3,423 research outputs found

    SOUSA: the Swift Optical/Ultraviolet Supernova Archive

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    The Ultra-Violet Optical Telescope on the Swift spacecraft has observed hundreds of supernovae, covering all major types and most subtypes. Here we introduce the Swift Optical/Ultraviolet Supernova Archive (SOUSA), which will contain all of the supernova images and photometry. We describe the observation and reduction procedures and how they impact the final data. We show photometry from well-observed examples of most supernova classes, whose absolute magnitudes and colors may be used to infer supernova types in the absence of a spectrum. A full understanding of the variety within classes and a robust photometric separation of the groups requires a larger sample, which will be provided by the final archive. The data from the existing Swift supernovae are also useful for planning future observations with Swift as well as future UV observatories.Comment: Accepted for publication in the UV issue of Astrophysics and Space Science 10 pages, 6 figures SOUSA is an archive in progress with data being posted to the Swift SN website: http://swift.gsfc.nasa.gov/docs/swift/sne/swift_sn.htm

    COLOR DEPENDENCE IN THE SIZE DISTRIBUTION OF MAIN BELT ASTEROIDS REVISITED

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    ABSTRACT The size distribution of the asteroid belt is examined with 16956 main belt asteroids detected in data taken from the Canada-France-Hawaii Telescope Legacy Survey in two filters (g and r ). The cumulative H (absolute magnitude) distribution is examined in both filters, and both match well to simple power laws down to H = 17, with slopes in rough agreement with those reported the literature. This implies that disruptive collisions between asteroids are gravitationally dominated down to at least this size, and probably sub-kilometer scales. The slopes of these distributions appear shallower in the outer belt than the inner belt, and the g distributions appear slightly steeper than the r . The slope shallowing in the outer belt may reflect a real compositional difference: the inner asteroid belt has been suggested to consist mostly of stony and/or metallic S-type asteroids, whereas carbonaceous C-types are thought to be more prevalent further from the Sun. No waves are seen in the size distribution above H = 15. Since waves are expected to be produced at the transition from gravitationally-dominated to internal strength-dominated collisions, their absence here may imply that the transition occurs at sub-kilometer scales, much smaller than the H = 17 (diameter āˆ¼ 1.6 km) cutoff of this study

    A Tree-Ring Record of Historical Fire Activity In a Piedmont Longleaf Pine (\u3ci\u3ePinus palustris\u3c/i\u3e Mill.) Woodland In North Carolina, USA

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    CO2 capture from industrial point source waste streams represents an important need for achieving the global goal of carbon-neutrality. Compared with conventional liquid sorbents, solid sorbents can exhibit several distinct advantages, including enhanced lifetime and reduced energy consumption for sorbent regeneration. Considering that reducing CO2 emission is a great challenge, reaching approximately 37 billion metric tons just in 2021, ideal sorbent solutions should not only exhibit a high capture performance but also enable large scale manufacturing using low-cost precursors and simple processes. In this work, we demonstrate the use of a commodity polymer, polystyrene-block-polyisoprene-block-polystyrene (SIS), as the starting material for preparing hierarchically porous, sulfur-doped carbons for CO2 capture. Particularly, the sulfonation-crosslinking reaction enables the formation of macropores in the polymer framework due to the release of gaseous byproducts. After carbonization and activation, the highly porous structure of SIS-derived carbons is successfully retained, while their surface area can reach up to 905 m2 gāˆ’1. These porous carbon sorbents exhibit excellent CO2 uptake performance, reaching sorption capacities of 3.8 mmol gāˆ’1 at 25 Ā°C and 6.0 mmol gāˆ’1 at 0 Ā°C, as well as a high selectivity up to 43ā€†:ā€†1 against N2 gas under ambient conditions. Overall, our work provides an industrially viable method for ā€œtemplate-freeā€ fabrication of porous carbons from commodity polyolefin-based materials, which can be employed for reducing CO2 emission from industrial plants/sectors

    Step Counts of 10- to 11-Year-Old Children by Ethnicity and Metropolitan Status

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    Background: The purpose of this study was to conduct a secondary analysis by combining 2 pedometer data sets to describe and analyze pedometer-determined steps/day of children by ethnicity and metropolitan status. Methods: Participants were 582 children (309 girls, 273 boys; 53% Hispanic, 26% Caucasian, 21% African American) age 10 to 11 years (M = 10.37 Ā± 0.48) attending 1 of 10 schools located in urban, suburban, and rural settings. Participants wore a research grade pedometer for at least 3 week/school days. Mean steps/ day were analyzed by gender, ethnicity, and metropolitan status. Results: Statistical analyses indicated 1) boys (12,853 Ā± 3831; P \u3c .001) obtained significantly more steps/day than girls (10,409 Ā± 3136); 2) African American (10,709 Ā± 3386; P \u3c .05) children accumulated significantly less steps/day than Hispanic (11,845 Ā± 3901) and Caucasian (11,668 Ā± 3369) children; and 3) urban (10,856 Ā± 3706; P \u3c .05) children obtained significantly less steps/day than suburban (12,297 Ā± 3616) and rural (11,934 Ā± 3374) children. Conclusions: Findings support self-report data demonstrating reduced physical activity among African American children and youth, especially girls, and among children and youth living in urban areas. Possible reasons for these discrepancies are explored

