This study examines children’s perceptions of their experiences in two science-oriented multiuser virtual environments (MUVEs), River City and Whyville. Sixth-grade students were asked how they would rate and compare different features of these environments. The children rated River City as providing greater educational benefits but preferred communicating with real people in Whyville as oppose...

In 2000, 2001, and 2002, blood and feather samples were collected from 40-45-day-old nestling ospreys (Pandion haliaetus) from Chesapeake Bay and Delaware Bay and River. Concentrations of 18 metals, metalloids, and other elements were determined in these samples by inductively coupled plasma-mass spectroscopy, and Hg concentrations were measured by cold vapor atomic absorption spectroscopy. Whe...

The kinetics of polychlorinated biphenyl (PCB) dechlorination by Hudson River (New York, USA) sediment microorganisms were investigated using Aroclor 1242 at 10 concentrations ranging from 0 to 900 ppm (0-11.2 micromol Cl/g sediment). The time course of PCB dechlorination and population growth were determined by congener-specific analysis and the most-probable-number technique, respectively, ov...

drought is a complex natural phenomenon that can occur in any climate. hydrologic drought in the river flow of arid and semi-arid areas causes serious shortages, threatens the quality of life, and impacts on the economy. understanding this feature is then essential for the management of water resources. hydrologic drought in the sense of deficient river flow is defined as the periods that river...

Cholera is a contagious acute diarrheal disease due to ingestion of contaminated water and food with Vibrio cholera, Gram-negative bacterium that naturally inhabits coastal estuarine ecosystems. Millions cholera cases thousands deaths are annually reported worldwide. endemic in Iraq every 3-5 years interval. Meanwhile, outbreaks have been reporting Kurdistan region. However, the epidemiology ha...

Ammonium (NH4 ), nitrate+nitrite (NOx), dissolved inorganic phosphorus (DIP) and dissolved organic carbon, nitrogen and phosphorus (DOC, DON and DOP) were measured in the Altamaha River and several tributaries during a two year period from September 2000 through September 2002. Temporal variations in concentration as well as nutrient and dissolved organic matter loading from the Altamaha to the...

  Various parasite species were found in Carassius carassius including Diplostomum spathaceum, Dactylogyrus sp.,Gyrodactylus sp. Ichthyophthirius multifiliis and Trichodinia sp . They were found in four rivers in West Azerbaijan Province (North-Western Iran) . A total of 207 live Carassius carassius from four rivers including Aras (72) Zariyneh (42) Nazlo (58) and Barandoz (35) were studied. Pa...

In an actively deforming orogen, maintenance of a topographic steady state requires that hillslope erosion, river incision, and rock uplift rates are balanced over timescales of 10–10 years. Over shorter times, < 10 years, hillslope erosion and bedrock river incision rates fluctuate with changes in climate. On 10-year timescales, the Marsyandi River in the central Nepal Himalaya has oscillated ...