Turbulence in the solar wind

The solar wind provides a unique natural "laboratory" in which plasma turbulence may be investigated in-situ. Turbulence is statistically reproducible. Thus, in this thesis we investigate plasma turbulence in the solar wind through the statistical study of magnetic field observations. In particular, we investigate single-satellite time-series of the magnetic field. We discuss hydrodynamic turbulence, and make parallels between hydrodynamic and magnetohydrodynamic turbulence. In hydrodynamic turbulence a unique scaling relation may be determined from dimensional analysis. Importantly, one may not derive a unique scaling relation for magnetohydrodynamic turbulence from dimensional analysis. Therefore, comparison of observations and turbulence models are key to determining the underlying physics for specific plasma parameters. The inertial range is a range of scales over which energy cascades from large to small temporal-spatial scales. This thesis will predominantly be focused on the anisotropy and scaling of the inertial range within the solar wind. We investigate how sampling a solenoid field, i.e. . B = 0, with a single satellite produces an apparent nonaxisymmetry with respect to the background magnetic field. We also investigate how time-series discontinuities produced by non-turbulent structures alter the statistical analysis of various anisotropy measures. We will find that the commonly held picture of the solar wind, that specific temporal-spatial scales have a distinct physical origin, is an over simplified model. We will show that non-turbulent structures must be removed from the observations in order to analysis the statistics of the turbulence accurately. The work in this thesis helps to constrain theories of plasma turbulence where there is a background magnetic field with a greater magnitude than the root-mean-square magnitude of the turbulent fluctuations

Can Inflation be Falsified?

Despite its central role in modern cosmology, doubts are often expressed as to whether cosmological inflation is really a falsifiable theory. We distinguish two facets of inflation, one as a theory of initial conditions for the hot big bang and the other as a model for the origin of structure in the Universe. We argue that the latter can readily be excluded by observations, and that there are also a number of ways in which the former can find itself in conflict with observational data. Both aspects of the theory are indeed falsifiable.Comment: 7 pages LaTeX file with two figures incorporated by epsf. Fifth Prize in Gravity Research Foundation Essay Competition. To appear, General Relativity and Gravitatio

Acute military psychiatric casualties from the war in Iraq

Background: The view that most military personnel evacuated from war zones are suffering from combat stress reactions, or are otherwise traumatised by the horrors of war, has an impact on all aspects of military psychiatry. Aims: To delineate the reasons for psychiatric aeromedical evacuation from Iraq from the start of build-up of UK forces in January 2003 until the end of October that year, 6 months after the end of formal hostilities. Method: A retrospective study was conducted of field and in-patient psychiatric assessments of 116 military personnel evacuated to the UK military psychiatric in-patient facility in Catterick Garrison. Results: Evacuees were mainly non-combatants (69%). A significant proportion were in reserve service (21%) and had a history of contact with mental health services (37%). Only 3% had a combat stress reaction. In over 85% of cases evacuation was for low mood attributed to separation from friends or family, or difficulties adjusting to the environment. Conclusions: These findings have implications especially for screening for suitability for deployment, and for understanding any longer-term mental health problems arising in veterans from Iraq

What does engagement mean to participants in longitudinal cohort studies?:A qualitative study

Abstract Background Engagement is important within cohort studies for a number of reasons. It is argued that engaging participants within the studies they are involved in may promote their recruitment and retention within the studies. Participant input can also improve study designs, make them more acceptable for uptake by participants and aid in contextualising research communication to participants. Ultimately it is also argued that engagement needs to provide an avenue for participants to feedback to the cohort study and that this is an ethical imperative. This study sought to explore the participants’ experiences and thoughts of their engagement with their birth cohort study. Methods Participants were recruited from the Children of the 90s (CO90s) study. Qualitative semi-structured interviews were conducted with 42 participants. The interviews were transcribed verbatim, and uploaded onto Nvivo software. They were then analysed via thematic analysis with a constant comparison technique. Results Participants’ experiences of their engagement with CO90s were broadly based on three aspects: communication they received from CO90s, experiences of ethical conduct from CO90s and receiving rewards from CO90s. The communication received from CO90s, ranged from newsletters explaining study findings and future studies, to more personal forms like annual greeting cards posted to each participant. Ethical conduct from CO90s mainly involved participants understanding that CO90s would keep their information confidential, that it was only involved in ‘good’ ethical research and their expectation that CO90s would always prioritise participant welfare. Some of the gifts participants said they received at CO90s included toys, shopping vouchers, results from clinical tests, and time off from school to attend data collection (Focus) days. Participants also described a temporality in their engagement with CO90s and the subsequent trust they had developed for the cohort study. Conclusion The experiences of engagement described by participants were theorized as being based on reciprocity which was sometimes overt and other times more nuanced. We further provide empirical evidence of participants’ expectation for a reciprocal interaction with their cohort study while highlighting the trust that such an interaction fosters. Our study therefore provides key insights for other cohort studies on what participants value in their interactions with their cohort studies

