On the Jets Induced by a Cavitation Bubble Near a Cylinder

The dynamics of cavitation bubbles in the vicinity of a solid cylinder or fibre are seen in water treatment, demolition and/or cleaning of composite materials, as well as bio-medical scenarios such as ultrasound-induced bubbles near the tubular structures in the body. When the bubble collapses near the surface, violent fluid jets may be generated. Understanding whether these jets occur and predicting their directions -- departing or approaching the solid surface -- is crucial for assessing their potential impact on the solid phase. However, the criteria for classifying the onset and directions of the jets created by cavitation near a curved surface of a cylinder have not been established. In this research, we present models to predict the occurrence and directions of the jet in such scenarios. The onset criteria and the direction(s) of the jets are dictated by the bubble stand-off distance and the cylinder diameter. Our models are validated by comprehensive experiments. The results not only predict the jetting behaviour but can serve as guidelines for designing and controlling the jets when a cavitation bubble collapses near a cylinder, whether for protective or destructive purposes

Multilevel Matrix Factor Model

Large-scale matrix data has been widely discovered and continuously studied in various fields recently. Considering the multi-level factor structure and utilizing the matrix structure, we propose a multilevel matrix factor model with both global and local factors. The global factors can affect all matrix times series, whereas the local factors are only allow to affect within each specific matrix time series. The estimation procedures can consistently estimate the factor loadings and determine the number of factors. We establish the asymptotic properties of the estimators. The simulation is presented to illustrate the performance of the proposed estimation method. We utilize the model to analyze eight indicators across 200 stocks from ten distinct industries, demonstrating the empirical utility of our proposed approach.Comment: 47 pages, 22 figure

Endothelial actin depolymerization mediates NADPH oxidase-superoxide production during flow reversal

Slow moving blood flow and changes in flow direction, e.g., negative wall shear stress, can cause increased superoxide (O2·−) production in vascular endothelial cells. The mechanism by which shear stress increases O2·− production, however, is not well established. We tested the hypothesis that actin depolymerization, which occurs during flow reversal, mediates O2·− production in vascular endothelial cells via NADPH oxidase, and more specifically, the subunit p47phox. Using a swine model, we created complete blood flow reversal in one carotid artery, while the contralateral vessel maintained forward blood flow as control. We measured actin depolymerization, NADPH oxidase activity, and reactive oxygen species (ROS) production in the presence of various inhibitors. Flow reversal was found to induce actin depolymerization and a 3.9 ± 1.0-fold increase in ROS production as compared with forward flow. NADPH oxidase activity was 1.4 ± 0.2 times higher in vessel segments subjected to reversed blood flow when measured by a direct enzyme assay. The NADPH oxidase subunits gp91phox (Nox2) and p47phox content in the vessels remained unchanged after 4 h of flow reversal. In contrast, p47phox phosphorylation was increased in vessels with reversed flow. The response caused by reversed flow was reduced by in vivo treatment with jasplakinolide, an actin stabilizer (only a 1.7 ± 0.3-fold increase). Apocynin (an antioxidant) prevented reversed flow-induced ROS production when the animals were treated in vivo. Cytochalasin D mimicked actin depolymerization in vitro and caused a 5.2 ± 3.0-fold increase in ROS production. These findings suggest that actin filaments play an important role in negative shear stress-induced ROS production by potentiating NADPH oxidase activity, and more specifically, the p47phox subunit in vascular endothelium

Similar operation template attack on RSA-CRT as a case study

A template attack, the most powerful side-channel attack methods, usually first builds the leakage profiles from a controlled profiling device, and then uses these profiles to recover the secret of the target device. It is based on the fact that the profiling device shares similar leakage characteristics with the target device. In this study, we focus on the similar operations in a single device and propose a new variant of the template attack, called the similar operation template attack (SOTA). SOTA builds the models on public variables (e.g., input/output) and recovers the values of the secret variables that leak similar to the public variables. SOTA’s advantage is that it can avoid the requirement of an additional profiling device. In this study, the proposed SOTA method is applied to a straightforward RSA-CRT implementation. Because the leakage is (almost) the same in similar operations, we reduce the security of RSA-CRT to a hidden multiplier problem (HMP) over GF(q), which can be solved byte-wise using our proposed heuristic algorithm. The effectiveness of our proposed method is verified as an entire prime recovery procedure in a practical leakage scenario

The influence of insecure attachment on undergraduates’ jealousy: the mediating effect of self-differentiation

BackgroundJealousy is a complex emotion and can be healthy or pathological, depending on the intensity and the degree of control. Excessive jealousy was characterized by anxiety, anger, and alienation in the insecure attachment relationship.ObjectiveTo explore how insecure attachment triggered this intense emotion, this study investigated the relationship between two insecure attachment dimensions and jealousy and explored the influence of self-differentiation on the relationship.MethodA total of 477 undergraduates participated in the study, and the Bringle self–report jealousy scale (BSJS), the relationship questionnaire (RQ), the intimate relationship experience questionnaire (ECR), and the revised edition of self–the differentiation questionnaire (DSR) were used.ResultThe results showed that: (1) attachment anxiety had a significant positive predictive effect on jealousy, but attachment avoidance had no significant positive predictive effect; (2) self-differentiation partially mediated the relationship between attachment anxiety and jealousy, but it has no significant mediating effect between attachment avoidance and jealousy.ConclusionThe results suggest that attachment anxiety was correlated with jealousy because it strengthened the intensity of anxiety and anger toward their attachment figures and became out of control through a lower level of self-differentiation, which has important implications for clinical intervention

Impact of fracturing liquid absorption on the production and water-block unlocking for shale gas reservoir

A large amount of liquid is pumped into the shale gas reservoir during hydraulic fracturing, and the fluid flowback ratio is usually low. However, field experience showed that the liquids did not cause severe damage to shale gas reservoir. It is urgent to clarify the water block unlocking mechanism of a shale gas reservoir. This work is to discuss the water block unlocking mechanism in shale gas reservoir. Based on the characteristic study of shale gas formation, the fracturing fluid absorption mechanism, absorption ability and impact on shale gas formation damage are systematically studied. Study shows that ultra-low water saturation, abundant micro- to nano- tubulars and a huge contact area are the control factors for strong fluid absorption ability of gas-shale. The strong water absorption capacity of the shale gas formation matrix is a key factor in removing water block. Organic matter also has an important influence on absorption ability and gas production. A conceptual evaluation criterion for water block unlocking is proposed based on core absorption capacity, original water saturation and fracture density. The shut-in after hydraulic fracturing is beneficial to gas production and can reduce water production for certain shale gas reservoir.Cited as: Shen, Y., Ge, H., Zhang, X., Chang, L., Liu, D., Liu, J. Impact of fracturing liquid absorption on the production and water-block unlocking for shale gas reservoir. Advances in Geo-Energy Research, 2018, 2(2): 163-172, doi: 10.26804/ager.2018.02.0