3,329 research outputs found
Evidence for a preformed Cooper pair model in the pseudogap spectra of a Ca10(Pt4As8)(Fe2As2)5 single crystal with a nodal superconducting gap
For high-Tc superconductors, clarifying the role and origin of the pseudogap
is essential for understanding the pairing mechanism. Among the various models
describing the pseudogap, the preformed Cooper pair model is a potential
candidate. Therefore, we present experimental evidence for the preformed Cooper
pair model by studying the pseudogap spectrum observed in the optical
conductivity of a Ca10(Pt4As8)(Fe2As2)5 (Tc = 34.6 K) single crystal. We
observed a clear pseudogap structure in the optical conductivity and observed
its temperature dependence. In the superconducting (SC) state, one SC gap with
a gap size of {\Delta} = 26 cm-1, a scattering rate of 1/{\tau} = 360 cm-1 and
a low-frequency extra Drude component were observed. Spectral weight analysis
revealed that the SC gap and pseudogap are formed from the same Drude band.
This means that the pseudogap is a gap structure observed as a result of a
continuous temperature evolution of the SC gap observed below Tc. This provides
clear experimental evidence for the preformed Cooper pair model.Comment: 15 pages, 4 figure
Graph Neural Network-Aided Exploratory Learning for Community Detection with Unknown Topology
In social networks, the discovery of community structures has received
considerable attention as a fundamental problem in various network analysis
tasks. However, due to privacy concerns or access restrictions, the network
structure is often unknown, thereby rendering established community detection
approaches ineffective without costly network topology acquisition. To tackle
this challenge, we present META-CODE, a novel end-to-end solution for detecting
overlapping communities in networks with unknown topology via exploratory
learning aided by easy-to-collect node metadata. Specifically, META-CODE
consists of three iterative steps in addition to the initial network inference
step: 1) node-level community-affiliation embeddings based on graph neural
networks (GNNs) trained by our new reconstruction loss, 2) network exploration
via community affiliation-based node queries, and 3) network inference using an
edge connectivity-based Siamese neural network model from the explored network.
Through comprehensive evaluations using five real-world datasets, we
demonstrate that META-CODE exhibits (a) its superiority over benchmark
community detection methods, (b) empirical evaluations as well as theoretical
findings to see the effectiveness of our node query, (c) the influence of each
module, and (d) its computational efficiency.Comment: 15 pages, 8 figures, 5 tables; its conference version was presented
at the ACM International Conference on Information and Knowledge Management
(CIKM 2022
Null and time-like geodesics in Kerr-Newman black hole exterior
We study the null and time-like geodesics of the light and the neutral
particles respectively in the exterior of Kerr-Newman black holes. The geodesic
equations are known to be written as a set of first-order differential
equations in Mino time from which the angular and radial potentials can be
defined. We classify the roots for both potentials, and mainly focus on those
of the radial potential with an emphasis on the effect from the charge of the
black holes. We then obtain the solutions of the trajectories in terms of the
elliptical integrals and the Jacobian elliptic functions for both null and
time-like geodesics, which are manifestly real functions of the Mino time that
the initial conditions can be explicitly specified. We also describe the
details of how to reduce those solutions into the cases of the spherical
orbits. The effect of the black hole's charge decreases the radii of the
spherical motion of the light and the particle for both direct and retrograde
motions. In particular, we focus on the light/particle boomerang of the
spherical orbits due to the frame dragging from the back hole's spin with the
effect from the charge of the black hole. To sustain the change of the
azimuthal angle of the light rays, say for example during the
whole trip, the presence of the black hole's charge decreases the radius of the
orbit and consequently reduces the needed values of the black hole's spin. As
for the particle boomerang, the particle's inertia renders smaller change of
the angle as compared with the light boomerang. Moreover, the
black hole's charge also results in the smaller angle change of
the particle than that in the Kerr case. The implications of the obtained
results to observations are discussed.Comment: 50 pages, 18 figure
Inspiral and Plunging Orbits in Kerr-Newman Spacetimes
We present the analytical solutions for the trajectories that spiral and
plunge inward the event horizon along the timelike geodesics of particles
following general non-equatorial paths within Kerr-Newman spacetimes. Our
studies encompass both bound and unbound motions. The solutions can be written
