Arsenic-induced skin conditions identified in southwest dermatology practices: an epidemiologic tool?

Populations living in the Southwest United States are more likely to be exposed to elevated drinking water arsenic levels compared to other areas of the country. Skin changes, including hyperpigmentation and generalized hyperkeratosis, are the most common signs of chronic arsenic ingestion from drinking water. The purpose of this study was to determine the feasibility of using dermatology practices in New Mexico, Arizona, and western Texas as a surveillance system for arsenical skin disorders related to drinking water. Postcard questionnaires were mailed to practicing dermatologists. The number of cases of arsenical hyperpigmentation/keratoses seen by these dermatologists during the past 10 years and the past year were estimated. Of 240 dermatologists who were mailed questionnaires, 37 reported seeing 237 patients with arsenical hyperpigmentation/keratoses in the past 10 years and 35 patients in the past year. Since approximately one-eighth of dermatologists practicing in the Southwest saw at least one patient with arsenical hyperpigmentation/keratoses during one year, it appears feasible to complete a population-based study of these conditions.     

Sustainable development in the Baltic sea region. Governance beyond the nation state

After the end of the Cold War, the Baltic Sea Region (BSR) developed into a highly dynamic area of cross-border cooperation and transnational networking. Three forms of governance beyond the nation state and appropriate case studies are presented here: (1) the Helsinki Convention as an international regime; (2) Baltic 21, the world's first regional Agenda 21, as an international policy network; (3) the Union of the Baltic Cities (UBC) as a transnational network. The achievement of sustainable development in the BSR undoubtedly requires a fruitful combination of national governance and these forms of international and transnational governance. In this respect, international policy networks, such as Baltic 21, and transnational networks, such as the UBC, promise to provide new approaches that can complement international and intergovernmental cooperation between nation states. Furthermore, it must also be taken into account that governance in the BSR will soon become embedded in European governance and lead to the Europeanisation of the Baltic Sea Area.     

Untersuchungen zum ökotoxikologischen Schädigungspotenzial und Erosionsrisiko von kontaminierten Sedimenten in staugeregelten Flüssen

Particle-bound pollutants accumulate in river-bottom sediments, a process which results in a significant decrease in the ecotoxicological availability of toxicants for the majority of aquatic organisms. Under normal hydrologic conditions, the release of contaminants from bottom sediments is usually of minor importance. In contrast, flood events may remobilize highly contaminated sediments via in-stream erosion. The objective of this study was to develop a combined ecotoxicological and hydraulic approach to elucidate the ecotoxicological implications associated with the risk of erosion of contaminated sediments. This integrated strategy was applied to the lock-regulated Neckar river in Southern Germany. Both the bottom-sediment cores and suspended matter from two intensive flood events were investigated. Sediment samples below an erosional unconformity showed a sharp increase in the ecotoxicological load. Moreover, it was found that major flood events (HQ₅ and higher) could possibly erode even very old, well-consolidated and highlycontaminated sediments. The suspended matter of the high discharge events investigated (return periods of 15 to 20 years) exerted significantly higher cytotoxicity and mutagenicity than a moderate flood with a 1-year return period. These findings support the conclusion that the observed ecotoxicological effects during major floods may at least in part be due to the in-stream erosion of highly contaminated bottom sediments.     

Solving multidimensional bioeconomic problems with singular-perturbation reduction methods: Application to managing pest resistance to pesticidal crops

We investigate the application of ‘singular-perturbation’ reduction methods from the dynamical-systems literature to solve continuous-time multidimensional bioeconomic models resulting from integrating economics with increasingly complex biological structures. These methods reduce multidimensional solution space to the lower-dimensional subspace confining long-term dynamics. They arise naturally in problems with state variables evolving on widely disparate time scales. In particular, we demonstrate how the methods reduce the solution space of a linear-control specification—characterized by two state variables adjusting at widely disparate rates—to a single differential equation in the slow variable. All other system variables are determined by algebraic equations. We apply singular-perturbation methods to investigate the optimal management of pest resistance to pesticidal crops. The pest population evolves on a fast-time scale, while the population's genetic composition evolves on a slow-time scale. In comparison with past work, we can more fully characterize the continuous-time dynamics associated with a complex genetic specification.     

Species-specificity in trail pheromones and Dufour's gland contents ofCamponotus atriceps andC. floridanus (Hymenoptera: Formicidae)

Summary By means of gas chromatography, gas chromatographic coupled mass spectrometry, trail-following experiments and electrophysiological recordings from worker antennae, the major trail pheromone components from the hindgut of the formicine speciesCamponotus atriceps andC. floridanus were identified as 3,5-dimethyl-6-(1-methylpropyl)-tetrahydropyran-2-one and nerolic acid, respectively. The Dufour's gland contents of both species, investigated by gas chromatographic coupled mass spectrometry, show significant differences.Pheromones 104: Janssen E, Übler E, Bauriegel L, Kern F, Bestmann H-J, Attygalle AB, Steghaus-Kovacs S, Maschwitz U: Trail pheromone of the Ponerinae antLeptogenys peuqueti (Hymenoptera: Formicidae): a multicomponent mixture of related compounds     

Measurement of Odor-Plume Structure in a Wind Tunnel Using a Photoionization Detector and a Tracer Gas

The patterns of stimulus available to moths flying along pheromone plumes in a 3-m-long wind tunnel were characterized using a high frequency photoionization detector in conjunction with an inert tracer gas. Four contrasting flow regimes and source conditions were produced: odor released in pulses from a vertical and horizontal array of four sources, odor released continuously from a point source, and odor released continuously from a point source into an oscillatory wake. Although the four flow regimes produced plumes of intermittent and fluctuating concentration, there were considerable differences in the structure of the signal presented to the sensor. Pulses of tracer gas released at 10 Hz retained most of their longitudinal and lateral separation. The plume growing in the disturbed flow (`oscillatory'), was broader in its lateral extent than the plume growing in an undisturbed flow (`continuous'), and the concentrations in the former were lower at each downstream position. The signal recorded in the disturbed flow had higher intermittency, but the ratio between the peak concentration and the signal mean was lower than in the continuous plume. Time scales were typically longer in the tunnel than in a field setting, but length scales and the main features of intermittency and fluctuation were similar. Moths flying along plumes of pheromone in this and similar wind tunnels typically slow their velocity and narrow the lateral excursions of their flight track as they approach a pheromone source. Which features of the plumes measured in this study account for these behavioral reactions remains to be determined.