4,537 research outputs found
Herschel evidence for disk flattening or gas depletion in transitional disks
Transitional disks are protoplanetary disks characterized by reduced near-
and mid-infrared emission with respect to full disks. This characteristic
spectral energy distribution indicates the presence of an optically thin inner
cavity within the dust disk believed to mark the disappearance of the
primordial massive disk. We present new Herschel Space Observatory PACS spectra
of [OI] 63 micron for 21 transitional disks. Our survey complements the larger
Herschel GASPS program "Gas in Protoplanetary Systems" (Dent et al. 2013) by
quadrupling the number of transitional disks observed with PACS at this
wavelength. [OI] 63 micron traces material in the outer regions of the disk,
beyond the inner cavity of most transitional disks. We find that transitional
disks have [OI] 63 micron line luminosities two times fainter than their full
disk counterparts. We self consistently determine various stellar properties
(e.g. bolometric luminosity, FUV excess, etc.) and disk properties (e.g. disk
dust mass, etc.) that could influence the [OI] 63 micron line luminosity and we
find no correlations that can explain the lower [OI] 63 micron line
luminosities in transitional disks. Using a grid of thermo-chemical
protoplanetary disk models, we conclude that either transitional disks are less
flared than full disks or they possess lower gas-to-dust ratios due to a
depletion of gas mass. This result suggests that transitional disks are more
evolved than their full disk counterparts, possibly even at large radii.Comment: Accepted for publication in ApJ; 52 pages, 16 figures, 8 table
Effects of Supplementary Concentrate Level and Separate or Mixed Feeding of Grass Silage and Concentrates on Rumen Fluid Composition in Steers
The effects of dietary concentrate level and method of feeding (separate or mixed) on performance and carcass traits of steers may be mediated through changes in rumen fluid composition. The objectives of this study were to determine the effects on rumen fluid composition of (1) supplementary concentrate level with grass silage, and (2) separate or mixed feeding of silage and concentrates
Effects of Supplementary Concentrate Level and Separate or Mixed Feeding of Grass Silage and Concentrates on Carcass Tissue Composition in Steers
Supplementary concentrate level may affect carcass composition in steers. Feeder wagons facilitate feeding and management. The objectives were to determine the effects of (1) supplementary concentrate level with grass silage, and (2) separate or mixed feeding of silage and concentrates, on ribs joint composition
A Census of Rotating Radio Transients at 150 MHz with the Irish LOFAR Station
Rotating radio transients (RRATs) are neutron stars that emit detectable
radio bursts sporadically. They are statistically distinct in the neutron star
population, in many observable properties, but by their nature are practically
difficult to study in depth. In this paper, we present the results from 1408 h
of observations of RRAT candidates using the Irish station of the Low Frequency
Array (LOFAR) at 150 MHz. As of October 2022, this census involved observing
113 sources, leading to 29 detections which were then followed up
systematically. Single-pulse emission was detected from 25 sources, and
periodic emission from 14 sources. 18 sources were found to have emission
behaviour that is not discussed in prior works using LOFAR instruments. Four
novel or modified source periods have been determined, ranging from 1.5-3.9 s,
and 8 new or updated phase-coherent pulsar timing ephemerides have been
produced using detected bursts. One unexpected single-pulse with a
clearly-Galactic dispersion measure was detected as a part of this work, but
has not been re-detected in follow-up observations. Observations are ongoing to
expand the number of observed sources and further characterise and improve
ephemerides for the detected sources. This census has demonstrated the
capability for international LOFAR stations to detect, monitor and characterise
a significant fraction of these unique sources.Comment: Accepted by MNRAS. 24 pages, 7 figures, 8 table
French responses to the Prague Spring: connections, (mis)perception and appropriation
Looking at the vast literature on the events of 1968 in various European countries, it is striking that the histories of '1968' of the Western and Eastern halves of the continent are largely still written separately.1 Nevertheless, despite the very different political and socio-economic contexts, the protest movements on both sides of the Iron Curtain shared a number of characteristics. The 1968 events in Czechoslovakia and Western Europe were, reduced to the basics, investigations into the possibility of marrying social justice with liberty, and thus reflected a tension within European Marxism. This essay provides an analysis specifically of the responses by the French left—the Communist Party, the student movements and the gauchistes—to the Prague Spring, characterised by misunderstandings and strategic appropriation. The Prague Spring was seen by both the reformist and the radical left in France as a moderate movement. This limited interpretation of the Prague Spring as a liberal democratic project continues to inform our memory of it
Effects of Supplementary Concentrate Level and Separate or Mixed Feeding of Grass Silage and Concentrates on Carcass Tissue Colour Traits in Steers
The level of supplementary concentrates fed with grass silage and the method of feeding (separate or mixed) may affect carcass tissue colour in steers. The objectives were to determine the effects of (1) supplementary concentrate level with grass silage, and (2) separate or mixed feeding of silage and concentrates, on muscle and fat colour
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