The XYZ states revisited Yuan, Chang-Zheng
International journal of modern physics. A, Particles and fields, gravitation, cosmology,
07/2018, Letnik:
33, Številka:
21
Journal Article
Recenzirano
Odprti dostop
The BESIII and the LHCb became the leading experiments in the study of the exotic states after the Belle and BaBar experiments finished their data taking in the first decade of this century. We ...review the progress in the study of the XYZ states at BESIII and LHCb experiments with their unique data samples in
e
+
e
−
annihilation at center-of-mass energies of 3.8–4.6 GeV and in
p
p
collision at center-of-mass energies 7, 8, and 13 TeV, respectively. With these data samples, we have deepened our understanding of the most famous charmonium-like states
X
(
3
8
7
2
)
,
Y
(
4
2
6
0
)
,
Z
c
(
3
9
0
0
)
, and
Z
c
(
4
4
3
0
)
, as well as other similar states like the
Y
(
4
1
4
0
)
and
X
(
3
8
2
3
)
. We review the progress in the study of these states and also discuss perspectives at future experiments.
Objective: Artifact subspace reconstruction (ASR) is an automatic, online-capable, component-based method that can effectively remove transient or large-amplitude artifacts contaminating ...electroencephalographic (EEG) data. However, the effectiveness of ASR and the optimal choice of its parameter have not been systematically evaluated and reported, especially on actual EEG data. Methods: This paper systematically evaluates ASR on 20 EEG recordings taken during simulated driving experiments. Independent component analysis (ICA) and an independent component classifier are applied to separate artifacts from brain signals to quantitatively assess the effectiveness of the ASR. Results: ASR removes more eye and muscle components than brain components. Even though some eye and muscle components retain after ASR cleaning, the power of their temporal activities is reduced. Study results also showed that ASR cleaning improved the quality of a subsequent ICA decomposition. Conclusions: Empirical results show that the optimal ASR parameter is between 20 and 30, balancing between removing non-brain signals and retaining brain activities. Significance: With an appropriate choice of parameter, ASR can be a powerful and automatic artifact removal approach for offline data analysis or online real-time EEG applications such as clinical monitoring and brain-computer interfaces.
Abstract
Traditional CNN has problems with significant parameters and is difficult to deploy in a resource-constrained portable spectrometer for radionuclide identification. We propose a lightweight ...neural network model based on GhostNet to address these problems. First, the Ghost-CS module is built by adding the channel mixing operation in the Ghost module to enhance the information exchange between different channels; Secondly, using the ECA module reduces the noise information in the spectrum. The results showed that the algorithm maintains a high recognition accuracy while the number of model parameters is greatly reduced, making it easier to implement in portable spectrometers.
The large‐scale production of metal–air batteries, an appealing solution for next‐generation energy storage, requires low‐cost, earth‐abundant, and efficient oxygen electrode materials, yet insights ...into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen‐doped carbon nanotubes decorated by spinel CuCo2O4 quantum dots (CuCo2O4/N‐CNTs) is reported, outperforming the benchmark of state‐of‐the‐art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo2O4 and N‐doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu2+ and CuN) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo2O4/N‐CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all‐solid‐state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm−2 in liquid state, 1.86 W g−1 in all‐solid‐state), and long lifetime (48 h in liquid state, 9 h in all‐solid‐state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.
Advanced Cu Co bimetallic oxide quantum dots are decorated on nitrogen‐doped carbon nanotubes to serve as the bifunctional oxygen catalyst. A strong synergetic coupling in CuCo2O4/N‐CNTs is proposed, which provides advantaged local chemical environment and enriched catalytic sites. Benefiting from these features, CuCo2O4/N‐CNTs with reversible oxygen catalytic activity is capable of operating the new‐generation rechargeable zinc–air batteries.
A
bstract
We perform a systematical analysis of the
A
4
modular models with generalized CP for the masses and flavor mixing of quarks and leptons, and the most general form of the quark and lepton ...mass matrices is given. The CP invariance requires all couplings real in the chosen basis and thus the vacuum expectation value of the modulus
τ
uniquely breaks both the modular symmetry and CP symmetry. The phenomenologically viable models with minimal number of free parameters and the results of fit are presented. We find 20 models with 7 real free parameters that can accommodate the experimental data of lepton sector. We then apply
A
4
modular symmetry to the quark sector to explain quark masses and CKM mixing matrix, the minimal viable quark model is found to contain 10 free real parameters. Finally, we give two predictive quark-lepton unification models which use only 16 real free parameters to explain the flavor patterns of both quarks and leptons.
