Water-filled Trough Research Articles

Are 3 minutes good enough for obtaining baseline physiological samples from teleost fish?

A prerequisite to studying the physiological status of wild animals is the ability to obtain blood samples that reflect the condition prior to capture or handling. Based on research in avian taxa, it is recommended that such samples be obtained within 3 min of capture; however, this guideline has not been validated in wild teleosts. The present study addresses the time course of physiological changes in a number of blood metrics across six species of freshwater fish. Fishes were caught using a standardized angling protocol and held in a water-filled trough prior to the collection of a blood sample, via caudal phlebotomy, between 0.5 and 11 min after capture. Changes in whole-blood glucose and lactate concentrations, hematocrit, and plasma cortisol concentrations were assessed. Change-point analyses indicated that blood lactate concentrations and hematocrit did not deviate from baseline values until ∼2–5 min of handling for all species, whereas blood glucose concentrations generally did not deviate significantly from baseline over the 11 min test period. In all species, plasma cortisol concentrations began to increase above baseline between ∼4 and 8 min after capture. Thus, to ensure that blood samples are representative of baseline conditions across multiple metrics, we recommend that sampling be limited to less than 2 min in teleost fishes.

Numerical simulations of dipole sonic responses in a liquid-filled trough with arc-shaped section

To test the running performance of a sonic logging tool, it is an effective way to place the tool in a water-filled trough and record the sonic responses for an integrated check of the transducers in laboratory. Hence it is necessary to investigate the wave propagation in such a non-symmetric structure. In this study, we present the numerical modeling results of dipole sonic responses in a trough with arc-shaped section. A 3D cylindrical finite difference code as well as the irregular free-surface conditions is implemented. It is revealed that the flexural mode in a trough is evidently slower than that in a cylindrical pipe with same sizes. The flexural velocity decreases with the increasing gap angle of the trough. Moreover, the trough structure shows strong elastic anisotropy. The in-line responses (XX and YY) of the logging tool are difference in phases and amplitudes. The amplitudes of both cross-line responses (XY and YX), which reflect the level of anisotropy, become greater as the gap angle increas...

A New View of Pterosaur Feeding Habits

A New View of Pterosaur Feeding Habits

Plasma appearance of labeled β-carotene, lutein, and retinol in humans after consumption of isotopically labeled kale

The bioavailability of carotenoids from kale was investigated by labeling nutrients in kale with 13C, feeding the kale to seven adult volunteers, and analyzing serial plasma samples for labeled lutein, beta-carotene, and retinol. Ingested doses of labeled carotenoids were 34 micromol for beta-carotene and 33 micromol for lutein. Peak plasma concentrations, areas under the plasma concentration-time curves (AUCs), and percentages of dose recovered at peak plasma concentrations were calculated. Average peak plasma concentrations were 0.38, 0.068, and 0.079 microM for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. Average AUC values (over 28 days) were 42.8, 13.6, 13.2 microM h for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. Percentages of dose recovered at peak plasma concentrations were 3.6, 0.7, and 0.7% for [13C]lutein, [13C]beta-carotene, and [13C]retinol, respectively. A positive relationship was observed between baseline plasma retinol levels and [13C]retinol plasma response. It is possible that this relationship was mediated either through some aspect of beta-carotene absorption or via the common pathways of metabolism for postdose and endogenous retinoid.

