Spanwise Adaptive Wing - PTERA Flight Test

This is a technology which depends on a morphing vehicle wingtip. It allows one to replace the use of the rudder for some vehicles with the outer ailerons for control of the Dutch Roll Mode. Description of the PTERA flight test in support of the Spanwise Adaptive Wing flight research program

Basal characteristics of the main sticky spot on the ice plain of Whillans Ice Stream, Antarctica

Understanding the processes that affect streaming ice flow and the mass balance of glaciers and ice sheets requires sound knowledge of their subglacial environments. Previous studies have shown that an extensive deformable subglacial sediment layer favors fast ice-stream flow. However, areas of high basal drag, termed sticky spots, are of particular interest because they inhibit the fast flow of the overriding ice. The stick-slip behavior of Whillans Ice Stream (WIS) is perhaps the most conspicuous manifestation of a subglacial sticky spot. We present new ice-thickness and seismic-reflection measurements collected over the main sticky spot in the ice plain of WIS, allowing us to elucidate its role in the behavior of the ice stream. Ice-thickness and surface-elevation data show that the sticky spot occupies a subglacial topographic high. Water flow in response to the hydrological potential gradient will be routed around the sticky spot if effective pressures are similar on the sticky spot and elsewhere. The seismic experiment imaged a laterally continuous basal layer approximately 6 m thick, having compressional wave velocities of greater than 1800 m s−1 and density greater than 1800 kg m−3, indicative of a till layer that is stiffer than corresponding till beneath well-lubricated parts of the ice stream. This layer likely continues to deform under the higher shear stress of the sticky spot, and some water may be pumped up onto the sticky spot during motion events

Troughs developed in ice-stream shear margins precondition ice shelves for ocean-driven breakup

Floating ice shelves of fast-flowing ice streams are prone to rift initiation and calving originating along zones of rapid shearing at their margins. Predicting future ice-shelf destabilization under a warming ocean scenario, with the resultant reduced buttressing, faster ice flow, and sea-level rise, therefore requires an understanding of the processes that thin and weaken these shear margins. Here, we use satellite data to show that high velocity gradients result in surface troughs along the margins of fast-flowing ice streams. These troughs are advected into ice-shelf margins, where the locally thinned ice floats upward to form basal troughs. Buoyant plumes of warm ocean water beneath ice shelves can be focused into these basal troughs, localizing melting and weakening the ice-shelf margins. This implies that major ice sheet drainages are preconditioned for rapid retreat in response to ocean warming.</p

Characteristics of the sticky spot of Kamb Ice Stream, West Antarctica

Amplitude analysis of reflection seismic data reveals the presence of highly variable bed conditions under the main sticky spot and adjacent regions of the Kamb Ice Stream (KIS—formerly ice stream C). The sticky spot, which is a zone of bed that imparts high basal resistance to ice flow, is situated on a local topographic high composed of consolidated sediments or sedimentary rock. Any meltwater draining from upglacier along the base of the ice is routed around the sticky spot. The ice over the sticky spot includes, in at least some places, a seismically detectable basal layer containing a low concentration of debris, which locally thickens to 40 m over a topographic low in the bed. The ice-contact basal material ranges from dilated and highly porous to more-compacted and stiff, and perhaps locally frozen. The softer material is preferentially in topographic lows, but there is not a one-to-one correspondence between basal character and basal topography. We speculate that the 40-m-thick frozen-on debris layer formed by glaciohydraulic supercooling of lake-drainage events along a basal channel during the former, active phase of the ice stream. We also speculate that loss of lubricating water, perhaps from piracy upstream, contributed to the slowdown of the ice stream, with drag from the sticky spot playing an important role, and with the basal heterogeneity greatly increasing after the slowdown of the ice stream

Prospective Associations Between Boys' Substance Use and Problem Behavior Histories and Their Facial Trustworthiness in Adulthood

Introduction: People whose faces look untrustworthy tend to receive harsher social evaluations, including more severe criminal sentences. Yet little is known about how much facial trustworthiness reflects individuals’ behavioral histories. We examined whether adolescent histories of delinquency and substance use predict strangers’ perceptions of young men’s facial trustworthiness. Methods: Boys (n = 206) recruited from schools with higher juvenile crime rates were assessed repeatedly from ages 10-24 years, including arrest records and self-reported delinquency and substance use. Coders blind to the study’s purpose rated participants’ facial trustworthiness from photographs taken at ages 14 and 24; parent-reported childhood family income and coder ratings of attractiveness and positive affect at age 24 were considered as controls. Results: Facial trustworthiness at age 24 (but not age 14) negatively correlated with all measures of problem behavior. Yet, self-reported tobacco use occasions from ages 12-23 had the strongest association with facial trustworthiness at age 24, a relation that persisted when controlling for arrests and delinquency from ages 12-23, other substance use, family income, ratings of age-24 positive facial affect, attractiveness, and age-14 facial trustworthiness (β = -.29, 95% CI [-.42, -.15], p < .001). Discussion: Although boys’ early facial trustworthiness did not relate to their later problem behavior, men with histories of more delinquency and tobacco use appeared less facially trustworthy as adults. Appearance-related biases may have forensic and healthcare implications for young men. Additionally, prevention efforts could leverage information about the early impacts of tobacco use on appearance

First Incursion of Salmonella enterica Serotype Typhimurium DT160 into New Zealand

An outbreak of human Salmonella enterica serotype Typhimurium DT160 infection in New Zealand was investigated from May to August 2001. Handling of dead wild birds, contact with persons with diarrheal illness, and consumption of fast food were associated with infection. Contaminated roof-collected rainwater was also detected

161. The Potential Role of Extensor Muscle Fatigue in the Onset of Intervertebral Disc Degeneration: A Novel In Vivo Model

BACKGROUND CONTEXT: Occupation is strongly correlated to low back pain (LBP). Specific occupational activities associated with low back pain include poor posture, whole body vibration, and repetitive lifting. These activities have a common link: they result in fatigue of the primary spinal extensor musculature. This fatigue may lead to increased intervertebral loading - a stimulus for disc degeneration. If true, this association could provide a vital connection between detrimental physical activities and LBP. However, the link between muscle fatigue and increased load across the disc space has never been quantified in vivo. PURPOSE: The purpose of this study was to develop and test a wireless multi-axial force-sensing implant and large animal model of primary extensor muscle fatigue. Combined, these tools allow measurement of in vivo spinal forces during muscle fatigue to quantify changes in spine loading

Freezing of ridges and water networks preserves the Gamburtsev Subglacial Mountains for millions of years

Once an ice sheet grows beyond a critical thickness, the basal thermal regime favors melting and development of subglacial water networks. Subglacial water is necessary for bedrock erosion, but the exact mechanisms that lead to preservation of subglacial topography are unclear. Here we resolve the freezing mechanisms that lead to long-term, high-altitude preservation across the Gamburtsev Subglacial Mountains in East Antarctica. Analyses of a comprehensive geophysical data set reveal a large-scale water network along valley floors. The ice sheet often drives subglacial water up steep topography where it freezes along high ridges beneath thinner ice. Statistical tests of hypsometry show the Gamburtsevs resemble younger midlatitude mountains, indicating exceptional preservation. We conclude that the Gamburtsevs have been shielded from erosion since the latest Eocene (∼34 Ma). These freezing mechanisms likely account for the spatial and temporal patterns of erosion and preservation seen in other glaciated mountain ranges