37 research outputs found

    Energy Shaping Control of an Inverted Flexible Pendulum Fixed to a Cart

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    Control of compliant mechanical systems is increasingly being researched for several applications including flexible link robots and ultra-precision positioning systems. The control problem in these systems is challenging, especially with gravity coupling and large deformations, because of inherent underactuation and the combination of lumped and distributed parameters of a nonlinear system. In this paper we consider an ultra-flexible inverted pendulum on a cart and propose a new nonlinear energy shaping controller to keep the pendulum at the upward position with the cart stopped at a desired location. The design is based on a model, obtained via the constrained Lagrange formulation, which previously has been validated experimentally. The controller design consists of a partial feedback linearization step followed by a standard PID controller acting on two passive outputs. Boundedness of all signals and (local) asymptotic stability of the desired equilibrium is theoretically established. Simulations and experimental evidence assess the performance of the proposed controller.Comment: 11 pages, 7 figures, extended version of the NOLCOS 2016 pape

    Insight into the design and fabrication of a leaf-mimicking micropump

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    A micropump is the heart of any microfluidic device that finds applications in several lab-on-chip devices. Passive micropumps are highly desirable for this purpose due to their ease of integration, low energy requirements and simplistic design and operation. The design of a plant leaf serves as a natural inspiration for developing an evaporation assisted passive micropump. The presence of branching channel like venation pattern ensures water distribution to the spongy mesophyll cells increasing the surface area for evaporation. However, due to its multiscale design and complexity of the venation pattern, emulating a leaf's design is challenging. Apart from the lack of understanding of design parameters that affect fluid flow, manufacturing limitations impede the development of such bio-inspired micropumps. Inspired by the multi-scale design of the leaf, in this work we propose a passive micropump mimicking the structure of a leaf. Employing evaporation and capillary pressure as the pumping mechanism, our leaf mimicking micropump consists of a microporous membrane integrated with a branched, fractal channel network resembling a leaf's venation pattern. Our proposed fabrication methodology is simple, scalable, inexpensive and uses readily available materials. We demonstrate a significant increase in the fluid flow rate due to the addition of this branched channel network. We support our experimental observations using an analytical model, wherein we discuss the design parameters that affect the pumping rate. Correspondingly, the performance of these micropumps can be optimized based on intrinsic and extrinsic factors as per the desired applications

    A multidisciplinary consensus on the morphological and functional responses to immunotherapy treatment

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    The implementation of immunotherapy has radically changed the treatment of oncological patients. Currently, immunotherapy is indicated in the treatment of patients with head and neck tumors, melanoma, lung cancer, bladder tumors, colon cancer, cervical cancer, breast cancer, Merkel cell carcinoma, liver cancer, leukemia and lymphomas. However, its efficacy is restricted to a limited number of cases. The challenge is, therefore, to identify which subset of patients would benefit from immunotherapy. To this end, the establishment of immunotherapy response criteria and predictive and prognostic biomarkers is of paramount interest. In this report, a group of experts of the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Medical Radiology (SERAM), and Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM) provide an up-to-date review and a consensus guide on these issues

    Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021

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    BackgroundDisorders affecting the nervous system are diverse and include neurodevelopmental disorders, late-life neurodegeneration, and newly emergent conditions, such as cognitive impairment following COVID-19. Previous publications from the Global Burden of Disease, Injuries, and Risk Factor Study estimated the burden of 15 neurological conditions in 2015 and 2016, but these analyses did not include neurodevelopmental disorders, as defined by the International Classification of Diseases (ICD)-11, or a subset of cases of congenital, neonatal, and infectious conditions that cause neurological damage. Here, we estimate nervous system health loss caused by 37 unique conditions and their associated risk factors globally, regionally, and nationally from 1990 to 2021.MethodsWe estimated mortality, prevalence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs), with corresponding 95% uncertainty intervals (UIs), by age and sex in 204 countries and territories, from 1990 to 2021. We included morbidity and deaths due to neurological conditions, for which health loss is directly due to damage to the CNS or peripheral nervous system. We also isolated neurological health loss from conditions for which nervous system morbidity is a consequence, but not the primary feature, including a subset of congenital conditions (ie, chromosomal anomalies and congenital birth defects), neonatal conditions (ie, jaundice, preterm birth, and sepsis), infectious diseases (ie, COVID-19, cystic echinococcosis, malaria, syphilis, and Zika virus disease), and diabetic neuropathy. By conducting a sequela-level analysis of the health outcomes for these conditions, only cases where nervous system damage occurred were included, and YLDs were recalculated to isolate the non-fatal burden directly attributable to nervous system health loss. A comorbidity correction was used to calculate total prevalence of all conditions that affect the nervous system combined.FindingsGlobally, the 37 conditions affecting the nervous system were collectively ranked as the leading group cause of DALYs in 2021 (443 million, 95% UI 378–521), affecting 3·40 billion (3·20–3·62) individuals (43·1%, 40·5–45·9 of the global population); global DALY counts attributed to these conditions increased by 18·2% (8·7–26·7) between 1990 and 2021. Age-standardised rates of deaths per 100 000 people attributed to these conditions decreased from 1990 to 2021 by 33·6% (27·6–38·8), and age-standardised rates of DALYs attributed to these conditions decreased by 27·0% (21·5–32·4). Age-standardised prevalence was almost stable, with a change of 1·5% (0·7–2·4). The ten conditions with the highest age-standardised DALYs in 2021 were stroke, neonatal encephalopathy, migraine, Alzheimer's disease and other dementias, diabetic neuropathy, meningitis, epilepsy, neurological complications due to preterm birth, autism spectrum disorder, and nervous system cancer.InterpretationAs the leading cause of overall disease burden in the world, with increasing global DALY counts, effective prevention, treatment, and rehabilitation strategies for disorders affecting the nervous system are needed

    Continuous Focusing of Microparticles in Horizontally Actuated Rectangular Channels

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    We present a device to continuously focus microparticles in a liquid-filled open channel subjected to lateral vibration at frequencies of the order of 10 Hz. The vibration generates a capillary wave at the liquid-air interface. This capillary wave leads to a net motion of microparticles over multiple cycles, causing collection under the displacement nodes of the capillary wave. These accumulated particles are observed as a concentrated stream in the presence of a continuous flow along the open channel, which means that the channel can be designed such that the focused particle stream exits through one outlet, while the filtrate is removed via interspaced outlets on each side of the particle stream. A numerical model is proposed, which superimposes the periodic flow field due to the capillary wave and the inlet-induced transverse flow field between the inlet and the outlet. The model is utilized to predict the smallest distance from the inlet at which the focused stream of particles is obtained, termed here the collection length. In addition, experiments are performed for different channel and inlet sizes, vibration actuation amplitudes, flow rates, and particle sizes. By considering the design factors extracted from the modeling data, we demonstrate that the resulting device is capable of continuous particle collection down to 1 μm diameter, at flow rates of up to 1.2 ml/min
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