571 research outputs found
Geometric and chronologic evolution of the Verde and Payson Basins of Central Arizona and possible relationships to detachment faulting
The Transition Zone of Arizona and the structural basins therein have been poorly understood features from a structural standpoint. This is true both of their overall geometry as well as their formation. Yet these basins have developed within the last 13 million years and thus represent perhaps the most recent phase of development related to the extensional tectonics of the Basin and Range province. Recent work (Smith, 1984; Vance, 1983) as well as some older studies (Anderson and Creasy, 1985; Pedersen and Royce, 1970) provide data on the geometry of the Verde and Payson basins which can be used to constrain some hypotheses related to the development of these basins. The work of Cloos (1868), Anderson et. al. (1983), Wernicke and Burchfiel (1982) and Davis et. al. (l980) suggest a spatial and chronologic relation exists between planar high angle normal faults and low angle detachment faults. Perhaps one of the clearest examples from the Basin and Range area appears to be from seismic reflection profiles of the Sevier Desert Basin area of Utah (Fig. 1). These profiles suggest the existence fault-controlled extension basin development above it. Faults that appear either listric or planar intersect it from above
Atlas of Ocean Wealth
The Atlas of Ocean Wealth is the largest collection to date of information about the economic, social and cultural values of coastal and marine habitats from all over the world. It is a synthesis of innovative science, led by The Nature Conservancy (TNC), with many partners around the world. Through these efforts, they've gathered vast new datasets from both traditional and less likely sources.The work includes more than 35 novel and critically important maps that show how nature's value to people varies widely from place to place. They also illustrate nature's potential. These maps show that one can accurately quantify the value of marine resources. Further, by enumerating such values, one can encourage their protection or enhancement for the benefit of people all around the world. In summary, it clearly articulates not just that we need nature, but how much we need it, and where
From an automated flight-test management system to a flight-test engineer's workstation
The capabilities and evolution is described of a flight engineer's workstation (called TEST-PLAN) from an automated flight test management system. The concept and capabilities of the automated flight test management systems are explored and discussed to illustrate the value of advanced system prototyping and evolutionary software development
A NASA/RAE cooperation in the development of a real-time knowledge-based autopilot
As part of a US/UK cooperative aeronautical research program, a joint activity between the NASA Dryden Flight Research Facility and the Royal Aerospace Establishment on knowledge-based systems was established. This joint activity is concerned with tools and techniques for the implementation and validation of real-time knowledge-based systems. The proposed next stage of this research is described, in which some of the problems of implementing and validating a knowledge-based autopilot for a generic high-performance aircraft are investigated
The use of an automated flight test management system in the development of a rapid-prototyping flight research facility
An automated flight test management system (ATMS) and its use to develop a rapid-prototyping flight research facility for artificial intelligence (AI) based flight systems concepts are described. The ATMS provides a flight test engineer with a set of tools that assist in flight planning and simulation. This system will be capable of controlling an aircraft during the flight test by performing closed-loop guidance functions, range management, and maneuver-quality monitoring. The rapid-prototyping flight research facility is being developed at the Dryden Flight Research Facility of the NASA Ames Research Center (Ames-Dryden) to provide early flight assessment of emerging AI technology. The facility is being developed as one element of the aircraft automation program which focuses on the qualification and validation of embedded real-time AI-based systems
Oral cancer cells may rewire alternative metabolic pathways to survive from siRNA silencing of metabolic enzymes.
BackgroundCancer cells may undergo metabolic adaptations that support their growth as well as drug resistance properties. The purpose of this study is to test if oral cancer cells can overcome the metabolic defects introduced by using small interfering RNA (siRNA) to knock down their expression of important metabolic enzymes.MethodsUM1 and UM2 oral cancer cells were transfected with siRNA to transketolase (TKT) or siRNA to adenylate kinase (AK2), and Western blotting was used to confirm the knockdown. Cellular uptake of glucose and glutamine and production of lactate were compared between the cancer cells with either TKT or AK2 knockdown and those transfected with control siRNA. Statistical analysis was performed with student T-test.ResultsDespite the defect in the pentose phosphate pathway caused by siRNA knockdown of TKT, the survived UM1 or UM2 cells utilized more glucose and glutamine and secreted a significantly higher amount of lactate than the cells transferred with control siRNA. We also demonstrated that siRNA knockdown of AK2 constrained the proliferation of UM1 and UM2 cells but similarly led to an increased uptake of glucose/glutamine and production of lactate by the UM1 or UM2 cells survived from siRNA silencing of AK2.ConclusionsOur results indicate that the metabolic defects introduced by siRNA silencing of metabolic enzymes TKT or AK2 may be compensated by alternative feedback metabolic mechanisms, suggesting that cancer cells may overcome single defective pathways through secondary metabolic network adaptations. The highly robust nature of oral cancer cell metabolism implies that a systematic medical approach targeting multiple metabolic pathways may be needed to accomplish the continued improvement of cancer treatment
Recruitment of Blue Crab, \u3ci\u3eCallinectes sapidus,\u3c/i\u3e Postlarvae to the Back-Barrier Lagoons of Virginia\u27s Eastern Shore
Most research on the early life history of the blue crab, Callinectes sapidus, has been conducted in large partially stratified estuaries such as the Chesapeake Bay. In contrast, little is known about the recruitment dynamics or habitat requirements of blue crab postlarvae (megalopae) in shallow well-mixed lagoonal systems that make up a considerable part of the species\u27 range. In Virginia\u27s coastal lagoons, planktonic blue crab megalopae are most abundant at night on flooding tides, and are not abundant during the daytime or on ebbing tides. This appears to enhance retention within the lagoons, despite the short residence time of water in the system.
