Numerical Modelling of Sediment Delivery from Tidewater Glaciers to the Marine Environment

Glaciated fjords are dynamic sedimentary environments with high deposition rates, thus providing high-resolution sedimentary records of deglaciation. This thesis introduces two numerical models, SedBerg and SedPlume, developed to simulate marine sedimentation from tidewater glaciers for the dominant transport processes of icebergrafting and glacial meltwater plumes. Icebergs calved from tidewater glaciers contain sediment, which is released as the icebergs melt. The SedBerg Model utilises Monte Carlo based techniques to simulate the formation, drift and melt of a population of icebergs, and the subsequent deposition. Subaqueous and subaerial melt of the icebergs result in a continuous rainout of sediment with occasional sediment dumping from overturning events. Underlying the model are a number of parametric probability distributions to describe the stochastic behaviour of iceberg formation and dynamics. Parametric values of the probability density functions are found using maximum likelihood estimation from field observations. Turbid meltwater emerging from beneath a glacier into a fjord rises as a buoyant forced plume due to salinity and temperature contrasts with the ambient fjord water. The SedPlume Model utilises an integral model formulation for the conservation of volume, momentum, buoyancy and sediment mass along the path of a turbulent, entraining plume injected into stably stratified ambient fluid. The resulting system of non-linear ordinary differential equations are solved numerically using an adaptive stepsize fourth-order Runge-Kutta method. When the plume reaches the surface, it is treated as a radially spreading surface gravity current, for which exact solutions exist for the mass flux of sediment deposited. A case study is examined for each model. The SedBerg Model is applied to Kangerdlugssuaq Fjord in East Greenland, as an example of an iceberg-dominated depositional environment. The sedimentation rate due to iceberg rafting is simulated for Kangerdlugssuaq Fjord over the last 1500 years, with climatic, oceanographic and glacial conditions estimated from a mixture of present day measurements and inferences from the sedimentary record. The SedPlume Model is applied to McBride Inlet in Alaska, as an example of a glacial meltwater-dominated sedimentary environment, with input data and ice-proximal sedimentation rates taken from published data. The influence of various parameters on sediment deposition is investigated for each of the two models. For the SedBerg Model, the parameters considered are: iceberg size; temperature and depth of thermocline; and seeds of the random number generator for water and wind velocities. For the SedPlume Model, the parameters studied are: subglacial conduit radius and initial meltwater velocity; initial sand fraction; and ambient density gradient. The SedBerg and SedPlume Models enable quantitative assessments of the role and importance of different environmental and climatic conditions on the rate of deposition and the formation of distinctive marine deposits by tidewater glaciers

Where to Put Your Choker

The choke chain has become an indispensable aid in training dogs, but even the most time-hallowed practices deserve an occasional critical review. The author has recently completed an investigation into the uses and abuses of choke chains and failed to find any benefit from using a choker rather than a conventional leather collar. Indeed, there are some very considerable dangers and disadvantages associated with the device. These charges may sound like heresy to many dog trainers, but they may strike a sympathetic chord with others

¿Qué creen? No soy chismoso pero?. Mexican gossip : Affiliation or self-interest?

Whilst being taken more seriously, especially in anthropological and sociological studies, gossip is still often regarded trivial and of little academic research interest. Given that it is unstoppable, persistent and often enjoyable (Epstein, 2011), gossip has been examined in terms of function (e.g. talk about intimate matters to express shared values) and as a form of communication *for example, to express resistance (Goodman and Ben-Ze?ev, 1994). In this chapter, I examine the importance of gossip in the Mexican context. In Mexico, gossip has been examined in terms of function e.g. (Hagene, 2010), situation (Vázquez Garcia y Chávez Arellano, 2008) and resistance (Vázquez García 2007). I, however, study gossip from sociological-anthropological, social psychological and individual perspectives and evaluate how it is used to achieve affiliation and autonomy

Resonant electric dipole-dipole interactions between cold Rydberg atoms in a magnetic field

Laser cooled Rb atoms were optically excited to 46d Rydberg states. A microwave pulse transferred a fraction of the atoms to the 47p Rydberg state. The resonant electric dipole-dipole interactions between atoms in these two states were probed using the linewidth of the two-photon microwave transition 46d-47d. The presence of a weak magnetic field (approximately 0.5 G) reduced the observed line broadening, indicating that the interaction is suppressed by the field. The field removes some of the energy degeneracies responsible for the resonant interaction, and this is the basis for a quantitative model of the resulting suppression. A technique for the calibration of magnetic field strengths using the 34s-34p one-photon transition is also presented.Comment: Accepted for publication in Physical Review

Extracorporeal membrane oxygenation for severe respiratory failure in newborn infants.

