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1.
Br J Neurosurg ; : 1-7, 2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34612789

RESUMO

PURPOSE: The occiput-axis crossing translaminar screw (C2LAM) fixation technique can help avoid vertebral injury, while the inclusion of offset connectors can facilitate implantation. This three-dimensional finite element (FE) study compared the stability of C2LAM using offset connectors (C2LAM + OF) with other methods. MATERIALS AND METHODS: Occipital and cervical spine computed tomography images of a healthy 30-year-old man were selected to build the FE model. Four internal fixation instruments including occiput plate-C2 pedicle (C2P) and pars (C2Pars) screws, as well as C2LAM and C2LAM + OF were applied consecutively to the model respectively to establish four new models, which were subjected to all states of motion and physiological loads to simulate normal movement, including the four kinds of basic activities of human such as flexion, extension, lateral bending, and axial rotation. Physiological measures and comparison included the range of motion (ROM) and stress distribution in the model. RESULTS: ROM between the fixation techniques was comparable, and the stability of the C2LAM + OF fixation technique was similar to that of C2P. Screw entry points, offset connectors and rods were the main stress distribution regions in the C2LAM + OF system. The mean von Mises stress of the inner wall was significantly smaller than that of the outer wall in flexion, extension, and rotation (p < 0.05); however, lateral bending was comparable, indicating a relatively small risk of damage to the inner wall. CONCLUSIONS: The results of this study indicate that the C2LAM + OF fusion technique can provide sufficient stability and can be used as an alternative to C2P under special circumstances.

2.
Accid Anal Prev ; 163: 106429, 2021 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-34638010

RESUMO

Freeway jam waves create many problems, including capacity reduction, travel delays, and safety risks. The development of cooperative vehicle infrastructure system (CVIS) has prompted numerous new strategies, which can resolve jam waves by implementing microscopic car-following control actions to individual vehicles. However, most of those strategies aimed at eliminating freeway jam waves without considering the safety risks induced by the car-following control. This paper proposes an optimal control-based vehicle speed guidance strategy to improve both traffic efficiency and safety against jam waves. The optimal controller is developed based on a discrete first-order traffic flow model formulated in Lagrangian coordinates. The optimization of vehicles' driving speed is formulated as a linear programming problem, where the constraints concerning threshold safety measures are imposed. The proposed vehicle speed guidance strategy is tested using a modified Intelligent Driving Model (IDM+), which represents real traffic dynamics in CVIS environment. The proposed speed guidance strategy is compared with a state-of-the-art jam-absorption driving strategy, which also aimed to eliminate freeway jam waves. Simulation results show that the proposed strategy outperforms that strategy in terms of both total time spent saving and surrogate safety measures' reduction. The time exposed time-to-collision (TET) is reduced by 31%, and the time integrated time-to-collision (TIT) is reduced by 9.5% on average. Furthermore, the computation time of the linear optimization is only a few seconds, which is fast enough for the online application of the proposed strategy.

3.
Technol Cancer Res Treat ; 20: 15330338211036325, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34490802

RESUMO

PURPOSE: In radiotherapy, geometric indices are often used to evaluate the accuracy of contouring. However, the ability of geometric indices to identify the error of contouring results is limited primarily because they do not consider the clinical background. The purpose of this study is to investigate the relationship between geometric and clinical dosimetric indices. METHODS: Four different types of targets were selected (C-shaped target, oropharyngeal cancer, metastatic spine cancer, and prostate cancer), and the translation, scaling, rotation, and sine function transformation were performed with the software Python to introduce systematic and random errors. The transformed contours were regarded as reference contours. Dosimetric indices were obtained from the original dose distribution of the radiotherapy plan. The correlations between geometric and dosimetric indices were quantified by linear regression. RESULTS: The correlations between the geometric and dosimetric indices were inconsistent. For systematic errors, and with the exception of the sine function transformation (R2: 0.023-0.04, P > 0.05), the geometric transformations of the C-shaped target were correlated with the D98% and Dmean (R2: 0.689-0.988), 80% of which were P < 0.001. For the random errors, the correlations obtained by the all targets were R2 > 0.384, P < 0.05. The Wilcoxon signed-rank test was used to compare the spatial direction resolution capability of geometric indices in different directions of the C-shaped target (with systematic errors), and the results showed only the volumetric geometric indices with P < 0.05. CONCLUSIONS: Clinically, an assessment of the contour accuracy of the region-of-interest is not feasible based on geometric indices alone. Dosimetric indices should be added to the evaluations of the accuracy of the delineation results, which can be helpful for explaining the clinical dose response relationship of delineation more comprehensively and accurately.

