A follow-up study of families who declined treatment at a child guidance clinic

Thesis (M.S.)--Boston Universit

Modelling Bathymetric Uncertainty

Modelling depth measurement uncertainty during data collection and processing has become common practice since the release of S-44 4th Edition (IHO, 1998). Hydrographic Offices have also attempted to model uncertainty of legacy bathymetry in order to determine their fitness for various uses. Additional uncertainty can be introduced into representative bathymetry models by various gridding techniques that interpolate depths between measurements. This article reviews sources of measurement uncertainty, looks at methods for estimating uncertainty in legacy data sets and uncer-tainty that is introduced into bathymetry (digital elevation/depth) models (DEMs/DDMs) by gridding. Applications that could benefit from bathymetric/DEM/DDM uncertainty information include bridge risk management and tsunami inundation modelling.Keywords: bathymetry, uncertainty, digital elevation modelsLa modelización de la incertidumbre de las medidas de profundidad durante la recogida y el procesa-do de datos se ha convertido en una práctica común desde la publicación de la 4ª Edición de la S-44 (OHI, 1998). Los Servicios Hidrográficos han intentado también modelar la incertidumbre de la batimetría tradicional para determinar su idoneidad para varios usos. Puede introducirse una incerti-dumbre adicional en modelos de batimetría representativos mediante varias técnicas de reticulado que interpolan profundidades entre las medidas. Este artículo revisa las fuentes de incertidumbre en las medidas, estudia métodos para estimar la incertidumbre en las colecciones de datos tradicionales y la incertidumbre que se introduce en modelos de batimetría (elevación digital/profundidad) (DEMs/DDMs) mediante el reticulado. Las aplicaciones que podrían beneficiar de información relativa a una incertidumbre batimétrica/DEM/DDM incluyen la gestión de los riesgos de puente y la modelización de las inundaciones causadas por los tsunamis.Palabras clave: batimetría, incertidumbre, modelos de elevación digitales.La modélisation de l‘incertitude des mesures des profondeurs pendant la collecte et le traitement des données est devenue pratique commune depuis la publication de la 4ème Edition de la S-44 (OHI, 1998). Les Services hydrographiques se sont également efforcés de modéliser l’incertitude de la bathymétrie traditionnelle afin de déterminer leur aptitude à différentes utilisations. Une incertitude supplémentaire peut être introduite dans des modèles de bathymétrie représentatifs au moyen de différentes techniques de quadrillage qui interpolent les profondeurs entre les mesurages. Cet article passe en revue les sources d‘incertitude dans les mesurages, examine les méthodes d‘estimation de l‘incertitude dans les ensembles de données traditionnels et l‘incertitude introduite dans les modèles d‘élévation ou de profondeurs numériques (DEM/DDM) bathymétriques à l‘aide du quadrillage. Les applications qui pourraient bénéficier d‘informations sur l‘incertitude bathymétrique/DEM/DDM incluent la gestion des risques sur la passerelle et la modélisation des inondations en cas de tsunami.Mots clés : bathymétrie, incertitude, modèles d’élévation numérique

A dynamic discrete dislocation plasticity method for the simulation of plastic relaxation under shock loading

In this article, it is demonstrated that current methods of modelling plasticity as the collective motion of discrete dislocations, such as two-dimensional discrete dislocation plasticity (DDP), are unsuitable for the simulation of very high strain rate processes (106 s-1 or more) such as plastic relaxation during shock loading. Current DDP models treat dislocations quasi-statically, ignoring the time-dependent nature of the elastic fields of dislocations. It is shown that this assumption introduces unphysical artefacts into the system when simulating plasticity resulting from shock loading. This deficiency can be overcome only by formulating a fully time-dependent elastodynamic description of the elastic fields of discrete dislocations. Building on the work of Markenscoff & Clifton, the fundamental time-dependent solutions for the injection and non-uniform motion of straight edge dislocations are presented. The numerical implementation of these solutions for a single moving dislocation and for two annihilating dislocations in an infinite plane are presented. The application of these solutions in a two-dimensional model of timedependent plasticity during shock loading is outlined here and will be presented in detail elsewhere. © 2013 The Author(s) Published by the Royal Society. All rights reserved

