The 2008 Wenchuan earthquake triggered the largest number of landslides among the recent strong earthquake events around the world. The loose landslide materials were retained on steep terrains and ...deep gullies. In the period from 2008 to 2015, numerous debris flows occurred during rainstorms along the Provincial Road 303 (PR303) near the epicentre of the earthquake, causing serious damage to the reconstructed highway. Approximately 5.24×106m3 of debris-flow sediment was deposited shortly after the earthquake. This paper evaluates the evolution of the debris flows that occurred after the Wenchuan earthquake, which helps understand long-term landscape evolution and cascading effects in regions impacted by mega earthquakes. With the aid of a GIS platform combined with field investigations, we continuously tracked movements of the loose deposit materials in all the debris flow gullies along an 18km reach of PR303 and the characteristics of the regional debris flows during several storms in the past seven years. This paper presents five important aspects of the evolution of debris flows: (1) supply of debris flow materials; (2) triggering rainfall; (3) initiation mechanisms and types of debris flows; (4) runout characteristics; and (5) elevated riverbed due to the deposited materials from the debris flows. The hillslope soil deposits gradually evolved into channel deposits and the solid materials in the channels moved towards the ravine mouth. Accordingly, channelized debris flows became dominant gradually. Due to the decreasing source material volume and changes in debris flow characteristics, the triggering rainfall tends to increase from 30mmh−1 in 2008 to 64mmh−1 in 2013, and the runout distance tends to decrease over time. The runout materials blocked the river and elevated the riverbed by at least 30m in parts of the study area. The changes in the post-seismic debris flow activity can be categorized into three stages, i.e., active, unstable, and recession.
•The evolution of debris flows since the Wenchuan earthquake in 2008 is documented.•We tracked the landslide-debris movements in the epicentral area from 2008 to 2015.•The rainfall threshold just after the earthquake was one thirds of the pre-earthquake level.•Channelized flows became dominant as more hillslope deposits evolved into channel deposits.•Post-seismic debris flow activities are divided into active, unstable and recession stages.
► Effect of LiNO3 on the Li anode and cathode of Li/S battery is studied, respectively. ► LiNO3 participates in the formation of a stable passivation film on the Li anode surface. ► LiNO3 may be ...reduced irreversibly on the cathode, affecting Li/S battery performance. ► Discharge mechanism of Li/S battery is explained from the viewpoint of phase transition.
In this work we study the effect of LiNO3 on the Li anode and sulfur cathode, respectively, of Li/S battery by using a Li/Li symmetric cell and a liquid Li/Li2S9 cell. On the Li anode, LiNO3 participates in the formation of a stable passivation film, and the resulting passivation film grows infinitely with the consumption of LiNO3. The passivation film formed with LiNO3 is known to effectively suppress the redox shuttle of the dissolved lithium polysulfides on Li anode. On the cathode, LiNO3 undergoes a large and irreversible reduction starting at 1.6V in the first discharge, and the irreversible reduction disappears in the subsequent cycles. Moreover, the insoluble reduction products of LiNO3 on the cathode adversely affect the redox reversibility of sulfur cathode. These results indicate that both the Li anode and sulfur cathode consume LiNO3, and that the best benefit of LiNO3 to Li/S battery occurs at the potentials higher than 1.6V. By limiting the irreversible reduction of LiNO3 on the cathode, we have shown that the Li/S cell with a 0.2m LiNO3 as the co-salt can provide a stable capacity of ∼500mAhg−1.
Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts1-3. Recent observations of a Galactic FRB4-8 suggest that at least some FRBs originate from magnetars, but the origin ...of cosmological FRBs is still not settled. Here we report the detection of1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref.9). These observations show irregular short-time variation ofthe Faraday rotation measure (RM), which scrutinizes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (au; Earth-Sun distance) ofthe source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy10-12 show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.
Abstract
We report on analysis of observations of the bright transient X-ray pulsar Swift J0243.6+6124 obtained during its 2017-2018 giant outburst with Insight-HXMT, NuSTAR, and Swift observatories. ...We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disk to a radiation pressure dominated (RPD) state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to super-critical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars (ULPs), which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields.
Background and purpose
In‐hospital complications after stroke represent barriers to optimal recovery and are even potentially life‐threatening. Anemia is common in stroke patients and is related to ...poor outcome after stroke. Less is known, however, of the association of anemia with complications. We aimed to investigate the impact of anemia on a series of in‐hospital complications after ischemic stroke.
Methods
Consecutive patients with ischemic stroke within 7 days were included. Anemia on admission and its severity were defined according to World Health Organization criteria. Eight pre‐specified complications, such as pneumonia, gastrointestinal bleeding (GIB) and hemorrhagic transformation, were recorded during hospitalization.
