Feasibility of hydromagnetic wave measurements on space shuttle

The feasibility of using a hydromagnetic wave sensor on the space shuttles was investigated. It was found that although existing sensors are inadequate in terms of resolution, dynamic range, and frequency range, they can be modified to make the necessary measurements. It is shown that since the sensor cannot be mounted on the shuttle itself because of high levels of magnetic noise, a free subsatellite that can be positioned and stabilized may be used for locating the hydromagnetic wave sensor. Other results show that studies of long period waves would require either an array of sensors in shuttle orbit or a long-term mapping of the crustal anomalies, and that effective wave studies would require at least two variably spaced sensors in shuttle orbit and one ground station

Magnetotail changes in relation to the solar wind magnetic field and magnetospheric substorms

An attempt is made to understand some of the magnetotail dynamics by using simultaneous observations from several satellites: Explorers 33 and 35 in the solar wind, IMP 4 in the near magnetotail (30 RE), ATS 1, and OGO 5 in the magnetosphere. It was observed that in the main lobes of the tail the magnetic field increases slowly when the interplanetary magnetic field turns southward, and can decrease slowly after a substorm. The plasma sheet changes indicate a thinning when the interplanetary magnetic field turns southward and an expansion when it turns northward. When combined with the plasma sheet expansion, which has been observed to follow a substorm, these results allow a schematic view of the relations between the changes in the orientation of the solar wind magnetic field, the substorms, and the changes in the tail parameters to be developed

Relative timing of substorm onset phenomena

[1] In this paper we examine the temporal ordering of midtail flow bursts, Pi2 pulsations, and auroral arc brightening at substorm onset. We present three substorm events for which the Geotail spacecraft was situated at local midnight, near the inner edge of the plasmasheet. We show that high-speed, convective Earthward directed plasma flows observed by Geotail occurred 1–3 min before auroral onset as observed by the Polar Visible Imaging System and Ultraviolet Imager auroral imagers on board the Polar spacecraft. We also show that the onsets of both nightside Pi2 pulsations and magnetic bay variations were simultaneous with auroral onset. We argue that these observations lend strong support to the flow burst-driven model of magnetotail dynamics. We also examine a high-latitude magnetic precursor to onset and show that it is likely due to the currents expected from the passage of a flow burst through the plasmasheet prior to substorm onset. Finally, we calculate an analytic expression for this current and show that it is unlikely to generate discrete auroral structures

Seasonal Distribution of Sage-Grouse in Hamlin Valley, Utah and the Effect of Fences on Grouse and Avian Predators

Greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) numbers have declined throughout the western US and are considered a species of concern in most of the eleven states that are within their range. Sage-grouse habitats have been reduced by approximately 44% since European settlement of the Western United States began (Miller et al. 2011). Loss of habitat has contributed to an average decline of sage-grouse populations by 33% across the range (Connelly and Braun 1997). To expand our knowledge of this species, I monitored 16 radio-collared sage-grouse captured from four leks in Hamlin Valley, Utah, USA in 2011 and 2012 to determine habitat use. The Hamlin Valley population was primarily one-stage migratory but non-migratory behaviors were also observed. Birds from at least one of the leks used seasonal habitats in neighboring Nevada. Sage-grouse evolved in habitats where infrastructure (e.g. vertical structures) was not common. Introduction of infrastructure, such as fences in their habitat, can cause direct mortality via collision but may also indirectly influence productivity by increasing artificial perches for avian predators (e.g. golden eagles (Aquila chrysaetos) , red-tailed hawks (Buteo jamaicensis), and common ravens (Corvus corax). This research focused on collision rates and increased potential for avian predation on two small populations on the southern portion of the range of current occupied sage-grouse habitat in southwestern vi Utah. During 2011-2012, over 450 km of fences were surveyed for signs of collision and use by avian predators during all seasons (breeding, fall migration, and winter). No sage-grouse collisions were observed suggesting that management for sage-grouse in small populations may be better focused on improving habitat and reducing other causes of mortality which may be more prevalent. Fence post width (i.e. the perching surface) was the best predictor of use as perch by avian predators. Additionally, areas farther from other natural perches, with a low density of surrounding vegetation, and fences constructed along defined habitat edges were used by avian predators more frequently. Results of this study suggest that managers should construct fences with small widths to deter avian predators and care should be taken to maintain contiguous vegetation on either side of the posts while maintaining low shrub density

Struggling Adolescent Writers Describe Their Writing Experience: A Descriptive Case Study

Four adolescents identified as struggling writers in an English language arts classroom were interviewed about their perceptions of a writing task--how they judged their capability to succeed, how they ranked their passion, persistence, and confidence about writing, and how they responded to classroom activity. Student perceptions of self-efficacy and the related self-beliefs of motivation and interest as well as self-regulation were stated and implied as students described a planning worksheet, instructional scaffolding, peer interactions, and ownership of their writing. Wersch\u27s view of mediated action and Engestrom\u27s model of activity systems were the lens through which the students\u27 descriptions were analyzed. Findings suggested surprisingly high self-efficacy despite low interest, contrasting attitudes between both school writing and their out-of-school writing, and the possibility that students labeled as struggling writers by their teachers may not see themselves as struggling

A procedure for accurate calibration of the orientation of the three sensors in a vector magnetometer

Procedures are described for the calibration of a vector magnetometer of high absolute accuracy. It is assumed that the calibration will be performed in the magnetic test facility of Goddard Space Flight Center (GSFC). The first main section of the report describes the test equipment and facility calibrations required. The second presents procedures for calibrating individual sensors. The third discusses the calibration of the sensor assembly. In a final section recommendations are made to GSFC for modification of the test facility required to carry out the calibration procedures

Multiple-satellite studies of magnetospheric substorms: Plasma sheet recovery and the poleward leap of auroral-zone activity

Particle observations from pairs of satellites (Ogo 5, Vela 4A and 5B, Imp 3) during the recovery of plasma sheet thickness late in substorms were examined. Six of the nine events occurred within about 5 min in locations near the estimated position of the neutral sheet, but over wide ranges of east-west and radial separations. The time of occurrence and spatial extent of the recovery were related to the onset (defined by ground Pi 2 pulsations) and approximate location (estimated from ground mid-latitude magnetic signatures) of substorm expansions. It was found that the plasma sheet recovery occurred 10 - 30 min after the last in a series of Pi bursts, which were interpreted to indicate that the recovery was not due directly to a late, high latitude substorm expansion. The recovery was also observed to occur after the substorm current wedge had moved into the evening sector and to extend far to the east of the center of the last preceding substorm expansion

A proof of concept for machine learning-based virtual knapping using neural networks

Prehistoric stone tools are an important source of evidence for the study of human behavioural and cognitive evolution. Archaeologists use insights from the experimental replication of lithics to understand phenomena such as the behaviours and cognitive capacities required to manufacture them. However, such experiments can require large amounts of time and raw materials, and achieving sufficient control of key variables can be difficult. A computer program able to accurately simulate stone tool production would make lithic experimentation faster, more accessible, reproducible, less biased, and may lead to reliable insights into the factors that structure the archaeological record. We present here a proof of concept for a machine learning-based virtual knapping framework capable of quickly and accurately predicting flake removals from 3D cores using a conditional adversarial neural network (CGAN). We programmatically generated a testing dataset of standardised 3D cores with flakes knapped from them. After training, the CGAN accurately predicted the length, volume, width, and shape of these flake removals using the intact core surface information alone. This demonstrates the feasibility of machine learning for investigating lithic production virtually. With a larger training sample and validation against archaeological data, virtual knapping could enable fast, cheap, and highly-reproducible virtual lithic experimentation