140 research outputs found
Refined Gearbox Design for the Chariot Lunar Rover
In planning for NASA's return to the moon by the year 2020, the NASA Johnson Space Center (JSC) designed and built a lunar concept vehicle called Chariot. Slightly larger than a pickup truck, it was designed to demonstrate similar utilitarian functions, but with twelve wheels for redundancy, reliability, and reduced surface contact pressure. JSC designed a motor gearbox to drive each of Chariot s six wheel pods. The pods can be independently steered over 360 for maneuverability. This paper describes the design of a second generation, drop-in replacement gearbox. The new design has a lower parts count, and is lighter than the original, which represents a step toward flight hardware
Multivariate variance-components analysis of longitudinal blood pressure measurements from the Framingham Heart Study
Multivariate variance-components analysis provides several advantages over univariate analysis when studying correlated traits. It can test for pleiotropy or (in the longitudinal context) gene × age interaction. It can also have more power than univariate analyses to detect a quantitative trait locus influencing several traits. We apply multivariate variance components to longitudinal systolic blood pressure data from the Framingham Heart Study. We find evidence for a polygenic influence on blood pressure (heritabilities at different ages range from 27% to 38%). Tests based on a factor-analytic parameterization of the polygenic variance find significant (p < 2 × 10(-3)) evidence that different genes affect blood pressure at different ages. Still, estimates for the proportion of polygenic variance due to shared genes ran as high as 85% for some trait pairs. Univariate and multivariate linkage analyses replicate previous linkage results on chromosome 17 (maximum LOD scores of 2.2 and 2.4, respectively). In this study, multivariate analysis provides no increase in power; this is likely due to the strong positive correlation in systolic blood pressure measured at different ages
A Basic Robotic Excavator (the Glenn Digger): Description, Design, and Initial Operation
This paper describes the design, commercial part selections, fabrication, assembly, installation, and initial operation of a two degree of freedom robotic excavator. Colloquially referred to as "the NASA Glenn Digger," it was designed specifically to be mounted onto, and to operate with, the then newly developed Centaur 2 robotic mobility base. The excavator, when mounted to Centaur 2, is designed to scoop loose regolith from the terrain, raise its loaded bucket up and dump the load into a hopper of at least a 1-m-height. The hopper represents the input to a machine that would process the raw material, such as to produce oxygen from lunar regolith as would be required for long-term lunar habitation. This equipment debuted at the annual Research and Technology Studies ("Desert RATS", Ref. 1) event held north of Flagstaff, Arizona, in September of 2010, when the Digger was successfully joined to Centaur 2 and the shoveling articulation was demonstrated. During 2011, the hardware was modified for added strength, strain gauges were added to measure loads, and the controls were improved in preparation for the 2011 Desert RATS event, where additional "field operations" experience was gained
Can local ecological knowledge establish conservation baselines for the Critically Endangered Blue-crowned Laughingthrush?
