Benchmarking a Light-Curve Model at Low-z

A set of well-measured, {low-z}, type Ia supernovae from the Calán/Tololo SNe data sets is used to determine benchmark parameters in our hydrodynamics-based, light-curve model. The light-curve data fit fairly well in B, V, and R passbands but not as well in the I passband. The fitting procedure, extracted best-fit model parameters, and their connection to type Ia SN parameters are presented. Our benchmarked light-curve model represents an alternative to empirical template methods for the analysis of light-curve data.     

Acceleration of black hole universe

Recently, Zhang slightly modified the standard big bang theory and developed a new cosmological model called black hole universe, which is consistent with Mach’s principle, governed by Einstein’s general theory of relativity, and able to explain all observations of the universe. Previous studies accounted for the origin, structure, evolution, expansion, and cosmic microwave background radiation of the black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This paper investigates acceleration of the black hole universe and provides an alternative explanation for the redshift and luminosity distance measurements of type Ia supernovae. The results indicate that the black hole universe accelerates its expansion when it accretes the ambient matter in an increasing rate. In other words, i.e., when the second-order derivative of the mass of the black hole universe with respect to the time is positive $\ddot{M}(t) > 0$ . For a constant deceleration parameter $q = -M(t) \ddot{M}(t)/\dot{M}(t) \sim-0.6$ , we can perfectly explain the type Ia supernova measurements with the reduced chi-square to be very close to unity, χ _red～1.0012. The expansion and acceleration of black hole universe are driven by external energy.     

Evaluation of an empirical orthogonal function–based method to downscale soil moisture patterns based on topographical attributes

Soil moisture influences many hydrologic applications including agriculture, land management and flood prediction. Most remote‐sensing methods that estimate soil moisture produce coarse resolution patterns, so methods are required to downscale such patterns to the resolutions required by these applications (e.g. 10‐ to 30‐m grid cells). At such resolutions, topography is known to affect soil moisture patterns. Although methods have been proposed to downscale soil moisture based on topography, they usually require the availability of past high‐resolution soil moisture patterns from the application region. The objective of this article is to determine whether a single topographic‐based downscaling method can be used at multiple locations without relying on detailed local observations. The evaluated downscaling method is developed on the basis of empirical orthogonal function (EOF) analysis of space–time soil moisture data at a reference catchment. The most important EOFs are then estimated from topographic attributes, and the associated expansion coefficients are estimated on the basis of the spatial‐average soil moisture. To test the portability of this EOF‐based method, it is developed separately using four data sets (Tarrawarra, Tarrawarra 2, Cache la Poudre and Satellite Station), and the relationships that are derived from these data sets to estimate the EOFs and expansion coefficients are compared. In addition, each of these downscaling methods is applied not only for the catchment where it was developed but also to the other three catchments. The results suggest that the EOF downscaling method performs well for the location where it is developed, but its performance degrades when applied to other catchments. Copyright © 2011 John Wiley & Sons, Ltd.     

Respiratory response of cunners to silver

Cunners, a common inshore teleost fish of the north-east coast of the United States, were exposed to various concentrations of silver for 96 h. At the end of this exposure period measurements of gill-tissue oxygen consumption were made. Significant respiratory depression was noted after exposure to concentrations as low as 0.12 ppm. These results are compared to those of similar studies using cadmium and mercury as the test metals.     

Responses of tidal creek macrobenthic communities to the effects of watershed development

