Tau is the major microtubule associated protein (MAP) of a mature neuron. The other two neuronal MAPs are MAP1 and MAP2. An established function of MAPs is their interaction with tubulin and ...promotion of its assembly into microtubules and stabilization of the microtubule network. The microtubule assembly promoting activity of tau, a phosphoprotein, is regulated by its degree of phosphorylation. Normal adult human brain tau contains 2-3 moles phosphate/mole of tau protein. Hyperphosphorylation of tau depresses this biological activity of tau. In Alzheimer disease (AD) brain tau is ~three to four-fold more hyperphosphorylated than the normal adult brain tau and in this hyperphosphorylated state it is polymerized into paired helical filaments (PHF) admixed with straight filaments (SF) forming neurofibrillary tangles. Tau is transiently hyperphosphorylated during development and during anesthesia and hypothermia but not to the same state as in AD brain. The abnormally hyperphosphorylated tau in AD brain is distinguished from transiently hyperphosphorylated tau by its ability (1) to sequester normal tau, MAP1 and MAP2 and disrupt microtubules, and (2) to self-assemble into PHF/SF. The cytosolic abnormally hyperphosphorylated tau, because of oligomerization, unlike normal tau, is sedimentable and on self-assembly into PHF/SF, loses its ability to sequester normal MAPs. Some of the tau in AD brain is truncated which also promotes its self-assembly. Tau mutations found in frontotemporal dementia apparently promote its abnormal hyperphosphorylation. Thus, the AD abnormally hyperphosphorylated tau (1) is distinguishable from both normal and transiently hyperphosphorylated taus, and (2) is inhibitory when in a cytosolic/oligomeric state but not when it is self-assembled into PHF/SF. Inhibition of abnormal hyperphosphorylation of tau offers a promising therapeutic target for AD and related tauopathies.
We present improved germanium-based constraints on sub-GeV dark matter via dark matter-electron (χ-e) scattering using the 205.4 kg·day dataset from the CDEX-10 experiment. Using a novel calculation ...technique, we attain predicted χ-e scattering spectra observable in high-purity germanium detectors. In the heavy mediator scenario, our results achieve 3 orders of magnitude of improvement for m_{χ} larger than 80 MeV/c^{2} compared to previous germanium-based χ-e results. We also present the most stringent χ-e cross-section limit to date among experiments using solid-state detectors for m_{χ} larger than 90 MeV/c^{2} with heavy mediators and m_{χ} larger than 100 MeV/c^{2} with electric dipole coupling. The result proves the feasibility and demonstrates the vast potential of a new χ-e detection method with high-purity germanium detectors in ultralow radioactive background.
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An interplay between pairing and topological orders has been predicted to give rise to superconducting states supporting exotic emergent particles, such as Majorana particles obeying non-Abelian ...braid statistics. We consider a system of spin polarized electrons on a Hofstadter lattice with nearest-neighbor attractive interaction and solve the mean-field Bogoliubov-de Gennes equations in a self-consistent fashion, leading to gauge-invariant observables and a rich phase diagram as a function of the chemical potential, the magnetic field, and the interaction. As the strength of the attractive interaction is increased, the system first makes a transition from a quantum Hall phase to a skyrmion lattice phase that is fully gapped in the bulk but has topological chiral edge current, characterizing a topologically nontrivial state. This is followed by a vortex phase in which the vortices carrying Majorana modes form a lattice; the spectrum contains a low-energy Majorana band arising from the coupling between neighboring vortex-core Majorana modes but does not have chiral edge currents. For some parameters, a dimer vortex lattice occurs with no Majorana band. The experimental feasibility and the observable consequences of skyrmions as well as Majorana modes are indicated.
Two-dimensional (2D) superconducting systems are of great importance for exploring exotic quantum physics. The recent development of fabrication techniques has stimulated studies of high-quality ...single-crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here, we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity) in 4-monolayer (ML) to 6-ML crystalline Pb films grown on striped incommensurate Pb layers on Si(111) substrates by molecular beam epitaxy. An anomalously large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that, in superconducting heterostructures, the interface can induce Zeeman-type spin-orbit interactions and modulate the superconductivity.
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Suicidal behaviour is prevalent among adolescents and is a significant predictor of future suicide attempts (SAs) and suicide death. Data on the prevalence and epidemiological characteristics of ...suicidal behaviour in Chinese adolescents are limited. This study was aimed to examine the prevalence, characteristics and risk factors of suicidal behaviour, including suicidal thought (ST), suicide plan (SP) and SA, in a large sample of Chinese adolescents.
This report represents the first wave data of an ongoing longitudinal study, Shandong Adolescent Behavior and Health Cohort. Participants included 11 831 adolescent students from three counties of Shandong, China. The mean age of participants was 15.0 (s.d. = 1.5) and 51% were boys. In November-December 2015, participants completed a structured adolescent health questionnaire, including ST, SP and SA, characteristics of most recent SA, demographics, substance use, hopelessness, impulsivity and internalising and externalising behavioural problems.
