The Application of Feedback in Measurement

Instrument errors, error reduction, and elements of measurements for measurement systems with feedback instrumentatio

Capacitive pressure transducer system

Closed loop capacitive pressure transducer with extended frequency response for very low pressure measurement

Spatial and temporal variation in otolith chemistry for tautog (Tautoga onitis) in Narragansett Bay and Rhode Island coastal ponds

The elemental composition of otoliths may provide valuable information for establishing connectivity between fish nursery grounds and adult fish populations. Concentrations of Rb, Mg, Ca, Mn, Sr, Na, K, Sr, Pb, and Ba were determined by using solution-based inductively coupled plasma mass spectrometry in otoliths of young-of-the year tautog (Tautoga onitis) captured in nursery areas along the Rhode Island coast during two consecutive years. Stable oxygen (δ18O) and carbon (δ13C) isotopic ratios in young-of-the year otoliths were also analyzed with isotope ratio mass spectrometry. Chemical signatures differed significantly among the distinct nurseries within Narragansett Bay and the coastal ponds across years. Significant differences were also observed within nurseries from year to year. Classification accuracy to each of the five tautog nursery areas ranged from 85% to 92% across years. Because accurate classification of juvenile tautog nursery sites was achieved, otolith chemistry can potentially be used as a natural habitat tag

Application of the k-epsilon-v(exp 2) model to multi-component airfoils

Flow computations around two-element and three-element configurations are presented and compared to detailed experimental measurements. The k-epsilon-v(exp 2)(bar) model has been applied and the ability of the model to capture streamline curvature effects, wake-boundary layer confluence, and laminar/turbulent transition is discussed. The numerical results are compared to experimental datasets that include mean quantities (velocity and pressure coefficient) and turbulent quantities (Reynolds normal and shear stresses)

Zooplankton feeding behavior and particle selection in natural plankton assemblages containing toxic \u3cem\u3eAlexandrium\u3c/em\u3e spp.

Laboratory experiments suggest that toxic Alexandrium spp. cells are unpalatable to zooplankton grazers, and that toxic cells should be selectively avoided by zooplankton when feeding in mixtures of different prey species. Such avoidance, if practised in the wild, might contribute to harmful bloom formation by reducing losses of Alexandrium spp. due to grazing. In the spring of 1998 and 1999, during Œred tide¹ outbreaks in the southwestern Gulf of Maine, weekly experiments were performed using field collected natural water samples with ambient phytoplankton and dominant mesozooplankton grazers. The feeding response of Acartia hudsonica, Semibalanus balanoides nauplii, and Calanus finmarchicus was tested during various weeks in natural water samples with low concentrations of Alexandrium spp. (~1000 cells l-1, typical natural concentrations for this region). Semibalanus sp. nauplii consistently avoided toxic Alexandrium spp. and other dinoflagellates. C. finmarchicus selectively fed on diatoms when they were abundant, and fed non-selectively on all dinoflagellates (except Ceratium spp.) when the spring bloom declined and dinoflagellates dominated. A. hudsonica non-selectively cleared Alexandrium spp. throughout the study periods. During spring Alexandrium spp. bloom formation, if non-selective grazers such as A. hudsonica dominate the zooplankton, Alexandrium spp. losses from grazing depend on grazer abundance (biomass); if selective feeders such as S. balanoides nauplii dominate, then Alexandrium spp. benefits from reduced grazing losses relative to alternative prey

Effects of zooplankton size and concentration and light intensity on the feeding behavior of Atlantic mackerel \u3cem\u3eScomber scombrus\u3c/em\u3e

Atlantic mackerel Scomber scombrus had low clearance rates when fed older stage copepodites of the copepod Calanus finmarchicus at high concentrations and high clearance rates at low concentrations. These rates were consistent with filter feeding at high concentrations and particulate feeding at low concentrations. Intermediate and small copepods presented together at high concentrations were cleared at lower rates than the large C. finmarchicus, suggesting lower filtration efficiencies. Intermediate and small copepods were presented over a range of light intensities (8.2 x 10-8 to 1.6 x 100 µE m-2 s-1). Feeding rate did not change significantly between 1.6 x 100 and 2.0 x 10-6 µE m-2 s-1, but decreased to nearly zero at 8.2 x 10-8 µE m-2 s-1, indicating a light intensity threshold for feeding of about 10-7 µE m-2 s-1. This threshold enables mackerel to feed throughout the night near the ocean surface. Swimming speed decreased to a lesser degree than feeding rate at the lowest light intensity, indicating that the change in filter-feeding rate is only partially due to the change in speed. The school dispersed in both low and high light levels, but spacing between fish did not appear to be related to feeding rate

Nucleic acids and growth of \u3cem\u3eCalanus finmarchicus\u3c/em\u3e in the laboratory under different food and temperature conditions

We examined the effects of food concentration and temperature on nucleic acids and protein content of Calanus finmarchicus in order to evaluate the use of RNA as a growth rate index for this species. We measured RNA, DNA, and protein content of copepods reared from egg to adult stage in 5 combinations of food and temperature conditions (25 to 500 µg C l-1, 4 to 12°C). At 8°C, DNA, RNA and protein content and RNA:DNA differed among food treatments during Stages N6 through to adult female. Protein:DNA ratios and RNA:protein ratios were significantly different among food levels for only 3 of the 8 stages examined. At excess food, DNA, RNA, and protein content and RNA:DNA ratios were inversely related to temperature for most stages from C1 onward, but the effect of temperature was relatively small over the range of temperatures investigated. The RNA:DNA and protein:DNA ratios increased with developmental stage whereas the RNA:protein ratio and growth rates (measured in terms of protein, nitrogen, DNA, and carbon content) declined with increasing stage. Although the relationship of RNA:DNA to growth rates was stage-specific, the two were related when standardized for temperature and developmental stage. RNA:protein ratios were directly related to growth rates regardless of stage, and the slope of the relationship increased with increasing temperature in a nonlinear fashion. Our results emphasize the importance of temperature and developmental stage for the relationship of growth rates to RNA concentration and RNA:DNA ratios. We propose 2 ways to estimate in situ growth rates of C. finmarchicus from RNA:DNA or RNA:protein ratios and environmental temperatur