101 research outputs found

    The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking

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    Background: Robotic ankle-foot prostheses that provide net positive push-off work can reduce the metabolic rate of walking for individuals with amputation, but benefits might be sensitive to push-off timing. Simple walking models suggest that preemptive push-off reduces center-of-mass work, possibly reducing metabolic rate. Studies with bilateral exoskeletons have found that push-off beginning before leading leg contact minimizes metabolic rate, but timing was not varied independently from push-off work, and the effects of push-off timing on biomechanics were not measured. Most lower-limb amputations are unilateral, which could also affect optimal timing. The goal of this study was to vary the timing of positive prosthesis push-off work in isolation and measure the effects on energetics, mechanics and muscle activity. Methods: We tested 10 able-bodied participants walking on a treadmill at 1.25 m.s(-1). Participants wore a tethered ankle-foot prosthesis emulator on one leg using a rigid boot adapter. We programmed the prosthesis to apply torque bursts that began between 46% and 56% of stride in different conditions. We iteratively adjusted torque magnitude to maintain constant net positive push-off work. Results: When push-off began at or after leading leg contact, metabolic rate was about 10% lower than in a condition with Spring-like prosthesis behavior. When push-off began before leading leg contact, metabolic rate was not different from the Spring-like condition. Early push-off led to increased prosthesis-side vastus medialis and biceps femoris activity during push-off and increased variability in step length and prosthesis loading during push-off. Prosthesis push-off timing had no influence on intact-side leg center-of-mass collision work. Conclusions: Prosthesis push-off timing, isolated from push-off work, strongly affected metabolic rate, with optimal timing at or after intact-side heel contact. Increased thigh muscle activation and increased human variability appear to have caused the lack of reduction in metabolic rate when push-off was provided too early. Optimal timing with respect to opposite heel contact was not different from normal walking, but the trends in metabolic rate and center-of-mass mechanics were not consistent with simple model predictions. Optimal push-off timing should also be characterized for individuals with amputation, since meaningful benefits might be realized with improved timing

    Description of analyzing power and (p,n) reaction by a global dispersive coupled-channel optical model potential

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    A global dispersive coupled-channel optical model potential is used to analyze the proton elastic/inelastic analyzing power data and (p,n) data in order to investigate the prediction power of this potential. The numerical calculations show good agreement with available experimental data for proton elastic data and overall agreement for proton inelastic data. The results also showed that present global potential is approximately Lane-consistent, and can predict well the (p,n) cross sections

    Dispersive optical model description of nucleon scattering on Pb and Bi isotopes

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    A recently derived dispersive optical model potential (DOMP) for 208Pb is extended to consider the nonlocality in the real potential and the shell gap in the definition of the nuclear imaginary potentials near the Fermi energy. The modified DOMP improves the simultaneous description of nucleon scattering on 208Pb and of the 208Pb particle-hole bound states. This potential is shown to give a very good description of nucleon scattering data on near-magic targets 206,207Pb and 209Bi.Science Challenge Projects TZ2018001 y TZ201800

    Breast implant-associated anaplastic large cell lymphoma: a review

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    El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.Breast implant-associated anaplastic large cell lymphoma is a newly recognized provisional entity in the 2017 revision of the World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues. It is an uncommon, slow growing T-cell lymphoma with morphology and immunophenotype similar to anaplastic lymphoma kinase-negative anaplastic large cell lymphoma. However, the presentation and treatment are unique. Breast implant-associated anaplastic large cell lymphoma often presents as a unilateral effusion confined to the capsule of a textured-surface breast implant, a median time of 9 years after the initial implants have been placed. Although it follows an indolent clinical course, breast implant-associated anaplastic large cell lymphoma has the potential to form a mass, to invade locally through the capsule into breast parenchyma or soft tissue and/or to spread to regional lymph nodes. In most cases, an explantation with a complete capsulectomy removing all disease, without chemotherapy is considered to be curative and confers an excellent event free and overall survival. Here we provide a comprehensive review of breast implant-associated anaplastic large cell lymphoma, including history, epidemiology, clinical features, imaging and pathology findings, pathologic handling, pathogenic mechanisms, model for progression, therapy and outcomes as well as an analysis of causality between breast implants and anaplastic large cell lymphoma.Revisión por pare

