4,996 research outputs found
Clustering Hidden Markov Models With Variational Bayesian Hierarchical EM.
The hidden Markov model (HMM) is a broadly applied generative model for representing time-series data, and clustering HMMs attract increased interest from machine learning researchers. However, the number of clusters ( K ) and the number of hidden states ( S ) for cluster centers are still difficult to determine. In this article, we propose a novel HMM-based clustering algorithm, the variational Bayesian hierarchical EM algorithm, which clusters HMMs through their densities and priors and simultaneously learns posteriors for the novel HMM cluster centers that compactly represent the structure of each cluster. The numbers K and S are automatically determined in two ways. First, we place a prior on the pair (K,S) and approximate their posterior probabilities, from which the values with the maximum posterior are selected. Second, some clusters and states are pruned out implicitly when no data samples are assigned to them, thereby leading to automatic selection of the model complexity. Experiments on synthetic and real data demonstrate that our algorithm performs better than using model selection techniques with maximum likelihood estimation
Effects of Ganoderma lucidum Spent Mushroom Substrate Extract on Milk and Serum Immunoglobulin Levels and Serum Antioxidant Capacity of Dairy Cows
Purpose: To investigate the effects of Ganoderma lucidum hot water extract (HWE) from spent mushroom substrate on milk and serum immunoglobulin levels and serum antioxidant capacity.Methods: Forty cows within the same parity and stage of lactation and with similar body weight were randomly divided into four groups of 10 cows each. The daily dietary dosage of HWE was 0, 33, 67, and 100 g for control and the three experimental groups EG1, EG2, and EG3, respectively. Serum antioxidant activity as well as milk and serum immunoglobulin levels were measured by enzyme-linked immunosorbent assay (ELISA).Results: After administration for 60 days, no significant differences in milk IgG, IgA, or IgM concentrations were detected among the experimental groups, but serum IgA concentration was significantly higher in EG1, EG2, and EG3 groups compared with control group (p < 0.01). Additionally, significant differences were detected in serum total antioxidant capacity (TAC) and mean serum TAC concentration among control, EG1, EG2, and EG3 groups (p < 0.05).Conclusion: The results suggest that when utilized as a feed additive, HWE may enhance immunity and antioxidant capacity in dairy cows, and subsequently improve milk quality.Keywords: Ganoderma lucidum, Spent mushroom substrate, Immunoglobulin, Antioxidant capacity, Dairy cow
You can't see what you can't see: Experimental evidence for how much relevant information may be missed due to Google's Web search personalisation
The influence of Web search personalisation on professional knowledge work is
an understudied area. Here we investigate how public sector officials
self-assess their dependency on the Google Web search engine, whether they are
aware of the potential impact of algorithmic biases on their ability to
retrieve all relevant information, and how much relevant information may
actually be missed due to Web search personalisation. We find that the majority
of participants in our experimental study are neither aware that there is a
potential problem nor do they have a strategy to mitigate the risk of missing
relevant information when performing online searches. Most significantly, we
provide empirical evidence that up to 20% of relevant information may be missed
due to Web search personalisation. This work has significant implications for
Web research by public sector professionals, who should be provided with
training about the potential algorithmic biases that may affect their judgments
and decision making, as well as clear guidelines how to minimise the risk of
missing relevant information.Comment: paper submitted to the 11th Intl. Conf. on Social Informatics;
revision corrects error in interpretation of parameter Psi/p in RBO resulting
from discrepancy between the documentation of the implementation in R
(https://rdrr.io/bioc/gespeR/man/rbo.html) and the original definition
(https://dl.acm.org/citation.cfm?id=1852106) as per 20/05/201
Probing the magnetic ground state of the molecular Dysprosium triangle
We present zero field muon spin lattice relaxation measurements of a
Dysprosium triangle molecular magnet. The local magnetic fields sensed by the
implanted muons indicate the coexistence of static and dynamic internal
magnetic fields below K. Bulk magnetization and heat capacity
measurements show no indication of magnetic ordering below this temperature. We
attribute the static fields to the slow relaxation of the magnetization in the
ground state of Dy3. The fluctuation time of the dynamic part of the field is
estimated to be ~0.55 s at low temperaturesComment: 5 pages, 5 figures, accepted for publication in Phys. Rev.
