Proprioceptive External Torque Learning for Floating Base Robot and its Applications to Humanoid Locomotion

The estimation of external joint torque and contact wrench is essential for achieving stable locomotion of humanoids and safety-oriented robots. Although the contact wrench on the foot of humanoids can be measured using a force-torque sensor (FTS), FTS increases the cost, inertia, complexity, and failure possibility of the system. This paper introduces a method for learning external joint torque solely using proprioceptive sensors (encoders and IMUs) for a floating base robot. For learning, the GRU network is used and random walking data is collected. Real robot experiments demonstrate that the network can estimate the external torque and contact wrench with significantly smaller errors compared to the model-based method, momentum observer (MOB) with friction modeling. The study also validates that the estimated contact wrench can be utilized for zero moment point (ZMP) feedback control, enabling stable walking. Moreover, even when the robot's feet and the inertia of the upper body are changed, the trained network shows consistent performance with a model-based calibration. This result demonstrates the possibility of removing FTS on the robot, which reduces the disadvantages of hardware sensors. The summary video is available at https://youtu.be/gT1D4tOiKpo.Comment: Accepted by 2023 IROS conferenc

A Model Predictive Capture Point Control Framework for Robust Humanoid Balancing via Ankle, Hip, and Stepping Strategies

The robust balancing capability of humanoid robots against disturbances has been considered as one of the crucial requirements for their practical mobility in real-world environments. In particular, many studies have been devoted to the efficient implementation of the three balance strategies, inspired by human balance strategies involving ankle, hip, and stepping strategies, to endow humanoid robots with human-level balancing capability. In this paper, a robust balance control framework for humanoid robots is proposed. Firstly, a novel Model Predictive Control (MPC) framework is proposed for Capture Point (CP) tracking control, enabling the integration of ankle, hip, and stepping strategies within a single framework. Additionally, a variable weighting method is introduced that adjusts the weighting parameters of the Centroidal Angular Momentum (CAM) damping control over the time horizon of MPC to improve the balancing performance. Secondly, a hierarchical structure of the MPC and a stepping controller was proposed, allowing for the step time optimization. The robust balancing performance of the proposed method is validated through extensive simulations and real robot experiments. Furthermore, a superior balancing performance is demonstrated, particularly in the presence of disturbances, compared to a state-of-the-art Quadratic Programming (QP)-based CP controller that employs the ankle, hip, and stepping strategies. The supplementary video is available at https://youtu.be/CrD75UbYzdcComment: 19 pages,13 figure

Conditions for the differentiation of melanocyte-precursor cells from human cord blood-derived mesenchymal stem cells

The loss of skin pigmentation can induce compromised cutaneous immunity, which can result in conditions such as vitiligo. In this study, we evaluated various agents that are able to induce the differentiation of stem cells into melanocytes. We found that a mixture of forskolin (FK), stem cell factor (SCF) and endothelin-3 (EDN-3) induced melanocyte-like morphology in human cord blood-derived mesenchymal stem cells (CB-MSCs). In addition, significant expression of microphthalmia-associated transcription factor-M and tyrosinase-related protein-1 genes was observed. These results suggest that a mixture of FK, SCF and EDN-3 induces the differentiation of melanocyte-precursor cells (MPCs) from CB-MSCs.Keywords: mesenchymal stem cells, melanocyte-precursor cells, forskolin, microphthalmia-associated transcription factor-M, tyrosinase-related protein-1African Journal of Biotechnology Vol. 9(36), pp. 5975-5977, 6 September, 201

Gut microbiota, its role in induction of Alzheimer’s disease pathology, and possible therapeutic interventions: Special focus on anthocyanins

