Established Testing Procedures Research Articles

A multiparameter chemical toxicity test using Salmonella typhimurium and Spirochaeta aurantia

AbstractA battery of measurements, including specific growth rate, intracellular ATP level, and respiration rate, was designed to measure the responses of Salmonella typhimurium and Spirochaeta aurantia to chemical toxicants. The test battery provided both a measure of relative toxicity and an indication of the biochemical mechanism of chemical toxicity.The utility of the battery was investigated using chemicals (cyanide, 2,4‐dinitrophenol, chloramphenicol, and dicyclohexylcarbodiimide) for which toxic mechanisms have been clearly established. Test battery results provided a reproducible “signature” for each model compound, which was useful for differentiating among compounds whose primary mechanism of toxicity involves (a) inhibition of catabolic activity leading to oxidative phosphorylation, (b) disruption of membrane integrity, and (c) interference with biosynthetic activity. The responses of the two test organisms to model inhibitors were qualitatively identical and paralleled predictions based on theoretical grounds.In theory, the test battery can measure toxicity among classes of compounds that alternative, single‐parameter microbial tests would classify as nontoxic. The microbial test battery described may eventually provide a theoretically superior and economically attractive alternative to established toxicity testing procedures.

Standardizing Measurement of Rheological Properties of Cooked Russet Burbank Potatoes

ABSTRACT POTATOES are a staple food in the United States and many other countries. Russet Burbank is the principal potato cultivar processed commercially in the United States. Because texture and flavor of cooked potatoes are important attributes that affect consumer acceptance and because flavor can be modified by seasonings, cooked potato texture is the critical attribute that needs to be controlled to meet consumer satisfaction. Knowledge of basic engineering properties of potatoes offers potential for developing controls to consistently acheive desirable cooked potato texture. Raw product engineering properties related by reaction kinetic relationships to cooked product properties can provide the needed mechanism for predicting proper processing conditions. Then fundamental properties of the cooked potatoes, a measure of the processed product quality, can provide feedback control for processing operations. Fundamental engineering properties of cooked potatoes are loading-rate dependent; therefore, they are called rheological properties. Rheological properties of cooked potatoes are affected by within-tuber, among-tuber, and cooking-time variations (Davis et al., 1983; Leung et al., 1983). Large variations in reported values indicate that standard test conditions must be established before consistent results can be obtained and before useful comparisons can be made among research results. The purpose of this research was to establish standard procedures for measuring rheological properties of cooked Russet Burbank potatoes. Specific objectives were to: 1. Determine the effects of tuber variability and testing procedures on measured rheological parameters, and 2. Establish testing procedures that minimize measurment variability

Toxicity of arsenite and arsenate to the marine macroalga Champia Parvula (rhodophyta)

AbstractBy a previously established test procedure that uses 4.5 μM phosphate in the medium, the marine red alga Champiaparvula (C. Agardh) Harvey was shown to be more sensitive to arsenite [As(III)] than to arsenate [As(V)]. Mature cystocarps (evidence of sexual reproduction) were formed when plants were exposed to 65 μg As(III)/L, but not when exposed to 95 μg As(III)/L. Three hundred micrograms As(III)/L was sufficient to kill C. parvula. Using the standardized test, plants grew just as well in 10,000 μg As(V)/L as they did in the controls; however, sexual reproduction did not occur at this concentration. Phosphate concentration up to 9.1 μM had little or no effect on As(III) toxicity. Arsenate toxicity, however, was inversely proportional to the amount of phosphate in the medium. In the absence of added phosphate, As(V) toxicity was similar to that of As(III), except plants were still alive at 1,076 μg As(V)/L (although they did not grow).

