Effect of seawater velocity on inorganic nitrogen uptake by morphologically distinct forms of Macrocystis integrifolia from wave-sheltered and exposed sites

In conditions of low water motion (<0.06 ms^–1), the availability of essential nutrients to macroalgae, and thus their potential productivity, may be limited by thick diffusion boundary-layers at the thallus surface. The ability of macroalgae to take up nutrients in slow moving water may be related to how their blade morphology affects diffusion boundarylayer thickness. For the giant kelp, Macrocystis integrifolia Bory, morphological measurements indicate that blades of plants from a site exposed to wave action are thick, narrow and have a heavily corrugated surface. In contrast, blades from a site with a low degree of water motion are relatively thin, with few surface corrugations and large undulations along their edges. The aim of our work was to test the hypothesis that morphological features of M. integrifolia blades from a sheltered site allow enhanced inorganic nitrogen uptake at low seawater velocities compared to blades with a wave-exposed morphology. The rate of nitrate and ammonium uptake by morphologically distinct blades of M. integrifolia, from sites that were sheltered from and exposed to wave action, were measured in the laboratory at a range of seawater velocities (0.01 to 0.16 ms^–1), between March and May 1993. For both sheltered and exposed blade morphologies, nitrate and ammonium uptake rates increased with increasing seawater velocity, reaching a maximum rate at 0.04 to 0.06 ms^–1. Uptake parameters V _max (maximum uptake rate) and U _0.37 (the velocity at which the uptake rate is 37% of the maximum rate) were estimated using an exponential decay formula. These parameters were similar for both blade morphologies, at all seawater velocities tested. Additional measurements suggest that the nitrogen status of M. integrifolia blades from wavesheltered and exposed sites were similar throughout the experimental period, and thus nitrogen status did not affect the rate of nitrogen uptake in these experiments. on the basis of these results, we conclude that blade morphology does not enhance nitrogen uptake by M. integrifolia in conditions of low water motion. Potential effects of diffusion boundary-layers on kelp productivity are discussed.     

Prenatal diagnosis of mosaic tetrasomy 5p

We report the prenatal diagnosis of a fetus with tetrasomy 5p mosaicism resulting from a supernumerary isochromosome for the short arm of chromosome 5. The pregnancy was terminated and fetal autopsy revealed minor facial abnormalities (long philtrum, up-slanting palpebral fissures and a broad nasal bridge). Cultures were established from fetal skin, kidney, and pancreas for cytogenetic analysis; the i(5p) was observed only in the skin fibroblasts. To our knowledge, this is the fourth report of mosaic tetrasomy 5p and the first report of prenatal diagnosis of this abnormality. Copyright © 2001 John Wiley & Sons, Ltd.     

Progress in teenage crash risk during the last decade

OBJECTIVE: The purpose of the present study was to examine the most recent data on teenagers' fatal and nonfatal crashes in the United States to determine current crash rates as well as changes in crash rates during the past decade METHODS: Data for calendar years 1996 and 2005 were extracted for fatal crashes from the Fatality Analysis Reporting System and for police-reported crashes from the National Automotive Sampling System/General Estimates System. To calculate crash rates, population data were obtained from the Census Bureau, and mileage data were obtained from the 2001 National Household Travel Survey RESULTS: During 2001-02, the latest year for which mileage data are available, 16 year-old drivers had higher fatal and nonfatal crash rates per mile traveled than all but the very oldest drivers. However, fewer 16 year-olds typically are licensed to drive and they drive fewer miles per year than all but the oldest drivers. Thus, their fatal and nonfatal crash rates per population in 2005 were lower than among other teenagers and among drivers 20-29. During the past decade the most progress has been made in reducing crashes among the youngest drivers. Between 1996 and 2005 both fatal and police-reported crashes per population declined about 40% for 16 year-old drivers, compared with about 25% for 17 year-old drivers and 15-19% for 18 year-old drivers. The greatest reductions for 16 year-olds occurred in nighttime crashes, alcohol-related fatal crashes, and fatal crashes involving multiple teenage passengers. CONCLUSIONS: Substantial progress has been made in reducing fatal and nonfatal crashes per population among 16 year-old drivers. Although this study was not designed to examine the role of graduated licensing, the results are consistent with the increased presence of such laws, many of which restrict nighttime driving and driving with teenage passengers. IMPACT ON INDUSTRY: Restrictions on nighttime driving and driving with teenage passengers should be made a part of all states' graduated licensing systems. Historically, 16 year-olds have had the highest crash risk per licensed driver and per mile traveled. Given the dramatic reductions in per population crash rates among 16 year-olds, it is possible that their per mile and per licensed driver rates also have declined and may no longer be as elevated relative to other ages. However, shortcomings in the licensed driver data and a lack of recent mileage data hamper our ability to examine these issues. If we are to continue to provide a yardstick against which we can measure progress among the youngest drivers, immediate steps need to be taken to restore the availability of reliable exposure data.     

Social innovation and the governance of sustainable places

This article explores social innovation as a tool for the promotion of place-based sustainable development. The literature highlights the satisfaction of basic needs and situations of crises as two major drivers of socially innovative actions. We use these insights to explore the conditions under which social innovation can lead to social transformation and sustainable place making. We also recognise that social processes occur through, and are shaped by, the material forms that constitute and are constituted in place-specific settings. This highlights the deep interconnections that exist between place making and the resources, attributes and characterises – the materiality (such as rivers, soil, trees) – that exist within that locality. It is here that a close tie can be discerned between understanding the adaptive process in complex socio-ecological systems and the role of social innovation in such adaptation. Socially innovative initiatives at the community level can also be scaled upwards through the co-ordinating role of the state, while at the same time act as a pressure for more participatory forms of governance. Governance processes that enhance the role of both economic and social actors in the steering of social change help to infuse more open, democratic practices into social steering. With social, economic and state actors co-mingling as agents of social change, social innovation can come to play a key role in enhancing sustainable human–environment interactions.     

A Spatially Explicit Model for Mapping Headwater Streams

Headwater streams are the primary sources of water in a drainage network and serve as a critical hydrologic link between the surrounding landscape and larger, downstream surface waters. Many states, including North Carolina, regulate activity in and near headwater streams for the protection of water quality and aquatic resources. A fundamental tool for regulatory management is an accurate representation of streams on a map. Limited resources preclude field mapping every headwater stream and its origin across a large region. It is more practical to develop a model for headwater streams based on a sample of field data that can then be extrapolated to a larger area of interest. The North Carolina Division of Water Quality has developed a cost‐effective method for modeling and mapping the location, length, and flow classification (intermittent and perennial) of headwater streams. We used a multiple logistic regression approach that combined field data and terrain derivatives for watersheds located in the Triassic Basins ecoregion. Field data were collected using a standard methodology for identifying headwater streams and origins. Terrain derivatives were generated from digital elevation models interpolated from bare‐earth Light Detection and Range data. Model accuracies greater than 80% were achieved in classifying stream presence and absence, stream length and perennial stream length, but were not as consistent in predicting intermittent stream length.