Designing conservation interventions for rare species can be hindered by a lack of relevant data. Local ecological knowledge (LEK) has potential to provide rapidly collected, cost‐effective data across large spatio‐temporal scales, but has rarely been used as a source of conservation‐relevant information for the Asian Songbird Crisis. The Blue‐crowned Laughingthrush (Pterorhinus courtoisi; BCLT) is a Critically Endangered passerine found only in southeastern China. It is unclear why the species' breeding range and global population are extremely small, as it occurs in human‐occupied forest‐agricultural landscapes similar to surrounding environments across southern China. We conducted systematic range‐wide interviews on BCLT (n = 519) to collect novel information on the species' temporal and spatial distribution, and on potential human activities and landscape changes associated with its presence or absence. Recognition of BCLT was moderate (45.0% of respondents reported sightings), with sightings within the previous 18 months across the study area, within and beyond their known distribution. Over half of known breeding villages were confirmed by LEK data, and nesting was reported from two villages with no previous breeding records. BCLT trapping was reported across the study landscape, mostly from the last decade and associated with trappers from urban centres. BCLT trapping and lack of fengshui forest were associated with sites where BCLTs did not breed. Breeding sites were associated with increases in vegetable gardens over respondents' lifetimes, and other sites within the species' range were associated with decreases in bush/scrub. We demonstrate that LEK can identify potential threats, new breeding sites and landscape changes correlated with species presence or absence for threatened birds affected by the Asian songbird crisis. This study provides the first evidence of ongoing trapping as a threat to BCLT, and remedial measures are urgently required across the region. Read the free Plain Language Summary for this article on the Journal blog
Extraction and Capture of Water from Martian Regolith Experimental Proof-of-Concept
Mars Design Reference Architecture 5.0:Lists in-situ resource utilization (ISRU) as enabling for robust human Mars missionsLO2LCH4 ascent propulsion 25,000 kg oxygen from atmosphere for ascent and life support Atmospheric based ISRU processes less operationally complex than surface based limited concept evaluation to date and Mars surface water property and distribution uncertainty would not allow [Mars soil water processing] to be base lined at this time Limited Concept Evaluation to Date Lunar regolith O2 extraction processing experience Lunar regolith is fluidized and heated to high temperatures with H2 to produce H2O from iron-bearing minerals Mars similarity concept: Soil placed in fluidized bed reactor Heated to moderate temperatures Inert gas flow used to fluidize the bed and help with water desorption Challenges: High-temperature dusty seals Working gas requires downstream separation and recycling to reduce consumables loss Batch process heating thermally inefficient
Anti-Nirvana: crime, culture and instrumentalism in the age of insecurity
‘Anti-Nirvana’ explores the relationship between consumer culture, media and criminal motivations. It has appeared consistently on the list of the top-ten most-read articles in this award-winning international journal, and it mounts a serious neo-Freudian challenge to the predominant naturalistic notion of ‘resistance’ at the heart of liberal criminology and media studies. It is also cited in the Oxford Handbook of Criminology and other criminology texts as a persuasive argument in support of the theory that criminality amongst young people is strongly linked to the acquisitive values of consumerism and the images of possessive individualism that dominate mass media
Living for the weekend: youth identities in northeast England
Consumption and consumerism are now accepted as key contexts for the construction of youth identities in de-industrialized Britain. This article uses empirical evidence from interviews with young people to suggest that claims of `new community' are overstated, traditional forms of friendship are receding, and increasingly atomized and instrumental youth identities are now being culturally constituted and reproduced by the pressures and anxieties created by enforced adaptation to consumer capitalism. Analysis of the data opens up the possibility of a critical rather than a celebratory exploration of the wider theoretical implications of this process
A tale of two capitalisms: preliminary spatial and historical comparisons of homicide rates in Western Europe and the USA
This article examines comparative homicide rates in the United States and Western Europe in an era of increasingly globalized neoliberal economics. The main finding of this preliminary analysis is that historical and spatial correlations between distinct forms of political economy and homicide rates are consistent enough to suggest that social democratic regimes are more successful at fostering the socio-cultural conditions necessary for reduced homicide rates. Thus Western Europe and all continents and nations should approach the importation of American neo-liberal economic policies with extreme caution. The article concludes by suggesting that the indirect but crucial causal connection between political economy and homicide rates, prematurely pushed into the background of criminological thought during the ‘cultural turn’, should be returned to the foreground
Sound Studies Meets Deaf Studies
Sound studies and Deaf studies may seem at first impression to operate in worlds apart. We argue in this article, however, that similar renderings of hearing, deafness, and seeing as ideal types - and as often essentialized sensory modes - make it possible to read differences between Sound studies and Deaf studies as sites of possible articulation. We direct attention to four zones of productive overlap, attending to how sound is inferred in deaf and Deaf practice, how reimagining sound in the register of low-frequency vibration can upend deafhearing dichotomies, how “deaf futurists“ champion cyborg sound, and how signing and other non-spoken communicative practices might undo phonocentric models of speech. Sound studies and Deaf studies emerge as fields with much to offer one another epistemologically, theoretically, and practically
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