Effects of alcohol at 0.05% blood alcohol concentration (BAC) on low speed urban driving

ABSTRACT

Objective: Alcohol-impaired driving presents a continued risk for traffic safety and results in a significant proportion of fatalities on the roadway. We examined how alcohol at a 0.05% blood alcohol concentration (BAC) compares to 0.10% BAC (above the current U.S. legal limit) in terms of impact on driving performance.

Methods: Utilizing a within-subjects design, we recruited 108 healthy experienced drivers who were moderate to heavy drinkers. In a double-blind, placebo-controlled crossover design, we administered placebo and alcohol at the 0.05% and 0.10% BAC levels in a standardized simulated driving protocol. Drives occurred on the descending limb of the blood alcohol curve. This analysis focuses on the urban portion of the drive

Results: The study observed clear differences in performance for lateral and longitudinal driving performance and glance behavior. Variability in lane keeping and average speed increased with BAC level, with degraded performance observed at 0.05% BAC. The frequency of lane departures and percentage of time focused on the forward roadway at 0.05% BAC did not differ from placebo but differed from the 0.10% BAC level.

Conclusions: Overall, our results show that there is degraded performance in the urban driving environment and that much of that begins at or below the 0.05% BAC level.     

Is there a “sound window” for primate communication?

Summary It has long been asserted that habitat acoustics can determine the frequency band bestadapted for long-range communication, but the generality and validity of measurements claiming to demonstrate a window of best frequencies have recently been questioned. We report the discovery of a prominent sound window in Kenyan rain forest in a study that is free of methodological difficulties. Our results allow us to calculate the range advantage attained by an animal vocalizing within the sound window, and show that sound windows can be a potent factor for the evolution of primate communication.     

Heterotrophic bacteria in Long Island Sound

Correlated with a study of heterotrophic bacteria from cultures of larval bivalve molluses, bacteria were studied from the water column over an oyster bed in Lont Island Sound, USA. Samples taken biweekly for 1 year showed bacterial densities ranging from 1.2x10³/ml in summer to 3.8x10⁴/ml in winter. Variation in seasonal density mirrored that of phytoplankton. Gram-negativ rods constituted 99% of the isolate. Eight genera were identified, but 92.3% of these were Achromobacter, Flavobacterium, and Pseudomonas. Pseudomonads dominated the summer flora, whereas flavobacteria were most abundant in spring. Types varied seasonally, but proteolytic, lipolytic, and amylolytic activity appeared independent of season.     

Localized defecation by pike: a response to labelling by cyprinid alarm pheromone?

Fathead minnows (Pimephales promelas) that have never encountered a predatory pike (Esox lucius), are able to detect conspecific alarm pheromone in a pike's diet if the pike has recently consumed minnows. It remains unclear how this minnow alarm pheromone is secreted by pike and if a pike is able to avoid being labelled as a potential predator by localizing these cues away from its foraging range. The first experiment determined that minnow alarm pheromone is present in pike feces when pike are fed minnows. Individual fathead minnows exhibited a fright response to a stimulus of pike feces if the pike had been fed minnows, but not if the pike had been fed swordtails, which lack alarm pheromone. Individual minnows also exhibited a fright reaction to alarm pheromone in the water (which contained no feces) housing pike which had been fed minnows, suggesting that alarm pheromone is also released in urine, mucous secretions and/or via respiration. The second experiment determined that test pike spent a significantly greater proportion of time in the home area of the test tanks (i.e. where they were fed) but the majority of feces were deposited in the opposite end of the test tank. By localizing their defecation away from the home or foraging area, pike may be able to counter the effects of being labelled as a predator by the alarm pheromone of the prey species.     

Seasonal growth of the giant kelp Macrocystis pyrifera in New Zealand

The seasonal growth pattern of Macrocystis pyrifera (L.) C. Agardh in New Zealand was determined from measurements of blade-elongation rates between March 1986 and December 1987. Growth rates remained relatively constant throughout most of the year, but declined significantly during the summer months. Seawater nitrate levels had a marked seasonal cycle, with concentrations of 0.3 μM detected in summer. The timing of the decline in internal nitrogen concentrations varied for different-aged blades, but occurred ∼1 mo after the decrease in seawater nitrate concentrations. Sufficiently high irradiance levels and seawater nutrient concentrations support active growth for most of the year, but growth is nutrient-limited during summer. No carbon accumulation during summer was observed. Between March and August 1988, growth estimates were also derived from node-initiation rates and stipe-elongation rates to permit comparisons with previous studies from the northern and southern hemispheres. Direct comparisons of the three growth parameters determined for non-terminated canopy and sub-surface fronds were used to assess possible differential resource allocation in the two frond classes. Received: 16 May 1997 / Accepted: 28 May 1997     