4.
Artigo em Inglês | MEDLINE | ID: mdl-34516378

RESUMO

Stroke is a world-leading disease for causing disability. Brain-computer interaction (BCI) training has been proved to be a promising method in facilitating motor recovery. However, due to differences in each patient's neural-clinical profile, the potential of recovery for different patients can vary significantly by conducting BCI training, which remains a major problem in clinical rehabilitation practice. To address this issue, the objective of this study is to prognosticate the outcome of BCI training using motor state electroencephalographic (EEG) collected during the first session of BCI tasks, with the aim of prescribing BCI training accordingly. A Convolution Neural Network (CNN) based prognosis model was developed to predict the outcome of 11 stroke patients' recovery following a 2-week rehabilitation training with BCI. In our study, functional connectivity and power spectrum have been evaluated and applied as the inputs of CNN to regress patients' recovery rate. A saliency map was used to identify the correlation between EEG channels with the recovery outcome. The performance of our model was assessed using the leave-one-out cross-validation. Overall, the proposed model predicted patients' recovery with R2 0.98 and MSE 0.89. According to the saliency map, the highest functional connectivity occurred in Fp2/Fpz-AF8, Fp2/F4/F8-P3, P1/PO7-PO5 and AF3-AF4. Our results demonstrated that deep learning method has the potential to predict the recovery rate of BCI training, which contributes to guiding individualized prescription in the early stage of clinical rehabilitation.

5.
Anat Rec (Hoboken) ; 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34347376

RESUMO

Lung cancer is characterized by a high incidence rate and low survival rate. It is important to achieve early diagnosis of the disease. We applied ultra-high performance liquid chromatography tandem mass spectrometry to screen plasma lipid spectrum in non-small cell lung cancer (NSCLC) patients, healthy controls (HC), and community-acquired pneumonia (CAP) patients. Modeling employing orthogonal partial least squares-discriminant analysis combined with t-test was used to screen the differential lipids. Logistic regression analysis was used to establish the diagnostic model, while the accuracy was verified by 10-fold cross-validation. The results showed that the abnormal metabolism of lipid in NSCLC mainly comprised fatty acid metabolism, phospholipid metabolism, and glyceride metabolism. Four potential biomarkers, including LPC (14:0/0:0), LPI (14:1/0:0), DG (14:0/18:2/0:0), and LPC (16:1/0:0), were fitted by the receiver operating characteristic curve model with the area under curve (AUC) value of 0.856, and the specificity and sensitivity were 87.0 and 78.0%, respectively. The results of cross validation showed that the AUC value of the model was 0.812, the sensitivity was 72.9%, and the specificity was 82.6%. The positive rate of four potential lipid biomarkers in this study (>60.0%) was higher than that of existing tumor biomarkers in the clinical application. We investigated the plasma lipid profile of NSCLC patients and identified lipid biomarkers with potential diagnostic values. From the lipidomics perspective, our study may lay a foundation for the biomarker-based early diagnosis of lung cancer.

