The computation of previously inaccessible digits of π² and Catalan's constant

We recently concluded a very large mathematical calculation, uncovering objects that until recently were widely considered to be forever inaccessible to computation. Our computations stem from the “BBP” formula for π, which was discovered in 1997 using a computer program implementing the “PSLQ” integer relation algorithm. This formula has the remarkable property that it permits one to directly calculate binary digits of π, beginning at an arbitrary position d, without needing to calculate any of the first d - 1 digits. Since 1997 numerous other BBP-type formulas have been discovered for various mathematical constants, including formulas for π² (both in binary and ternary bases) and for Catalan’s constant. In this article we describe the computation of base-64 digits of π², base-729 digits of π², and base-4096 digits of Catalan’s constant, in each case beginning at the ten trillionth place, computations that involved a total of approximately 1:549 x 1019 floating-point operations. We also discuss connections between BBP-type formulas and the age-old unsolved questions of whether and why constants such as π; π²; log 2, and Catalan’s constant have “random” digits

Utilization of a new bdelloid rotifer (Philodina acuticornis odiosa) assay to evaluate the effect of salinity on the toxicity of chlorothalonil

Acute (24 h) toxicity tests were conducted to determine the toxicity of the fungicide chlorothalonil towards the freshwater bdelloid rotifer (Philodina acuticornis odiosa). Since rotifers are the dominant zooplankton species in many inland freshwater lakes in Australia, the influence of salinity on chlorothalonil toxicty was also assessed. The rotifers used in this study appeared to be reasonably tolerant to changes in salinity, with little mortality observed at 3760 &micro;S cm-1, increasing thereafter at higher salinity. The bdelloid rotifers were, however, found to be highly sensitive to chlorothalonil (24 h LC50, 3.2 &micro;g L-1) with results also suggesting that as salinity increases, so does toxicity (e.g., 24 h LC50 at 5000 &micro;S cm-1, 0.5 &micro;g L-1). <br /

Effect of increasing salinity on the acute toxicity of a commercial endosulfan formulation to the bdelloid rotifer Philodina acuticornis odiosa

Pesticides, such as endosulfan, can enter surface waters such as lakes and rivers, potentially posing an ecological risk. Rotifers are a dominant zooplankton species in many inland freshwater lakes in Australia; such lakes can also experience increased salinities. Acute toxicity tests (24 h) were conducted to determine the toxicity of a commercial formaulation of endosulfan to the freshwater rotifer Philodina sp. and to investigate the influence of increasing salinity on endosulfan toxicity. Rotifers were found to be relatively tolerant to endosulfan with an EC50 of 1.75 mgL-1 (a.i.), with results also suggesting that there are no interactive effects of salinity on endosulfan toxicity

Ecotoxicity Thresholds for Ametryn, Diuron, Hexazinone and Simazine in Fresh and Marine Waters

Triazine and urea herbicides are two groups of photosystem II inhibiting herbicides frequently detected in surface, ground and marine waters. Yet, there are few water quality guidelines for herbicides. Ecotoxicity thresholds (ETs) for ametryn, hexazinone and simazine (triazine herbicides) and diuron (a urea herbicide) were calculated using the Australian and New Zealand method for deriving guideline values to protect fresh and marine ecosystems. Four ETs were derived for each chemical and ecosystem that should theoretically protect 99, 95, 90 and 80% of species (i.e. PC99, PC95, PC90 and PC80, respectively). For all four herbicides, the phototrophic species were significantly more sensitive than non-phototrophic species, and therefore, only the former data were used to calculate the ETs. Comparison of the ET values to measured concentrations in 2606 samples from 15 waterways that discharge to the Great Barrier Reef (2011–2015) found three exceedances of the simazine PC99, regular exceedances (up to 30%) of the PC99 in a limited number of rivers for ametryn and hexazinone and frequent (> 40%) exceedances of the PC99 and PC95 ETs in at least four waterways for diuron. There were no exceedances of the marine ETs in inshore reef areas. Further, ecotoxicity data are required for ametryn and hexazinone to fresh and marine phototrophic species, for simazine to marine phototrophic species, for tropical phototrophic species, repeated pulse exposures and long-term (2 to 12 months) exposures to environmentally relevant concentrations.Griffith Sciences, Griffith Institute for Drug DiscoveryNo Full Tex

Degradation of metalaxyl and folpet by filamentous fungi isolated from Portuguese (Alentejo) vineyard soils