Tests of emigration in small mammals under experimental conditions

Holding animals in enclosures that block emigration causes demographic abnormalities called "fence effects." Experimenters have built exits that require animals to move through unfavorable conditions to leave enclosures. There are doubts about whether individuals that cross these challenging exits are true emigrants. We tested whether an exit that required house mice (Mus musculus) to swim through a water-filled trough was used only by mice triggered to emigrate from an experimental enclosure. Also, we examined the responses of mice to the availability of resources and the presence of conspecific adult animals in a small enclosure with an exit and in an enclosure made by joining two single enclosures. All mice left a barren enclosure within 12 h but no mice left during 7-day trials in a resource-rich enclosure during spring and summer. At the end of trials with repeated introduction of pairs of mice, about 85% of resident mice were the first mice added. Nearly all mice added later left the enclosure. A relatively constant number of mice became residents in small enclosures and about 2.3 times as many mice resided in double enclosures. Mice readily found and used exits when motivated to leave and did not accidentally pass through exits during routine exploration. Thus, mice that stayed in enclosures were not "fenced in" by the water-filled exit and exhibited residency as in nature. Tests of exits should give ecologists confidence that animals can display normal residency and emigration behaviors in experimental settings. The defense of resources by residents and the emigration of excess animals resulted in a consistent limit to the number of animals able to reside in enclosures.

Observations of increased activity and tool use in captive rhesus monkeys exposed to troughs of water

This study investigated the effects of water troughs on nonhuman primates housed in a captive environment. Two groups of rhesus monkeys (Macaca mulatta) were exposed to water-filled troughs under three conditions: (1) standing water, (2) running water, and (3) a replication of standing and running water with novel objects. The effects of water exposure were assessed using a pretest phase (baseline), test phase (trough present), and posttest phase (baseline) design for each of the three conditions. Standing water produced different effects from running water. Monkeys were more active in the presence of standing water (higher levels of exploration and lower levels of social contact and grooming) than during baseline observations. In contrast, they were significantly more passive during the running water condition (higher levels of social contact) than baseline. Neither physical condition nor responses to dominance testing varied systematically over phases or between conditions. Tool use was observed during the standing water phases of Conditions 1 and 3. Three females from one group used a variety of cup-like containers as drinking utensils. A larger number of animals used the trough to soak chow prior to ingestion, and virtually all of the animals used the trough as a drinking source. These results suggest that exposure to water sources may elicit a broad spectrum of species-typical activity and may be a simple and inexpensive way to enrich the environment of captive rhesus monkeys. © 1993 Wiley-Liss, Inc.

Responses of electroreceptors in the snout of the echidna.

1. This is a report of experiments which provide evidence in support of the existence of an electric sense in the echidna, or spiny anteater Tachyglossus aculeatus. It is the first known example of electroreception in a terrestrial animal. 2. In each of four animals anaesthetized with alpha-chloralose, afferent responses were recorded in dissected filaments of the infraorbital branch of the trigeminal nerve which supplies skin of the upper jaw. Recordings were obtained from a total of forty-seven units identified as electroreceptors, by their responses to weak voltage pulses using focal stimulation of the moist skin surface. 3. In the absence of a stimulus, some receptors had an irregular resting discharge; others were silent. The receptive field for each receptor consisted of a discrete spot. Receptive fields were restricted to the tip of the snout. Cathodal stimulation over the receptive spot was excitatory for the duration of an applied voltage pulse. Reversal of stimulus polarity silenced any on-going activity and was followed by a post-anodal rebound excitation. 4. Receptor threshold was best measured not in air but with the snout immersed in tap water. An electric field was applied between a pair of large plate electrodes on either side of the snout. Threshold for thirty receptors lay in the range 1.8-73 mV cm-1. Measurements of response latency and of conduction path length gave estimates of axonal conduction velocities for the afferent fibres of 10-18 m Receptors responded to sinusoidally changing voltage gradients over the range 0.5-200 Hz with a maximum sensitivity at 20 Hz. 5. In one experiment a receptor site was marked with fine pins. Serial sections of the piece of underlying skin revealed a large mucus-secreting gland at the marked spot. Similar glands in skin of the platypus have previously been shown to be the sites of electroreceptors. 6. In a behavioural experiment an echidna was trained to choose between two identical tap water-filled troughs, one of which had a weak electric field across it. The animal learned to detect field strengths down to 1.8 mV cm-1 which corresponded to threshold for the most sensitive receptor measured in a subsequent electro-physiological experiment. It is concluded that the echidna, like the other Australian representative of the monotremes, the platypus, has an electric sense. It remains to be determined what kinds of sources of electric fields the animal encounters in its normal habitat.

