Geodynamic effects of subducted seamount at the Manila Trench: Insights from numerical modeling

Abstract We used numerical modeling to investigate the geodynamic effects of subducted seamounts at the Manila Trench. A series of numerical modeling experiments were conducted with variable parameters, including the activation volume (Vact) and cohesion (C), which influence lithospheric rheology, the plate convergence velocity, and the age of subducting slab. Modeling results indicate that varying the Vact and C within an appropriate range have limited effects on the geodynamic process of subduction. A lower Vact allows the slab to sink more easily and results in a steeper dip angle. A slab break-off is more likely to occur under subduction at depths of 100–300 km, while the existence of a seamount further promotes the break-off process. The convergence rate is a key parameter affecting the break-off timing and depth. In contrast, under subduction where subducted oceanic plate move faster upper plate, the model results exhibit non-break-off, steady subduction. Slab age is another factor controlling break-off, where break-off time extends with slab age. A subduction without seamount will cause a ~2 Myr delay in break-off timing. We suggest that the low-velocity zone under the Manila Trench at 17o N is the result of a break-off event due to subduction of the Zhenbei-Huangyan Seamount Chain. Further to the north, such as the location at 19o N, the absence of seamount and an older oceanic crust would favor a delay in break-off timing during subduction

一种太阳能驱动处理赤泥污水的绿色节能装置

Alumina production will produce a large amount of red mud wastewater every year, which will cause great harm to the surrounding environment. In this study, a solar evaporator using biochar as photothermal material for red mud wastewater treatment was designed. Driven by sunlight, the device can recover water from red mud wastewater and absorb harmful substances in wastewater. This study provides a new idea for green and energy saving treatment of red mud wastewater

Properties and Asteroseismological analysis of a new ZZ ceti discovered by TMTS

Tsinghua university-Ma Huateng Telescope for Survey (TMTS) aims to discover rapidly evolving transients by monitoring the northern sky. The TMTS catalog is cross-matched with the white dwarf (WD) catalog of Gaia EDR3, and light curves of more than a thousand WD candidates are obtained so far. Among them, the WD TMTS J23450729+5813146 (hereafter J2345) is one interesting common source. Based on the light curves from the TMTS and follow-up photometric observations, periods of 967.113 s, 973.734 s, 881.525 s, 843.458 s, 806.916 s and 678.273 s are identified. In addition, the TESS observations suggest a 3.39 h period but this can be attributed to the rotation of a comoving M dwarf located within 3". The spectroscopic observation indicates that this WD is DA type with Teff = 11778+/-617K,log g = 8.38+/-0.31,mass=0.84+/-0.20Msun and age=0.704+/-0.377 Gyrs. Asteroseismological analysis reveals a global best-fit solution of Teff =12110+/-10K and mass=0.760+/-0.005Msun,consistent with the spectral fitting results, and Oxygen and Carbon abundances in the core center are 0.73 and 0.27, respectively. The distance derived from the intrinsic luminosity given by asteroseismology is 93 parsec, which is in agreement with the distance of 98 parsec from Gaia DR3. Additionally, kinematic study shows that this WD is likely a thick disk star. The mass of its zero-age main-sequence mass is estimated to be 3.08 Msun and has a main-sequence plus cooling age of roughly 900 Myrs.Comment: 10 pages, 10 figures, accepted for publication in MNRA

Bathymetric Highs Control the Along-Strike Variations of the Manila Trench: 2D Numerical Modeling

The Manila Trench is located at the eastern boundary of the South China Sea (SCS). It develops through the subduction of the SCS beneath the Philippine Sea Plate (PSP) since the early Neogene, driven by the northwestern plate motion of the PSP. The northern segment of the Manila trench at around 18° N—21.5°N is characterized by an obvious eastward convex in the trench shape and abrupt changes of slab dip angle, whereas the southern segment of the Manila trench at around 15°N—18°N is featured by an almost straight NS-trending trench line and smooth subducting slab morphology. However, the cause for the along-strike variations along the Manila trench remains poorly understood. In this study, we use 2-D thermo-mechanical modeling to investigate how bathymetric highs embedded in the subducting slab affect the topography of overriding plate and the morphology of subducting plate. Three major factors of bathymetric highs are systematically examined: 1) the crustal properties, 2) the width, and 3) the thickness. Geodynamic results suggest that the most important factor controlling abrupt changes in dipping angle is the crustal properties of bathymetric highs. Also, reduction of crustal thickness and increasing the width of continental bathymetric highs favor the abrupt change of dipping angle, whereas thicker (≥25 km) bathymetric highs are more likely to be blocked in the subduction zone before slab break-off. According to our numerical modeling results, we suggest that dramatic changes in the dip angle in the northern Manila trench and the convex shape were caused by subduction of a large thin continental terrane, whereas the smooth morphology of subducting slab in the southern segment and straight trench were associated with normal oceanic subduction with small seamounts.ISSN:2296-646