Degradation of xenobiotics by microbial populations is a potential method to enhance the effectiveness of ex situ or in situ bioremediation. The purpose of this study was to evaluate the impact of repeated metalaxyl and folpet treatments on soil microbial communities and to select soil fungal strains able to degrade these fungicides. Results showed enhanced degradation of metalaxyl and folpet in vineyards soils submitted to repeated treatments with these fungicides. Indeed, the greatest degradation ability was observed in vineyard soil samples submitted to greater numbers of treatments. Respiration activities, as determined in the presence of selective antibiotics in soil suspensions amended with metalaxyl and folpet, showed that the fungal population was the microbiota community most active in the degradation process. Batch cultures performed with a progressive increase of fungicide concentrations allowed the selection of five tolerant fungal strains: Penicillium sp. 1 and Penicillium sp. 2, mycelia sterila 1 and 3, and Rhizopus stolonifer. Among these strains, mycelium sterila 3 and R. stolonifer presented only in vineyard soils treated with repeated application of these fungicides and showed tolerance >1,000 mg l−1 against commercial formulations of metalaxyl (10 %) plus folpet (40 %). Using specific methods for inducing sporulation, mycelium sterila 3 was identified as Gongronella sp. Because this fungus is rare, it was compared using csM13-polymerase chain reaction (PCR) with the two known species, Gongronella butleri and G. lacrispora. The high tolerance to metalaxyl and folpet shown by Gongronella sp. and R. stolonifer might be correlated with their degradation ability. Our results point out that selected strains have potential for the bioremediation of metalaxyl and folpet in polluted soil sites

Impacts of standard and `low environmental impact&#039; greywater irrigation on soil and plant nutrients and ecology

Interest in recycling greywaters is increasing as population growth, pollution and climate change increase pressure on water resources. There has been little research investigating impacts of irrigating untreated greywater on soil and plant health and to our knowledge no studies comparing greywater from standard with &quot;low environmental impact&quot; detergents. A soil-pot trial with lettuce and radish compared tap water, nutrient solution, and grey water (standard and minimal impact) irrigation. Greywater had impacts on plant biomass and nutrition, soil enzyme activity, and worm avoidance. In particular, there was little indication that the minimal impact greywater was safer for irrigation than the standard greywater. The minimal impact greywater was the only greywater treatment to have a significant negative impact on soil phosphatase activity and worm avoidance. The results highlight the need for greater understanding of the impacts of untreated greywater in irrigating vegetable gardens and especially when manufacturers make claims about the environmental friendliness of their products

Effect of increasing salinity on the toxicity of methidathion to freshwater rotifers (Philodina Acuticornis Odiosa)

Methidathion is used on fruit and vegetable crops and has been identified by regulators in Australia as potentially posing a risk to the environment. Further ecotoxicological data for methidathion are required to enable water quality trigger values to be derived for use in risk assessment. Rotifers are a dominant zooplankton species in many inland freshwater lakes in Australia; such lakes can also experience increased salinities. Acute toxicity tests (24-h) were conducted to determine the toxicity of methidathion to the freshwater rotifer Philodina acuticornis odiosa and to investigate the influence of increasing salinity on methidathion toxicity. Rotifers were found to be relatively tolerant to methidathion with a 24-h LC50 of 3.5 mg/L. Results also suggested that there are no interactive effects of salinity on methidathion toxicity

Assessing the performance of a bdelloid rotifer Philodina acuticornis odiosa acute toxicity assay

A bioassay using the bdelloid rotifer, Philodina acuticornis odiosa, was evaluated for use as a standard test method for direct toxicity assessment testing in the Australasian region. Philodina acuticornis odiosa was found to be relatively tolerant to phenol (24 h LC50, 142 mg/L). The mortality endpoint was both reliable and repeatable (the coefficients of variation for mortality at the 24 h LC50 concentration ranged from 11%-24% (n = 8)), sufficiently low to warrant further testing with a range of reference toxicants, so that this organism can be included for use as a regulatory test in Australasia

The Effects of Copper Hydroxide, Captan and Trifloxystrobin Fungicides on Soil Phosphomonoesterase and Urease Activity

There is increasing community awareness of the potential environmental risks posed by Cu-based fungicide use, which is placing increasing pressure on governments and industry to undertake risk minimisation action. However, if there is going to be a widespread move away from the use of Cu-based fungicides, logically there needs to be assurance that the alternatives pose a lower environmental risk. To that end, this study compared the effect of copper hydroxide, captan and trifloxystrobin on soil enzymatic (phosphomonoesterase and urease) activity. Compared to an untreated control, copper did not inhibit either enzyme activity, even at the highest dose used in the study (156\ua0mg/kg). At their respective high doses, captan (96\ua0mg/kg) and trifloxystrobin (144\ua0mg/kg) did not cause inhibition of phosphomonoesterase activity but did inhibit urease activity. Consequently, the results from this study suggest that the copper hydroxide alternatives, captan and trifloxystrobin, do not pose a short-term risk to P cycling processes in soil, although the results do suggest that these two are more toxic than copper hydroxide to N cycling processes in soil. Moreover, captan and trifloxystrobin compounds are unlikely to pose a long-term risk to soil microbial function as they are unlikely to persist in soil at concentrations found to cause an adverse effect on urease activity. Nonetheless, the potential disruption to N cycling processes needs to be recognised and consideration given to limiting the annual applications of these fungicides, particularly around the timing of repeat fungicide applications, to prevent accumulation of the fungicides in surface soils