Hybrid Volitional Control of a Robotic Transtibial Prosthesis using a Phase Variable Impedance Controller

For robotic transtibial prosthesis control, the global kinematics of the tibia can be used to monitor the progression of the gait cycle and command smooth and continuous actuation. In this work, these global tibia kinematics are used to define a phase variable impedance controller (PVIC), which is then implemented as the nonvolitional base controller within a hybrid volitional control framework (PVI-HVC). The gait progression estimation and biomechanic performance of one able-bodied individual walking on a robotic ankle prosthesis via a bypass adapter are compared for three control schemes: a passive benchmark controller, PVIC, and PVI-HVC. The different actuation of each controller had a direct effect on the global tibia kinematics, but the average deviation between the estimated and ground truth gait percentage were 1.6%, 1.8%, and 2.1%, respectively, for each controller. Both PVIC and PVI-HVC produced good agreement with able-bodied kinematic and kinetic references. As designed, PVI-HVC results were similar to those of PVIC when the user used low volitional intent, but yielded higher peak plantarflexion, peak torque, and peak power when the user commanded high volitional input in late stance. This additional torque and power also allowed the user to volitionally and continuously achieve activities beyond level walking, such as ascending ramps, avoiding obstacles, standing on tip-toes, and tapping the foot. In this way, PVI-HVC offers the kinetic and kinematic performance of the PVIC during level ground walking, along with the freedom to volitionally pursue alternative activities.Comment: 7 pages, 7 figures, submitted to ICRA 202

Nonequilibrium statistical mechanics and entropy production in a classical infinite system of rotators

We analyze the dynamics of a simple but nontrivial classical Hamiltonian system of infinitely many coupled rotators. We assume that this infinite system is driven out of thermal equilibrium either because energy is injected by an external force (Case I), or because heat flows between two thermostats at different temperatures (Case II). We discuss several possible definitions of the entropy production associated with a finite or infinite region, or with a partition of the system into a finite number of pieces. We show that these definitions satisfy the expected bounds in terms of thermostat temperatures and energy flow.Comment: 36 page

Consideraciones teórico-filosóficas que sustentan la investigación científica psicosocial y educacional

A partir de la revisión bibliográfica de literaturas especializadas sobre aspectos filosóficos (materialista-dialéctico-histórico y lógico-dialéctico y filosófico-marxista) así como de materiales especializados en metodología de la investigación científica y, haciendo énfasis en el procesamiento de toda la información, se utilizan los métodos de nivel teórico en la producción de conocimiento, tales como: Análisis-síntesis, histórico-lógico, inducción-deducción, modelación y enfoque sistémico-estructurar. Con la finalidad de exponer criterios de diferentes especialistas y de los autores criterios según experiencia y vivencia, algunas consideraciones teóricas que desde el punto de vista filosófico sustentan la investigación científica en los campos psicosocial y educacional

Multidetector Computed Tomography Evaluation of Uncommon Acute Post-Caesarean Section Complications

Introduction. The most common major abdominal surgery in women is caesarean section. Despite being a safe procedure, a variety of complications, both acute and chronic, can occur. About 14.5% of caesarean sections result in complications. Infection followed by postpartum haemorrhage is the most frequent complication. Imaging modalities such as ultrasonography and multidetector computed tomography are often used in the evaluation of suspected uncommon post-caesarean complications. Computed tomography has been found to be a good initial modality for assessing acute postoperative complications after caesarean delivery. The objective of the research was to evaluate the imaging findings and the characteristic visual manifestations of atypical acute complications of caesarean section, other than common complications such as postpartum haemorrhage, wound infection, etc. Materials and Methods. This prospective study was carried out at the Department of Radiodiagnosis and Imaging, Government Medical College, Srinagar from June 2019 to February 2020 in collaboration with the Department of General Surgery and Gynaecology and Obstetrics of the Sher-i-Kashmir Institute of Medical Sciences. All patients with suspected complication in the immediate post-caesarean period were evaluated with contrast-enhanced multidetector computed tomography. Results. Out of 427 patients who underwent caesarean section, 25 patients were suspected of having uncommon acute complications. Out of 25 patients evaluated for suspected immediate post-caesarean complication, only 5 patients had bladder flap hematoma, 8 patients were diagnosed with uterine dehiscence, 6 patients had uterine rupture, 3 patients suffered from ureteral injury, 1 patient had gossypiboma, 2 patients developed pelvic sepsis. Conclusions. Multidetector computed tomography plays an important role in detection and confirmation of multiple acute complications after caesarean delivery and can also help in guiding the management of complications as well

