Artificial synapses can boost neuromorphic computing to overcome the inherent limitations of von Neumann architecture. As a promising memristor candidate, ferroelectric tunnel junctions (FTJ) enable ...the authors to successfully emulate spike‐timing‐dependent synapses. However, the nonlinear and asymmetric synaptic weight update under repeated presynaptic stimulation hampers neuromorphic computing by favoring the runaway of synaptic weights during learning. Here, the authors demonstrate an FTJ whose conductivity varies linearly and symmetrically by judiciously combining ferroelectric domain switching and oxygen vacancy migration. The artificial neural network based on this FTJ‐synapse achieves classification accuracy of 96.7% during supervised learning, which is the closest to the maximum theoretical value of 98% achieved to date. This artificial synapse also demonstrates stable unsupervised learning in a noisy environment for its well‐balanced spike‐timing‐dependent plasticity response. The novel concept of controlling ionic migration in ferroelectric materials paves the way toward highly reliable and reproducible supervised and unsupervised learning strategies.
By combining ferroelectric domain switching and oxygen vacancy migration, a ferroelectric tunnel junction artificial synapse with intrinsic nonlinearity as low as 0.13–0.17 and symmetric weight updating is developed, which greatly improved the classification accuracy of neural network hardware in supervised learning to 96.7% and enhanced robustness to noise during unsupervised learning.
Quantum spin Hall (QSH) effect is promising for achieving dissipationless transport devices which can be achieved only at extremely low temperature presently. The research for new large-gap QSH ...insulators is critical for their realistic applications at room temperature. Based on first-principles calculations, we propose a QSH insulator with a sizable bulk gap as large as ∼0.22 eV in stanene film functionalized with the organic molecule ethynyl (SnC2H), whose topological electronic properties are highly tunable by the external strain. This large-gap is mainly due to the result of the strong spin-orbit coupling related to the pxy orbitals at the Γ point of the honeycomb lattice, significantly different from that consisting of the pz orbital as in free-standing group IV ones. The topological characteristic of SnC2H film is confirmed by the Z2 topological order and an explicit demonstration of the topological helical Dirac type edge states. The SnC2H film on BN substrate is observed to support a nontrivial large-gap QSH, which harbors a Dirac cone lying within the band gap. Owing to their high structural stability, this two-dimensional large-gap QSH insulator is promising platforms for topological phenomena and new quantum devices operating at room temperature in spintronics.
RRM2 plays an important role in different malignant tumors, but there are few studies in breast cancer. Public databases were used to analyze the expression of RRM2 in breast cancer and its ...prognostic value.
A total of 2,509 breast cancer samples were downloaded from the METABRIC database. The relationship between RRM2 expression and clinical pathology was evaluated. Using the BCIP database and real-time-PCR, and western blotting, RRM2 mRNA and protein expression of RRM2 in breast cancer tissues and cell lines were evaluated. Univariate and multivariate analysis defined independent prognostic factors that affected the overall survival of patients with breast cancer. The Kaplan-Meier method was used to study the relationship between the high expression of RRM2 and overall survival and distant metastasis-free survival (DMFS) of breast cancer patients. Finally, We performed Gene Set Enrichment Analysis (GSEA) and obtained the relevant pathways associated with high expression of RRM2 potentially influencing breast cancer progression.
RRM2 expression was significantly correlated with age, tumor size, grade, menopausal status, molecular typing, ER, PR, and Her-2 of patients with breast cancer(P<0.05). Univariate and multivariate regression analysis showed that RRM2, the number of positive lymph nodes, ER, Her-2, tumor size, and tumor stage can be used as independent prognostic factors for overall survival of patients with breast cancer. Kaplan-Meier analysis showed that in patients with Luminal A and Normal like breast cancers and Stage1 and stage2 breast cancers, patients with high expression of RRM2 had worse overall survival and DMFS. The analysis of the GSEA pathway showed that RRM2 is mainly enriched in the ERBB signaling pathway and other pathways.
The high expression of RRM2 has a worse prognosis in patients with breast cancer with specific features. It can be used as a biomarker for the prognosis of breast cancer.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Knowledge about chemical functionalization is of fundamental importance to design novel two-dimensional topological insulators. Despite theoretical predictions of quantum spin Hall effect (QSH) ...insulator via chemical functionalization, it is quite challenging to obtain a high-quality sample, in which the toxicity is also an important factor that cannot be ignored. Herein, using first-principles calculations, we predict an intrinsic QSH effect in amidogen-functionalized Bi/Sb(111) films (SbNH2 and BiNH2), characterized by nontrivial Z 2 invariant and helical edge states. The bulk gaps derived from p x,y orbitals reaches up to 0.39 and 0.83 eV for SbNH2 and BiNH2 films, respectively. The topological properties are robust against strain engineering, electric field, and rotation angle of amidogen, accompanied with sizable bulk gaps. Besides, the topological phases are preserved with different arrangements of amidogen. The H-terminated SiC(111) is verified as a good candidate substrate for supporting the films without destroying their QSH effect. These results have substantial implications for theoretical and experimental studies of functionalized Bi/Sb films, which also provide a promising platform for realizing practical application in dissipationless transport devices at room temperature.