6.
Nanomicro Lett ; 13(1): 179, 2021 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-34406514

RESUMO

As one of the promising anode materials, iron selenide has received much attention for potassium-ion batteries (KIBs). Nevertheless, volume expansion and sluggish kinetics of iron selenide result in the poor reversibility and stability during potassiation-depotassiation process. In this work, we develop iron selenide composite matching ether-based electrolyte for KIBs, which presents a reversible specific capacity of 356 mAh g-1 at 200 mA g-1 after 75 cycles. According to the measurement of mechanical properties, it is found that iron selenide composite also exhibits robust and elastic solid electrolyte interphase layer in ether-based electrolyte, contributing to the improvement in reversibility and stability for KIBs. To further investigate the electrochemical enhancement mechanism of ether-based electrolyte in KIBs, we also utilize in situ visualization technique to monitor the potassiation-depotassiation process. For comparison, iron selenide composite matching carbonate-based electrolyte presents vast morphology change during potassiation-depotassiation process. When changing to ether-based electrolyte, a few minor morphology changes can be observed. This phenomenon indicates an occurrence of homogeneous electrochemical reaction in ether-based electrolyte, which results in a stable performance for potassium-ion (K-ion) storage. We believe that our work will provide a new perspective to visually monitor the potassium-ion storage process and guide the improvement in electrode material performance.

7.
Nat Nanotechnol ; 16(10): 1150-1160, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34354264

RESUMO

Although nanomaterials have shown promising biomedical application potential, incomplete understanding of their molecular interactions with biological systems prevents their inclusion into mainstream clinical applications. Here we show that black phosphorus (BP) nanomaterials directly affect the cell cycle's centrosome machinery. BP destabilizes mitotic centrosomes by attenuating the cohesion of pericentriolar material and consequently leads to centrosome fragmentation within mitosis. As a result, BP-treated cells exhibit multipolar spindles and mitotic delay, and ultimately undergo apoptosis. Mechanistically, BP compromises centrosome integrity by deactivating the centrosome kinase polo-like kinase 1 (PLK1). BP directly binds to PLK1, inducing its aggregation, decreasing its cytosolic mobility and eventually restricting its recruitment to centrosomes for activation. With this mechanism, BP nanomaterials show great anticancer potential in tumour xenografted mice. Together, our study reveals a molecular mechanism for the tumoricidal properties of BP and proposes a direction for biomedical application of nanomaterials by exploring their intrinsic bioactivities.

8.
Artigo em Inglês | MEDLINE | ID: mdl-34433546

RESUMO

INTRODUCTION: We aimed to evaluate the joint associations of metabolically healthy abdominal obesity (MHAO) with non-alcoholic fatty liver disease (NAFLD) on risks of diabetes and prediabetes. RESEARCH DESIGN AND METHODS: Baseline information of 1318 adults with abdominal obesity (waist circumference ≥90 cm for men and 80 cm for women) from an ongoing cohort study in Xiamen, China were analyzed. Metabolic health was identified as none of the criteria of metabolism syndrome, except for obesity, was met. RESULTS: MHAO and metabolically unhealthy abdominal obesity (MUAO) were identified on 173 (13.1%) and 1145 (86.9%) subjects. NAFLD was further diagnosed on 60 (34.7%) in MHAO and 721 (63.0%) in MUAO groups (p<0.001). Both MUAO (vs MHAO) and NAFLD (vs non-NAFLD) were independently associated with increased risks of diabetes as well as prediabetes plus diabetes, with the adjusted ORs (95% CIs) of 9.40 (3.38 to 26.14) and 2.02 (1.47 to 2.77), respectively. Compared with MHAO and non-NAFLD, MHAO and NAFLD showed significantly increased risks of prediabetes plus diabetes with the adjusted ORs (95% CIs) of 2.87 (1.32 to 6.27, p=0.008). And there were significantly positive trends between increasing categories jointly by MHAO and NAFLD (from MHAO and non-NAFLD, MHAO and NAFLD, MUAO and non-NAFLD to MUAO and NAFLD) with risks of diabetes and prediabetes plus diabetes (both trend tests: p<0.001). CONCLUSIONS: About 35% of subjects with MHAO accompanied by NAFLD showed excessive risk of prediabetes plus diabetes compared with MHAO and non-NAFLD. Thus, NAFLD should be screened and intervened even for those subjects with metabolically healthy obesity (MHO) and should be considered as one additional criterion when defining and diagnosing MHO.


