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STUDY OBJECTIVES: To investigate the cost-effectiveness of cognitive behavioral therapy for insomnia (CBTI), with an additional focus on digital CBTI (dCBTI) in adults with insomnia. METHODS: We searched eight electronic databases for economic evaluations of CBTI: PubMed, Scopus, Web of Science, psycINFO, Cochrane, Library, CINAHL, ProQuest, and National Health Service Economic Evaluation Database. Meta-analyses were performed to investigate the effects and costs between CBTI and control groups (no treatment, other treatments included hygiene education and treatment as usual). Subgroup analyses for dCBTI were conducted. RESULTS: Twelve randomized controlled trial studies between 2004 and 2023 were included in our systematic review and meta-analyses. The incremental cost-utility ratios and incremental cost-effectiveness ratios showed that the CBTI and dCBTI groups were more cost-effective than controls, from healthcare perspective and societal perspective, respectively. Compared to controls, CBTI demonstrated significantly better efficacy within 12 months. Healthcare costs were significantly higher in the CBTI groups compared to the controls within 6 months but there was no difference at 12 months. Additionally, dCBTI was associated with significantly lower presenteeism costs compared to controls at 6 months. CONCLUSIONS: Our findings suggest that CBTI is more cost-effective than other treatments or no treatment for adults with insomnia. It may bring more economic benefits in the long term, especially in long-lasting efficacy and cost reduction. In addition, dCBTI is one of the cost-effective options for insomnia. PROSPERO REGISTRATION NUMBER: CRD42â 022â 383â 440. URL: www.crd.york.ac.uk/PROSPERO. NAME FOR PROSPERO REGISTRATION: Cost-effectiveness of cognitive behavioral therapy for insomnia (CBTI): a systematic review with meta-analysis.
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Terapia Cognitivo-Comportamental , Análise Custo-Benefício , Distúrbios do Início e da Manutenção do Sono , Humanos , Distúrbios do Início e da Manutenção do Sono/terapia , Distúrbios do Início e da Manutenção do Sono/economia , Terapia Cognitivo-Comportamental/economia , Terapia Cognitivo-Comportamental/métodos , Custos de Cuidados de Saúde/estatística & dados numéricosRESUMO
Depression is one of the most common forms of psychopathology, which is associated with gut microbiota dysfunction. Dihydroartemisinin (DHA) has been shown to regulate gut microbiota and ameliorate neuropathies, but whether it can be used to treat depression remains unclear. Our study found that DHA treatment raised the preference for sugar water in chronic unpredictable mild stress (CUMS)-induced mice and reduced the immobility time in open field, forced swimming and tail suspension experiments, and promoted doublecortin expression. Additionally, DHA up-regulated the diversity and richness of intestinal microbiota in depression-like mice, and restored the abnormal abundance of microbiota induced by CUMS, such as Turicibacter, Lachnospiraceae, Erysipelotrichaceae, Erysipelatoclostridium, Eubacterium, Psychrobacter, Atopostipes, Ileibacterium, Coriobacteriacea, Alistipes, Roseburia, Rikenella, Eggerthellaceae, Ruminococcus, Tyzzerella, and Clostridia. Furthermore, KEGG pathway analysis revealed that gut microbiota involved in the process of depression may be related to glucose metabolism, energy absorption and transport, and AMPK signaling pathway. These results indicated that DHA may play a protective role in CUMS-induced depression by mediating gut-microbiome.
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Artemisininas , Depressão , Microbioma Gastrointestinal , Estresse Psicológico , Animais , Microbioma Gastrointestinal/efeitos dos fármacos , Depressão/tratamento farmacológico , Depressão/metabolismo , Camundongos , Masculino , Artemisininas/farmacologia , Estresse Psicológico/metabolismo , Estresse Psicológico/complicações , Camundongos Endogâmicos C57BL , Comportamento Animal/efeitos dos fármacos , Antidepressivos/farmacologia , Modelos Animais de DoençasRESUMO
In this paper, a new approach involving the use of a mobile manipulator to assist humans with mobility impairments to walk is proposed. First, in order to achieve flexible interaction between humans and mobile manipulators, we propose a variable admittance controller that can adaptively regulate the virtual mass and damping parameters based on the interaction forces and the human motion intention predicted using the fuzzy theory. Moreover, a feedforward velocity compensator based on a designed state observer is proposed to decrease the inertia resistance of the manipulator, effectively enhancing the compliance of the human-robot interaction. Then, the configuration of the mobile manipulator is optimized based on a null-space approach by considering the singularity, force capacity, and deformation induced by gravity. Finally, the proposed assisted walking approach for the mobile manipulator is implemented using the human-robot interaction controller and the null-space controller. The validity of the proposed controllers and the feasibility of assisted human walking are verified by conducting a set of tests involving different human volunteers.
