Two-Party Competition with Persistent Policies

This paper studies the Markov perfect equilibrium outcomes of a dynamic game of electoral competition between two policy-motivated parties. I model incumbent policy persistence: parties commit to implement a policy for their full tenure in office, and hence in any election only the opposition party renews its platform. In equilibrium, parties alternate in power and policies converge to symmetric alternations about the median voter's ideal policy. Parties' disutility from opponents' policies leads to alterna- tions that display bounded extremism; alternations far from the median are never limits of equilibrium dynamics. Under a natural restriction on strategies, I find that robust long-run outcomes display bounded moderation; alternations close to the median are reached in equilibrium only if policy dynamics start there. I show that these results are robust to voters being forward-looking, the introduction of term limits, costly policy adjustments for incumbents, and office benefits.

Keeping Your Options Open

In standard models of experimentation, the costs of project development consist of (i) the direct cost of running trials as well as (ii) the implicit opportunity cost of leaving alternative projects idle. Another natural type of experimentation cost, the cost of holding on to the option of developing a currently inactive project, has not been studied. In a (multi-armed bandit) model of experimentation in which inactive projects have explicit maintenance costs and can be irreversibly discarded, I fully characterise the optimal experimentation policy and show that the decision-maker's incentive to actively manage its options has important implications for the order of project development. In the model, an experimenter searches for a success among a number of projects by choosing both those to develop now and those to maintain for (potential) future development. In the absence of maintenance costs, the optimal experimentation policy has a 'stay-with-the-winner' property: the projects that are more likely to succeed are developed first. Maintenance costs provide incentives to bring the option value of less promising projects forward, and under the optimal experimentation policy, projects that are less likely to succeed are sometimes developed first. A project development strategy of 'going-with-the-loser' strikes a balance between the cost of discarding possibly valuable options and the cost of leaving them open.

The Cell Wall as a Barrier Against Water Loss and Plant Pathogens

The ability to survive a range of stresses is crucial to the survival of plants. Structural modifications in the cell wall through pectin cross linkages may be key to mitigating damage caused by stress. Pectin reduces cell wall permeability and increases rigidity through calcium ion crosslinks to carboxylate ions in galacturonic acid residues in homogalacturonan, and boron crosslinks to apiosyl residues in rhamnogalacturonan II side chains. The objective of this research was to understand the influence of calcium and boron in vitro, and how changes in viscosity and rigidity may translate to resistance to dehydration and fungal pathogens in Allium spp. and Arabidopsis pectin methylesterase/boron mutant genotypes. Allium spp. served as an ideal model to study dehydration stress as the cells are large and a single layer of epidermal cells can be easily separated. Arabidopsis was useful given the availability of mutant genotypes. CaCl2 and H3BO3 were both found to significantly (p0.05) and Colletotrichum higginsianum infection (p<0.05). Because of the mechanism of infection, the rapid rate of Colletotrichum higginsianum infection in bor1 is indicative of a weak cell wall. While the response to stress is highly complex, collectively this thesis indicates calcium, boron, pectin and the cell wall in general may play important but relatively under researched roles in plant resistance to both abiotic and biotic stress

Discrete brittle to distributed shearing; Results from analysis of the deep portions of the Cajon Pass Drill Hole

We performed systematic structural and geochemical analyses on a suite of cored rocks from the vertical Cajon Pass, California drill hole to characterize the deformation and alteration of fault-related rocks. The drill hole lies 4 km northeast of the San Andreas Fault (SAF), and observations of deformed crystalline rock in core and outcrop provide a sample of a 5-km vertical column adjacent to the steeply dipping Cleghorn fault and span the brittle to semi-brittle deformational regime at hydrothermal conditions. The rocks in the upper 500 m of the borehole are composed of sandstones and granitoid augen gneiss, with narrow fault and fracture zones coated with thin seams of laumontite. Below 500 m depth in the core, tonalite gneiss and migmatite contain well-developed discrete brittle faults and fracture zones. Thirty-seven faults are recognized in the core and borehole data; eleven are newly identified here, eight were previously identified in the core, and the remainder are interpreted from borehole image log data. The size of the fault zones intersected by the core controls the extent and nature of deformation. Distribution of faults in the core increase with depth, and fracture densities are greater around fault zones. In the upper 2600 m of the hole, the faults and fractures are typically narrow with thin coatings of alteration products. Prominent fault zones at 2100 - 2300 and 2500 - 2600 m measured depth dip moderately to steeply, and within this fault distributed shearing and alteration textures are common. Microstructures in these fault zones primarily include shear fractures containing a matrix of laumontite with angular to sub-angular clasts within the matrix and record multiple cycles of deformation and alteration. Laumontite mineralization indicates moderate- to high-temperature fluids interacting with the rocks throughout most of the column. The most significant fault observed in the core is an indurated, steep-dipping zone at 3,402 m depth that exhibits evidence of a mixture of brittle and semi-brittle deformation and abundant mineralization and alteration of potassium feldspar and epidote. This fault correlates well with the left-lateral steeply dipping Cleghorn fault, and reflects the interaction between hydrothermal metasomatic alteration and brittle fracture, cataclastic flow, to incipient plastic deformation processes at depth. The interpretation that the fault zone at the bottom of the hole is the Cleghorn fault agrees with stress orientation measurements made there by M D. Zoback and coworkers and indicates that the faults in the drill hole reflect active deformation and alteration associated with northeast-oriented maximum horizontal stress that may drive the left-lateral oblique motion on the Cleghorn fault. The data also show that damage zones associated with faults are present here, and may consist of mixed mode deformation, indicating a long-lived presence of the deformed and altered zones of reduced elastic moduli associated with faults. Simple modeling of the thermodynamics of syntectonic reactions in the fault zones indicate that earthquakes can be the source of heat to drive the reactions, and thus earthquake energy may be consumed in the fault core and damage zone by focused alteration