Assuntos
Diabetes Mellitus , Hepatopatia Gordurosa não Alcoólica , Obesidade Abdominal , Obesidade Metabolicamente Benigna , Estado Pré-Diabético , Adulto , China/epidemiologia , Estudos de Coortes , Diabetes Mellitus/epidemiologia , Feminino , Humanos , Masculino , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Obesidade Abdominal/complicações , Obesidade Abdominal/epidemiologia , Estado Pré-Diabético/diagnóstico , Estado Pré-Diabético/epidemiologia , Fatores de Risco
9.
Phys Med ; 89: 243-249, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34428608

RESUMO

PURPOSE: To assess the effectiveness of SGRT in clinical applications through statistical process control (SPC). METHODS: Taking the patients' positioning through optical surface imaging (OSI) as a process, the average level of process execution was defined as the process mean. Setup errors detected by cone-beam computed tomography (CBCT) and OSI were extracted for head-and-neck cancer (HNC) and breast cancer patients. These data were used to construct individual and exponentially weighted moving average (EWMA) control charts to analyze outlier fractions and small process shifts from the process mean. Using the control charts and process capability indices derived from this process, the patient positioning-related OSI performance and setup error were analyzed for each patient. RESULTS: Outlier fractions and small shifts from the process mean that are indicative of setup errors were found to be widely prevalent, with the outliers randomly distributed between fractions. A systematic error of up to 1.6 mm between the OSI and CBCT results was observed in all directions, indicating a significantly degraded OSI performance. Adjusting this systematic error for each patient using setup errors of the first five fractions could effectively mitigate these effects. Process capability analysis following adjustment for systematic error indicated that OSI performance was acceptable (process capability index Cpk = 1.0) for HNC patients but unacceptable (Cpk < 0.75) for breast cancer patients. CONCLUSION: SPC is a powerful tool for detecting the outlier fractions and process changes. Our application of SPC to patient-specific evaluations validated the suitability of OSI in clinical applications involving patient positioning.


Assuntos
Neoplasias da Mama , Neoplasias de Cabeça e Pescoço , Radioterapia Guiada por Imagem , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/radioterapia , Tomografia Computadorizada de Feixe Cônico , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Posicionamento do Paciente , Planejamento da Radioterapia Assistida por Computador , Erros de Configuração em Radioterapia
10.
Ultrason Sonochem ; 77: 105668, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34298307

RESUMO

To extend the shelf life and retain bioactive proteins in milk, this study utilized microfiltration (MF) combined with ultrasonication to treat skim milk and investigated its efficiency in removing bacteria and retaining bioactive proteins compared with HTST pasteurization and microfiltration alone. Results showed that microfiltration combined with ultrasonication at 1296 J/mL could completely remove the bacteria in skim milk. Ultrasonication further extended the shelf life (4 °C) of microfiltered skim milk, which could reach at least 40 days when MF was combined with ˃1296 J/mL ultrasonication. In addition, ELISA showed that HTST pasteurization significantly decreased the levels of IgG by ~30%, IgA by ~ 50%, IgM by ~60%, and lactoferrin by ~40%, whereas the activity of the enzymes lactoperoxidase and xanthine oxidase were also decreased by ~ 20%. Compared with HTST, MF alone or combined with ultrasonication retained these bioactive proteins to a larger degree. On the other hand, proteomics indicated both damage to casein micelle and fat globule structures in milk when ultrasonication at >1296 J/mL was applied, as shown by increases in caseins and milk fat globular proteins. Simultaneously, this ultrasound intensity also decreased levels of bioactive proteins, such as complement factors. Taken together, this study provided new insights that may help to implement this novel combination of non-thermal technologies for the dairy industry aimed at improving milk quality and functionality.


