System Design and Control Optimization for Neurorehabilitation Exoskeleton

Neurorehabilitation is a comprehensive approach aimed at helping patients regain motor control after a neural injury, including spinal cord injury, stroke, or other ischemic events. Early-stage neurorehabilitation is particularly delicate due to voluntary muscular weakness and lack of motor control, presenting in the form of spasticity. Unfortunately, this period of elevated weakness is when most neural control improvement can be made through a phenomenon called brain plasticity. Early rehabilitation traditionally requires a human therapist due to the adaptive and dynamic interpretation of undesired neuromuscular events. While efforts have been made to develop devices to aid in neurorehabilitation, the considerations that must be taken into account to design and develop an applicable, effective, and safe device can become a hindrance, preventing the proliferation of devices that could affect positive change in the communities that require them. Considerations for a neurorehabilitation device include sensor placement and usage, mechanical design, control system and design, physical interfacing, and user experience. In the following work, we first explore the physical design and development of an exoskeleton-type device, funded by the Department of Energy, that provides active assistive support to users and is therefore adaptable for early-stage neurorehabilitation patients. This device is capable of singular joint movement using a position-following controller with a manual interface. We employed serial elastic actuating modalities to stabilize displacement sensations and provided joint space feedback required for accurate displacement. We further include an analysis into control efficacy, wherein the average settling time for the position-based algorithm was of 2.02s, and the velocity algorithm performed at 3.04s. In terms of accuracy, the users were able to reach the desired positions within the 10 second time limit with 81% and 73% accuracy for the position control and velocity control, respectively. Following, we explore control mechanisms applicable to rehabilitative devices and define an admittance controller. We conclude parameterized control using biomechanical signals in an exoskeleton-type is viable, and including a feed-forward loop in the admittance controller provides the most coupled stability in the system following marginal analyses

Flexible system of multiple RGB-D sensors for measuring and classifying fruits in agri-food Industry

The productivity of the agri-food sector experiences continuous and growing challenges that make the use of innovative technologies to maintain and even improve their competitiveness a priority. In this context, this paper presents the foundations and validation of a flexible and portable system capable of obtaining 3D measurements and classifying objects based on color and depth images taken from multiple Kinect v1 sensors. The developed system is applied to the selection and classification of fruits, a common activity in the agri-food industry. Being able to obtain complete and accurate information of the environment, as it integrates the depth information obtained from multiple sensors, this system is capable of self-location and self-calibration of the sensors to then start detecting, classifying and measuring fruits in real time. Unlike other systems that use specific set-up or need a previous calibration, it does not require a predetermined positioning of the sensors, so that it can be adapted to different scenarios. The characterization process considers: classification of fruits, estimation of its volume and the number of assets per each kind of fruit. A requirement for the system is that each sensor must partially share its field of view with at least another sensor. The sensors localize themselves by estimating the rotation and translation matrices that allow to transform the coordinate system of one sensor to the other. To achieve this, Iterative Closest Point (ICP) algorithm is used and subsequently validated with a 6 degree of freedom KUKA robotic arm. Also, a method is implemented to estimate the movement of objects based on the Kalman Filter. A relevant contribution of this work is the detailed analysis and propagation of the errors that affect both the proposed methods and hardware. To determine the performance of the proposed system the passage of different types of fruits on a conveyor belt is emulated by a mobile robot carrying a surface where the fruits were placed. Both the perimeter and volume are measured and classified according to the type of fruit. The system was able to distinguish and classify the 95% of fruits and to estimate their volume with a 85% of accuracy in worst cases (fruits whose shape is not symmetrical) and 94% of accuracy in best cases (fruits whose shape is more symmetrical), showing that the proposed approach can become a useful tool in the agri-food industry.This project has been supported by the National Commission for Science and Technology Research of Chile (Conicyt) under FONDECYT grant 1140575 and the Advanced Center of Electrical and Electronic Engineering - AC3E (CONICYT/FB0008)

Influencia de los Gastos de campaña en los resultados de las elecciones federales de 1997

The concern for the control of the actual campaign expenses by the different political parties has been recently increased. It is argued that the excessive expenses cause inequity among the different political forces, since they strongly infl uence the citizen's decision to vote for the partisan option that spends more during the campaigns. The use of public resources for the fi nancing of these political campaigns has also been questioned. This study analyzes the incidence of the campaign expenses in the electoral results. The relationship betweaen the campaign expenses and the vote is statistically signifi cant, both the parties in its group explaining in some way the abstentionism and each one of the individual political forces, showing in a preliminary way the effi ciency in the use of these expenses. However, in both cases the estimated coeffi cients show a weak causal relationship

Role of Oxidative Stress as a Novel Therapeutic Target in Myocardial Injury Due to Ischemia/Reperfusion in Patients with Acute Myocardial Infarction