Approximation of conformal mappings by circle patterns
A circle pattern is a configuration of circles in the plane whose
combinatorics is given by a planar graph G such that to each vertex of G
corresponds a circle. If two vertices are connected by an edge in G, the
corresponding circles intersect with an intersection angle in .
Two sequences of circle patterns are employed to approximate a given
conformal map and its first derivative. For the domain of we use
embedded circle patterns where all circles have the same radius decreasing to 0
and which have uniformly bounded intersection angles. The image circle patterns
have the same combinatorics and intersection angles and are determined from
boundary conditions (radii or angles) according to the values of (
or ). For quasicrystallic circle patterns the convergence result is
strengthened to -convergence on compact subsets.Comment: 36 pages, 7 figure
Microfluidic-Generated Biopolymer Microparticles as Cargo Delivery Systems
Droplet microfluidics offers precise and simultaneous control of multiple fluids at microscale, which enables synthesis of novel microparticles with compositional and structural diversity in a controllable way. The morphology and functionality of generated microparticles can be well designed by modulating the hydrodynamic profile as well as geometric structures. The synergistic combination of droplet microfluidics with biodegradable materials makes it possible to encapsulate actives/drugs inside microparticles at high efficiency for drug delivery. The utilization of these microfluidic-generated microparticles with the characteristics of easy biodegradability and good biocompatibility in the field of drug delivery has made considerable progress in recent years. In this review, the commonly used structures of microchannel and methods to generate microparticles with droplet microfluidics are introduced. In addition, recent advances of biodegradable microparticles in the application of drug delivery are discussed and summarized with the focus on two kinds of biopolymers for preparing biodegradable microspheres, natural biopolymers, and synthetic biopolymers. Next, environment-sensing microencapsulation systems have been discussed because of their ability to release drug upon external stimulation, thereby allowing on-demand drug delivery. Finally, current challenges of utilizing microparticles in drug delivery are pointed out and some perspectives for the future direction in research and applications are provided
Controllable scattering of photons inside a one-dimensional resonator waveguide
We analyze coherent transport of photons, which propagate in a
one-dimensional coupled-resonator waveguide (CRW) and are scattered by a
controllable two-level system located inside the CRW. Our approach, which uses
discrete coordinates, unifies "low" and "high" energy effective theories for
single photon scattering. We show that the controllable two-level system can
behave as a quantum switch for the coherent transport of photons. This study
may inspire new electro-optical single-photon quantum devices. We also suggest
an experimental setup based on superconducting transmission line resonators and
qubitsComment: 4 pages, 5 figure
The development of grain storage scientific and technical research in China and relevant theory exploration
China is a major grain producer as well as a major grain consumer in the world. Grain storage was always highly regarded, and a long history and abundant management experience of grain storage and relevant theory has been accumulated in China. The development of grain storage scientific research in China in the twenty-first century had been summarized in this paper. Grain-storage safety theory and the establishment of Chinese grain storage ecological system is also discussed. New ideas on grain-storage research for the future are also introduced. Keywords: Grain, Storage, Theory, Chin
Confined Interfacial Monomicelle Assembly for Precisely Controlled Coating of Single-Layered Titania Mesopores
The development of core-shell structures has been in great demand recently owing to their integrated functionalities. However, the progress in reliable coating of porous semiconductors remains unproductive. Here, we have demonstrated a confined interfacial monomicelle assembly method for controlled coating of ordered single-layered mesoporous TiO2. The coating method can be well controlled with tunable coated layers, mesopore size, and switchable coated surfaces. The resulting mesoporous TiO2 exhibit excellent electrochemical properties as a sodium-ion anode, which is attributed to their unique mesostructures associated with accessible high surface area and ultrathin layers. Such accurately designed mesoporous core-shell