379 research outputs found
An Automatic Self-explanation Sample Answer Generation with Knowledge Components in a Math Quiz
Part of the Lecture Notes in Computer Science book series (LNCS, volume 13356)Little research has addressed how systems can use the learning process of self-explanation to provide scaffolding or feedback. Here, we propose a model automatically generating sample self-explanations with knowledge components required to solve a math quiz. The proposed model contains three steps: vectorization, clustering, and extraction. In an experiment using 1434 self-explanation answers from 25 quizzes, we found 72% of the quizzes generated sample answers with all necessary knowledge components. The similarity between human-created and machine-generated sentences was 0.719, with a significant correlation of Râ=â0.48 for the best performing generation model by BERTScore. These results suggest that our model can generate sample answers with the necessary key knowledge components and be further improved by using the BERTScore
Theory of Static and Dynamic Antiferromagnetic Vortices in LSCO Superconductors
A key prediction of the SO(5) theory is the antiferromagnetic vortex state.
Recent neutron scattering experiment on LSCO superconductors revealed enhanced
antiferromagnetic order in the vortex state. Here we review theoretical
progress since the original proposal and present a theory of static and dynamic
antiferromanetic vortices in LSCO superconductors. It is shown that the
antiferromagnetic region induced by the vortices can be greater than the
coherence length, due to the light effective mass of the dynamic
antiferromagnetic fluctuations at optimal doping, and close promixity to the
antiferromagentic state in the underdoped regime. Systematic experiments are
proposed to unambiguously determine that the field induced magnetic scattering
originates from the vortices and not from the bulk.Comment: Invited Talk at SNS 200
Absence of in vivo mutagenicity of multi-walled carbon nanotubes in single intratracheal instillation study using F344 gpt delta rats
Abstract
Introduction
It is known that fibrous particles of micrometer length, such as carbon nanotubes, which have same dimensions as asbestos, are carcinogenic. Carcinogenicity of nanomaterials is strongly related to inflammatory reactions; however, the genotoxicity mechanism(s) is unclear. Indeed, inconsistent results on genotoxicity of multi-walled carbon nanotubes (MWCNTs) have been shown in several reports. Therefore, we analyzed the in vivo genotoxicity induced by an intratracheal instillation of straight MWCNTs in rats using a different test system\u2014the Pig-a gene mutation assay\u2014that can reflect the genotoxicity occurring in the bone marrow. Since lungs were directly exposed to MWCNTs upon intratracheal instillation, we also performed the gpt assay using the lungs.
Findings
We detected no significant differences in Pig-a mutant frequencies (MFs) between the MWCNT-treated and control rats. Additionally, we detected no significant differences in gpt MFs in the lung between the MWCNT-treated and control rats.
Conclusions
Our findings indicated that a single intratracheal instillation of MWCNTs was non-mutagenic to both the bone marrow and lung of rats
A 90-day Feeding Toxicity Study of l-Serine in Male and Female Fischer 344 Rats
A subchronic feeding study of l-serine (l-Ser) was conducted with groups of 10
male and 10 female Fischer 344 rats fed a powder diet containing 0, 0.06, 0.5,
1.5 or 5.0% concentrations of l-Ser for 90 days. There were no toxicologically
significant, treatment-related changes with regards to body weight, food intake,
water intake or urinalysis data. In several of the hematology, serum
biochemistry and organ weight parameters, significant changes were observed
between some of the treated groups and the controls. All these changes, however,
were subtle and lacked any corresponding pathological findings. In addition, the
increased or decreased values remained within the range of the historical
control values. In fact, histopathological assessment revealed only sporadic
and/or spontaneous lesions. In conclusion, the no-observed-adverse-effect-level
(NOAEL) for l-Ser was, therefore, determined to be at least a dietary dose of
5.0% (2765.0 mg/kg body weight/day for males and 2905.1 mg/kg body weight/day
for females) under the present experimental conditions
Doped Stripes in Models for the Cuprates Emerging from the One-hole Properties of the Insulator
The extended and standard t-J models are computationally studied on ladders
and planes, with emphasis on the small J/t region. At couplings compatible with
photoemission results for undoped cuprates, half-doped stripes separating
-shifted antiferromagnetic (AF) domains are found, as in Tranquada's
interpretation of neutron experiments. Our main result is that the elementary
stripe `"building-block" resembles the properties of hole at small J/t,
with robust AF correlations across-the-hole induced by the local tendency of
the charge to separate from the spin (G. Martins {\it et al.}, Phys. Rev. B{\bf
60}, R3716 (1999)). This suggests that the seed of half-doped stripes already
exists in the unusual properties of the insulating parent compound.Comment: 4 pages, LateX, 4 figures, to appear on Phys. Rev. Let
Field-Induced Uniform Antiferromagnetic Order Associated with Superconductivity in PrLaCeCuO
Strong correlation between field-induced antiferromagnetic (AF) order and
superconductivity is demonstrated for an electron-doped cuprate superconductor,
PrLaCeCuO (PLCCO). In addition to the specimen with
(which is close to the AF phase boundary, ), we show that