Seagrasses are largely absent from the lagoons and megalopae use benthic macroalgae as a settlement habitat. Laboratory experiments demonstrate that macroalgae is an effective refuge from predation for newly settled megalopae. Megalopae appear to recognize waterborne cues in the lagoon that enhance recruitment by initiating premolt and reducing the time spent in the megalopal stage within the lagoons. Intermolt megalopae exposed to lagoon water quickly advance to premolt and molt to the juvenile stage in approximately 2 days. In contrast, intermolt megalopae held in shore waters appear to delay metamorphosis until estuarine cues are recognized.
The results of this study illustrate some of the adaptations that aid blue crab megalopae in the recruitment to coastal habitats. These adaptations include the ability to recognize and distinguish between inshore and offshore waters, the ability to modify swimming behavior in inshore waters to effect landward transport, and the ability to utilize alternative settlement substrates in the absence of seagrasses
Urine THC Metabolite Levels Correlate with Striatal D2/D3 Receptor Availability
poster abstractRationale: Although the incidence of cannabis abuse/dependence in Americans is rising, the neurobiology of cannabis addiction is not well understood. Recent imaging studies have demonstrated deficits in striatal D2/D3 receptor availability in several substance-dependent populations. However, this has not been studied in chronic cannabis users.
Objective: The purpose of this study was to compare striatal D2/D3 receptor availability between currently using chronic cannabis users and healthy controls.
Methods: Eighteen right-handed males, age 18-35 were studied. Ten subjects were chronic cannabis users; eight were demographically matched controls. Subject eligibility was determined during a screening interview, which included SCID-I and SCID-II assessments, self-report of past substance use, and drug toxicology screening. Subjects underwent a [11C]raclopride (RAC) PET scan; striatal RAC binding potential (BPND) was calculated on a voxel-wise basis with the multilinear reference tissue method. Prior to scanning, urine samples were obtained from cannabis users for quantification of urine Δ-9-tetrahydrocannabinol (THC) and THC metabolites (11-nor-Δ-9-THC-9-carboxylic acid; THC-COOH). Statistical analyses were conducted at voxel-wise level within the striatum. Two-sample t-tests were used to test for differences in BPND between groups. For cannabis subjects, multiple regression analyses were used to test for correlations between striatal BPND and urine THC/THC metabolite levels.
Results: There were no differences in BPND between cannabis smokers and healthy controls. Smokers – regardless of substance – had 10% lower D2/D3 availability than non-smokers. Voxel-wise analyses revealed that striatal RAC BPND values were associated with urine levels of cannabis metabolites.
Conclusions: Cannabis and cannabis metabolites in urine, markers of recent cannabis consumption, are negatively correlated with striatal RAC BPND. This provides the first evidence that degree of cannabis use is related to changes in the central DA system. Low BPND in both cannabis and cigarette users may indicate a deficiency in D2/D3 receptors as a function of chronic exposure to either or both substances. Alternatively, endogenous dopamine levels may be higher in smokers as a result of MAO inhibition from beta-carbolines in the inhaled smoke. Additional studies are needed to understand the complex relationships between chronic cannabis use and the dopamine system
Accuracy and repeatability of wrist joint angles in boxing using an electromagnetic tracking system
© 2019, The Author(s). The hand-wrist region is reported as the most common injury site in boxing. Boxers are at risk due to the amount of wrist motions when impacting training equipment or their opponents, yet we know relatively little about these motions. This paper describes a new method for quantifying wrist motion in boxing using an electromagnetic tracking system. Surrogate testing procedure utilising a polyamide hand and forearm shape, and in vivo testing procedure utilising 29 elite boxers, were used to assess the accuracy and repeatability of the system. 2D kinematic analysis was used to calculate wrist angles using photogrammetry, whilst the data from the electromagnetic tracking system was processed with visual 3D software. The electromagnetic tracking system agreed with the video-based system (paired t tests) in both the surrogate ( 0.9). In the punch testing, for both repeated jab and hook shots, the electromagnetic tracking system showed good reliability (ICCs > 0.8) and substantial reliability (ICCs > 0.6) for flexion–extension and radial-ulnar deviation angles, respectively. The results indicate that wrist kinematics during punching activities can be measured using an electromagnetic tracking system
Time to Metamorphosis of Blue Crab Callinectes Sapidus Megalopae: Effects of Benthic Macroalgae
There is growing evidence that postlarvae (megalopae) of the blue crab Callinectes sapidus can slow the progression through the molt cycle while in offshore nursery grounds, and delay metamorphosis until reinvasion of coastal habitat occurs. However, the cues that trigger metamorphosis of megalopae are not well known. This study tested the hypothesis that the time to metamorphosis (TTM) from the postlarval megalops stage to the first crab stage is shortened in the presence of 2 potential macroalgal settlement substrates, Ulva lactuca (Chlorophyta), and Gracilaria spp. (Rhodophyta). Megalopae and test water were collected from 3 locations (offshore, at a coastal inlet, and inside a coastal lagoon) and tested in a completely crossed factorial experiment with algal type and location as main effects. TTM was longest in offshore treatments (mean TTM 4.72 d) and similar in the inshore treatments (mean inlet TTM 2.73 d, lagoon TTM 2.51 d). TTM of offshore megalopae was reduced in the presence of Ulva lactuca, but macroalgae had little effect on the inshore treatment groups. The effect of algal cues may be masked once megalopae have initiated premolt prior to invading coastal lagoons
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