A Test of Independence against a Class of Ordered Alternatives in a 2 ×CContingency Table

Abstract A likelihood ratio statistic is derived for testing the hypothesis of independence in a 2 × C table against a class of ordered alternatives defined in terms of cross-product ratios. Asymptotic equivalence on the null hypothesis to a chi-squared—type statistic is established. The large-sample distribution of these statistics depends on the column totals, but numerical evidence for C = 3 and 4 suggests that the exact size of a test derived by ignoring this dependency will remain within reasonable limits for a wide range of tables encountered in practice. Some power comparisons with established test procedures are reported.

Testing Structural Specification Using the Unrestricted Reduced Form

In the first section of this paper the overidentifying restrictions on a system of linear simultaneous equations are expressed in terms of restrictions on the reduced form parameters. These restrictions provide the basis of a test of the structure using only the unrestricted reduced form parameter estimates. Under Ho the test proposed is asymptotically equivalent to a likelihood ratio test. The test may be applied as a single equation or complete system procedure and it may be presented as either a x2 or an F statistic. The case is also made here for system overidentification tests rather than single equation procedures, the arguments being drawn from the statistical literature on hypothesis testing by induction. The computational advantages of the present proposals are substantial when compared to FIML based likelihood -ratio tests and Monte Carlo experiments confirm that a system version of the test performs well in large samples. The system version of the test behaves like the FIML likelihood ratio test in large sample situations both under Ho and H1. However, the Monte Carlo studies indicate that both the single equation and system versions of the test perform poorly in small samples. THE AIM OF THIS paper is to investigate the possibility of deciding on the specification of a simultaneous equation model prior to the estimation of the structure. A well established test procedure is suggested which uses OLS estimates of the reduced form parameters; it enables the null hypothesis, that the model specified is not significantly different from the model which generated the sample, to be tested. Because of the one-to-one correspondence between the overidentified structure and the restricted reduced form, it is possible to make inferences about the structure from the observed compatibility of the reduced form restrictions with the sample information. In addition, the reduced form restrictions resulting from a particular equation may be isolated and tested separately, if desired. The principle underlying the test would appear to be due to Wald [17J; namely, that if the null hypothesis is correct and the structure postulated as the maintained hypothesis was responsible for the generation of the observed sample, then the unrestricted reduced form parameter estimates will tend, if the sample size is large enough, to satisfy the reduced form restrictions advanced under the maintained hypothesis. A number of problems relating to identification of linear simultaneous equations make life a little difficult and are discussed subsequently. Now, take the linear structure

Assessment of the phosphorus and sulphur status of subterranean clover pastures. 2. Soil tests

Values obtained by a number of established soil test procedures for phosphorus and sulphur were correlated with yield responses to addition of the relevant nutrient, by subterranean clover-based pastures at 21 sites in south-eastern New South Wales. Colwell's bicarbonate-soluble P and Bray's P, phosphorus values showed sufficiently close associations with response to added phosphorus to be useful for predictive purposes ; Bray's P, values generally gave smaller coefficients. In general, the pasture on soils testing less than 25 p.p.m. bicarbonate-extractable P in the surface three inches responded appreciably to applied phosphorus (relative yields were <85 per cent). The corresponding value for the Bray P, procedure was 10 p.p.m. P. Soil samples from 0-1, 0-3, and 3-6 inch depths gave similar correlations with response. The time of soil sampling did not affect the relationships but winter pasture production was not as closely related to soil test values as was spring production. By contrast, soil tests for sulphur were not reliable but some discrimination between soils could be made with a 500 p.p.m. phosphate extraction. Values from soil samples collected in the winter were less closely related to response than were values from samples collected in the autumn.

THE 131-I-TRIIODOTHYRONINE-RESIN UPTAKE TEST.

