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Difference Tests (difference + test)
Kinds of Difference Tests Selected AbstractsSeedling Growth of Agronomic Crops in Crude Oil Contaminated SoilJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2006I. Issoufi Abstract Phytoremediation of hydrocarbon-contaminated soil shows promise as a low-cost alternative to most remediation methods. This study evaluated seedling growth of six crop species in crude oil contaminated soils. The experiments were conducted in a greenhouse. Weathered crude oil was added to an Ipava silt loam soil at the rate of 0 (control), 10, 50 and 100 g of crude oil kg,1 of soil, which was then placed into pots. Irrigation was used to maintain soil moisture at approximately field capacity. Five seeds of Zea mays, Meticago sativa, Lolium perenne, Triticum aestivum, Glycine max or Vicia villosa were sown per pot. The experimental design was completely randomized with five replications per treatment. Germination and seedling height data were recorded on day 7, 14, 21 and 28. Plants were harvested on day 28, separated into shoots and roots and dried to measure biomass. Analysis of variance was used to determine treatment significance. Significant treatment mean values were separated using Tukey's Honestly Significant Difference Test. Based upon percent emergence and plant biomass production in contaminated soil, Z. mays and G. max seedlings show the greatest potential to enhance remediation. [source] Microtensile Bond Strength of Luting Materials to Coronal and Root DentinJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 3 2005RICARDO WALTER DDS ABSTRACT Purpose:: The purpose of this study was to evaluate the microtensile bond strength (,TBS) of two dual-cured resin cements and a glass ionomer cement to coronal dentin versus root dentin. Materials and Methods: RelyX Unicem (3M ESPE, St. Paul, MN, USA) and Panavia F (Kuraray Medical Inc., Tokyo, Japan) were the resin cements used and FujiCEM (GC Corp., Tokyo, Japan) was the glass ionomer cement used. Once separated, the labial coronal and root surfaces of six bovine incisors were ground with 600-grit SiC papers to expose middle dentin. Then, the dentin surfaces were treated following the manufacturers'instructions and a 1 mm thick layer of each material was applied to the flattened coronal and root surfaces. Each material was cured following the manufacturers'recommendations and a composite buildup was made over the cured luting materials for testing purposes. After 24 hours in water at 37°C, the teeth were sectioned into 1 mm × 1 mm × 6 mm beams and tested for ,TBS. The data were analyzed by one- and two-way analysis of variance and Fisher's Protected Least Squares Differences test (p < .05). Results: The ,TBSs to coronal and root dentin were similar within each cement. Comparing the materials, RelyX Unicem presented the highest ,TBS, followed by Panavia F and FujiCEM, respectively (p < .0001). Conclusions: Although there were differences in ,TBS among the materials tested, no significant differences were found between bond strengths to coronal and root substrates. [source] Recovery of,Salmonella enterica,Serovars Typhimurium and Tennessee in Peanut Butter after Electron Beam ExposureJOURNAL OF FOOD SCIENCE, Issue 7 2010Kristen E. Matak Abstract:, The effect of electron beam (e-beam) radiation on the recovery of,Salmonella,serotypes Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter over a 14-d storage period at 22 °C was studied. Each,Salmonella,type was independently inoculated into peanut butter and subjected to e-beam doses that ranged from 0 to 3.1 kGy, confirmed by film dosimetry. After 2-, 4-, 6-, 8-, and 14-d of storage, microbial analyses were conducted. Survivors were recovered on growth and selective media using standard spread-plating methods. Microbial counts (CFU/g) were log-converted and differences were determined by ANOVA and Tukey's Honestly Significant Differences test. When samples were not e-beam-treated, there were no significant changes (P,> 0.05) in microbial numbers over time. In e-beamed samples, microbial numbers decreased over time; however, reductions were not always significant. Initial recovery rates (R-rates) 2 d after e-beam treatment were significantly different for the 2 strains of,Salmonella,and between recovery media (P,< 0.05); however, these differences did not persist for the remainder of the storage period (P,> 0.05) indicating that injured cells were not able to survive in the high-fat, low-water activity peanut butter environment. R-rates for both strains of,Salmonella,were maintained until day 14 when there were significant reductions in,Salmonella,Typhimurium (P,< 0.05). These results indicate that,Salmonella,Tennessee and,Salmonella,Typhimurium will survive in peanut butter when exposed to nonlethal doses of e-beam irradiation. Practical Application: Electron beam (e-beam) irradiation is an alternative to thermal processing; this technique inactivates