235 research outputs found
A Bernstein-von Mises theorem in the nonparametric right-censoring model
In the recent Bayesian nonparametric literature, many examples have been
reported in which Bayesian estimators and posterior distributions do not
achieve the optimal convergence rate, indicating that the Bernstein-von
Mises theorem does not hold. In this article, we give a positive result in
this direction by showing that the Bernstein-von Mises theorem holds in
survival models for a large class of prior processes neutral to the right. We
also show that, for an arbitrarily given convergence rate n^{-\alpha} with
0<\alpha \leq 1/2, a prior process neutral to the right can be chosen so that
its posterior distribution achieves the convergence rate n^{-\alpha}.Comment: Published by the Institute of Mathematical Statistics
(http://www.imstat.org) in the Annals of Statistics
(http://www.imstat.org/aos/) at http://dx.doi.org/10.1214/00905360400000052
Origin of High-Temperature Superconductivity in Compressed LaH
Room-temperature superconductivity has been one of the most challenging
subjects in modern physics. Recent experiments reported that lanthanum hydride
LaH (1) raises a superconducting transition temperature
up to 260 (or 215) K at high pressures around 190 (150)
GPa. Here, based on first-principles calculations, we reveal the existence of
topological Dirac-nodal-line (DNL) states in compressed LaH. Remarkably,
the DNLs protected by the combined inversion and time-reversal symmetry and the
rotation symmetry create a van Hove singularity (vHs) near the Fermi energy,
giving rise to large electronic density of states. Contrasting with other La
hydrides containing cationic La and anionic H atoms, LaH shows a
peculiar characteristic of electrical charges with anionic La and both cationic
and anionic H species, caused by a strong hybridization of the La and H
orbitals. We find that a large number of electronic states at the vHs are
strongly coupled to the H-derived high-frequency phonon modes that are induced
via the unusual, intricate bonding network of LaH, thereby yielding a
high . Our findings not only elucidate the microscopic origin of the
observed high- BCS-type superconductivity in LaH, but also
pave the route for achieving room-temperature topological superconductors in
compressed hydrogen-rich compounds.Comment: 9 pages, 11 figure
Examining the links between general strain and control theories: an investigation of delinquency in South Korea
In modifying general strain theory (GST), Agnew has accepted the control-related variables as conditioning variables to moderate or mediate the casual process through strain into delinquency. In this regard, this study aims to empirically and theoretically address the void of connecting traditional and redefined self-control variables to GST. To explore this issue, the current study employed data derived from the Korea Children and Youth Panel Study (KCYPS). Specifically, three waves (2012, 2013, and 2014) were used to test hypotheses from GST and control theories. Both trait-based low self-control and revised self-control partially mediated the relationship between strain and delinquency. However, only redefined self-control significantly interacted with strain in producing delinquency. The current research reveals the possible integration of redefined control theory and GST
Rydberg Quantum Wires for Maximum Independent Set Problems with Nonplanar and High-Degree Graphs
One prominent application of near-term quantum computing devices is to solve
combinatorial optimization such as non-deterministic polynomial-time hard
(NP-hard) problems. Here we present experiments with Rydberg atoms to solve one
of the NP-hard problems, the maximum independent set (MIS) of graphs. We
introduce the Rydberg quantum wire scheme with auxiliary atoms to engineer
long-ranged networks of qubit atoms. Three-dimensional (3D) Rydberg-atom arrays
are constructed, overcoming the intrinsic limitations of two-dimensional
arrays. We demonstrate Kuratowski subgraphs and a six-degree graph, which are
the essentials of non-planar and high-degree graphs. Their MIS solutions are
obtained by realizing a programmable quantum simulator with the quantum-wired
3D arrays. Our construction provides a way to engineer many-body entanglement,
taking a step toward quantum advantages in combinatorial optimization.Comment: 8 pages, 4 figure
GraNNDis: Efficient Unified Distributed Training Framework for Deep GNNs on Large Clusters
Graph neural networks (GNNs) are one of the most rapidly growing fields
within deep learning. According to the growth in the dataset and the model size
used for GNNs, an important problem is that it becomes nearly impossible to
keep the whole network on GPU memory. Among numerous attempts, distributed
training is one popular approach to address the problem. However, due to the
nature of GNNs, existing distributed approaches suffer from poor scalability,
mainly due to the slow external server communications.
In this paper, we propose GraNNDis, an efficient distributed GNN training
framework for training GNNs on large graphs and deep layers. GraNNDis
introduces three new techniques. First, shared preloading provides a training
structure for a cluster of multi-GPU servers. We suggest server-wise preloading
of essential vertex dependencies to reduce the low-bandwidth external server
communications. Second, we present expansion-aware sampling. Because shared
preloading alone has limitations because of the neighbor explosion,
expansion-aware sampling reduces vertex dependencies that span across server
boundaries. Third, we propose cooperative batching to create a unified
framework for full-graph and minibatch training. It significantly reduces
redundant memory usage in mini-batch training. From this, GraNNDis enables a
reasonable trade-off between full-graph and mini-batch training through
unification especially when the entire graph does not fit into the GPU memory.