the one with ( K at zero field) also exhibits the
field-induced AF order with a reduced magnitude of the induced moment. The
uniform muon Knight shift at a low magnetic field ( Oe) indicates
that the AF order is not localized within the cores of flux lines, which is in
a marked contrast with theoretical prediction for hole-doped cuprates. The
presence of anomalous non-diagonal hyperfine coupling between muons and Pr ions
is also demonstrated in detail.Comment: 8 pages, 5 figures, to be published in J. Phys. Soc. Jp
Indications of Spin-Charge Separation at Short Distance and Stripe Formation in the Extended t-J Model on Ladders and Planes
The recently discussed tendency of holes to generate nontrivial spin
environments in the extended two-dimensional t-J model (G. Martins, R. Eder,
and E. Dagotto, Phys. Rev. B{\bf 60}, R3716 (1999)) is here investigated using
computational techniques applied to ladders with several number of legs. This
tendency is studied also with the help of analytic spin-polaron approaches
directly in two dimensions. Our main result is that the presence of robust
antiferromagnetic correlations between spins located at both sides of a hole
either along the x or y axis, observed before numerically on square clusters,
is also found using ladders, as well as applying techniques based on a
string-basis expansion. This so-called "across-the-hole" nontrivial structure
exists even in the two-leg spin-gapped ladder system, and leads to an effective
reduction in dimensionality and spin-charge separation at short-distances, with
a concomitant drastic reduction in the quasiparticle (QP) weight Z. In general,
it appears that holes tend to induce one-dimensional-like spin arrangements to
improve their mobility. Using ladders it is also shown that the very small
J/t0.1 regime of the standard t-J model may be more realistic than
anticipated in previous investigations, since such regime shares several
properties with those found in the extended model at realistic couplings.
Another goal of the present article is to provide additional information on the
recently discussed tendencies to stripe formation and spin incommensurability
reported for the extended t-J model.Comment: 14 pages, 21 figures, LateX, submited to Phys. Rev.
Effective gauge field theory of the t-J model in the charge-spin separated state and its transport properties
We study the slave-boson t-J model of cuprates with high superconducting
transition temperatures, and derive its low-energy effective field theory for
the charge-spin separated state in a self-consistent manner. The phase degrees
of freedom of the mean field for hoppings of holons and spinons can be regarded
as a U(1) gauge field, . The charge-spin separation occurs below certain
temperature, , as a deconfinement phenomenon of the dynamics of
. Below certain temperature , the spin-gap
phase develops as the Higgs phase of the gauge-field dynamics, and
acquires a mass . The effective field theory near takes the
form of Ginzburg-Landau theory of a complex scalar field coupled with
, where represents d-wave pairings of spinons. Three
dimensionality of the system is crucial to realize a phase transition at
.
By using this field theory, we calculate the dc resistivity . At , is proportional to . At , it deviates
downward from the -linear behavior as . When the system is near (but not) two dimensional, due to the compactness
of the phase of the field , the exponent deviates from its
mean-field value 1/2 and becomes a nonuniversal quantity which depends on
temperature and doping. This significantly improves the comparison with the
experimental data
Thematic Working Group 3 - Inclusion of Excluded Populations : Access and Learning Optimization via IT in the Post-Pandemic Era
Thematic Working Group (TWG) 3âs theme is âInclusion of excluded populations: access and learning optimization via IT in the post-pandemic eraâ. A focal concern is established by the presence of the first word â âinclusionâ â and how this relates to âexcluded populationsâ. Much of the research in this field has focused on inclusion for individuals; however, the evidence shows that educational exclusion has multiple dimensions (Passey, 2014). To accommodate this within the current focus, therefore, identifying key dimensions of âexcluded populationsâ will be a key concern of this document. âAccessâ will be considered beyond physical technology access, involving aspects of accessibility, agency and empowerment. These aspects relate to a definition of access that concerns the needs for individuals to develop and have digital capabilities and abilities to select applications appropriate to purpose, as discussed, for example, by Helsper (2021) and Passey et al. (2018). Taking this wider concern for access, âlearning optimizationâ will be explored as a term that highlights the need to focus on technological access and provision enabling successful outcomes. Given the fact that the intention of the work of TWG3 is to explore findings in the âpost-pandemicâ context, communication technologies as well as just information technology, âITâ, are clearly important and need to be considered. Additionally, exclusion factors to be addressed need to be clearly identified so that inclusion can be accommodated and ensured in the context of specific excluded populations. However, inclusion should not be implemented as an imposition in the context of digital technologies, as some populations do not wish to use digital technologies (Wetmore, 2007), and in this respect the issue of the need to acknowledge diversity is important
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