Abstract We study the diffusive dynamics of a system in a nonlinear velocity-dependent frictional environment within a continuous time random walk model. In this model, the motion is governed by a ...shear-thinning frictional force, − γ 0 v / 1 + ( v 2 / v c 2 ) μ ( 0 < μ ⩽ 1 ), where γ 0 represents the coefficient of static friction and µ is the scaling index. Through analytical and numerical results, we construct a diffusion phase diagram that encompasses different regimes upon variations in parameters γ 0 and µ : normal diffusion; superdiffusion; and hyperdiffusion. These transitions occur because the induced weaker friction enhances the diffusion. With a decrease in the scaling index, we find that the γ 0 -dependent exponent of diffusion converges towards the experimental findings for ultracold 87 Rb atoms because the strong effective friction arises. The discrepancies between the fractional Lévy kinetics and the experimental findings may be potentially reconciled. We believe that these findings are helpful for analyzing experimental observations of cold atoms diffusing in optical lattices.
The long-term pulmonary function and related physiological characteristics of COVID-19 survivors have not been studied in depth, thus many aspects are not understood.
COVID-19 survivors were ...recruited for high resolution computed tomography (HRCT) of the thorax, lung function and serum levels of SARS-CoV-2 IgG antibody tests 3 months after discharge. The relationship between the clinical characteristics and the pulmonary function or CT scores were investigated.
Fifty-five recovered patients participated in this study. SARS-CoV-2 infection related symptoms were detected in 35 of them and different degrees of radiological abnormalities were detected in 39 patients. Urea nitrogen concentration at admission was associated with the presence of CT abnormalities (P = 0.046, OR 7.149, 95% CI 1.038 to 49.216). Lung function abnormalities were detected in 14 patients and the measurement of D-dimer levels at admission may be useful for prediction of impaired diffusion defect (P = 0.031, OR 1.066, 95% CI 1.006 to 1.129). Of all the subjects, 47 of 55 patients tested positive for SARS-CoV-2 IgG in serum, among which the generation of Immunoglobulin G (IgG) antibody in female patients was stronger than male patients in infection rehabilitation phase.
Radiological and physiological abnormalities were still found in a considerable proportion of COVID-19 survivors without critical cases 3 months after discharge. Higher level of D-dimer on admission could effectively predict impaired DLCO after 3 months discharge. It is necessary to follow up the COVID-19 patients to appropriately manage any persistent or emerging long-term sequelae.
Key Scientific Research Projects of Henan Higher Education Institutions
Objective:
Little is known about the composition of middle cerebral artery (MCA) plaques and how they relate to clinical status. Using high‐resolution magnetic resonance imaging (HR‐MRI), we aimed to ...examine the occurrence of high signal on T1‐weighted fat‐suppressed images (HST1) of MCA plaques, which are highly suggestive of fresh or recent intraplaque hemorrhage.
Methods:
We retrospectively analyzed the HR‐MRI and clinical data of 107 adult patients with high‐grade (>70%) MCA stenosis. On HR‐MRI, HST1 within an MCA plaque was defined as an area with an intensity >150% of the signal of adjacent muscles. The relationship between HST1 and clinical presentations was analyzed.
Results:
A total of 109 stenotic MCAs (46 symptomatic and 63 asymptomatic) on 981 image slices were analyzed. HST1 was revealed on HR‐MRI in 11 vessels (10.1%, 9 symptomatic and 2 asymptomatic). The occurrence rate of HST1 between symptomatic and asymptomatic MCAs was significantly different (19.6% vs 3.2%, p = 0.01).
