83 research outputs found
Real-space recipes for general topological crystalline states
Topological crystalline states are short-range entangled states jointly
protected by onsite and crystalline symmetries. While the non-interacting limit
of these states, e.g., the topological crystalline insulators, have been
intensively studied in band theory and have been experimentally discovered, the
classification and diagnosis of their strongly interacting counterparts are
relatively less well understood. Here we present a unified scheme for
constructing all topological crystalline states, bosonic and fermionic, free
and interacting, from real-space "building blocks" and "connectors". Building
blocks are finite-size pieces of lower dimensional topological states protected
by onsite symmetries alone, and connectors are "glue" that complete the open
edges shared by two or multiple pieces of building blocks. The resulted
assemblies are selected against two physical criteria we call the "no-open-edge
condition" and the "bubble equivalence", which, respectively, ensure that each
selected assembly is gapped in the bulk and cannot be deformed to a product
state. The scheme is then applied to obtaining the full classification of
bosonic topological crystalline states protected by several onsite symmetry
groups and each of the 17 wallpaper groups in two dimensions and 230 space
groups in three dimensions. We claim that our real-space recipes give the
complete set of topological crystalline states for bosons and fermions, and
prove the boson case analytically using a spectral sequence expansion of group
cohomology.Comment: 17+44 pages, 7+1 figures, 0+2 tables. The content is the same as the
published version, but arranged differentl
NQO1 targeting prodrug triggers innate sensing to overcome checkpoint blockade resistance
Lack of proper innate sensing inside tumor microenvironment (TME) limits T cell-targeted immunotherapy. NAD(P)H:quinone oxidoreductase 1 (NQO1) is highly enriched in multiple tumor types and has emerged as a promising target for direct tumor-killing. Here, we demonstrate that NQO1-targeting prodrug β-lapachone triggers tumor-selective innate sensing leading to T cell-dependent tumor control. β-Lapachone is catalyzed and bioactivated by NQO1 to generate ROS in NQO1high tumor cells triggering oxidative stress and release of the damage signals for innate sensing. β-Lapachone-induced high mobility group box 1 (HMGB1) release activates the host TLR4/MyD88/type I interferon pathway and Batf3 dendritic cell-dependent cross-priming to bridge innate and adaptive immune responses against the tumor. Furthermore, targeting NQO1 is very potent to trigger innate sensing for T cell re-activation to overcome checkpoint blockade resistance in well-established tumors. Our study reveals that targeting NQO1 potently triggers innate sensing within TME that synergizes with immunotherapy to overcome adaptive resistance
Speed Ripple Reduction of Direct-Drive PMSM Servo System at Low-Speed Operation Using Virtual Cogging Torque Control Method
This paper presents a virtual cogging torque (VCT) control method to reduce the speed ripple of direct-drive permanent magnet synchronous machine (DD-PMSM) servo system under low-speed conditions. Compared with other factors, at low speeds, the cogging torque is the main factor that deteriorates the drive performance, even induces speed oscillations. Especially in this paper, due to volume limitation, the cogging torque is designed larger than normal one in order to remove the need of brake. Based on the model of PMSM, the cause and effect of the cogging torque are analyzed. Inspired by the characteristic of cogging torque, the VCT control method is proposed and investigated to significantly reduce the speed ripple at low speeds. The main idea of this proposed control method is to produce a proper virtual cogging torque and continuously move the corresponding virtual stable equilibrium point to drive the rotor smoothly. In addition to the principle of this control method, its analysis and implementation are studied as well. Simulation and experimental results from the prototype demonstrate that the proposed control method is correct and valid, and it is simple and effective to smooth the speed at low-speed operations
Reactive Astrocytes in Glial Scar Attract Olfactory Ensheathing Cells Migration by Secreted TNF-α in Spinal Cord Lesion of Rat