With experiments conducted on a multi-server/multi-GPU cluster, we show that
GraNNDis provides superior speedup over the state-of-the-art distributed GNN
training frameworks
Learning and innovation: Exploitation and exploration trade-offs
a b s t r a c t a r t i c l e i n f o This paper examines the relationship between learning and innovation outcomes, focusing on the trade-off between exploitation and exploration in learning and innovation. The study identifies two types of learning and two outcomes of innovation. Exploitation and exploration in learning are inversely associated with innovation rates and impact. While exploitative, localized learning is positively associated with innovation rates, but negatively associated with impact, exploratory learning-by-experimentation shows the opposite relationship. The study examines panel data of 103 companies in the global pharmaceutical industry over a 7-year period in an empirical test of our hypotheses. Results support the existence of the exploitation and exploration trade-off
Association between thyroid hormones and the components of metabolic syndrome
BACKGROUND:
Thyroid hormones are known to have direct and indirect effects on metabolism. Individuals with metabolic syndrome, a disease that is growing in incidence at a rapid rate, are at higher risk for cardiovascular disease, diabetes, and cancer. The aim of this study was to identify whether significant correlations exist between thyroid hormone levels and components of the metabolic syndrome in the general population of Korea.
METHODS:
The data were collected from the sixth Korea National Health and Nutrition Examination Surveys from 2013 to 2015. A total of 1423 participants were tested for thyroid function. The analysis of variance and multiple linear regression were performed to analyze the relationship between thyroid hormone level and components of the metabolic syndrome.
RESULTS:
A positive association between free thyroxine and fasting glucose level was observed in patients with high free thyroxine levels (≥1.70 ng/dL, β = 15.992, p = < 0.0001), when compared with patients with normal-middle free thyroxine levels. Moreover, a negative association was observed between free thyroxine and triglyceride levels in patients with normal-high free thyroxine levels (β = - 21.145, p = 0.0054) and those with high free thyroxine levels (β = - 49.713, p = 0.0404).
CONCLUSION:
Free thyroxine shows a partially positive association with fasting glucose and a partially negative association with triglycerides in the Korean population. In patients with abnormal thyroid function, follow up tests for glucose levels and lipid profiling during treatment for thyroid dysfunction would be beneficial in terms of overlooking metabolic syndrome and to prevent related diseases
Genetic Association Analysis of Fasting and 1- and 2-Hour Glucose Tolerance Test Data Using a Generalized Index of Dissimilarity Measure for the Korean Population
Glucose tolerance tests have been devised to determine the speed of blood glucose clearance. Diabetes is often tested with the standard oral glucose tolerance test (OGTT), along with fasting glucose level. However, no single test may be sufficient for the diagnosis, and the World Health Organization (WHO)/International Diabetes Federation (IDF) has suggested composite criteria. Accordingly, a single multi-class trait was constructed with three of the fasting phenotypes and 1- and 2-hour OGTT phenotypes from the Korean Association Resource (KARE) project, and the genetic association was investigated. All of the 18 possible combinations made out of the 3 sets of classification for the individual phenotypes were taken into our analysis. These were possible due to a method that was recently developed by us for estimating genomic associations using a generalized index of dissimilarity. Eight single-nucleotide polymorphisms (SNPs) that were found to have the strongest main effect are reported with the corresponding genes. Four of them conform to previous reports, located in the CDKAL1 gene, while the other 4 SNPs are new findings. Two-order interacting SNP pairs of are also presented. One pair (rs2328549 and rs6486740) has a prominent association, where the two single-nucleotide polymorphism locations are CDKAL1 and GLT1D1. The latter has not been found to have a strong main effect. New findings may result from the proper construction and analysis of a composite trait
The antifungal activity and membrane-disruptive action of dioscin extracted from Dioscorea nipponica
AbstractDioscin is a kind of steroidal saponin isolated from the root bark of wild yam Dioscorea nipponica. We investigated the antifungal effect of dioscin against different fungal strains and its antifungal mechanism(s) in Candida albicans cells. Using the propidium iodide assay and calcein-leakage measurement, we confirmed that dioscin caused fungal membrane damage. Furthermore, we evaluated the ability of dioscin to disrupt the plasma membrane potential, using 3,3′-dipropylthiadicarbocyanine iodide [DiSC3(5)] and bis-(1,3-dibarbituric acid)-trimethine oxanol [DiBAC4(3)]. Cells stained with the dyes had a significant increase in fluorescent intensity after exposure to dioscin, indicating that dioscin has an effect on the membrane potential. To visualize the effect of dioscin on the cell membrane, we synthesized rhodamine-labeled giant unilamellar vesicles (GUVs) mimicking the outer leaflet of the plasma membrane of C. albicans. As seen in the result, the membrane disruptive action of dioscin caused morphological change and rhodamine leakage of the GUVs. In three-dimensional contour-plot analysis using flow cytometry, we observed a decrease in cell size, which is in agreement with our result from the GUV assay. These results suggest that dioscin exerts a considerable antifungal activity by disrupting the structure in membrane after invading into the fungal membrane, resulting in fungal cell death
Perceived Dangerousness Mediates Punitive Attitudes Toward Sex Offenders: Results From a Vignette Experiment
The current study used an experimental vignette (n = 1,093) to examine the effects of perpetrator sex and age, and victim sex and age, on simulated juror sentencing recommendations for individuals convicted of sexual offenses (ICSO). Path analyses were used to see if differences in punitive attitudes could be explained by perceptions of dangerousness participants attached to experimentally manipulated variables, as hypothesized by attribution theorists. Results show that participants consistently recommended longer sentences, higher fines, and indicated greater support for post-release sanctions for male offenders, older perpetrators, and for offenders who victimized younger adolescents. Path analysis demonstrated that perceptions of dangerousness partially mediated the relationship between experimentally manipulated predictor variables and recommended sentence length, providing partial support for attribution theory
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