Dynamic analysis of a simplified flexible manipulator with interval joint clearances and random material properties

Abstract(#br)Flexible manipulator is an emerging technique in aerospace engineering, especially in the assembly, testing and maintenance of space stations. Dynamic analysis of a flexible manipulator with multiple clearance joints and hybrid uncertainties is a great challenge as compared to traditional flexible manipulator. To solve the problem, a dynamics model for a simplified flexible manipulator with interval clearance joints and random material properties was established. In this model, the Lankarani–Nikravesh contact force model was used to construct the clearance joint, while a combined feedforward–feedback control strategy based on a PID controller was applied to control the flexible manipulator. In addition, the clearance sizes and the Young’s moduli of the flexible parts were..

Demonstration of laser-produced neutron diagnostic by radiative capture gamma-rays

We report a new scenario of time-of-flight (TOF) technique in which fast neutrons and delayed gamma-ray signals were both recorded in a millisecond time window in harsh environments induced by high-intensity lasers. The delayed gamma signals, arriving far later than the original fast neutron and often being ignored previously, were identified to be the results of radiative captures of thermalized neutrons. The linear correlation between gamma photon number and the fast neutron yield shows that these delayed gamma events can be employed for neutron diagnosis. This method can reduce the detecting efficiency dropping problem caused by prompt high-flux gamma radiation, and provides a new way for neutron diagnosing in high-intensity laser-target interaction experiments

The Capability Approach to Adolescent Poverty in China: Application of a Latent Class Model

After 2020, poverty alleviation in China will shift from eliminating absolute poverty to alleviating unbalanced and insufficient relative poverty. Based on Amartya Sen’s capability approach, this article aimed to realize the freedom of “capability” of children and ensure the well-being and development of Chinese adolescents, who are often ignored in child poverty research. The study sought to estimate the 10–15-year-olds in a multidimensional capabilities poverty group. Our analysis was based on the adolescent capability methodology framework, using data from the 2018 China Family Panel Studies (CFPS) to investigate the types and influencing factors of adolescent capability poverty in China. The result of latent class analysis showed that there are four types of capability poverty among the Chinese adolescents, namely, Extreme Capability Poverty Class, Goal Capability Poverty Class, Opportunity Capability Poverty Class, and Capability Non-Poverty Class. Multinomial logistic regression showed that the personal factors of gender, ethnic minority, hukou, and pocket money; the family factors of parents’ marital status, parents’ education level, and region of residence; and the family economic factor of per capita family income had a significant impact on the types of China’s adolescent capability poverty. The article provides empirical and quantitative evidence for the adolescent (ages 10–15) class of capability poverty. The findings provide a reference for policy makers to target poverty-alleviation efforts according to different types of poverty and to interrupt the intergenerational transmission of poverty

Machine learning-based signature of necrosis-associated lncRNAs for prognostic and immunotherapy response prediction in cutaneous melanoma and tumor immune landscape characterization

BackgroundCutaneous melanoma (CM) is one of the malignant tumors with a relative high lethality. Necroptosis is a novel programmed cell death that participates in anti-tumor immunity and tumor prognosis. Necroptosis has been found to play an important role in tumors like CM. However, the necroptosis-associated lncRNAs’ potential prognostic value in CM has not been identified.MethodsThe RNA sequencing data collected from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression Project (GTEx) was utilized to identify differentially expressed genes in CM. By using the univariate Cox regression analysis and machine learning LASSO algorithm, a prognostic risk model had been built depending on 5 necroptosis-associated lncRNAs and was verified by internal validation. The performance of this prognostic model was assessed by the receiver operating characteristic curves. A nomogram was constructed and verified by calibration. Furthermore, we also performed sub-group K-M analysis to explore the 5 lncRNAs’ expression in different clinical stages. Function enrichment had been analyzed by GSEA and ssGSEA. In addition, qRT-PCR was performed to verify the five lncRNAs’ expression level in CM cell line (A2058 and A375) and normal keratinocyte cell line (HaCaT).ResultsWe constructed a prognostic model based on five necroptosis-associated lncRNAs (AC245041.1, LINC00665, AC018553.1, LINC01871, and AC107464.3) and divided patients into high-risk group and low-risk group depending on risk scores. A predictive nomogram had been built to be a prognostic indicator to clinical factors. Functional enrichment analysis showed that immune functions had more relationship and immune checkpoints were more activated in low-risk group than that in high-risk group. Thus, the low-risk group would have a more sensitive response to immunotherapy.ConclusionThis risk score signature could be used to divide CM patients into low- and high-risk groups, and facilitate treatment strategy decision making that immunotherapy is more suitable for those in low-risk group, providing a new sight for CM prognostic evaluation

Compressed ultrafast photography by multi-encoding imaging

Imaging ultrafast dynamic scenes has been long pursued by scientists. As a two-dimensional dynamic imaging technique, compressed ultrafast photography (CUP) provides the fastest receive-only camera to capture transient events. This technique is based on three-dimensional image reconstruction by combining streak imaging with compressed sensing (CS). However, the image quality and the frame rate of CUP are limited by the CS-based image reconstruction algorithms and the inherent temporal and spatial resolutions of the streak camera. Here, we report a new method to improve the temporal and spatial resolutions of CUP. Our numerical simulation and experimental verification show that by using a multi-encoding imaging method, both the image quality and the frame rate of CUP can be significantly improved beyond the intrinsic technical parameters. Importantly, the temporal resolution by our scheme can break the limitation of the streak camera. Therefore, this new technology has potential benefits in many applications that require the ultrafast dynamic scene image with high temporal and spatial resolutions

Injectable ferrimagnetic silk fibroin hydrogel for magnetic hyperthermia ablation of deep tumor

Due to the well-recognized biocompatibility, silk fibroin hydrogels have been developed for biomedical appli-cations including bone regeneration, drug delivery and cancer therapy. For the treatment of cancer, silk-based photothermal agents exhibit the high photothermal conversion efficiency, but the limited light penetration depth of photothermal therapy restricts the treatment of some tumors in deep positions, such as liver tumor and glioma. To provide an alternative strategy, here we developed an injectable magnetic hydrogel based on silk fibroin and iron oxide nanocubes (IONCs). The as-prepared ferrimagnetic silk fibroin hydrogel could be easily injected through a syringe into tumor, especially rabbit hepatocellular carcinoma in deeper positions using ultrasound-guided interventional treatment. Compared with photothermal agents, the embedded IONCs endowed the ferrimagnetic silk fibroin hydrogel with remote hyperthermia performance under an alternating magnetic field, resulting in the effective magnetic hyperthermia of deep tumors including subcutaneously implanted tumor model in Balb/c mouse after the coverage of a fresh pork tissue and orthotopic transplantation liver tumor in rabbit. Furthermore, due to the confinement of IONCs in silk fibroin hydrogel, the undesired thermal damage toward normal tissue could be avoided compared with directly administrating monodispersed magnetic nanoparticles