Search results for "Sensor"
showing 10 items of 4594 documents
Über das Wesen der optomotorischen Reaktionen
1953
Flying and swimming animals need to be able to avoid passive displacement by air and water currents. Optomotor reactions essentially serve this purpose. The animals must be able to distinguish precisely between sensory stimulation caused by passive displacement and by active locomotion. Stimulation due to active movements does not release optomotor reactions. Apparent exceptions to this rule, occurring only under artificial circumstances, are caused by a derangement of either normal sensory stimulation or normal movement and, consequently, of their normal correlation. Examples of both cases are discussed.
Fine structure of sensilla during moulting inNeomysis integer (Leach) (Crustacea, Mysidacea)
1980
During the moulting cycle the sensory cells and the newly formed hair shaft remain connected to the old cuticular receptive apparatus of the sensillum by the elongated outer segments of the dendrites, which run through the exuvial space. A surface coat covering the outer dendritic segments protects them against the chemical influences of the exuvial fluid. The findings suggest that the receptors remain functional until ecdysis. This moulting type is considered to be a transitional form between the moulting types so far known.
Functional consequences of prejunctional receptor activation or blockade in the iris.
1994
The iris is innervated by nerves of the sympathetic, parasympathetic, and sensory nervous systems. The terminal nerve fibres are endowed with prejunctional receptors which modulate neurotransmitter release. Activation or blockade of prejunctional receptors by drugs may have an influence on iris smooth muscle tone. Several findings are in favour of the hypothesis that prejunctional receptors may be involved in regulation of iris smooth muscle tone and/or pathophysiological events. (i). Release of acetylcholine from parasympathetic nerves of guinea-pig iris sphincter evoked by electrical stimulation is subject to autoinhibition via prejunctional M2 muscarinic receptors, and the release can be…
New high piezoelectric coupling PLuNT binary system ceramics
1999
Abstract The new (1 − x)Pb( Lu 1 2 Nb 1 2 ) O 3 − x PbTiO 3 binary system ceramics in the interval 0 0.49). The morphotropic region extends over the interval x = 0.38–0.49, the concentration ratio M:T ≅ 1 corresponds to x = 0.41. The maximum values of the electromechanical coupling coefficients k p = 0.663, k t = 0.481, k 31 = 0.355 of (1 − x)PLuN-xPT ceramics were attained in compositions PLuNT 59/41 (T m = 353 °C) near the morphotropic phase boundary (MPB). The PLuNT system, having large values of electromechanical coupling and the highest T m (> 350 °C) among binary Pb(B′,B″)O 3 -PT perovskites may be favorable for piezoelectric sensors and actuators, and may have an interest as promisin…
Dielectric and Ultrasonic Investigation of Phase Transitions in PbFe1/2Nb1/2O3Ceramics
2012
We have investigated dielectric and acoustic properties of PbFe1/2Nb1/2O3 ceramics, obtained by conventional ceramic technology, in 120–450 K temperature interval. Dielectric response showed diffused dielectric permittivity maximum caused by ferroelectric phase transition around 380 K, but no dielectric anomalies associated with magnetic phase transition at low temperatures were observed. Formation of the polar phase was confirmed by ultrasonically detected piezoelectric sensitivity. Ultrasonic investigations using pulse-echo method showed two anomalous regions in temperature dependencies of ultrasonic velocity and attenuation, associated with magnetic and ferroelectric phase transitions.
Hydrogen sensor based on a palladium-coated fibre-taper with improved time-response
2006
Abstract We report an experimental study of the response of a hydrogen sensor, based on a palladium-coated tapered optical fibre, at different temperatures in the range −30 to 80 °C. We have studied the transmission, the time-response and the initial response velocity, being able to correlate these measurements with the pressure–composition isotherms of the Pd–H system and its phase transitions. Heating of the palladium layer optically with an auxiliary laser diode permits to improve the sensor's time-response at low temperatures.
A portable NMR sensor to measure dynamic changes in the amount of water in living stems or fruit and its potential to measure sap flow.
2014
Nuclear magnetic resonance (NMR) and NMR imaging (magnetic resonance imaging) offer the possibility to quantitatively and non-invasively measure the presence and movement of water. Unfortunately, traditional NMR hardware is expensive, poorly suited for plants, and because of its bulk and complexity, not suitable for use in the field. But does it need to be? We here explore how novel, small-scale portable NMR devices can be used as a flow sensor to directly measure xylem sap flow in a poplar tree (Populus nigra L.), or in a dendrometer-like fashion to measure dynamic changes in the absolute water content of fruit or stems. For the latter purpose we monitored the diurnal pattern of growth, ex…
The information content of odour, colour and tactile cues in the mate choice of minnows
2011
AbstractSexual displays often involve many different signal components, which may give information about the same or different mate qualities. We studied the information content of different signals in male minnows (Phoxinus phoxinus) and tested whether females are able to discriminate between males when only olfactory cues are present. We found that females preferred the odour of males with a more saturated (i.e., redder) belly, but only when the females had been in physical contact with the males before the experiments. Instead, when unfamiliar males were used, females did not discriminate between male odours and also the overall swimming activity (mate choice intensity) of the females wa…
Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells
2009
Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced …
Ultrasonic Guided Wave Inspection of Bonded Lap Joints: Noncontact Method and Photoelastic Visualization
2001
The main topic of this paper is the nondestructive inspection of adhesively bonded lap joints by using ultrasonic guided (plate) waves. A noncontact, couplant-free method that employs capacitive air-coupled transducers is demonstrated for the inspection of thin aluminum joints with dimensions typical of aircraft fuselage and wing panels. Two types of bond defects, disbonded regions and regions of poorly cured (low-cohesive-strength) adhesive, are successfully detected by measuring the amplitude decrease of selected plate waves leaking from one adherend to the other one through the bondline. It is shown that proper choice of the vibrating mode structure, in terms of cross-sectional displacem…