Hybrid Collision Avoidance for ASVs Compliant With COLREGs Rules 8 and 13-17.

This paper presents a three-layered hybrid collision avoidance (COLAV) system for autonomous surface vehicles, compliant with rules 8 and 13-17 of the International Regulations for Preventing Collisions at Sea (COLREGs). The COLAV system consists of a high-level planner producing an energy-optimized trajectory, a model-predictive-control-based mid-level COLAV algorithm considering moving obstacles and the COLREGs, and the branching-course model predictive control algorithm for short-term COLAV handling emergency situations in accordance with the COLREGs. Previously developed algorithms by the authors are used for the high-level planner and short-term COLAV, while we in this paper further develop the mid-level algorithm to make it comply with COLREGs rules 13-17. This includes developing a state machine for classifying obstacle vessels using a combination of the geometrical situation, the distance and time to the closest point of approach (CPA) and a new CPA-like measure. The performance of the hybrid COLAV system is tested through numerical simulations for three scenarios representing a range of different challenges, including multi-obstacle situations with multiple simultaneously active COLREGs rules, and also obstacles ignoring the COLREGs. The COLAV system avoids collision in all the scenarios, and follows the energy-optimized trajectory when the obstacles do not interfere with it.

Reinforcement Learning-Based Tracking Control of USVs in Varying Operational Conditions.

We present a reinforcement learning-based (RL) control scheme for trajectory tracking of fully-actuated surface vessels. The proposed method learns online both a model-based feedforward controller, as well an optimizing feedback policy in order to follow a desired trajectory under the influence of environmental forces. The method's efficiency is evaluated via simulations and sea trials, with the unmanned surface vehicle (USV) ReVolt performing three different tracking tasks: The four corner DP test, straight-path tracking and curved-path tracking. The results demonstrate the method's ability to accomplish the control objectives and a good agreement between the performance achieved in the Revolt Digital Twin and the sea trials. Finally, we include an section with considerations about assurance for RL-based methods and where our approach stands in terms of the main challenges.

Primary Stenting of Right-Sided Subclavian Artery Stenosis Presenting as Subclavian Steal Syndrome: Report of 3 Cases and Literature Review.

BACKGROUND: Right-sided subclavian artery stenosis (SAS) is a rare cerebrovascular disease involving the upper extremities. Considering an endovascular approach for its management requires increased endovascular and catheterization skills when compared with the left side, due to the close approximation of the right subclavian artery origin, vertebral, and common carotid arteries. METHODS: Three patients suffering from proximal right-sided SAS were treated in our center through primary stenting. Percutaneous transfemoral and transbrachial approaches were used for vascular access, whereas in 2 cases an additional carotid protection device was deployed intraoperatively. RESULTS: Technical success was met in all 3 cases, with no intraoperative or postoperative complications being observed. All patients resumed ambulation and were uneventfully discharged the next day with dual antiplatelet medication. No recurrent stenosis was reported in duplex ultrasound scan during 6-month follow-up, with all patients reporting resolution of their symptoms. DISCUSSION: Subclavian artery stenosis is an uncommon vascular disease, showing a 4-fold left, rather than right-sided predisposition. Although a low-grade stenosis is usually asymptomatic and may remain unobserved, a severe stenosis may cause retrograde blood flow in the ipsilateral vertebral artery, leading to a medical condition with various clinical symptoms, known as subclavian steal syndrome. A number of open surgical techniques exist for management of subclavian artery stenosis, although a paradigm shift in the 21st century has led to the introduction of minimally invasive techniques for its treatment, with available modalities including angioplasty, stenting, and the kissing stent technique.

Recurrent haemoptysis, left-sided chest pain and an evolving left lower lobe cavity in a 50-year old smoker with prior high ethanol intake.

The authors describe a case of pancreatico-pleural fistula that presented as recurrent pyogenic chest disease in a patient with underlying ethanol related pancreatic disease. The diagnosis was suspected, given the context of non-resolving chest sepsis despite repeated antibiotics in a patient with known pancreatic disease. Although not revealed by initial tests the diagnosis was confirmed by repeating imaging investigations. The fistula was repaired surgically with consequent resolution of chest disease without need for extensive thoracic surgery.

Temocillin in the treatment of Burkholderia cepacia infection in cystic fibrosis.

BACKGROUND: Infections due to Burkholderia cepacia complex (Bcc) strains increase morbidity and mortality in cystic fibrosis (CF). Some transplant centres reject Bcc infected patients. We reviewed the results in patients treated with i.v temocillin. METHODS: Twenty-three patients who received 38 courses of temocillin (1988-1998) were identified from the CF database at Royal Brompton Hospital. In three patients' data were inadequate; therefore analysis was done in 20. Outcome was measured as improvement, deterioration or no change (compared to admission) in the following categories: clinical (temperature, dyspnoea, sputum volume, chest pain), physiological (FEV1, FVC, oxygen saturation) and inflammatory markers (WBC, ESR, CRP). Patients who improved in two categories were classified as having improved. Antibiotic sensitivities and outcome were recorded. RESULTS: In 18 of 32 courses (56.25%) improvement occurred. The organism (Bcc) in eight patients' sputum became resistant (three died). The antibiotics was changed in five patients with Bcc strains sensitive to temocillin because of no improvement and one patient due to allergy (rash). The average time to the next i.v antibiotic was 41 days. Eight patients died (in three the Bcc strain was resistant to temocillin). Fourteen patients with Bcc were transplanted and eight patients survived. Another patient who developed Bcc infection post-operatively, failing to respond to temocillin. CONCLUSIONS: These results suggest the potential benefit of i.v temocillin in CF patients with Bcc for exacerbations and at the time of transplantation.