Assessment of Different Mathematical Models for Calculating and Expressing the Results of Coagulation Test Procedures

1975 ◽  
Vol 34 (02) ◽  
pp. 522-530 ◽  
Author(s):  
J Kahan ◽  
I Norén
Keyword(s):  
Formal Analysis ◽  
Logarithmic Transformation ◽  
Residual Variance ◽  
Coagulation Test ◽  
Clotting Time ◽  
Test Procedures ◽  
Coagulation Activity ◽  
Ratio Approach ◽  
Pronounced Deviation

SummaryCoagulation activity, expressed as percentage of normal and as clotting time ratio, was estimated in 220 specimens from patients on long-term anticoagulant treatment by 3 different coagulation test procedures, i.e. Thrombotest, Simplastin-A and Normotest. The estimates were calculated from the same determinations.The distribution of percentage values showed a fairly pronounced deviation from normality. After logarithmic transformation, the distribution was normalized, the regression lines between Thrombotest and other tests became parallel, and that between PIVKA-insensitive systems was shifted to a 45° line. Logarithmic transformation also stabilized the residual variance. These features make percentage values accessible for treatment according to the standard methods of bioassay statistics.Attempts to normalize the distribution of ratio values by various transformations were unsuccessful. Formal analysis of data revealed a variation in the proportionality of ratio values with the level of estimated coagulation defect. This may restrict the usefulness of the ratio approach. Logarithmic transformation partly reduced the discrepancy.

Use of a Lyophilized Reference Plasma to Compare Coagulation Test Procedures

1975 ◽  
Vol 34 (02) ◽  
pp. 426-444 ◽  
Author(s):  
J Kahan ◽  
I Nohén
Keyword(s):  
Oral Anticoagulant Therapy ◽  
Repeated Measurements ◽  
Test Procedures ◽  
Coagulation Activity ◽  
Close Relationship ◽  
Measured Activity ◽  
Test Materials ◽  
The Difference ◽  
The Stability ◽  
The One

SummaryIn 4 collaborative trials, involving a varying number of hospital laboratories in the Stockholm area, the coagulation activity of different test materials was estimated with the one-stage prothrombin tests routinely used in the laboratories, viz. Normotest, Simplastin-A and Thrombotest. The test materials included different batches of a lyophilized reference plasma, deep-frozen specimens of diluted and undiluted normal plasmas, and fresh and deep-frozen specimens from patients on long-term oral anticoagulant therapy.Although a close relationship was found between different methods, Simplastin-A gave consistently lower values than Normotest, the difference being proportional to the estimated activity. The discrepancy was of about the same magnitude on all the test materials, and was probably due to a divergence between the manufacturers’ procedures used to set “normal percentage activity”, as well as to a varying ratio of measured activity to plasma concentration. The extent of discrepancy may vary with the batch-to-batch variation of thromboplastin reagents.The close agreement between results obtained on different test materials suggests that the investigated reference plasma could be used to calibrate the examined thromboplastin reagents, and to compare the degree of hypocoagulability estimated by the examined PIVKA-insensitive thromboplastin reagents.The assigned coagulation activity of different batches of the reference plasma agreed closely with experimentally obtained values. The stability of supplied batches was satisfactory as judged from the reproducibility of repeated measurements. The variability of test procedures was approximately the same on different test materials.

Mechanical Insertion and Reliability Testing of Thermal Interface Materials for Semiconductor Test and Burn-in Applications

2019 ◽  
Vol 2019 (1) ◽  
pp. 000584-000590
Author(s):  
Dave Saums ◽  
Tim Jensen ◽  
Carol Gowans ◽  
Seth Homer ◽  
Ron Hunadi
Keyword(s):  
Performance Test ◽  
Thermal Interface Materials ◽  
Test Procedures ◽  
Thermal Interface ◽  
Semiconductor Test ◽  
New Material ◽  
And Performance ◽  
And Control ◽  
Interface Materials

Abstract Very challenging requirements exist for thermal interface materials (TIMs) for demanding applications I semiconductor testing. Reliability requirements and multiple contact cycling requirements are substantially different and do not exist in traditional applications for TIMs. Developing new material types to meet these very exacting and unusual requirements has been a long-term goal and requires development of an unusual series of test procedures to demonstrate whether the desired reliability goals have been met. Use of a servo-driven, commercial test stand that has unique features for operation and control is described as the basis for a reliability and performance test program developed for these new materials in three phases, with new data for a fourth test phase added, and comparative values for material performance.

