Search

Elastic metamaterials (EMMs) can attenuate surface Rayleigh waves effectively, However, it still hard to put EMMs in practical engineering applications. To overcome this limitation, specific combinations of effective parameters for Rayleigh waves isolation have been determined based on propagation behavior of Rayleigh waves in the semi-infinite EMM. Then, unit cell with negative hybrid bands has been designed to satisfy the requirements of effective parameters. Finally, a new type of metamaterial surface (MMS) was proposed to isolate Rayleigh waves, numerical results show that the peak value of acceleration on surface with proposed MMS can be decreased by 97.2% under seismic wave. [ABSTRACT FROM AUTHOR]

A double‐layered substrate three magnetic side wall cavity (TMSWC) and three‐layered configuration with stacked double TMSWCs are proposed. These structures can realize miniaturization by equivalent magnetic walls inside closed cavities and avoid radiation at the same time. Based on the above three‐layered form, a compact four‐pole single passband filter is designed and fabricated. The measured results agree well with the simulated ones. [ABSTRACT FROM AUTHOR]

The most prominent dynamic characteristic of metamaterials is that they possess the frequency pass bands and band gaps. In the bandgap, the elastic waves will attenuate significantly, and this property is potentially used to control low-frequency vibrations in civil engineering. To open the low-frequency bandgap of the Timoshenko beam, inerter-based dynamic vibration absorbers (IDVAs) are arranged periodically in the beam. An analytical methodology based on transfer matrix method was developed to predict the flexural wave dispersion characteristics, and was validated by test and numerical experiments. The band gaps can be simultaneously tuned by the parameters of the IDVAs, including spring stiffness, inertance and attached mass. Moreover, the band gaps generated by single IDVAs are independent of each other, and a super-wide bandgap can be achieved by splicing the band gaps for metamaterial beams with graded IDVAs. Explicit formulas with respect to the parameters of IDVAs have been developed to determine the condition of bandgap merging, which can broaden the bandwidth effectively. Finally, a computer-based program was presented to determine the reasonable design parameters. [ABSTRACT FROM AUTHOR]

As footbridges are lightweight and slender structures, they are highly sensitive to human-induced excitation, and control measures are required to suppress undesirable structural vibrations. As wave propagation is improbable within a band gap, this study introduces a band gap in a footbridge and develops a new technique as an alternative to suppress the human-induced vibration response. Inerter-based dynamic vibration absorbers (IDVAs) are arranged periodically in the footbridge, which can convert the conventional box girder into a specially designed periodic metamaterial beam with a local resonance band gap. Following the spectral element method, the band gap structure of the metamaterial beam with IDVAs is proposed and validated by test results and numerical experiments. The band gap structure can be simultaneously tuned by the parameters of the IDVAs, including spring stiffness, inertance, and attached mass. A computer-based program was presented to determine the reasonable design parameters of IDVAs. Finally, a new vibration attenuation method for footbridges is proposed based on the theory of metamaterials and validated by numerical experiments. The results show that the proposed method exhibits good performance in vibration attenuation. [ABSTRACT FROM AUTHOR]

Strut‐and‐tie models (STMs) have been widely used to design disturbed regions in structural concrete members. Recently, topology optimization methods, based on the principle of minimum strain energy directly and indirectly, have been adopted to generate STMs in reinforced concrete structures. Unfortunately, current topology optimization methods do not work in many typical disturbed regions. The optimization history of the rectangular anchorage zones shows that the principle of minimum strain energy is a necessary condition for STM, not a sufficient condition. Because, it fails to capture the load transfer path properly in structural concrete tensile regions. To address this issue, a modified optimality criterion is proposed to illustrate the load path in tensile regions. And the desired STM is the one with the maximum overall stiffness and minimum strain energy of the tie. The STM of the rectangular anchorage zones and dapped beams have been developed successfully, and verified by the current ACI 318‐08 code recommendations and experimental evidence. [ABSTRACT FROM AUTHOR]

In the past decades, significant progress has been made in prediction of the structural behavior of the posttensioned anchorage zones, an aspect which has not yet been sufficiently clear up, however, is the serviceability behavior of posttensioned anchorage zones, especially with regard to the crack formation. To address this problem, a numerical method based on linear elastic fracture mechanics is proposed to investigate the crack propagation in posttensioned anchorage zones, and predict the structural behavior in the serviceability state. Following Irwin's approach, an effective crack length is proposed for I‐II mixed‐mode crack growth. The numerical analyses of the tested anchorage zone specimens show that the proposed procedure is able to accurately describe the crack propagation behavior, including crack length, crack width, and crack trace. Parameter analysis is performed to study the effects of the layout of the reinforcement on crack width in the service state. The results show that the proper bursting rebar diameters and rebar spacing can lead to the significant decrease of the crack width, while the longitudinal rebar makes little contribution to cracking control. [ABSTRACT FROM AUTHOR]

