An overview of electromagnetic interference problems in spacecraft

Electromagnetic Interference Workshop held at JPL /Feb., 1968/ permitted an exchange of information on electromagnetic interference problems encountered in aerospace programs. The experiences related at this workshop dealt primarily with Surveyor, Lunar Orbiter, OGO, ATS, and Mariner unmanned programs

Mariner Mars spacecraft magnetic contamination Status report

Magnetic field intensity measurements for Mariner spacecraft component

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

The development of magmatism along the Cameroon Volcanic Line: evidence from seismicity and seismic anisotropy

The Cameroon Volcanic Line (CVL) straddles the continent-ocean boundary in West Africa but exhibits no clear age progression. This renders it difficult to explain by traditional plume/plate motion hypotheses; thus, there remains no consensus on the processes responsible for its development. To understand better the nature of asthenospheric flow beneath the CVL, and the effects of hotspot tectonism on the overlying lithosphere, we analyze mantle seismic anisotropy and seismicity. Cameroon is relatively aseismic compared to hotspots elsewhere, with little evidence for magmatism-related crustal deformation away from Mount Cameroon, which last erupted in 2000. Low crustal Vp/Vs ratios (?1.74) and a lack of evidence for seismically anisotropic aligned melt within the lithosphere both point toward a poorly developed magmatic plumbing system beneath the CVL. Null SKS splitting observations dominate the western continental portion of the CVL; elsewhere, anisotropic fast polarization directions parallel the strike of the Precambrian Central African Shear Zone (CASZ). The nulls may imply that the convecting upper mantle beneath the CVL is isotropic, or characterized by a vertically oriented olivine lattice preferred orientation fabric, perhaps due to a mantle plume or the upward limb of a small-scale convection cell. Precambrian CASZ fossil lithospheric fabrics along the CVL may have been thermomechanically eroded during Gondwana breakup ?130?Ma, with an isotropic lower lithosphere subsequently reforming due to cooling of the slow-moving African plate. Small-scale lithospheric delamination during the 30?Ma recent development of the line may also have contributed to the erosion of the CASZ lithospheric fossil anisotropy, at the same time as generating the low-volume alkaline basaltic volcanism along the CV

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

Turf wars: experimental tests for alternative stable states in a two-phase coastal ecosystem

Alternative stable states have long been thought to exist in natural communities, but direct evidence for their presence and for the environmental switches that cause them has been scarce. Using a combination of greenhouse and field experiments, we investigated the environmental drivers associated with two distinctive herbaceous communities in coastal ecosystems in New Zealand. In a mosaic unrelated to micro-topography, a community dominated largely by native turf species (notably Leptinella dioica, Samolus repens, and Selliera radicans) alternates with vegetation comprising exotic (i.e., nonnative) pasture species (notably Agrostis stolonifera, Holcus lanatus, Lolium perenne, and Trifolium repens). The species of these two communities differ in functional characters related to leaf longevity and growth rate, and occupy soils of differing nitrogen levels. Both spatial and environmental factors influenced the species composition locally. Reciprocal transplants of soil, with and without associated vegetation, showed that a native turf community developed when sward or soil from either community was bounded by turf, and a pasture community developed when sward or soil from either community was surrounded by pasture. In artificial mixed communities in the greenhouse, turf was able to invade the pasture community where the vegetation was clipped to simulate grazing, and also where Trifolium was removed and/or salt spray was applied. The pasture community invaded the turf where Trifolium was present or nitrogen was added. These results were supported by trends in experimentally manipulated field plots, where the amount of turf cover increased when nitrogen was kept low and when salt spray was applied, whereas pasture cover increased in the absence of salt spray. Thus, persistence of the native turf community is dependent on grazing, both directly and via its effect on keeping nitrogen levels low by excluding the exotic, nitrogen-fixing Trifolium, and by exposing the vegetation to salt spray. If any of these factors change, there could be a state change to pasture dominance that might be resistant to reversion to turf. Managing such coastal herbaceous communities therefore requires an understanding of the environmental and species characteristics that maintain alternative states

The nature of vegetation science

Fil: Partel, Meelis. University of Tartu. Institute of Ecology and Earth Sciences; EstoniaFil: Chiarucci, Alessandro. University of Siena. Department of Environmental Science ‘‘G. Sarfatti’’. BIOCONNET, Biodiversity and Conservation Network; ItaliaFil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); Argentina; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Wilson, J. Bastow. University of Otago. Botany Department ; Nueva Zeland

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 (PSD) measurements suggest that 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 30 m 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 meters 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 PSD values for all stations to facilitate comparison with any future urban seismic deployments

Reflective Learning within a Counselor Education Curriculum

The literature on counselor education and supervision acknowledged the importance of self-awareness and self-reflection in supervision. As counselor educators we emphasized a need to prepare students for reflective practice prior to the practicum experience. In order to investigate how active learning and opportunities were being infused, we conducted an inquiry into the core curriculum of a Community Counseling program. Learning activities were categorized and charted according to the eight core areas of counselor education. This case study analysis provides a guide for a curriculum review of reflective learning and a catalyst for further inquiry