Application research of master-slave cranio-maxillofacial surgical robot based on force feedback

Background: The complex anatomical structure, limited field of vision, and easily damaged nerves, blood vessels, and other anatomical structures are the main challenges of a cranio-maxillofacial (CMF) plastic surgical robot. Bearing these characteristics and challenges in mind, this paper presents the design of a master-slave surgical robot system with a force feedback function to improve the accuracy and safety of CMF surgery. Methods: A master-slave CMF surgical robot system based on force feedback is built with the master tactile robot and compact slave robot developed in the laboratory. Model-based master robot gravity compensation and force feedback mechanism is used for the surgical robot. Control strategies based on position increment control and ratio control are adopted. Aiming at the typical mandibular osteotomy in CMF surgery, a scheme suitable for robot-assisted mandibular osteotomy is proposed. The accuracy and force feedback function of the robot system under direct control and master-slave motion modes are verified by experiments. Results: The drilling experiment of the mandible model in direct control mode shows that the average entrance point error is 1.37 ± 0.30 mm, the average exit point error is 1.30 ± 0.25 mm, and the average posture error is 2.27° ± 0.69°. The trajectory tracking and in vitro experiment in the master-slave motion mode show that the average position following error is 0.68 mm, and the maximum force following error is 0.586 N, achieving a good tracking and force feedback function. Conclusion: The experimental results show that the designed master-slave CMF robot can assist the surgeon in completing accurate mandibular osteotomy surgery. Through force feedback mechanism, it can improve the interaction between the surgeon and the robot, and complete tactile trajectory movements.

The impact of vaccination on the evolution of COVID-19 in Portugal

<abstract><p>In this work we use simple mathematical models to study the impact of vaccination against COVID-19 in Portugal. First, we fit a SEIR type model without vaccination to the Portuguese data on confirmed cases of COVID-19 by the date of symptom onset, from the beginning of the epidemic until the 23rd January of 2021, to estimate changes in the transmission intensity. Then, by including vaccination in the model we develop different scenarios for the fade-out of the non pharmacological intervention (NPIs) as vaccine coverage increases in the population according to Portuguese vaccination goals. We include a feedback function to mimic the implementation and relaxation of NPIs, according to some disease incidence thresholds defined by the Portuguese health authorities.</p></abstract>

From Combined to Hybrid: Making Feedback-based AE even Smaller

In CHES 2017, Chakraborti et al. proposed COFB, a rate-1 sequential block cipher-based authenticated encryption (AE) with only 1.5n-bit state, where n denotes the block size. They used a novel approach, the so-called combined feedback, where each block cipher input has a combined effect of the previous block cipher output and the current plaintext block. In this paper, we first study the security of a general rate-1 feedback-based AE scheme in terms of its overall internal state size. For a large class of feedback functions, we show that the overlying AE scheme can be attacked in 2r queries if the internal state size is n + r bits for some r ≥ 0. This automatically shows that a birthday bound (i.e. 2n/2 queries) secure AE scheme must have at least 1.5n-bit state, whence COFB is almost-optimal (use 1.5n-bit state and provides security up to 2n/2/n queries). We propose a new feedback function, called the hybrid feedback or HyFB, which is a hybrid composition of plaintext and ciphertext feedbacks. HyFB has a key advantage of lower XOR counts over the combined feedback function. This essentially helps in reducing the hardware footprint. Based on HyFB we propose a new AE scheme, called HyENA, that achieves the state size, rate, and security of COFB. In addition, HyENA has significantly lower XOR counts as compared to COFB, whence it is expected to have a smaller implementation as compared to COFB.

EFFECTS OF FEEDBACK NN SKILLS DURING CARDIOPULMONAL REANIMATION TRAINING

Sudden cardiac arrest is one of the main causes of death in Europe. Early initiation and qualitative performance of cardiopulmonary resuscitation can reduce mortality. In order to perform cardio-pulmonary resuscitation of appropriate quality, theoretical and practical knowledge is needed which can be improved by clinical simulation. The aim of the study was to find out the effect of feedback on participants' skills during cardiopulmonary resuscitation training. Hypothesis - feedback improves participants' skills during cardiopulmonary resuscitation training. Research Method - randomized controlled simulation study. Research instruments - observation protocol, questionnaire. A total of 32 employees of State Emergency Medical Service (medical practitioners) participated in the study. The hypothesis was confirmed - feedback improves participants' skills during cardiopulmonary resuscitation training. The total evaluation of cardiopulmonary resuscitation in the intervention group, which performed the cardiopulmonary resuscitation scenario with the feedback function is higher (92,13%) compared to the control group (77%). Most of the participants in the intervention group fully agree that the use of feedback function during training improves the overall cardiopulmonary resuscitation skills. The results of the study indicate that the development of cardiopulmonary resuscitation training programs for medical students and practitioners requires the inclusion of practical activities with clinical simulations with feedback.

Human free-operant performance varies with a concurrent task: Probability learning without a task, and schedule-consistent with a task

Three experiments examined human rates and patterns of responding during exposure to various schedules of reinforcement with or without a concurrent task. In the presence of the concurrent task, performances were similar to those typically noted for nonhumans. Overall response rates were higher on medium-sized ratio schedules than on smaller or larger ratio schedules (Experiment 1), on interval schedules with shorter than longer values (Experiment 2), and on ratio compared with interval schedules with the same rate of reinforcement (Experiment 3). Moreover, bout-initiation responses were more susceptible to influence by rates of reinforcement than were within-bout responses across all experiments. In contrast, in the absence of a concurrent task, human schedule performance did not always display characteristics of nonhuman performance, but tended to be related to the relationship between rates of responding and reinforcement (feedback function), irrespective of the schedule of reinforcement employed. This was also true of within-bout responding, but not bout-initiations, which were not affected by the presence of a concurrent task. These data suggest the existence of two strategies for human responding on free-operant schedules, relatively mechanistic ones that apply to bout-initiation, and relatively explicit ones, that tend to apply to within-bout responding, and dominate human performance when other demands are not made on resources.