microorganisms and insects that might be present in a food by generating radiation by accelerated electrons that inactivate organisms directly because of interaction with cell components and indirectly by producing free radicals that disrupt integrity of the cell membrane. E-beam radiation will reduce the number of probable microbiological hazards that could be present while the food remains generally unaffected in texture, taste, and nutritional value. A recent study showed e-beam irradiation to be effective at reducing both,Salmonella,Tennessee and Typhimurium in peanut butter by one log after exposure to less than 1 kGy, highlighting the need to explore this process further. [source] Testing whether samples of blue-green algae have the same cell densityENVIRONMETRICS, Issue 3 2001Geoff M. Laslett Abstract The toxicity of a blue-green algae sample is a function of its cell density, so it is important to know if related samples in a set have different cell densities. Several plausible tests of the null hypothesis of no difference are proposed. Our study assumes that cells are counted in the laboratory using inverse Poisson sampling of blue-green algae colonies, a common Australian technique. In the case of two samples, four standardized difference tests and two likelihood ratio tests are compared on a suite of simulated samples. One of the likelihood ratio tests assumes that colony size has a gamma distribution, but the other makes no explicit assumption. All tests are found to have virtually the same power, but the standardized difference test on the log scale and the likelihood ratio tests have nearly invariant standard null distributions and hence are more convenient to use. The semi-parametric likelihood ratio test generalizes to the multi-sample case very easily. Its performance on three samples is investigated, and found to be satisfactory. Copyright © 2001 John Wiley & Sons, Ltd. [source] Controlling Light Oxidation Flavor in Milk by Blocking Riboflavin Excitation Wavelengths by InterferenceJOURNAL OF FOOD SCIENCE, Issue 9 2009J.B. Webster ABSTRACT:, Milk packaged in glass bottles overwrapped with iridescent films (treatments blocked either a single visible riboflavin [Rb] excitation wavelength or all visible Rb excitation wavelengths; all treatments blocked UV Rb excitation wavelengths) was exposed to fluorescent lighting at 4 °C for up to 21 d and evaluated for light-oxidized flavor. Controls consisted of bottles with no overwrap (light-exposed treatment; represents the light barrier properties of the glass packaging) and bottles overwrapped with aluminum foil (light-protected treatment). A balanced incomplete block multi-sample difference test, using a ranking system and a trained panel, was used for evaluation of light oxidation flavor intensity. Volatiles were evaluated by gas chromatography and Rb degradation was evaluated by fluorescence spectroscopy. Packaging overwraps limited production of light oxidation flavor over time but not to the same degree as the complete light block. Blocking all visible and UV Rb excitation wavelengths reduced light oxidation flavor better than blocking only a single visible excitation wavelength plus all UV excitation wavelengths. Rb degraded over time in all treatments except the light-protected control treatment and only minor differences in the amount of degradation among treatments was observed. Hexanal production was significantly higher in the light-exposed control treatment compared to the light-protected control treatment from day 7; it was only sporadically significantly higher in the 570 nm and 400 nm block treatments. Pentanal, heptanal, and an unidentified volatile compound also increased in concentration over time, but there were no significant differences in concentration among the packaging overwrap treatments for these compounds. [source] Testing whether samples of blue-green algae have the same cell densityENVIRONMETRICS, Issue 3 2001Geoff M. Laslett Abstract The toxicity of a blue-green algae sample is a function of its cell density, so it is important to know if related samples in a set have different cell densities. Several plausible tests of the null hypothesis of no difference are proposed. Our study assumes that cells are counted in the laboratory using inverse Poisson sampling of blue-green algae colonies, a common Australian technique. In the case of two samples, four standardized difference tests and two likelihood ratio tests are compared on a suite of simulated samples. One of the likelihood ratio tests assumes that colony size has a gamma distribution, but the other makes no explicit assumption. All tests are found to have virtually the same power, but the standardized difference test on the log scale and the likelihood ratio tests have nearly invariant standard null distributions and hence are more convenient to use. The semi-parametric likelihood ratio test generalizes to the multi-sample case very easily. Its performance on three samples is investigated, and