In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy ...physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.
In response to various stress signals, which introduce infidelity into the processes of cell growth and division, p53 initiates cell-cycle arrest, apoptosis, or senescence to maintain fidelity ...throughout the cell cycle. Although these functions are traditionally thought of as the major functions of the p53 protein for tumor suppression, recent studies have revealed some additional novel functions of the p53 pathway. These include the down-regulation of two central cell-growth pathways, the IGF/AKT-1 and mTOR pathways, and the up-regulation of the activities of the endosomal compartment. The IGF-1/AKT and mTOR pathways are two evolutionarily conserved pathways that play critical roles in regulation of cell proliferation, survival, and energy metabolism. In response to stress, p53 transcribes a group of critical negative regulators in these two pathways, including IGF-BP3, PTEN, TSC2, AMPK beta1, and Sestrin1/2, which leads to the reduction in the activities of these two pathways. Furthermore, p53 transcribes several critical genes regulating the endosomal compartment, including TSAP6, Chmp4C, Caveolin-1, and DRAM, and increases exosome secretion, the rate of endosomal removal of growth factor receptors (e.g., EGFR) from cell surface, and enhances autophagy. These activities all function to slow down cell growth and division, conserve and recycle cellular resources, communicate with adjacent cells and dendritic cells of the immune system, and inform other tissues of the stress signals. This coordinated regulation of IGF-1/AKT/mTOR pathways and the endosomal compartment by the p53 pathway integrates the molecular, cellular, and systemic levels of activities and prevents the accumulations of errors in response to stress and restores cellular homeostasis after stress.
We investigate the thermodynamics of Schwarzschild–Tangherlini black hole in the context of the generalized uncertainty principle (GUP). The corrections to the Hawking temperature, entropy and the ...heat capacity are obtained via the modified Hamilton–Jacobi equation. These modifications show that the GUP changes the evolution of the Schwarzschild–Tangherlini black hole. Specially, the GUP effect becomes susceptible when the radius or mass of the black hole approaches the order of Planck scale, it stops radiating and leads to a black hole remnant. Meanwhile, the Planck scale remnant can be confirmed through the analysis of the heat capacity. Those phenomena imply that the GUP may give a way to solve the information paradox. Besides, we also investigate the possibilities to observe the black hole at the Large Hadron Collider (LHC), and the results demonstrate that the black hole cannot be produced in the recent LHC.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Direct laser-reduction of graphene oxide (GO), as a lithography-free approach, has been proven effective in manufacturing in-plane micro-supercapacitors (MSCs) with fast ion diffusion. However, the ...power density and the charge/discharge rate are still limited by the relatively low conductivity of electrodes. Here, we report a facile approach by exploiting femtolaser in situ reduction of the hydrated GO and chloroauric acid (HAuCl4) nanocomposite simultaneously, which incorporates both the patterning of rGO electrodes and the fabrication of Au current collectors in a single step. These flexible MSCs boast achievements of one-hundred fold increase in electrode conductivities of up to 1.1 106 S m-1, which provide superior rate capability (50% for the charging rate increase from 0.1 V s-1 to 100 V s-1), sufficiently high frequency responses (362 Hz, 2.76 ms time constant), and large specific capacitances of 0.77 mF cm-2 (17.2 F cm-3 for volumetric capacitance) at 1 V s-1, and 0.46 mF cm-2 (10.2 F cm-3) at 100 V s-1. The use of photo paper substrates enables the flexibility of this fabrication protocol. Moreover, proof-of-concept 3D MSCs are demonstrated with enhanced areal capacitance (up to 3.84 mF cm-2 at 1 V s-1) while keeping high rate capabilities. This prototype of all solid-state MSCs demonstrates the broad range of potentials of thin-film based energy storage device applications for flexible, portable, and wearable electronic devices that require a fast charge/discharge rate and high power density.
The South Atlantic Anomaly (SAA) refers to a region where the strength of the magnetic field is notably weaker compared to a dipole field. While previous studies have primarily focused on its effects ...on the inner radiation belt, this study investigates its impact on the aurora system. By analyzing 2 years' worth of data obtained by the Fengyun‐3E/ACMag instrument, we discover that magnetic fluctuations within the auroral oval are significantly weaker in the longitude sector corresponding to the SAA, as compared to those outside this area. This characteristic remains permanent and independent of seasons and geomagnetic activities. Additional investigation using Defense Meteorological Satellite Program/Special Sensor Ultraviolet Spectrographic Imager (DMSP/SSUSI) observations reveals a similar phenomenon in the auroral intensity. Therefore, our results demonstrate that the SAA substantially weakens the aurora system, shedding new light on the effects of magnetic anomalies on planetary auroras and magnetosphere‐ionosphere‐thermosphere coupling.