    Reorganization of syntactic processing following left-hemisphere brain damage: does right-hemisphere activity preserve function?

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    The extent to which the human brain shows evidence of functional plasticity across the lifespan has been addressed in the context of pathological brain changes and, more recently, of the changes that take place during healthy ageing. Here we examine the potential for plasticity by asking whether a strongly left-lateralized system can successfully reorganize to the right-hemisphere following left-hemisphere brain damage. To do this, we focus on syntax, a key linguistic function considered to be strongly left-lateralized, combining measures of tissue integrity, neural activation and behavioural performance. In a functional neuroimaging study participants heard spoken sentences that differentially loaded on syntactic and semantic information. While healthy controls activated a left-hemisphere network of correlated activity including Brodmann areas 45/47 and posterior middle temporal gyrus during syntactic processing, patients activated Brodmann areas 45/47 bilaterally and right middle temporal gyrus. However, voxel-based morphometry analyses showed that only tissue integrity in left Brodmann areas 45/47 was correlated with activity and performance; poor tissue integrity in left Brodmann area 45 was associated with reduced functional activity and increased syntactic deficits. Activity in the right-hemisphere was not correlated with damage in the left-hemisphere or with performance. Reduced neural integrity in the left-hemisphere through brain damage or healthy ageing results in increased right-hemisphere activation in homologous regions to those left-hemisphere regions typically involved in the young. However, these regions do not support the same linguistic functions as those in the left-hemisphere and only indirectly contribute to preserved syntactic capacity. This establishes the unique role of the left hemisphere in syntax, a core component in human language

    Step Counts of Non-White Minority Children and Youth by Gender, Grade Level, Race/Ethnicity, and Mode of School Transportation

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    Background: The purposes of this study were to describe and analyze the steps/d of nonwhite minority children and youth by gender, grade level, race/ethnicity, and mode of school transportation. A secondary purpose was to compare the steps/d of minority children and youth to their Caucasian grade-level counterparts. Methods: Participants were 547 minority youth grades 5 to 8 from 4 urban schools. Participants wore sealed pedometers for 6 consecutive week/school days. Three hundred and ten participants responded to a questionnaire concerning their mode of transportation to and from school. Results: Statistical analyses indicated a main effect for gender (F(3,546) = 13.50, P \u3c .001) with no interaction. Boys (12,589 Ā± 3921) accumulated significantly more steps/d than girls (9,539 Ā± 3,135). Further analyses also revealed a significant main effect for mode of school transportation (F(2, 309) = 15.97, P \u3c .001). Walkers (12,614 Ā± 4169) obtained significantly more steps/d than car (10,021 Ā± 2856) or bus (10,230 Ā± 3666) transit users. Conclusions: Minority boys obtain similar steps/d as their Caucasian grade-level counterparts; minority girls obtain less steps/d than their Caucasian grade-level counterparts. Minority youth who actively commute are more likely to meet PA recommendations than nonactive commuters

    Preserving syntactic processing across the adult life span: the modulation of the frontotemporal language system in the context of age-related atrophy.

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    Although widespread neural atrophy is an inevitable consequence of normal aging, not all cognitive abilities decline as we age. For example, spoken language comprehension tends to be preserved, despite atrophy in neural regions involved in language function. Here, we combined measures of behavior, functional activation, and gray matter (GM) change in a younger (19-34 years) and older group (49-86 years) of participants to identify the mechanisms leading to preserved language comprehension across the adult life span. We focussed primarily on syntactic functions because these are strongly left lateralized, providing the potential for contralateral recruitment. In an functional magnetic resonance imaging study, we used a word-monitoring task to minimize working memory demands, manipulating the availability of semantics and syntax to ask whether syntax is preserved in aging because of the functional recruitment of other brain regions, which successfully compensate for neural atrophy. Performance in the older group was preserved despite GM loss. This preservation was related to increased activity in right hemisphere frontotemporal regions, which was associated with age-related atrophy in the left hemisphere frontotemporal network activated in the young. We argue that preserved syntactic processing across the life span is due to the shift from a primarily left hemisphere frontotemporal system to a bilateral functional language network
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