found to be satisfactory. Copyright © 2001 John Wiley & Sons, Ltd. [source] ASSESSMENT OF PREFERENCE WITH CONTROLS FOR RESPONSE BIAS OPERATING IN THE TEST SITUATION: A PRACTICAL EXAMPLE USING OMEGA-3 ENRICHED WHOLEGRAIN BREADS WITH ECUADORIAN CONSUMERSJOURNAL OF SENSORY STUDIES, Issue 5 2010YAMILLA ALVAREZ-COUREAUX ABSTRACT Ecuadorian consumers performed paired preference tests between sunflower rye bread and artisan wholegrain bread enriched with omega-3 fatty acids. Preferences for each were split fairly evenly. Further difference tests suggested that these preferences were elicited by visual rather than flavor/texture cues. The preference test included a "placebo" pair of "identical" stimuli to assess statistically whether the responses to the two test stimuli were merely because of response biases operating in the test situation and not differences in their sensory attributes. The concept of an "operational preference" was introduced to understand some of the ambiguities involved in the definition of preference. PRACTICAL APPLICATIONS The measurement of preference and acceptance of foods is important for product development and decisions regarding the launching of new products on to the market. The paired preference test has several problems associated with its design and analysis, and these are worthy of investigation. This article uses a practical example to illustrate some procedures developed as solutions to these challenges. Solutions to the problems involved in preference testing are essential so that the food industry can obtain trustworthy data. [source] THE SIGNAL DETECTION THEORY ROC CURVE: SOME APPLICATIONS IN FOOD SENSORY SCIENCEJOURNAL OF SENSORY STUDIES, Issue 2 2008M. O'MAHONY ABSTRACT In psychology, the receiver operating characteristic (ROC) curve is a key part of Signal Detection Theory, which is used for calculating d, values in discrimination tests. In food sensory science, the ROC curve can also be a useful tool. To give a specific example, it is not always convenient to use forced-choice protocols for difference tests; foods may be fatiguing, and assessments with single presentations, like the Yes,No procedure, might be more appropriate. In this case, ROC curves provide a useful method for computing d, values. More generally, ROC curves give information about cognitive strategies. Cognitive strategies are important for difference tests. Values of d, can only be computed if the cognitive strategy used in the test is known. PRACTICAL APPLICATIONS When using methods other than two-alternative forced-choice in difference testing, a receiver operating characteristic (ROC) curve would be required to compute d,. This is because when assessing discrimination ability, the cognitive strategy of the subject must be taken into account, and ROC curves can sometimes reveal the cognitive strategy used by the subject. This article describes how the cognitive strategy can be determined from the subject's ROC curve. The hidden assumptions made when using ROC curves and how these assumptions can be tested are also given. This information is essential to researchers in sensory evaluation as well as those using these methods in a practical setting. [source] Measurement of Angle and Length of the Eustachian Tube on Computed Tomography Using the Multiplanar Reconstruction TechniqueTHE LARYNGOSCOPE, Issue 7 2007Kenji Takasaki MD Abstract Objective: To compare the anatomic features of the eustachian tube (ET) between children with and without otitis media with effusion (OME) and with adults. Methods: The angle and length of the ET in children with OME (54 ears, OME children) and without OME (50 ears, normal children), as well as those of normal adults (90 ears), were measured on computed tomography using the multiplanar reconstruction technique. Results: The angles of ET in the OME children group, the normal children group, and the normal adult group were 20.4 ± 3.5° and 21.2 ± 4.8°, 19.9 ± 3.4° and 20.0 ± 3.6°, and 27.3 ± 2.7° and 27.3 ± 2.8° on the right and the left sides, respectively. There was no significant difference between the right and the left side in any group (P = .541, P = .952, P = .978). The lengths of ET in the OME children group, the normal children group, and the normal adult group were 37.2 ± 3.0 mm (mean ± SD) and 37.6 ± 3.2 mm, 37.5 ± 3.3 mm and 38.0 ± 3.2 mm, and 42.5 ± 2.8 mm and 42.9 ± 2.9 mm on the right and the left sides, respectively. There was no significant difference between the right and left sides in any group (P = .670, P = .597, and P = .545). Both the angles and lengths were significantly greater in the normal adult group than in either the OME children group or the normal children group (one-way analysis of variance and Fisher's protected least significant difference tests, P < .05), but there was no significant difference in either the angle or length of the ET between the OME and normal children groups (P > .05). In the OME and normal children groups, the angle was observed to constantly