On a conjecture of Bergstra and Tucker

AbstractBergstra and Tucker (1983) conjectured that a semicomputable (abstract) data type has a finite hidden enrichment specification under its initial algebra semantics. In a previous paper (1987) we tried to solve the entire conjecture and we found a weak solution. Here, following the line and the proof techniques of the previous paper, we examine a nontrivial case in which the conjecture has a positive answer

Infectious agents including COVID-19 and the involvement of blood coagulation and fibrinolysis. A narrative review

Platelets, blood coagulation along with fibrinolysis are greatly involved in the pathophysiology of infectious diseases induced by bacteria, parasites and virus. This phenomenon is not surprising since both the innate immunity and the hemostatic systems are two ancestral mechanisms which closely cooperate favoring host's defense against foreign invaders. However, the excessive response of these systems may be dangerous for the host itself

Numerical simul tion of droplet impact erosion : dang van fatigue approach

The aim of this work is to understand the erosion mechanism caused by repeated water droplets impingement on a metallic structure, and then perform numerical simulations of the damage. When a high velocity water droplet with small diameter impacts a rigid surface, interaction is driven by inertial effects. Upon impact, the “water-hammer” pressure appears by inertial effect at the center of the contact though the maximum pressure occurs on the envelope of the contact area. Lateral jetting occurs by compression when the wave front travelling inside droplet overtakes the contact area. Concerning the structure, erosion is due to fatigue crack- ing. First, material grains are weakened during an “incubation” phase. After a large number of impacts, micro-cracks emerge and lead to ejection or fracture of grains, what is called “am- plification” phase. Numerical simulation including rigid solid allows to locate the most loaded zones of the area, by observing the pressure and mainly the impulse. A 2-way coupling compu- tation with fluid-structure interaction at macroscopic scale allows to confirm the fatigue-based mechanism by observing the hydrostatic stress. Finally, erosion program developed with Dang Van criterion provides the location of the most eroded zones of the structure during a loading cycle. They locate at the edge of jetting zone, which shows the influence of microjets in the erosion mechanism

The biology and treatment of acute long-bones diaphyseal fractures: Overview of the current options for bone healing enhancement

Diaphyseal fractures represent a complex biological entity that could often end into impaired bone-healing, with delayed union and non-union occurring up to 10% of cases. The role of the modern orthopaedic surgeon is to optimize the fracture healing environment, recognize and eliminate possible interfering factors, and choose the best suited surgical fixation technique. The impaired reparative process after surgical intervention can be modulated with different surgical techniques, such as dynamization or exchange nailing after failed intramedullary nailing. Moreover, the mechanical stability of a nail can be improved through augmentation plating, bone grafting or external fixation techniques with satisfactory results. According to the “diamond concept”, local therapies, such as osteoconductive scaffolds, bone growth factors, and osteogenic cells can be successfully applied in “polytherapy” for the enhancement of delayed union and non-union of long bones diaphyseal fractures. Moreover, systemic anti-osteoporosis anabolic drugs, such as teriparatide, have been proposed as off-label treatment for bone healing enhancement both in fresh complex shaft fractures and impaired unions, especially for fragility fractures. The article aims to review the biological and mechanical principles of failed reparative osteogenesis of diaphyseal fractures after surgical treatment. Moreover, the evidence about the modern non-surgical and pharmacological options for bone healing enhancement will discussed

Bringing the Embedded Systems Industry Towards Open Source: the SHARE project experience

International audienceOpen source software adoption in the embedded systems domain is gaining growing interest within the european industrial and academic communities due to the significant benefits it brings in terms of flexibility and cost reduction.Nonetheless, scepticism about open source as a viable option to support critical business functions still holds, since its decentralized and distributed development model makes quality evaluation and assessment hard to achieve. This paper reports the SHARE project experience, aimed at facilitating and promoting the use of open source software in the embedded systems industry. Performed activities, proposed methodology and achieved results are presented, along with lessons learned to exploit for enabling further initiatives in the next future

Analysis of Friction Stir Processed Surface Quality of AA2098 Aluminum Alloy for Aeronautical Applications

FSP is a relatively new technique that changes the microstructure on the surface of the material to improve mechanical properties in the desired zone. This study aimed to investigate the surface quality of AA2098 sheets after being subjected to friction stir processing under different conditions of feed rate and rotational speed. A DoE analysis was developed with two factors, feed rate and rotational speed, and three different levels of 75, 100, 125 mm/min and 1000, 1250, 1500 rpm respectively, in order to assess the processed surface quality. The Sa parameter was used to represent the surface quality in different zones of the process, near entrance tool, middle and near exit tool, and ANOVA analysis was conducted. The results indicated that only the position and feed rate have a statistical influence on surface roughness. Additionally, the surface quality is strongly affected by the position relative to the entrance of the tool and the side (retreating or advancing sides). The roughness was found to be significantly lower on the advancing side rather than on the retreating side

