Search results for "physiologic"
showing 10 items of 2593 documents
Different acute effects of single-axis and multi-axis hand-arm vibration.
1996
Under laboratory conditions the effects of single-axis and multi-axis hand-arm vibration exposure on several strain parameters were tested in up to 20 male subjects. As parameters of these acute effects, the biodynamic vibration behavior of the hand-arm system, the electrical activity of the most affected muscle groups, the skin temperature, the vibration sensitivity of the fingertips, and the subjective vibration sensation were measured. When comparing simulated three-axis vibration exposure with single-axis vibration exposure, synergistic effects in the form of an increasing reaction could be found. It could be proven that the vector sum of the frequency-weighted acceleration in the three…
Synchronization of Bioelectric Oscillations in Networks of Nonexcitable Cells: From Single-Cell to Multicellular States.
2019
Biological networks use collective oscillations for information processing tasks. In particular, oscillatory membrane potentials have been observed in nonexcitable cells and bacterial communities where specific ion channel proteins contribute to the bioelectric coordination of large populations. We aim at describing theoretically the oscillatory spatiotemporal patterns that emerge at the multicellular level from the single-cell bioelectric dynamics. To this end, we focus on two key questions: (i) What single-cell properties are relevant to multicellular behavior? (ii) What properties defined at the multicellular level can allow an external control of the bioelectric dynamics? In particular,…
Synchronized rotation in swarms of magnetotactic bacteria.
2017
Self-organizing behavior has been widely reported in both natural and artificial systems, typically distinguishing between temporal organization (synchronization) and spatial organization (swarming). Swarming has been experimentally observed in systems of magnetotactic bacteria under the action of external magnetic fields. Here we present a model of ensembles of magnetotactic bacteria in which hydrodynamic interactions lead to temporal synchronization in addition to the swarming. After a period of stabilization during which the bacteria form a quasiregular hexagonal lattice structure, the entire swarm begins to rotate in a direction opposite to the direction of the rotation of the magnetic …
Lärm als Umweltproblem
1976
Noise as an Environmental Problem. Anatomical structure and physiological function of the human ear are described. It is shown that constant noise stress leads to damage of certain parts of the inner ear. These damages proceed characteristically and may be diagnosed relatively early by means of audiometric tests. VDI-instructions 2058 (sheet 2) prescribes screening-tests for an earliest possible detection of incipient noise damage. In addition to ear-damaging effects of noise there have also been recorded physiological reactions under noise influence. Such disturbances, however, cannot as yet be described as an “Extraaural disease”. On the other hand, the fact that high sound intensities of…
Simulation of skin reflectance images using 3D tissue modeling and multispectral Monte Carlo light propagation.
2008
In this work we propose a method to simulate the expected, i.e. seen by a camera, multispectral reflectance images of a large skin surface area by combining Monte Carlo light propagation model and realistic tissue modeling based on three dimensional data acquisition of human body areas. In particular, we aim to simulate more accurately light transport in biological tissue by taking into account the geometrical topography of the skin surface, the structure and optical properties of the skin layers, and the subcutaneous veins in presence. We describe our computation method in detail and present simulated reflectance images results.
European vestibular experiments on the Spacelab-1 mission: 4. Thresholds of perception of whole-body linear oscillation.
1986
Thresholds for the detection of linear oscillatory motion at 0.3 Hz in the X, Y and Z body axes were determined during the flight of Spacelab-1 and on the ground pre- and post-flight, using the method of limits with a single staircase procedure. Pre-flight, Z axis thresholds (mean 0.077 ms-2) were significantly higher than X and Y thresholds (mean 0.029 ms-2). Measures obtained on three crew members in-flight exhibited thresholds greater, by a factor of 1.5-4.3, than those obtained pre-flight. Post-flight, two crew members had significantly elevated X and Y axis thresholds whereas the other two crew members had lowered thresholds in X, Y and Z axes. In general, thresholds had returned to pr…
Dzīvības procesu ķīmiskie regulatori: vitamīni un hormoni
1948
Tulkojums no krievu valodas.
Ligand-binding assays with OBPs and CSPs
2020
Assessing the ligand-binding properties of OBPs and CSPs is essential for understanding their physiological function. It also provides basic information when these proteins are used as biosensing elements for instrumental measurement of odors. Although different approaches have been applied in the past to evaluate the affinity of receptors and soluble binding proteins to their ligands, using a fluorescent reporter represents the method of choice for OBPs and CSPs. It offers the advantages of working at the equilibrium, being simple, fast and inexpensive, without requiring the use of radioactive tracers. However, as an indirect method, the fluorescence competitive binding approach presents d…
Treatment options in obstructive sleep apnea
2022
AbstractTreatment of OSA with CPAP is currently the recommended treatment and has the greatest evidence of efficacy on AHI, symptoms and comorbidities. Symptomatic patients with moderate-severe OSA generally have good adherence to CPAP therapy, while those with mild OSA, female, young and generally paucisymptomatic, have lower CPAP adherence, especially in the medium and long term. The recent identification of different clinical and pathophysiological phenotypes of OSA has paved the way for alternative treatments to CPAP, leading to an increasingly personalized therapy. Weight loss and lifestyle modifications are highly recommended in all obese or overweight patients. Mandibular advancement…
Equilibrium/steady-state concept in phytoplankton ecology
2003
This paper summarises the outcomes of the 13th Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP). The authors mostly addressed their contributions on the following topics: the effect of trophic state on the attainment of a steady-state; the establishment of equilibria in deep and shallow lakes; the role of spatial heterogeneity, disturbance, and stress in the establishment of equilibrium assemblages; the mechanisms leading to the steady state; the frequency and longevity of equilibrium phases, and the role of morphological and physiological plasticity of phytoplankton in maintaining the (apparently) same populations under different environmental condition…