1,504 research outputs found
Tomographic filtering of geodynamic models: Implications for model interpretation and largeâscale mantle structure
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94833/1/jgrb15038.pd
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Linguistic Signatures of Cognitive Processes during Writing
The relationship between working memory capacity andwriting ability was examined via a linguistic analysis ofstudent essays. Undergraduate students (n = 108) wrotetimed, prompt-based essays and completed a battery ofcognitive assessments. The surface- and discourse-levellinguistic features of studentsâ essays were then analyzedusing natural language processing tools. The results indicatedthat WM capacity was related to surface-level, but notdiscourse-level features of student essays. Additionally, theresults suggest that these relationships were attenuated forstudents with high inferencing skills, as opposed to those withlower inferencing skill
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Cohesive Features of Deep Text Comprehension Processes
This study investigates how cohesion manifests in readersâthought processes while reading texts when they areinstructed to engage in self-explanation, a strategy associatedwith deeper, more successful comprehension. In Study 1,college students (n = 21) were instructed to either paraphraseor self-explain science texts. Paraphrasing was characterizedby greater cohesion in terms of lexical overlap whereas self-explanation included greater lexical diversity and moreconnectives to specify relations between ideas. In Study 2,adolescent students (n = 84) were provided with instructionand practice in self-explanation and reading strategies across8 sessions. Self-explanations increased in lexical diversity butbecame more causally and semantically cohesive over time.Together, these results suggest that cohesive featuresexpressed in think alouds are indicative of the depth ofstudentsâ comprehension processes
Energy non-equipartition in systems of inelastic, rough spheres
We calculate and verify with simulations the ratio between the average
translational and rotational energies of systems with rough, inelastic
particles, either forced or freely cooling. The ratio shows non-equipartition
of energy. In stationary flows, this ratio depends mainly on the particle
roughness, but in nonstationary flows, such as freely cooling granular media,
it also depends strongly on the normal dissipation. The approach presented here
unifies and simplifies different results obtained by more elaborate kinetic
theories. We observe that the boundary induced energy flux plays an important
role.Comment: 4 pages latex, 4 embedded eps figures, accepted by Phys Rev
A direct limit on the turbulent velocity of the intracluster medium in the core of Abell 1835 from XMM-Newton
We examine deep XMM-Newton Reflection Grating Spectrometer (RGS) observations
of the X-ray luminous galaxy cluster A1835. For the first time in a galaxy
cluster we place direct limits on turbulent broadening of the emission lines.
This is possible because the coolest X-ray emitting gas in the cluster, which
is responsible for the lines, occupies a small region within the core. The most
conservative determination of the 90 per cent upper limit on line-of-sight,
non-thermal, velocity broadening is 274 km/s, measured from the emission lines
originating within 30 kpc radius. The ratio of turbulent to thermal energy
density in the core is therefore less than 13 per cent. There are no emission
lines in the spectrum showing evidence for gas below ~3.5 keV. We examine the
quantity of gas as a function of temperature and place a limit of 140 Msun/yr
(90 per cent) for gas cooling radiatively below 3.85 keV.Comment: 5 pages, accepted by MNRAS, includes minor change suggested by
refere
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Document Cohesion Flow: Striving towards Coherence
Text cohesion is an important element of discourseprocessing. This paper presents a new approach to modeling,quantifying, and visualizing text cohesion using automatedcohesion flow indices that capture semantic links amongparagraphs. Cohesion flow is calculated by applyingCohesion Network Analysis, a combination of semanticdistances, Latent Semantic Analysis, and Latent DirichletAllocation, as well as Social Network Analysis. Experimentsperformed on 315 timed essays indicated that cohesion flowindices are significantly correlated with human ratings of textcoherence and essay quality. Visualizations of the globalcohesion indices are also included to support a more facileunderstanding of how cohesion flow impacts coherence interms of semantic dependencies between paragraphs
Systematic study of X-ray Cavities in the brightest galaxy of the Draco Constellation NGC 6338
We present results based on the systematic analysis of currently available
Chandra archive data on the brightest galaxy in the Draco constellation NGC
6338, in order to investigate the properties of the X-ray cavities. In the
central ~6 kpc, at least a two and possibly three, X-ray cavities are evident.
All these cavities are roughly of ellipsoidal shapes and show a decrement in
the surface brightness of several tens of percent. In addition to these
cavities, a set of X-ray bright filaments are also noticed which are spatially
coincident with the H{\alpha} filaments over an extent of 15 kpc. The H{\alpha}
emission line filaments are perpendicular to the X- ray cavities. Spectroscopic
analysis of the hot gas in the filaments and cavities reveal that the X-ray
filaments are cooler than the gas contained in the cavities. The emission line
ratios and the extended, asymmetric nature of the H{\alpha} emission line
filaments seen in this system require a harder ionizing source than that
produced by star formation and/or young, massive stars. Radio emission maps
derived from the analysis of 1.4 GHz VLA FIRST survey data failed to show any
association of these X-ray cavities with radio jets, however, the cavities are
filled by radio emission. The total power of the cavities is 17\times 1042 erg
s-1 and the ratio of the radio luminosity to cavity power is ~ 10-4, implying
that most of the jet power is mechanical.Comment: The paper contains 12 figures and 3 tables, Accepted 2011 December 7
for publication in MNRA
AGN-Induced Cavities in NGC 1399 and NGC 4649
We present an analysis of archival Chandra and VLA observations of the E0
galaxy NGC 1399 and the E2 galaxy NGC 4649 in which we investigate cavities in
the surrounding X-ray emitting medium caused by the central AGN. We calculate
the jet power required for the AGN to evacuate these cavities and find values
of ~8x10^{41} erg/s and ~14x10^{41} erg/s for the lobes of NGC 1399 and
~7x10^{41} erg/s and ~6x10^{41} erg/s for those of NGC 4649. We also calculate
the k/f values for each cavity, where k is the ratio of the total particle
energy to that of electrons radiating in the range of 10 MHz to 10 GHz, and f
is the volume filling factor of the plasma in the cavity. We find that the
values of k/f for the lobes of NGC 1399 are ~93 and ~190, and those of the
lobes of NGC 4649 are ~15000 and ~12000. We conclude that the assumed spectrum
describes the electron distribution in the lobes of NGC 1399 reasonably well,
and that there are few entrained particles. For NGC 4649, either there are many
entrained particles or the model spectrum does not accurately describe the
population of electrons.Comment: 8 pages, 2 figures, accepted for publication in MNRA
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