Complications and Intraoperative Fractures in Reverse Shoulder Arthroplasty: A Systematic Review

Introduction: The reverse shoulder arthroplasty is nowadays a treatment option for a variety of shoulder problems. As its incidence rose, also the number of complications increased, including intraoperative fractures. Significance: We performed a systematic review and critical analysis of the current literature following the PRISMA guidelines. Our purpose was to: 1) determine incidence, causes, and characteristics of intraoperative fractures; 2) evaluate their current treatment options, possible related complications, reoperation rates, and the patients’ outcome; and 3) determine the overall incidence of each complication related to reverse shoulder arthroplasty. The articles were selected from PubMed medical database in April 2020 using a comprehensive search strategy. Rayyan software was used to support the selection process of the records. A descriptive and critical analysis of the results was performed. Results: The study group included a total of 13,513 reverse shoulder arthroplasty procedures. The total number of complications was 1647 (rate 12.1%). The most common complication was dislocation (340 cases, rate 2.5%). Forty-six studies reported a total of 188 intraoperative fractures among the complications (rate 1.4%). The intraoperative fracture rate was 2.9% and 13.6% in primary and revision settings, respectively. There were 136 humeral fractures, 60% of them occurred in revision RSAs, during the removal of the previous implant, and involved the shaft in the majority of cases (39%). Glenoid fractures were 51 and occurred mostly during the reaming of the glenoid. We observed 7 further related complications (rate of 4%) and 3 reoperations (rate of 1.5%). The outcome was satisfactory in the majority of cases. Conclusions: A comprehensive review on intraoperative fractures in reverse shoulder arthroplasties is presented. Results suggest favorable outcomes for all treatment methods, with a modest further complication rate. This investigation may aid in the treatment decision-making for these complications

The Epidemiology of Fractures and Muskulo-Skeletal Traumas During COVID-19 Lockdown: A Detailed Survey of 17.591 Patients in a Wide Italian Metropolitan Area

Introduction: On 9 March 2020 the Italian Government declared a national lockdown to curb the spread of Covid-19. The aim of our study was to analyze the effects of such intervention on the traumatological emergency service, with particular emphasis on variations in trauma incidence and patients’ characteristics. Materials and Methods: An observational analysis was performed. Medical records were collected from 3 different trauma centers within a wide metropolitan area, and compared between 2 time periods: the full Italian lockdown period and the same period from the past year. The study population included all patients who were admitted to the Emergency Department (ED). For those who accessed for orthopedic reasons, the analyzed variables included the date of ED admission, age, gender, after visit discharge or hospitalization, place where the injury occurred, traumatic mechanism, diagnosis, relationship with sport activity, and time from injury/symptoms debut to ED access. Results: A total of 17591 ED accesses and 3163 ED trauma visits were identified. During the lockdown, ED trauma visits decreased by -59.8%, but required patient’s hospitalization significantly more frequently. The rate of ED trauma admissions in the elderlies significantly increased, together with the proportion of fragility fractures such as hip fractures. Road accident traumas (-79.6%) and sport-related injuries (-96.2%) significantly dropped. Admissions for less-severe reasons such as atraumatic musculoskeletal pain significantly decreased (-81.6%). Conclusions: The lockdown reduced the pressure on the Health System in at least 2 ways: directly, by curbing viral transmission and indirectly, by more than halving the ED trauma visits. Nonetheless, we observed an increased proportion of traumas in older patients, requiring hospitalizations, while the rate of less-severe cases decreased. This analysis may raise awareness of the effects of a lockdown on trauma services and may be helpful for those ones around the world who are now facing the emergency

Design and Evaluation of SmallFloat SIMD extensions to the RISC-V ISA

RISC-V is an open-source instruction set architecture (ISA) with a modular design consisting of a mandatory base part plus optional extensions. The RISC-V 32IMFC ISA configuration has been widely adopted for the design of new-generation, low-power processors. Motivated by the important energy savings that smaller-than-32-bit FP types have enabled in several application domains and related compute platforms, some recent studies have published encouraging early results for their adoption in RISC-V processors. In this paper we introduce a set of ISA extensions for RISC-V 32IMFC, supporting scalar and SIMD operations (fitting the 32-bit register size) for 8-bit and two 16-bit FP types. The proposed extensions are enabled by exposing the new FP types to the standard C/C++ type system and an implementation for the RISC-V GCC compiler is presented. As a further, novel contribution, we extensively characterize the performance and energy savings achievable with the proposed extensions. On average, experimental results show that their adoption provide benefits in terms of performance (1.64 7 speedup for 16-bit and 2.18 7 for 8-bit types) and energy consumption (30% saving for 16-bit and 50% for 8-bit types). We also illustrate an approach based on automatic precision tuning to make effective use of the new FP types