Efficient Labor Force Participation with Search and Bargaining

A fixed wage is inefficient in a standard search model when workers endogenously separate from employment. We derive an efficient employment contract that involves agents paying a hiring fee (or bond) upon the formation of a match. We estimate the fixed wage and efficient contract assuming the hiring fee is unobservable, and find evidence to reject the efficient contract in favor of the fixed wage rule. A counterfactual experiment reveals the current level of labor force participation to be 9% below the efficient level, and a structural shift to the efficient contract improves welfare by nearly 4%.labor supply, unemployment, matching, efficiency wages

Energy Density of Vortices in the Schroedinger Picture

The one-loop energy density of an infinitely thin static magnetic vortex in SU(2) Yang-Mills theory is evaluated using the Schroedinger picture. Both the gluonic fluctuations as well as the quarks in the vortex background are included. The energy density of the magnetic vortex is discussed as a function of the magnetic flux. The center vortices correspond to local minima in the effective potential. These minima are degenerated with the perturbative vacuum if the fermions are ignored. Inclusion of fermions lifts this degeneracy, raising the vortex energy above the energy of the perturbative vacuum.Comment: 25 pages, 2 figure

Writhe of center vortices and topological charge -- an explicit example

The manner in which continuum center vortices generate topological charge density is elucidated using an explicit example. The example vortex world-surface contains one lone self-intersection point, which contributes a quantum 1/2 to the topological charge. On the other hand, the surface in question is orientable and thus must carry global topological charge zero due to general arguments. Therefore, there must be another contribution, coming from vortex writhe. The latter is known for the lattice analogue of the example vortex considered, where it is quite intuitive. For the vortex in the continuum, including the limit of an infinitely thin vortex, a careful analysis is performed and it is shown how the contribution to the topological charge induced by writhe is distributed over the vortex surface.Comment: 33 latex pages, 10 figures incorporating 14 ps files. Furthermore, the time evolution of the vortex line discussed in this work can be viewed as a gif movie, available for download by following the PostScript link below -- watch for the cute feature at the self-intersection poin

Isolated familial pheochromocytoma as a variant of von Hippel-Lindau disease.

Inherited pheochromocytomas are often part of familial syndromes, especially multiple endocrine neoplasia type 2 (MEN 2), retinal cerebellar hemangioblastomatosis [von Hippel-Lindau (vHL) disease] or neurofibromatosis type 1. It is not clear whether isolated familial pheochromocytoma exists as a separate clinical entity. In a family with pheochromocytomas in three generations and with at least seven affected members, we investigated by clinical and genetic analyses the presence or absence of associated conditions. The clinical investigations included ophthalmological and radiological studies for von Hippel-Lindau disease (magnetic resonance imaging of the brain, computed tomography of the abdomen, and direct ophthalmoscopy after mydriasis) and annual calcitonin stimulation tests for C cell disease in five members who agreed to regular follow-up. Besides the pheochromocytomas (so far, these have been multiple in five of seven individuals) no definite second associated condition was found. Genetic analysis did not identify any MEN 2-specific RET protooncogene point mutations (which are present in 97% of MEN 2a families). However, despite the complete absence of other clinical manifestations of the vHL disease (besides pheochromocytomas), a previously undescribed germline missense mutation in the vHL tumor suppressor gene was found (C775G transversion with a predicted substitution of a leucine by a valine at codon 259 in the putative vHL protein). We conclude that in this family the sole occurrence of pheochromocytoma is a variant of vHL disease

Vortex critical behavior at the de-confinement phase transition

The de-confinement phase transition in SU(2) Yang-Mills theory is revisited in the vortex picture. Defining the world sheets of the confining vortices by maximal center projection, the percolation properties of the vortex lines in the hypercube consisting of the time axis and two spatial axis are studied. Using the percolation cumulant, the temperature for the percolation transition is seen to be in good agreement with the critical temperature of the thermal transition. The finite size scaling function for the cumulant is obtained. The critical index of the finite size scaling function is consistent with the index of the 3D Ising model.Comment: 4 pages, 4 PS figures, using revtex4, paragraph and refs added, typo correcte

Nomenclature of structural and compositional characteristics of ordered microporous and mesoporous materials with inorganic hosts(IUPAC Recommendations 2001)

A system of terms applicable to ordered microporous and mesoporous materials is proposed, and rules for writing a standardized crystal chemical formula for such materials are presented. The recommendations are based both on common usage and on a systematic classification scheme. The nomenclature has been developed to encompass all inorganic materials with ordered, accessible pores with free diameters of less than 50 nm. The crystal chemical formula describes the chemical composition of both the guest species and the host, the structure of the host, the structure of the pore system, and the symmetry of the material. This formula can be simplified or expanded to suit the user's requirement

Monopoly Power with a Short Selling Constraint

We show if a speculator can benefit from reducing a monopoly’s rents through short selling, then a speculator may take a short position in a monopoly, overcome the barriers to entry, and compete with the monopoly. The competition drives down the monopoly’s rents, and as a result, the short position becomes profitable and covers the cost of entry. If entry is impossible, then the speculator may coordinate and pay the firm’s counter-parties to stop trading with the monopoly rather than entering. Either way, increasing a speculator’s ability to short a firm’s rents results in a constraint on the monopoly and forces it to act more like a price taker. The mechanism is a market based approach to antitrust

Topological Susceptibility of Yang-Mills Center Projection Vortices

The topological susceptibility induced by center projection vortices extracted from SU(2) lattice Yang-Mills configurations via the maximal center gauge is measured. Two different smoothing procedures, designed to eliminate spurious ultraviolet fluctuations of these vortices before evaluating the topological charge, are explored. They result in consistent estimates of the topological susceptibility carried by the physical thick vortices characterizing the Yang-Mills vacuum in the vortex picture. This susceptibility is comparable to the one obtained from the full lattice Yang-Mills configurations. The topological properties of the SU(2) Yang-Mills vacuum can thus be accounted for in terms of its vortex content.Comment: 12 revtex pages, 6 ps figures included using eps