Embedding Innovation Process And Methodology In Engineering Technology And Business Management And Marketing Courses

For many business segments, true “out of the box” innovation occurs in entrepreneurial companies where the founders aren’t hindered with the research paradigms established by mainstream businesses. The founders of these companies, many times technologists and scientists, see the application of the technology long before potential customers develop an understanding of the capabilities that the new technology can bring to the marketplace. Many times these “new technology ideas” have been developed though modifying an existing dominant design (product or service) to meet an unforeseen market need or through the development of a new design that may become the new industry standard. The competitors of tomorrow may reside in radically different markets yet have the insight to envision the application or modification of an existing technology to a market segment that they are currently not involved in. Teaching engineering technology students techniques and visioning tactics related to the innovation process has been difficult. Several of the authors have experienced, both in the classroom and in industrial settings, that many engineering and engineering technology students see innovation as the application of engineering principals resulting in small incremental changes in a process. Although these changes may result in a more efficient process through increased productivity, reduced waste, faster cycle times, etcetera; continuous improvement projects many times do not generate the dramatic market changes seen with a new dominant design. In fact in many established industries, disruptive innovation is discouraged in favor of continuous innovation because of the uncertainty of the risk/reward quotient and the impact that failed experimentation (increased research and development costs) can have on Wall Street’s perception of a company. Our university recently merged the colleges of Business and Technology and Applied Sciences resulting in a cross-pollinated faculty and the establishment of courses in the graduate and undergraduate curriculum where business and engineering technology student’s work together on class projects, many of which involve an innovation component. It is interesting that many of the faculty who incorporate a discussion or exercise related to the innovation process in their classroom have had extensive experience in an industrial setting prior to joining the university faculty. Industry seasoned faculty bring their “real-world” experience to the classroom and challenge students to move beyond continuous improvement projects. In several cases, ideas generated in the classroom or through collaborative efforts between the business and technology faculty have resulted in prototypes being built in the laboratory for further testing of the prospective innovation. The presence of a technology-centered business incubator located within walking distance from campus provides students the opportunity to observe several high technology businesses that have developed new technology niches in established market segments. These businesses provide consulting opportunities for cross-disciplinary graduate student teams to observe the challenges of introducing a new technology to address previously met market needs through introduction of a superior product. The business incubator is further linked to a sister technology-centered business incubator in Europe providing students (graduate and undergraduate) the opportunity to evaluate if a new technology should be launched initially in the United States or Europe. The creation of these learning opportunities mimic the industrial setting where graduates will be required to operate in cross-disciplinary teams that may address global manufacturing and marketing decisions. This paper discusses the pedagogical approaches several faculty members have developed to introduce and cultivate a creative innovation process to undergraduate and graduate students enrolled in technology engineering and business marketing and management classes. These approaches include identifying unmet market niche opportunities, identifying technologies utilized in alternative markets that could be utilized for different market segments, classroom exercises to compel students to search existing patent literature, ideation and brainstorming exercises and researching business entities to identify their technology strategy and implementation plans

An examination of the precipitation delivery mechanisms for Dolleman Island, eastern Antarctic Peninsula