Finite-State Impedance and Direct Myoelectric Control for Robotic Ankle Prostheses: Comparing Their Performance and Exploring Their Combination

Non-volitional control, such as finite-state machine (FSM) impedance control, does not directly incorporate user intent signals, while volitional control, like direct myoelectric control (DMC), relies on these signals. This paper compares the performance, capabilities, and perception of FSM impedance control to DMC on a robotic prosthesis for subjects with and without transtibial amputation. It then explores, using the same metrics, the feasibility and performance of the combination of FSM impedance control and DMC across the full gait cycle, termed Hybrid Volitional Control (HVC). After calibration and acclimation with each controller, subjects walked for two minutes, explored the control capabilities, and completed a questionnaire. FSM impedance control produced larger average peak torque (1.15 Nm/kg) and power (2.05 W/kg) than DMC (0.88 Nm/kg and 0.94 W/kg). The discrete FSM, however, caused non-standard kinetic and kinematic trajectories, while DMC yielded trajectories qualitatively more similar to able-bodied biomechanics. While walking with HVC, all subjects successfully achieved ankle push-off and were able to modulate the magnitude of push-off via the volitional input. Unexpectedly, however, HVC behaved either more similarly to FSM impedance control or to DMC alone, rather than in combination. Both DMC and HVC, but not FSM impedance control, allowed subjects to achieve unique activities such as tip-toe standing, foot tapping, side-stepping, and backward walking. Able-bodied subject (N=6) preferences were split amongst the controllers, while all transtibial subjects (N=3) preferred DMC. Desired performance and ease of use showed the highest correlations with overall satisfaction (0.81 and 0.82, respectively)

Performance evaluation of strip parquet flooring panels after long-term, in-service exposure

Due to its extraordinary hardness, decorative appearance and possible small dimensions, black locust wood is assumed to be an excellent material for strip parquetflooring. The favourable colour changes achieved by controlled steam treatment further increased the utilization potential of this material. Flooring was installed on a student dormitory stair landing in heavy use. Due to the flooring’s very high exposure, 5 years was considered a long enough period to compare the different face layer materials during in-service test. Oil was used as a coating to avoid the remarkable protecting effect of hard film-forming varnishes (acrylic, etc.) against abrasion. Besides the flooring turning grey (all face layers no matter what treatment), only some delamination occurred at certain places after five years in service.The laboratory test results for abrasion resistance, dimensional changes and deformation were analysed. Additionally, the Brinell-Mörath hardness after indoor service and the abrasion due to indoor service were analysed. In terms of abrasion resistance, dimensional changes and deformation, no essential differences werefound between the oil-treated and untreated black locust wood on the one hand, and the control oak specimen on the other. Long-term tests showed that, after 5 years in service, the Brinell-Mörath-hardness decreased considerably for all the testedmaterials. The type of section and the presence of wide rays influenced the roughness and the waviness of the surface after indoor service

Předzávodní charakteristiky a závodní výkon hyponatremických a normonatremických závodníků českých ultra-závodů.

