Indirect Test Method Research Articles

Research of Self Pre-Stress Test of Concrete-Filled Steel Tube Arch Rib

Indirect test method of installing vibrating wire strain gauges as sensors in outer surface of steel tube rib is adopted to carry out the research of concrete-filled steel tube (CFST) self pre-stress test for a half-through CFST arch bridge with a main span of 240m. The results show that indirect test method is a practical approach for self pre-stress test, and the measured value of self pre-stress from this method is much smaller than that of being theoretically calculated by concrete free expansion ratio.

Diagnostic efficacy of indirect hemagglutination test inrelation to Kato method for diagnosis of <i>Schistosomiasis mansoni</i>

BACKGROUND: Sensitive and specific diagnostic tools are very central to decide on individual case management and at all stages of control programs in schistosomiasis. This study was undertaken to assess the diagnostic efficacy of a commercial indirect hemagglutination test in detection of schistosomiasis mansoni in relation to the Kato method. METHODS: In a cross sectional study undertaken in May 2004, blood and stool samples were collected from 134 children in Bochesa Elementary School around Ziway town. The stool specimens were processed using Kato method and examined microscopically. Eggs per gram of stool were computed as geometric mean. Sera were separated and transported to laboratory. Indirect hemagglutination test was performed following procedures given by the manufacturers. The diagnostic performance of indirect hemagglutination was evaluated using Kato as the gold standard. RESULTS: The overall prevalence of intestinal schistosomiasis as detected by indirect hemagglutination test and Kato method was 74.6% and % 76.1%, respectively (p = 0.284). The respective prevalence of infection as detected by indirect hemagglutination tests and Kato method among male students was 82.6% and 85.0 % where as the corresponding value for females was 60.4% for both indirect hemagglutination test and Kato method. The sensitivity and specificity of the indirect hemagglutination test were 83% and 53%, the positive predictive value being 85%. However, there was discrepancy between indirect hemagglutination test and Kato method in determining the intensity of infection. Only 5% of the examined individuals had light infection with a cut off titer of 81: 256 as detected by IHA test while 95% of the cases had heavy infection with a cut off titer of ; 1: 512. On the other hand, the Kato method revealed that 18.5% of the children was heavily infected (;400 epg) while 81.5 % of them had light to moderate infection (8399 epg). CONCLUSIONS: The present findings indicate that indirect hemagglutination test can be used as an adjunct to the Kato method for field use in the diagnosis of intestinal chistosomiasis. Nevertheless, the fact that the test is expensive and also not a rapid test may limit its use in the field for epidemiological application.

Scale effects in metal-forming friction and lubrication

Downscaling of metal-forming operations from macro- to microscale implies significant changes caused by size effects. Among these, the friction increases as reported by researchers using indirect test methods such as the ring-compression test and double-cup-extrusion test. In this study, a new test equipment is developed for studies of the size effect in metal-forming friction in the range from macro- to microscale. Investigations confirm a significant friction increase when downscaling. Visual inspection of the workpieces shows this to be explained by the amount of open and closed lubricant pockets.

Unexpected suppression of anti‐Fya and prevention of hemolytic disease of the fetus and newborn after administration of Rh immune globulin

Rh immune globulin (RhIG) has been used successfully for many years for the antenatal suppression of anti-D in D- mothers carrying D+ babies to prevent hemolytic disease of the fetus and newborn. Although the mechanism of RhIG-induced immunosuppression remains unknown, a recent report (TRANSFUSION 2006;46:1316-22) has shown that women receiving RhIG produce elevated levels of transforming growth factor (TGF)β-1, a powerful immunosuppressant cytokine. It was suggested that induction of TGFβ-1 and immunosuppression may be independent of cognate antigen recognition by RhIG. Herein, we present a description of a mother and baby that supports this hypothesis. Red blood cells and serum were analyzed using saline-tube indirect antiglobulin test methods. RhIG (RhoGAM) was administered after each amniocentesis performed at 28, 31, and 36 weeks' gestation. A group A, D-(cde), K+, Fy(a-b+), MNs, Jk(a+b+) mother with no detectable anti-D had an anti-Fy(a) titer of 4096 before RhIG but only 256 after RhIG. Mother gave birth to a group O, D-(cde), Fy(a+b+) healthy baby boy having a weak-positive direct antiglobulin test with anti-Fy(a) eluted from his cells and the titer in the cord serum was 4. This case demonstrates the potential immunosuppressive properties of RhIG for down regulation of a possible clinically significant alloantibody, not anti-D, where no D+ antigen is in the circulation of the mother. The case illustrates the potential utility for using RhIG to modulate antibody levels in situations other than for classical suppression of anti-D production. Although the mechanism in this case is unknown, TGFβ-1-mediated or antibody-mediated immunosuppression to soluble nonparticulate antigens are possible mechanisms.