The strut‐and‐tie model (STM) has been adopted as a preferred methodology for the design of disturbed regions; however, an aspect which has not yet been sufficiently cleared up is the serviceability behavior of structural concrete, especially with regard to the cracking prediction. To address this issue, this paper is devoted to developing an advanced elastic‐to‐plastic strut‐and‐tie model (EPSTM) to capture the full elastic and inelastic response of the anchorage zones. The principle of stationary complementary energy is introduced into the STM to satisfy the compatibility and generate the adaptive EPSTM at each load step. The proposed EPSTM provides a consistent analysis of the behavior of anchorage zones, including the average strain of struts and ties, load‐deformation response and the maximum crack width, throughout the loading process, and has been verified to be sufficiently accurate by comparing with testing results. [ABSTRACT FROM AUTHOR]

The dynamic response of a cracked beam subjected to moving loads has been studied extensively in the past decades. However, very little is known about the dynamic impact factors and crack propagation when vehicles move along the cracked beam. It can be reasonably postulated that a crack extension may occur when the vehicle loads cross the cracked bridge at a high speed. As a result, the dynamic response will be enlarged significantly due to the flexural rigidity reduction induced by cracks, which may result in a dangerous effect on structures. To address this problem, a three-dimensional vehicle-bridge model was developed to investigate the dynamic response of cracked bridges with crack breathing. Crack breathing is simulated at the crack surface using contact elements. The modified crack closure method is adopted to calculate the stress intensity factors. The results showed that the impact factors for the damaged bridge under a moving load could be notably larger than those for the intact bridge, and could exceed the value specified in the AASHTO bridge design code. Meanwhile, crack propagation may occur when the vehicles move along the cracked bridge at a high speed. So, it is very necessary to limit the velocity and transverse position of the vehicles to avoid further damage to the cracked bridge. [ABSTRACT FROM AUTHOR]

Background: Sialic acid-bound immunoglobulin lectin 15 (Siglec-15) plays an important role in the development of cancer. However, the association between Siglec-15 expression and clinicopathological characteristics of colorectal cancer (CRC) has not been fully investigated., Methods: In this present study, a number of bioinformatics analyses were performed to provide an overview and detailed characteristics of Siglec-15. Quantitative real-time polymerase chain reaction (qPCR), western blotting and immunohistochemistry analyses were conducted to characterize the expression of Siglec-15 in CRC. Kaplan-Meier survival and Cox regression analyses were performed to identify the prognostic parameters of CRC., Results: The results of bioinformatics analyses revealed the expression characteristics and prognostic roles of Siglec-15 in CRC. The data of qCPR, western blotting, and IHC analyses demonstrated that the expression of Siglec-15 in CRC tissues was significantly higher than that in non-cancerous tissues. Moreover, the expression level of Siglec-15 in CRC was significantly associated with lymph node metastasis (p=0.001), TNM stage (p=0.001), and overall survival (p=0.026). COX multi-factor analysis indicated that Siglec-15 expression (p=0.023) and tumor differentiation (p=0.003) were independent prognostic factors for CRC., Conclusions: Collectively, the data suggested that Siglec-15 expression may serve as a novel prognostic factor and Siglec-15 might be identified as an ideal candidate for immunotherapy in CRC treatment., (©The Author(s) 2024. Open Access. This article is licensed under a Creative Commons CC-BY International License.)

