413 research outputs found
ULTRAFAST DYNAMICS AND NONLINEAR OPTICAL PROPERTIES OF GRAPHENE OXIDES AND NOBLE METAL NANOPARTICLES
Ph.DDOCTOR OF PHILOSOPH
Modulating Scalable Gaussian Processes for Expressive Statistical Learning
For a learning task, Gaussian process (GP) is interested in learning the
statistical relationship between inputs and outputs, since it offers not only
the prediction mean but also the associated variability. The vanilla GP however
struggles to learn complicated distribution with the property of, e.g.,
heteroscedastic noise, multi-modality and non-stationarity, from massive data
due to the Gaussian marginal and the cubic complexity. To this end, this
article studies new scalable GP paradigms including the non-stationary
heteroscedastic GP, the mixture of GPs and the latent GP, which introduce
additional latent variables to modulate the outputs or inputs in order to learn
richer, non-Gaussian statistical representation. We further resort to different
variational inference strategies to arrive at analytical or tighter evidence
lower bounds (ELBOs) of the marginal likelihood for efficient and effective
model training. Extensive numerical experiments against state-of-the-art GP and
neural network (NN) counterparts on various tasks verify the superiority of
these scalable modulated GPs, especially the scalable latent GP, for learning
diverse data distributions.Comment: 31 pages, 9 figures, 4 tables, preprint under revie
Phosphatidylinositol 3-kinase inhibitor(LY294002) induces apoptosis of human nasopharyngeal carcinoma in vitro and in vivo
BACKGROUND: To evaluate whether PI3K/Akt pathway could effect on apoptosis and its mechanism in nasopharyngeal carcinoma cells. METHODS: The activation of the PI3K/Akt and its effect on CNE-2Z cells in vivo and in vitro was investigated by MTT assay, flow cytometry, western blot, ELISA, terminal deoxyribonucleotide transferase-mediated nick-end labeling assays (TUNEL), and immunohistochemical analyses, using PI3K inhibitor, LY294002. RESULTS: The results showed that LY294002 inhibited the phosphorylating of Akt (S473), cell proliferation, and induced apoptosis in CNE-2Z cells. However, our experiment results also demonstrated that apoptosis-induced LY294002 was directly regulated by caspase-9 activation pathway. CONCLUSION: These data suggested that PI3K inhibitor, LY294002, induced apoptosis by caspase-9 activation pathway and might be as a potentially useful target for therapeutic intervention in nasopharyngeal carcinoma patients
Electronic reconstruction at SrMnO3-LaMnO3 superlattice interfaces
We use resonant soft x-ray scattering to study electronic reconstruction at
the interface between the Mott insulator LaMnO3 and the "band" insulator
SrMnO3. Superlattices of these two insulators were shown previously to have
both ferromagnetism and metallic tendencies [Koida et al., Phys. Rev. B 66,
144418 (2002)]. By studying a judiciously chosen superlattice reflection we
show that the interface density of states exhibits a pronounced peak at the
Fermi level, similar to that predicted by Okamoto et al. [Phys. Rev. B 70,
241104(R) (2004)]. The intensity of this peak correlates with the conductivity
and magnetization, suggesting it is the driver of metallic behavior. Our study
demonstrates a general strategy for using RSXS to probe the electronic
properties of heterostructure interfaces.Comment: 4.2 pages, 4 figure
Tricriticality in generalized Schloegl models for autocatalysis: Lattice-gas realization with particle diffusion
We analyze lattice–gas reaction–diffusion models which include spontaneous annihilation, autocatalytic creation, and diffusion of particles, and which incorporate the particle creation mechanisms of both Schloegl’s first and second models. For fixed particle diffusion or hop rate, adjusting the relative strength of these creation mechanisms induces a crossover between continuous and discontinuous transitions to a “poisoned” vacuum state. Kinetic Monte Carlo simulations are performed to map out the corresponding tricritical line as a function of hop rate. An analysis is also provided of the tricritical “epidemic exponent” for the case of no hopping. The phase diagram is also recovered qualitatively by applying mean-field and pair-approximations to the exact hierarchical form of the master equation for these models
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