The Woodbury formula is an efficient tool in mathematics to calculate low‐rank perturbation problems and has been applied to improve the computational efficiency of nonlinear seismic response ...analysis (NSRA) of structures with local nonlinearity. Using the Woodbury formula for NSRA can avoid the time‐consuming recalculation and factorization of the large‐dimensional global stiffness matrix of a structure by only solving a small‐dimensional Schur complement system representing local nonlinearity per iteration. Because the dimension of the Schur complement matrix is determined by the inelastic degree of freedom (IDOF) number, which represents the scale of local nonlinear regions, a small IDOF number is helpful for achieving the high‐efficiency advantage of the Woodbury formula. However, when performing NSRA for large‐scale structures, the IDOF number is usually relatively large, which contradicts the efficiency requirement of the Woodbury formula. To solve this problem and extend the advantage of the Woodbury formula to the NSRA of large‐scale structures, this paper first proposes a two‐stage IDOF number reduction method by eliminating the IDOFs that have insignificant effects on the results, and consequently, a variant Woodbury formula is derived. Because only the principal component in the Schur complement matrix is retained, the dimension of this matrix and the cost for factorizing it can be reduced significantly without losing accuracy, thus greatly improving the efficiency of the proposed method. Moreover, to reduce the additional computational time introduced by the IDOF number reduction procedure and to further improve the computational performance of the proposed method, an OpenMP parallel computational strategy is incorporated. Finally, the validity of the proposed method is verified by implementing incremental dynamic analysis for a large‐scale reinforced concrete structure.
Cell‐matrix adhesions play essential roles in a variety of biological processes. Herein, we report a label‐free method to map cell‐matrix adhesions of single living cells on an electrode surface by ...electrochemiluminescence (ECL). An indium tin oxide electrode modified with a silica nanochannel membrane was used as the substrate electrode, at which the ECL generation from freely diffusing luminophores provided a distinct visual contrast between adhesion sites and noncontacted domains, thus selectively revealing the former in a label‐free manner. With this methodology, we studied the spatial distribution, as well as dynamic variation, of cell‐matrix adhesions and the adhesion strength at the subcellular level. Cell‐matrix adhesions of an advancing cell sheet were finally imaged to study the movement of cells in collective migration. A statistical analysis suggests that cells on the far side of leading edge also have the propensity to migrate and do not act as just passive followers.
Electrochemiluminescence (ECL) with surface sensitivity was demonstrated to reveal cell‐matrix adhesions of single cells cultured on nanoporous electrode surfaces, as well as their dynamic variation and strength. This approach was further used for imaging cell‐matrix adhesions of an advancing cell sheet to study the moving tendency of cells in collective migration.
Cell junctions are protein structures located at specific cell membrane domains that determine key processes in multicellular development. Here we report spatially selective imaging of cell junctions ...by electrochemiluminescence (ECL) microscopy. By regulating the concentrations of luminophore and/or co‐reactant, the thickness of ECL layer can be controlled to match with the spatial location of different cell junctions. At a low concentration of luminophore, ECL generation is confined to the electrode surface, thus revealing only cell–matrix adhesions at the bottom of cells. While at a high concentration of luminophore, the ECL layer can be remarkably extended by decreasing the co‐reactant concentration, thus allowing the sequential imaging of cell–matrix and cell–cell junctions at the bottom and near the apical surface of cells, respectively. This strategy not only provides new insights into the ECL mechanisms but also promises wide applications of ECL microscopy in bioimaging.
The thickness of electrochemiluminescence (ECL) layer can be modulated by rationally regulating the concentrations of luminophore and/or co‐reactant to match with the spatial location of different cell junctions, thus allowing the spatially selective ECL imaging of cell–matrix adhesions at the bottom and cell–cell junctions near the apical surface of cells.
Seeking geophysical explanations for the periodic ∼six-year oscillation (SYO) previously found in the Earth's length-of-day variation (ΔLOD), we analyze the global GPS displacement and geomagnetic ...data using the array processing technique of OSE (Optimal Sequence Estimation), and find clear evidences of the 6-yr signals which manifest as a westward rotary propagating wave of the sectoral spherical-harmonic pattern of degree-2 order-2 (Y22). Based on the period, the spatial pattern, and the amplitudes and the estimated phases that exhibit consistent synchronicity among the three datasets, we propose the following scenario: The mantle-inner core gravitational (MICG) coupling gives rise to a 6-yr axial torsional libration of the inner core controlled by the sectoral Y22 density anomalies, or the equatorial ellipticities, in the inner core and the (lower) mantle, the angular momentum exchange between which manifests as the SYO in ΔLOD. It forces into action a pressure wave-2 cyclic in 6 yr through the fluid outer core, which in turn produces the corresponding GPS and geomagnetic variations. Our findings provide insight into the dynamics of the deep Earth, and corroborate a positive density anomaly for the lower-mantle Large Low-Shear-Velocity Provinces.