Assuntos
Filtração , Armazenamento de Alimentos , Leite/química , Proteínas/química , Sonicação , Animais , Temperatura
13.
Am Heart J ; 238: 45-58, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33957103

RESUMO

BACKGROUND: Diabetes has become a major public health challenge worldwide, especially in low- and middle-income countries (LMICs). Uncontrolled hyperglycemia, hypertension, and dyslipidemia major risk factors for all-cause mortality and cardiovascular disease (CVD) are common in patients with diabetes in China. We propose to compare the effectiveness of team-based care plus a clinical decision support system (CDSS) with team-based care alone on glycemic, blood pressure (BP), and lipid control, and clinical CVD reduction among patients with type-2 diabetes and at high risk for CVD. METHODS: The Diabetes Complication Control in Community Clinics (D4C) study is a cluster-randomized trial conducted among 38 community health centers in Xiamen City, China. Nineteen clinics have been randomly assigned to team-based care plus CDSS and 19 to team-based care alone. Team-based care includes primary care providers, health coaches, and diabetes specialists working collaboratively with patients to achieve shared treatment goals for CVD risk factor reduction. The CDSS integrates guideline-based treatment algorithms for glycemic, BP, and lipid control, along with a patient's medical history and insurance policy, to recommend treatment and follow-up plans. In phase 1, the co-primary outcomes are mean reduction in glycated hemoglobin (HbA1c), systolic BP (SBP), and low-density lipoprotein (LDL)-cholesterol over 18 months, and the proportion of patients with controlled HbA1c, SBP, and LDL-cholesterol at 18 months' between the 2 comparison groups. In phase 2, the primary outcome is the difference in major CVD incidence (non-fatal stroke, non-fatal myocardial infarction, hospitalized heart failure, and CVD mortality) between the 2 comparison groups. Mean reduction in HbA1c, SBP, and LDL-cholesterol levels will be simultaneously modeled for a single overall treatment effect. CONCLUSION: The D4C trial will generate evidence on whether a CDSS will further reduce the CVD burden among patients with diabetes beyond team-based care at community clinics. If proven effective, this implementation strategy could be scaled up within primary care settings in China and other LMICs to reduce CVD incidence and mortality among patients with diabetes.


Assuntos
Doenças Cardiovasculares/prevenção & controle , Sistemas de Apoio a Decisões Clínicas , Diabetes Mellitus Tipo 2/complicações , Fatores de Risco de Doenças Cardíacas , Equipe de Assistência ao Paciente/organização & administração , Comportamento de Redução do Risco , Pressão Sanguínea , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/mortalidade , China , LDL-Colesterol/sangue , Diabetes Mellitus Tipo 2/sangue , Feminino , Hemoglobina A Glicada , Insuficiência Cardíaca/prevenção & controle , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/prevenção & controle , Acidente Vascular Cerebral/prevenção & controle
14.
J Mech Behav Biomed Mater ; 120: 104561, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33965810

RESUMO

Poly-ether-ether-ketone (PEEK) possesses excellent biocompatibility and similar elastic modulus as bones but yet suffers from poor osseointegration. In order to balance PEEK's mechanical and osseointegration properties, a novel surface porous PEEK (SP-PEEK) is successfully fabricated by fused deposition modelling three-dimensional printing (FDM 3DP) and characterized by mechanical and osteogenesis in vitro tests. Moreover, the effects of pore diameter and pore layer number on the mechanical behaviors of SP-PEEK are investigated by theoretical model and numerical simulation. Comparison among experimental, theoretical and simulation results show good agreement. As pore diameter decreases, the equivalent strength and modulus become more sensitive to the decrease of pore layer number. In addition, the SP-PEEK exhibits the mechanical properties within the range of human trabecular bone and cortical bone, and thus can be tailored to mimic human bone by adjusting the pore diameter and pore layer number, which is benefit to mitigate stress shielding. The effects of pore diameter on the cell proliferation and osteogenic differentiation of SP-PEEK are tested by the co-culture of osteoblast precursor cells (MC3T3-E1) and SP-PEEK round discs. Results showcase that porous surface improves the osteogenesis in vitro, and the SP-PEEK group that the pore diameter is 0.6 mm exhibits optimal-performance osteogenesis in vitro.


