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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Norwegian lobsterNephrops norvegicus (L.) collected from Firth of Clyde, Scotland between December 1987 and March 1988, was unable to survive longer than 18 h experimental emersion at 10°C. During this time the partial pressure of oxygen (P ν O2) in the venous blood decreased rapidly and the lobster supplemented cellular energy requirements by anaerobic metabolism. This was indicated by the rapid accumulation ofL-lactate in the blood. Although the survival rate increased (to ca 36 to 48 h) if lobsters were kept on ice, the accumulation ofL-lactate in the blood was not significantly different from lobsters at 10°C, despite the temperature difference. There was no indication thatN. norvegicus was able to further metabolize circulatingL-lactate during emersion. On emersion there was also a marked hyperglycemia in the blood due to the stress of handling and asphyxiation. There was fairly good agreement between results obtained during laboratory studies and simulated fishing activity in the Firth of Clyde. Both sets of results are discussed in the context of adaptation to air breathing within the Crustacea and an assesment of post-harvest treatment of lobsters.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 120 (1994), S. 231-237 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The oxygen-binding properties of haemocyanins (Hc) from three species of gammaridean amphipods, Gammarus locusta (L.) (subtidal), Echinogammarus pirloti (Sexton and Spooner), (intertidal, marine) and E. marinus (Leach) (intertidal, estuarine), one species of hyalid amphipod Hyale nilsonni Rathke (high intertidal, marine) and the talitrid amphipod Orchestia gammarellus (Pallas) (semi-terrestrial) have been studied. All the species were collected from the Firth of Clyde, Scotland, during the spring of 1992. The oxygen-carrying capacity of haemolymph from each species was low, although variable, and was correlated with the low concentration of Hc present. The Hc oxygen-affinity of native gammarid haemolymph was relatively high [partial pressure of oxygen required for half-saturation, P50=4 to 5 torr (0.53 to 0.67 kPa)] at their respective in vivo pH values. At equivalent pH, however, Hc from G. locusta displayed a lower O2-affinity than either Echinogammarus species. Gammarid Hcs had a large Bohr effect (Δ log P50/Δ pH=-1.16 to-1.47). Resuspended Hc isolated from whole H. nilsonni showed similar O2-binding properties to those of the gammaridean amphipods [P50=6.3 torr (1.44 kPa) at pH=8.0; Δlog P50/ΔpH=-1.20]. Comparable data for haemolymph from O. gammarellus showed that the Hc had a lower affinity for O2 [P50=14.1 torr (1.87 kPa) at in vivo pH] and exhibited a more moderate Bohr effect (Δ log P50/Δ pH=-0.79). To eliminate the possibility that these differences were due to the different haemolymph constituents, each of the Hcs were pelleted and resuspended in physiological saline. The differences noted above persisted, demonstrating that they were due to inherent O2-binding properties of the Hc molecules themselves. An increase in L-lactate resulted in an increase in Hc oxygen-affinity for both Echinogammarus species but not for O. gammarellus. This study has confirmed that there is a clear difference between Hcs from aquatic and semi-terrestrial amphipod genera. The results lend further support to the hypothesis that the move on to land by amphipod crustaceans is accompanied by a decrease in Hc oxygen-affinity, a decrease in the Bohr effect and a decrease in effector (in this case L-lactate) sensitivity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 124 (1995), S. 71-76 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The respiratory and acid-base responses to hypoxia of the sea urchin Psammechinus miliaris Gmelin have been studied both in the laboratory and in the field. Sea urchins were collected from the Clyde Sea area, Scotland, between March and July 1993. Individual urchins were unable to regulate their oxygen uptake during hypoxia. The partial pressure of oxygen (PO 2) in the coelomic fluid was lower than ambient PO 2 during normoxia but still decreased with a decrease in environmental PO 2. There was a significant increase in pH and in the concentrations of bicarbonate, magnesium and calcium in the coelomic fluid, but a significant decrease in the partial pressure of carbon dioxide (PCO 2), in response to declining PO 2s. The disturbance of respiratory parameters in urchins accompanying hypoxic exposure in rock pools was similar to that observed in the laboratory, although not as severe as might have been expected on the basis of the laboratory experiments.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural variation in the concentrations of haemocyanin ([Hc]) is examined for three decapod species collected from two different locations (Gullmarsfjord and Kattegat) off the west coast of Sweden (August to September 1998). Only one of the frequency distributions for [Hc] is normally distributed, and median values differ both between and within species. Differences in [Hc] cannot be attributed to sex, reproductive condition or moulting condition (over the limited range of moult stages examined) for any of the species. While body size did not scale with [Hc] for the Norway lobster Nephrops norvegicus or the swimming crab Liocarcinus depurator, it did for the spider crab Hyas araneus. To our knowledge this is the first time a negative relationship between body size and [Hc] has been reported for any crustacean. Thus the right-skewed frequency distribution of spider crab [Hc] could be accounted for by the right-skewed body size distribution recorded. The shape of the frequency distributions for [Hc] from the other two species could not be accounted for through differences in the factors examined here, although it is suggested that the amount of food consumed (or not) may be important.