V2X communication facilitates information sharing between a vehicle and the infrastructure, pedestrians, devices, or any other entity that may affect the vehicle, which is known as a critical ...component in 5G that promises to realize the vision of connected and autonomous vehicles. Crowd sensing, a.k.a. collective perception, is one of the essential concepts of V2X networks, where vehicles share their information collected by local perception sensors about the environment for improving safety, saving energy, optimizing traffic, and so on. Although the operational aspects of V2X networks are being studied actively, its security aspect has received little attention. In this article, we discuss security issues that may pose serious threats to crowd sensing in V2X networks, and we focus on V2X-specific threats that are unique in V2X networks, e.g. platoon disruption and perception data falsification. We also discuss countermeasures against these threats and the technical challenges that must be overcome to implement such methods.
Background
Osteoporosis (OP) is a systemic metabolic skeletal disorder characterized by a decrease in bone mineral density (BMD) and an increase in the risk of fracture. The level of selenium (Se) in ...serum is associated with BMD. However, the relationship between dietary and total selenium intake and parameters such as osteoporosis and BMD is unclear. By conducting National Health and Nutritional Examination Surveys (NHANES), in this study, we assessed the association of Se intake with BMD and the risk of OP among general middle-aged and elderly people.
Methods
The data were collected from three cycles of NHANES 2009–2010, 2013–2014, and 2017–2020. Information on the dietary and supplementary Se intake was obtained from 24-h dietary recall interviews. Additionally, dual-energy X-ray absorptiometry (DXA) was performed to measure BMD, which was later transformed into T-scores; OP was diagnosed when the T-score was ≤ -2.5. We constructed a logistic regression model for the association between selenium intake and the risk of OP based on the estimated odds ratios (ORs) and the 95% confidence intervals (CIs). We also constructed a multivariable linear regression model to analyze the relationship between selenium intake and BMD.
Results
In this study, 3,250 individuals (average age: 60.01 ± 10.09 years; 51.88% females) participated. The incidence of OP was 9.35% (3.30% for males and 17.75% for females). In the logistic regression model adjusted for every interested covariate, a higher quartile of dietary Se intake (OR for quartile 4
vs
. quartile 1: 0.63; 95% CI: 0.41–0.96; P for trend = 0.027) was related to a lower risk of OP relative to the lowest quartile. The total selenium intake also exhibited a consistent trend (OR for quartile 4
vs
. quartile 1: 0.67; 95% CI: 0.44–1.01; P for trend = 0.049). The results of the adjusted multivariate linear regression model showed that the participants with the highest quartile of dietary Se intake (Q4) had higher BMD in the total femur (β = 0.069, P = 0.001; P for trend = 0.001), femoral neck (β = 0.064, P = 0.001; P for trend = 0.001), and total spine (β = 0.030, P = 0.136; P for trend = 0.064) compared to those in quintile 1 (Q1). A similar trend of associations was observed for the total selenium intake with BMD, which was more prominent among females, as determined by the subgroup analysis.
Conclusion
In this study, the dietary intake and total intake of selenium were positively associated with BMD, whereas they were negatively associated with the risk of OP among adults in the US. Further studies are required to verify our results and elucidate the associated biological mechanism.
Damage to a belt conveyor idler will increase the downtime and maintenance cost, so it is very important to diagnose its fault. At present, the fault diagnosis of the idler of a belt conveyor is ...mostly based on vibration and temperature signal. However, contact fault diagnosis approaches are severely limited when sensors are inconvenient to install or when vibration and temperature signals cannot be returned. In this special case, the non-contact fault diagnosis method, represented by measuring acoustic signals, becomes a necessary means. To effectively extract mechanical state information from sound signals of belt conveyors and identify typical mechanical faults, we propose a fault detection method based on sample center distance weighted (support vector data description (SVDD)) and multi-frame fusion (Mel-frequency cepstral coefficient (MFCC)) features. Aiming at the disadvantage that single frame MFCC features and traditional SVDD are susceptible to noise, multi-frame fusion MFCC optimization features are used as samples, and the weighted SVDD model based on sample center distance is used for fault detection. Finally, the overall recognition accuracy of the experiment is greatly improved. It is proved that MFCC features of multi-frame fusion sound signal and weighted SVDD fault detection based on sample center distance can effectively determine whether there is a fault in the of belt conveyor idler.
