924 research outputs found

    Distributed science operations for JPL planetary missions

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    Advances in spacecraft, flight instruments, and ground systems provide an impetus and an opportunity for scientific investigation teams to take direct control of their instruments' operations and data collection while at the same time, providing a cost effective and flexible approach in support of increasingly complex science missions. Operations of science instruments have generally been integrated into planetary flight and ground systems at a very detailed level. That approach has been successful, but the cost of incorporating instrument expertise into the central mission operations system has been high. This paper discusses an approach to simplify planetary science operations by distributing instrument computing and data management tasks from the central mission operations system to each investigator's home center of observational expertise. Some early results of this operations concept will be presented based on the Mars Observer (MO) Project experience and Cassini Project plans

    City of Wind, City of Fire: Education and Activism in Chicago 1966-1975

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    This paper emphasizes the pedagogical contributions that drove the political awareness and action of Black and Brown youth in Chicago from 1966-1975. The critical education of the Communiversity on the Southside and the Chicago Young Lords Organization (ChYLO) on the Northside addressed deficiencies in educational institutions and aided urban youth in combating the post-industrial, socio-political, and economic challenges of Chicago communities. Through a critical analysis of interview and archival data of ChYLO and Communiversity, we highlight their significant contributions to the field of education. In this article, we frame these formations as the work of critical pedagogy. Our analysis of these youth/student organizations uncovers frameworks that contribute to the work of educators and youth via: 1) examination of educational topics rooted in community concerns, 2) the study of texts that promote critical understandings and analysis of unjust structures and systems at local, national and global levels, and 3) pedagogical practices that account and adjust for the living and learning conditions of poor Black and Brown communities

    Study of three-dimensional nonlinear nip mechanics

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    An understanding of nip pressure and deformed nip geometry is of vital importance to the design of web handling equipment. Axial variations in nip pressure and deformed nip geometry can lead to poor product performance and customer dissatisfaction. This study evaluates these axial variations for two general cases: an identical-hollow-drum design and a classic calendaring design. Both cases include the effects of elastomeric coverings. Comparisons between modelling the resulting axial variations in nip parameters by beam effects or shell effects are evaluated. Evaluations of nip pressure and overdrive/underdrive are performed. Approximate boundary conditions for the study of web wrinkling are proposed based on deformed nip geometry

    A temperate palaeodiversity peak in Mesozoic dinosaurs and evidence for Late Cretaceous geographical partitioning

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    Aim  Modern biodiversity peaks in the tropics and declines poleward, a pattern that is potentially driven by climate. Although this latitudinal biodiversity gradient (LBG) also characterizes the marine invertebrate fossil record, distributions of ancient terrestrial faunas are poorly understood. This study utilizes data on the dinosaur fossil record to examine spatial patterns in terrestrial biodiversity throughout the Mesozoic.\ud Location  We compiled data on fossil occurrences across the globe.\ud Methods  We compiled a comprehensive dataset of Mesozoic dinosaur genera (738), including birds. Following the utilization of sampling standardization techniques to mediate for the uneven sampling of the fossil record, we constructed latitudinal patterns of biodiversity from this dataset.\ud Results  The dominant group of Mesozoic terrestrial vertebrates did not conform to the modern LBG. Instead, dinosaur diversity was highest at temperate palaeolatitudes throughout the 160 million year span of dinosaurian evolutionary history. Latitudinal diversity correlates strongly with the distribution of land area. Late Cretaceous sauropods and ornithischians exhibit disparate LBGs.\ud Main conclusions  The continuity of the palaeotemperate peak in dinosaur diversity indicates a diminished role for climate on the Mesozoic LBG; instead, dinosaur diversity may have been driven by the amount of land area among latitudinal belts. There is no evidence that the tropics acted as a cradle for dinosaur diversity. Geographical partitioning among major clades of herbivorous dinosaurs in the Late Cretaceous may result from the advanced stages of continental fragmentation and/or differing responses to increasing latitudinal climatic zonation. Our results suggest that the modern-day LBG on land was only established 30 million years ago, following a significant post-Eocene recalibration, potentially related to increased seasonality