Plain Language Summary
The South Atlantic Anomaly (SAA) is a unique location on Earth where the magnetic field is weaker than normal. This region has drawn a lot of attention because its weakened magnetic field brings the inner Van Allen radiation belt unusually close to the Earth's surface, which poses a threat to satellites passing through it. Here, we uncovered another interesting aspect of the SAA: its impact on the aurora system. To investigate this, we first examined 2 years' worth of data from the ACMag instruments on the Fengyun‐3E satellite, which orbits the Earth at an altitude of 836 km in a dawn‐dusk, Sun‐synchronous orbit. Our findings reveal that the magnetic fluctuations within the southern auroral oval are significantly weaker in the region that aligns with the SAA. This weakening effect is consistently present, regardless of the season or the level of geomagnetic activity. To reinforce our results, we also analyzed auroral intensity from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instrument on the Defense Meteorological Satellite Program (DMSP) satellite, and it corroborated the same weakening trend in this data set. In conclusion, our observations demonstrate that the SAA has a substantial impact on weakening the aurora system. This discovery deepens our understanding of how magnetic anomalies can influence planetary auroras.
Key Points
The effects of the South Atlantic Anomaly (SAA) on the terrestrial aurora system are examined using multiple instruments
Observations reveal a substantial weakening of auroral magnetic fluctuations and auroral intensity in the SAA longitude sector
The results indicate considering magnetic anomalies like the SAA is essential for comprehensively understanding planetary aurora systems
Skin plays an important role in innate immune responses to bacterial infection, but its molecular mechanism remains unclear in fish. The transcriptional profiling of the skin immune response to ...Aeromonas hydrophila infection of the zebrafish, Danio rerio (Hamilton), was performed by Affymetrix microarray analysis. The results showed that 538 genes were differentially expressed, of which 388 genes were up‐regulated and 150 genes were down‐regulated. The expression patterns for 106 representative genes were observed to be up‐regulated in zebrafish skin at 24 and 36 h post‐infection, and gene expression changes were clearly greater at 36 h. Gene Ontology classification indicated that 222 genes were significantly associated with the skin immunity, including complement activation, acute‐phase response, stress response, chemotaxis and apoptosis. Further Kyoto Encyclopedia of Genes and Genomes analysis showed that the significant pathways included MAPK, p53, Wnt, TGF‐β, Notch, ErbB, JAK‐STAT, VEGF, mTOR and Calcium signalling in skin immune responses, and several genes (e.g. akt2l, frap1, nras, rac1, xiap) were found to be involved in signalling networks. Moreover, expression changes in nine selected genes were verified by real‐time qPCR analysis. This is the first known report on transcriptome analysis in the skin of zebrafish against the pathogen A. hydrophila.
An orthotropic adhesion model is proposed based on the bi-potential method to solve adhesive contact problems with orthotropic interface properties between hyperelastic bodies. The model proposes a ...straightforward description of interface adhesion with orthotropic adhesion stiffness, whose components are conveniently expressed according to the local coordinate system. Based on this description, a set of extended unilateral and tangential contact laws has been formulated. Furthermore, we use an element-wise scalar parameter
β
to characterize the strength of interface adhesive bonds, and the effects of damage. Therefore, complete cycles of bonding and de-bonding of adhesive links with the account for orthotropic interface effects can be modelled. The proposed model has been tested on cases involving both tangential and unilateral contact kinematics. The test cases allowed emergence of orthotropic interface effects between elastomer bodies involving hyperelasticity. Meanwhile, the model can be implemented with minimum effort, and provides inspiration for the modelling of adhesive interface effects in areas of applications such as biomechanics.
To develop a multivariable prediction model for preoperative differentiation of ganglioneuroma (GN) from schwannoma in mediastinum and retroperitoneum based on clinical data and enhanced computed ...tomography (CT).
