Four-component Model Research Articles

Testing models for the compositions of chondrites and their components: II. CR chondrites

Knowing how the major chondritic components evolved and what their initial compositions were is pivotal for our understanding of the processes that shaped the early Solar System. Here, we have extended to the CR chondrites our testing of chondrule-matrix complementarity and the four-component model, i.e., two very different explanations for the bulk compositions of the carbonaceous chondrites and their components. Combining point-counting with electron microprobe analyses, we have analyzed four relatively primitive Antarctic CRs and the fall Renazzo. Our results for the abundances of chondrules and matrix are in good agreement with literature data, and confirm that these abundances vary considerably amongst the CRs (80.4 ± 2.3 wt.% and 18.5 ± 2.8 wt.%, respectively, in the four Antarctic CRs vs. 62.3 ± 3.4 wt.% and 33.2 ± 2.2 wt.% in Renazzo). The significant differences make the determination of the average properties and bulk compositions of the CRs problematic. This is particularly true for the volatile elements that were predominantly accreted in matrix. Nevertheless, all major and many minor element concentrations reported in the literature for average bulk CRs are reproduced here to better than 10%. By comparing our results to conventionally determined bulk compositions, we were able to verify the accuracy of our approach and identify elements likely affected by alteration or analytical artifacts (e.g., Ti, K, Co). Two particular compositional details of the CR chondrites investigated are (a) the relatively high contents of Mn in the chondrules compared to CO chondrules, and (b) the depletion of S in the matrix, relative to CI. In terms of the major elements Mg, Al, Si and Ca, our data suggest that unaltered chondrules and matrix exhibited CI-like relative abundances, supporting previous conclusions for the CO chondrites. Where observed, deviations of element abundances in the matrix from CI (Na, Mg, S, Ca, Fe, Ni) can be explained in terms of alteration (parent body and terrestrial) and pre-accretionary loss of forsterite and, possibly, sulfides. Overall, our results are more consistent with the predictions of the four-component model than they are with chondrule-matrix complementarity.

Modeling of wellbore multiphase flow with free gas influx during horizontal drilling in marine hydrate reservoirs

The wellbore multiphase flow and managed annulus pressure are key issues during drilling in hydrate reservoirs. In this study, the intercoupling interactions of free gas, drilling fluid, cuttings, and hydrates are considered, and a gas–liquid–solid multiphase four-component flow model that incorporates the hydrate phase transition is proposed. The hydrate formation and multiphase flow submodels in the unified model were verified by comparing with the collected data from a hydrate formation experiment in a flow loop and a full-scale gas kick experiment, respectively. The multiphase flow behaviors and gas kick migration, as well as the effects of hydrate phase transition, were thoroughly analyzed. Simulation results show that the hydrate decomposition in the cuttings is sufficient to cause a pit gain of 1.96 m3, which is approximately equal to that of a 3 MPa bottomhole underbalanced pressure. Thus, failure to consider this factor in multiphase flow simulation will result in significant errors in the bottomhole and formation pressure inversion. The phase transition of hydrates delay the pit gain in reaching 1 m3 by 32 min. The prediction errors of the pit gain and outlet flow rate at the initial stage of overflow can reach up to 94.33% and 6.17%, respectively, when the hydrate phase transition is neglected. Using managed pressure drilling and increasing the wellhead pressure to 1.5 MPa in the case study can ensure that the gas void fraction in the annulus is within a controllable range. This unified model can provide insights into gas kick migration and wellbore pressure control for horizontal well drilling in hydrate reservoirs.

Значение медиаграмотности для политической коммуникации в России

The article analyses the role and importance of media literacy for political communication in Russia using the example of student life. The purpose of this article is to develop and test a new model of political communication with an emphasis on media literacy as a factor in the dissemination of political information in society. This approach opens up new perspectives for the study of political communication by the public. The authors have developed a four-component model of political communication, which includes the following components: socio-demographic data, media literacy, media effects and political behavior. This model was tested in an online survey on student media literacy in Russia and its impact on political communication (N = 632). The article also uses data from open sources and databases. Using the Chi-square test, it was found that media literacy, as a factor in political communication, plays a more important role than socio-demographic characteristics. In other words, media literacy is much better at explaining media effects and political behavior than the socio-demographic profile of the respondents. This conclusion, of course, applies only to student youth in Russia and needs further empirical verification.