in terms of the elliptical integrals and the Jacobian elliptic functions of
manifestly real functions of the Mino time, and can respectively reduce to the
Kerr, Reissner-Nordstrm, and Schwarzschild black holes in certain
limits of the spin and charge of the black holes. The results can be compared
with some of the known ones restricted in the equatorial plane. These explicit
solutions may find applications such as the black hole accretion.Comment: 28 pages, 9 figure
Effects of text structures on interest and memory in expository texts
Abstract: The purpose of the study was to examine the effects of expository-text structures on interest and memory. Three methods of structuring texts used in the study were detailing, contextualizing, and questioning strategies. Students in grades 6 and 7 participated in the study. Two experiments were conducted. In the experiment 1, a within-subject design was used to investigate differences in text interests among different forms of texts. In the experiment 2, a between-subject design was used to investigate the effects of the textstructuring strategies on text comprehension and memory as well as text interest. Results of the experiment 1 showed that students selected contextualized texts as the most interesting. The reason was that students felt contextualized texts practically relevant to their real lives. In addition, texts constructed by using the strategies showed significantly higher levels of interest than the base text where no strategies were applied. However, in the experiment 2, no significant differences in text interest were found among the different forms of texts. In addition, scores on the text comprehension and memory tests were significantly higher in the base and questioning-strategy texts than in the other two forms of texts. Especially, the lowest performance was found in the contextualized texts. The results of the study provide practical implications on how to structure expository texts commonly used in school to enhance motivation and learning outcomes. Specifically, the results suggested that it would be the most desirable to construct text contents so as to create cognitive conflicts to readers, when text interest, comprehension, and memory are all considered
Oldenlandia diffusa Promotes Antiproliferative and Apoptotic Effects in a Rat Hepatocellular Carcinoma with Liver Cirrhosis
Oldenlandia diffusa (OD) is commonly used with various diseases such as cancer, arthritis, and autoimmune disease. Liver cirrhosis is a predominant risk factor for hepatocellular carcinoma (HCC). Here, we show that the therapeutic effect of OD, which was investigated both in vitro and chemically, induced HCC model. OD significantly enhanced apoptosis and antiproliferative activity and reduced migration ability of HCC cells. In vivo, OD was treated twice a day for 28 days after confirmed HCC model through 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) imaging. The survival in OD treated groups was shown to have a greater therapeutic effect than the control group. 28 days after OD treatment, OD treated groups resulted in a significant reduction in tumor number, size, (18)F-FDG uptake, and serum levels such as alanine transaminase, aspartate transaminase, and alkaline phosphate compared to the control group. Also, proliferated cells in tumor sites by OD were reduced compared to the control group. Furthermore, several rats in OD treated group survived over 60 days and liver morphology of these rats showed the difference between tumor mass and normal tissue. These results suggest that OD may have antiproliferative activity, inhibition of metastasis, and apoptotic effects in chemically induced HCC model and can have the potential use for clinical application as anticancer drug of the herbal extract
Temperature dependence of the superconducting energy gaps in Ca9.35La0.65(Pt-3 As-8)(Fe2As2)(5) single crystal
We measured the optical reflectivity R(ω) for an underdoped (Ca0.935La0.065)10(Pt3As8)(Fe2As2)5 single crystal and obtained the optical conductivity σ1(ω) using the K-K transformation. The normal state σ1(ω) at 30 K is well fitted by a Drude-Lorentz model with two Drude components (ωp1 = 1446 cm-1 and ωp2 = 6322 cm-1) and seven Lorentz components. Relative reflectometry was used to accurately determine the temperature dependence of the superconducting gap at various temperatures below Tc. The results clearly show the opening of a superconducting gap with a weaker second gap structure; the magnitudes for the gaps are estimated from the generalized Mattis-Bardeen model to be Δ1 = 30 and Δ2 = 50 cm-1, respectively, at T = 8 K, which both decrease with increasing temperature. The temperature dependence of the gaps was not consistent with one-band BCS theory but was well described by a two-band (hence, two gap) BCS model with interband interactions. The temperature dependence of the superfluid density is flat at low temperatures, indicating an s-wave full-gap superconducting state. © The Author(s) 2018.1
- …