762 research outputs found
Tectonic overview of the West Gondwana margin
The oceanic southern margin of Gondwana, from southern South America through South Africa, West Antarctica, New Zealand (in its pre break-up position), and Victoria Land to Eastern Australia is one of the longest and longest-lived active continental margins known. It was the site of the 18,000 km Terra Australis orogen, which was initiated in Neoproterozoic times with the break-up of Rodinia, and evolved into the Mesozoic Australides. The Gondwana margin was completed, in Late Cambrian times, by closure of the Adamastor Ocean (between Brazilian and southwest African components) and the Mozambique Ocean (between East and West Gondwana), forming the Brasiliano-Pan-African mobile belts. During the Early Palaeozoic much of the southern margin was dominated by successive episodes of subduction-accretion. Eastern Australia, Northern Victoria Land and the Transantarctic Mountains were affected by one of the first of these events â the Late Cambrian Ross/Delamerian orogeny, remnants of which may be found in the Antarctic Peninsula â but also contain two accreted terranes of unknown age and origin. Similar events are recognized at the South American end of the margin, where the Cambrian Pampean orogeny occurred with dextral strike-slip along the western edge of the RĂo de la Plata craton, followed by an Ordovician active margin (Famatinian) associated with the collision of the Precordillera terrane. However, the central part of the margin (the Sierra de la Ventana of eastern Argentina, the Cape Fold Belt of South Africa and the Ellsworth Mountains of West Antarctica) seem to represent a passive margin during the Early Palaeozoic, with the accumulation of predominantly reworked continental sedimentary deposits (Du Toit's âSamfrau Geosynclineâ). In many of the outer areas, accretion and intense granitic/rhyolitic magmatism continued during the Late Palaeozoic, with collision of several small continental terranes, many of which are nevertheless of Gondwana origin: e.g., southern Patagonia and (possibly) âChileniaâ in the South AmericanâSouth African sectors, and the Western Province and Median Batholith terranes of New Zealand. The rhyolitic PermoâTriassic LIP of southern South America represents a Permo-Triassic switch to extensional tectonics, which continued into the Early Jurassic, and was followed by the establishment of the Andean subduction margin. Elsewhere at this time the margin largely became passive, with terrane accretion continuing in New Zealand. In the Mesozoic, the Terra Australis Orogen evolved into the accretionary Australides, with episodic orogenesis in the New Zealand, West Antarctic and South American sectors in Late TriassicâEarly Jurassic and mid-Cretaceous times, even as Gondwana was breaking up
A search for OH 6 GHz maser emission towards southern supernova remnants
OH masers at 1720 MHz have proven to be excellent indicators of interactions
between supernova remnants and molecular clouds. Recent calculations suggest
that the 6049 MHz OH maser line is excited for higher column densities than for
the 1720 MHz line. It is therefore a potentially valuable indicator of
remnant-cloud interaction.
We present preliminary results of a survey using the Parkes Methanol
Multibeam receiver for 6049 MHz and 6035/6030 MHz OH masers towards 36
supernova remnants and 4 fields in the Large and Small Magellanic Clouds. While
no 6049 MHz masers have been found, three new sites of 6035 and 6030 MHz OH
maser emission have been discovered in star-forming regions.Comment: 2 pages, 1 fig, iaus.cls. To appear in IAU 242, Astrophysical Masers
and Their Environments, eds. J. Chapman & W. Baa
Identification of the Potential High School Dropout
This research was conducted to determine a methodology for the early identification of potential dropouts in the Chesapeake Public School System. A review of research literature determined that many discriminating characteristics had been identified as influential in a student\u27s decision to drop out or stay in school. This study sought to be useful in a practical school setting. Therefore, the study limited its scope to those discriminating characteristics available in student records and thus readily accessible to school personnel. The predictor variables listed below are well documented in the research as discriminating characteristics relating to a student dropping out of school. Data was collected on the following characteristics that were available in the student records of the Chesapeake Public School System to be utilized as predictor variables: (1) absences; (2) achievement test scores--Reading; (3) achievement test scores--English; (4) achievement test scores--Mathematics; (5) achievement test scores--composite; (6) father\u27s education; (7) father\u27s occupation; (8) grade point average; (9) mother\u27s education; (10) mother\u27s occupation; (11) parent\u27s marital status; (12) race; (13) retentions; (14) school attended; (15) sex; (16) transfers. In addition, the student\u27s status during the period of study (dropout or nondropout) was available.
A random sample was selected from the 1988-1989 Chesapeake Public School rolls and a number of analyses, primarily discriminant analysis, were conducted. The analyses were replicated with a fresh sample from 1989-1990 school rolls.