Permeability and swelling characteristics of bentonite

Permeability and swelling characteristics of bentonite and bentonite-sand are the essential parameters for designing any type of waste disposal or in geo-environmental engineering applications. To design and construct these facilities accurate values of permeability for these bentonite-sand mixtures must be evaluated. For this purpose, a series of various laboratory tests were performed to investigate the coefficient of permeability using direct and indirect test methods derived from consolidation theory using liquid limit 1.5 of bentonite. Permeability tests were also carried out for dynamically compacted bentonite. Void ratio of bentonite is a key parameter of permeability for bentonite and bentonite-sand mixtures. The specimen manufacture method had no effect on permeability. A series of swelling pressure and deformation tests are performed using variable content (30 to 90%) of bentonite at initial dry density of 2 g/cm3to investigate the characteristics of buffer material for radioactive waste disposal. Content of bentonite in bentonite-sand mixture is the prime criteria of buffer material and must be taken into consideration in designing any types of waste disposal facilities. Content of bentonite and loading pressure on the specimens is noticeably influenced on maximum swelling rate. Key words: Bentonite, permeability, swelling pressure, swelling deformation.

A discussion of paper “A novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials” by G. Zi, H. Oh, S.K. Park

A discussion of paper “A novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials” by G. Zi, H. Oh, S.K. Park

Frost resistance of clay roofing tiles: Case study

In order to give required protection of the buildings, clay roofing tiles should be resistant to freezing conditions. In the present study, clay roofing tiles were fired at different temperatures. Afterwards, direct and indirect test methods were used to evaluate their frost resistance. The direct method in standard EN 539-2 was applied, ASTM C 1167-03 was used for indirect methods, and Maage factor was calculated from Hg-porosimetry curve. It was confirmed that the temperature of firing is the main influential parameter as it affects the porosity of a ceramic body. The comparison between indirect and direct methods of prediction and test of frost resistance has also shown good correlation.

Is There a Sex Ratio Difference in the Familial Aggregation of Specific Language Impairment? A Meta-Analysis

Specific language impairment (SLI) is known to aggregate in families. Debate exists on whether the male sex presents an additional risk for SLI. This meta-analysis examined whether there is a sex ratio difference in the risk for impairment among family members of an SLI proband and whether this is mediated by assessment method (direct assessment via psychometric tests vs. indirect assessment via questionnaire/interview) or relative type (sibling vs. parent). Twelve studies met inclusion criteria, including 11 parent and 9 sibling samples. Risk ratios, indicating relative risk for language difficulties for males versus females, were calculated as a function of assessment method and relative type. Direct assessments identified a male predominance of language impairment, with a pooled risk ratio of 1.73 for siblings (95% confidence interval [CI]: 1.20-2.52) and 1.54 for parents (95% CI: 1.14-2.07). No sex differences were observed for studies using indirect testing methods, with mean risk ratios of 1.12 (0.85-1.48) and 1.17 (0.92-1.49) for sibling and parent samples, respectively. A predominance of affected males among family members is observed when using direct assessments only. This finding is interpreted with reference to the strengths and weaknesses of different assessment methodologies and what sex differences may indicate about the biological mechanisms underlying the SLI phenotype.

Quantification of dynamic tensile parameters of rocks using a modified Kolsky tension bar apparatus

For brittle materials, the tensile strength plays an important role in mechanical analyses and engineering applications. Although quasi-static direct and dynamic indirect tensile strength testing methods have already been developed for rocks, the dynamic direct pull test is still necessary to accurately determine the tensile strength of rocks. In this paper, a Kolsky tension bar system is developed for measuring the dynamic direct tensile strength of rocks. A dumbbell-shaped sample is adopted and attached to the bars using epoxy glue. The pulse shaping technique is utilized to eliminate the inertial effect of samples during test. The single pulse loading technique is developed for the effective microstructure analyses of tested samples. Two absorption devices are successfully utilized to reduce the reflection of waves in the incident bar and transmitted bar, respectively. Laurentian granite (LG) is tested to demonstrate the feasibility of the proposed method. The tensile strength of LG increases with the loading rate. Furthermore, the nominal surface energy of LG is measured, which also increases with the loading rate.

