scholarly journals ESTIMATING MARINE RESERVOIR EFFECTS IN ARCHAEOLOGICAL CHRONOLOGIES: COMPARING ΔR CALCULATIONS IN PRINCE RUPERT HARBOUR, BRITISH COLUMBIA, CANADA

2018 ◽  
Vol 83 (4) ◽  
pp. 659-680 ◽  
Author(s):  
Andrew Martindale ◽  
Gordon T. Cook ◽  
Iain McKechnie ◽  
Kevan Edinborough ◽  
Ian Hutchinson ◽  
...  
Keyword(s):  
British Columbia ◽  
Calibration Curve ◽  
Sample Selection ◽  
Large Set ◽  
Variable Expression ◽  
Archaeological Practice ◽  
Accuracy And Precision ◽  
Prince Rupert Harbour ◽  
Archaeological Chronologies ◽  
Age Estimates

The best method for quantifying the marine reservoir effect (MRE) using the global IntCal Marine13 calibration curve remains unresolved. Archaeologists frequently quantify uncertainty on MRE values as errors computed from single pairs of marine-terrestrial radiocarbon ages, which we argue significantly overstates their accuracy and precision. Here, we review the assumptions, methods, and applications of estimating MRE via an estimate of the additional regional offset between the marine and terrestrial calibration curves (ΔR) for the Prince Rupert Harbour (PRH) region of British Columbia, Canada. We acknowledge the influence on ΔR of MRE variation as (1) a dynamic oceanographic process, (2) its variable expression in biochemical and geochemical pathways, and (3) compounding errors in sample selection, measurement, and calculation. We examine a large set of marine-terrestrial pairs (n= 63) from PRH to compare a common archaeological practice of estimating uncertainty from means that generate an uncertainty value of ±49 years with a revised, more appropriate estimate of error of ± 230 years. However, we argue that the use of multiple-pair samples estimates the PRH ΔR as 273 ± 38 years for the last 5,000 years. Calculations of error that do not consider these issues may generate inaccurate age estimates with unjustifiable precision.

scholarly journals Validation of an LC-MS/MS Method for the Quantification of Caffeine and Theobromine Using Non-Matched Matrix Calibration Curve

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2863 ◽  
Author(s):  
Vera M. Mendes ◽  
Margarida Coelho ◽  
Angelo R. Tomé ◽  
Rodrigo A. Cunha ◽  
Bruno Manadas
Keyword(s):  
Human Plasma ◽  
Calibration Curve ◽  
Considerable Effort ◽  
Caffeine Consumption ◽  
Internal Standards ◽  
Beneficial Effects ◽  
Calibration Curves ◽  
Accuracy And Precision ◽  
Precise Quantification ◽  
Surrogate Matrix

Caffeine is one of the most widely consumed psycho-stimulants. The study of the beneficial effects of caffeine consumption to decrease the risk of developing several neuropsychiatric pathologies is receiving increasing attention. Thus, accurate and sensitive methods have been developed, mainly by LC-MS/MS, in order to quantify caffeine and its metabolites. These quantifications of caffeine and its metabolites by LC-MS/MS require a considerable effort to select or find a surrogate matrix, without the compounds of interest, to be used in the calibration curves. Thus, we evaluated the possibility of using calibration curves prepared in solvent instead of calibration curves prepared in human plasma. Results show that the calibration curves prepared in solvent and in human plasma were similar by comparing their slopes and interceptions, and the accuracy and precision were within the limits of acceptance for both calibration curves. This work demonstrates that, by using internal standards, it is possible to use a calibration curve in solvent instead of a calibration curve in plasma to perform an accurate and precise quantification of caffeine and theobromine.

In-house Calibration of the International Sensitivity Index or Calibration Curve for Determination of the International Normalized Ratio

2004 ◽  
Vol 128 (3) ◽  
pp. 308-312
Author(s):  
William F. Brien ◽  
Linda Crawford ◽  
Anne Raby ◽  
Harold Richardson
Keyword(s):  
Calibration Curve ◽  
Oral Anticoagulants ◽  
International Normalized Ratio ◽  
Sensitivity Index ◽  
Improve Performance ◽  
Accuracy And Precision ◽  
The Stability ◽  
Method Of Assessment ◽  
International Sensitivity Index

Abstract Context.—The international normalized ratio (INR) has been used since 1983 to standardize prothrombin time results for patients on oral anticoagulants. However, significant interlaboratory variations have been noted. Attempts have been made to address these differences with the use of instrument-specific International Sensitivity Index (ISI) values and in-house calibration of ISI values. Objective.—To assess the performance of laboratories using a calibration curve for INR testing. Design.—Attempts to improve performance of the INR include the use of instrument-specific ISI values, model-specific ISI values, in-house calibration of ISI values, and more recently, the preparation of a calibration curve. Several studies have shown an improvement in performance using these procedures. In this study of licensed laboratories performing routine coagulation testing in the Province of Ontario, Canada, the determination of the INR by a calibration curve was compared with the laboratories' usual method of assessment. These methods were subsequently analyzed by comparing the results to instrument-specific ISI, model-specific ISI, and in-house calibrators. International normalized ratios derived by both methods were analyzed for accuracy and precision. The stability of a calibration curve was also investigated. Results.—Performance of INR testing has improved with use of a calibration curve or in-house calibrators. Conclusion.—The results confirm that either in-house calibrators or the calibration curve improve performance of INR testing. The calibration curve may be easier to use and appears stable up to 4 months.

