Search results for "Biomedical"
showing 10 items of 2328 documents
Biomechanical properties of oesophagus wall under loading
2003
In this investigation, firstly, the biomechanical properties of different parts of oesophagus were determined. Oesophagus stress and strain are the greatest in the cervical part for all age groups. The human oesophagus deforms unevenly, depending on the direction of load in relation to the organ's axis, it exhibits anisotropical behaviour. With the age the values of mechanical parameters of the oesophagus wall reduce, in particular beginning from 45 years of age, but the modulus of elasticity increases. Biomechanical properties of the oesophagus depend on the architecture of its structure. By loading the organ in the circumferential direction, microfibrilae rupture and deformation of the mu…
A custom image-based analysis tool for quantifying elastin and collagen micro-architecture in the wall of the human aorta from multi-photon microscopy
2014
The aorta possesses a micro-architecture that imparts and supports a high degree of compliance and mechanical strength. Alteration of the quantity and/or arrangement of the main load-bearing components of this micro-architecture - the elastin and collagen fibers - leads to mechanical, and hence functional, changes associated with aortic disease and aging. Therefore, in the future, the ability to rigorously characterize the wall fiber micro-architecture could provide insight into the complicated mechanisms of aortic wall remodeling in aging and disease. Elastin and collagen fibers can be observed using state-of-the-art multi-photon microscopy. Image-analysis algorithms have been effective at…
Repeatability assessment of biometric measurements with different refractive states and age using a swept-source biometer
2018
Background We aim to assess if refractive error or age may influence the repeatability of measurements using a swept-source biometer. Methods A total of 61 subjects were evaluated with IOLMaster 700 acquiring measurements of axial length (AL), central corneal thickness (CCT), white-to-white distance (WTW), anterior aqueous depth (AQD), lens thickness (LT), and keratometry (K) readings. Repeatability was evaluated classifying the sample according to the refractive state and age by the calculation of the within-subject standard deviation (Sw), coefficient of repeatability, and intraclass correlation coefficient. Results Very similar Sw was acquired among groups for AL, CCT, and WTW. Differenc…
Further development of a commercial driving simulation for research in occupational medicine
2012
Objectives: The purpose of this study was to refine a commercial car driving simulation for occupational research. As the effects of ethanol on driving behavior are well established, we choose alcohol as a test compound to investigate the performance of subjects during simulation. Materials and Methods: We programmed a night driving scenario consisting of monotonous highway and a rural road on a Foerst F10-P driving simulator. Twenty healthy men, 19-30 years, participated in a pilot study. Subjects were screened for simulator sickness, followed by training on the simulator one hour in total. Experiments were performed in the morning on a separate day. Participants were randomized into eithe…
COMPARISON OF T-1 ESTIMATION TECHNIQUES IN CARDIAC MRI
1994
International audience; Abstract: We have shown that the use of a simple combination of inversion recovery/spin-echo (IR/SE) sequences provides undeniably superior precision in quantitative in vivo myocardium T-1 estimation than the standard multiple spin-echo approach. On a group of 25 healthy subjects, the T-1 dispersion was, respectively, 3.8% for the IR/SE combination and 19.6% for the best SE pair combination. Moreover, repeated measurements were carried out on seven of the volunteers in order to assess T-1 reproducibility. The mean intra-individual T-1 precision was found to be 2.8% for the IR/SE pair and 20.0% for the best SE pair. The in vivo imaging work was supported and corrobora…
Ocular biometric repeatability using a new high-resolution swept-source optical coherence tomographer.
2020
To assess the repeatability of ocular biometric parameters using a high-resolution imaging device.74 healthy right eyes were included in this study. Five-repeated measurements were taken with ANTERION high-resolution swept-source optical coherence tomographer (SS-OCT) to measure: corneal thickness (central and at 2, 4 and 6-mm diameters), aqueous depth (AD), lens thickness (LT), anterior chamber volume (ACV), axial length (AL), and pupil (diameter and position). The intrasubject standard deviation (SWe have not found statistically significant differences between repeated measurements (p 0.05). The mean difference for corneal thickness was between -0.08 and 0.28 μm. For AD and LT was 0.004 …
Physician attitudes to blood pressure control
2011
OBJECTIVES: The Supporting Hypertension Awareness and Research Europe-wide (SHARE) physician survey aimed to qualify the key challenges that physicians face when trying to get patients to blood pressure (BP) goal. METHODS: The SHARE survey was open to physicians involved in the treatment of patients with hypertension, was anonymous, and was designed to take 15 min to complete. The survey included 45 questions covering physicians' demographic information, views on the BP targets recommended by the European Society of Hypertension-European Society of Cardiology guidelines, opinions on acceptable levels of BP control, and perceptions about the challenges associated with getting patients to BP …
Understanding the effect of window length and overlap for assessing sEMG in dynamic fatiguing contractions: A non-linear dimensionality reduction and…
2020
The Short-Time Fourier transform (STFT) is a helpful tool to identify muscle fatigue with clinical and sports applications. However, the choice of STFT parameters may affect the estimation of myoelectrical manifestations of fatigue. Here, we determine the effect of window length and overlap selections on the frequency slope and the coefficient of variation from EMG spectrum features in fatiguing contractions. We also determine whether STFT parameters affect the relationship between frequency slopes and task failure. Eighty-eight healthy adult men performed one-leg heel-rise until exhaustion. A factorial design with a window length of 50, 100, 250, 500, and 1000 ms with 0, 25, 50, 75, and 90…
Quantifying foot placement variability and dynamic stability of movement to assess control mechanisms during forward and lateral running
2015
Research has indicated that human walking is more unstable in the secondary, rather than primary plane of progression. However, the mechanisms of controlling dynamic stability in different planes of progression during running remain unknown. The aim of this study was to compare variability (standard deviation and coefficient of variation) and dynamic stability (sample entropy and local divergence exponent) in anterior–posterior and medio-lateral directions in forward and lateral running patterns. For this purpose, fifteen healthy, male participants ran in a forward and lateral direction on a treadmill at their preferred running speeds. Coordinate data of passive reflective markers attached …
Reproducibility of multiphase pseudo-continuous arterial spin labeling and the effect of post-processing analysis methods
2015
Arterial spin labeling (ASL) is an emerging MRI technique for non-invasive measurement of cerebral blood flow (CBF). Compared to invasive perfusion imaging modalities, ASL suffers from low sensitivity due to poor signal-to-noise ratio (SNR), susceptibility to motion artifacts and low spatial resolution, all of which limit its reliability. In this work, the effects of various state of the art image processing techniques for addressing these ASL limitations are investigated. A processing pipeline consisting of motion correction, ASL motion correction imprecision removal, temporal and spatial filtering, partial volume effect correction, and CBF quantification was developed and assessed. To fur…