This study examined the effects of watershed development on macrobenthic communities in tidal creeks of Charleston Harbor, South Carolina, U.S. Two types of creeks were evaluated: upland creeks which drained watersheds consisting of at least 15% terrestrial land cover, and salt marsh creeks which drained no upland habitat (i.e., only intertidal habitat). Samples of macrobenthic organisms were taken along the longitudinal axis of twenty-three primary (first order) tidal creeks. Water and sediment quality data were also collected including measurements of dissolved oxygen, salinity, temperature, sediment characteristics, and toxic chemicals in the creek sediments. Hypoxic conditions occurred more than 15% of the time in both reference and developed creeks and were a natural attribute of these systems. The most severe and frequent hypoxia occurred in impacted salt marsh creeks. Salinity fluctuations were the greatest in developed upland creeks and salinity range was identified as a potentially reliable indicator of the degree to which watershed development has altered hydrodynamic processes. The creeks draining urban and industrial watersheds were degraded environments characterized by watersheds with high (>50%) levels of impervious surface, broad fluctuations in salinity, severe hypoxia, and potentially toxic levels of chemicals in the sediment. These creeks had low macrobenthic diversity and abundance and were numerically dominated by the oligochaeteMonopylephorus rubroniveus in mud sediments, and the polychaeteLaeoreis culveri in sand sediments. Suburban watersheds had 15–35% impervious surface and creeks draining them were exposed to frequent hypoxia and broad salinity fluctuations. The levels of chemical contaminants in sediments of suburban and impacted salt marsh creeks were generally not different from the levels in reference creeks. Macrobenthic diversity and abundance were higher for suburban and impacted salt marsh creeks than for urban and industrial creeks. However, suburban and salt marsh impacted creeks were numerically dominated by a few pollution indicative species including the oligochaetesM. rubroniveus andTubificoides brownae and the polychaeteL. culveri. These creeks appear to be exhibiting early signs of degradation (e.g., a simplified food web). Two promising community-level macrobenthic metrics for assessing environmental quality were identified: the proportional abundance of pollution indicative taxa, and the proportional abundance of pollution sensitive taxa. These indicators were significantly (p<0.05) correlated with the salinity range, the level of chemical contaminants in sediments, and amount of impervious surface in the watershed.     

Prediction of acid mine drainage generation potential in selected mines in the Ashanti Metallogenic Belt using static geochemical methods

Acid mine/rock drainage (AMD/ARD) is the biggest environmental threat facing the mining industry. This study investigates AMD/ARD possibilities in three mines in the Ashanti Belt, using acid base accounting (ABA) and net acid generation pH (NAGpH) tests. Twenty-eight samples of rock units and mine spoil from these mines were collected for ABA and NAGpH tests. Two tailing dumps at Prestea and Nsuta were confirmed by both methods as acid generating with NAGpH of 4.5 and 4.6 and neutralization potential ratio values of 4.38 and 4.60, respectively. Six other samples are classified as potentially acid generating using a variety of established classification criteria. The rest of the samples either exhibited very low sulphur and carbonate content or had excess carbonate over sulphur. Consistency between results from ABA and NAGpH tests validates these tests as adequate tools for preliminary evaluation of AMD/ARD possibilities in any mining project in the Ashanti Belt.     

Annual estimates of water and solute export from 42 tributaries to the Yukon River

Annual export of 11 major and trace solutes for the Yukon River is found to be accurately determined based on summing 42 tributary contributions. These findings provide the first published estimates of tributary specific distribution of solutes within the Yukon River basin. First, we show that annual discharge of the Yukon River can be computed by summing calculated annual discharges from 42 tributaries. Annual discharge for the tributaries is calculated from the basin area and average annual precipitation over that area using a previously published regional regression equation. Based on tributary inputs, we estimate an average annual discharge for the Yukon River of 210 km³ year^–1. This value is within 1% of the average measured annual discharge at the U.S. Geological Survey gaging station near the river terminus at Pilot Station, AK, for water years 2001 through 2005. Next, annual loads for 11 solutes are determined by combining annual discharge with point measurements of solute concentrations in tributary river water. Based on the sum of solutes in tributary water, we find that the Yukon River discharges approximately 33 million metric tons of dissolved solids each year at Pilot Station. Discharged solutes are dominated by cations calcium and magnesium (5.65 × 10⁹ and 1.42 × 10⁹ g year^–1) and anions bicarbonate and sulphate (17.3 × 10⁹ and 5.40 × 10⁹ g year^–1). These loads compare well with loads calculated independently at the three continuous gaging stations along the Yukon River. These findings show how annual solute yields vary throughout a major subarctic river basin and that accurate estimates of total river export can be determined from calculated tributary contributions. Copyright © 2011. This article is a U.S. Government work and is in the public domain in the USA.