Symmetries and Systematics of Doubly Heavy Hadrons

We discuss the extension of the superflavor symmetry of doubly heavy baryons to states which contain an excited heavy diquark, and we examine some of the consequences of this symmetry for the spectra of doubly heavy baryons and heavy mesons. We explore the ramifications of a proposed symmetry that relates heavy diquarks to doubly heavy mesons. We present a method for determining how the excitation energy of a system containing two heavy quarks will scale as one changes the strength of the interactions and the reduced mass of the system. We use this to derive consequences of the heavy diquark-doubly heavy meson symmetry. We compare these consequences to the results of a quark model as well as the experimental data for doubly and singly heavy mesons. We also discuss the possibility of treating the strange quark as a heavy quark and apply the ideas developed here to strange hadrons.Comment: 23 pages, 2 figures, and 17 tables include

Monte Carlo modelling of an x-ray chamber for providing inactivation exposures to viruses

The Monte Carlo radiation transport code MCNP6 has been used to model dosimetry for biological pathogen samples placed within a MultiRad 225 irradiation chamber, in order to inform virus deactivation protocols. Full characterisations of the photon spectra generated by the chamber's x-ray tube were achieved for both 190 and 220 kV potentials, with and without aluminium and copper beam filters of different thicknesses. Dose rate maps to air and water within the chamber were then derived, along with corresponding conversion coefficient data. The maps were determined for samples located both on a shelf and on a dry ice refrigeration chamber, at different distances from the source. The potential depth-dose profiles through samples were also investigated. The optimum choice of filter for use in virus inactivation procedures will rely on a compromise between dose homogeneity and dose rate

The effect of temperature on the elastic precursor decay in shock loaded FCC aluminium and BCC iron

EPSRC under Established Career Fellowship grant EP/N025954/1. Trinity College Cambridge Institute of Shock Physics Research Board and the Faculty of Engineering Dean’s office at the American University of Beiru

Predicting consumer biomass, size-structure, production, catch potential, responses to fishing and associated uncertainties in the world's marine ecosystems

Existing estimates of fish and consumer biomass in the world’s oceans are disparate. This creates uncertainty about the roles of fish and other consumers in biogeochemical cycles and ecosystem processes, the extent of human and environmental impacts and fishery potential. We develop and use a size-based macroecological model to assess the effects of parameter uncertainty on predicted consumer biomass, production and distribution. Resulting uncertainty is large (e.g. median global biomass 4.9 billion tonnes for consumers weighing 1 g to 1000 kg; 50% uncertainty intervals of 2 to 10.4 billion tonnes; 90% uncertainty intervals of 0.3 to 26.1 billion tonnes) and driven primarily by uncertainty in trophic transfer efficiency and its relationship with predator-prey body mass ratios. Even the upper uncertainty intervals for global predictions of consumer biomass demonstrate the remarkable scarcity of marine consumers, with less than one part in 30 million by volume of the global oceans comprising tissue of macroscopic animals. Thus the apparently high densities of marine life seen in surface and coastal waters and frequently visited abundance hotspots will likely give many in society a false impression of the abundance of marine animals. Unexploited baseline biomass predictions from the simple macroecological model were used to calibrate a more complex size- and trait-based model to estimate fisheries yield and impacts. Yields are highly dependent on baseline biomass and fisheries selectivity. Predicted global sustainable fisheries yield increases ≈4 fold when smaller individuals (< 20 cm from species of maximum mass < 1kg) are targeted in all oceans, but the predicted yields would rarely be accessible in practice and this fishing strategy leads to the collapse of larger species if fishing mortality rates on different size classes cannot be decoupled. Our analyses show that models with minimal parameter demands that are based on a few established ecological principles can support equitable analysis and comparison of diverse ecosystems. The analyses provide insights into the effects of parameter uncertainty on global biomass and production estimates, which have yet to be achieved with complex models, and will therefore help to highlight priorities for future research and data collection. However, the focus on simple model structures and global processes means that non-phytoplankton primary production and several groups, structures and processes of ecological and conservation interest are not represented. Consequently, our simple models become increasingly less useful than more complex alternatives when addressing questions about food web structure and function, biodiversity, resilience and human impacts at smaller scales and for areas closer to coasts