Modeling the Impact of the Payload Alert Communications System (PACS) on the Accuracy of Conjunction Analysis

The Air Force Institute of Technology (AFIT) and the Air Force Research Laboratory (AFRL) are jointly developing a system known as the Payload Alert Communications System (PACS) whose purpose is to decrease the statistical uncertainty in the location of resident space objects (RSOs). PACS is designed to augment the Joint Space Operations Center\u27s (JSpOC) existing space object tracking capabilities which is expected to increase the accuracy of conjunction estimation. In the current PACS design, a small payload would be attached to certain RSOs prior their launch. It is envisioned that this payload would basically consist of a microcontroller, a Global Positioning System (GPS) receiver, a communication transceiver, and a power source. Once on orbit, the PACS payload would collect GPS position information and then periodically, or upon demand, transmit the orbital information back to JSpOC. In this thesis, a study is performed to determine how the accuracy of conjunction analysis performed by the JSpOC would be impacted when RSOs are equipped with PACS. This effort requires the development an initial PACS system architecture, formulation of the mathematical models used in conjunction analysis, and the simulation and analysis of conjunction analysis under various scenarios

Phenotypic mixing between strains of tobacco mosaic virus

RESP-640

In vivo phenotypic mixing between two strains of tobacco mosaic virus

RESP-632

The relative concentration of infective intact virus and RNA of four strains of tobacco mosaic virus as influenced by temperature

RESP-640

CAN-HK : An a priori crustal model for the Canadian Shield

ACKNOWLEDGMENTS The United Kingdom component of the Hudson Bay Lithospheric Experiment (HuBLE) was supported by the Natural Environment Research Council (NERC) Grant Number NE/F007337/1, with financial and logistical support from the Geological Survey of Canada (GSC), Canada-Nunavut Geoscience Office (CNGO), SEIS-UK (the seismic node of NERC), and the First Nations communities of Nunavut. J. Beauchesne and J. Kendall provided invaluable assistance in the field. I. D. B. was funded by the Leverhulme Trust and acknowledges support through Grant Number RPG-2013- 332. The authors thank three anonymous reviewers for their constructive comments.Peer reviewedPublisher PD

Characterizing Broadband Seismic Noise in Central London

Recordings made at five broadband seismometers, deployed in central London during the summer of 2015, reveal the wideband nature (periods, T, of between 0.01 and 100 s) of anthropogenic noise in a busy urban environment. Temporal variations of power spectral density measurements suggest transportation sources generate the majority of the noise wavefield across the entire wideband, except at the secondary microseismic peak (220 s) which are recorded across the city. We record a unique set of signals 30m above a subway (London Underground) tunnel interpreted as a short-period dynamic component, a quasi-static response to the train moving underneath the instrument, and a very long period (T>30 s) response to air movement around the tunnel network. A low-velocity clay and sand overburden tens of metres thick is shown to amplify the horizontal component wavefield at T ∼1 s, consistent with properties of the London subsurface derived from engineering investigations. We provide tabulated median power spectral density values for all stations, to facilitate comparison with any future urban seismic deployments

The Hudson Bay Lithospheric Experiment (HuBLE) : Insights into Precambrian Plate Tectonics and the Development of Mantle Keels

The UK component of HuBLE was supported by Natural Environment Research Council (NERC) grant NE/F007337/1, with financial and logistical support from the Geological Survey of Canada, Canada–Nunavut Geoscience Office, SEIS-UK (the seismic node of NERC), and First Nations communities of Nunavut. J. Beauchesne and J. Kendall provided invaluable assistance in the field. Discussions with M. St-Onge, T. Skulski, D. Corrigan and M. Sanborne-Barrie were helpful for interpretation of the data. D. Eaton and F. A. Darbyshire acknowledge the Natural Sciences and Engineering Research Council. Four stations on the Belcher Islands and northern Quebec were installed by the University of Western Ontario and funded through a grant to D. Eaton (UWO Academic Development Fund). I. Bastow is funded by the Leverhulme Trust. This is Natural Resources Canada Contribution 20130084 to its Geomapping for Energy and Minerals Program. This work has received funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no. 240473 ‘CoMITAC’.Peer reviewedPublisher PD

Boronic Acid Derivatives Targeting HIV-1

A series of novel boronic acid derivatives containing either a pyrimidine or purine base was synthesized. The preparation involved the condensation of 4-bromobutyl boronic acid with the appropriate base. These acyclic nucleosides were designed as potential antiviral agents especially targeting the human immunodeficiency virus. Two analogues, 6-chloro-9-(4-dihydroxyborylbutyl)purine and 2,6-dichloro-9-(4-dihydroxyborylbutyl)purine, exhibited EC50 values of 7.7 µM and 0.99 µM, respectively, in an HIV-1 syncytial plaque reduction assay

Variability and origin of seismic anisotropy across eastern Canada: evidence from shear-wave splitting measurements

Measurements of seismic anisotropy in continental regions are frequently interpreted with respect to past tectonic processes, preserved in the lithosphere as “fossil” fabrics. Models of the present-day sublithospheric flow (often using absolute plate motion as a proxy) are also used to explain the observations. Discriminating between these different sources of seismic anisotropy is particularly challenging beneath shields, whose thick (≥200 km) lithospheric roots may record a protracted history of deformation and strongly influence underlying mantle flow. Eastern Canada, where the geological record spans ∼3 Ga of Earth history, is an ideal region to address this issue. We use shear wave splitting measurements of core phases such as SKS to define upper mantle anisotropy using the orientation of the fast-polarization direction ϕ and delay time δt between fast and slow shear wave arrivals. Comparison with structural trends in surface geology and aeromagnetic data helps to determine the contribution of fossil lithospheric fabrics to the anisotropy. We also assess the influence of sublithospheric mantle flow via flow directions derived from global geodynamic models. Fast-polarization orientations are generally ENE-WSW to ESE-WNW across the region, but significant lateral variability in splitting parameters on a ≤100 km scale implies a lithospheric contribution to the results. Correlations with structural geologic and magnetic trends are not ubiquitous, however, nor are correlations with geodynamically predicted mantle flow directions. We therefore consider that the splitting parameters likely record a combination of the present-day mantle flow and older lithospheric fabrics. Consideration of both sources of anisotropy is critical in shield regions when interpreting splitting observations

Natural source zone depletion of LNAPL: A critical review supporting modelling approaches

Natural source zone depletion (NSZD) of light non-aqueous phase liquids (LNAPLs) includes partitioning, transport and degradation of LNAPL components. NSZD is being considered as a site closure option during later stages of active remediation of LNAPL contaminated sites, and where LNAPL mass removal is limiting. To ensure NSZD meets compliance criteria and to design enhanced NSZD actions if required, residual risks posed by LNAPL and its long term behaviour require estimation. Prediction of long-term NSZD trends requires linking physicochemical partitioning and transport processes with bioprocesses at multiple scales within a modelling framework. Here we expand and build on the knowledge base of a recent review of NSZD, to establish the key processes and understanding required to model NSZD long term. We describe key challenges to our understanding, inclusive of the dominance of methanogenic or aerobic biodegradation processes, the potentially changeability of rates due to the weathering profile of LNAPL product types and ages, and linkages to underlying bioprocesses. We critically discuss different scales in subsurface simulation and modelling of NSZD. Focusing on processes at Darcy scale, 36 models addressing processes of importance to NSZD are investigated. We investigate the capabilities of models to accommodate more than 20 subsurface transport and transformation phenomena and present comparisons in several tables. We discuss the applicability of each group of models for specific site conditions