2,446 research outputs found
Latin Vocabulary Knowledge and the Readability of Latin Texts: A Preliminary Study
Studies have found a strong correlation between vocabulary knowledge and L2 reading comprehension. This preliminary study of the readability of Latin texts considers how common measures of lexical complexity (word length, word frequency, lexical sophistication, lexical density, and lexical variation) can inform instructors about what texts have the least (and most) lexical complexity. By defining several key measurements of Latin lexical complexity, we establish a provisional account of the lexical difficulty of some familiar Latin texts that are frequently taught in elementary, intermediate, and advanced levels, and propose LexR, a single, informative, integrated score that provides a sense of the comparative lexical complexity of Latin texts
Semantic metrics
In the context of the Semantic Web, many ontology-related operations, e.g. ontology ranking, segmentation, alignment, articulation, reuse, evaluation, can be boiled down to one fundamental operation: computing the similarity and?or dissimilarity among ontological entities, and in some cases among ontologies themselves. In this paper, we review standard metrics for computing distance measures and we propose a series of semantic metrics. We give a formal account of semantic metrics drawn from a variety of research disciplines, and enrich them with semantics based on standard Description Logic constructs. We argue that concept-based metrics can be aggregated to produce numeric distances at ontology-level and we speculate on the usability of our ideas through potential areas
Experimental investigation of muscular neurotization in the rat
Reinnervation of a free muscle graft by nerves from an adjacent intact muscle is called muscular neurotization. This paper investigates the mechanisms and stimuli responsible for muscular neurotization in the rat. Sternohyoid or sternomastoid muscles were transplanted as free muscle grafts to the ventral surface of an intact sternohyoid muscle (feeder muscle). After several weeks the graft and underlying feeder muscle were removed together, frozen, serially sectioned, stained, and carefully examined for the presence or absence of nerves. It was concluded from a series of experiments that in this model muscular neurotization is a form of nerve regeneration. In order for muscular neurotization to occur, it is necessary to have (1) injury to the nerves of the intact feeder muscle and (2) a pathway upon which the regenerating nerves may grow into the graft.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50139/1/880100607_ftp.pd
Full-scale testing and analysis of fuselage structure
This paper presents recent results from a program in the Boeing Commercial Airplane Group to study the behavior of cracks in fuselage structures. The goal of this program is to improve methods for analyzing crack growth and residual strength in pressurized fuselages, thus improving new airplane designs and optimizing the required structural inspections for current models. The program consists of full-scale experimental testing of pressurized fuselage panels in both wide-body and narrow-body fixtures and finite element analyses to predict the results. The finite element analyses are geometrically nonlinear with material and fastener nonlinearity included on a case-by-case basis. The analysis results are compared with the strain gage, crack growth, and residual strength data from the experimental program. Most of the studies reported in this paper concern the behavior of single or multiple cracks in the lap joints of narrow-body airplanes (such as 727 and 737 commercial jets). The phenomenon where the crack trajectory is curved creating a 'flap' and resulting in a controlled decompression is discussed
Discovery of a flux-related change of the cyclotron line energy in Her X-1
We present the results of ten years of repeated measurements of the Cyclotron
Resonance Scattering Feature (CRSF) in the spectrum of the binary X-ray pulsar
Her X-1 and report the discovery of a positive correlation of the centroid
energy of this absorption feature in pulse phase averaged spectra with source
luminosity.Our results are based on a uniform analysis of observations bythe
RXTE satellite from 1996 to 2005, using sufficiently long observations of 12
individual 35-day Main-On states of the source. The mean centroid energy E_c of
the CRSF in pulse phase averaged spectra of Her X-1 during this time is around
40 keV, with significant variations from one Main-On state to the next. We find
that the centroid energy of the CRSF in Her X-1 changes by ~5% in energy for a
factor of 2 in luminosity. The correlation is positive, contrary to what is
observed in some high luminosity transient pulsars. Our finding is the first
significant measurement of a positive correlation between E_c and luminosity in
any X-ray pulsar. We suggest that this behaviour is expected in the case of
sub-Eddington accretion and present a calculation of a quantitative estimate,
which is very consistent with the effect observed in Her X-1.We urge that Her
X-1 is regularly monitored further and that other X-ray pulsars are
investigated for a similar behaviour.Comment: 4 pages, 2 figures, accepted by A&A Letter
Expression and localization of estrogen receptor-β in annulus cells of the human intervertebral disc and the mitogenic effect of 17-β-estradiol in vitro
BACKGROUND: Recent evidence suggests that estrogens exert effects in different tissues throughout the body, and that the estrogen receptor β (ERβ) may be important for the action of estrogen (17-β-estradiol) on the skeleton. The cellular localization of ERβ in the human intervertebral disc, however, has not yet been explored. METHODS: Human disc tissue and cultured human disc cells were used for immunocytochemical localization of ERβ. mRNA was isolated from cultured human disc cells, and RT-PCR amplification of ERβ was employed to document molecular expression of this receptor. Cultured human disc cells were tested to determine if 17-β-estradiol stimulated cell proliferation. RESULTS: In this report data are presented which provide evidence for ERβ gene expression in human intervertebral disc cells in vivo and in vitro. Culture of annulus cells in the presence of 10(-7) M 17-β-estradiol significantly increased cell proliferation. CONCLUSIONS: These data provide new insight into the biology of cells in the annulus of the intervertebral disc
Decision-making flexibility in New Caledonian crows, young children and adult humans in a multi-dimensional tool-use task
The ability to make profitable decisions in natural foraging contexts may be influenced by an additional requirement of tool-use, due to increased levels of relational complexity and additional work-effort imposed by tool-use, compared with simply choosing between an immediate and delayed food item. We examined the flexibility for making the most profitable decisions in a multi-dimensional tool-use task, involving different apparatuses, tools and rewards of varying quality, in 3-5-year-old children, adult humans and tool-making New Caledonian crows (Corvus moneduloides). We also compared our results to previous studies on habitually tool-making orangutans (Pongo abelii) and non-tool-making Goffin’s cockatoos (Cacatua goffiniana). Adult humans, cockatoos and crows, but not children and orangutans, did not select a tool when it was not necessary, which was the more profitable choice in this situation. Adult humans, orangutans and cockatoos, but not crows and children, were able to refrain from selecting non-functional tools. By contrast, the birds, but not the primates tested, struggled to attend to multiple variables—where two apparatuses, two tools and two reward qualities were presented simultaneously—without extended experience. These findings indicate: (1) in a similar manner to humans and orangutans, New Caledonian crows and Goffin’s cockatoos can flexibly make profitable decisions in some decision-making tool-use tasks, though the birds may struggle when tasks become more complex; (2) children and orangutans may have a bias to use tools in situations where adults and other tool-making species do not. © 2020 Miller et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
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