Search results for "Biomedical engineering"
showing 10 items of 2020 documents
pH of multipurpose contact lens solutions over time
1998
The pH of nine different brands of multipurpose contact lens solutions available in Spain was determined over a period of 32 days after opening the bottles. Five bottles of nine solutions were used, each of which was buffered and obtained from different manufacturers. The pH measurements were taken using a micropH 2002 Crison pH-meter (accuracy +/- 0.001 pH units). Each solution was measured three times daily over the test period using 10-ml samples taken from the same container. Fluctuations in pH over time were observed but these were within the range of ocular comfort. The average pH of all the solutions tested proved to be between 6.99 and 7.56.
Clinical Experiences with Clamp Electrodes in Fetal Scalp for Simultaneous pO2 and ECG — Registration
1973
The development of a scalp electrode for continuous measurement of fetal mean tissue-PO2 and simultaneous registration of ECG respectively fetal heart rate has been described previously (1). The electrode mechanics and electronic equipment must be adapted to the various demands of the birth process and the labor room environment. The technical results are not yet refined, when unfavorable conditions prevail, artifacts may be anticipated. A brief review of the proceedings in electrode clamp measurements should be presented.
Eine Kombination niedrig und hochauflösender dynamischer T1-gewichteter Sequenzen zur besseren Beurteilung der Morphologie Kontrastmittel aufnehmende…
2002
Purpose: Presentation of a new protocol for simultaneous acquisition of both low and high resolution T 1 -weighted images of breast lesions for dynamic contrast-enhanced MR mammography. Demonstration of possible diagnostic improvement with representative measurements in patients with suspected breast cancer by adding morphologic parameters from high resolution sequences to the analysis of the signal-time curve. Materials and Methods: Dynamic MR imaging was performed with a 1.5 T system (Magnetom SONATA, Siemens Medical Systems, Germany) and the manufacturer's double-breast coil. Coronal T 1 -weighted 3D FLASH sequences (spatial resolution 1.25 ×1.25 mm 2 ; slice thickness 1.7 mm) were acqui…
Reliable Planar Object Pose Estimation in Light Fields From Best Subaperture Camera Pairs
2018
International audience; A light-field camera can obtain richer information about a scene than a usual camera. This property offers a lot of potential for robot vision. In this paper, we present a method for pose estimation of a planar object with a light-field camera. The light-field camera can be regarded as a set of sub-aperture cameras. Although any combination of them can theoretically be used for the pose estimation, the accuracy depends on the combination. We show that the estimated pose error can be reduced by selecting the best pair of sub-aperture cameras. We have evaluated the accuracy of our approach with real experiments using a light-field camera in front of planar targets held…
Hilbert-Huang versus Morlet wavelet transformation on mismatch negativity of children in uninterrupted sound paradigm
2008
Background Compared to the waveform or spectrum analysis of event-related potentials (ERPs), time-frequency representation (TFR) has the advantage of revealing the ERPs time and frequency domain information simultaneously. As the human brain could be modeled as a complicated nonlinear system, it is interesting from the view of psychological knowledge to study the performance of the nonlinear and linear time-frequency representation methods for ERP research. In this study Hilbert-Huang transformation (HHT) and Morlet wavelet transformation (MWT) were performed on mismatch negativity (MMN) of children. Participants were 102 children aged 8–16 years. MMN was elicited in a passive oddball parad…
Influence of Pendant Arms Bearing Ligating Groups on the Structure of Bismuth Porphyrins: Implications for Labeling Immunoglobulins Used in Medical A…
2004
International audience; The synthesis of two picket bismuth(III) porphyrins is reported, and their crystal structures are compared. The influence of the nature of the pickets, as well as their number, is discussed in terms of stability, kinetics of metalation, structure, and distortion of the porphyrin. Unexpectedly, the resultsindicate that the coordination sphere of bismuth is not affected by different types of distortion nor is the stability of the complex. For both types of complexes, the X-ray crystallography revealed that a single arm is actually in direct interaction with the bismuth cation, thereby allowing furtherfunctionalization on the porphyrin core as the linkage with immunoglo…
A granulometric analysis of specular microscopy images of human corneal endothelia
2005
The inner layer of the human cornea, called the corneal endothelium, plays an important role in the maintenance of corneal transparency. Specular microscopy is the most widely used technique to study the corneal endothelium in vivo. Improvements in technology have allowed us to obtain good quality specular images, but the detection and quantification of small size-shape cell changes is not obvious, specially when the physician wants to evaluate endothelial cell changes after some surgical procedures. This paper proposes a methodology to analyze specular microscopy images. Every corneal endothelium is described by means of different cumulative distribution functions or some moments (mean, st…
Digital holographic microscopy as a screening technology for diabetes
2019
Label-free quantitative phase imaging (QPI) is the hallmark of digital holographic microscopy (DHM). One of the most interesting medical applications of QPI-DHM is that it can be used to analyze illnesses in which the refractive index or/and the morphology of cells/tissues are distorted, from the acquisition of a single image. In this contribution, we obtain the phase maps of red blood cells (RBCs) samples of patients suffering from diabetes mellitus type 1 (DM1) by using a DHM. Our experimental results show that the measured phase values are significantly different between control non-diabetic and diabetic patients. The high correlation coefficient between the phase and the glycated hemogl…
Kognitive Prozesse und dynamische Zeitstrukturen. Vorstellung eines Meßgerätes zur Untersuchung der Mikro-Vigilanz-Shift-(MVS-)Hypothese. Cognitive P…
2003
The psychophysiological measuring method for the determination of the auditory order threshold (OT) is steadily gaining in importance, both for the diagnosis and treatment of speech disorders. Observed intraindividual variability of (macro-) vigilance led to the hypothesis of discontinuous cognitive processing in the central nervous system. The base for the variability of microvigilance is hypothesized to be in the phase difference of the alpha rhythm. To test for this hypothesis, we developed an EEG-comparator, which allows for a phase-dependent triggering of external stimuli. In direct comparison with stochastic (i.e. non-phase-dependent) stimulus presentation, the threshold in phase-depe…
Physiological Micromechanics of the Anterior Mitral Valve Leaflet
2011
An improved understanding of mitral valve (MV) function remains an important goal for determining mechanisms underlying valve disease and for developing novel therapies. Critical to heart valve tissue homeostasis is the valvular interstitial cells (VICs), which reside in the interstitium and maintain the extracellular matrix (ECM) through both protein synthesis and enzymatic degradation [1]. There is scant experimental data on the alterations of the MV fiber network reorganization as a function of load, which is critical for implementation of computational strategies that attempt to link this meso-micro scale phenomenon. The observed large scale deformations experienced by VICs could be imp…