scholarly journals CALCINED BONE AS A RELIABLE MEDIUM FOR RADIOCARBON DATING: A TEST USING PAIRED NORTH AMERICAN SAMPLES

2017 ◽  
Vol 82 (3) ◽  
pp. 593-608 ◽  
Author(s):  
James C. Chatters ◽  
James W. Brown ◽  
Steven Hackenberger ◽  
Patrick McCutcheon ◽  
Jonathan Adler
Keyword(s):  
British Columbia ◽  
Pacific Northwest ◽  
Radiocarbon Dating ◽  
Bone Collagen ◽  
Organic Media ◽  
Radiocarbon Age ◽  
Cross Dating ◽  
Chronometric Analysis ◽  
Calcined Bone ◽  
Age Estimates

Radiocarbon dating using charcoal and bone collagen, two standards of archaeological chronology, can be difficult to impossible in environments where natural burning is common and bone does not preserve well. In such settings, charcoal ages cannot always be trusted and collagen is unavailable. Calcined bone can be a viable alternative medium in these situations but it has rarely been exploited in the Americas. One area that could benefit from its use is the forested Pacific Northwest. We compare calcined bone ages with charcoal and/or collagen dates from individual features or discrete cultural strata in 10 Washington, Oregon, Idaho, and British Columbia sites dating between 9000 and 100 B.P. Resulting radiocarbon age estimates based on calcined bone closely match those based on charcoal and/or collagen in nearly all cases. We obtained calcined bone dates from three additional Holocene-aged sites that had not previously produced accurate results, obtaining findings consistent with estimates based on cross dating. Preserving well where all other organic media of cultural origin are lost or unreliable, calcined bone holds promise for dating sites in conifer forests and other acidic soil settings, and can allow researchers to refine archaeological sequences that have long defied accurate chronometric analysis.

scholarly journals Formal Statistical Models for Estimating Radiocarbon Calibration Curves

Radiocarbon ◽  
2004 ◽  
Vol 46 (3) ◽  
pp. 1093-1102 ◽  
Author(s):  
C E Buck ◽  
P G Blackwell
Keyword(s):  
Calibration Curve ◽  
Statistical Models ◽  
Random Effect ◽  
Modeling Framework ◽  
Sources Of Uncertainty ◽  
Calibration Curves ◽  
Dating Methods ◽  
Diverse Data ◽  
Radiocarbon Calibration ◽  
Age Estimates

We report on the development and implementation of a model-based statistical method for the estimation of radiocarbon calibration curves using diverse data. The method takes account of uncertainty on both the 14C and calendar scales, coherently integrating data, the calendar age estimates of which arise from different dating methods. It also allows for correlation between observations, if they have particular sources of uncertainty in common. We adopt an approach based on a random walk model, tailoring it to take account of possible calendar age offsets between different data sources by adding a random effect component. The latter allows us to use the same modeling framework for constructing the new calibration curve IntCal04, the comparison curve NotCal04, the Southern Hemisphere curve SHCal04, and the marine calibration curve Marine04.

Determination of Sucralose by Controlled UV Photodegradation Followed by UV Spectrophotometry

2013 ◽  
Vol 96 (3) ◽  
pp. 603-606
Author(s):  
Mohd Idris ◽  
V Jayathirtha Rao ◽  
Deepak Middha ◽  
Sudhir Kumar Shukla ◽  
Tulsidas Ramachandra Rao Baggi
Keyword(s):  
Correlation Coefficient ◽  
Alkaline Medium ◽  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Artificial Sweeteners ◽  
Uv Spectrophotometry ◽  
Medium Ph ◽  
Accuracy And Precision ◽  
Uv Photodegradation

Abstract A simple and time-efficient UV spectrophotometric method was developed for the determination of sucralose in artificial sweeteners. The procedure is based on the UV spectrophotometric determination of the photodegraded product at 270 nm in alkaline medium (pH 12). LOD for this method was 0.02 g/L, and the calibration curve was found to obey Beer's law in the concentration range of 0.1 to 1.2 g/L, with a correlation coefficient (R2) value of 0.9977. The proposed method was studied for accuracy and precision.

scholarly journals New Spectrophotometric Method for Estimation of Ceftazidime in pure and pharmaceutical dosage

2019 ◽  
Vol 30 (3) ◽  
pp. 47
Author(s):  
Nibras Sabah Mohammed ◽  
Mohammed Jasim M. Hassan ◽  
Amer Saleh Mahdi
Keyword(s):  
Spectrophotometric Method ◽  
Calibration Curve ◽  
Coupling Reaction ◽  
Molar Absorptivity ◽  
Local Market ◽  
Optimal Conditions ◽  
Limit Of Quantification ◽  
Commercial Preparation ◽  
Accuracy And Precision ◽  
Colored Compound