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Many rehabilitation exoskeletons have been used in the field of stroke rehabilitation. Generating human-like motion is necessary for exoskeletons to help patients perform activities of daily living (ADL) while maintaining interaction quality and ergonomics. However, most of the current motion generation algorithms utilize inverse kinematics (IK) to solve the final configuration before generation, and do not consider the movement of shoulder girdle. Separately considering the shoulder girdle motion and arm motion, this paper proposes an algorithm integrated IK to generate human-like motion. The arm moves towards the target with a bell-shaped velocity in the absence of the final configuration, and the shoulder girdle maintain natural passive motion. Moreover, the generated motion can be mapped to the configuration space of exoskeletons. Compared with the experimental data collected using a motion capture system, the values of RMSE and HPDI of the generated wrist trajectory in the task space are within 0.2 and 0.17, respectively, while those of RMSE in the joint space are within 15 deg, which demonstrates the human-like nature of the generated motion.
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Exoesqueleto Energizado , Ombro , Humanos , Braço , Atividades Cotidianas , Extremidade Superior , Algoritmos , Movimento , Fenômenos Biomecânicos , Articulação do PunhoRESUMO
Depression is a common mental illness. Ferroptosis is a form of cell death that may be responsible for neurological disease, but the role of ferroptosis in depression remains unclear. tRNA-derived small RNA (tsRNA) is an emerging non-coding small RNA, making it an important medium for studying neurological diseases. Chronic unpredictable mild stress (CUMS) was used to construct the depression model in mice, which was treated with ferrostatin-1 (Fer-1). Classical behavioral test, immunofluorescence and small RNA sequencing were used to detect depression-like behaviors, neuronal proliferation and the expression profile of tsRNAs in mice, respectively. The primary neuronal cell damage model was constructed by corticosterone (CORT), and the function of key tsRNA was investigated by quantitative real-time PCR, western blot and CCK-8 assays. Here, Fer-1 reduced the depression-like behavior of CUMS-induced mice and promoted neuronal growth. In addition, CUMS caused the disorder of tsRNA expression profile in hippocampal tissues of mice, and Fer-1 alleviated the abnormal tsRNA expression, among which tsRNA-3029b was an effective target. In vitro experiments manifested that ROS accumulation and decreased expression of SLC7A11 and GPX4 were found in CORT-induced depression-like cell model, suggesting that ferroptosis was involved in neuronal injury. However, inhibition of tsRNA-3029b suppressed neuronal cell ferroptosis and facilitated neuronal regeneration. In conclusion, Fer-1 showed an antidepressant effect in CUMS-induced mice and alleviated the abnormal expression profile of tsRNA. tsRNA-3029b was a key target in depression, and silencing of tsRNA-3029b reduced the occurrence of ferroptosis and protected neurons from injury, which may provide novel target for the treatment of depression.
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Transtorno Depressivo , Ferroptose , Camundongos , Animais , Depressão/tratamento farmacológico , Depressão/metabolismo , Transtorno Depressivo/tratamento farmacológico , Antidepressivos/farmacologia , Antidepressivos/uso terapêutico , RNA/farmacologia , RNA/uso terapêuticoRESUMO
Modeling and motion extraction of human upper limbs are essential for interpreting the natural behavior of upper limb. Owing to the high degrees of freedom (DOF) and highly dynamic nature, existing upper limb modeling methods have limited applications. This study proposes a generic modeling and motion extraction method, named Primitive-Based triangular body segment method (P-BTBS), which follows the physiology of upper limbs, allows high accuracy of motion angles, and describes upper-limb motions with high accuracy. For utilizing the upper-limb modular motion model, the motion angles and bones can be selected as per the research topics (The generic nature of the study targets). Additionally, P-BTBS is suitable in most scenarios for estimating spatial coordinates (The generic nature of equipment and technology). Experiments in continuous motions with seven DOFs and upper-limb motion description validated the excellent performance and robustness of P-BTBS in extracting motion information and describing upper-limb motions, respectively. P-BTBS provides a new perspective and mathematical tool for human understanding and exploration of upper-limb motions, which theoretically supports upper-limb research.