increase with age, and the values were found to be within the range of the adult size in all the patients older than 7.5 years and 7.7 years in the OME children group and the normal children group, respectively. As well as the angle, the lengths were observed to constantly increase with age, but the increase appeared to be greater at a younger age (until approximately 3 to 4 years) than at an older age, and the values were found to be within the range of the adult size in all the patients older than 6.8 years and 7.7 years in the OME children group and the normal children group, respectively. Conclusion: The angle and length of the ET are more horizontal and shorter in infants than in adults. However, there is no statistical difference between the angle and length of the ET in infants with and without OME. These results lead us to believe that a short and horizontal ET may not be a main etiologic factor related to high susceptibility to OME in infants and children. [source] Effect of quetiapine on cognitive function in schizophrenia: a mismatch negativity potentials studyACTA NEUROPSYCHIATRICA, Issue 1 2009Guo-zhen Yuan Objective:, The purpose of this study was to investigate whether the effects of quetiapine on abnormalities of early auditory processing in patients with schizophrenia were reflected by mismatch negativity (MMN). Methods:, Subjects were 23 patients with schizophrenia and 23 controls. Psychopathology was rated in patients with the Positive and Negative Syndrome Scale (PANSS) at baseline and after 4-week and after 8-week treatments with quetiapine. Auditory stimuli for event-related potentials consisted of 100 ms/1000 Hz standards, intermixed with 100 ms/1500 Hz frequency deviants and 250 ms/ 1000 Hz duration deviants. A stimulus onset asynchrony of each was 300 ms. Electroencephalograph was recorded at Fz. BESA 5.1.8 was used to perform data analysis. MMN waveforms were obtained by subtracting waveforms elicited by standards from those elicited by frequency- or duration-deviant stimuli. Results:, Quetiapine decreased all PANSS scores. Patients showed smaller mean amplitudes of frequency and duration MMN at baseline than did controls. A repeated measure analysis of variance with sessions (i.e. baseline and 4- and 8-week treatments) and MMN type (frequency versus duration) as within-subject factors revealed no significant MMN type or MMN type × session main effect for MMN amplitudes (for MMN type: F = 0.704, df = 1, p = 0.403; for MMN type × session: F = 0.299, df = 2, p = 0.796). Session main effect was significant (F = 3.576, df = 2, p = 0.031). Least square difference tests showed significant differences between MMN amplitudes at 8 weeks and those at both baseline (p = 0.025) and 4 weeks (p = 0.020). MMN amplitudes at 8 weeks were higher than those at baseline. Conclusions:, Quetiapine improved the amplitudes of MMN after the 8-week treatment. MMN offers objective evidence that treatment with the quetiapine may ameliorate preattentive deficits in schizophrenia. [source] Possible role of the adhesin ace and collagen adherence in conveying resistance to disinfectants on Enterococcus faecalisMOLECULAR ORAL MICROBIOLOGY, Issue 6 2008G. Kayaoglu Introduction:, This study aimed to evaluate whether the presence of the ace gene and Ace-mediated binding to collagen confers on Enterococcus faecalis resistance against common endodontic disinfectants. Methods:, Isogenic strains of E. faecalis: OG1RF (wild-type) and TX5256 (ace insertion mutant of OG1RF) were grown in brain,heart infusion broth at 46°C overnight. Standardized bacterial suspensions were pretreated for 1 h either with acid-soluble collagen or acidified phosphate-buffered saline (ac-PBS). Bacteria were challenged with chlorhexidine digluconate (CHX), iodine potassium-iodide (IKI), sodium hypochlorite (NaOCl), and calcium hydroxide [Ca(OH)2]. Samples were removed at 1, 3, and 6 h, and cultured on Todd,Hewitt agar plates. Colonies were counted, the absolute values were log transformed, and the data were statistically analyzed using Fisher's least significant differences test and t -test. Results:, OG1RF was more resistant than TX5256 to IKI, NaOCl, and Ca(OH)2 (P < 0.05). Collagen-exposed OG1RF was more resistant than the ac-PBS-pretreated OG1RF against CHX at 3 h and against IKI at 1 h (P < 0.05); no significant difference was found against NaOCl. As expected, the ace mutant strain, TX5256, pretreated with collagen or ac-PBS did not differ significantly in viability when challenged with CHX, IKI, and NaOCl. An unexpected result was found for Ca(OH)2: collagen-pretreated OG1RF and TX5256 were both more susceptible than ac-PBS-pretreated OG1RF and TX5256, respectively (P < 0.05). Conclusion:, The presence of the ace gene confers resistance against IKI, NaOCl, and Ca(OH)2 on E. faecalis. Exposure to collagen makes the wild-type bacterium more resistant against CHX and IKI; however, exposure to collagen apparently decreases resistance to Ca(OH)2. [source] | |||||||||||||