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using prawns, Palaemon elegans (Rathke) from intertidal pools on the Isle of Cumbrae, Scotland, and P. serratus (Pennant) from the subtidal at Plymouth, England, some metabolic responses to hypoxia and anoxia have been studied. P. elegans was found to have a greater tolerance of severe hypoxia than P. serratus. Tolerance of totally anoxic conditions, however, was limited to only 4 h in P. elegans and to approximately 1 h in P. serratus. exposure to moderate hypoxia (30 torr) resulted in little change in the concentration of L-lactate in the blood or in the tissues of either P. elegans or P. serratus. When exposed to extreme hypoxia (10 or 5 torr for P. elegans), however, there was a progressive increase in the concentration of L-lactate in the blood and in the tissues of both species. After normoxic conditions had been restored, the concentration of L-lactate in the blood and in the tissues returned to normal resting levels more rapidly in P. elegans than in P. serratus. Under hypoxic conditions, both P. elegans and P. serratus showed an increase in the concentration of blood glucose and a slight reduction in the glycogen content of the tissues. The concentrations of blood glucose and of tissue glycogen returned to normal levels within 6 h of the prawns being returned to normoxic conditions. The results of an in situ study in April and August 1986 to examine the metabolic responses of P. elegans to the hypoxic conditions normally experienced in high-shore rock pools are also presented. The ecological significance of the differing abilities of these species to survive hypoxic exposure is discussed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1084
    Keywords: Mammography ; Phosphor plates ; Modulation transfer function ; Image contrast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mammography and accurate microcalcification detection require very good spatial resolution. We have compared the diagnostic capabilities of reduced-exposure, third-generation, 5 cycles/mm computed radiography (CR) phosphor plates with conventional screen-film in 67 patients. No difference in diagnostic accuracy was detected. The digital characteristics of storage phosphor plates erabled us to study the relationship between contrast and spatial resolution. We developed a computer program to identify a single 100 μm pixel in a digital image and assign various gray levels to that pixel. Using this model, we determined that, for our 5 cycles/mm CR system, the imaged contrast of a 100 μm object was 62% of the original contrast. Current 5 cycles/mm phosphor plate systems cannot adequately detect microcalcifications that approximate 100 μm or smaller unless a magnification technique is used.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6087-6098 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Time-resolved infrared radiometry (TRIR) has been shown to be a valuable thermal characterization technique for the nondestructive evaluation of layered coatings. In this method an external step heating pulse is applied to the coating system and the resulting change in surface temperature is monitored as a function of time. Characteristic times and amplitudes can be ascribed to internal thermal reflections that return heat to the coating surface. A full description of the time dependence of the coating surface temperature can be obtained from these quantities. This paper describes a method for determining these characteristic times and amplitudes and shows their relationship to internal heat-flow patterns. Uses and limitations of the method are discussed, and comparison of the theory with experimental TRIR results is presented.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2895-2897 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thermoelastic transients observed in aluminum during the first few picoseconds after absorption of a subpicosecond duration laser pulse are described through numerical simulations using a nonlinear, two-temperature parabolic model of thermal stresses. Comparisons between these simulations and experimental measurements obtained from a single-crystal aluminum sample and polycrystalline aluminum films on silicon illustrate that the thermal and elastic transients must both be considered at all times in order for the physical properties that are interpreted from the experimental measurements to be consistent with those obtained from other measurements made at various time scales. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 645-647 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The distribution of electrons injected into CdS in a scanning electron microscope is imaged using an optical beam deflection technique. The contributions to the deflection due to carrier density, electron recombination, thermalization, and diffusion are identified for both pulsed and periodically modulated electron beams. The electron interaction volumes are analyzed to determine the energy dependence of the primary electron range and the lateral spread, presumably due to scattering of fast secondary electrons. The electron distributions are compared with Monte Carlo simulations.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2390-2392 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A passively mode-locked, flashlamp-pumped Nd:YAG laser with a cavity length of 11.19 m has been developed to study the noncontact generation of narrow-band ultrasound. The individual mode-locked pulses acted as separate sources of ultrasound, producing a train of acoustic pulses with a repetition rate of about 13.4 MHz. The ultrasound was generated in an aluminum sample and remotely detected with a path stabilized Michelson interferometer. The energy in the multiple pulse acoustic signal was confined to a considerably reduced spectral range compared with that in a single pulse.
    Type of Medium: Electronic Resource
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