    The natural-based antitumor compound T21 decreases survivin levels through potent STAT3 inhibition in lung cancer models

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    Lung cancer is the leading cause of cancer-related deaths worldwide; hence novel treatments for this malignancy are eagerly needed. Since natural-based compounds represent a rich source of novel chemical entities in drug discovery, we have focused our attention on tambjamines, natural compounds isolated from marine invertebrates that have shown diverse pharmacological activities. Based on these structures, we have recently identified the novel indole-based tambjamine analog 21 (T21) as a promising antitumor agent, which modulates the expression of apoptotic proteins such as survivin. This antiapoptotic protein plays an important role in carcinogenesis and chemoresistance. In this work, we have elucidated the molecular mechanism by which the anticancer compound T21 exerts survivin inhibition and have validated this protein as a therapeutic target in di erent lung cancer models. T21 was able to reduce survivin protein levels in vitro by repressing its gene expression through the blockade of Janus kinase/Signal Transducer and Activator of Transcription-3 (JAK/STAT3)/survivin signaling pathway. Interestingly, this occurred even when the pathway was overstimulated with its ligand interleukin 6 (IL-6), which is frequently overexpressed in lung cancer patients who show poor clinical outcomes. Altogether, these results show T21 as a potent anticancer compound that e ectively decreases survivin levels through STAT3 inhibition in lung cancer, appearing as a promising therapeutic drug for cancer treatment

    Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes

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    Bicarbonate is involved in a wide range of biological processes, which include respiration, regulation of intracellular pH and fertilization. In this study we use a combination of NMR spectroscopy and ion-selective electrode techniques to show that the natural product prodigiosin, a tripyrrolic molecule produced by microorganisms such as Streptomyces and Serratia, facilitates chloride/bicarbonate exchange (antiport) across liposomal membranes. Higher concentrations of simple synthetic molecules based on a 4,6-dihydroxyisophthalamide core are also shown to facilitate this antiport process. Although it is well known that proteins regulate Cl-/HCO3- exchange in cells, these results suggest that small molecules may also be able to regulate the concentration of these anions in biological systems

    Individualschutz durch Wirtschaftsgrundrechte im Gesellschaftsrecht

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    Los procesos de diseño, fabricación y explotación de la maquinaria agrícola están estrechamente relacionados con el aumento de los niveles de productividad, consumo de combustible y mejoramiento de las cosechas de caña. La presente investigación tiene como objetivo realizar un análisis comparativo de los indicadores técnicos explotativos en las cosechadoras de caña KTP-2M y KTP-3000S. En el análisis se demostró que el desempeño de la cosechadora KTP-3000S es superior a la KTP-2M, alcanzando valores significativos en cuanto a tiempo, eficiencia en el campo, coeficiente de seguridad técnica, materias extrañas durante el corte y valores de producción total, no teniendo este mismo comportamiento con los indicadores de consumo de combustible y valores de las pérdidas en cosecha de todo el período.Por lo que se puede afirmar que la cosechadora cañera KTP-3000S presentó un mejor desempeño durante el cumplimiento de su destino de servicio. // The processes of design, manufacture and operation of agricultural machinery are closely related to increased levels of productivity, fuel consumption and improving cane crops. This research aims to make a comparative analysis of the exploitative technical indicators cane harvesters KTP-2M and KTP-3000S. In the analysis it was demonstrated that the performance of the KTP-3000S harvester exceeds the KTP 2M, achieving significant values in terms of time, field efficiency, coefficient of technical safety, foreign matter field during cutting and values of total production not having this same behavior with fuel consumption indicators and values of crop losses throughout the period.So we can say that the KTP-3000S sugar cane harvester, presented a better performance during the fulfillment of its service destiny

    Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

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    Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

    Mitochondrial physiology

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    As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
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