This was a retrospective diagnostic study. Patients diagnosed with mediastinum or retroperitoneal GN or schwannoma at Zhongshan Hospital between July 2006 and March 2022 were divided into a training cohort and a validation cohort at a ratio of 7:3. Clinical information and CT features were collected. Histopathology was the reference standard for diagnosis. The model was developed using binary logistic regression. The predictive performance of the model was assessed using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA).
A total of 105 patients (47 men and 58 women; mean age of 41 ± 15 years) were enrolled. There were significant differences in symptoms (p=0.006), location (p=0.008), ratio of the craniocaudal diameter (CC) to the major axis on axial images (CC/M; p=0.025), ratio of the CC to the diameter on axial images (CC/D; p<0.001), density homogeneity (p=0.001), enhancement homogeneity (p<0.001), enhancement degree (p<0.001), venous phase CT attenuation value (V; p=0.011), and blood vessels changes (p=0.045) between GN and schwannoma. The area under the ROC curve (AUC) and accuracy in the validation cohort were 0.841 (95% confidence interval CI 0.672, 1.000) and 0.839 (95% CI: 0.674, 0.929), respectively. Calibration curves and DCA showed that the model was beneficial for patients.
The multivariable prediction model exhibited good predictive performance and may facilitate preoperative planning.
•Preoperative differentiation of ganglioneuroma from schwannoma remains challenging.•Clinical and CT features differs between ganglioneuroma and schwannoma.•The multivariable prediction model exhibits good predictive performance.
The Low-Profile Visualized Intraluminal Support (LVIS) stent is a new device recently introduced for the treatment of wide-neck intracranial aneurysms. This single-center study presents the authors' ...preliminary experience using the LVIS stent to treat saccular aneurysms with parent arteries smaller than 2.5 mm.
Aneurysms with a LVIS stent used in a small parent vessel (<2.5 mm in diameter) between October 2014 and April 2016 were included. Procedure-related complications, angiographic results, clinical outcomes, and midterm follow-up data were analyzed retrospectively.
A total of 22 patients was studied, including 5 ruptured and 17 unruptured aneurysms. Most of the aneurysms were located in the anterior circulation (90.9%). Stent placement in the parent arteries measuring 1.7-2.4 mm in diameter (mean, 2.1 mm) was successful in 100% of cases. Procedure-related complication developed in 1 patient (4.5%) who presented with aneurysm rupture. No permanent morbidity and mortality occurred. Immediate angiographic outcome showed complete occlusion in 8 aneurysms (36.4%), neck residual in 8 (36.4%), and residual aneurysm in 6 (27.3%). All patients underwent angiographic follow-up at a mean of 8.3 months, which revealed complete occlusion in 18 (81.8%) patients, neck remnant in 3 (13.6%), and residual sac in 1 (4.5%). No recanalization of the target aneurysm was observed. There was 1 case with asymptomatic in-stent stenosis.
Our preliminary results show that the deployment of LVIS stents in small vessels is feasible, safe, and effective in the midterm. Larger studies with long-term follow-up are needed to validate our promising results.
Atmospheric reactive nitrogen (N
r
) has been a cause of serious environmental pollution in China. Historically, China used too little N
r
in its agriculture to feed its population. However, with the ...rapid increase in N fertilizer use for food production and fossil fuel consumption for energy supply over the last four decades, increasing gaseous N
r
species (e.g. NH
3
and NO
x
) have been emitted to the atmosphere and then deposited as wet and dry deposition, with adverse impacts on air, water and soil quality as well as plant biodiversity and human health. This paper reviews the issues associated with this in a holistic way. The emissions, deposition, impacts, actions and regulations for the mitigation of atmospheric N
r
are discussed systematically. Both NH
3
and NO
x
make major contributions to environmental pollution but especially to the formation of secondary fine particulate matter (PM
2.5
), which impacts human health and light scattering (haze). In addition, atmospheric deposition of NH
3
and NO
x
causes adverse impacts on terrestrial and aquatic ecosystems due to acidification and eutrophication. Regulations and practices introduced by China that meet the urgent need to reduce N
r
emissions are explained and resulting effects on emissions are discussed. Recommendations for improving future N management for achieving ‘win-win’ outcomes for Chinese agricultural production and food supply, and human and environmental health, are described.
This article is part of a discussion meeting issue ‘Air quality, past present and future’.
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