Quantum Corrections in Quintessence Models

We investigate the impact of quantum fluctuations on a light rolling quintessence field from three different sources, namely, from a coupling to the standard model and dark matter, from its self-couplings and from its coupling to gravity. We derive bounds for time-varying masses from the change of vacuum energy, finding \Delta m_e/m_e << 10^{-11} for the electron and \Delta m_p/m_p << 10^{-15} for the proton since redshift z~2, whereas the neutrino masses could change of order one. Mass-varying dark matter is also constrained. Next, the self-interactions are investigated. For inverse power law potentials, the effective potential does not become infinitely large at small field values, but saturates at a finite maximal value. We discuss implications for cosmology. Finally, we show that one-loop corrections induce non-minimal gravitational couplings involving arbitrarily high powers of the curvature scalar R, indicating that quintessence entails modified gravity effects.Comment: 10 pages + appendix, added reference

Extracting partition statistics from semistructured data

The effective grouping, or partitioning, of semistructured data is of fundamental importance when providing support for queries. Partitions allow items within the data set that share common structural properties to be identified efficiently. This allows queries that make use of these properties, such as branching path expressions, to be accelerated. Here, we evaluate the effectiveness of several partitioning techniques by establishing the number of partitions that each scheme can identify over a given data set. In particular, we explore the use of parameterised indexes, based upon the notion of forward and backward bisimilarity, as a means of partitioning semistructured data; demonstrating that even restricted instances of such indexes can be used to identify the majority of relevant partitions in the data

1919, Photograph

https://digitalcommons.chapman.edu/mnmiller_collection/1002/thumbnail.jp

1919-01-24, Postcard

https://digitalcommons.chapman.edu/mnmiller_collection/1001/thumbnail.jp

1918-10-17, Mathias to Mary

https://digitalcommons.chapman.edu/mnmiller_collection/1000/thumbnail.jp

MIR-based in-situ measurement of Silicon crystal-melt interface

The project explores the a proposed MIR-based measurement system for measuring the deflection of the interface between the crystal and melt during production of mono-crystalline Silicon in the Czochralski process. The absorption spectrum is modeled and the specific absorption for a select set of wavelengths is estimated for temperatures approching 1687K. It was estimated that the intrinsic absorption edge, corresponding to a photon wavelength of 1.107um had an absorption coefficient of 1.56e+4 cm-1, while a wavelength of 2.55um had an absorption of 13.76 cm-1. The optimum wavelength for transmittance through Silicon at 1687K was determined to be 2.16um for extrinsic material doped with 2.8e+16 cm-3 concentration of Boron. The measurement using a transmittance scan with a wavelength of 2.55um of a three samples yielded results with a maximum deviation of 8.8% from the true deflection. A ray tracing method based on reflecting the beam of the interface yielded a maximum error of 11.6% with a mean result deviating by 1.6%

1918, Photograph

https://digitalcommons.chapman.edu/mnmiller_collection/1003/thumbnail.jp

Targeted radiotherapy of neuroblastoma: future directions

No abstract available

Remote Detection of Saline Intrusion in a Coastal Aquifer Using Borehole Measurements of Self-Potential

Funded by NERC CASE studentship . Grant Number: NE/I018417/1Peer reviewedPublisher PD