The human gut is a safe environment for several microbes that are symbiotic and important for the wellbeing of human health. However, studies on gut microbiota in different animals have suggested that changes in the composition and structure of these microbes may promote gut inflammation by releasing inflammatory cytokines and lipopolysaccharides, gut-wall leakage, and may affect systemic inflammatory and immune mechanisms that are important for the normal functioning of the body. There are many factors that aid in the gut’s dysbiosis and neuroinflammation, including high stress levels, lack of sleep, fatty and processed foods, and the prolonged use of antibiotics. These neurotoxic mechanisms of dysbiosis may increase susceptibility to Alzheimer’s disease (AD) and other neurodegenerative conditions. Therefore, studies have recently been conducted to tackle AD-like conditions by specifically targeting gut microbes that need further elucidation. It was suggested that gut dyshomeostasis may be regulated by using available options, including the use of flavonoids such as anthocyanins, and restriction of the use of high-fatty-acid-containing food. In this review, we summarize the gut microbiota, factors promoting it, and possible therapeutic interventions especially focused on the therapeutic potential of natural dietary polyflavonoid anthocyanins. Our study strongly suggests that gut dysbiosis and systemic inflammation are critically involved in the development of neurodegenerative disorders, and the natural intake of these flavonoids may provide new therapeutic opportunities for preclinical or clinical studies

Guidewire Breakage during Neurointerventional Procedures: a Report of Two Cases

We report on two cases of microguidewire breakage that occurred during endovascular treatment of intracranial aneurysms. The microguidewire can be broken when a part of the wire is stuck due to vascular tortuosity, and, subsequently, application of excessive rotational movement. The mechanical and physical properties of a microguidewire are also important factors in microguidewire breakage. We also suggest technical tips for avoidance of this problem

Antioxidant and neuroprotective effects of caffeine against Alzheimer's and Parkinson's disease: insight into the role of Nrf-2 and A2AR signaling

This paper reviews the results of studies conducted on the role of caffeine in the management of different neurological disorders, such as Parkinson's disease (PD) and Alzheimer's disease (AD). To highlight the potential role of caffeine in managing different neurodegenerative diseases, we identified studies by searching PubMed, Web of Science, and Google Scholar by scrutinizing the lists of pertinent publications. According to the collected overall findings, caffeine may reduce the elevated oxidative stress; inhibit the activation of adenosine A2A, thereby regulating the accumulation of Aβ; reduce the hyperphosphorylation of tau; and reduce the accumulation of misfolded proteins, such as α-synuclein, in Alzheimer's and Parkinson's diseases. The studies have suggested that caffeine has promising protective effects against different neurodegenerative diseases and that these effects may be used to tackle the neurological diseases and/or their consequences. Here, we review the ongoing research on the role of caffeine in the management of different neurodegenerative disorders, focusing on AD and PD. The current findings suggest that caffeine produces potent antioxidant, inflammatory, and anti-apoptotic effects against different models of neurodegenerative disease, including AD, PD, and other neurodegenerative disorders. Caffeine has shown strong antagonistic effects against the adenosine A2A receptor, which is a microglial receptor, and strong agonistic effects against nuclear-related factor-2 (Nrf-2), thereby regulating the cellular homeostasis at the brain by reducing oxidative stress, neuroinflammation, regulating the accumulation of α-synuclein in PD and tau hyperphosphorylation, amyloidogenesis, and synaptic deficits in AD, which are the cardinal features of these neurodegenerative diseases

Association between shift work and obesity among female nurses: Korean Nurses’ Survey

