A Historical Test of the Tiebout Hypothesis: Local Heterogeneity from 1850 to 1990

The Tiebout hypothesis, which states that individuals will costlessly sort themselves across local communities according to their public good preferences, is the workhorse of the local public finance literature. This paper develops a test of the Tiebout hypothesis using historical variation in mobility costs. Our extension of the Tiebout model to incorporate such costs yields the following comparative statics: as mobility costs fall, the heterogeneity across communities of individual public good preferences and, under some standard assumptions, of public good provision must (weakly) increase. Given mobility costs have fallen over time, a natural test of the Tiebout hypothesis is to take these predictions to the data here all US counties over the 1850-1990 period. Contrary to the predictions, we find decreasing heterogeneity between counties in policy outcomes (local education spending and total taxes or revenues) and in a wide variety of proxies for public good preferences (age groups, education levels, election outcomes, home ownership, income, race, and religious affiliation). Using the Boston SMSA as a case study, we show that the heterogeneity trends are similar at the municipal and county levels. These results suggest that forces working in opposition to Tiebout sorting have dominated individual location decisions over the past century.

Blood flow dynamics in patient specific arterial network in head and neck

This paper shows a steady simulation of blood flow in the major head and neck arteries as if they had rigid walls, using patient specific geometry and CFD software FLUENT R . The Artery geometry is obtained by CT–scan segmentation with the commercial software ScanIPTM. A cause and effect study with various Reynolds numbers, viscous models and blood fluid models is provided. Mesh independence is achieved through wall y+ and pressure gradient adaption. It was found, that a Newtonian fluid model is not appropriate for all geometry parts, therefore the non–Newtonian properties of blood are required for small vessel diameters and low Reynolds numbers. The k–! turbulence model is suitable for the whole Reynolds numbe

Simulation of haemodynamic flow in head and neck chemotherapy

In recent years, intra arterial chemotherapy has become an important component in head and neck cancer treatment. However, therapy success can vary significantly and consistent treatment guidelines are missing. The purpose of this study was to create a computer simulation of the chemical agent injection in the head and neck arteries to investigate the distribution and concentration of the chemical. This is of great interest for medical scientists and vital for prognosis. Realistic three dimensional patient specific geometry was created from image scan data. Engineering principles such as conservation of mass and momentum, turbulence models and a multiphase model were applied in a computational fluid dynamics (CFD) software. At first, a steady cause and effect study with various turbulence and material models was made without the chemical component. It was discovered, that a non-\Newtonian material model is compulsory for blood. The shear stress transport k-w turbulence model is appropriate for the whole velocity range and of superior robustness. These conclusions were used in the following two-component transient simulation. Pulsatile blood flow, turbulence, the chemical agent injection via a catheter and the mixture between blood and the chemical were considered. The principal conclusion was; the modelled catheter position right before the common carotid artery bifurcation produced an ineffective cisplatin distribution consistent throughout all the arteries. Due to high wall shear stress and turbulence at the inner bifurcation wall, serious complications during the treatment could occur, for instance heamolysis or acute vascular endothelial changes. To the best of the author\u27s knowledge a novel \CFD based approach was introduced, suitable for the optimization and the formulation of treatment guidelines in intra arterial injection chemotherapy. After a required validation, this model can be modified to investigate the influence of various catheter positions and dose rate schemes in future simulations

Holomorphic Parafermions in the Potts model and SLE

We analyse parafermionic operators in the Q-state Potts model from three different perspectives. First, we explicitly construct lattice holomorphic observables in the Fortuin-Kasteleyn representation, and point out some special simplifying features of the particular case Q=2 (Ising model). In particular, away from criticality, we find a lattice generalisation of the massive Majorana fermion equation. We also compare the parafermionic scaling dimensions with known results from CFT and Coulomb gas methods in the continuum. Finally, we show that expectation values of these parafermions correspond to local observables of the SLE process which is conjectured to describe the scaling limit of the Q-state Potts model.Comment: 18 pages. v2: references to related work clarified. v3: minor corrections, version accepted for publication in JSTA

Design improvement of a pump wear ring labyrinth seal

The investigation was successful in obtaining two improved designs for the impeller wear ring seal of the liquid hydrogen turbopump of interest. A finite difference computer code was extensively used in a parametric computational study in determining a cavity configuration with high flow resistance due to turbulence dissipation. These two designs, along with that currently used, were fabricated and tested. The improved designs were denoted Type O and Type S. The measurements showed that Type O and Type S given 67 and 30 percent reduction in leakage over the current design, respectively. It was found that the number of cavities, the step height and the presence of a small stator groove are quite important design features. Also, the tooth thickness is of some significance. Finally, the tooth height and an additional large cavity cut out from the stator (upstream of the step) are of negligible importance

The Globular Cluster System of the Spiral Galaxy NGC7814

We present the results of a wide-field photometric study of the globular cluster (GC) system of the edge-on Sab spiral NGC7814. This is the first spiral to be fully analyzed from our survey of the GC systems of a large sample of galaxies beyond the Local Group. NGC7814 is of particular interest because a previous study estimated that it has 500-1000 GCs, giving it the largest specific frequency (S_N) known for a spiral. Understanding this galaxy's GC system is important in terms of our understanding of the GC populations of spirals in general and has implications for the formation of massive galaxies. We observed the galaxy in BVR filters with the WIYN 3.5-m telescope, and used image classification and three-color photometry to select GC candidates. We also analyzed archival HST WFPC2 images of NGC7814, both to help quantify the contamination level of the WIYN GC candidate list and to detect GCs in the inner part of the galaxy halo. Combining HST data with high-quality ground-based images allows us to trace the entire radial extent of this galaxy's GC system and determine the total number of GCs directly through observation. We find that rather than being an especially high-S_N spiral, NGC7814 has <200 GCs and S_N ~ 1, making it comparable to the two most well-studied spirals, the Milky Way and M31. We explore the implications of these results for models of the formation of galaxies and their GC systems. The initial results from our survey suggest that the GC systems of typical ellipticals can be accounted for by the merger of two or more spirals, but that for highly-luminous ellipticals, additional physical processes may be needed.Comment: 28 pages, incl. 4 figures; accepted for publication in The Astronomical Journal, November 2003 issu

Evaluation of Skylab EREP data for land resource management

There are no author-identified significant results in this report

Form-finding and analysis of bending-active systems using dynamic relaxation

A common challenge for architects and engineers in the development of structurally efficient systems is the generation of good structural forms for a specific set of boundary conditions, a process known as form-finding. Dynamic relaxation is a wellestablished explicit numerical analysis method used for the form-finding and analysis of highly non-linear structures. With the incorporation of bending and clustered elements, the method can be extended for the analysis of complex curved and bending-active structural systems. Bending-active structures employ elastic deformation to generate complex curved shapes. With low computational cost, dynamic relaxation has large potential as a design and analysis technique of novel large span structural systems such as spline stressed membranes and small scale robotics, bio-mechanics and architectural applications made of novel materials such as electro- active polymers (EAP)

Band gap bowing in NixMg1-xO.

Epitaxial transparent oxide NixMg1-xO (0 ≤ x ≤ 1) thin films were grown on MgO(100) substrates by pulsed laser deposition. High-resolution synchrotron X-ray diffraction and high-resolution transmission electron microscopy analysis indicate that the thin films are compositionally and structurally homogeneous, forming a completely miscible solid solution. Nevertheless, the composition dependence of the NixMg1-xO optical band gap shows a strong non-parabolic bowing with a discontinuity at dilute NiO concentrations of x  0.074 and account for the anomalously large band gap narrowing in the NixMg1-xO solid solution system