nanostructures are expected to provide a useful platform to produce numerous delicate core-shell nanostructures with integrated functionalities and mesoporosities for potential applications, such as catalysts, sensors, energy storage, and energy conversion. - 2019 Elsevier Inc.Mesoporous core-shell nanostructures have recently been receiving extensive scientific interest; however, reliable approaches for coating mesoporous materials still remain exciting challenges, except for amorphous silica. We report, for the first time, a confined interfacial monomicelle assembly method for controlled coating of anatase TiO2 with single-layered ordered mesopores on diverse surfaces, opening up the area of coating ordered mesoporous crystalline materials that possess mesopores originating from self-assembled surfactant instead of accumulated nanocrystals. This facile and repeatable methodology relies on the solvent-confinement effect of glycerol during the assembly process and monomicelle hydrogel preformation by selective evaporation of double-solvent precursors. This assembly process shows precise controllability and great versatility, endowing the coated TiO2 layers with highly tunable thickness, mesopore size, and switchable coated surfaces. The ultrathin monolayered mesopores of such mesoporous TiO2 shells, in combination with their high surface area and highly crystalline nature, afford them excellent rate capability and superior cyclability for sodium-ion storage. - 2019 Elsevier Inc.We have demonstrated a confined interfacial monomicelle assembly approach for accurately coating ordered monolayered TiO2 mesopores on diverse surfaces. By regulating the synthetic conditions, the coated mesoporous TiO2 layers can be well controlled with desired thickness, mesopore size, and switchable coated surfaces. The resulting monolayered mesoporous TiO2 exhibit excellent sodium-storage properties. This unique mesoporous TiO2 coating strategy affords great potential in constructing multicomponent nanostructures with mesoporosities for advanced technologies. - 2019 Elsevier Inc.This work is supported by the State Key Basic Research Program of China ( 2017YFA0207303 ), the National Natural Science Foundation of China ( 21733003 ), the Shanghai Leading Academic Discipline Project ( B108 ), and the Science and Technology Commission of Shanghai Municipality ( 17JC1400100 ). K.L. acknowledges the financial support by the China Scholarship Council ( 201806100112 ). A.E. acknowledges Qatar University under GCC Co-Fund Program grant GCC-2017-001
Determination of the photodisintegration reaction rates involving charged particles: systematical calculations and proposed measurements based on Extreme Light Infrastructure - Nuclear Physics (ELI-NP)
Photodisintegration reaction rates involving charged particles are of
relevance to the p-process nucleosynthesis that aims at explaining the
production of the stable neutron-deficient nuclides heavier than iron. In this
study, the cross sections and astrophysical rates of (g,p) and (g,a) reactions
for about 3000 target nuclei with 10<Z<100 ranging from stable to proton
dripline nuclei are computed. To study the sensitivity of the calculations to
the optical model potentials (OMPs), both the phenomenological Woods-Saxon and
the microscopic folding OMPs are taken into account. The systematic comparisons
show that the reaction rates, especially for the (g,a) reaction, are
dramatically influenced by the OMPs. Thus the better determination of the OMP
is crucial to reduce the uncertainties of the photodisintegration reaction
rates involving charged particles. Meanwhile, a gamma-beam facility at ELI-NP
is being developed, which will open new opportunities to experimentally study
the photodisintegration reactions of astrophysics interest. Considering both
the important reactions identified by the nucleosynthesis studies and the
purpose of complementing the experimental results for the reactions involving
p-nuclei, the measurements of six (g,p) and eight (g,a) reactions based on the
gamma-beam facility at ELI-NP and the ELISSA detector for the charged particles
detection are proposed, and the GEANT4 simulations are correspondingly
performed. The minimum required energies of the gamma-beam to measure these
reactions are estimated. It is shown that the direct measurements of these
photonuclear reactions within the Gamow windows at T_9=2.5 for p-process are
fairly feasible and promising at ELI-NP. The expected experimental results will
be used to constrain the OMPs of the charged particles, which can eventually
reduce the uncertainties of the reaction rates for the p-process
nucleosynthesis.Comment: 14 pages, 8 figures, Phys. Rev. C accepte
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