A Novel Deep Learning Approach to 5G CSI/Geomagnetism/VIO Fused Indoor Localization

For positioning tasks of mobile robots in indoor environments, the emerging positioning technique based on visual inertial odometry (VIO) is heavily influenced by light and suffers from cumulative errors, which cannot meet the requirements of long-term navigation and positioning. In contrast, positioning techniques that rely on indoor signal sources such as 5G and geomagnetism can provide drift-free global positioning results, but their overall positioning accuracy is low. In order to obtain higher precision and more reliable positioning, this paper proposes a fused 5G/geomagnetism/VIO indoor localization method. Firstly, the error back propagation neural network (BPNN) model is used to fuse 5G and geomagnetic signals to obtain more reliable global positioning results; secondly, the conversion relationship from VIO local positioning results to the global coordinate system is established through the least squares principle; and finally, a fused 5G/geomagnetism/VIO localization system based on the error state extended Kalman filter (ES-EKF) is constructed. The experimental results show that the 5G/geomagnetism fusion localization method overcomes the problem of low accuracy of single sensor localization and can provide more accurate global localization results. Additionally, after fusing the local and global positioning results, the average positioning error of the mobile robot in the two scenarios is 0.61 m and 0.72 m. Compared with the VINS-mono algorithm, our approach improves the average positioning accuracy in indoor environments by 69.0% and 67.2%, respectively

A Novel Deep Learning Approach to 5G CSI/Geomagnetism/VIO Fused Indoor Localization

For positioning tasks of mobile robots in indoor environments, the emerging positioning technique based on visual inertial odometry (VIO) is heavily influenced by light and suffers from cumulative errors, which cannot meet the requirements of long-term navigation and positioning. In contrast, positioning techniques that rely on indoor signal sources such as 5G and geomagnetism can provide drift-free global positioning results, but their overall positioning accuracy is low. In order to obtain higher precision and more reliable positioning, this paper proposes a fused 5G/geomagnetism/VIO indoor localization method. Firstly, the error back propagation neural network (BPNN) model is used to fuse 5G and geomagnetic signals to obtain more reliable global positioning results; secondly, the conversion relationship from VIO local positioning results to the global coordinate system is established through the least squares principle; and finally, a fused 5G/geomagnetism/VIO localization system based on the error state extended Kalman filter (ES-EKF) is constructed. The experimental results show that the 5G/geomagnetism fusion localization method overcomes the problem of low accuracy of single sensor localization and can provide more accurate global localization results. Additionally, after fusing the local and global positioning results, the average positioning error of the mobile robot in the two scenarios is 0.61 m and 0.72 m. Compared with the VINS-mono algorithm, our approach improves the average positioning accuracy in indoor environments by 69.0% and 67.2%, respectively

Improved active power control of virtual synchronous generator for enhancing transient stability

Abstract Virtual synchronous generators (VSGs) are widely used as grid‐forming control converters in the inverter‐dominated power system. Similar to synchronous generators (SGs), there would also be transient instability of VSGs under certain conditions. In this paper, the transient dynamics of VSGs during gird faults are fully investigated based on the large‐signal model. It is revealed that the significant deteriorative of active power control loop (APCL) is the main factor on the transient stability of VSGs. Thus, for enhancing transient stability during grid faults, an integrator‐based feedback loop is introduced for APCL. Then, an enhanced active power control of VSGs is presented with transient stability enhancement during grid faults. Moreover, the impacts of different integral parameters on the transient stability of VSGs are studied. Finally, the validity of the transient stability enhancement of VSGs is demonstrated by the hardware‐in‐loop (HIL) results

