Integration-free interval doubling for Riccati equation solutions

Various algorithms are given for the case of constant coefficients. The algorithms are based on two ideas: first, relate the Re solution with general initial conditions to anchored RE solutions; and second, when the coefficients are constant the anchored solutions have a basic shift-invariance property. These ideas are used to construct an integration free superlinearly convergent iterative solution to the algebraic RE. The algorithm, arranged in square-root form, is thought to be numerically stable and competitive with other methods of solving the algebraic RE

Electrostatics of Colloidal Particles Confined in Nanochannels: Role of Double-Layer Interactions and Ion-Ion Correlations

We perform computational investigations of electrolyte-mediated interactions of charged colloidal particles confined within nanochannels. We investigate the role of discrete ion effects, valence, and electrolyte strength on colloid-wall interactions. We find for some of the multivalent charge regimes that the like-charged colloids and walls can have attractive interactions. We study in detail these interactions and the free energy profile for the colloid-wall separation. We find there are energy barriers and energy minima giving preferred colloid locations in the channel near the center and at a distance near to but separated from the channel walls. We characterize contributions from surface overcharging, condensed layers, and overlap of ion double-layers. We perform our investigations using Coarse-Grained Brownian Dynamics simulations (BD), classical Density Functional Theory (cDFT), and mean-field Poisson-Boltzmann Theory (PB). We discuss the implications of our results for phenomena in nanoscale devices.Comment: 23 figure

Decay of Escherichia Coli in Biosolids Applied to Agricultural Soil

There is little scientific data available on the survival patterns of pathogenic microorganisms introduced into the soil through the broad acre application of biosolids. This study was conducted to investigate the decay rates of Escherichia coli in agricultural soil amended with biosolids during two different growing seasons in a dry temperature cropping region in Western Australia.Biosolids-amended and unamended soil were inoculated with E. coli (ACM 1803), inserted into sentinel chambers and placed into the topsoil (0-10 cm) of a wheat crop. Biosolids were applied to designated biosolids plots, according to normal district practice, and E. coli numbers within the sentinel chambers were monitored over time. E. coli numbers in biosolids-amended soil reached detection limits (>10 cfu/mL) within 6 to 7 months. The decay patterns of E. coli, by treatment difference (biosolids-amended or unamended), linear and quadratic relationships of sampling time, and their interactions were highly significant. The T90 or time taken for a 90% reduction in numbers in the biosolids-amended soil was estimated to be 74, 143, 183 days (2006) and 173, 211 days (2008) as compared with 188 days (2006) and 156, 242 days (2008) in the unamended soil. This research provides scientific data on the survival times of E. coli in agricultural soil, with and without biosolids and can thus be helpful to public health policy

Decay of human enteric pathogens in agricultural soil amended with biosolids: Key findings from a comprehensive research project to examine potential health risks.

A comprehensive study was undertaken to examine the survival potential of enteric microorganisms in biosolids-amended soil, wheat plant phyllosphere, and stored grains. The presence of these microorganisms in the dust at harvesting time was also evaluated. In situ field experiments were conducted to examine the decay of E. coli (indicator bacteria), Salmonella enterica, bacteriophage MS2 and human adenovirus in biosolids-amended soils and in dust generated during harvesting of wheat. Glasshouse experiments were conducted to determine the survival potential of enteric microorganisms in the wheat phyllosphere and stored grains to determine any possible risks to humans or livestock through consumption of contaminated grains or fodder. The results of this study suggest that the target microorganisms decayed faster in the biosolids-amended soil compared with the unamended soil in the field, that the decay times were specific to the microorganism type; and that microorganism decay was correlated to declining soil moisture levels and increasing soil temperature. The risk of transmission of disease-causing microorganisms (human pathogens) from cereal crops fertilised with biosolids was considered to be low

Distributions of fecal markers in wastewater from different climatic zones for human fecal pollution tracking in Australian surface waters

