Impacts of elevated atmospheric ozone on peatland below-ground DOC characteristics

Rising concentrations of tropospheric ozone are having detrimental impacts on the growth of crop and forest species and some studies have reported inhibition of the allocation of carbon below ground. The effects of ozone on peatland ecosystems have received relatively little attention, despite their importance within the global carbon cycle. During this study, cores from a Welsh minerotrophic fen and ombrotrophic bog were exposed to four ambient/ elevated ozone concentration regimes representing current and predicted 2050 profiles. A large and significant reduction in the concentration of porewater dissolved organic carbon (DOC) was recorded in the fen cores exposed to the elevated ozone concentrations (up to −55%), with a concurrent shift to a higher molecularweight of the remaining soil carbon. No effects of ozone on DOC concentrations or characteristics were recorded for the bog cores. The data suggest higher ozone sensitivity of plants growing in the fen-type peatland, that the impacts on the vegetation may affect soil carbon characteristics through a reduction in root exudates and that theremay have been a shift in the source of substrate DOC for microbial consumption from vegetation exudates to native soil carbon. Theremay also have been a direct effect of ozone molecules reacting with soil organic matter after being transported into the soil through the aerenchyma tissue of the overlying vegetation. These qualitative changes in the soil carbon in response to elevated ozone may have important implications for carbon cycling in peatland ecosystems, and therefore climate change

Folklore and Knowledge. American Folklore Society "Big Questions and the Disciplines" Project

The Teagle Foundatio

Writing Lawa: Stimulating indigenous ownership of vernacular literacy through action research

The Eastern Lawa people of Northern Thailand have not had a practical or standardised method of writing their own language. This research began in response to an informal request that help be given to the teachers at Bo Luang school to write Lawa language using Thai script. The exploratory and informal nature of the project led me to use action research’s cyclical concept of action, followed by feedback, followed by planning for further action. This allowed for adjustments to both research goals and methods in response to the Eastern Lawa community. I was also able to document practical language development issues in the context of an ancient but rapidly changing indigenous Mon-Khmer community in Northern Thailand. I began with the traditional linguistic assumption that building a foundation for vernacular literacy would consist of three consecutive phases. A draft orthography would be prepared with the community. Community acceptance of this would allow a working orthography to be used by the teachers of Bo Luang school. The third phase would then be official regional or national recognition of a formal orthography. I also believed that community ownership was the key to all three phases. In reality I encountered a constant tension between trying to force the pathway of language development that I had envisaged and coming to terms with the linguistic and social situation which I discovered within the Bo Luang Lawa community. My plans for action research came to be grounded in a critical, reflexive ethnography. Community ownership became the major goal and the raison d’etre for my research instead of just an outcome of good language development practice. My initial emphasis on linguistic development has transformed into a desire to base both research goals and orthographic objectives on the history, identity and aspirations of the indigenous people. It is my intention that this thesis will be part of the growing body of work that recognises the limitations of Western empirical research models and the necessity for and practicality of alternative approaches. If you don’t know the words, ask your mother; if you don’t know the path, ask your father. (Traditional Lawa saying

Gate induced g-factor control and dimensional transition for donors in multi-valley semiconductors

The dependence of the g-factors of semiconductor donors on applied electric and magnetic fields is of immense importance in spin based quantum computation and in semiconductor spintronics. The donor g-factor Stark shift is sensitive to the orientation of the electric and magnetic fields and strongly influenced by the band-structure and spin-orbit interactions of the host. Using a multimillion atom tight-binding framework the spin-orbit Stark parameters are computed for donors in multi-valley semiconductors, silicon and germanium. Comparison with limited experimental data shows good agreement for a donor in silicon. Results for gate induced transition from 3D to 2D wave function confinement show that the corresponding g-factor shift in Si is experimentally observable.Comment: 4 pages, 4 figure

Quantum Cryptography Approaching the Classical Limit

We consider the security of continuous-variable quantum cryptography as we approach the classical-limit, i.e., when the unknown preparation noise at the sender's station becomes significantly noisy or thermal (even by as much as 10,000 times the variance of the vacuum mode). We show that, provided the channel transmission losses do not exceed 50%, the security of quantum cryptography is not dependent on the channel transmission, and is therefore, incredibly robust against significant amounts of excess preparation noise. We extend these results to consider for the first time quantum cryptography at wavelengths considerably longer than optical and find that regions of security still exist all the way down to the microwave.Comment: Letter (4 pages) followed by appendix (4 pages). Updated from published version with some minor correction

Quantum Process Tomography of the Quantum Fourier Transform

The results of quantum process tomography on a three-qubit nuclear magnetic resonance quantum information processor are presented, and shown to be consistent with a detailed model of the system-plus-apparatus used for the experiments. The quantum operation studied was the quantum Fourier transform, which is important in several quantum algorithms and poses a rigorous test for the precision of our recently-developed strongly modulating control fields. The results were analyzed in an attempt to decompose the implementation errors into coherent (overall systematic), incoherent (microscopically deterministic), and decoherent (microscopically random) components. This analysis yielded a superoperator consisting of a unitary part that was strongly correlated with the theoretically expected unitary superoperator of the quantum Fourier transform, an overall attenuation consistent with decoherence, and a residual portion that was not completely positive - although complete positivity is required for any quantum operation. By comparison with the results of computer simulations, the lack of complete positivity was shown to be largely a consequence of the incoherent errors during the quantum process tomography procedure. These simulations further showed that coherent, incoherent, and decoherent errors can often be identified by their distinctive effects on the spectrum of the overall superoperator. The gate fidelity of the experimentally determined superoperator was 0.64, while the correlation coefficient between experimentally determined superoperator and the simulated superoperator was 0.79; most of the discrepancies with the simulations could be explained by the cummulative effect of small errors in the single qubit gates.Comment: 26 pages, 17 figures, four tables; in press, Journal of Chemical Physic

THE EFFECT OF LOWER LIMB TRAINING ON MUSCULAR SUPPORT OF THE KNEE AND RISK OF ANTERIOR CRUCIATE LIGAMENT INJURY.

An intervention study was performed to investigate the effect of lower-limb training programs on knee muscle activation patterns and their potential to support the knee load during running and cutting manoeuvres. It is known that balance training can reduce ACL injury but the underlying mechanisms are unknown. The effects that strength training has on support for the knee joint during sporting manoeuvres are also not known. Analysis of activation levels and patterns of leg muscles during running, sidestepping and crossover-cutting manoeuvres prior to and following 12-week training programs revealed important results in terms of potential support of load on the ACL. Balance training increased co-contraction and supportive muscle activation patterns, as did the combination of machine and balance training to a lesser extent. The strength training programs tended to reduce co-contraction and were associated with changes which would lead to less stability of the knee during sporting manoeuvres. It is recommended that balance training should be implemented to reduce an athlete’s risk of ACL injury

Cerebral hemodynamics and oxidative metabolism dynamics observed by calibration of functional MRI

Thesis (Ph. D.)--Massachusetts Institute of Technology, Whitaker College of Health Sciences and Technology, 1998.Includes bibliographical references.by Timothy Lloyd Davis.Ph.D