BACKGROUND:After spinal cord injury (SCI), the formation of glial scar contributes to the failure of injured adult axons to regenerate past the lesion. Increasing evidence indicates that olfactory ensheathing cells (OECs) implanted into spinal cord are found to migrate into the lesion site and induce axons regeneration beyond glial scar and resumption of functions. However, little is known about the mechanisms of OECs migrating from injection site to glial scar/lesion site. METHODS AND FINDINGS:In the present study, we identified a link between OECs migration and reactive astrocytes in glial scar that was mediated by the tumor necrosis factor-alpha (TNF-alpha). Initially, the Boyden chamber migration assay showed that both glial scar tissue and reactive astrocyte-conditioned medium promoted OECs migration in vitro. Reactive astrocyte-derived TNF-alpha and its type 1 receptor TNFR1 expressed on OECs were identified to be responsible for the promoting effect on OECs migration. TNF-alpha-induced OECs migration was demonstrated depending on activation of the extracellular signal-regulated kinase (ERK) signaling cascades. Furthermore, TNF-alpha secreted by reactive astrocytes in glial scar was also showed to attract OECs migration in a spinal cord hemisection injury model of rat. CONCLUSIONS:These findings showed that TNF-alpha was released by reactive astrocytes in glial scar and attracted OECs migration by interacting with TNFR1 expressed on OECs via regulation of ERK signaling. This migration-attracting effect of reactive astrocytes on OECs may suggest a mechanism for guiding OECs migration into glial scar, which is crucial for OECs-mediated axons regrowth beyond the spinal cord lesion site
Rotor Position Tracking Control for Low Speed Operation of Direct-Drive PMSM Servo System
In this paper, a rotor position tracking control (RPTC) strategy is proposed to effectively reduce the speed fluctuation for a direct-drive permanent magnet synchronous motor (DD-PMSM) servo system operating at low speed with different torque disturbances. In this strategy, considering the derivative relationship between the rotor position and speed, a speed command is converted to a real-time rotor position trajectory, and then a position-current two-loop control with the RPTC controller is proposed based on the internal model method to smoothly track the rotor position. In addition, the parameter design of RPTC controller from the perspectives of robust stability and anti-disturbance capability is investigated as well. Comparative simulation and experimental results demonstrate that, at low speed, the proposed RPTC strategy has a good speed performance for both periodic and non-periodic torque disturbances. Moreover, it enjoys simple implementation for not requiring the precise speed feedback and specific torque disturbance information
Giant magnetic quantum oscillations in the thermal conductivity of TaAs: Indications of chiral zero sound
Charge transport of topological semimetals has been in the focus of intensive
investigations because of their non-trivial band topology. Heat transport of
these materials, on the other hand, is largely unexplored and remains elusive.
Here we report on an observation of unprecedented, giant magnetic quantum
oscillations of thermal conductivity in the prototypical Weyl semimetal TaAs.
The oscillations are antiphase with the quantum oscillating electronic density
of states of a Weyl pocket, and their amplitudes amount to two orders of
magnitude of the estimation based on the Wiedemann-Franz law. Our analyses show
that all the conventional heat-transport mechanisms through diffusions of
propagating electrons, phonons and electron-hole bipolar excitations, are far
inadequate to account for these phenomena. Taking further experimental facts
that the parallel field configuration favors much higher magneto-thermal
conductivity, we propose that the newly proposed chiral zero sound provides a
reasonable explanation to these exotic phenomena. More work focusing on other
topological semimetals along the same line is badly called for.Comment: 15 pages, 5 figure
AXL targeting restores PD-1 blockade sensitivity of STK11/LKB1 mutant NSCLC through expansion of TCF1+ CD8 T cells
Mutations in STK11/LKB1 in non-small cell lung cancer (NSCLC) are associated with poor patient responses to immune checkpoint blockade (ICB), and introduction of a Stk11/Lkb1 (L) mutation into murine lung adenocarcinomas driven by mutant Kras and Trp53 loss (KP) resulted in an ICB refractory syngeneic KPL tumor. Mechanistically this occurred because KPL mutant NSCLCs lacked TCF1-expressing CD8 T cells, a phenotype recapitulated in human STK11/LKB1 mutant NSCLCs. Systemic inhibition of Axl results in increased type I interferon secretion from dendritic cells that expanded tumor-associated TCF1+PD-1+CD8 T cells, restoring therapeutic response to PD-1 ICB in KPL tumors. This was observed in syngeneic immunocompetent mouse models and in humanized mice bearing STK11/LKB1 mutant NSCLC human tumor xenografts. NSCLC-affected individuals with identified STK11/LKB1 mutations receiving bemcentinib and pembrolizumab demonstrated objective clinical response to combination therapy. We conclude that AXL is a critical targetable driver of immune suppression in STK11/LKB1 mutant NSCLC.publishedVersio
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