Direct susceptibility testing for multi drug resistant tuberculosis: A meta-analysis

BackgroundOne of the challenges facing the tuberculosis (TB) control programmes in resource-limited settings is lack of rapid techniques for detection of drug resistant TB, particularly multi drug resistant tuberculosis (MDR TB). Results obtained with the conventional indirect susceptibility testing methods come too late to influence a timely decision on patient management. More rapid tests directly applied on sputum samples are needed. This study compared the sensitivity, specificity and time to results of four direct drug susceptibility testing tests with the conventional indirect testing for detection of resistance to rifampicin and isoniazid in M. tuberculosis. The four direct tests included two in-house phenotypic assays – Nitrate Reductase Assay (NRA) and Microscopic Observation Drug Susceptibility (MODS), and two commercially available tests – Genotype® MTBDR and Genotype® MTBDRplus (Hain Life Sciences, Nehren, Germany).MethodsA literature review and meta-analysis of study reports was performed. The Meta-Disc software was used to analyse the reports and tests for sensitivity, specificity, and area under the summary receiver operating characteristic (sROC) curves. Heterogeneity in accuracy estimates was tested with the Spearman correlation coefficient and Chi-square.ResultsEighteen direct DST reports were analysed: NRA – 4, MODS- 6, Genotype MTBDR® – 3 and Genotype® MTBDRplus – 5. The pooled sensitivity and specificity for detection of resistance to rifampicin were 99% and 100% with NRA, 96% and 96% with MODS, 99% and 98% with Genotype® MTBDR, and 99% and 99% with the new Genotype® MTBDRplus, respectively. For isoniazid it was 94% and 100% for NRA, 92% and 96% for MODS, 71% and 100% for Genotype® MTBDR, and 96% and 100% with the Genotype® MTBDRplus, respectively. The area under the summary receiver operating characteristic (sROC) curves was in ranges of 0.98 to 1.00 for all the four tests. Molecular tests were completed in 1 – 2 days and also the phenotypic assays were much more rapid than conventional testing.ConclusionDirect testing of rifampicin and isoniazid resistance in M. tuberculosis was found to be highly sensitive and specific, and allows prompt detection of MDR TB.

Semicircular bend testing with split Hopkinson pressure bar for measuring dynamic tensile strength of brittle solids

We propose and validate an indirect tensile testing method to measure the dynamic tensile strength of rocks and other brittle solids: semicircular bend (SCB) testing with a modified split Hopkinson pressure bar (SHPB) system. A strain gauge is mounted near the failure spot on the specimen to determine the rupture time. The momentum trap technique is utilized to ensure single pulse loading for postmortem examination. Tests without and with pulse shaping are conducted on rock specimens. The evolution of tensile stress at the failure spot is determined via dynamic and quasistatic finite element analyses with the dynamic loads measured from SHPB as inputs. Given properly shaped incident pulse, far-field dynamic force balance is achieved and the peak of the loading matches in time with the rupture onset of the specimen. In addition, the dynamic tensile stress history at the failure spot obtained from the full dynamic finite element analysis agrees with the quasistatic analysis. The opposite occurs for the test without pulse shaping. These results demonstrate that when the far-field dynamic force balance is satisfied, the inertial effects associated with stress wave loading are minimized and thus one can apply the simple quasistatic analysis to obtain the tensile strength in the SCB-SHPB testing. This method provides a useful and cost effective way to measure indirectly the dynamic tensile strength of rocks and other brittle materials.

