15,290 research outputs found
Quantum Evolution of Inhomogeneities in Curved Space
We obtain the renormalized equations of motion for matter and semi-classical
gravity in an inhomogeneous space-time. We use the functional Schrodinger
picture and a simple Gaussian approximation to analyze the time evolution of
the model, and we establish the renormalizability of this
non-perturbative approximation. We also show that the energy-momentum tensor in
this approximation is finite once we consider the usual mass and coupling
constant renormalizations, without the need of further geometrical
counter-terms.Comment: 22 page
Literacy: A cultural influence on functional left-right differences in the inferior parietal cortex
The current understanding of hemispheric interaction is limited. Functional hemispheric specialization is likely to depend on both genetic and environmental factors. In the present study we investigated the importance of one factor, literacy, for the functional lateralization in the inferior parietal cortex in two independent samples of literate and illiterate subjects. The results show that the illiterate group are consistently more right-lateralized than their literate controls. In contrast, the two groups showed a similar degree of left-right differences in early speech-related regions of the superior temporal cortex. These results provide evidence suggesting that a cultural factor, literacy, influences the functional hemispheric balance in reading and verbal working memory-related regions. In a third sample, we investigated grey and white matter with voxel-based morphometry. The results showed differences between literacy groups in white matter intensities related to the mid-body region of the corpus callosum and the inferior parietal and parietotemporal regions (literate > illiterate). There were no corresponding differences in the grey matter. This suggests that the influence of literacy on brain structure related to reading and verbal working memory is affecting large-scale brain connectivity more than grey matter per se
Final state interaction in with I=1/2 and 3/2 channels
The final state interaction contribution to decays is computed for the
channel within a light-front relativistic three-body model for
the final state interaction. The rescattering process between the kaon and two
pions in the decay channel is considered. The off-shell decay amplitude is a
solution of a four-dimensional Bethe-Salpeter equation, which is decomposed in
a Faddeev form. The projection onto the light-front of the coupled set of
integral equations is performed via a quasi-potential approach. The S-wave
interaction is introduced in the resonant isospin and the
non-resonant isospin channels. The numerical solution of the light-front
tridimensional inhomogeneous integral equations for the Faddeev components of
the decay amplitude is performed perturbatively. The loop-expansion converges
fast, and the three-loop contribution can be neglected in respect to the
two-loop results for the practical application. The dependence on the model
parameters in respect to the input amplitude at the partonic level is exploited
and the phase found in the experimental analysis, is fitted with an appropriate
choice of the real weights of the isospin components of the partonic amplitude.
The data suggests a small mixture of total isospin to the dominant
one. The modulus of the unsymmetrized decay amplitude, which presents a deep
valley and a following increase for masses above GeV, is fairly
reproduced. This suggests the assignment of the quantum numbers to the
isospin 1/2 resonance
Periodic Anderson model with electron-phonon correlated conduction band
This paper reports dynamical mean field calculations for the periodic
Anderson model in which the conduction band is coupled to phonons. Motivated in
part by recent attention to the role of phonons in the -
transition in Ce, this model yields a rich and unexpected phase diagram which
is of intrinsic interest. Specifically, above a critical value of the
electron-phonon interaction, a first order transition with two coexisting
phases develops in the temperature-hybridization plane, which terminates at a
second order critical point. The coexisting phases display the familiar Kondo
screened and local moment character, yet they also exhibit pronounced polaronic
and bipolaronic properties, respectively.Comment: 4 pages, 6 figure
Exploring the alignment of first-year summative assessments with Bloom’s Taxonomy: A longitudinal study
The correlation between the level of difficulty of assessments, Bloom’s Taxonomy as well as pass rates of courses has been a seriously under-researched area in South Africa. In this study, we proposed the revised Bloom’s taxonomy level of difficulty index, before we examined 112 first-year 2017‒2019 final and supplementary assessment papers from the Economic and Management Sciences Faculty of a university in Western Cape.
The descriptive statistics showed that these assessment papers are different in terms of duration, total marks, type of questions asked as well as pass rates. It was also found that these first-year summative assessments asked questions mainly at levels two (understand) and three (apply) of the revised Bloom’s Taxonomy. In addition, the correlation and econometric analysis did not find a strong correlation between the level of difficulty index and pass rates. Nonetheless, the above-mentioned results need to be interpreted with great caution, because strictly speaking, one should also control for differences in other characteristics (e.g., students’ personal characteristics, school characteristics and lecture attendance).
To conclude, there is no explicit national policy that guides higher education institutions (HEIs) on how to use Bloom’s or any other taxonomy to assess students at the appropriate National Qualifications Framework (NQF) level. Hence, our findings suggest that there is a need for a national assessment policy framework to guide HEIs on how to assess undergraduate students at different cognitive levels as required by the NQF
Molecular mechanism of influenza A NS1-mediated TRIM25 recognition and inhibition
RIG-I is a viral RNA sensor that induces the production of type I interferon (IFN) in response to infection with a variety of viruses. Modification of RIG-I with K63-linked poly-ubiquitin chains, synthesised by TRIM25, is crucial for activation of the RIG-I/MAVS signalling pathway. TRIM25 activity is targeted by influenza A virus non-structural protein 1 (NS1) to suppress IFN production and prevent an efficient host immune response. Here we present structures of the human TRIM25 coiled-coil-PRYSPRY module and of complexes between the TRIM25 coiled-coil domain and NS1. These structures show that binding of NS1 interferes with the correct positioning of the PRYSPRY domain of TRIM25 required for substrate ubiquitination and provide a mechanistic explanation for how NS1 suppresses RIG-I ubiquitination and hence downstream signalling. In contrast, the formation of unanchored K63-linked poly-ubiquitin chains is unchanged by NS1 binding, indicating that RING dimerisation of TRIM25 is not affected by NS1
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