SUMMARY The results of 450 131I-triiodothyronine (T3)-resin uptake tests in euthyroid, hyper- and hypothyroid patients are described. The effects of variation in the temperature and weight of resin on 131I-T3 uptake are demonstrated. Limits of normality have been established for a group of 149 euthyroid patients. The 131I-T3-resin uptake test in euthyroid, hyper- and hypothyroid patients has been compared with the 4 and 48 hr. 131I neck uptake, the protein-bound iodine (p.b.i.) concentration and the basal metabolic rate (b.m.r.) as a test of thyroid status. The results suggest that, as a single test for the estimation of thyroid status, the 131I-T3-resin uptake test is as reliable and more convenient than the more established test procedures.

A new collector of solar radiant energy—Theory and experimental verification

An effective quality control is essential for a large-scale dissemination of solar thermal technologies on the products being offered by the industry to the end users. For this, there is a need to establish test procedures and methodologies for producing performance characteristic parameters, which could provide an equitable basis for comparison of performances of these products. At present, paraboloid concentrator type solar cooker technology is moving towards the phase of commercialization in India. For the thermal performance evaluation of paraboloid concentrator type solar cooker, Mullick et al. (1991) developed a test procedure that essentially recommends determination of optical efficiency factor (F′ηo) and heat loss factor (F′UL) based on heating and cooling tests. Further a test method has been proposed by Funk (2000) for testing of all kind of solar cookers that characterizes the performance of solar cooker by two parameters, namely, adjusted cooking power (Pa) and overall heat loss coefficient (UL) as obtained from heating test. These are the only test methods available for testing of paraboloid concentrator type solar cooker.The present communication analyzes the effect of instrumentation, on the values of F′ηo, F′UL, Pa and UL, which is supported by a large number of outdoor tests conducted on a paraboloid concentrator type solar cooker under heating and cooling test conditions. The role of individual associated parameters on F′ηo, F′UL, Pa and UL has been analyzed along with the estimation of overall error in these values due to the error in the determination of associated parameters. Though the maximum attainable accuracy in determining F′UL varies from 1.15% to 0.65% (for loads of 1.0 to 8.0 kg), the associated error in the determination of F′ηo is quite high viz. 5.13% to 5.04% for the same load conditions. Similarly, the maximum attainable accuracy in the determination of standardized cooking power has been observed from 4.98% to 5.02% under the load conditions from 1.0 to 8.0 kg.

The distribution of solar radiation over the earth's surface : Black, J. N. Arch. Meteor. Geophys. Bioklimatol. B, 7(2): 165–189, 1956

An effective quality control is essential for a large-scale dissemination of solar thermal technologies on the products being offered by the industry to the end users. For this, there is a need to establish test procedures and methodologies for producing performance characteristic parameters, which could provide an equitable basis for comparison of performances of these products. At present, paraboloid concentrator type solar cooker technology is moving towards the phase of commercialization in India. For the thermal performance evaluation of paraboloid concentrator type solar cooker, Mullick et al. (1991) developed a test procedure that essentially recommends determination of optical efficiency factor (F′ηo) and heat loss factor (F′UL) based on heating and cooling tests. Further a test method has been proposed by Funk (2000) for testing of all kind of solar cookers that characterizes the performance of solar cooker by two parameters, namely, adjusted cooking power (Pa) and overall heat loss coefficient (UL) as obtained from heating test. These are the only test methods available for testing of paraboloid concentrator type solar cooker.The present communication analyzes the effect of instrumentation, on the values of F′ηo, F′UL, Pa and UL, which is supported by a large number of outdoor tests conducted on a paraboloid concentrator type solar cooker under heating and cooling test conditions. The role of individual associated parameters on F′ηo, F′UL, Pa and UL has been analyzed along with the estimation of overall error in these values due to the error in the determination of associated parameters. Though the maximum attainable accuracy in determining F′UL varies from 1.15% to 0.65% (for loads of 1.0 to 8.0 kg), the associated error in the determination of F′ηo is quite high viz. 5.13% to 5.04% for the same load conditions. Similarly, the maximum attainable accuracy in the determination of standardized cooking power has been observed from 4.98% to 5.02% under the load conditions from 1.0 to 8.0 kg.