Abstract Rainfall-induced landslides are a common geological hazard. Analyzing this problem necessitates the use of the unsaturated soil theory, with the soil-water characteristic curve (SWCC) being ...a crucial component. Most existing unsaturated soil seepage models are established based on the static soil-water characteristic curve model. However, the dynamic capillary pressure has been observed in experiments conducted in previous studies. In this study, experiments were performed to explore the dynamic impact of the SWCC. The influence of different infiltration rates was studied, and a rate-dependent SWCC model under dynamic conditions was established. The model was validated through experiments. The behavior of an unsaturated soil slope under different rainfall intensities was analyzed based on the equivalent model. The equation for the slope safety factor was then derived using the Bishop method. The slope safety factors based on both the rate-independent and rate-dependent SWCC models were compared. The results indicated that the safety factor continuously decreased with increasing rainfall intensity. The dynamic effect reduced the safety factor, making the slope more susceptible to instability.
Heavy metals in urban dust can enter the human body through a variety of ways, thus endangering human health. Understanding the bioaccessibility of heavy metals in urban dust is a key to its risk ...assessment. After the G20 summit in 2016, Hangzhou city has received much attention, including its environmental health risk. The surface dust collected from three different functional areas in Hangzhou were subjected to the in vitro physiologically based extraction test (PBET) to measure the bioaccessibility of Pb and Cd. In terms of spatial variation, the distribution of Pb bioaccessibility was in the order of residential areas > city parks > main roads > the Botanic Garden, while for Cd ordered in city parks > residential areas > main roads > the Botanic Garden. For temporal variation, the bioaccessibility of Pb was higher in autumn and winter, and the bioaccessibility of Cd was higher in spring and autumn. Based on multiple linear statistical analysis, the relationship between the spatial and temporal distribution differences of the bioaccessibility of Pb and Cd in the city and the main components was discussed. Meanwhile, the non-carcinogenic hazard quotients of Pb and the carcinogenic risk of Cd were calculated and showed no harm to human health, except the total Pb in the surface dust with a high non-carcinogenic risk for infants. Urban dust in Hangzhou city has a slight pollution and health risk from Pb. Currently, controlling and reducing the city’s Pb emission is the key to maintain Hangzhou city’s air quality and matching with its international tourism city.
Cadherin is a homophilic, Ca2+-dependent cell adhesion glycoprotein that mediates cell-cell adhesion. Among them, Cadherin-11 (CDH11), as a classical cadherin, participates in and influences many ...crucial aspects of human growth and development. Furthermore, The involvement of CDH11 has been identified in an increasing number of diseases, primarily including various tumorous diseases, fibrotic diseases, autoimmune diseases, neurodevelopmental disorders, and more. In various tumorous diseases, CDH11 acts not only as a tumor suppressor but can also promote migration and invasion of certain tumors through various mechanisms. Likewise, in non-tumorous diseases, CDH11 remains a pivotal factor in disease progression. In this context, we summarize the specific functionalities and mechanisms of CDH11 in various diseases, aiming to gain a more comprehensive understanding of the potential value of CDH11 in disease diagnosis and treatment. This endeavor seeks to provide more effective diagnostic and therapeutic strategies for clinical management across diverse diseases.
Taking a suspension bridge of (84+84+1092+84+84) m high-speed railway as an example, a nonlinear dynamic simulation model of long-span suspension bridge-tracks system is established. The seismic ...response characteristics of CWR system of railway suspension bridge under the action of multi-dimensional seismic waves are analyzed. The effects of design parameters such as initial temperature load mode and viscous damper on the seismic response of the system are discussed. Calculation results showed that the longitudinal seismic excitation has great influence on the steel rail stress on the adjacent bridges on both sides and the longitudinal shear force at the pier bottom, and the transverse seismic excitation has great influence on the steel rail stress on the main truss of the suspension bridge, the vertical seismic excitation has a great influence on the internal forces of the main cable and sling; the initial temperature load has a significant influence on the internal forces of the main cable and sling; by reasonably setting the damping coefficient and speed index of the viscous damper, it can effectively reduce the displacement at the end of the main tower pier beam and the bending moment at the bottom of the pier.