The biocompatibility of modified experimental Portland cements with potential for use in dentistry

To evaluate the biocompatibility of a group of new potential dental materials and their eluants by assessing cell viability. Calcium sulpho-aluminate cement (CSA), calcium fluoro-aluminate cement (CFA) and glass-ionomer cement (GIC; Ketac Molar), used as the control, were tested for biocompatibility. Using a direct test method cell viability was measured quantitatively using alamarBluetrade mark dye, and an indirect test method where cells were grown on material elutions and cell viability was assessed using methyltetrazolium (MTT) assay as recommended by ISO 10 993-Part 5 for in vitro testing. Statistical analysis was performed by analysis of variance and Tukey multi-comparison test method. Elution collected from the prototype cements and the GIC cured for 1 and 7 days allowed high cell activity after 24 h cell exposure, which reduced after 48 h when compared to the nontoxic glass-ionomer control, but increased significantly after 72 h cell contact. Elutions collected after 28 days revealed reduced cell activity at all cell exposure times. Cells placed in direct contact with the prototype materials showed reduced cell activity when compared with the control. Cell growth was poor when seeded in direct contact with the prototype cements. GIC encouraged cell growth after 1 day of contact. The eluted species for all the cements tested exhibited adequate cell viability in the early ages with reduced cell activity at 28 days. Changes in the production of calcium hydroxide as a by-product of cement hydration affect the material biocompatibility adversely.

A novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials

A novel indirect tensile test method, the biaxial flexure test (BFT) method, has been developed to measure the biaxial tensile strength of concretes. The classical modulus of rupture (MOR) test has been generalized to three dimensions. In this method, we use a circular plate as the new test specimen. This plate is supported by an annular ring. We apply an external load to this specimen through a circular edge. The centers of the specimen, the loading device and the support are identical. The biaxial tensile strength measured by this new method is about 19% greater than the uniaxial tensile strength obtained from the classical modulus of rupture test as reported by other researchers. However, at the same time, we also found that the stochastic deviation of the biaxial tensile strength is about 63% greater than the uniaxial strength.

Determination of mechanical properties of rocks using simple methods

Statistical equations have been determined for estimating the mechanical properties of rocks using non-destructive and indirect test methods. Nineteen different rock types were tested to obtain the relationships between Shore hardness, point load index, sound velocity, Schmidt hardness and porosity and uniaxial compressive strength, indirect tensile strength and abrasion resistance. Results of regression analyses showed satisfactory correlations.

A framework for evaluating usability of clinical monitoring technology

Technology design is a complex task, and acceptability is enhanced when usability is central to its design. Evaluating usability is a challenge for purchasers and developers of technology. We have developed a framework for testing the usability of clinical monitoring technology through literature review and experience designing clinical monitors. The framework can help designers meet key international usability norms. The framework includes these direct testing methods: thinking aloud, question asking, co-discovery, performance and psychophysiological measurement. Indirect testing methods include: questionnaires and interviews, observation and ethnographic studies, and self-reporting logs. Inspection, a third usability testing method, is also included. The use of these methods is described and practical examples of how they would be used in the development of an innovative monitor are given throughout. This framework is built on a range of methods to ensure harmony between users and new clinical monitoring technology, and have been selected to be practical to use.

1.266 Comparison of the Extensor-digitorum-brevis test (EDB) vs mouse diaphragm assay (MDA) as indirect test methods for detection of Botulinum-toxin A (BTXA) antibodies

1.266 Comparison of the Extensor-digitorum-brevis test (EDB) vs mouse diaphragm assay (MDA) as indirect test methods for detection of Botulinum-toxin A (BTXA) antibodies

Optimal prewarming conditions for Rh antibody testing

Although prewarming (PW) can reduce the confounding agglutination of cold-reactive antibodies when testing for warm-reactive antibodies, PW also can adversely affect the detection of warm-reactive antibodies. This study was conducted to determine PW conditions that optimized Rh antibody detection. In 38 plasma samples with Rh system antibodies detected by any of four methods, and in 8 other samples with cold-reactive antibodies, reactivity was assessed by titer and score. PW to 37 degrees C often reduced reaction scores by all methods especially the low-ionic-strength saline indirect antiglobulin test and bromelin methods. In analyses warming red blood cell (RBC) suspensions or plasma, the reaction scores were decreased only when the RBC suspension was warmed, suggesting that RBC PW decreased Rh antibody reactivity. The warming period ranging from 5 to 30 minutes all decreased Rh system reaction scores, an effect persisting up to 120 minutes. At lower temperatures (27, 30, and 33 degrees C), numbers of samples showing decreased reaction score for Rh system antibodies decreased in a temperature-dependent manner. Testing at 27 degrees C also permitted some agglutination involving cold-reactive antibodies, whereas higher temperatures successfully suppressed their agglutination. PW at 30 degrees C minimizes problems in accurately detecting Rh system antibodies.