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Medicamentos Genéricos , Tecnologia , Humanos , Movimento (Física) , Extremidade SuperiorRESUMO
Primary tumor resection for metastatic breast cancer (MBC) has demonstrated a survival advantage, however, not all patients with MBC benefit from surgery. The purpose of this study was to develop a predictive model to select patients with MBC who are most likely to benefit from surgery at the primary site. Data from patients with MBC were obtained from the Surveillance, Epidemiology and End Results (SEER) cohort and patients treated at the Yunnan Cancer Hospital. The patients from the SEER database were divided into surgery and non-surgery groups and a 1:1 propensity score matching (PSM) was used to balance baseline characteristics. We hypothesized that patients who underwent local resection of primary tumors had improved overall survival (OS) compared to those who did not undergo surgery. Based on the median OS time of the non-surgery group, patients from the surgery group were further categorized into beneficial and non-beneficial groups. Logistic regression analysis was performed to identify independent factors associated with improved survival in the surgery group and a nomogram was established using the most significant predictive factors. Finally, internal and external validation of the prognostic nomogram was also evaluated by concordance index (C-index) and using a calibration curve. A total of 7759 eligible patients with MBC were identified in the SEER cohort and 92 with MBC patients who underwent surgery at the Yunnan Cancer Hospital. Amongst the SEER cohort, 3199 (41.23%) patients received surgery of the primary tumor. After PSM, the OS between the surgery and non-surgery group was significantly different based on Kaplan-Meier survival analysis (46 vs. 31 months, P < 0.001), In the surgery group, 562 (55.20%) patients survived for longer than 31 months and were classified in the beneficial group. Significant differences were observed in patient characteristics between the beneficial and non-beneficial groups including age, grade, tumor size, liver metastasis, breast cancer subtype and marital status. These factors were used as independent predictors to create a nomogram. The internally and externally validated C-indices of the nomogram were 0.703 and 0.733, respectively, indicating strong consistency between the actual and predicted survival. A nomogram was developed and used to identify MBC patients who are most likely to benefit from primary tumor resection. This predictive model has the potential to improve clinical decision-making and should be considered routine clinical practice.
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Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/cirurgia , Neoplasias da Mama/patologia , China/epidemiologia , Prognóstico , Nomogramas , Estimativa de Kaplan-MeierRESUMO
BACKGROUND: Depressed patients suffered from severe psychological distress even after the first COVID-19 outbreak was initially controlled. The longitudinal changes and associations among stress and other psychological problems during this period remained unknown. In this study we investigated stress symptoms and the longitudinal impact of stress symptoms on other psychological symptoms in depressed patients after the first COVID-19 outbreak was initially controlled. METHODS: A total of 5241 depressed patients at the outpatients of 56 hospitals across mainland China were recruited from May 18 to June 18, 2020. Five months later, 2113 of them responded again. Demographic characteristics were collected and psychological symptoms were evaluated at baseline and the follow-up. The longitudinal associations between stress symptoms at baseline and the changes of other psychological problems were assessed using Poisson regression. RESULTS: The prevalence of stress symptoms, depressive symptoms, anxiety symptoms and insomnia symptoms declined over time. Having stress symptoms at baseline was positively associated with the new occurrences of depressive symptoms, anxiety symptoms and insomnia symptoms (range, adjusted RRs 1.69-1.81). LIMITATIONS: The sampling method and the high dropout rate are the major limitations. Additionally, the mental conditions of the participants were not obtained, which may lead to unavoidable bias. CONCLUSIONS: The prevalence of stress symptoms declined over time after the first COVID-19 outbreak was initially controlled. We found that having stress symptoms at baseline was a predictor for the new occurrences of depressive symptoms, anxiety symptoms and insomnia symptoms.