•A 6 yr signal (SYO) is found in global GPS and geomagnetic records for the first time.•The SYO in ΔLOD, GPS and geomagnetic data has a high degree of consistent synchronicity.•MICG coupling is suggested to explain the SYO favoring a positive density anomaly for LLSVP.
Computationally predicting drug-target interactions is useful to select possible drug (or target) candidates for further biochemical verification. We focus on machine learning-based approaches, ...particularly similarity-based methods that use drug and target similarities, which show relationships among drugs and those among targets, respectively. These two similarities represent two emerging concepts, the chemical space and the genomic space. Typically, the methods combine these two types of similarities to generate models for predicting new drug-target interactions. This process is also closely related to a lot of work in pharmacogenomics or chemical biology that attempt to understand the relationships between the chemical and genomic spaces. This background makes the similarity-based approaches attractive and promising. This article reviews the similarity-based machine learning methods for predicting drug-target interactions, which are state-of-the-art and have aroused great interest in bioinformatics. We describe each of these methods briefly, and empirically compare these methods under a uniform experimental setting to explore their advantages and limitations.
Summary
Evaluating the inelastic seismic response of structures accurately is of great importance in earthquake engineering and generally requires refined simulation, which is a time‐consuming ...process. Because the material nonlinearity generally occurs in a small part of the whole structure, many researches focus on taking advantage of this characteristic to improve the computational efficiency and the inelasticity‐separated finite element method (IS‐FEM) proposed recently provide a generic finite element formulation for solving this kind of problems efficiently. Although the fiber beam‐column element is widely used for the simulation of reinforced concrete (RC) framed structures, the inelastic deformation is often detected in a large part of the numerical model under earthquake excitation so that it is hard to achieve high efficient computation when applying the IS‐FEM to the inelastic response analysis of RC fiber models directly. In this paper, a new numerical scheme for seismic response analysis of RC framed structures model by fiber beam‐column element is proposed based on the IS‐FEM. To implement the RC fiber model for use in IS‐FEM and improve the computational performance of proposed scheme, a method of identifying the local domains with severe section inelasticity level is proposed and a modified Kent‐Park concrete material model is developed. Because the Woodbury formula is adopted as the solver, the global stiffness matrix can keep unchanged throughout the analysis and the main computational effort is only invested on a small matrix representing local inelastic behavior. The numerical examples demonstrate the validity and efficiency of the proposed scheme.
The mantle anelasticity plays an important role in Earth's interior dynamics. Here we seek to determine the lower-mantle anelasticity through the solution of the complex Love numbers at the Chandler ...wobble period. The Love numbers h21, l21, δ21 and k21 are obtained in the frequency domain by dividing off the observed polar motion, or more specifically the pole tide potential, from the observed GPS 3-D displacement field and SG gravity variation. The latter signals are obtained through the array processing method of OSE (optimal sequence estimation) that results in greatly enhanced signals to be extracted from global array data. The resultant Love number estimates h21=0.6248(±5e−4)−0.013(±5e−3)i, l21=0.0904(±8e−4)−0.0008(±2e−3)i, δ21=1.156(±2e−3)−0.003(±1e−3)i and k21=0.3125(±2e−3)−0.0069(±3e−3)i are thus well-constrained in comparison to past estimates that vary considerably. They further lead to estimates of the corresponding mantle anelastic parameters fr and fi, which in turn determines, under the single-absorption band assumption, the dispersion exponent of α=0.21±0.02 with respect to the reference frequency of 5 mHz. We believe our estimate is robust and hence can better constrain the mantle anelasticity and attenuation models of the Earth interior.
•Optimal stacking method used to estimate degree-2 order-1 Love numbers from pole tide.•We obtain well-constrained estimates for h21, l21, δ21 and k21 at CW frequency.•We estimate the mantle anelasticity and associated material-dependent exponent α.