The findings of the analyses indicated that potential school dropouts could be identified in the Chesapeake Public School System with between 90 percent and 98 percent accuracy, depending on the methodology employed. The major predictor variables that consistently emerged as most predictive were absences, retentions, transfers, and mother\u27s education. In addition, schools serving populations more urban in nature exhibited higher dropout rates, and the number of absences proved more predictive in those schools.
The study recommends that this methodology be employed in the school system and results monitored longitudinally to determine if the accuracy of the classification of potential dropouts remains consistent over time. Furthermore, the study recommends that appropriate interventions be developed and monitored to maximize the benefits derived from the early identification of potential dropouts
Software for Training Anomalous Cognition: A Premliminary Report
The role of intuition in fields as widely divergent as science, business, and the arts has a long anecdotal history. Research into the potential for training this area of human performance, however, is not extensive. This report gives the background of anomalous cognition (AC) training devices, and describes a preliminary study involving a software program designed to enhance successful decision-making by training AC of the future and consciousness interaction with electronic systems (CIES). It was hypothesized that motivated subjects would be able to enhance their awareness of subtle internal signals or "intuitive hunches," as shown by increases in scoring. Pilot experiments by 23 experimenter/subjects yielded four who achieved significant gains in scoring at the .01 level, one who achieved both a significant increase and significant overall scoring, and two who showed significant overall scoring. Of 21 subjects who did one AC experiment, a significant percentage (71 %) showed improvement. Eight of the subjects did 25 additional AC experiments, for a total of 46 AC experiments, which together showed a significant increase in scoring, with overall chance scoring. Three subjects, including two new ones, did six CIES experiments, whose combined data showed overall significant scoring. Of 11 dropout subjects, one attained a significant increase in AC scoring. Of the total of 34 subjects, a significant number (six) achieved significant rises in scoring
Integrating AR Technology Into CBM Laboratory Experiments
This paper examines the pilot phase integration of Augmented Reality (AR) technology into a Condition Based Monitoring (CBM) engineering taught module. Students participate in a laboratory cycle within the CBM module, engaging in multiple experiments on a weekly basis, including Shaft Alignment, which provides meaningful, industry-relevant experience in an engineering environment. During the laboratory sessions, multiple pairs of students complete the experiment simultaneously on multiple custom engineering rigs. The Shaft Alignment procedure, although very relevant to industry needs, is also complex and time consuming, with students often struggling to complete the task within the designated laboratory time. AR technology has been introduced into this module to improve the experimental instructional design, improve the learning experiences for the students and reduce unavoidable practical delays during the experimental cycle. Existing experimental procedures have been implemented as AR content including re-crafted instructional content, multimedia content (videos and images), and custom CAD data overlaid on the engineering rigs as AR reference geometry. The newly-introduced AR-based experiments were completed by multiple students over the course of a number of weeks in April and May 2023. Students provided participant feedback via survey before and after engagement with the AR technology. Test groups were aligned within the class as comparators in terms of using existing non-AR procedures and new AR-enhanced procedures. The outcomes from this pilot phase are presented in this paper, with particular focus on student and lecturer experience, knowledge gained in the context of content creation pathways for future AR integration and increased productivity within the laboratory
A search for OH 6 GHz maser emission towards supernova remnants
OH masers at 1720 MHz have proven to be excellent indicators of interactions
between supernova remnants and molecular clouds. OH excitation calculations
suggest that the 6049 MHz OH maser line is excited for higher column densities
than for the 1720 MHz line. Previous observations and modelling of 1612, 1665
and 1667 MHz OH absorption and 1720 MHz OH masers indicated that the column
densities in some supernova remnants, ~1e17 cm^-2, may be high enough for 6049
MHz OH masers to exist. It is therefore a potentially valuable indicator of
remnant-cloud interaction.
We present excitation calculations predicting the formation of 6049 MHz OH
masers and results of a survey using the Parkes Methanol Multibeam receiver for
6049, 6035 and 6030 MHz OH masers towards 35 supernova remnants, a star-forming
region and 4 fields in the Large and Small Magellanic Clouds.
Two new sites of 6035 and 6030 MHz OH maser emission associated with
star-forming regions have been discovered, but no 6049 MHz masers were detected
to a brightness temperature limit of ~0.3-0.6 K, even though modelling of the
OH excitation suggests that maser emission should have been detected. Our
upper-limits indicate that the OH column density for a typical remnant is less
than 1e16.4 cm^-2, which conflicts with observed and modelled column densities.