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COVID-19 , Distúrbios do Início e da Manutenção do Sono , Ansiedade/epidemiologia , Ansiedade/psicologia , COVID-19/epidemiologia , China/epidemiologia , Depressão/epidemiologia , Depressão/psicologia , Surtos de Doenças , Humanos , Estudos Prospectivos , SARS-CoV-2 , Distúrbios do Início e da Manutenção do Sono/epidemiologiaRESUMO
Continuous passive motion (CPM) machines are commonly used after various knee surgeries, but information on tibiofemoral forces (TFFs) during CPM cycles is limited. This study aimed to explore the changing trend of TFFs during CPM cycles under various ranges of motion (ROM) and body weights (BW) by establishing a two-dimensional mathematical model. TFFs were estimated by using joint angles, foot load, and leg−foot weight. Eleven healthy male participants were tested with ROM ranging from 0° to 120°. The values of the peak TFFs during knee flexion were higher than those during knee extension, varying nonlinearly with ROM. BW had a significant main effect on the peak TFFs and tibiofemoral shear forces, while ROM had a limited effect on the peak TFFs. No significant interaction effects were observed between BW and ROM for each peak TFF, whereas a strong linear correlation existed between the peak tibiofemoral compressive forces (TFCFs) and the peak resultant TFFs (R2 = 0.971, p < 0.01). The proposed method showed promise in serving as an input for optimizing rehabilitation devices.
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Pé , Articulação do Joelho , Fenômenos Biomecânicos , Humanos , Joelho , Masculino , Amplitude de Movimento Articular , Estresse MecânicoRESUMO
Objective: This study aimed to investigate the chronotypes and their relationship with sleep disturbances and mental distress among college students. Methods: Students from a university in Guangzhou, China, were recruited through a cross-sectional online survey. Data were collected by self-reported questionnaires including socio-demographics, lifestyles and health conditions, sleep patterns on weekdays and weekends, as well as the reduced Morningness-Eveningness Questionnaire (rMEQ), the Insomnia Severity Index, the Epworth Sleepiness Scale, the Beck Depression Inventory-13, and the Zung Self-Rating Anxiety Scale. Multivariate analyses were performed to examine the associations of chronotypes with sleep compensation, sleep disturbances, and mental distress. Results: A total of 1,607 questionnaires were received, among which 1,569 (97.6%) were valid for further analysis. Among these participants [mean age 19.86 ± 1.16 (15-27) years], morning types (M-types), intermediate types (I-types), and evening types (E-types) accounted for 14.9, 71.5, and 13.6%, respectively. The regression analysis revealed that E-types were positively associated with long sleep compensation on weekends (adjusted OR 2.443, 95%CI 1.740-3.429) compared with I-types, while M-types were the opposite (adjusted OR 0.623, 95%CI 0.392-0.990). E-types were also positively correlated with insomnia symptoms (adjusted OR 2.000, 95%CI 1.428-2.801), depressive symptoms (adjusted OR 2.068, 95%CI 1.496-2.858), and anxiety symptoms (adjusted OR 2.188, 95%CI 1.387-3.451). However, no significant association was found between chronotypes and excessive daytime sleepiness. Conclusion: Our study found that E-types were associated with long sleep compensation on weekends and insomnia, depression, and anxiety symptoms. Our findings emphasized the importance of early recognition and intervention of E-types and their accompanied sleep problems and mental distress.
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Previous studies have shown that marital status can affect the overall survival (OS) of cancer patients yet its role in metastatic pancreatic ductal adenocarcinoma (mPDAC) remains unclear. This study aimed to explore the impact of marital status on the OS of mPDAC patients and to construct a prognostic nomogram to predict OS outcomes. Data from patients diagnosed with mPDAC were obtained from the Surveillance, Epidemiology, and End Results database between 1973 and 2015. The patients were randomized into primary and validation cohorts. Kaplan-Meier survival analysis was performed to compare differences in survival depending on marital status. Univariate and multivariate analyses were conducted to identify independent prognostic factors and a nomogram was established based using Cox regression analyses. Validation of the prognostic nomogram was evaluated with a calibration curve and concordance index (C-index). Our data showed significant differences in the OS of mPDAC patients with different marital status by Kaplan-Meier analysis (P < 0.05). Univariate and multivariate analyses confirmed that marital status was an independent OS-related factor in mPDAC patients. Based on the multivariate models of the primary cohort, a nomogram was developed that combined marital status, age, grade, tumor size, surgery of primary site, surgery of lymph node and metastatic. The nomogram showed that marital status had a moderate influence on predicting the OS of mPDAC patients. Moreover, the internally and externally validated C-indexes were 0.633 and 0.619, respectively. A calibration curve confirmed favorable consistency between the observed and predicted outcomes. Marital status was identified as an independent prognostic factor for OS of mPDAC patients and is a reliable and valid parameter to predict the survival of patients with mPDAC. This prognostic model has value and may be integrated as a tool to inform decision-making in the clinic.
