15,444 research outputs found
Thermal conductivity and diffusion-mediated localization in Fe_{1-x}Cr_{x} Alloys
We apply a new Kubo-Greenwood type formula combined with a generalized
Feynman diagram- matic technique to report a first principles calculation of
the thermal transport properties of disordered Fe_{1-x}Cr_{x} alloys. The
diagrammatic approach simplifies the inclusion of disorder-induced scattering
effects on the two particle correlation functions and hence renormalizes the
heat current operator to calculate configuration averaged lattice thermal
conductivity and diffusivity. The thermal conductivity K(T) in the present case
shows an approximate quadratic T-dependence in the low temperature regime (T <
20 K), which subsequently rises smoothly to a T-independent saturated value at
high T . A numerical estimate of mobility edge from the thermal diffusivity
data yields the fraction of localized states. It is concluded that the complex
disorder scattering processes, in force-constant dominated disorder alloys such
as Fe-Cr, tend to localize the vibrational modes quite significantly.Comment: 5 pages, 5 figure
Matter induced charge symmetry breaking and pion form factor in nuclear medium
Medium modification of pion form factor has been evaluated in asymmetric
nuclear matter. It is shown that both the shape and the pole position of the
pion form factor in dense asymmetric nuclear matter is different from its
vacuum counterpart with - mixing. This is due to the density and
asymmetry dependent - mixing which could even dominate over its
vacuum counterpart in matter. Effect of the in-medium pion factor on
experimental observables {\it e.g.}, invariant mass distribution of lepton
pairs has been demonstrated.Comment: Final Version to appear in Jour. Phys.
Thermal Radiation from Nucleons and Mesons
Thermal photon emission rates due to meson-nucleon interactions have been
evaluated. An exhaustive set of reactions involving p(\bar p), n(\bar n), rho,
omega, a_1, pi and eta is seen to provide a sizeable contribution to the
emission rate from hot hadronic matter. Contributions from baryonic resonances
are found to be negligibly small
Low Ply Drawings of Trees
We consider the recently introduced model of \emph{low ply graph drawing}, in
which the ply-disks of the vertices do not have many common overlaps, which
results in a good distribution of the vertices in the plane. The
\emph{ply-disk} of a vertex in a straight-line drawing is the disk centered at
it whose radius is half the length of its longest incident edge. The largest
number of ply-disks having a common overlap is called the \emph{ply-number} of
the drawing.
We focus on trees. We first consider drawings of trees with constant
ply-number, proving that they may require exponential area, even for stars, and
that they may not even exist for bounded-degree trees. Then, we turn our
attention to drawings with logarithmic ply-number and show that trees with
maximum degree always admit such drawings in polynomial area.Comment: This is a complete access version of a paper that will appear in the
proceedings of GD201
Supervised machine learning based multi-task artificial intelligence classification of retinopathies
Artificial intelligence (AI) classification holds promise as a novel and
affordable screening tool for clinical management of ocular diseases. Rural and
underserved areas, which suffer from lack of access to experienced
ophthalmologists may particularly benefit from this technology. Quantitative
optical coherence tomography angiography (OCTA) imaging provides excellent
capability to identify subtle vascular distortions, which are useful for
classifying retinovascular diseases. However, application of AI for
differentiation and classification of multiple eye diseases is not yet
established. In this study, we demonstrate supervised machine learning based
multi-task OCTA classification. We sought 1) to differentiate normal from
diseased ocular conditions, 2) to differentiate different ocular disease
conditions from each other, and 3) to stage the severity of each ocular
condition. Quantitative OCTA features, including blood vessel tortuosity (BVT),
blood vascular caliber (BVC), vessel perimeter index (VPI), blood vessel
density (BVD), foveal avascular zone (FAZ) area (FAZ-A), and FAZ contour
irregularity (FAZ-CI) were fully automatically extracted from the OCTA images.
A stepwise backward elimination approach was employed to identify sensitive
OCTA features and optimal-feature-combinations for the multi-task
classification. For proof-of-concept demonstration, diabetic retinopathy (DR)
and sickle cell retinopathy (SCR) were used to validate the supervised machine
leaning classifier. The presented AI classification methodology is applicable
and can be readily extended to other ocular diseases, holding promise to enable
a mass-screening platform for clinical deployment and telemedicine.Comment: Supplemental material attached at the en
Improving the Eleventh Graders's Recount Text Writing Through Mind Mapping Technique at SMA PSKD 7 Depok
The objective of this research was to improve the eleventh graders' recount text writing skill. To attain the objective a two-cycled classroom action research was conducted in SMA PSKD 7 Depok. The 28 students of the eleventh graders who participated in this research were taught recount text through mind mapping technique. The quantitative data, collected using tests, were analyzed by using statistical analysis technique. The qualitative data, collected using observation sheets and interview guide, were analyzed by using descriptive analysis technique. The results indicated that the mind mapping technique improved the eleventh graders' recount text writing skill, as shown by the increase of the mean scores of the tests conducted, i.e. 52,61 (in the pretest) to 70.61 ( post-test of cycle 1) to 80.29 (post-test of cycle 2). Based on the findings, it could be concluded that through implementation of mind mapping technique, students' recount text writing skill could improve.
Keywords: Mind mapping technique, writing skill, classroom action researc
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