Symmetry Aspects and Finite-Size Scaling of Quantum Hall Fluids

The exactness and universality observed in the quantum Hall effect suggests the existence of a symmetry principle underlying Laughlin's theory. We review the role played by the infinite $W_{\infty }$ and conformal algebras as dynamical symmetries of incompressible quantum fluids and show how they predict universal finite-size effects in the excitation spectrum.Comment: 15 pages, CERN-TH-6784/93, LateX fil

Management Jobs in the Insurance Industry: Organizational Deskilling and Rising Pay Inequality

The attention of both the research community and the popular press has begun to shift from a traditional focus on production jobs and toward management positions in part because of a perception that a fundamental change is underway in the management ranks. Unlike the temporary layoffs of production workers that were historically driven by business cycles, the changes in management job security seem to be permanent and, in large measure, driven by development inside the firm. The most important of these forces appear to be changes in the structure of management and in the organization of work processes. The authors use a unique set of data to examine the structure of management jobs among a sample of companies and observe how those jobs have changed over time. They examine changes in the skill requirements of jobs by functional area and by level in the organization, changes in the "shape" of the organization chart - the distribution of employees across management job titles - and changes in compensation for these jobs. The data were obtained from Hay Associates, and it included the internal organization of management jobs for 11 life insurance companies. The authors see a sharp expansion in the proportion of line workers, absolute declines in the number of top management positions, and only modest growth in the number of middle managers and supervisors. As a result the organization chart has changed dramatically in these companies, becoming considerably flatter. The "span of control" has increased for every level of the organization and especially for first level management. If the widening of the supervisory span of control resulted from taking decision making and responsibility from supervisors and pushing it down to line workers, it does not seem to have increased the average skill requirements of the exempt line workers. Skill requirements for the other levels rose over the period, especially for top management positions. Overall, the average level of skill in the sample fell substantially between 1986 and 1992 (even though skills rose in two of the four levels) because of a sharp shift in the distribution of employment away from management and toward line positions. The authors suggest that the best description of these patterns is that they represent upskilling of individual jobs and deskilling of organizations. Regarding compensation, none of the levels experienced increases in skill that were statically significant, but top managers received a large (28 percent) increase in pay, middle managers received a modest (10 percent) increase, and the lower two levels received virtually no increases. One conclusion is that earnings inequality is increasing substantially inside these firms in a manner that is not attributable to any increase in skill, and the dividing line for that growth in inequality is no longer exempt/nonexempt but supervisor/manager. A possible explanation for the rising inequality in compensation is that it helps offset change in the probability of promotion. The fact that the span of control is increasing and organizational chart flattening means that the probability of the average worker being promoted is declining. The decline in the probability of promotion might reduce the incentives to work hard. Increases in the compensation of top jobs increase the return to securing a promotion and may offset some of the effect produced by the decline in the probability of promotion. Another explanation is that top mangers are in "better positions to legislate their own pay increases." If true, this sample may actually underrepresent the true extent of income inequality because it consists of companies using an external consultant to help set compensation where internal consistency is an important characteristic of the pay system. These results suggest that "management" as a career will remain attractive, albeit less certain in terms of promotion prospects. Shifts to team-based approaches and the elimination of functional designations would suggest a greater need for generalists than specialists. As technology such as expert systems reduces the need for large units of "experts," the manger's skill will be in recognizing when an expert needs to be called. Leadership skills and the ability to adapt to a changing environment are two qualities that will be sought in the future. Fortunately, these skills will also be useful to team members who are not selected for promotion to mangers. Increasing income inequality may lead to distrust within the organization, though this may be offset by the technical tracks that allow highly skilled non-managers to earn equivalent levels of pay. The fact that insurance companies are relatively unique in facing no major industry-specific shocks from the outside environment suggests that these results should translate well to organizations in other industries.

Numerical Study of Hierarchical Hall Edge States on the Disk Geometry

We present a detailed analysis of the exact numerical spectrum of up to ten interacting electrons in the first Landau level on the disk geometry. We study the edge excitations of the hierarchical plateaus and check the predictions of two relevant conformal field theories: the multi-component Abelian theory and the W-infinity minimal theory of the incompressible fluids. We introduce two new criteria for identifying the edge excitations within the low-lying states: the plot of their density profiles and the study of their overlaps with the Jain wave functions in a meaningful basis. We find that the exact bulk and edge excitations are very well reproduced by the Jain states; these, in turn, can be described by the multi-component Abelian conformal theory. Most notably, we observe that the edge excitations form sub-families of the low-lying states with a definite pattern, which is explained by the W-infinity minimal conformal theory. Actually, the two conformal theories are related by a projection mechanism whose effects are observed in the spectrum. Therefore, the edge excitations of the hierarchical Hall states are consistently described by the W-infinity minimal theory, within the finite-size limitations.Comment: Revtex, 25 pages, 17 figures and 11 table

Oral liquid L-thyroxine (L-t4) may be better absorbed compared to L-T4 tablets following bariatric surgery.

Drug malabsorption is a potential concern after bariatric surgery. We present four case reports of hypothyroid patients who were well replaced with thyroxine tablets to euthyroid thyrotropin (TSH) levels prior to Roux-en-Y gastric bypass surgery. These patients developed elevated TSH levels after the surgery, the TSH responded reversibly to switching from treatment with oral tablets to a liquid formulation

Galois Modular Invariants of WZW Models

The set of modular invariants that can be obtained from Galois transformations is investigated systematically for WZW models. It is shown that a large subset of Galois modular invariants coincides with simple current invariants. For algebras of type B and D infinite series of previously unknown exceptional automorphism invariants are found.Comment: phyzzx macros, 38 pages. NIKHEF-H/94-3

The Haldane-Rezayi Quantum Hall State and Conformal Field Theory

We propose field theories for the bulk and edge of a quantum Hall state in the universality class of the Haldane-Rezayi wavefunction. The bulk theory is associated with the $c=-2$ conformal field theory. The topological properties of the state, such as the quasiparticle braiding statistics and ground state degeneracy on a torus, may be deduced from this conformal field theory. The 10-fold degeneracy on a torus is explained by the existence of a logarithmic operator in the $c=-2$ theory; this operator corresponds to a novel bulk excitation in the quantum Hall state. We argue that the edge theory is the $c=1$ chiral Dirac fermion, which is related in a simple way to the $c=-2$ theory of the bulk. This theory is reformulated as a truncated version of a doublet of Dirac fermions in which the $SU(2)$ symmetry -- which corresponds to the spin-rotational symmetry of the quantum Hall system -- is manifest and non-local. We make predictions for the current-voltage characteristics for transport through point contacts.Comment: 37 pages, LaTeX. Some references added, minor changes at the end of section