On the discretisation of actuation in locomotion: Impulse- and shape-based modelling for hopping robots

In an age where computers challenge the smartest human beings in cognitive tasks, the conspicuous discrepancy between robot and animal locomotion appears paradoxical. While animals can move around autonomously in complex environments, today’s robots struggle to independently operate in such surroundings. There are many reasons for robots’ inferior performance, but arguably the most important one is our missing understanding of complexity. This thesis introduces the notion of discrete actuation for the study of locomotion in robots and animals. The actuation of a system with discrete actuation is restricted to be applied at a finite number of instants in time and is impulsive. We find that, despite their simplicity, such systems can predict various experimental observations and inspire novel technologies for robot design and control. We further find that, through the study of discrete actuation, causal relationships between actuation and resulting behaviour are revealed and become quantifiable, which relates the findings presented in this thesis to the broader concepts of complexity, self-organisation, and self-stability. We present four case studies in Chapters 3-6 which demonstrate how the concept of discrete actuation can be employed to understand the physics of locomotion and to facilitate novel robot technologies. We first introduce the impulsive eccentric wheel model which is a discretely actuated system for the study of hopping locomotion. We find that the model predicts robot hopping trajectories and animal related hopping characteristics by reducing the dynamics of hopping–usually described by hybrid differential equations–to analytic maps. The reduction of complexity of the model equations reveals the underlying physics of the locomotion process, and we identify the importance of robot shape and mass distribution for the locomotion performance. As a concrete application of the model, we compare the energetics of hopping and rolling locomotion in environments with obstacles and find when it is better to hop than to roll, based on the fundamental physical principles we discover in the model analysis. The theoretical insights of this modelling approach enable new actuation techniques and design for robots which we display in Robbit; a robot that uses strictly convex foot shapes and rotational impulses to induce hopping locomotion. We show that such systems outperform hopping with non-strictly convex shapes in terms of energy effective and robust locomotion. A system with discrete actuation motivates the exploitation of shape and the environment to improve locomotion dynamics, which reveals advantageous effect of inelastic impacts between the robot foot and the environment. We support this idea with experimental results from the robot CaneBot which can change its foot shape to induce timed impacts with the environment. Even though inelastic impacts are commonly considered detrimental for locomotion dynamics, we show that their appropriate control improves the locomotion speed considerably. The findings presented in this thesis show that discrete actuation for locomotion inspires novel ways to appreciate locomotion dynamics and facilitates unique control and design technologies for robots. Furthermore, discrete actuation emphasises the definition of causality in complex systems which we believe will bring robots closer to the locomotion behaviour of animals, enabling more agile and energy effective robots

Continuous infusion versus intermittent administration of meropenem in critically ill patients (MERCY): A multicenter randomized double-blind trial. Rationale and design

Meropenem is a β-lactam, carbapenem antibacterial agent with antimicrobial activity against gram-negative, gram-positive and anaerobic micro-organisms and is important in the empirical treatment of serious infections in Intensive Care Unit (ICU) patients. Multi-drug resistant gram-negative organisms, coupled with scarcity of new antibiotic classes, forced healthcare community to optimize the therapeutic potential of available antibiotics. Our aim is to investigate the effect of continuous infusion of meropenem against bolus administration, as indicated by a composite outcome of reducing death and emergence of extensive or pan drug-resistant pathogens in a population of ICU patients

High dose esomeprazole as an anti-inflammatory agent in sepsis: Protocol for a randomized controlled trial

Background: Sepsis is caused by dysregulated immune responses due to infection and still presents high mortality rate and limited efficacious therapies, apart from antibiotics. Recent evidence suggests that very high dose proton pump inhibitors might regulate major sepsis mediators' secretion by monocytes, which might attenuate excessive host reactions and improve clinical outcomes. This effect is obtained with doses which are approximately 50 times higher than prophylactic esomeprazole single daily administration and 17 times higher than the cumulative dose of a three day prophylaxis. We aim to perform a randomized trial to investigate if high dose esomeprazole reduces organ dysfunction in patients with sepsis or septic shock. Methods: This study, called PPI-SEPSIS, is a multicenter, randomized, double blind, placebo-controlled clinical trial on critically ill septic patients admitted to the emergency department or intensive care unit. A total of 300 patients will be randomized to receive high dose esomeprazole (80 mg bolus followed by 12 mg/h for 72 h and a second 80 mg bolus 12 h after the first one) or equivolume placebo (sodium chloride 0.9%), with 1:1 allocation. The primary endpoint of the study will be mean daily Sequential Organ Failure Assessment (SOFA) score over 10 days. Secondary outcomes will include antibiotic-free days, single organ failure severity, intensive care unit-free days at day 28, and mortality. Discussion: This trial aims to test the efficacy of high dose esomeprazole to reduce acute organ dysfunction in patients with septic shock. Trial registration: This trial was registered on ClinicalTrials.gov with the trial identification NCT03452865 in March 2018

Emotional status and fear in patients scheduled for elective surgery during COVID-19 pandemic: a nationwide cross-sectional survey (COVID-SURGERY)

Background Fragmented data exist on the emotional and psychological distress generated by hospital admission during the pandemic in specific populations of patients, and no data exists on patients scheduled for surgery. The aim of this multicentre nationwide prospective cross-sectional survey was to evaluate the impact of pandemic on emotional status and fear of SARS-CoV-2 contagion in a cohort of elective surgical patients in Italy, scheduled for surgery during the COVID-19 pandemic. Results Twenty-nine Italian centres were involved in the study, for a total of 2376 patients surveyed (mean age of 58 years ± 16.61; 49.6% males). The survey consisted of 28 total closed questions, including four study outcome questions. More than half of patients had at least one chronic disease (54%), among which cardiovascular diseases were the commonest (58%). The most frequent type of surgery was abdominal (20%), under general anaesthesia (64%). Almost half of the patients (46%) declared to be frightened of going to the hospital for routine checkups; 55% to be afraid of getting SARS-CoV-2 infection during hospitalization and 62% were feared of being hospitalised without seeing family members. Having an oncological disease and other patient-related, centre-related or perioperative factors were independently associated with an increased risk of fear of SARS-CoV-2 infection during hospitalization and of being hospitalised without seeing family members. A previous infection due to SARS-COV-2 was associated with a reduced risk of worse emotional outcomes and fear of SARS-CoV-2 infection during hospitalization. Patients who showed the most emotionally vulnerable profile (e.g. use of sleep-inducing drugs, higher fear of surgery or anaesthesia) were at higher risk of worse emotional status towards the hospitalization during COVID-19 pandemic. Being operated in hospitals with lower surgical volume and with COVID-19 wards was associated with worse emotional status and fear of contagion. Conclusions Additional fear and worse emotional status may be frequent in patients scheduled for elective surgery during COVID-19 pandemic. More than half of the participants to the survey were worried about not being able to receive family visits. Psychological support may be considered for patients at higher risk of psychological distress to improve perioperative wellbeing during the pandemic