WikiGames : une plateforme de jeux dédiée à la validation d’une base de connaissances produite à partir de techniques d’extraction d’information ouverte

L’extraction d’information ouverte permet la création de larges collections de triplets relationnels à partir de corpus de textes non structurés. Ces larges collections de triplets extraits contiennent souvent une grande quantité de triplets bruités n’apportant aucune information utile. Ces collections peuvent atteindre des tailles rendant la validation manuelle trop longue pour être réalisées par un petit groupe de personnes en un temps convenable et il serait dans bien des cas trop dispendieux pour ces équipes d’engager le personnel nécessaire pour cette tâche. L’utilisation de jeux à des fins de production participative a permis, lors de tâches similaires, de recueillir un grand ensemble de bénévoles. Nous nous sommes donc intéressés à inférer, à partir d’une de ces collections de triplets bruités qui fut précédemment générée à partir de techniques d’extraction d’information ouverte, un ensemble de connaissances potentiellement utiles et pertinentes et avons ensuite amorcé la validation de cette base de connaissances par l’intermédiaire d’une plateforme de jeux.Open information extraction techniques can generate a large amount of relation triplets from unstructured corpus of texts. These large collections of triplets often contain a good portion of noisy triplets that brings little to no usable information. These collections of triplets can become too large to be manually validated by most small teams in a reasonable amount of time and hiring the number of validators required for such task would be too costly for most teams. The use of games as a crowdsourcing tool has shown great success in acquiring a large pool of volunteer for the realization of similar tasks. We have therefore looked into the extraction of a set of useful knowledge from a rather large and noisy relation triplets collection that was previously extracted using an open information extraction tool. We have then started the process of validating the resulting knowledge base with the help of a games with a purpose platform

iTunes U

iTunes U is a powerful distribution system for everything from lectures to language lessons, films to labs, audiobooks to tours. It is an innovative way to get educational content into the hands of students. Content is accessible on all desktop platforms (Mac, PC, Unix) as well as the iFamily of devices (iPad, iPod Touch, iPhone). Come learn how Bristol Community College has branded our iTunes U site, and is using it to allow faculty to handle their own multimedia content

VACUUM ULTRA-VIOLET STUDIES USING ELECTRON IMPACT EXCITATION.

This work presents emission cross section following electron-impact on helium, hydrogen, sulfur hexafluoride, nitrogen, and argon. Specifically, we studied the following emissions. The He(\u27+) 2p (---\u3e) 1s 30.4 nm emission, the numerous emissions from the neutral and singly ionized atomic fragments of SF(,6), the 120 nm emission from N(,2), and the Lyman series emissions from both atomic and molecular hydrogen. The most important aspect of the hydrogen work was the determination of the H(,2) Lyman alpha emission cross section. Use of the Lyman series from atomic hydrogen for the calibration of optical equipment in the 90 to 122 nm region was also investigated. To illustrate the technique, emission cross sections of the argon resonance lines near 105 nm and the argon ion lines near 93 nm were determined. Excitation functions for the He(\u27+) 30.4 nm emission and for various fluorine and sulfur emissions (along with some appearance potentials) were also obtained. A value of (7.5 (+OR-) 1.6) x 10(\u27-19) cm(\u272) at 200 eV is found for the He(\u27+) 30.4 nm transition. For the dissociative excitation of SF(,6) the largest emission cross sections belonged to the FI transitions at 95.5 nm (2.03 x 10(\u27-18) cm(\u272) at 200 eV) and 97.5 nm (1.46 x 10(\u27-18 )cm(\u272) at 200 eV). The maximum SI and SII emission cross sections are approximately 1 x 10(\u27-19) cm(\u272) and the strongest FII emission cross sections are approximately 1 x 10(\u27-20) cm(\u272). The NI 120 nm emission cross section is (2.98 (+OR-) 0.36) x 10(\u27-18) cm(\u272). Our value for the H(,2) Lyman alpha emission cross section is (7.08 (+OR-) 0.58) x 10(\u27-18) cm(\u272) at 100 eV. The emission cross sections for the argon resonance lines at 104.8 nm and 106.7 nm are (12.8 (+OR-) 1.3) x 10(\u27-18) cm(\u272) and (5.5 (+OR-) 0.8) x 10(\u27-18) cm(\u272) respectively. For the argon ion lines at 92 nm and 93.5 nm they are (5.6 (+OR-) 0.5) x 10(\u27-18) cm(\u272) and (2.3 (+OR-) 0.2) x 10(\u27-18) cm(\u272) respectively.Dept. of Physics. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1986 .F673. Source: Dissertation Abstracts International, Volume: 47-09, Section: B, page: 3816. Thesis (Ph.D.)--University of Windsor (Canada), 1986

eLearning Live

BigBlueButton is an open source web conferencing system similar to DimDim, Elluminate, and Wimba. This solution runs on Mac, Unix, or PC computers, and is very simple and quick to install and configure. Faculty have found to be the simplest interface for web collaboration. Come take a look at how we are using it at Bristol Community College to supplement and support eLearning and face-to-face courses

Dynamic project selection

We study a normative model of an internal capital market that a company uses to choose between its two divisions’ projects. Each project’s value is initially unknown to all, but can be dynamically learned by the corresponding division. Learning can be suspended or resumed at any time and is costly. We characterize an internal capital market that maximizes the company’s expected cash flow