Background: Shift work has been hypothesized as a risk factor for obesity. In this study, we investigated the association between current shift work and body mass index (BMI) among female nurses in Korea. The relationship between duration of shift work and BMI of the participants was also evaluated. Methods: This cross-sectional survey evaluated participants in the Korean Nurses’ Survey, conducted from October to December 2011, using web-based self-administered questionnaires. A total of 9,989 nurses were included among 10,000 who registered on the survey web site (5,287 shift workers and 4,702 non-shift workers). Current shift workers were divided into tertiles of shift work duration (0.08–3.00 years, n = 1,732; 3.08–6.75 years, n = 1,731; and 6.83–38.00 years, n = 1,686). The BMI thresholds of overweight and obesity were ≥23 kg/m2 and ≥25 kg/m2, respectively. Data were analyzed using SPSS software. Results: Mean participant age was 33.2 ± 8.6 years and the mean BMI was 20.9 ± 2.5 kg/m2. There were statistically significant differences in current smoking status, regular drinking habit, dietary habits, regular exercise, sleep problems and self-perceived health status according to duration of shift work. The overall prevalence of overweight/obesity (18.6%) and obesity (7.4%) increased significantly as shift work duration increased from the lowest to highest tertile (P for trend <0.001). Multivariate logistic regression analysis revealed no association between current shift work and BMI. However, after adjusting for potential confounders, the participants with the longest duration of shift work were 1.63 (95% CI, 1.22–2.17) times more likely to be overweight or obese than those with the shortest duration. There was a significant positive association between obesity and shift work duration in the unadjusted analysis; however, it was attenuated and no longer significant in the multivariate model. Conclusions: The duration of shift work was positively associated with prevalence of overweight/obesity in nurses in Korea. Although these findings need to be confirmed in prospective studies, they suggest that special attention should be paid to female nurses with a long duration of shift work

Lack of prognostic significance for major adverse cardiac events of soluble suppression of tumorigenicity 2 levels in patients with ST-segment elevation myocardial infarction

Background: Elevation of soluble suppression of tumorigenicity 2 (sST2) is associated with cardiac fibrosis and hypertrophy. Under investigation herein, was whether sST2 level is associated with major adverse cardiac events (MACE) and left ventricular (LV) remodeling after primary percutaneous coronary intervention (PCI) in patients with acute ST-segment elevation myocardial infarction (STEMI). Methods: In total, this study included 184 patients who underwent successful primary PCI. A subsequent guideline-based medical follow-up was included (61.4 ± 11.8 years old, 85% male, 21% with Killip class ≥ I). sST2 concentration correlations with echocardiographic, angiographic, laboratory parameters, and clinical outcomes in STEMI patients were evaluated. Results: The median sST2 level was 60.3 ng/mL; 6 (3.2%) deaths occurred within 1 year. The sST2 level correlated with LV ejection fraction (LVEF) changes from baseline to 6 months (r= –0.273; p = 0.006) after adjustment for echocardiographic parameters including wall motions score index (WMSI). Recovery of LVEF at 6 months was highest in the tertile 1 group (Δ6 months – baseline LVEF; tertile 1, p = 0.001; tertile 2, p = 0.319; tertile 3, p = 0.205). The decrease in WMSI at 6 months was greater in the tertiles 1 and 2 groups than in the tertile 3 group (Δ6 months – baseline WMSI; tertile 1, p = 0.001; tertile 2, p = 0.013; tertile 3, p = 0.055). There was no association between sST2 levels and short-term (log rank p = 0.598) and long-term (p = 0.596) MACE. Conclusions: sST2 concentration have predictive value for LV remodeling on echocardiography in patients with STEMI who underwent primary PCI. However, sST2 concentration was not associated with short-term and long-term MACE

Calpains are Involved in Entamoeba histolytica-Induced Death of HT-29 Colonic Epithelial Cells

Entamoeba histolytica is an enteric tissue-invading protozoan parasite that can cause amebic colitis and liver abscess in humans. E. histolytica has the capability to kill colon epithelial cells in vitro; however, information regarding the role of calpain in colon cell death induced by ameba is limited. In this study, we investigated whether calpains are involved in the E. histolytica-induced cell death of HT-29 colonic epithelial cells. When HT-29 cells were co-incubated with E. histolytica, the propidium iodide stained dead cells markedly increased compared to that in HT-29 cells incubated with medium alone. This pro-death effect induced by ameba was effectively blocked by pretreatment of HT-29 cells with the calpain inhibitor, calpeptin. Moreover, knockdown of m- and µ-calpain by siRNA significantly reduced E. histolytica-induced HT-29 cell death. These results suggest that m- and µ-calpain may be involved in colon epithelial cell death induced by E. histolytica