The lifetime and last-year prevalence rates were 17.6 and 10.7% for ST in males, 23.5 and 14.7% for ST in females, 8.9 and 2.9% for SP in males, 10.7 and 3.8% for SP in females, 3.4 and 1.3% for SA in males, and 4.6 and 1.8% for SA in females, respectively. The mean age of first SA was 12-13 years. Stabbing/cutting was the most common method to attempt suicide. Approximately 24% of male attempters and 16% of female attempters were medically treated. More than 70% of attempters had no preparatory action. Female gender, smoking, drinking, internalising and externalising problems, hopelessness, suicidal history of friends and acquaintances, poor family economic status and poor parental relationship were all significantly associated with increased risk of suicidal behaviour.
Suicidal behaviour in Chinese adolescents is prevalent but less than that previously reported in Western peers. While females are more likely to attempt suicide, males are more likely to use lethal methods. Multiple child and family factors are associated with suicidal behaviour. These findings highlight the importance of early screening and intervention of suicidal behaviour in Chinese adolescents.
Abstract
In this paper, the multiwavelength data from radio to X-ray bands for 2709 blazars in the 4FGL-DR3 catalog are compiled to calculate their spectral energy distributions using a parabolic ...equation
log
(
ν
f
ν
)
=
P
1
log
ν
−
P
2
2
+
P
3
. Some important parameters including spectral curvature (
P
1
), synchrotron peak frequency (
P
2
,
log
ν
p
), and peak luminosity (
log
L
p
) are obtained. Based on those parameters, we discussed the classification of blazars using the “Bayesian classification” and investigated some mutual correlations. We came to the following results. (1) Based on the Bayesian classification of synchrotron peak frequencies, the 2709 blazars can be classified into three subclasses, i.e.,
log
(
ν
p
/
Hz
)
<
13.7
for low synchrotron peak blazars (LSPs),
13.7
<
log
(
ν
p
/
Hz
)
<
14.9
for intermediate synchrotron peak blazars (ISPs), and
log
(
ν
p
/
Hz
)
>
14.9
for high synchrotron peak blazars (HSPs), and there are 820 HSPs, 750 ISPs, and 1139 LSPs. (2) The
γ
-ray emission has the closest relationship with radio emission, followed by optical emission, while the weakest relationship is that with X-ray emission. The
γ
-ray luminosity is also correlated with the synchrotron peak luminosity. (3) There are strong positive correlations between the curvature (1/∣
P
1
∣) and the peak frequency (
log
ν
p
) for all subclasses (FSRQs, (high, intermediate, and low) BL Lacertae objects). For different subclasses, the correlation slopes are different, which implies that there are different acceleration mechanisms and emission processes for different subclasses of blazars.
Three-dimensional (3D) Dirac semimetals, which possess 3D linear dispersion in the electronic structure as a bulk analogue of graphene, have lately generated widespread interest in both materials ...science and condensed matter physics. Recently, crystalline Cd3As2 has been proposed and proved to be a 3D Dirac semimetal that can survive in the atmosphere. Here, by using point contact spectroscopy measurements, we observe exotic superconductivity around the point contact region on the surface of Cd3As2 crystals. The zero-bias conductance peak (ZBCP) and double conductance peaks (DCPs) symmetric around zero bias suggest p-wave-like unconventional superconductivity. Considering the topological properties of 3D Dirac semimetals, our findings may indicate that Cd3As2 crystals under certain conditions could be topological superconductors, which are predicted to support Majorana zero modes or gapless Majorana edge/surface modes in the boundary depending on the dimensionality of the material.
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We report a successful observation of pressure-induced superconductivity in a topological compound Bi 2 Te 3 with T c of ∼3 K between 3 to 6 GPa. The combined high-pressure structure investigations ...with synchrotron radiation indicated that the superconductivity occurred at the ambient phase without crystal structure phase transition. The Hall effects measurements indicated the hole-type carrier in the pressure-induced superconducting Bi 2 Te 3 single crystal. Consequently, the first-principles calculations based on the structural data obtained by the Rietveld refinement of X-ray diffraction patterns at high pressure showed that the electronic structure under pressure remained topologically nontrivial. The results suggested that topological superconductivity can be realized in Bi 2 Te 3 due to the proximity effect between superconducting bulk states and Dirac-type surface states. We also discuss the possibility that the bulk state could be a topological superconductor.
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In this paper, the spin and parity of the Zc(3900)± state are determined to be JP = 1+ with a statistical significance larger than 7σ over other quantum numbers in a partial wave analysis of the ...process e+e- → π+π-J/Ψ. We use a data sample of 1.92 fb-1 accumulated at $ \sqrt{s}=4.23 $ and 4.26 GeV with the BESIII experiment. When parametrizing the Zc(3900)± with a Flatté-like formula, we determine its pole mass Mpole = (3881.2±4.2stat ±52.7syst) MeV/c2 and pole width Γpole = (51.8± 4.6stat ± 36.0syst) MeV. Finally, we also measure cross sections for the process e+e- → Zc(3900)+π- + c.c. → J/Ψπ+π- and determine an upper limit at the 90% confidence level for the process e+e- → Zc(4020)+π- + c.c. → J/Ψ π+π-.
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