The most effective therapeutic intervention for reducing infarct size and improving outcomes in patients with acute myocardial infarction is the thrombolytic therapy or percutaneous coronary angioplasty. However, this process itself can generate ischemia-reperfusion injury that can be responsible for up to 50% of the final infarct size. Considering oxidative stress as the main damaging agent in this pathology, it has been postulated that reinforcing antioxidant defenses could improve cardiac function. However, up to date clinical trials based on monotherapies have been consistent in the favorable results. In this review the pathophysiological mechanisms of myocardial injury due to ischemia/reperfusion in patients undergoing percutaneous coronary angioplasty are updated. In addition, new therapeutic alternatives for cardioprotection in this population, are explored, with emphasis in the combined therapy as a novel antioxidant treatment for this myocardial injury

Regulation of stem cell dynamics through volume exclusion

Maintenance and regeneration of adult tissues rely on the self-renewal of stem cells. Regeneration without over-proliferation requires precise regulation of the stem cell proliferation and differentiation rates. The nature of such regulatory mechanisms in different tissues, and how to incorporate them in models of stem cell population dynamics, is incompletely understood. The critical birth-death (CBD) process is widely used to model stem cell populations, capturing key phenomena, such as population asymmetry and scaling laws in clone size distributions. However, the CBD process neglects regulatory mechanisms. Here, we propose the birth-death process with volume exclusion (vBD), a variation of the birth-death process that takes into account crowding effects, such as may arise due to limited space in a stem cell niche. While the deterministic rate equations predict a single non-trivial attracting steady state, the master equation predicts extinction and a transient distribution of stem cell numbers that can be bimodal. We investigate the accuracy of the system-size expansion (including finite size corrections to the linear-noise approximation), the quasi-steady state approximation, and the WKB method to approximate the probability distribution solution of the vBD master equation, as well as the mean extinction time. Our study suggests that the size distribution of a stem cell population and its extinction dynamics bear signatures that may be useful to detect negative feedback mediated via volume exclusion.Comment: 15 pages, 5 figure

CETA on investment: the definitive surrender of EU Law to GATS and NAFTA/BITs

Provisions on investment in the Comprehensive Economic and Trade Agreement (CETA) between Canada and the EU, both on substance and on dispute settlement procedures, culminate a long process of replacement of the original EECT/ECT approach to establishment by the approaches followed by the World Trade Organization (WTO) General Agreement on Trade in Services (GATS), the North American Free Trade Agreement (NAFTA) and Bilateral Investment Treaties (BITs). The article analyzes this process; it focuses in particular the law of external relations but takes into account the evolution of the law of the internal market and can also be read from this perspective as, in the authors’ opinion, the evolution in the former throws light on the latter. The article intends to leave the legal facts to speak by themselves. By unveiling their rationale, it also gives rise to political concerns regarding the evolution of the law. As CETA limits the ability of the EU to legislate and erodes the European Court of Justice’s role, the article leads to the conclusion that the underlying rationale for the evolution, both in the internal and the external areas, has not been that of promoting integration but that of deregulation

Sabi\'a: Portuguese Large Language Models

As the capabilities of language models continue to advance, it is conceivable that "one-size-fits-all" model will remain as the main paradigm. For instance, given the vast number of languages worldwide, many of which are low-resource, the prevalent practice is to pretrain a single model on multiple languages. In this paper, we add to the growing body of evidence that challenges this practice, demonstrating that monolingual pretraining on the target language significantly improves models already extensively trained on diverse corpora. More specifically, we further pretrain GPT-J and LLaMA models on Portuguese texts using 3% or less of their original pretraining budget. Few-shot evaluations on Poeta, a suite of 14 Portuguese datasets, reveal that our models outperform English-centric and multilingual counterparts by a significant margin. Our best model, Sabi\'a-65B, performs on par with GPT-3.5-turbo. By evaluating on datasets originally conceived in the target language as well as translated ones, we study the contributions of language-specific pretraining in terms of 1) capturing linguistic nuances and structures inherent to the target language, and 2) enriching the model's knowledge about a domain or culture. Our results indicate that the majority of the benefits stem from the domain-specific knowledge acquired through monolingual pretraining

Material didáctico y logros de aprendizajes en matemática de los estudiantes de una unidad educativa de Riobamba, 2022

El objetivo general de este trabajo de investigación fue el determinar la relación que existe entre el material didáctico y los logros de aprendizaje. En su metodología se aplicó el enfoque cuantitativo con un diseño no experimental de nivel correlacional, para lo cual fue necesario una muestra de 36 estudiantes de una unidad educativa de Riobamba, 2022. Dentro de los resultados obtenidos el coeficiente de correlación de Rho Spearman determinó que existe una relación positiva muy fuerte (0,984) en las variables abordadas en este estudio. En lo que respecta a sus conclusiones se establece que existe relación entre el material didáctico y el bloque de algebra y funciones además del estadístico y probabilidad