Copyright @ 2004 Wiley-BlackwellThe variability of size and source of significant precipitation events were studied at an Antarctic ice core drilling site: Dolleman Island (DI), located on the eastern coast of the Antarctic Peninsula. Significant precipitation events that occur at DI were temporally located in the European Centre for Medium-Range Weather Forecasting (ECMWF) reanalysis data set, ERA-40. The annual and summer precipitation totals from ERA-40 at DI both show significant increases over the reanalysis period. Three-dimensional backwards air parcel trajectories were then run for 5 d using the ECMWF ERA-15 wind fields. Cluster analyses were performed on two sets of these backwards trajectories: all days in the range 1979–1992 (the climatological time-scale) and a subset of days when a significant precipitation event occurred. The principal air mass sources and delivery mechanisms were found to be the Weddell Sea via lee cyclogenesis, the South Atlantic when there was a weak circumpolar trough (CPT) and the South Pacific when the CPT was deep. The occurrence of precipitation bearing air masses arriving via a strong CPT was found to have a significant correlation with the southern annular mode (SAM); however, the arrival of air masses from the same region over the climatological time-scale showed no such correlation. Despite the dominance in both groups of back trajectories of the westerly circulation around Antarctica, some other key patterns were identified. Most notably there was a higher frequency of lee cyclogenesis events in the significant precipitation trajectories compared to the climatological time-scale. There was also a tendency for precipitation trajectories to come from more northerly latitudes, mostly from 50–70°S. The El Niño Southern Oscillation (ENSO) was found to have a strong influence on the mechanism by which the precipitation was delivered; the frequency of occurrence of precipitation from the east (west) of DI increased during El Niño (La Niña) events

Observing Long Cosmic Strings Through Gravitational Lensing

We consider the gravitational lensing produced by long cosmic strings formed in a GUT scale phase transition. We derive a formula for the deflection of photons which pass near the strings that reduces to an integral over the light cone projection of the string configuration plus constant terms which are not important for lensing. Our strings are produced by performing numerical simulations of cosmic string networks in flat, Minkowski space ignoring the effects of cosmological expansion. These strings have more small scale structure than those from an expanding universe simulation - fractal dimension 1.3 for Minkowski versus 1.1 for expanding - but share the same qualitative features. Lensing simulations show that for both point-like and extended objects, strings produce patterns unlike more traditional lenses, and, in particluar, the kinks in strings tend to generate demagnified images which reside close to the string. Thus lensing acts as a probe of the small scale structure of a string. Estimates of lensing probablity suggest that for string energy densities consistant with string seeded structure formation, on the order of tens of string lenses should be observed in the Sloan Digital Sky Survey quasar catalog. We propose a search strategy in which string lenses would be identified in the SDSS quasar survey, and the string nature of the lens can be confirmed by the observation of nearby high redshift galaxies which are also be lensed by the string.Comment: 24 pages revtex with 12 postscript firgure

On the reliability of inflaton potential reconstruction

If primordial scalar and tensor perturbation spectra can be inferred from observations of the cosmic background radiation and large-scale structure, then one might hope to reconstruct a unique single-field inflaton potential capable of generating the observed spectra. In this paper we examine conditions under which such a potential can be reliably reconstructed. For it to be possible at all, the spectra must be well fit by a Taylor series expansion. A complete reconstruction requires a statistically-significant tensor mode to be measured in the microwave background. We find that the observational uncertainties dominate the theoretical error from use of the slow-roll approximation, and conclude that the reconstruction procedure will never insidiously lead to an irrelevant potential.Comment: 16 page LaTeX file with eight postscript figures embedded with epsf; no special macros neede

Fructan synthesis, accumulation, and polymer traits I:Festulolium chromosome substitution lines

The fructans found as storage carbohydrates in temperate forage grasses have a physiological role in regrowth and stress tolerance. They are also important for the nutritional value of fresh and preserved livestock feeds, and are potentially useful as feedstocks for biorefining. Seasonal variation in fructan content and the capacity for de novo fructan synthesis have been examined in a Festulolium monosomic substitution line family to investigate variation in the polymers produced by grasses in the ryegrass-fescue complex. There were significant differences between ryegrass and fescue. Fescue had low polymeric fructan content and a high oligomer/polymer ratio; synthesis of polymers longer than degree of polymerisation 6 (DP6) from oligomers was slow. However, extension of polymer length from DP10/DP20 upwards appeared to occur relatively freely, and, unlike ryegrass, fescue had a relatively even spread of polymer chain lengths above DP20. This included the presence of some very large polymers. Additionally fescue retained high concentrations of fructan, both polymeric and oligomeric, during conditions of low source/high sink demand. There were indications that major genes involved in the control of some of these traits might be located on fescue chromosome 3 opening the possibility to develop grasses optimised for specific applications