Covering: up to July 2019 Terpene synthases (TSs) are responsible for generating much of the structural diversity found in the superfamily of terpenoid natural products. These elegant enzymes mediate ...complex carbocation-based cyclization and rearrangement cascades with a variety of electron-rich linear and cyclic substrates. For decades, two main classes of TSs, divided by how they generate the reaction-triggering initial carbocation, have dominated the field of terpene enzymology. Recently, several novel and unconventional TSs that perform TS-like reactions but do not resemble canonical TSs in sequence or structure have been discovered. In this review, we identify 12 families of non-canonical TSs and examine their sequences, structures, functions, and proposed mechanisms. Nature provides a wide diversity of enzymes, including prenyltransferases, methyltransferases, P450s, and NAD+-dependent dehydrogenases, as well as completely new enzymes, that utilize distinctive reaction mechanisms for TS chemistry. These unique non-canonical TSs provide immense opportunities to understand how nature evolved different tools for terpene biosynthesis by structural and mechanistic characterization while affording new probes for the discovery of novel terpenoid natural products and gene clusters via genome mining. With every new discovery, the dualistic paradigm of TSs is contradicted and the field of terpene chemistry and enzymology continues to expand.
ZnO-ZnS core-shell composite rods were synthesized using a two-step facile hydrothermal methodology wherein different sulfidation durations were employed. The effects of sulfidation duration on the ...morphology and crystalline quality of ZnS shell layers on the surfaces of ZnO rods were investigated. A ZnS shell layer with visible granular features was obtained in the adequately controlled 3 h sulfidation process. A structural analysis demonstrated that the ZnS shell layers of ZnO-ZnS composite rods synthesized after 3 h sulfidation were in a well-defined crystalline cubic zinc blend phase. Moreover, optical properties revealed that these composite rods had a higher light-harvesting ability than those obtained after 1 and 2 h sulfidation. The density of surface crystal defects and the photoexcited charge separation efficiency of the composite rods were associated with changes in the microstructure of the synthesized ZnS shell layers. The optimal sulfidation duration of 3 h for the ZnO-ZnS composite rods resulted in the highest photocatalytic activity for the given photodegradation test conditions. The improved light harvesting and charge transport at the ZnO-ZnS heterointerface accounted for the enhanced photocatalytic activity of the ZnO-ZnS composite rods synthesized after 3 h sulfidation.
The quark model was formulated in 1964 to classify mesons as bound states made of a quark–antiquark pair, and baryons as bound states made of three quarks. For a long time all known mesons and ...baryons could be classified within this scheme. Quantum Chromodynamics (QCD), however, in principle also allows the existence of more complex structures, generically called exotic hadrons or simply exotics. These include four-quark hadrons (tetraquarks and hadronic molecules), five-quark hadrons (pentaquarks) and states with active gluonic degrees of freedom (hybrids), and even states of pure glue (glueballs). Exotic hadrons have been systematically searched for in numerous experiments for many years. Remarkably, in the past fifteen years, many new hadrons that do not exhibit the expected properties of ordinary (not exotic) hadrons have been discovered in the quarkonium spectrum. These hadrons are collectively known as XYZ states. Some of them, like the charged states, are undoubtedly exotic. Parallel to the experimental progress, the last decades have also witnessed an enormous theoretical effort to reach a theoretical understanding of the XYZ states. Theoretical approaches include not only phenomenological extensions of the quark model to exotics, but also modern non-relativistic effective field theories and lattice QCD calculations. The present work aims at reviewing the rapid progress in the field of exotic XYZ hadrons over the past few years both in experiments and theory. It concludes with a summary on future prospects and challenges.
Alzheimer's disease (AD) is the most common form of dementia in older adults. Currently, there is no cure for AD. The hallmark of AD is the accumulation of extracellular amyloid plaques composed of ...amyloid-β (Aβ) peptides (especially Aβ1-42) and neurofibrillary tangles, composed of hyperphosphorylated tau and accompanied by chronic neuroinflammation. Aβ peptides are derived from the amyloid precursor protein (APP). The oligomeric form of Aβ peptides is probably the most neurotoxic species; its accumulation eventually forms the insoluble and aggregated amyloid plaques. ApoE is the major apolipoprotein of the lipoprotein(s) present in the CNS. ApoE has three alleles, of which the Apoe4 allele constitutes the major risk factor for late-onset AD. Here we describe the complex relationship between ApoE4, oligomeric Aβ peptides, and cholesterol homeostasis. The review consists of four parts: 1) key elements involved in cellular cholesterol metabolism and regulation; 2) key elements involved in intracellular cholesterol trafficking; 3) links between ApoE4, Aβ peptides, and disturbance of cholesterol homeostasis in the CNS; 4) potential lipid-based therapeutic targets to treat AD. At the end, we recommend several research topics that we believe would help in better understanding the connection between cholesterol and AD for further investigations.
We report the first determination of the absolute branching fractions of the X(3872) decays by globally analyzing the measurements provided by the Belle, BABAR, BESIII, and LHCb experiments. The ...branching fractions of X(3872)→π+π−J/ψ and D*0D0+c.c. are found to be (...)% and (...)%, respectively. The branching fractions of the decays X(3872)→γJ/ψ, γψ(3686), ωJ/ψ, and π0χc1 are also determined. The global fit implies that the fraction of X(3872) decays which are not observed in experiments is (...)%, which indicates that there is still a lot of room for searching for new decay modes of the X(3872). With the branching fraction, we determine the production cross section of e+e−→γX(3872) at center-of-mass energy 4.226 GeV. (ProQuest: ... denotes formulae omitted.)
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