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Adenocarcinoma , Nomogramas , Fatores Etários , Humanos , Estado Civil , Estadiamento de Neoplasias , Neoplasias Pancreáticas , Prognóstico , Programa de SEER , Neoplasias PancreáticasRESUMO
INTRODUCTION: The prevalence rate and related factors of insomnia remained unknown after the COVID-19 epidemic had been under control. Therefore, we conducted this survey to investigate the prevalence rate and related factors of insomnia symptoms in the Chinese general public after the COVID-19 had been initially control. METHODS: An online survey was conducted among Chinese citizens through the JD Health APP. The questionnaire was used for collecting demographic data and self-designed questions related to the COVID-19 outbreak. Insomnia Severity Index, Patient Health Questionnaire-9, Somatic Symptom Scale-8 and Impact of Events Scale-Revised were used for measuring psychological symptoms. To examine the associations of sociodemographic and psychological factors with insomnia symptoms, a binary logistic regression was used. RESULTS: In total, there were 14,894 eligible participants, and 4601 (30.9%) participants were found to have insomnia symptoms. The regression model revealed that a higher risk of insomnia symptoms was associated with being over the age of 40 years, having history of psychiatric disorders, smoking, having infected friends or colleagues, having depressive or somatic symptoms, experiencing psychological distress and feeling estranged from family members. Meanwhile a lower risk of insomnia symptoms was associated with being female, having closer family relationships, not feeling alienated from others and being satisfied with the available information. CONCLUSION: In our study, 30.9% of the participants in the general public reported insomnia symptoms after the COVID-19 epidemic had been initially controlled. When providing precise interventions for insomnia, extra attention should be paid to the individuals who are male, elderly and smokers, and those with psychiatric disorder history, with infected friends or colleagues, with psychological symptoms and with poor social support.
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The prevalence and related factors of mental health impact among medical staffs who experienced the second wave of the COVID-19 pandemic in China is unknown. Therefore, this survey was conducted to investigate the prevalence and related factors of depressive, anxiety, acute stress, and insomnia symptoms in medical staffs in Kashi, Xinjiang, China during the second wave of the COVID-19 pandemic. A cross-sectional online survey was conducted among medical staffs working in First People's Hospital of Kashi, Xinjiang. The questionnaire collected demographic data and self-design questions related to the COVID-19 pandemic. The Impact of Events Scale-6, the Insomnia Severity Index, the Patient Health Questionnaire-9, the Generalized Anxiety Disorder Scale-7, the Perceived Social Support Scale, the Chinese Big Five Personality Inventory-15, and the Trait Coping Style Questionnaire were used to measure psychological symptoms or characteristics. Binary logistic regression was carried out to examine the associations between socio-demographic factors and symptoms of depression, anxiety, stress, and insomnia. In total, data from 123 participants were finally included, among which the prevalence rate of depressive, anxiety, acute stress, and insomnia symptoms is 60.2, 49.6, 43.1, and 41.1%, respectively. The regression model revealed that minority ethnicity, being worried about infection, spending more time on following pandemic information, and neurotic personality were positively associated with the mental health symptoms, while extraversion personality, higher education level, and better social support were negatively associated. In our study, the prevalence of mental health impact was high among medical staffs in Kashi, China who experienced the second wave of the COVID-19 pandemic. Several factors were found to be associated with mental health conditions. These findings could help identify medical staffs at risk for mental health problems and be helpful for making precise mental health intervention policies during the resurgence. Our study may pave way for more research into Xinjiang during the COVID-19 pandemic.
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COVID-19 , Distúrbios do Início e da Manutenção do Sono , Ansiedade/epidemiologia , China/epidemiologia , Estudos Transversais , Depressão/epidemiologia , Humanos , Corpo Clínico , Pandemias , Prevalência , SARS-CoV-2 , Distúrbios do Início e da Manutenção do Sono/epidemiologiaRESUMO
The calibration problem of binocular stereo vision rig is critical for its practical application. However, most existing calibration methods are based on manual off-line algorithms for specific reference targets or patterns. In this paper, we propose a novel simultaneous localization and mapping (SLAM)-based self-calibration method designed to achieve real-time, automatic and accurate calibration of the binocular stereo vision (BSV) rig's extrinsic parameters in a short period without auxiliary equipment and special calibration markers, assuming the intrinsic parameters of the left and right cameras are known in advance. The main contribution of this paper is to use the SLAM algorithm as our main tool for the calibration method. The method mainly consists of two parts: SLAM-based construction of 3D scene point map and extrinsic parameter calibration. In the first part, the SLAM mainly constructs a 3D feature point map of the natural environment, which is used as a calibration area map. To improve the efficiency of calibration, a lightweight, real-time visual SLAM is built. In the second part, extrinsic parameters are calibrated through the 3D scene point map created by the SLAM. Ultimately, field experiments are performed to evaluate the feasibility, repeatability, and efficiency of our self-calibration method. The experimental data shows that the average absolute error of the Euler angles and translation vectors obtained by our method relative to the reference values obtained by Zhang's calibration method does not exceed 0.5Ë and 2 mm, respectively. The distribution range of the most widely spread parameter in Euler angles is less than 0.2Ë while that in translation vectors does not exceed 2.15 mm. Under the general texture scene and the normal driving speed of the mobile robot, the calibration time can be generally maintained within 10 s. The above results prove that our proposed method is reliable and has practical value.
