Equalization and the Decentralization of Revenue-Raising in a Federation

We study federal economies in which regional governments have responsibility for delivering public services and redistributive objectives apply. The implications of these for the assignment of revenue-raising instruments and fiscal transfers, both vertical and horizontal, are considered. Models of heterogenous regions of varying degrees of complexity and generality are constructed. For each case, we determine what fiscal instruments must be given to the regions and what inter-governmental transfers must be made in order that the social optimum is achieved. With heterogenous households and regions, the social optimum can be decentralized by making regions responsible for redistribution and implementing equalization transfers that depend on the number of households of each type.

Giant proximity effect in a phase-fluctuating superconductor

When a tunneling barrier between two superconductors is formed by a normal material that would be a superconductor in the absence of phase fluctuations, the resulting Josephson effect can undergo an enormous enhancement. We establish this novel proximity effect by a general argument as well as a numerical simulation and argue that it may underlie recent experimental observations of the giant proximity effect between two cuprate superconductors separated by a barrier made of the same material rendered normal by severe underdoping.Comment: 4 pages, 3 figures; version to appear in PRL (results of simulations in 3d added). For related work and info visit http://www.physics.ubc.ca/~fran

Contact angles on a soft solid: from Young's law to Neumann's law

The contact angle that a liquid drop makes on a soft substrate does not obey the classical Young's relation, since the solid is deformed elastically by the action of the capillary forces. The finite elasticity of the solid also renders the contact angles different from that predicted by Neumann's law, which applies when the drop is floating on another liquid. Here we derive an elasto-capillary model for contact angles on a soft solid, by coupling a mean-field model for the molecular interactions to elasticity. We demonstrate that the limit of vanishing elastic modulus yields Neumann's law or a slight variation thereof, depending on the force transmission in the solid surface layer. The change in contact angle from the rigid limit (Young) to the soft limit (Neumann) appears when the length scale defined by the ratio of surface tension to elastic modulus $\gamma/E$ reaches a few molecular sizes

Formations Near the Libration Points: Design Strategies Using Natural and Non-Natural Arcs

Space based observatory and interferometry missions, such as Terrestrial Planet Finder (TPF), Stellar Imager, and MAXIM, have sparked great interest in multi-spacecraft formation flight in the vicinity of the Sun-Earth/Moon (SEM) libration points. The initial phase of this research considered the formation keeping problem from the perspective of continuous control as applied to non-natural formations. In the present study, closer inspection of the flow, corresponding to the stable and center manifolds near the reference orbit, reveals some interesting natural relative motions as well as some discrete control strategies for deployment. A hybrid control strategy is also employed that combines both the natural formation dynamics with non-natural motions via input feedback linearization techniques

An Autonomous Onboard Targeting Algorithm Using Finite Thrust Maneuvers

In earlier investigations, the adaptation and implementation of a modified two-level corrections process as the onboard targeting algorithm for the Trans-Earth Injection phase of Orion is presented. The objective of that targeting algorithm is to generate the times of ignition and magnitudes of the required maneuvers such that the desired state at entry interface is achieved. In an actual onboard flight software implementation, these times of ignition and maneuvers are relayed onto Flight Control for command and execution. Although this process works well when the burn durations or burn arcs are small, this might not be the case during a contingency situation when lower thrust engines are employed to perform the maneuvers. Therefore, a new version of the modified two-level corrections process is formulated to handle the case of finite burn arcs. This paper presents the development and formulation of that finite burn modified two-level corrections process which can again be used as an onboard targeting algorithm for the Trans-Earth Injection phase of Orion. Additionally, performance results and a comparison between the two methods are presented. The finite burn two-level corrector formulation presented here ensures the entry constraints at entry interface are still met without violating the available fuel budget, while still accounting for much longer burn times in its design

Subsolidus Phase Relationships in Si 3 N 4 –AlN–Rare-Earth Oxide Systems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65239/1/j.1151-2916.1986.tb07349.x.pd

Evaluating the pronunciation component of text-to-speech systems for English: A performance comparison of different approaches