A study on the coherence of compacted binary composites of microcrystalline cellulose and paracetamol

This paper describes and interprets the coherence and the tensile strength of bi-component compacted tablets, composing a mixture of a poorly compactable drug, paracetamol and a very cohesive and ductile carrier, microcrystalline cellulose (MCC), Avicel ® PH 102, using the concepts of the stored elastic strain in conjunction with the particle size and the relative volume fraction of the powders. Cylindrical compacts of the bi-component tablets, at various compositions formed at a common ultimate stress of 99 MPa, were subsequently fractured using the indirect tensile test method (Brazilian test method) to obtain a measure of their tensile strength. Various inter-relations between the compaction and tensile rupture characteristics are described. A simple model, which may predict the required volume fraction of MCC to produce a cohesively viable tablet is suggested, and applied to the current system. The results show to some extent the consistency of the suggested model with the experimental results.

The chemical constitution and biocompatibility of accelerated Portland cement for endodontic use

To evaluate the biocompatibility of mineral trioxide aggregate and accelerated Portland cement and their eluants by assessing cell metabolic function and proliferation. The chemical constitution of grey and white Portland cement, grey and white mineral trioxide aggregate (MTA) and accelerated Portland cement produced by excluding gypsum from the manufacturing process (Aalborg White) was determined using both energy dispersive analysis with X-ray and X-ray diffraction analysis. Biocompatibility of the materials was assessed using a direct test method where cell proliferation was measured quantitatively using Alamar Blue dye and an indirect test method where cells were grown on material elutions and cell proliferation was assessed using methyltetrazolium assay as recommended by the International standard guidelines, ISO 10993-Part 5 for in vitro testing. The chemical constitution of all the materials tested was similar. Indirect studies of the eluants showed an increase in cell activity after 24 h compared with the control in culture medium (P<0.05). Direct cell contact with the cements resulted in a fall in cell viability for all time points studied (P<0.001). Biocompatibility testing of the cement eluants showed the presence of no toxic leachables from the grey or white MTA, and that the addition of bismuth oxide to the accelerated Portland cement did not interfere with biocompatibility. The new accelerated Portland cement showed similar results. Cell growth was poor when seeded in direct contact with the test cements. However, the elution made up of calcium hydroxide produced during the hydration reaction was shown to induce cell proliferation.

Use of Brucella canis antigen for detection of ovine serum antibodies against Brucella ovis

Brucella ovis causes a genital disease of sheep manifested by epididymitis in rams and placentitis in ewes producing reduced fertility in the flock. Clinical diagnosis is not sensitive enough and bacteriological testing is not feasible for detection of the disease in large numbers of animals. Indirect methods of serological testing are preferred for routine diagnosis, of which agar gel immunodiffusion (AGID), complement fixation (CF) and ELISA tests are recommended as the most efficient. Since B. ovis shares antigenic components with Brucella canis, it would seem that either strain could be used as antigen with the same results; however, the advantage of the B. canis (M−) strain variant is that it can be used to develop a satisfactory antigen for agglutination tests. We present data on AGID and IELISA tests using B. ovis antigen and rapid screening agglutination test (RSAT), 2-mercapto-ethanol RSAT (2ME-RSAT) and IELISA using B. canis antigen. We tested 225 animals. The cut-off values were adjusted by ROC analysis using 51 negative and 32 positive sera; the IELISA- B. canis cut-off value was 39 (% P) and IELISA- B. ovis, 51 (% P), with 100% sensitivity and specificity. Of the 32 positive sera from the infected flock RSAT detected 32 (100%), 2ME-RSAT 29 (91%) and AGID 31 (97%). Of the 142 sera from suspicious flocks, 46 were negative and 56 positive in all the tests; 16 were positive by RSAT, IELISA- B. canis and IELISA- B. ovis, 20 positive only with RSAT and 2 positive only by both IELISAs. RSAT is a very sensitive screening test that, because of its simplicity and easy interpretation, following a study in larger sample, could replace AGID as a screening test for diagnosis of ovine brucellosis caused by B. ovis. The IELISA- B. canis or IELISA- B. ovis could be used as confirmatory tests, since they show equal specificity and sensitivity.