Assuntos
Cetonas , Osteogênese , Éter , Éteres , Humanos , Polietilenoglicóis , Porosidade , Impressão Tridimensional , Propriedades de Superfície , Suporte de Carga
15.
Biomaterials ; 273: 120788, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33933912

RESUMO

Intrinsic immune behaviors of nanomaterials and immune systems promote research on their adjuvanticity and the design of next generation nanovaccine-based immunotherapies. Herein, we report a promising multifunctional nanoadjuvant by exploring the immune-potentiating effects of black phosphorus nanosheets (BPs) in vitro and in vivo. The facile coating of BPs with phenylalanine-lysine-phenylalanine (FKF) tripeptide-modified antigen epitopes (FKF-OVAp@BP) enables the generation of a minimalized nanovaccine by integrating high loading capacity, efficient drug delivery, comprehensive dendritic cell (DC) activation, and biocompatibility for cancer immunotherapy. Systemic immunization elicits potent antitumor cellular immunity and significantly augments checkpoint blockade (CPB) against melanoma in a mouse model. Furthermore, near-infrared (NIR) photothermal effects of BPs create an immune-favorable microenvironment for improved local immunization. This study offers new insight into the integration of immunoactivity and photothermal effects for enhanced cancer immunotherapy by using a nanoadjuvant and thus potentially advances the design and application of multifunctional adjuvant materials for cancer nanotreatment.


Assuntos
Imunoterapia , Fósforo , Adjuvantes Imunológicos , Animais , Sistemas de Liberação de Medicamentos , Fatores Imunológicos , Camundongos
16.
Accid Anal Prev ; 157: 106191, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34015604

RESUMO

This study employed surrogate safety measures to evaluate the crash risks in different traffic phases and phase transitions according to the three-phase theory. The analysis was conducted from a microscopic perspective based on empirical vehicle trajectory data collected from the Interstate 80 in California, USA, and the Yingtian Expressway in Nanjing, China. Traffic phases were identified based on traffic flow variables and their correlations. Two advanced crash risk indexes from vehicle trajectories were conducted to evaluate the safety performance in each traffic state. The effects of various traffic flow variables (i.e. flow rate, density, average speed) on crash risks were explored based on speed-density plane, speed-flow plane and flow-density plane. Three regression models were developed to quantify the effects of traffic flow variables and traffic states on crash risks. The results show significant disparities of safety performance among different traffic states. Synchronized flow and wide moving jam are found to be the most dangerous phases. High density and low speed are associated with high crash risk. The best crash risk prediction performance is achieved when integrating both traffic phases and traffic parameters.


Assuntos
Condução de Veículo , Acidentes de Trânsito , China , Humanos , Segurança
17.
J Colloid Interface Sci ; 599: 857-862, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33989936

RESUMO

In this work, we developed bismuth oxychloride anchoring on graphene nanosheets (BiOCl/G) composite via a simple one-step hydrothermal process for KIBs' anode, which delivers a high reversible specific capacity of 251 mAh g-1 at 50 mA g-1 after 50 cycles. Meanwhile, our BiOCl/G composite also exhibits a low voltage plateau during potassiation-depotassiation process, and such low voltage plateau in anode is helpful to improve the energy density of the full battery. In addition, we also provide the energy changes for migration of K-ion of our composite according to the density functional theory calculation and the result shows that the introduction of graphene in BiOCl can reduce the adsorption energy variation, which is in favor of K-ion intercalation process. In consideration of low potential plateau of our composite, we also introduce a new evaluation method, relative energy density (ER), which not only includes the specific capacity, but also combines the potential plateau of the anode materials during potassiation-depotassiation process. According to the calculation, our BiOCl/G composite obtain an ultra-high ER of 541 Wh kg-1 at 50 mA g-1 after 50 cycles with a relative energy conversion efficiency of 81%.