Interpretation:
HST1 within MCA plaque on HR‐MRI is associated with ipsilateral stroke. Our results provide new insight into the vascular biology of MCA atherosclerosis. Ann Neurol 2012;71:195–198
The oncogene c‐Myc is aberrantly expressed and plays a key role in malignant transformation and progression of hepatocellular carcinoma (HCC). Here, we report that c‐Myc is significantly up‐regulated ...by tumor necrosis factor receptor–associated factor 6 (TRAF6), an E3 ubiquitin ligase, in hepatocarcinogenesis. High TRAF6 expression in clinical HCC samples correlates with poor prognosis, and the loss of one copy of the Traf6 gene in Traf6+/– mice significantly impairs liver tumorigenesis. Mechanistically, TRAF6 first interacts with and ubiquitinates histone deacetylase 3 (HDAC3) with K63‐linked ubiquitin chains, which leads to the dissociation of HDAC3 from the c‐Myc promoter and subsequent acetylation of histone H3 at K9, thereby epigenetically enhancing the mRNA expression of c‐Myc. Second, the K63‐linked ubiquitination of HDAC3 impairs the HDAC3 interaction with c‐Myc and promotes c‐Myc protein acetylation, which thereby enhances c‐Myc protein stability by inhibiting carboxyl terminus of heat shock cognate 70‐kDa–interacting protein–mediated c‐Myc ubiquitination and degradation. Importantly, TRAF6/HDAC3/c‐Myc signaling is also primed in hepatitis B virus–transgenic mice, unveiling a critical role for a mechanism in inflammation–cancer transition. In clinical specimens, TRAF6 positively correlates with c‐Myc at both the mRNA and protein levels, and high TRAF6 and c‐Myc expression is associated with an unfavorable prognosis, suggesting that TRAF6 collaborates with c‐Myc to promote human hepatocarcinogenesis. Consistently, curbing c‐Myc expression by inhibition of TRAF6 activity with a TRAF6 inhibitor peptide or the silencing of c‐Myc by small interfering RNA significantly suppressed tumor growth in mice. Conclusion: These findings demonstrate the oncogenic potential of TRAF6 during hepatocarcinogenesis by modulating TRAF6/HDAC3/c‐Myc signaling, with potential implications for HCC therapy.
Structural modulations have been recently found to cause some unusual physical properties, such as superconductivity or charge density waves; however, thus‐induced nonlinear optical properties are ...rare. We report herein two unprecedented incommensurately modulated nonlinear optical sulfides exhibiting phase matching behavior, A2SnS5 (A=Ba, Sr), with the (3+1)D superspace groups P21212(00γ)00s or P21(α0γ)0, featuring different modulations of the Sn2S7∞ belts. Remarkably, Ba2SnS5 exhibits an excellent second harmonic generation (SHG) of 1.1 times that of the benchmark compound AgGaS2 at 1570 nm and a very large laser‐induced damage threshold (LIDT) of 8×AgGaS2. Theoretical studies revealed that the structural modulations increase the distortions of the Sn/S building units by about 44 or 25 % in A2SnS5 (A=Ba, Sr), respectively, and enhance significantly the SHG compared with α‐Ba2SnSe5 without modulation. Besides, despite the smaller Eg, the A2SnS5 samples exhibit higher LIDTs owing to their smaller thermal expansion anisotropies (Ba2SnS5 (1.51)<Sr2SnS5 (2.08)<AgGaS2 (2.97)).
Two incommensurately modulated nonlinear optical sulfides, Ba2SnS5 and Sr2SnS5, exhibit phase matching behavior and large laser‐induced damage thresholds. The second harmonic generation of Ba2SnS5 at 1570 nm is 1.1‐fold stronger than that of AgGaS2 as it benefits from the positional and occupational modulations.
Mechanistic target of rapamycin complex 1 (mTORC1) integrates diverse environmental signals to control cellular growth and organismal homeostasis. In response to nutrients, Rag GTPases recruit mTORC1 ...to the lysosome to be activated, but how Rags are regulated remains incompletely understood. Here, we show that Sestrins bind to the heterodimeric RagA/B-RagC/D GTPases, and function as guanine nucleotide dissociation inhibitors (GDIs) for RagA/B. Sestrin overexpression inhibits amino-acid-induced Rag guanine nucleotide exchange and mTORC1 translocation to the lysosome. Mutation of the conserved GDI motif creates a dominant-negative form of Sestrin that renders mTORC1 activation insensitive to amino acid deprivation, whereas a cell-permeable peptide containing the GDI motif inhibits mTORC1 signaling. Mice deficient in all Sestrins exhibit reduced postnatal survival associated with defective mTORC1 inactivation in multiple organs during neonatal fasting. These findings reveal a nonredundant mechanism by which the Sestrin family of GDIs regulates the nutrient-sensing Rag GTPases to control mTORC1 signaling.