BACKGROUND: Neonatal extracorporeal membrane oxygenation (ECMO) is a complex procedure of life support used in severe but potentially reversible respiratory failure in term infants. Although the number of babies eligible for ECMO is small and the use of ECMO invasive and potentially expensive, its benefits may be high. OBJECTIVES: To determine whether ECMO used for neonatal infants with severe respiratory failure is clinically and cost effective compared to conventional ventilatory support. SEARCH STRATEGY: The Cochrane Neonatal Group Specialised Register, the Cochrane Controlled Trials Register, and MEDLINE were searched for 1974 to 2007. SELECTION CRITERIA: All randomised trials comparing neonatal ECMO to conventional ventilatory support. DATA COLLECTION AND ANALYSIS: The authors independently evaluated the trials for methodological quality and appropriateness for inclusion in the Review (without consideration of their results) and independently extracted the data. MAIN RESULTS: The four trials (three USA and one UK) recruited clinically similar groups of babies. Two trials excluded infants with congenital diaphragmatic hernias. In two trials, transfer for ECMO implied transport over long distances. Two trials had follow-up information. One study included economic evaluation. The three USA trials had very small numbers of patients. Two trials used conventional randomisation with low potential for bias. Two used less usual designs, which led to difficulties in their interpretation. All four trials showed strong benefit of ECMO on mortality (typical RR 0.44; 95% CI 0.31 to 0.61), especially for babies without congenital diaphragmatic hernia (typical RR 0.33, 95% CI 0.21 to 0.53). The UK trial provided follow up information about death or severe disability, and cost-effectiveness, and showed benefit of ECMO at one year (RR 0.56, 95% CI 0.40 to 0.78), four years (RR 0.62, 95% CI 0.45 to 0.86), and seven years (RR 0.64, 95% CI 0.47 to 0.86). Overall nearly half of the children recruited had died or were severely disabled by seven years of age, reflecting the severity of their underlying conditions. A policy of ECMO is as cost-effective as other intensive care technologies in common use. AUTHORS' CONCLUSIONS: A policy of using ECMO in mature infants with severe but potentially reversible respiratory failure results in significantly improved survival without increased risk of severe disability. The benefit of ECMO for babies with diaphragmatic hernia is unclear. Further studies are needed to consider the optimal timing for introducing ECMO; to identify which infants are most likely to benefit; and to address the implications of neonatal ECMO during later childhood and adult life

Spectroscopic observation of resonant electric dipole-dipole interactions between cold Rydberg atoms

Resonant electric dipole-dipole interactions between cold Rydberg atoms were observed using microwave spectroscopy. Laser-cooled Rb atoms in a magneto-optical trap were optically excited to 45d Rydberg states using a pulsed laser. A microwave pulse transferred a fraction of these Rydberg atoms to the 46p state. A second microwave pulse then drove atoms in the 45d state to the 46d state, and was used as a probe of interatomic interactions. The spectral width of this two-photon probe transition was found to depend on the presence of the 46p atoms, and is due to the resonant electric dipole-dipole interaction between 45d and 46p Rydberg atoms.Comment: 5 pages, 3 figures. Accepted for publication in Phys. Rev. Lett. Titles and e-print numbers of references added to this versio

Developing core national indicators of public attitudes towards the police in Canada

Police departments regularly conduct public opinion surveys to measure attitudes towards the police. The results of these surveys can be used to shape and evaluate policing policy and practice. Yet the extant evidence base is hampered when people use different methods and when there is no common data standard. In this paper we present a set of 13 core national indicators that can be used by police services across Canada to ensure measurement quality and draw proper comparisons between regions and over time. Having identified a set of 50 survey questions through an expert consultation process, we field those items on a quota sample of 2527 Canadians. Our analysis of the survey data has three stages. First, we use confirmatory factor analysis to assess scale properties. Second, we use substitution analysis to identify 13 single indicators that ‘best stand in’ for each scale. Third, we use the set of 50 and the sub-set of 13 measures to test procedural justice theory for the first time in the Canadian context. Overall, those commissioning and managing public attitudes surveys can use the 13 core indicators as a conceptually-rich and empirically-validated tool through which to understand local survey data in the context of other municipal, provincial, territorial and national contexts

Torque Expression of Active and Passive Self-Ligating Orthodontic Brackets with Different Archwire Materials

This study aimed to compare torquing moments, engagement angles, and torsional stiffness generated by stainless steel (SS), titanium molybdenum alloy (TMA) and nickel titanium (NiTi) wires in three active self-ligating (ASL), one passive self-ligating (PSL), and a conventional twin orthodontic bracket system control. Brackets were tested in simulations of buccal and palatal root torque. A custom 3D printed testing apparatus was developed to measure torque. In general, the PSL and conventionally ligated systems generated significantly larger torquing moments than ASL systems, especially with stiffer wires and greater degrees of twist. Torquing direction only influenced torque expression with ASL systems. The PSL system demonstrated significantly smaller engagement angles than the ASL or twin bracket systems, especially with stiffer wires. Torsional stiffness values aligned with the expected modulus of elasticity of the given wire material. In addition to ligation modality, other aspects of bracket design likely contribute to these findings

Solidarity, supportiveness and creative language use in second-language interpersonal talk

Second-language (L2) users frequently demonstrate a strong interest in developing,\ud establishing and maintaining social relations with other L2 users through the medium of the\ud second language and I argue in this thesis that this is often achieved through a variety of\ud supportive and creative ways as interactants jointly construct interpersonal talk. My main\ud aim in this thesis is to explore the workings of L2-L2 interpersonal language use and, as a\ud secondary aim, to propose pedagogic intervention that will help the L2 learner to interact\ud supportively and creatively in the target language.\ud To develop this argument, I will build on the work on Aston and his description of how\ud successful social relations in the target language are negotiated through supportiveness and\ud solidarity and his use of the terms some and any (taken from Sacks, 1970-1971, and\ud Schenkein, 1978) to examine how the L2 user can participate as a distinct individual in L2-\ud L2 talk as opposed to interacting as an anonymous language user.\ud Second-language interpersonal talk is problematic because the language user seeks to\ud conform with others but, at the same time, wants to interact in creative ways. In discussing\ud creative language use, I build on the work of Mead and his distinction between the creative\ud I and the socially-conforming me and argue that L2-L2 creative language use is jointly\ud constructed between second-language users as they seek to develop successful social\ud relations.\ud I aim to analyse the problematic nature of L2 interpersonal language by examining data\ud collected on second-language users engaged in L2-L2 small talk in a target-language\ud context and through interviews with such users. While building on Aston's description of\ud solidarity and supportiveness in L2 interpersonal discourse, I also explore how creative\ud language use allows the second-language user to achieve successful social relations and, at\ud the same time, helps her to interact in her own distinctive way