One possible explanation is that 6049 MHz OH masers may be more sensitive to
velocity coherence than 1720 MHz OH masers under some conditions.Comment: 11 pages, 5 figures, mn2e.cls. Submitted to MNRAS Apr 2008. Accepted
for publication in MNRAS 2008 July 15. Minor changes in the accepted version.
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Dual use of VA and Non-VA Hospitals by Veterans with Multiple Hospitalizations
Background: Veterans who are hospitalized in both VA and non-VA hospitals within a short timespan may be at risk for fragmented or conflicting care. To determine the characteristics of these âdual users,â we analyzed administrative hospital discharge data for VA-enrolled veterans of any age in seven states, including any VA or non-VA hospitalizations they had in 2004 â 2007. Method: For VA enrollees in Arizona, Iowa, Louisiana, Florida, South Carolina, Pennsylvania, or New York in 2007, we merged 2004 â 2007 discharge data for all VA hospitalizations and all non-VA hospitalizations listed in state health department or hospital association databases. For patients hospitalized in 2007, we compared those younger or older than 65 years who had one or multiple hospitalizations during the year, split into users of VA hospitals, non-VA hospitals, or both (â dual users â), on demographics, priority for VA care, travel times, principal diagnoses, co-morbidities, lengths of stay, and prior (2004 â 2006) hospitalizations, using chi-square analysis or ANOVA. Multiply hospitalized patients were compared with multinomial logistic regressions to predict non-VA and dual use. Payers for non-VA hospitalizations also were compared across groups. Results: Of unique inpatients in 2007, 38% of those 65 or older were hospitalized more than once during the year, as were 32% of younger patients; 3 and 8%, respectively, were dual users. Dual users averaged the most index-year (3.7) and prior (1.5) hospitalizations, split evenly between VA and non-VA. They also had higher rates of admission for circulatory diseases, symptoms/signs/ill-defined conditions, and injury and poisoning, and more admissions for multiple diagnostic categories; among younger patients they had the highest rate of mental disorders admissions. Higher income, non-rural residence, greater time to VA care, lower VA priority, prior non-VA hospitalization, no prior VA hospitalization, and several medical categories predicted greater non-VA use. Among younger patients, however, mental disorders predicted more dual use but less exclusively non-VA use. Dual usersâ non-VA admissions were more likely than othersâ to be covered by payers other than Medicare or commercial insurance. Conclusions: Younger dual users require more medical and psychiatric treatment, and rely more on government funding sources. Effective care coordination for these inpatients might improve outcomes while reducing taxpayer burden
West Antarctic Rift System in the Antarctic Peninsula
Decades after the recognition of the West Antarctic Rift System, and in spite of its global importance, the location and nature of the plate boundary it formed at are unknown east of the Byrd Subglacial Basin. Alternative constructions of the circuit of South Pacific plate boundaries suggest the presence of either a transcurrent plate boundary or a continuation of the extensional rift system. We identify George VI Sound, a curved depression separating Alexander Island from Palmer Land, as the easternmost basin of a rift system that terminated at a triple junction with the Antarctic Peninsula subduction zone. The history of the triple junction's third, transform, arm suggests extension started around 33.5-30 Ma. A more speculatively identified basin further west may have formed earlier during the same episode of rifting, starting around 43 Ma. Proposals of earlier Cenozoic relative motion between East and West Antarctica cannot be verified from this region. Citation: Eagles, G., R. D. Larter, K. Gohl, and A. P. M. Vaughan (2009), West Antarctic Rift System in the Antarctic Peninsula, Geophys. Res. Lett., 36, L21305, doi: 10.1029/2009GL040721
Evaluating Network Performance of Containerized Test Framework for Distributed Space Systems
Distributed space systems are a mission architecture consisting of multiple spacecraft as a cohesive system which provide multipoint sampling, increased mission coverage, or improved sample resolution, while reducing mission risk through redundancy. To fully realize the potential of these systems, eventually scaling to hundreds or thousands of spacecraft, distributed space systems need to be operated as a single entity, which will enable a variety of novel scientific space missions. The Distributed Spacecraft Autonomy (DSA) project is a software project which aims to mature the technology needed for those systems, namely autonomous decision-making and swarm networking. The DSA project leverages a containerized swarm test framework to simulate spacecraft software, which can identify emergent behavior early in development. Container virtualization allows distributed spacecraft systems to be simulated entirely in software on a single computer, avoiding the overhead associated with conventional approaches like hardware facsimiles and virtual machines. For this approach to be effective, the simulated system behavior must not be artificially influenced by the swarm test framework itself. To address this, we present a series of benchmarks to quantify virtual network bandwidth available on a single-host computer and contextualize this against the network and application behavior of the DSA swarm test framework
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