18.
Artigo em Inglês | MEDLINE | ID: mdl-33882007

RESUMO

The vehicle platoon will be the most dominant driving mode on future roads. To the best of our knowledge, few reinforcement learning (RL) algorithms have been applied in vehicle platoon control, which has large-scale action and state spaces. Some RL-based methods were applied to solve single-agent problems. If we need to tackle multiagent problems, we will use multiagent RL algorithms since the parameters space grows exponentially with the increasing number of agents involved. Previous multiagent RL algorithms generally may provide redundant information to agents, indicating a large amount of useless or unrelated information, which may cause to be difficult for convergence training and pattern extractions from shared information. Also, random actions usually contribute to crashes, especially at the beginning of training. In this study, a communication proximal policy optimization (CommPPO) algorithm was proposed to tackle the above issues. In specific, the CommPPO model adopts a parameter-sharing structure to allow the dynamic variation of agent numbers, which can well handle various platoon dynamics, including splitting and merging. The communication protocol of the CommPPO consists of two parts. In the state part, the widely used predecessor-leader follower typology in the platoon is adopted to transmit global and local state information to agents. In the reward part, a new reward communication channel is proposed to solve the spurious reward and ``lazy agent'' problems in some existing multiagent RLs. Moreover, a curriculum learning approach is adopted to reduce crashes and speed up training. To validate the proposed strategy for platoon control, two existing multiagent RLs and a traditional platoon control strategy were applied in the same scenarios for comparison. Results showed that the CommPPO algorithm gained more rewards and achieved the largest fuel consumption reduction (11.6%).

19.
Chemistry ; 27(30): 8040-8047, 2021 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-33904607

RESUMO

6-Cyano-7-aminoquinoline (6CN-7AQ) and 3-cyano-7-aminoquinoline (3CN-7AQ) were synthesized and found to exhibit intense emission with quantum yield as high as 63 % and 85 %, respectively, in water. Conversely, their derivatives 6-cyano-7-azidoquinoline (6CN-7N3 Q) and 3-cyano-7-azidoquinoline (3CN-7N3 Q) show virtually no emission, which makes them suitable to be used as recognition agents in azide reactions based on fluorescence recovery. Moreover, conjugation of 6CN-7AQ with a hydrophobic biomembrane-penetration peptide PFVYLI renders a nearly non-emissive 6CN-7AQ-PFVYLI composite, which can be digested by proteinase K, recovering the highly emissive 6CN-7AQ with ∼200-fold enhancement. The result provides an effective early confirmation for RT-qPCR in viral detection.

20.
Accid Anal Prev ; 154: 106093, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33770719

RESUMO

Applications of neuroimaging methods have substantially contributed to the scientific understanding of human factors during driving by providing a deeper insight into the neuro-cognitive aspects of driver brain. This has been achieved by conducting simulated (and occasionally, field) driving experiments while collecting driver brain signals of various types. Here, this sector of studies is comprehensively reviewed at both macro and micro scales. At the macro scale, bibliometric aspects of these studies are analysed. At the micro scale, different themes of neuroimaging driving behaviour research are identified and the findings within each theme are synthesised. The surveyed literature has reported on applications of four major brain imaging methods. These include Functional Magnetic Resonance Imaging (fMRI), Electroencephalography (EEG), Functional Near-Infrared Spectroscopy (fNIRS) and Magnetoencephalography (MEG), with the first two being the most common methods in this domain. While collecting driver fMRI signal has been particularly instrumental in studying neural correlates of intoxicated driving (e.g. alcohol or cannabis) or distracted driving, the EEG method has been predominantly utilised in relation to the efforts aiming at development of automatic fatigue/drowsiness detection systems, a topic to which the literature on neuro-ergonomics of driving particularly has shown a spike of interest within the last few years. The survey also reveals that topics such as driver brain activity in semi-automated settings or neural activity of drivers with brain injuries or chronic neurological conditions have by contrast been investigated to a very limited extent. Potential topics in driving behaviour research are identified that could benefit from the adoption of neuroimaging methods in future studies. In terms of practicality, while fMRI and MEG experiments have proven rather invasive and technologically challenging for adoption in driving behaviour research, EEG and fNIRS applications have been more diverse. They have even been tested beyond simulated driving settings, in field driving experiments. Advantages and limitations of each of these four neuroimaging methods in the context of driving behaviour experiments are outlined in the paper.


Assuntos
Acidentes de Trânsito , Encéfalo , Eletroencefalografia , Humanos , Magnetoencefalografia , Neuroimagem
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