    Overcoming the fear: an autoethnographic narrative of running with epilepsy

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    Through a phenomenological approach, this article explores the identity conflict that arose within a female runner after diagnosis with epilepsy. Utilising a three month autoethnography to track her experiences of returning to running, the first author narrates the effect of epilepsy on her identity formation. Providing a voice that is absent from a research area dominated by statistics, the reader is asked to involve him/herself in the world of this athlete and in turn embrace the use of narratives as a valuable coping mechanism for those with chronic disorders

    Presence of mechanical dyssynchrony in duchenne muscular dystrophy

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    <p>Abstract</p> <p>Background</p> <p>Cardiac dysfunction in boys with Duchenne muscular dystrophy (DMD) is a leading cause of death. Cardiac resynchronization therapy (CRT) has been shown to dramatically decrease mortality in eligible adult population with congestive heart failure. We hypothesized that mechanical dyssynchrony is present in DMD patients and that cardiovascular magnetic resonance (CMR) may predict CRT efficacy.</p> <p>Methods</p> <p>DMD patients (n = 236) were stratified into 4 groups based on age, diagnosis of DMD, left ventricular (LV) ejection fraction (EF), and presence of myocardial fibrosis defined as positive late gadolinum enhancement (LGE) compared to normal controls (n = 77). Dyssynchrony indices were calculated based on timing of CMR derived circumferential strain (e<sub>cc</sub>). The calculated indices included cross-correlation delay (XCD), uniformity of strain (US), regional vector of variance (RVV), time to maximum strain (TTMS) and standard deviation (SD) of TTMS. Abnormal XCD value was defined as > normal + 2SD. US, RVV, TTMS and SD were calculated for patients with abnormal XCD.</p> <p>Results</p> <p>There was overall low prevalence of circumferential dyssynchrony in the entire DMD population; it increased to 17.1% for patients with abnormal EF and to 31.2% in the most advanced stage (abnormal EF with fibrosis). All but one DMD patient with mechanical dyssynchrony exhibited normal QRS duration suggesting absence of electrical dyssynchrony. The calculated US and RVV values (0.91 ± 0.09, 1.34 ± 0.48) indicate disperse rather than clustered dyssynchrony.</p> <p>Conclusion</p> <p>Mechanical dyssynchrony is frequent in boys with end stage DMD-associated cardiac dysfunction. It is associated with normal QRS complex as well as extensive lateral fibrosis. Based on these findings, it is unlikely that this patient population will benefit from CRT.</p

    Mass transport by buoyant bubbles in galaxy clusters

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    We investigate the effect of three important processes by which AGN-blown bubbles transport material: drift, wake transport and entrainment. The first of these, drift, occurs because a buoyant bubble pushes aside the adjacent material, giving rise to a net upward displacement of the fluid behind the bubble. For a spherical bubble, the mass of upwardly displaced material is roughly equal to half the mass displaced by the bubble, and should be ~ 10^{7-9} solar masses depending on the local ICM and bubble parameters. We show that in classical cool core clusters, the upward displacement by drift may be a key process in explaining the presence of filaments behind bubbles. A bubble also carries a parcel of material in a region at its rear, known as the wake. The mass of the wake is comparable to the drift mass and increases the average density of the bubble, trapping it closer to the cluster centre and reducing the amount of heating it can do during its ascent. Moreover, material dropping out of the wake will also contribute to the trailing filaments. Mass transport by the bubble wake can effectively prevent the build-up of cool material in the central galaxy, even if AGN heating does not balance ICM cooling. Finally, we consider entrainment, the process by which ambient material is incorporated into the bubble. AbridgedComment: Accepted for publication in MNRAS. 17 pages, 4 figures, 2 tables. Formatted for letter paper and adjusted author affiliations
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