Influence of Early Age Volume Changes on Long-Term Concrete Shrinkage

1998 ◽  
Vol 1610 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Erika E. Holt ◽  
Donald J. Janssen
Keyword(s):  
Concrete Slab ◽  
Drying Shrinkage ◽  
Early Age ◽  
Volume Changes ◽  
Test Procedures ◽  
Cracking Behavior ◽  
Concrete Shrinkage ◽  
Cracking Potential ◽  
Partially Restrained

Volume changes can occur in concrete during the first 24 hr and are generally missed in laboratory shrinkage evaluations. Unfortunately these early age volume changes are present in real pavements and structures and can contribute to the cracking behavior of the concrete at later ages. Early age volume changes can occur in two forms: drying shrinkage before the start of curing and autogenous volume changes. Although these early age volume changes are often dismissed as being insignificant, recent work in Europe has identified magnitudes for early age volume changes of some concretes that are equal to or greater than 28-day drying shrinkage measurements. Expansions have also been identified in some cases. The results of some investigations of volume changes in concrete during the first 24 hr under both drying and nondrying conditions are presented. An example of potential long-term cracking under partially restrained conditions (concrete slab-on-grade modeled by a concrete ring cast around a hollow steel ring) is used to illustrate the magnitude of influence of early age volume changes on concrete cracking. Both test procedures employ nonstandard methods to quantify the cracking potential of concrete.

A New Approach to Fit Bearing Performance to Advanced Gas Engine Technology

2002 ◽  
Author(s):  
Thomas Rumpf ◽  
Johannes Humer ◽  
Elisabeth Schneiderbauer ◽  
Michael Putz
Keyword(s):  
Life Time ◽  
Test Methods ◽  
Hydrodynamic Performance ◽  
Test Procedures ◽  
Gas Engine ◽  
Simulation Tools ◽  
Bearing Materials ◽  
Engine Components ◽  
Long Term Behavior

Gas engines get an increasing market share compared to four stroke engines, especially in the field of energy systems. Under these special firing conditions engine components are stressed differently than in traditional diesel engines. This particularly is the case for bearings. In order to supplement the knowledge base for bearing performance under these aggravated conditions, special test methods have been developed to find out reasons for premature bearing failure characteristics. In combination with experience from the long term behavior of different bearing types in different gas engine applications, this data allows the development of improved bearing materials as well as bearing designs. Using this knowledge in combination with advanced simulation tools, a bearing supplier can offer assistance to select adequate bearing designs, give a life time prediction and in case of unexpected phenomena, redesign recommendations. The paper presents reasons and influences for life time limitations as well as different risk factors for available bearing types and situations. Based on field experience and data from the advanced bearing test procedures, values for bearing performance are given. Data for hydrodynamic performance, tribological properties and emergency running behavior, cavitation resistance, wear resistance and last, but not least corrosion resistance against active sulfur and halogens will be given for traditional and newly developed bearing materials. A short view into the future will finish the presentation.

scholarly journals The changing strength of carbonate silt: parallel penetrometer and foundation tests with cyclic loading and reconsolidation periods

2020 ◽  
Vol 57 (11) ◽  
pp. 1664-1683 ◽  
Author(s):  
Z. Zhou ◽  
D.J. White ◽  
C.D. O’Loughlin
Keyword(s):  
Cyclic Loading ◽  
Soil Strength ◽  
Life Changes ◽  
Test Procedures ◽  
Coefficient Of Consolidation ◽  
Model Foundation ◽  
Order Of Magnitude ◽  
Potential Link ◽  
Surface Foundation

This paper describes a centrifuge study using novel penetrometer tests (T-bar and piezoball) and model foundation tests to explore through-life changes in the strength of a reconstituted natural carbonate silt. The test procedures include episodic cyclic loading, which involves intervals of pore pressure dissipation between cyclic packets. These loads and the associated remoulding and reconsolidation cause significant changes in the soil strength and foundation capacity. Soil strength changes from penetrometer tests differed by a factor of 15 from the fully remoulded strength to a limiting upper value after long-term cyclic loading and reconsolidation. For the model foundation tests, the foundation capacity of a surface foundation and a deep-embedded plate were studied. The soil strength interpreted from the measured foundation capacity varied by a factor of up to three due to episodes of loading and consolidation, with an associated order of magnitude increase in the coefficient of consolidation. The results show a remarkable rise in soil strength over the loading events and provide a potential link between changes in soil strength observed in penetrometer tests and the capacity of foundations, allowing the effects of cyclic loading and consolidation to be predicted.