The automatic derivation of word pronunciations from input text is a central task for any text-to-speech system. For general English text at least, this is often thought to be a solved problem, with manually-derived linguistic rules assumed capable of handling `novel' words missing from the system dictionary. Data-driven methods, based on machine learning of the regularities implicit in a large pronouncing dictionary, have received considerable attention recently but are generally thought to perform less well. However, these tentative beliefs are at best uncertain without powerful methods for comparing text-to-phoneme subsystems. This paper contributes to the development of such methods by comparing the performance of four representative approaches to automatic phonemisation on the same test dictionary. As well as rule-based approaches, three data-driven techniques are evaluated: pronunciation by analogy (PbA), NETspeak and IB1-IG (a modified k-nearest neighbour method). Issues involved in comparative evaluation are detailed and elucidated. The data-driven techniques outperform rules in accuracy of letter-to-phoneme translation by a very significant margin but require aligned text-phoneme training data and are slower. Best translation results are obtained with PbA at approximately 72% words correct on a reasonably large pronouncing dictionary, compared to something like 26% words correct for the rules, indicating that automatic pronunciation of text is not a solved problem

The production and collecting of plaster and sulpher paste "impronte" as Grand Tour souvenirs in the 18th and 19th centuries

Whilst investigating the origins and nature of impronte, it became increasingly obvious that as objects in and of themselves, very little comprehensive work had been done to address questions of where, how, and why these objects came to be made. Initial inquiries to various museums and individuals demonstrated that these were not particularly rare items, they were abundant, and commonplace but little understood as objects of art. Typically, impronte are considered to be representations of gemstones, this work is intended to demonstrate that there is a broader dimension to the subjects depicted by impronte. Chapter one contains a brief overview of the historical context of gem collecting and the traditional processes of working on hardstones. The 18th century revival of interest in classical knowledge was directly responsible for the resurgence in the interest in amassing collections of ancient gemstones; as well as the collection of modern gemstones carved in the manner of the ancients. This revival, while stimulating renewed interest in gemstones, was so lucrative that it also encouraged numerous forgeries to be made. The quantity and quality of forgeries was to ultimately undermine confidence in the authenticity of gemstones and result in a collapse of the popular market for the collecting of gemstones, and by extension, impronte. Chapter two is an examination of the practical issues relating to the materials, manufacture, and conservation of impronte. The materials commonly encountered are sulpher and plaster, on rare occasion, glass paste. A large portion of the chapter is devoted to the different aspects of manufacturing impronte. Other sections are concerned with the problems relating to the conservation, storage and cleaning of impronte in the museum environment. Chapter three is an overview of the biographical details and commercial activities of the known makers of impronte represented in private and public collections in the UK and elsewhere. Chapter four is a discussion of the variety of themes and subjects portrayed on impronte. There is a wide diversity of subject material contained in sets of impronte, and not all are strictly pertinent to the traditional subjects treated by gemstones. Large numbers of impronte are intended to be visual study aids, and souvenirs, of great works of art, both ancient and modern held in various famous collections popular with 'Grand tourists'. In many instances impronte are more similar to an 18th and 19th century version of a postcard, or slide package, purchased by modern museum visitors and art lovers. The four appendices contain information about the collection of impronte at the Ashmolean Museum, Oxford; details from 19th century guidebooks to the artisans of Rome, written by Heinrich Keller; a catalogue of the collection of Paoletti impronte at the University of St Andrews; and sample details of the conservation survey of the Ashmolean collection

Investigation of Alternative Return Strategies for Orion Trans-earth Injection Design Options

The purpose of this study is to investigate alternative return strategies for the Orion trans-Earth injection (TEI) phase. A dynamical systems analysis approach considers the structure of the stable and unstable Sun perturbed Earth-Moon manifolds near the Earth-Moon interface region. A hybrid approach, then, combines the results from this analysis with classical two-body methods in a targeting process that seeks to expand the window of return opportunities in a precision entry scenario. The resulting startup arcs can be used, for instance, to enhance the block set of solutions available onboard during an autonomous targeting process

Intracerebral Implantation of Hydrogel-Coupled Adhesion Peptides: Tissue Reaction

Arg-Gly-Asp peptides (RGD) were synthesized and chemically coupled to the bulk of N-(2-hydroxypropyl) methacrylamide-based polymer hydrogels. Fourier Transform Infrared Spectroscopy (FFIR) and amino acid analysis confirmed the peptide coupling to the polymer. Activated and control (unmodified) polymer matrices were stereotaxically implanted in the striata of rat brains, and two months later the brains were processed for immunohistochemistry using antibodies for glial acidic fibrillary protein (GFAP), laminin and neurofilaments. RGD-containing polymer matrices promoted stronger adhesion to the host tissue than the unmodified polymer matrices. In addition, the RGD-grafted polymer implants promoted and supported the growth and spread of GFAP-positive glial tissue onto and into the hydrogels. Neurofilament-positive fibers were also seen running along the surface of the polymer and, in some instances, penetrating the matrix. These findings are discussed in the context of using bioactive polymers as a new approach for promoting tissue repair and axonal regeneration of damaged structures of the central nervous system