Thermal assessment of surface troughs for 400 kV cables with air, backfill and water fillings

Abstract Using a full-scale water-filled trough an empirical formula for the heat transfer from the central cable has been obtained. This, together with assumed solar and wind quantities at the ground surface and the effective thermal resistance of the trough walls to ambient, yields the effective thermal resistance of the cable surface to ambient. The current rating obtained is compared with that with the trough having a filling of air and sand, and the rating is seen to be considerably higher.

Effects of Modification of the Plant Canopy Environment on Sclerotinia Blight of Peanut

Abstract The development of Sclerotinia blight, caused by Sclerotinia minor Jagger under various environmental conditions, was studied in field plots of peanuts (Arachis hypogaea L.). The peanut plant canopy was modified to produce desired environmental parameters. The modifications included the thinning of canopy foliage to allow air circulation that would decrease canopy humidity and the addition of water-filled troughs under an unthinned canopy that would increase humidity. Canopy relative humidity and soil moisture under the canopy was decreased by canopy thinning. Following infection by S. minor, the number of infection foci and disease development was reduced in the thinned canopy; however, thinning also reduced pod yield. Disease development was not increased, nor was yield affected by the addition of the water-filled troughs which increased humidity levels in the canopy. Soil moisture and canopy light interception were important variables in multiple linear regression models for the disease severity index and longest lesion length in the thinned and unthinned-trough plots.

Some Observations on the Mechanism of Entrainment

The turbulent entrainment process has been variously described as due to the effect of the small scale turbulence at the interface (Corrsin and Kistler, 1955; Townsend, 1966), the action of mixing jets which engulf volumes of fluid in bulk (Grant, 1958) and, most recently, a process of vortex pairing (Winant and Browand, 1974). A simple visualization study undertaken to examine the fundamental mechanism directly will be described in the present article. This experiment was conducted in the wake of a sphere towed through a water-filled trough, so that the “free stream” was actually motionless fluid. It was thus possible to mark a volume element of the free stream with dye, and follow its motion as it was injested by the wake. The common technique of injecting dye behind the model was used to make the wake itself visible. Motion pictures of the mixing process were made for subsequent study. Figure 1 is a tracing from this filmstrip.

Incremental stress under a two-dimensional artificial lake

Seismic activity has been induced by loading and possibly lubrication of faults in rocks underlying several artificial lakes. Such evidence of failure justifies study of incremental stress distributions produced by the filling of artificial lakes. In this paper two-dimensional lakes are considered. Equations are derived giving the incremental stress components due to a side of a water-filled trough of polygonal section in the surface of art elastic half-space. A computer program based on these equations is described. Distributions of stress parameters are shown for lakes of rectangular and isosceles triangular sections, and for a two-dimensional approximation of a section of the lake forming behind the Bennett Dam on the Peace River, British Columbia.

Research Items

PREHISTORIC COOKING-PLACES IN NORFOLK.—At the recent annual meeting of the Prehistoric Society of East Anglia, the president, Miss N. Layard, well known for her archseological investigations, particularly in the neighbourhood of Ipswich, delivered an address on prehistoric cooking-places in Norfolk. In the park at Buckenham Tofts, the discovery of what seems to have been a tribal cooking-place was due to rabbits scratching to the surface a number of cracked and fire-marked flints. The term usually applied to such articles is “pot-boilers,” but more probably the heated stones were dropped into water-filled troughs made of the skins of large animals, either suspended from poles or used to line pits in the ground. Water and meat are easily boiled in these circumstances by keeping up the supply of heated stones, and the result, as shown by experiments made by the lecturer, was a mixture of charcoal, dirt, and ashes, with well-boiled but discoloured meat.