scholarly journals Comparison of Stress-Hemoconcentration Correction Techniques for Stress-Induced Coagulation

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Anthony W. Austin ◽  
Stephen M. Patterson
Keyword(s):  
Area Under The Curve ◽  
Physiological Saline ◽  
Activated Partial Thromboplastin Time ◽  
Factor Vii ◽  
Clotting Time ◽  
Factor Viii Activity ◽  
Coagulation Activity ◽  
Stress Effects ◽  
Saline Area ◽  
D Dimer

When examining stress effects on coagulation, arithmetic correction is typically used to adjust for concomitant hemoconcentration but may be inappropriate for coagulation activity assays. We examined a new physiologically relevant method of correcting for stress-hemoconcentration. Blood was drawn from healthy men (N=40) during baseline, mental stress, and recovery, and factor VII activity (FVII:C), factor VIII activity (FVIII:C), activated partial thromboplastin time (APTT), prothrombin time (PT%), fibrinogen, D-dimer, and plasma volume were determined. Three hemoconcentration correction techniques were assessed: arithmetic correction and two reconstitution techniques using baseline plasma or physiological saline. Area-under-the-curve (AUC) was computed for each technique. For FVII:C, uncorrected AUC was significantly greater than AUC corrected arithmetically. For PT%, uncorrected AUC was significantly greater than AUC corrected with saline or arithmetically. For APTT, uncorrected AUC was significantly less than AUC corrected with saline and greater than AUC corrected arithmetically. For fibrinogen, uncorrected AUC was significantly greater than AUC corrected with saline or arithmetically. For D-dimer, uncorrected AUC was significantly greater than AUC corrected arithmetically. No differences in AUC were observed for FVIII:C. Saline reconstitution seems most appropriate when adjusting for hemoconcentration effects on clotting time and activity. Stress-hemoconcentration accounted for the majority of coagulation changes.

Comparison of three carbon determination methods on naturally occurring substrates and the implication for the quantification of 'soil carbon'

Soil Research ◽  
2011 ◽  
Vol 49 (1) ◽  
pp. 27 ◽  
Author(s):  
M. K. Conyers ◽  
G. J. Poile ◽  
A. A. Oates ◽  
D. Waters ◽  
K. Y. Chan
Keyword(s):  
Soil Carbon ◽  
Annual Variation ◽  
Organic Substrates ◽  
Test Procedures ◽  
Organic C ◽  
Soil C ◽  
Long Term Trends ◽  
Carbon Determination ◽  
Almost All

Accounting for carbon (C) in soil will require a degree of precision sufficient to permit an assessment of any trend through time. Soil can contain many chemically and physically diverse forms of organic and inorganic carbon, some of which might not meet certain definitions of ‘soil carbon’. In an attempt to assess how measurements of these diverse forms of C might vary with analytical method, we measured the C concentration of 26 substrates by three methods commonly used for soil C (Walkley–Black, Heanes, and Leco). The Heanes and Leco methods were essentially equivalent in their capture of organic C, but the Leco method captured almost all of the inorganic C (carbonates, graphite). The Heanes and Walkley–Black methods did not measure carbonates but did measure 92% and 9%, respectively, of the C in graphite. All three of the common soil test procedures measured some proportion of the charcoal and of the other burnt materials. The proportion of common organic substrates (not the carbonates, graphite, or soil) that was C by weight ranged from ~10% to 90% based on the Heanes and Leco data. The proportion of the organic fraction of those same substrates, as measured by loss-on-ignition, that was C by weight ranged from 42% to 100%. The relationship between Walkley–Black C and total C (by Heanes and Leco) showed that Walkley–Black C was a variable proportion of total C for the 26 substrates. Finally, the well-known, apparent artefact in the Cr-acid methods was investigated: dichromate digestion should contain at least 7–10 mg C in the sample or over-recovery of C might be reported. Our observation that common soil C procedures readily measure C in plant roots and shoots, and in burnt stubble, means that there will likely be intra-annual variation in soil C, because avoidance of these fresh residues is difficult. Such apparent intra-annual variation in soil C will make the detection of long-term trends problematic.

scholarly journals Targeting the Vasculature of Colorectal Carcinoma with a Fused Protein of(RGD)3-tTF