Results
A total of 2647 patients were included. Anemia was present in 648 patients (24.5%), and 883 patients (33.4%) experienced at least one complication. Patients with anemia were more likely to experience one or more complications, pneumonia, GIB and thromboembolism (all P < 0.001) than patients without anemia. After adjustment for the confounders, patients with anemia had an adjusted odds ratio for at least one complication of 1.539 95% confidence interval (CI), 1.232–1.923, for pneumonia of 1.707 (95% CI, 1.345–2.167), for GIB of 2.245 (95% CI, 1.215–4.148) and for thromboembolism of 3.443 (95% CI, 1.668–7.108). The risk of at least one complication, pneumonia, GIB and thromboembolism increased with anemia severity (all P < 0.05). There was no significant association between anemia and urinary tract infection, hemorrhagic transformation, seizures and brain herniation.
Conclusion
Anemia is an independent predictor of in‐hospital complications following stroke, especially for pneumonia, GIB and thromboembolism. It remains to be studied whether prophylaxis and treatment of anemia would prevent in‐hospital complications.
We present X-ray timing results of the new black hole candidate MAXI J1535−571 during its 2017 outburst from Hard X-ray Modulation Telescope (Insight-HXMT) observations taken from 2017 September 6 to ...23. Following the definitions given by Belloni, we find that the source exhibits transitions from the low/hard state to the hard intermediate state, and eventually to the soft intermediate state. Quasi-periodic oscillations (QPOs) are found in the intermediate states, which suggest different types of QPOs. With the large effective area of Insight-HXMT at high energies, we are able to present the energy dependence of the QPO amplitude and centroid frequency up to 100 keV, which has rarely been explored by previous satellites. We also find that the phase lag at the type-C QPOs centroid frequency is negative (soft lag) and strongly correlated with the centroid frequency. Assuming a geometrical origin of type-C QPOs, the source is consistent with being a high-inclination system.
Magnetic topological phases of quantum matter are an emerging frontier in physics and material science. Along these lines, several kagome magnets have appeared as the most promising platforms. Here, ...we explore magnetic correlations in the kagome magnet Co
Sn
S
. Using muon spin-rotation, we present evidence for competing magnetic orders in the kagome lattice of this compound. Our results show that while the sample exhibits an out-of-plane ferromagnetic ground state, an in-plane antiferromagnetic state appears at temperatures above 90 K, eventually attaining a volume fraction of 80% around 170 K, before reaching a non-magnetic state. Strikingly, the reduction of the anomalous Hall conductivity (AHC) above 90 K linearly follows the disappearance of the volume fraction of the ferromagnetic state. We further show that the competition of these magnetic phases is tunable through applying either an external magnetic field or hydrostatic pressure. Our results taken together suggest the thermal and quantum tuning of Berry curvature induced AHC via external tuning of magnetic order.
Based on in situ and ground‐based observations, a new type of “polar cap hot patch” has been identified that is different from the classical polar cap enhanced density structure (cold patches). ...Comparing with the classical polar cap patches, which are transported from the dayside sunlit region with dense and cold plasma, the polar cap hot patches are associated with particle precipitations (therefore field‐aligned currents), ion upflows, and flow shears. The hot patches may have the same order of density enhancement as classical patches in the topside ionosphere, suggesting that the hot patches may be produced by transported photoionization plasma into flow channels. Within the flow channels, the hot patches have low‐energy particle precipitation and/or ion upflows associated with field‐aligned currents and flow shears. Corresponding Global Navigation Satellite System (GNSS) signal scintillation measurements indicate that hot patches may produce slightly stronger radio signal scintillation in the polar cap region than classical patches. A new type of polar cap patches, “polar cap hot patches,” is identified to differentiate enhanced density structures from classical patches. Hot patches are associated with particle precipitations, ion upflows, field‐aligned currents, and shear flows in the polar cap. Hot patches may lead to slightly stronger ionospheric scintillations of GNSS signals in the polar cap region than classical patches.
Key Points
A new type of polar cap patches, “polar cap hot patches,” is identified to differentiate enhanced density structures from classical patches
Hot patches are associated with particle precipitations, ion upflows, field‐aligned currents, and shear flows in the polar cap
Hot patches may lead to slightly stronger ionospheric scintillations of GNSS signals in the polar cap region than classical patches
3D-printing has been used for rapidly prototyping a low-cost and light-weight dielectric Fresnel zone plate lens. This lens was comprised of four dielectric zones and they were fabricated in one ...process with the tailored permittivities. Measurements show that this lens provides 7.3–12.8 dB gain enhancement over the frequency band from 8 to 12 GHz.
PDF