Unmanned aerial vehicles (UAVs) at low altitude flight may significantly degrade their performance and the safety under wind disturbances and incorrect operations. This paper presents a robust ...control strategy for UAVs to achieve good performance of low altitude flight and disturbance rejection. First, a novel second-order hexacopter dynamics is established and the position tracking is translated to the altitude and the rotational angle tracking problem. An integrated control scheme is created to deal with the challenges faced by hexacopter at low altitude flight, in which the influence of near-ground threshold distance and the desired roll, pitch, and yaw are analyzed. Moreover, an improved flying altitude planner and an attitude planner for low altitude conditions are designed respectively to avoid the overturning risk due to the big reaction torque and external disturbances. Second, a sliding-mode-based altitude tracking controller and an attitude tracking controller are designed to reduce the tracking errors and improve the robustness of the system. Finally, the proposed control scheme is tested on simulation and experiment platforms of multi-rotor UAV to show the feasibility and accurate trajectory tracking at low altitude flight.
The effects of fulvic acid (FA) on heavy metal bioaccumulation by algae have been extensively studied, but the quantitative description on its adsorption behavior is not elaborately illustrated. In ...the study, the two-step adsorption model is firstly proposed to describe the adsorption of Pb by algae in the presence of FA (R2 > 0.984), which is characterized with two-plateaus in the biosorption curves. The first plateau in the curve represents a monolayer adsorption process of free Pb2+; while the second reveals a multilayer adsorption process of Pb-FA binding to those adsorbed Pb by algae, and the bonding material was called as ternary complex of algae-Pb-(FA-Pb). The formation of the ternary complex caused a sharp increase of the amount of adsorbed Pb by algae which was measured by an atomic absorption spectrophotometry, and a decrease of the toxicity of Pb to algae verified with SEM and TEM images. The ternary phase diagram showed FA could participate in the formation of ternary complexes at very low concentration. The study is important for a comprehensive understanding of the metal-microalgae interaction and its biogeochemical cycle in surface waters.
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•The two-step adsorption model well fits the adsorption curve of Pb and FA by algae.•Pb was adsorbed by algae in the form of free ions at the first layer.•Algae adsorbed Pb-FA complex through adsorbed Pb2+ at the second layer.•FA plays a completion role at the first layer and a ligand role at the second layer.
The inherent challenges in using metal‐organic frameworks (MOFs) for photocatalytic CO2 reduction are the combination of wide‐range light harvesting, efficient charge separation and transfer as well ...as highly exposed catalytic active sites for CO2 activation and reduction. We present here a promising solution to satisfy these requirements together by modulating the crystal facet and surface atomic structure of a porphyrin‐based bismuth‐MOF (Bi‐PMOF). The series of structural and photo‐electronic characterizations together with photocatalytic CO2 reduction experiment collectively establish that the enriched Bi active sites on the (010) surface prefer to promote efficient charge separation and transfer as well as the activation and reduction of CO2. Specifically, the Bi‐PMOFs‐120‐F with enriched surface Bi active sites exhibits optimal photocatalytic CO2 reduction performance to CO (28.61 μmol h−1g−1) and CH4 (8.81 μmol h−1g−1). This work provides new insights to synthesize highly efficient main group p‐block metal Bi‐MOF photocatalysts for CO2 reduction through a facet‐regulation strategy and sheds light on the surface structure‐activity relationships of the MOFs.
A porphyrin‐based Bi‐MOF with enriched surface Bi active sites were obtained by modulating the crystal facet ingeniously. The knitting of Bi active sites onto the porphyrin ligands with the exposure of rich Bi sites can not only ameliorate the light absorption, but also stabilize the catalytic active sites and promote efficient ligand‐to‐metal charge transfer, for significantly ameliorating the performance of photo‐reduction of CO2 to CO and CH4.
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