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Zheng-jie Huang ◽  
Yilin Zhao ◽  
Wei-yuan Luo ◽  
Jun You ◽  
Shui-wen Li ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Survival Time ◽  
Tumor Necrosis ◽  
Protein Targeting ◽  
Clotting Time ◽  
Coagulation Activity ◽  
Promising Strategy ◽  
Volume Blood ◽  
Vessel Thrombosis

Purpose. Truncated tissue factor (tTF) fusion protein targeting tumor vasculature can induce tumor vascular thrombosis and necrosis. Here, we generated (RGD)3-tTF in which three arginine-glycine-aspartic (RGD) targeting integrinαvβ3and tTF induce blood coagulation in tumor vessels.Methods. The bioactivities of (RGD)3-tTF including coagulation activity,FXactivation, and binding with integrinαvβ3were performed. The fluorescent labeled (RGD)3-tTF was intravenously injected into tumor-bearing mice and traced in vivo. The tumor growth, volume, blood vessel thrombosis, tumor necrosis, and survival time of mice treated with (RGD)3-tTF were evaluated.Results. The clotting time andFXactivation of (RGD)3-tTF were similar to that of TF (P>0.05) but different with that of RGD (P<0.05). (RGD)3-tTF presented a higher binding withαvβ3than that of RGD and TF at the concentration of 0.2 μmol/L (P<0.05). (RGD)3-tTF could specifically assemble in tumor and be effective in reducing tumor growth by selectively inducing tumor blood vessels thrombosis and tumor necrosis which were absent in mice treated with RGD or TF. The survival time of mice treated with (RGD)3-tTF was higher than that of mice treated with TF or RGD (P<0.05).Conclusion. (RGD)3-tTF may be a promising strategy for the treatment of colorectal cancer.

scholarly journals Calf rennet production and its performance optimization

2018 ◽  
Vol 10 (1) ◽  
pp. 247-252 ◽  
Author(s):  
Asfawosen Mamo ◽  
Nedumaran Balasubramanian
Keyword(s):  
Response Surface ◽  
Performance Optimization ◽  
Raw Materials ◽  
Clotting Time ◽  
Coagulation Activity ◽  
Milk Clotting ◽  
Surface Method ◽  
Cacl2 Concentration ◽  
Milk Coagulation ◽  
Milk Clotting Activity

Milk clotting enzymes are one of the most significant cheese making raw materials impacting and regulating milk coagulation activity. Calf rennet is one of the enzymes which extracted from suckling calf abomasum. The rennet extracted was optimized for its clotting time t (s) by varying three levels of temperature (30, 35 and 40oC), pH (4, 5 and 6) and CaCl2 concentration (0.1, 0.2 and 0.3 gm/500 ml of milk) using response surface method (RSM) and also its milk clotting activity (MCA) was determined. Based on the optimized result, temperature 39.13oC, pH 4 and CaCl2 concentration of 0.21 gm/500ml had resulted minimum clotting time of 91.27 s. Using this minimum clotting time, the strength was found to be 1: 13148, establishing the fact that the calf rennet is the best natural coagulant of milk.

Heparin Resistance, Measured by the Plasma Heparin Thrombin Time, in Patients on Long-term Anticoagulant Therapy with Phenylindanedione Following Coronary Occlusion

1960 ◽  
Vol 04 (02) ◽  
pp. 261-268
Author(s):  
T Holger-Madsen ◽  
M Schioler
Keyword(s):  
Comparative Study ◽  
Anticoagulant Therapy ◽  
Coronary Occlusion ◽  
Tolerance Test ◽  
Thrombin Time ◽  
Clotting Time ◽  
Heparin Resistance ◽  
History Of ◽  
Plasma Heparin

SummaryOf 74 patients with a history of coronary occlusion 42 received anticoagulant (phenylindanedione) therapy, while 32 were untreated. Both groups were investigated in a comparative study of prothrombin determination, heparin tolerance test, and plasma heparin thrombin time. By the latter method the clotting time with thrombin is determined on heparinized, platelet-poor citrated plasma. In several patients on anticoagulant therapy whose prothrombin-proconvertin level was well adjusted and whose heparin clotting time, as measured by the heparin tolerance test, was definitely prolonged in relation to normal, an increased heparin resistance might still be demonstrated in the form of a distinct shortening of the heparin thrombin time. In the majority of the treated patients the anticoagulant therapy had entailed a prolongation of the heparin clotting time as measured by the heparin tolerance test. As measured by the heparin thrombin time, however, the treatment was found to have had no influence on the heparin resistance, there being no difference between the frequency of shortened heparin thrombin time in the treated and in the untreated group.

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