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•Sestrins prevent amino-acid-induced mTORC1 recruitment to the lysosome•Sestrins are guanine nucleotide dissociation inhibitors for RagA and RagB•A cell-permeable peptide containing the GDI motif inhibits mTORC1 activation•Sestrin deficiency renders mTORC1 signaling insensitive to nutrient status in vivo
Sestrins inhibits GDP dissociation from Rags GTPases, thereby modulating the role of mTORC1 in nutrient sensing.
Non‐linear optical chalcogenides with a wide band gap (Eg) and excellent NLO properties are key materials for highly desirable multiwaveband tunable optical parametric oscillators (OPOs). We exploit ...the “electronic structure engineer bucket effect” to develop a novel dual‐waveband SrZnGeS4 with an ultrawide transparency window. It exhibits an asymmetric Fdd2 structure that consists of layers formed by corner‐sharing ZnGeS6 dimers. SrZnGeS4 is transparent from 0.30 to 23.6 μm, spanning the UV‐, vis‐, mid‐ and far‐IR spectral regions and has the widest Eg (3.63 eV) in the AeMIIMIVQ4 family to date. It exhibits phase matching, high SHG intensities (e.g., 11.0×KDP and 17.5×AGS under λinc=1450 and 950 nm, respectively), and a very high laser‐induced damage threshold (35×AGS). These results not only suggest bright prospects for high‐power laser applications but may also enable applications of the multiwaveband OPO system from the UV‐visible to far‐IR regions.
An electronic structure‐engineering “bucket effect” strategy produces a novel non‐linear optical compound SrZnGeS4 with unique dual‐waveband NLO properties, including a second harmonic generation of 0.9–17.5×AgGaS2 under 850–2100 nm incident laser wavelengths and a laser‐induced damage threshold of 35×AgGaS2.
Based on the geometry of the codimension-2 surface in general spherically symmetric spacetime, we give a quasi-local definition of a photon sphere as well as a photon surface. This new definition is ...the generalization of the one provided by Claudel, Virbhadra, and Ellis but without referencing any umbilical hypersurface in the spacetime. The new definition effectively excludes the photon surface in spacetime without gravity. The application of the definition to the Lemaître–Tolman–Bondi (LTB) model of gravitational collapse reduces to a second order differential equation problem. We find that the energy balance on the boundary of the dust ball can provide one of the appropriate boundary conditions to this equation. Based on this crucial investigation, we find an analytic photon surface solution in the Oppenheimer–Snyder (OS) model and reasonable numerical solutions for the marginally bounded collapse in the LTB model. Interestingly, in the OS model, we find that the time difference between the occurrence of the photon surface and the event horizon is mainly determined by the total mass of the system but not the size or the strength of the gravitational field of the system.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Brain organoids are self-assembled three-dimensional aggregates generated from pluripotent stem cells with cell types and cytoarchitectures that resemble the embryonic human brain. As such, they have ...emerged as novel model systems that can be used to investigate human brain development and disorders. Although brain organoids mimic many key features of early human brain development at molecular, cellular, structural and functional levels, some aspects of brain development, such as the formation of distinct cortical neuronal layers, gyrification, and the establishment of complex neuronal circuitry, are not fully recapitulated. Here, we summarize recent advances in the development of brain organoid methodologies and discuss their applications in disease modeling. In addition, we compare current organoid systems to the embryonic human brain, highlighting features that currently can and cannot be recapitulated, and discuss perspectives for advancing current brain organoid technologies to expand their applications.
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