Recreational and potable water supplies polluted with human wastewater can pose a direct health risk to humans. Therefore, sensitive detection of human fecal pollution in environmental waters is very important to water quality authorities around the globe. Microbial source tracking (MST) utilizes human fecal markers (HFMs) to detect human wastewater pollution in environmental waters. The concentrations of these markers in raw wastewater are considered important because it is likely that a marker whose concentration is high in wastewater will be more frequently detected in polluted waters. In this study, quantitative PCR (qPCR) assays were used to determine the concentrations of fecal indicator bacteria (FIB) Escherichia coli and Enterococcus spp., HFMs Bacteroides HF183, human adenoviruses (HAdVs), and polyomaviruses (HPyVs) in raw municipal wastewater influent from various climatic zones in Australia. E. coli mean concentrations in pooled human wastewater data sets (from various climatic zones) were the highest (3.2 × 10 gene copies per ml), followed by those of HF183 (8.0 × 10 gene copies per ml) and Enterococcus spp. (3.6 × 10 gene copies per ml). HAdV and HPyV concentrations were 2 to 3 orders of magnitude lower than those of FIB and HF183. Strong positive and negative correlations were observed between the FIB and HFM concentrations within and across wastewater treatment plants (WWTPs). To identify the most sensitive marker of human fecal pollution, environmental water samples were seeded with raw human wastewater. The results from the seeding experiments indicated that Bacteroides HF183 was more sensitive for detecting human fecal pollution than HAdVs and HPyVs. Since the HF183 marker can occasionally be present in nontarget animal fecal samples, it is recommended that HF183 along with a viral marker (HAdVs or HPyVs) be used for tracking human fecal pollution in Australian environmental waters

A general strategy for discovery of inhibitors and activators of RING and U-box E3 ligases with ubiquitin variants

RING and U-box E3 ubiquitin ligases regulate diverse eukaryotic processes and have been implicated in numerous diseases, but targeting these enzymes remains a major challenge. We report the development of three ubiquitin variants (UbVs), each binding selectively to the RING or U-box domain of a distinct E3 ligase: monomeric UBE4B, phosphorylated active CBL, or dimeric XIAP. Structural and biochemical analyses revealed that UbVs specifically inhibited the activity of UBE4B or phosphorylated CBL by blocking the E2∼Ub binding site. Surprisingly, the UbV selective for dimeric XIAP formed a dimer to stimulate E3 activity by stabilizing the closed E2∼Ub conformation. We further verified the inhibitory and stimulatory functions of UbVs in cells. Our work provides a general strategy to inhibit or activate RING/U-box E3 ligases and provides a resource for the research community to modulate these enzymes

Near simultaneous measurements of NO2 and NO3 over tropics by ground-based absorption spectroscopy

The present study concentrates on measurements of NO2 and NO3. NO2 has been measured during twilight period using zenith sky absorption spectrometric technique in the 436 to 448 nm region. NO3 has been measured during night time using direct moon as a source of light in the 655 to 667 nm region. These measurements have been taken at low latitude station, Ahmedabad (23 deg N, 76 deg E), India for the past two years

Combustion waves in a model with chain branching reaction and their stability

In this paper the travelling wave solutions in the adiabatic model with two-step chain branching reaction mechanism are investigated both numerically and analytically in the limit of equal diffusivity of reactant, radicals and heat. The properties of these solutions and their stability are investigated in detail. The behaviour of combustion waves are demonstrated to have similarities with the properties of nonadiabatic one-step combustion waves in that there is a residual amount of fuel left behind the travelling waves and the solutions can exhibit extinction. The difference between the nonadiabatic one-step and adiabatic two-step models is found in the behaviour of the combustion waves near the extinction condition. It is shown that the flame velocity drops down to zero and a standing combustion wave is formed as the extinction condition is reached. Prospects of further work are also discussed.Comment: pages 32, figures 2

Global occurrence of Torque teno virus in water systems

Bacterial indicator organisms are used globally to assess the microbiological safety of waters. However, waterborne viral outbreaks have occurred in drinking water systems despite negative bacterial results. Using viral markers may therefore provide more accurate health risk assessment data. In this study, fecal, wastewater, stormwater, surface water (fresh and salt), groundwater, and drinking water samples were analyzed for the presence or concentration of traditional indicators, innovative indicators and viral markers. Samples were obtained in the United States, Italy, and Australia and results compared to those reported for studies conducted in Asia and South America as well. Indicators included total coliforms, Escherichia coli, enterococci, male-specific coliphages, somatic coliphages and microviradae. Viral markers included adenovirus, polyomavirus, and a potential new surrogate, Torque teno virus (TTV). TTV was more frequently found in wastewaters (38-100%) and waters influenced by waste discharges (25%) than in surface waters used as drinking water sources (5%). TTV was also specific to human rather than animal feces. While TTV numbers were strongly correlated to other viral markers in wastewaters, suggesting its utility as a fecal contamination marker, data limitations and TTV presence in treated drinking waters demonstrates that additional research is needed on this potential viral indicator