Ratchet, pawl and spring Brownian motor

We present a model for a thermal Brownian motor based on Feynman's famous ratchet and pawl device. Its main feature is that the ratchet and the pawl are in different thermal baths and connected by an harmonic spring. We simulate its dynamics, explore its main features and also derive an approximate analytical solution for the mean velocity as a function of the external torque applied and the temperatures of the baths. Such theoretical predictions and the results from numerical simulations agree within the ranges of the approximations performed.Comment: Submitted to Physica

Energy-Efficient Assessment of Physical Activity Level Using Duty-Cycled Accelerometer Data

AbstractThis paper describes an energy efficiency improvement of the IMA accelerometer-based method for estimating the level of physical activity of a person. The sensor sampling and data processing requirements are significantly reduced by duty-cycling sensor sampling, thus making implementation and long-lasting operation possible on resource-constrained devices as sensor nodes. By duty-cycling, the system maintains adequate bandwidth, while still reducing the effective number of samples taken per unit of time. We analyze in detail the impact of duty-cycling on the accuracy of the method and show that we can reduce the duty-cycle to as little as 10%, incurring a mean error of only about 4%. This translates into energy saving of up to 60% on the sensor node

Extracellular vesicles from airway secretions: New insights in lung diseases

Lung diseases (LD) are one of the most common causes of death worldwide. Although it is known that chronic airway inflammation and excessive tissue repair are processes associated with LD such as asthma, chronic obstructive pulmonary disease (COPD) or idiopathic pulmonary fibro-sis (IPF), their specific pathways remain unclear. Extracellular vesicles (EVs) are heterogeneous na-noscale membrane vesicles with an important role in cell-to-cell communication. EVs are present in general biofluids as plasma or urine but also in secretions of the airway as bronchoalveolar lavage fluid (BALF), induced sputum (IS), nasal lavage (NL) or pharyngeal lavage. Alterations of airway EV cargo could be crucial for understanding LD. Airway EVs have shown a role in the pathogenesis of some LD such as eosinophil increase in asthma, the promotion of lung cancer in vitro models in COPD and as biomarkers to distinguishing IPF in patients with diffuse lung diseases. In addition, they also have a promising future as therapeutics for LD. In this review, we focus on the importance of airway secretions in LD, the pivotal role of EVs from those secretions on their pathophysiology and their potential for biomarker discovery

Circulating Exosomal Mir21 And Mir320 In Obstructive Sleep Apnea

Rational. Epidemiological studies indicate that there may be an association between obstructive sleep apnea (OSA) and cardiovascular and metabolic diseases. Some pro-inflammatory miRs (miR-21, miR320) critical for the immune response or hypoxia are often overexpressed in cancers and atherosclerosis. Aim. To examine the expression of miR-21& miR320 in circulating exosomes from patients with OSA. Methods: From a Sleep Unit and in the frame of a long-term longitudinal cohort study we selected 65 non-smokers OSA patients (apnea-hypopnea index -AHI- 30 events/ti) and 26 age, gender and BMI-matched controls (AHI 0.85 mm. Plasma-derived exosomes were isolated by precipitation using miRCURY, , , Exosome Isolation Kit. Exosomes were characterized by transmission electron microscopy, dynamic light scattering assay and Western Blot analysis using CD63 and HSP70. Exosome total RNA was obtained using miRCURY"* RNA isolation kit. miR-21 -5p and miR-320-3p were analysed by real time quantitative PCR (RT-qPCR) using miRCURY LNA~ technology..

Computational techniques for the assessment of fracture repair

The combination of high-resolution three-dimensional medical imaging, increased computing power, and modern computational methods provide unprecedented capabilities for assessing the repair and healing of fractured bone. Fracture healing is a natural process that restores the mechanical integrity of bone and is greatly influenced by the prevailing mechanical environment. Mechanobiological theories have been proposed to provide greater insight into the relationships between mechanics (stress and strain) and biology. Computational approaches for modelling these relationships have evolved from simple tools to analyze fracture healing at a single point in time to current models that capture complex biological events such as angiogenesis, stochasticity in cellular activities, and cell-phenotype specific activities. The predictive capacity of these models has been established using corroborating physical experiments. For clinical application, mechanobiological models accounting for patient-to-patient variability hold the potential to predict fracture healing and thereby help clinicians to customize treatment. Advanced imaging tools permit patient-specific geometries to be used in such models. Refining the models to study the strain fields within a fracture gap and adapting the models for case-specific simulation may provide more accurate examination of the relationship between strain and fracture healing in actual patients. Medical imaging systems have significantly advanced the capability for less invasive visualization of injured musculoskeletal tissues, but all too often the consideration of these rich datasets has stopped at the level of subjective observation. Computational image analysis methods have not yet been applied to study fracture healing, but two comparable challenges which have been addressed in this general area are the evaluation of fracture severity and of fracture-associated soft tissue injury. CT-based methodologies developed to assess and quantify these factors are described and results presented to show the potential of these analysis methods