The aim of the study was to compare pre-race characteristics, race performance and plasma sodium [Na+] levels of hyponatremic and normonatremic ultra-endurance athletes and choosen variables in all finishers (n = 138). We assessed age, gender, club membership, pre-race training history and experience, pre-race body mass and body mass index (BMI) in 138 finishers of ultra-races (stage mountain bikers, 24-hr mountain bikers, 24-hr ultra-runners and 100-km ultra-runners) and post-race plasma [Na+] in a subgroup of 113 ultra-athletes.Cílem studie bylo porovnat předzávodní charakteristiky, závodní výkon a úrovneň sodíku v plazmě, a to u hyponatremických a normonatremických ultra-vytrvalostních sportovců

Survival and disease characteristics of de novo versus recurrent metastatic breast cancer in a cohort of young patients.

BACKGROUND: It is not clear how the pathology, presentation and outcome for patients who present with de novo metastatic breast cancer (dnMBC) compare with those who later develop distant metastases. DnMBC is uncommon in younger patients. We describe these differences within a cohort of young patients in the United Kingdom. METHODS: Women aged 40 years or younger with a first invasive breast cancer were recruited to the prospective POSH national cohort study. Baseline clinicopathological data were collected, with annual follow-up. Overall survival (OS) and post-distant relapse-free survival (PDRS) were assessed using Kaplan-Meier curves. RESULTS: In total, 862 patients were diagnosed with metastatic disease. DnMBC prevalence was 2.6% (76/2977). Of those with initially localised disease, 27.1% (786/2901) subsequently developed a distant recurrence. Median follow-up was 11.00 years (95% CI 10.79-11.59). Patients who developed metastatic disease within 12 months had worse OS than dnMBC patients (HR 2.64; 1.84-3.77). For PDRS, dnMBC was better than all groups, including those who relapsed after 5 years. Of dnMBC patients, 1.3% had a gBRCA1, and 11.8% a gBRCA2 mutation. CONCLUSIONS: Young women with dnMBC have better PDRS than those who develop relapsed metastatic breast cancer. A gBRCA2 mutation was overrepresented in dnMBC

A ADSORÇÃO DE PROTEINAS NO ESPAÇO DE OSTEOCONDUÇÃO

Introduction: Osseointegration is a process that allows the interaction of titanium implants with bone tissue. This interface is permeated by a protein anchoring so that the biomaterial is not in direct contact with the periosteum. Objective: This literature review aims to present the process of protein adsorption in osseointegrated implants, highlighting the main proteins that participate in this process. Methodology: The search was conducted on the PubMed, SciELO and Google Academic platforms with articles published between 2008 and 2022 in Portuguese and English. Results: Soon after implant installation, a provisional fibrin matrix is formed (angiogenesis process) that precedes osseointegration. Afterwards, in the osteoconduction space, there is an interaction between the titanium implant surface and proteins from the cell membrane. Thus, this protein interaction will support the peri-implant ligament. However, different factors such as implant surface properties and protein properties may influence this adsorption process. Conclusion: In this sense, it can be assumed that protein adsorption is an indispensable mechanism for successful osseointegration in titanium and titanium alloy implants.  Introdução: o processo de osseointegração é um processo que permite a interação dos implantes de titânio com o tecido ósseo. No qual essa interface é permeada por um ancoramento proteico de modo em que o biomaterial não fica em contato direto com o periósteo. Objetivo: essa revisão de literatura busca apresentar o processo de adsorção de proteínas em implantes osseointegráveis destacando as principais proteínas que participam desse processo. Metodologia: a pesquisa foi realizada nas plataformas PubMed, SciELO, e Google Acadêmico com artigos publicados entre o período de 2008 a 2022, nos idiomas português e inglês. Resultados: logo após a instalação do implante, ocorre a formação de uma matriz provisória de fibrina (processo de angiogênese) que precede a osseointegração. Em seguida, no espaço de osteocondução, ocorre a interação entre a superfície do implante de titânio com proteínas da membrana plasmática das células. Assim, essa interação proteica subsidiará o ligamento peri-implantar. Contudo, diferentes fatores como propriedades de superfície dos implantes e propriedades das proteínas podem influenciar nesse processo de adsorção. Conclusão: nesse sentido, pode-se presumir que a adsorção de proteínas é um mecanismo imprescindível para o sucesso da osseointegração em implantes de titânio e ligas de titânio