With the development of functional genomics studies, a mass of long non‐coding RNAs (LncRNA) were discovered from the human genome. Long non‐coding RNAs serve as pivotal regulators of genes that are ...able to generate LncRNA–binding protein complexes to modulate a great number of genes. Recently, the LncRNA urothelial carcinoma‐associated 1 (UCA1) has been revealed to be dysregulated, which plays a critical role in the development of a few cancers. However, the role of the biology and clinical significance of UCA1 in the tumorigenesis of oral squamous cell carcinoma (OSCC) remain unknown. We found that UCA1 expression levels were upregulated aberrantly in tongue squamous cell carcinoma tissues and associated with lymph node metastasis and TNM stage. We explored the expression, function, and molecular mechanism of LncRNA UCA1 in OSCC. In the present work, we revealed that UCA1 silencing suppressed proliferation and metastasis and induced apoptosis of OSCC cell lines in vitro and in vivo, which might be related to the activation level of the WNT/β‐catenin signaling pathway. Our research results emphasize the pivotal role of UCA1 in the oncogenesis of OSCC and reveal a novel LncRNA UCA1–β‐catenin–WNT signaling pathway regulatory network that could contribute to our understanding in the pathogenesis of OSCC and assist in the discovery of a viable LncRNA‐directed diagnostic and therapeutic strategy for this fatal disease.
Our data highlighted the pivotal role of UCA1 in the tumorigenesis of oral squamous cell carcinoma, and revealed a novel LncRNA UCA1‐β‐catenin‐Wnt signaling pathway regulatory network, which may contribute to understand the pathogenesis of oral squamous cell carcinoma.
Abstract Spin period distribution provides important clues to understand the formation of millisecond pulsars (MSPs). To uncover the intrinsic period distribution, we analyze three samples of radio ...MSPs in the Galactic field and globular clusters. The selection bias due to pulse broadening has been corrected but turns out to be negligible. We find that all the samples can be well described by a Weibull distribution of spin frequencies. Considering MSPs in the Galactic field or globular clusters and in isolation or binary systems, we find no significant difference in the spin distribution among these subpopulations. Based on the current known population of MSPs, we find that submillisecond pulsars are unlikely to be discovered by the Square Kilometre Array, although up to ∼10 discoveries of pulsars that spin faster than the current record holder of P = 1.4 ms are expected.
Abstract
Gravitational waves (GWs) from compact binary coalescences provide an independent probe of
the cosmic expansion history other than electromagnetic waves. In this work, we assume the binary
...black holes (BBHs) detected by LIGO-Virgo-KAGRA (LVK) collaborations are of primordial origin and
constrain the population parameters of primordial black holes (PBHs) and Hubble parameter
H
(
z
)
using 42 BBHs from third LVK GW transient catalog (GWTC-3). Three PBH mass models are
considered: lognormal, power-law, and critical collapse PBH mass functions. By performing a
hierarchical Bayesian population analysis, the Bayes factor strongly disfavors the power-law PBH
mass function against the other two in GWTC-3. The constraints on standard Λ CDM
cosmological parameters are rather weak and in agreement with current results. When combining the
multi-messenger standard siren measurement from GW170817, the Hubble constant
H
0
is constrained
to be 69
-8
+19
km s
-1
Mpc
-1
and 70
-8
+26
km s
-1
Mpc
-1
at 68% confidence for the lognormal and
critical collapse mass models, respectively. Furthermore, we consider a mixed ABH+PBH model, in
which we assume LVK BBHs can come from both the astrophysical black hole (ABH) and PBH
channels. We find that the ABH+PBH model can better describe the mass distribution in GWTC-3 than
any single ABH or PBH model, thus improving the precision to constrain the Hubble constant. With
the increased BBH events, the mixed ABH+PBH model provides a robust statistical inference for both
the population and cosmological parameters.
The favored progenitor model for Gamma-ray Bursts (GRBs) with Supernova (SN) association is the core collapse of massive stars. One possible outcome of such a collapse is a rapidly spinning, strongly ...magnetized neutron star ("magnetar"). We systematically analyze the multi-wavelength data of GRB/SN associations detected by several instruments before 2017 June. Twenty GRB/SN systems have been confirmed via direct spectroscopic evidence or a clear light curve bump, as well as some spectroscopic evidence resembling a GRB-SN. We derive/collect the basic physical parameters of the GRBs and the SNe, and look for correlations among these parameters. We find that the peak brightness, 56Ni mass, and explosion energy of SNe associated with GRBs are statistically higher than other Type Ib/c SNe. A statistically significant relation between the peak energy of GRBs and the peak brightness of their associated SNe is confirmed. No significant correlations are found between the GRB energies (either isotropic or beaming-corrected) and the supernova energy. We investigate the energy partition within these systems and find that the beaming-corrected GRB energy of most systems is smaller than the SN energy, with less than 30% of the total energy distributed in the relativistic jet. The total energy of the systems is typically smaller than the maximum available energy of a millisecond magnetar (2 × 1052 erg), especially if aspherical SN explosions are considered. The data are consistent with-although not proof of-the hypothesis that most, but not all, GRB/SN systems are powered by millisecond magnetars.
We performed first-principles simulation on the electronic structure and magnetic properties of two-dimensional hexagonal silicene, which was recently synthesized. The results show that the weak ...overlapping between 3p z orbitals of neighbor Si atoms leads to a very reactive surface, resulting in a more energetically stable semiconducting surface upon being fully hydrogenated. Half-hydrogenation breaks the extended π-bonding network of silicene, leaving the electrons in the unsaturated Si atoms localized and unpaired, and thus it exhibits ferromagnetic semiconducting behavior with a band gap of 0.95 eV. The long-range ferromagnetic coupling between Si atoms was also predicted, with a Curie temperature of about 300 K. These results demonstrated that hydrogenation is an efficient route to tune the electronic properties of silicene sheets.
PDF
