Introduction To Probability and Statistical Decision Theory

A nonparametric sequential rank correlation test for independence consisting of a generalized sequential probability ratio test is investigated through the Monte Carlo method. The test is found to be satisfactory in terms of the power function. Comparison of the expected sample size of the test and three other tests including the fixed sample size test suggests that the sequential rank test is also efficient.     

How verified (or tested) is my code? Falsification-driven verification and testing

Formal verification has advanced to the point that developers can verify the correctness of small, critical modules. Unfortunately, despite considerable efforts, determining if a “verification” verifies what the author intends is still difficult. Previous approaches are difficult to understand and often limited in applicability. Developers need verification coverage in terms of the software they are verifying, not model checking diagnostics. We propose a methodology to allow developers to determine (and correct) what it is that they have verified, and tools to support that methodology. Our basic approach is based on a novel variation of mutation analysis and the idea of verification driven by falsification. We use the CBMC model checker to show that this approach is applicable not only to simple data structures and sorting routines, and verification of a routine in Mozilla’s JavaScript engine, but to understanding an ongoing effort to verify the Linux kernel read-copy-update mechanism. Moreover, we show that despite the probabilistic nature of random testing and the tendency to incompleteness of testing as opposed to verification, the same techniques, with suitable modifications, apply to automated test generation as well as to formal verification. In essence, it is the number of surviving mutants that drives the scalability of our methods, not the underlying method for detecting faults in a program. From the point of view of a Popperian analysis where an unkilled mutant is a weakness (in terms of its falsifiability) in a “scientific theory” of program behavior, it is only the number of weaknesses to be examined by a user that is important.     

TSTL: the template scripting testing language

International Journal on Software Tools for Technology Transfer - A test harness, in automated test generation, defines the set of valid tests for a system, as well as their correctness properties....     

Pesticide residues in foodstuffs in Great Britain: XII.—Organochlorine insecticide residues in hens' eggs from battery,deep-Utter and free-range systems and from houses containing insecticide thermal vaporisers

A study has been made of the organochlorine pesticide residues in hens' eggs produced in battery, deep-litter and free-range systems. Low residues (less than 0.05 ppm) were found except where the birds or their houses had been deliberately treated with pesticides to eradicate fleas or lice. A separate study was also made of eggs produced in houses which had insecticide thermal vaporisers installed in them. The results were variable, depending on a number of factors, but relatively high levels of BHC and DDT were found regularly in the eggs from some of these houses.     

Statewide investigation of the role of pyrethroid pesticides in sediment toxicity in California's urban waterways

A statewide investigation of urban creek sediment toxicity was conducted in California in recognition of increased incidences of toxicity linked to pyrethroid pesticides. The goals were to examine the spatial occurrence and magnitude of sediment toxicity in California urban creeks, and to examine the role of pyrethroids in toxic urban creek sediment samples. After a preliminary screening of 90 sites, 30 creeks were sampled in eight geographical regions. Sediment toxicity was assessed using 10 day bioassays with the resident amphipod Hyalella azteca. Bioassays were conducted at two test temperatures of 23 degrees C and at 15 degrees C to provide evidence of the cause of toxicity, and to more accurately reflect ambient environmental temperatures. Twenty-five of 30 samples were toxic when tested at 23 degrees C, and all 30 samples were toxic when tested at 15 degrees C. The magnitude of toxicity increased in samples tested at 15 degrees C suggesting the influence of pyrethroids, which are more toxic at colder temperatures. Pyrethroids were present in all sediment samples and were the only compounds detected at concentrations toxic to H. azteca. Bifenthrin was the pyrethroid of greatest toxicological concern, occurring in all 30 samples at concentrations up to 219 ng/g. Pyrethroid contamination of urban creeks was most severe in the Los Angeles, Central Valley, and San Diego regions, respectively. However, pyrethroids were also linked to urban creek aquatic toxicity in all regions sampled, including the less urbanized areas of the North Coast and Lake Tahoe.     

Enhanced microbial oil production by activated sludge microorganisms via co‐fermentation of glucose and xylose

The co‐fermentation of glucose and xylose by activated sludge microorganisms for the production of microbial oils for use as biodiesel feedstock was investigated. Various carbon sources at initial concentration of 60 g/L and C:N ratio 70:1 were investigated: xylose, glucose, and 2:1 and 1:2 (by mass) glucose/xylose mixtures. Oil accumulation ranged between 12 to 22% CDW, the highest of which was obtained when xylose was the sole substrate used. Kinetic modeling of the fermentation data showed that specific growth and oil accumulation rates were similar in all substrate types and the lipid coefficient ranged from 0.02 to 0.06 g/g of sugar consumed. The fatty acid methyl ester yield and composition of the lipids showed their suitability for conversion to biodiesel. Based on the results, lignocellulose sugars could be used as fermentation substrates by activated sludge microorganisms for enhancing the oil content of sewage sludge for its use as a sustainable biofuel feedstock source. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4036–4044, 2013     

Long term assessment of a hybrid electrochemical treatment

Monitoring the performance of systems installed to protect against/halt the corrosion of reinforcing steel in concrete is essential in ensuring that the reinforcing bar (rebar) is adequately protected and remains in a non‐corroding state. A chloride contaminated concrete test block containing a hybrid anode system has been periodically monitored over the past 4.5 years to assess the anode current output and thus, the protection offered to the steel. De‐polarisation and impedance analysis data have been acquired to calculate steel corrosion rates. Both tests indicated that the steel was passive in the concrete environment and that the anode was able to protect all of the embedded steel despite the difficult geometry of the sample. It was also found that after 2 years it was still possible to drive a high current from the installed anode.