Objectives: To examine the temporal patterns of patient characteristics, treatments used and outcomes associated with COVID-19 in patients who were hospitalised for the disease between January and 15 November 2020., Design: Observational cohort study., Setting: COVID-19 subset of the Optum deidentified electronic health records, including more than 1.8 million patients from across the USA., Participants: There were 51 510 hospitalised patients who met the COVID-19 definition, with 37 617 in the laboratory positive cohort and 13 893 in the clinical cohort., Primary and Secondary Outcome Measures: Incident acute clinical outcomes, including in-hospital all-cause mortality., Results: Respectively, 48% and 49% of the laboratory positive and clinical cohorts were women. The 50- 65 age group was the median age group for both cohorts. The use of antivirals and dexamethasone increased over time, fivefold and twofold, respectively, while the use of hydroxychloroquine declined by 98%. Among adult patients in the laboratory positive cohort, absolute age/sex standardised incidence proportion for in-hospital death changed by -0.036 per month (95% CI -0.042 to -0.031) from March to June 2020, but remained fairly flat from June to November, 2020 (0.001 (95% CI -0.001 to 0.003), 17.5% (660 deaths /3986 persons) in March and 10.2% (580/5137) in October); in the clinical cohort, the corresponding changes were -0.024 (95% CI -0.032 to -0.015) and 0.011 (95% CI 0.007 0.014), respectively (14.8% (175/1252) in March, 15.3% (189/1203) in October). Declines in the cumulative incidence of most acute clinical outcomes were observed in the laboratory positive cohort, but not for the clinical cohort., Conclusion: The incidence of adverse clinical outcomes remains high among COVID-19 patients with clinical diagnosis only. Patients with COVID-19 entering the hospital are at elevated risk of adverse outcomes., Competing Interests: Competing interests: JHP, AAL, CBrooks, JZ, CBennett, BDB, MB, CAB, PC, AC, CWC, KG, FH, JM, JP and KAR are employees and stockholders of Amgen. JMS reports consulting for Amgen and owns stock in Amgen. OA, S-CC, GD, KG, HK, KR, LS, LW, PY and LZ are employees and stockholders in Takeda, Pharmaceutical Company Limited. YB, JJ, QX, ZW and JZ are employees and stockholders in Bristol-Myers Squibb. KBC, an employee of Moderna, was formerly an employee of Amgen and owns stock in Amgen. GlaxoSmithKline (GSK), Takeda, AbbVie, Boehringer Ingelheim and UCB Bioscience (UCB) have collaborative agreements with the Center for Pharmacoepidemiology, Department of Epidemiology, University of North Carolina at Chapel Hill which provides salary support to MJ-F and MJ-F is a member of the Scientific Steering Committee (SSC) for a postapproval safety study funded by GSK. All compensation for services provided on the SSC is invoiced by and paid to UNC Chapel Hill., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Online health communities (OHCs) have increasingly gained traction with patients, caregivers, and supporters globally. Chinese OHCs are no exception. However, user-generated content (UGC) and the associated user behaviors in Chinese OHCs are largely underexplored and rarely analyzed systematically, forfeiting valuable opportunities for optimizing treatment design and care delivery with insights gained from OHCs., Objective: This study aimed to reveal both the shared and distinct characteristics of 2 popular OHCs in China by systematically and comprehensively analyzing their UGC and the associated user behaviors., Methods: We concentrated on studying the lung cancer forum (LCF) and breast cancer forum (BCF) on Mijian, and the diabetes consultation forum (DCF) on Sweet Home, because of the importance of the 3 diseases among Chinese patients and their prevalence on Chinese OHCs in general. Our analysis explored the key user activities, small-world effect, and scale-free characteristics of each social network. We examined the UGC of these forums comprehensively and adopted the weighted knowledge network technique to discover salient topics and latent relations among these topics on each forum. Finally, we discussed the public health implications of our analysis findings., Results: Our analysis showed that the number of reads per thread on each forum followed gamma distribution (H L =0, H B =0, and H D =0); the number of replies on each forum followed exponential distribution (adjusted R L 2 =0.946, adjusted R B 2 =0.958, and adjusted R D 2 =0.971); and the number of threads a user is involved with (adjusted R L 2 =0.978, adjusted R B 2 =0.964, and adjusted R D 2 =0.970), the number of followers of a user (adjusted R L 2 =0.989, adjusted R B 2 =0.962, and adjusted R D 2 =0.990), and a user's degrees (adjusted R L 2 =0.997, adjusted R B 2 =0.994, and adjusted R D 2 =0.968) all followed power-law distribution. The study further revealed that users are generally more active during weekdays, as commonly witnessed in all 3 forums. In particular, the LCF and DCF exhibited high temporal similarity (ρ=0.927; P<.001) in terms of the relative thread posting frequencies during each hour of the day. Besides, the study showed that all 3 forums exhibited the small-world effect (mean σ L =517.15, mean σ B =275.23, and mean σ D =525.18) and scale-free characteristics, while the global clustering coefficients were lower than those of counterpart international OHCs. The study also discovered several hot topics commonly shared among the 3 disease forums, such as disease treatment, disease examination, and diagnosis. In particular, the study found that after the outbreak of COVID-19, users on the LCF and BCF were much more likely to bring up COVID-19-related issues while discussing their medical issues., Conclusions: UGC and related online user behaviors in Chinese OHCs can be leveraged as important sources of information to gain insights regarding individual and population health conditions. Effective and timely mining and utilization of such content can continuously provide valuable firsthand clues for enhancing the situational awareness of health providers and policymakers., (©Yuqi Lei, Songhua Xu, Linyun Zhou. Originally published in the Journal of Medical Internet Research (https://www.jmir.org), 15.12.2021.)