The shared aperture antenna is regarded as one of the promising approaches to support new frequencies with very efficient space utilization. To the best of the authors' knowledge, there are few ...shared aperture antennas that include both the sub-6 GHz antenna and the millimeter-wave (mm-wave) beam-steering array for broadside applications. In this article, a broadside sharing aperture technique is developed so that a 2 <inline-formula> <tex-math notation="LaTeX">\times4\,\,26 </tex-math></inline-formula> GHz beam-steering substrate-integrated DRA (SIDRA) array can be integrated into a 3.5 GHz bandwidth enhanced perforated patch antenna in a coplanar and aperture-shared way. The proposed solution benefits from several aspects. First, the 3.5 GHz antenna features a compact size as this part is built on the substrate (where the mm-wave SIDRA is constructed) with a high permittivity. Second, the mm-wave SIDRA is a 3-D-type device, and in the case of coplanar integration, its height can be freely adapted to the thickness of 3.5 GHz antenna without concerning the impact from surface waves as many 2-D-type antennas have to do. Third, the antenna can be implemented with the multi-layer printed circuit board (PCB) process, yielding a high integrity level. The dual-frequency antenna was designed, fabricated, and measured. The performances of the antenna are reported with reasonable agreement between the measured and simulated results observed.
As a crucial basic structure in aviation and aerospace field, axially moving cylindrical shells exhibit complex dynamic behavior. However, the nonlinear dynamics of axially moving cylindrical shells ...under multi-source excitation is hard to find in literature. Inspired by this, the current paper aims to predict the combined resonance behavior of axially moving cylindrical shells under coupled longitudinal and transverse excitations. Considering graphene platelets reinforced metal foams (GPLRMF) and Donnell's nonlinear thin shell theory, Hamilton principle is applied for formulating the motion equations. Subsequently, the method of varying amplitudes (MVA) is established to determine the vibration response for GPLRMF cylindrical shells subjected to coupled transverse and longitudinal excitations, where the jump, bifurcation as well as multiple stable solutions analysis are conducted. Through validation research, the accuracy of the current calculation method is verified. Numerical results reveal that unexpected internal stable/unstable loop may occur, and the internal stable/unstable loop whether or not exist, it depends on the values of key parameters including external excitation amplitude, initial phase angle and damping coefficient. Additionally, the bifurcation curves of combined resonance can be regulated and supported by parametric resonance. Furthermore, unlike internal resonance, the amplitude frequency response curves of combined resonance exhibit different multi-jump phenomena.
Oligodendrocytes (OLs) death after spinal cord injury (SCI) contributes to demyelination, even leading to a permanent neurological deficit. Besides apoptosis, our previous study demonstrated that OLs ...underwent receptor-interacting serine-threonine kinase 3(RIP3)/mixed lineage kinase domain-like protein (MLKL)-mediated necroptosis. Considering that necroptosis is always accompanied with pro-inflammatory response and quercetin has long been used as anti-inflammatory agent, in the present study we investigated whether quercetin could inhibit necroptosis of OLs and suppress the M1 macrophages/microglia-mediated immune response after SCI as well as the possible mechanism.
In this study, we applied quercetin, an important flavonoid component of various herbs, to treat rats with SCI and rats injected with saline were employed as the control group. Locomotor functional recovery was evaluated using Basso-Beattie-Bresnahan (BBB) scoring and rump-height Index (RHI) assay. In vivo, the necroptosis, apoptosis, and regeneration of OLs were detected by immunohistochemistry, 5'-bromo-2'-deoxyuridine (BrdU) incorporation. The loss of myelin and axons after SCI were evaluated by Luxol fast blue (LFB) staining, immunohistochemistry, and electron microscopic study. The polarization of macrophages/microglia after SCI and the underlying mechanisms were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry. In vitro, the ATP and reactive oxygen species (ROS) level examination, propidium iodide (PI) labeling, and Western blotting were used to analyze the necroptosis of cultured OLs, while the signaling pathways-mediated polarization of cultured macrophages/microglia was detected by qRT-PCR and Western blotting.
We demonstrated that quercetin treatment improved functional recovery in rats after SCI. We then found that quercetin significantly reduced necroptosis of OLs after SCI without influencing apoptosis and regeneration of OLs. Meanwhile, myelin loss and axon loss were also significantly reduced in quercetin-treated rats, as compared to SCI + saline control. Further, we revealed that quercetin could suppress macrophages/microglia polarized to M1 phenotype through inhibition of STAT1 and NF-κB pathway in vivo and in vitro, which contributes to the decreased necroptosis of OLs.
Quercetin treatment alleviated necroptosis of OLs partially by inhibiting M1 macrophages/microglia polarization after SCI. Our findings suggest that necroptosis of OLs may be a potential therapeutic target for clinical SCI.
PDF