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As the aging of the population becomes more severe, wheelchair-mounted robotic arms (WMRAs) are gaining an increased amount of attention. Laser pointer interactions are an attractive method enabling humans to unambiguously point out objects and pick them up. In addition, they bring about a greater sense of participation in the interaction process as an intuitive interaction mode. However, the issue of humanâ»robot interactions remains to be properly tackled, and traditional laser point interactions still suffer from poor real-time performance and low accuracy amid dynamic backgrounds. In this study, combined with an advanced laser point detection method and an improved pose estimation algorithm, a laser pointer is used to facilitate the interactions between humans and a WMRA in an indoor environment. Assistive grasping using a laser selection consists of two key steps. In the first step, the images captured using an RGB-D camera are pre-processed, and then fed to a convolutional neural network (CNN) to determine the 2D coordinates of the laser point and objects within the image. Meanwhile, the centroid coordinates of the selected object are also obtained using the depth information. In this way, the object to be picked up and its location are determined. The experimental results show that the laser point can be detected with almost 100% accuracy in a complex environment. In the second step, a compound pose-estimation algorithm aiming at a sparse use of multi-view templates is applied, which consists of both coarse- and precise-matching of the target to the template objects, greatly improving the grasping performance. The proposed algorithms were implemented on a Kinova Jaco robotic arm, and the experimental results demonstrate their effectiveness. Compared with commonly accepted methods, the time consumption of the pose generation can be reduced from 5.36 to 4.43 s, and synchronously, the pose estimation error is significantly improved from 21.31% to 3.91%.
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Braço , Robótica/instrumentação , Cadeiras de Rodas , Algoritmos , Força da Mão , Humanos , LasersRESUMO
To characterize the size distribution of water soluble inorganic ions (WSâ ¡) in haze days, particle samples were collected by an Andersen cascade impactor in Shijiazhuang from October 15 to November 14 in 2013, and the concentrations of eight kinds of WSâ ¡ (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-and SO42-) during a typical haze episode were analyzed by ion chromatography. Sources and formation mechanism of WSâ ¡ were analyzed based on their size distributions. The results showed that Shijiazhuang suffers serious air pollution during the autumn season. The daily average concentrations of PM10and PM2.5were (361.2±138.7) µg·m-3 and (175.6±87.2) µg·m-3 and the daily average concentration of PM2.5was 2.3 times as high as the national secondary standard. The total water soluble inorganic ion concentrations (TWSâ ¡) in clean days, light haze days and heavy haze days were(64.4±4.6)µg·m-3, (109.9±22.0)µg·m-3 and (212.9±50.1) µg·m-3 respectively. In addition, the ratio of secondary inorganic ions (SNA:SO42-, NO3- and NH4+) in TWSâ ¡ increased from 44.9% to 77.6% as changed from clean days to the heavy haze days, suggesting the evolution of haze episodes mainly originated from the formation and accumulation of SNA. The size distributions of SO42-, NO3- and NH4+ were bimodal in clean days, peaking at 0.43 -0.65 µm and 4.7-5.8 µm, respectively, which changed to unimodal distribution in both the light and heavy haze days, peaking at 0.65-1.1 µm. Owing to high humidity during the heavy haze days, the aqueous phase reactions of SO42- and NO3- were likely promoted, which led to the transformation of condensation mode in clean days to the droplet mode in haze days. The size distributions of Na+, Mg2+ and Ca2+ were different with that of SNA, which showed a coarse mode peaking at 4.7-5.8 µm both in clean and haze days, whereas K+and Cl- showed a bimodal distribution both in clean and haze days, although the modal size was different in clean and haze days.