A new simple, rapid, inexpensive and nontoxic spectrophotometric method for thedetermination of Ceftazidime in the pure and local market formulation was proposed. Themethod is based on the coupling reaction between the diazotized drug and 4-tert-butylphenol(4-TBP) to produce a colored compound with a (λ max 500 nm). The optimal conditions for thefactors affecting the formation of this compound were studied. Beer's law was obeyed and alinear calibration curve was obtained over the range of (1–10 μg/mL) with a correlationcoefficient (r=0.9890), molar absorptivity (ε=6.62710 3 L/mol.cm), the limit of detection0.314 μg/mL, and the limit of quantification LOQ 1.047 μg/mL. the accuracy and precision ofthe method were checked and the method was applied successfully for the determination ofCeftazidime in commercial preparation and the values of recovery percent and RSD% rangedbetween (93.11 - 102.20%) and (0.48 - 9.54%) respectively.

MLD Method for the Determination of Major Components in MgO-Cr Refractory Products

2016 ◽  
Vol 680 ◽  
pp. 76-81
Author(s):  
Juan Juan Lu ◽  
Yu Bing Liu ◽  
Jian Xing Ren ◽  
Wei Han
Keyword(s):  
Refractory Material ◽  
Calibration Curve ◽  
High Sensitivity ◽  
Technical Difficulty ◽  
Detection Sensitivity ◽  
Dilution Ratio ◽  
Novel Approach ◽  
Accuracy And Precision ◽  
Main Components

In this paper a novel approach is presented for determination of the main components in MgO-Cr refractory material. With the approach, the intensity conversion of fused sample at different dilution ratios can be obtained by establishing the correlation between elements’ intensity and dilution ratio. MgO-Cr refractory material is fused hardly and the dilution ratio requires more than 20 in XRF analysis. Nevertheless, high dilution can reduce the detection sensitivity of low content elements. Using the technology of intensity conversion at different dilution ratio in this paper, a calibration curve was obtained with different dilution ratios. In this method, we obtained a calibration curve successfully and got the satisfactory results for MgO-Cr refractory which was fused well. The new method suggests consistent accuracy and precision with standard method, and it can also simplify the preparation process of samples. The approach shows high sensitivity, good accuracy and precision, meanwhile, it reduces the technical difficulty and labor intensity greatly in analysis method.

scholarly journals Immuno-genomic classification of colorectal cancer organoids reveals cancer cells with intrinsic immunogenic properties associated with patient survival

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Eun Jeong Cho ◽  
Minsuh Kim ◽  
Daum Jo ◽  
Jihye Kim ◽  
Ji-Hye Oh ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cancer Cells ◽  
Signaling Pathways ◽  
Patient Survival ◽  
Expression Profiles ◽  
Disease Stage ◽  
Large Set ◽  
Primary Tumors ◽  
Variable Expression ◽  
Immunogenic Properties

Abstract Background The intrinsic immuno-ge7nomic characteristics of colorectal cancer cells that affect tumor biology and shape the tumor immune microenvironment (TIM) are unclear. Methods We developed a patient-derived colorectal cancer organoid (CCO) model and performed pairwise analysis of 87 CCOs and their matched primary tumors. The TIM type of the primary tumor was classified as immuno-active, immuno-exhausted, or immuno-desert. Results The gene expression profiles, signaling pathways, major oncogenic mutations, and histology of the CCOs recapitulated those of the primary tumors, but not the TIM of primary tumors. Two distinct intrinsic molecular subgroups of highly proliferative and mesenchymal phenotypes with clinical significance were identified in CCOs with various cancer signaling pathways. CCOs showed variable expression of cancer-specific immune-related genes such as those encoding HLA-I and HLA-II, and molecules involved in immune checkpoint activation/inhibition. Among these genes, the expression of HLA-II in CCOs was associated with favorable patient survival. K-means clustering analysis based on HLA-II expression in CCOs revealed a subgroup of patients, in whom cancer cells exhibited Intrinsically Immunogenic Properties (Ca-IIP), and were characterized by high expression of signatures associated with HLA-I, HLA-II, antigen presentation, and immune stimulation. Patients with the Ca-IIP phenotype had an excellent prognosis, irrespective of age, disease stage, intrinsic molecular type, or TIM status. Ca-IIP was negatively correlated with intrinsic E2F/MYC signaling. Analysis of the correlation between CCO immuno-genotype and TIM phenotype revealed that the TIM phenotype was associated with microsatellite instability, Wnt/β-catenin signaling, APC/KRAS mutations, and the unfolded protein response pathway linked to the FBXW7 mutation in cancer cells. However, Ca-IIP was not associated with the TIM phenotype. Conclusions We identified a Ca-IIP phenotype from a large set of CCOs. Our findings may provide an unprecedented opportunity to develop new strategies for optimal patient stratification in this era of immunotherapy.

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