Projectively enriched symmetry and topology in acoustic crystals

Symmetry plays a key role in modern physics, as manifested in the revolutionary topological classification of matter in the past decade. So far, we seem to have a complete theory of topological phases from internal symmetries as well as crystallographic symmetry groups. However, an intrinsic element, i.e., the gauge symmetry in physical systems, has been overlooked in the current framework. Here, we show that the algebraic structure of crystal symmetries can be projectively enriched due to the gauge symmetry, which subsequently gives rise to new topological physics never witnessed under ordinary symmetries. We demonstrate the idea by theoretical analysis, numerical simulation, and experimental realization of a topological acoustic lattice with projective translation symmetries under a Z_{2} gauge field, which exhibits unique features of rich topologies, including a single Dirac point, Möbius topological insulator, and graphenelike semimetal phases on a rectangular lattice. Our work reveals the impact when gauge and crystal symmetries meet together with topology and opens the door to a vast unexplored land of topological states by projective symmetries.Ministry of Education (MOE)Published versionH. X., Z. W., Z. C., L. Y., Y. X. F., and B. Z. acknowledge support from the Singapore Ministry of Education Academic Research Fund Tier 3 Grant No. MOE2016-T3-1-006 and Tier 2 Grant No. MOE2019-T2-2-085. Y.-X. H. and S. A. Y. acknowledge support from the Singapore Ministry of Education Academic Research Fund Tier 2 Grant No. MOE2019-T2-1-001. Y. X. Z. acknowledges support from National Natural Science Foundation of China (Grants No. 12161160315 and No. 12174181)

Kidney health in the COVID-19 pandemic: An umbrella review of meta-analyses and systematic reviews

BackgroundThis umbrella review aims to consolidate evidence from systematic reviews and meta-analyses investigating the impact of the coronavirus disease-2019 (COVID-19) on kidney health, and the associations between kidney diseases and clinical outcomes in COVID-19 patients.MethodsFive databases, namely, EMBASE, PubMed, Web of Science, the Cochrane Database of Systematic Reviews and Ovid Medline, were searched for meta-analyses and systematic reviews from January 1, 2020 to June 2, 2022. Two reviewers independently selected reviews, identified reviews for inclusion and extracted data. Disagreements were resolved by group discussions. Two reviewers independently assessed the methodological quality of all included reviews using ROBIS tool. A narrative synthesis was conducted. The characteristics and major findings of the included reviews are presented using tables and forest plots. The included meta-analyses were updated when necessary. The review protocol was prospectively registered in PROSPERO (CRD42021266300).ResultsA total of 103 reviews were identified. Using ROBIS, 30 reviews were rated as low risk of bias. Data from these 30 reviews were included in the narrative synthesis. Ten meta-analyses were updated by incorporating 119 newly available cohort studies. Hospitalized COVID-19 patients had a notable acute kidney injury (AKI) incidence of 27.17%. AKI was significantly associated with mortality (pooled OR: 5.24) and severe conditions in COVID-19 patients (OR: 14.94). The pooled prevalence of CKD in COVID-19 patients was 5.7%. Pre-existing CKD was associated with a higher risk of death (pooled OR: 2.21) and disease severity (pooled OR: 1.87). Kidney transplant recipients were susceptible to SARS-CoV-2 infection (incidence: 23 per 10,000 person-weeks) with a pooled mortality of 18%.ConclusionKidney disease such as CKD or recipients of kidney transplants were at increased risk of contracting COVID-19. Persons with COVID-19 also had a notable AKI incidence. AKI, the need for RRT, pre-existing CKD and a history of kidney transplantation are associated with adverse outcomes in COVID-19.Systematic review registrationwww.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021266300, identifier: CRD42021266300

Single-Cell Analysis Reveals Major Histocompatibility Complex II-Expressing Keratinocytes in Pressure Ulcers with Worse Healing Outcomes

Pressure ulcer (PU) is a chronic wound often seen in patients with spinal cord injury and other bed-bound individuals, particularly in the elderly population. Despite its association with high mortality, the pathophysiology of PU remains poorly understood. In this study, we compared single-cell transcriptomic profiles of human epidermal cells from PU wound edges with those from uninjured skin and acute wounds in healthy donors. We identified significant shifts in the cell composition and gene expression patterns in PU. In particular, we found that major histocompatibility complex class II-expressing keratinocytes were enriched in patients with worse healing outcomes. Furthermore, we showed that the IFN-gamma in PU-derived wound fluid could induce major histocompatibility complex II expression in keratinocytes and that these wound fluid-treated keratinocytes inhibited autologous T-cell activation. In line with this observation, we found that T cells from PUs enriched with major histocompatibility complex II+ keratinocytes produced fewer inflammatory cytokines. Overall, our study provides a high-resolution molecular map of human PU compared with that of acute wounds and intact skin, providing insights into PU pathology and the future development of tailored wound therapy