The cause of size-assortative mating in the leaf beetle Trirhabda canadensis (Coleoptera : Chrysomelidae)

Summary Examples of positive assortative mating by body size are abundant but its causes remain controversial. I show that size-assortative mating occurs in the chrysomelid beetle Trirhabda canadensis and I test a series of alternative hypotheses to explain how this mating pattern comes about. Results suggest that assortative mating in this beetle is due to the greater ease with which size-matched pairs can achieve intromission, and not due to size-biased skews in the availability of mates or mate choice favoring large individuals. There was no correlation between male and female elytron length (a measure of body size) at the initiation of courtship, but pairs assorted positively by size at the onset of intromission. Moreover, in the laboratory, there was a negative correlation between male and female size for pairs engaged in courtship that terminated without mating. Assortative mating was not associated with a large-male mating advantage and there was no evidence of female choice of large males. Nor was there unequivocal evidence for male choice of large females; although mating females were slightly larger and considerably heavier than solitary females, males did not differ in the frequency with which they rejected large and small females. Assortative mating in T. canadensis appeared to be caused by the lower ability of mismatched pairs to achieve intromission after an encounter, both when males were larger and when they were smaller than the female.     

The effect of salinity on survival,bioenergetics and predation risk in the mud crabs <Emphasis Type="Italic">Panopeus simpsoni</Emphasis> and <Emphasis Type="Italic">Eurypanopeus depressus</Emphasis>

The effect of salinity on survival, bioenergetics and predation risk was studied in two common mud crabs in the Gulf of Mexico, Eurypanopeus depressus and Panopeus simpsoni. Eurypanopeus survived better at low salinities (the 28-day LC₅₀ of E. depressus was 0.19 PSU compared with 6.97 PSU for P. simpsoni). While low salinity increased energy expenditure and reduced food consumption and absorption, resulting in lower scope for growth, identical responses to salinity occurred in both species. Both species also had similar salinity-dependent patterns of hyper-osmoregulation. Because these physiological mechanisms could not explain differences between the two species in salinity tolerance, we explored the effect of salinity on competition for refugia. Eurypanopeus had higher resource holding potential for refugia, especially at low salinity. As a consequence it had lower predation risk to blue crabs in laboratory experiments. The higher tolerance by E. depressus for low salinities, and greater resource holding potential for refugia may explain why it has a more euryhaline distribution than P. simpsoni.     

Asynchronous deposition of dense skeletal bands in Porites lutea

Alternate dense and less-dense skeletal bands in massive corals have been used for many years to record the history of growth in species such as Porites lutea and Montastrea annularis, based on the assumption that one dense band and one less-dense band is equivalent to a year's growth. This report demonstrates that specimens of Porites lutea Edwards and Haime (collected from the same neighbourhood in Phuket, Thailand, from November 1983 through November 1984) produce skeletal bands asynchronously and that one year's growth in corals from certain sites may regularly consist of four bands of varying density. The annual banding pattern observed at all sites includes the deposition of a dense band in response to high sedimentation loads and, probably, reduced light levels.     

Stereophotography for the field biologist: measurement of lengths and three-dimensional positions of free-swimming sharks

A stereophotographic technique for determining size and relative position of free-swimming sharks is described and illustrated for schooling scalloped hammerhead sharks (Sphyrna lewini). The method yields total length and nearest-neighbor, interindividual distance; and each of these dimensions is expressed as a function of the shark's distance into a school on the vertical and horizontal planes. Stereopairs of photographs were taken by an aligned, beam-mounted pair of cameras (Nikonos III). The scale to determine the length of a shark from the paired photographic images was obtained from the horizontal displacement between the images. Displacement was correlated with optical axis separation from photographs of a scaled staff at known distances from the camera. Image dimensions on the photographs were measured by projecting a scale onto the stage through a camera lucida. The precision of repeated measurements of a 50 cm section of a scaled staff at increasing distances from the cameras of 2, 4, and 8 m was ±5.0%. Lengths of the sharks ranged from 109 to 371 cm, with a median of 178 cm, for 3 offshore sites in the Gulf of California during July and August 1979. At one site, El Bajo Gorda, lengths increased with both distance from the camera and distance into the group; in contrast, the interindividual distances (head-to-head) did not vary with distance into the group and possessed a median of 232 cm.