to the size of Lorentz violation.Comment: 26 page

Food Stamps as Money and Income

Food Stamps represent nearly $11 billion of personal income in the United States. The coupons that are issued to represent the purchasing power available to recipients are also reserves for the commercial banking system.This study asks how closely these coupons are substitutable for what is usually considered as money, and how well Food Stamps function as a fiscal stabilizer (whether they increase consumption more than does ordinary income). The results, based on estimates for 1959-1981, suggest that Food Stamp coupons are perfectly substitutable for Ml, and a revised money-supply series including "Food Stamp Money" is included in an Appendix. Estimates of consumption functions indicate that the MPC out of income in the form of Food Stamps is higher than that out of ordinary income. Taken together, the results suggest that the Food Stamp program is an automatic fiscal and monetary stabilizer -- under its provisions, both the money stock and disposable income are increased during a recession.

Spin-Current-Induced Charge Accumulation and Electric Current in Semiconductor Nanostructures with Rashba Spin-Orbit Coupling

We demonstrate that the flow of a longitudinal spin current with different spin polarization will induce different patterns of charge accumulation in a two-terminal strip, or electric current distribution in a four-terminal Hall-bar structure, of two-dimensional electron gas with Rashba spin-orbit coupling (RSOC). For an in-plane polarized spin current, charges will accumulate either by the two lateral edges or around the center of the strip structure while, for an out-of-plain polarized spin current, charge densities will show opposite signs by the two lateral edges leading to a Hall voltage. Our calculation offers a new route to experimentally detect or differentiate pure spin currents with various spin polarization.Comment: 4 pages, 3 figure

Tools or Toys? The Impact of High Technology on Scholarly Productivity

Toys. The impact of computers on productivity has been examined directly on macro data and indirectly (on wages) using microeconomic data. This study examines the direct impact on the productivity of scholarship by considering how high technology might alter patterns of coauthoring of articles in economics and their influence. Using all coauthored articles in three major economics journals from 1970-79 and 1992-96, we find: 1) Sharp growth in the percentage of distant coauthorships (those between authors who were not in the same metropolitan areas in the four years prior to publication), as the theory predicts. Contrary to the theory: 2) Lower productivity (in terms of subsequent citations) of distant than close-coauthored papers; and 3) No decline in their relative disadvantage between the 1970s and 1990s. These findings are reconciled by the argument that high-technology functions as a consumption rather than an investment good. As such, it can be welfare-increasing without increasing productivity.

Exotic spin, charge and pairing correlations of the two-dimensional doped Hubbard model: a symmetry entangled mean-field approach

Intertwining of spin, charge and pairing correlations in the repulsive two-dimensional Hubbard model is shown through unrestricted variational calculations, with projected wavefunctions free of symmetry breaking. A crossover from incommensurate antiferromagnetism to stripe order naturally emerges in the hole-doped region when increasing the on-site coupling. Although effective pairing interactions are identified, they are strongly fragmented in several modes including d-wave pairing and more exotic channels related to an underlying stripe. We demonstrate that the entanglement of a mean-field wavefunction by symmetry restoration can largely account for interaction effects.Comment: Minor corrections, one reference adde

Symmetries and collective excitations in large superconducting circuits

The intriguing appeal of circuits lies in their modularity and ease of fabrication. Based on a toolbox of simple building blocks, circuits present a powerful framework for achieving new functionality by combining circuit elements into larger networks. It is an open question to what degree modularity also holds for quantum circuits -- circuits made of superconducting material, in which electric voltages and currents are governed by the laws of quantum physics. If realizable, quantum coherence in larger circuit networks has great potential for advances in quantum information processing including topological protection from decoherence. Here, we present theory suitable for quantitative modeling of such large circuits and discuss its application to the fluxonium device. Our approach makes use of approximate symmetries exhibited by the circuit, and enables us to obtain new predictions for the energy spectrum of the fluxonium device which can be tested with current experimental technology

Charge centers in CaF2_2: Ab initio calculation of elementary physical properties

Charge centers in ionic crystals provide a channel for elementary interaction between electromagnetic radiation and the lattice. We calculate the electronic ground state energies which are needed to create a charge center -- namely a $F$- and a $H$-center. In well agreement with common understanding the $F$-center results in being accompanied by a small lattice distortion whereas the $H$-center is accompanied by a very large lattice deformation. Opposite to the common understanding the additional positive charge in the charge center results rather to be localized on a F$_4^{3-}$ complex than on a F$_2^-$-complex. From the ground states of the charge centers we derive binding energies, diffusion barriers and agglomeration energies for $M$-center formation. These microscopic quantities are of fundamental interest to understand the dynamic processes which are initiated if the crystals interact with extreme intense deep ultra violet radiation. We further derive the equilibrium concentrations of charge centers in grown crystals.Comment: to appear in Phys. Rev. B in Aug. 2006, 11 Fig

On the Use of Group Theoretical and Graphical Techniques toward the Solution of the General N-body Problem

Group theoretic and graphical techniques are used to derive the N-body wave function for a system of identical bosons with general interactions through first-order in a perturbation approach. This method is based on the maximal symmetry present at lowest order in a perturbation series in inverse spatial dimensions. The symmetric structure at lowest order has a point group isomorphic with the S_N group, the symmetric group of N particles, and the resulting perturbation expansion of the Hamiltonian is order-by-order invariant under the permutations of the S_N group. This invariance under S_N imposes severe symmetry requirements on the tensor blocks needed at each order in the perturbation series. We show here that these blocks can be decomposed into a basis of binary tensors invariant under S_N. This basis is small (25 terms at first order in the wave function), independent of N, and is derived using graphical techniques. This checks the N^6 scaling of these terms at first order by effectively separating the N scaling problem away from the rest of the physics. The transformation of each binary tensor to the final normal coordinate basis requires the derivation of Clebsch-Gordon coefficients of S_N for arbitrary N. This has been accomplished using the group theory of the symmetric group. This achievement results in an analytic solution for the wave function, exact through first order, that scales as N^0, effectively circumventing intensive numerical work. This solution can be systematically improved with further analytic work by going to yet higher orders in the perturbation series.Comment: This paper was submitted to the Journal of Mathematical physics, and is under revie