Objective: To examine age, gender, and temporal differences in baseline characteristics and clinical outcomes of adult patients hospitalised with COVID-19., Design: A cohort study using deidentified electronic medical records from a Global Research Network., Setting/participants: 67 456 adult patients hospitalised with COVID-19 from the USA; 7306 from Europe, Latin America and Asia-Pacific between February 2020 and January 2021., Results: In the US cohort, compared with patients 18-34 years old, patients ≥65 had a greater risk of intensive care unit (ICU) admission (adjusted HR (aHR) 1.73, 95% CI 1.58 to 1.90), acute respiratory distress syndrome(ARDS)/respiratory failure (aHR 1.86, 95% CI 1.76 to 1.96), invasive mechanical ventilation (IMV, aHR 1.93, 95% CI, 1.73 to 2.15), and all-cause mortality (aHR 5.6, 95% CI 4.36 to 7.18). Men appeared to be at a greater risk for ICU admission (aHR 1.34, 95% CI 1.29 to 1.39), ARDS/respiratory failure (aHR 1.24, 95% CI1.21 to 1.27), IMV (aHR 1.38, 95% CI 1.32 to 1.45), and all-cause mortality (aHR 1.16, 95% CI 1.08 to 1.24) compared with women. Moreover, we observed a greater risk of adverse outcomes during the early pandemic (ie, February-April 2020) compared with later periods. In the ex-US cohort, the age and gender trends were similar; for the temporal trend, the highest proportion of patients with all-cause mortality were also in February-April 2020; however, the highest percentages of patients with IMV and ARDS/respiratory failure were in August-October 2020 followed by February-April 2020., Conclusions: This study provided valuable information on the temporal trends of characteristics and outcomes of hospitalised adult COVID-19 patients in both USA and ex-USA. It also described the population at a potentially greater risk for worse clinical outcomes by identifying the age and gender differences. Together, the information could inform the prevention and treatment strategies of COVID-19. Furthermore, it can be used to raise public awareness of COVID-19's impact on vulnerable populations., Competing Interests: Competing interests: YB, XC, JJ, QX, MS, ZW and JZ are employees of Bristol Myers Squibb and hold stock or stock options at Bristol Myers Squibb. BDB, CB, CAB, AC, CWC, AAL, JM, JZ are employees and stockholders of Amgen. OA, GD, VG, KG, HAK, SM, KR, LS, PY and LZ are employees and stockholders in Takeda, Pharmaceutical Company Limited. GlaxoSmithKline (GSK), Takeda, AbbVie, Boehringer Ingelheim and UCB Bioscience (UCB) have collaborative agreements with the Center for Pharmacoepidemiology, Department of Epidemiology and University of North Carolina at Chapel Hill which provides salary support to MJ-F as Director. MJ-F is a member of the Scientific Steering Committee (SSC) for a postapproval safety study funded by GSK. All compensation for services provided on the SSC is invoiced by and paid to UNC Chapel Hill., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: The objective of this study was to establish a culture system and elucidate the unique characteristics of a bovine mammary epithelial cell line in vitro., Methodology: Mammary tissue from a three year old lactating dairy cow (ca. 100 d relative to parturition) was used as a source of the epithelial cell line, which was cultured in collagen-coated tissue culture dishes. Fibroblasts and epithelial cells successively grew and extended from the culturing mammary tissue at the third day. Pure epithelial cells were obtained by passages culture., Principal Findings: The strong positive immunostaining to cytokeratin 18 suggested that the resulting cell line exhibited the specific character of epithelial cells. Epithelial cells cultured in the presence of 10% FBS, supraphysiologic concentrations of insulin, and hydrocortisone maintained a normal diploid chromosome modal number of 2n=60. Furthermore, they were capable of synthesizing beta-casein (CSN2), acetyl-CoA carboxylase-alpha (ACACA) and butyrophilin (BTN1A1). An important finding was that frozen preservation in a mixture of 90% FBS and 10% DMSO did not influence the growth characteristics, chromosome number, or protein secretion of the isolated epithelial cell line., Conclusions: The obtained mammary epithelial cell line had normal morphology, growth characteristics, cytogenetic and secretory characteristics, thus, it might represent an useful tool for studying the function of Chinese Holstein dairy cows mammary epithelial cell (CMECs).