Radiocarbon age offsets, ontogenetic effects, and potential old carbon contributions from soil organic matter for pre-bomb and modern detritivorous gastropods from central Texas, USA

Carbon isotopes of terrestrial gastropod yield insights on age and paleoenvironments for many depositional settings, but questions remain on the carbon source for gastropod carbonate and the climatic significance. This study documented for four terrestrial gastropod species ( Rabdotus dealbatus, A. alternata, V. indentata, and Rumina decollata) from central Texas 14 C age offsets between shell‑carbonate and corresponding atmosphere values that lived on carbonate- and kerogen-rich Cretaceous bedrock in the 20th and 21st centuries. Also, the ontogenetic variations in 14 C content were assessed to better understand carbon cycling between gastropods and the associated reservoirs. The carbon sources were partitioned based on 13 C isotopic values to evaluate the possible causes for age anomalies using initially a three-component model that includes contributions from atmosphere, vegetation, and limestone pools, with a new added fourth component, for soil organic carbon. The average ( n = 4) of the outer and inner shell samples yielded the respective 14 C ages of 550 ± 325 and 1520 ± 525 yr B.P. The apparent linearized 14 C distance-age anomaly for an individual gastropod whorl is 4–26 mm/yr calculate from shell 14 C ages on apex and aperture material. The smallest gastropod dated, a single V. indentata test (3.9 mg) yielded the oldest 14 C age of 2340 yr B.P. The four-component model for the oldest 14 C ages indicates that 50–85% of shell carbon may be from ingestion, with a smaller pool from respiration. Up to 30% of the organic carbon in gastropod shell may be derived from soil organic carbon. Terrestrial gastropods that yield anomalously old 14 C ages of >500 years may be detritivores and live in soils with sources of labile old carbon either inherited from the bedrock and/or the older pool of soil organic matter common in well-developed calcium-rich soils. • Modern and prebomb terrestrial gastropods from Texas gave 14 C ages 300–2400 yr old. • Gastropod shells show ontogenetic effect with older ages at apex by 100–1700 yr. • Identify new old carbon source for snails from kerogen-rich soil organic matter (SOM) • Develop new four component model (air, rock, SOM and plants) to explain old 14 C ages • Up to 30% of carbon in gastropod shell may be derived from SOM.

Development and Validation of a Quantitative Research Literacy Questionnaire

Simultaneous with the emergence of numerous new concerns and techniques in carrying out research in English language teaching (ELT) contexts, conducting ELT research has turned into a multi-dimensional process, and ELT researchers seem to require advanced research skills in order to address different pedagogical issues. Focusing on quantitative research, the present study was undertaken to develop and validate a quantitative research literacy (QRL) instrument for English as a foreign language (EFL) teacher training context. To this objective, a four-component model of QRL, encompassing developing research topic knowledge, research design knowledge, procedural knowledge, and data analysis knowledge was developed based on experts’ opinion and an extensive review of the related literature. Testing of the tentative model through exploratory and confirmatory data analyses on a sample of 1180 EFL teachers across three education levels indicated that a 4-factor model of QRL with 9 sub-factors and 50 items could best explain QRL.

Bayesian Analysis of Cancer Data Using a 4-Component Exponential Mixture Model.

Cancer is among the major public health problems as well as a burden for Pakistan. About 148,000 new patients are diagnosed with cancer each year, and almost 100,000 patients die due to this fatal disease. Lung, breast, liver, cervical, blood/bone marrow, and oral cancers are the most common cancers in Pakistan. Perhaps smoking, physical inactivity, infections, exposure to toxins, and unhealthy diet are the main factors responsible for the spread of cancer. We preferred a novel four-component mixture model under Bayesian estimation to estimate the average number of incidences and death of both genders in different age groups. For this purpose, we considered 28 different kinds of cancers diagnosed in recent years. Data of registered patients all over Pakistan in the year 2012 were taken from GLOBOCAN. All the patients were divided into 4 age groups and also split based on genders to be applied to the proposed mixture model. Bayesian analysis is performed on the data using a four-component exponential mixture model. Estimators for mixture model parameters are derived under Bayesian procedures using three different priors and two loss functions. Simulation study and graphical representation for the estimates are also presented. It is noted from analysis of real data that the Bayes estimates under LINEX loss assuming Jeffreys' prior is more efficient for the no. of incidences in male and female. As far as no. of deaths are concerned again, LINEX loss assuming Jeffreys' prior gives better results for the male population, but for the female population, the best loss function is SELF assuming Jeffreys' prior.

Productivity and Efficiency of Precision Farming: The Case of Czech Cereal Production

The paper deals with the sources of competitiveness of Czech cereal production by considering precision farming technology and employing micro-level data collected in the FADN database for the period 2005–2018. The analysis is based on the stochastic frontier modelling of an input distance function in the specification of the four-component model, which currently represents the most advanced approach to technical efficiency analysis. To provide a robust estimate of the model, the paper employs methods which control for the potential endogeneity of netputs in the four-step estimation procedure. Furthermore, the total factor productivity change is calculated using the Törnqvist-Theil index. The results reveal that Czech cereal producers took great advantage of their production possibilities and experienced technological progress, which contributed considerably to productivity dynamics and consequently to an increase in their competitiveness. Precision farming, which is associated with a large number of innovations reflected in technological change and optimal resource use, contributed to higher technical efficiency connected with cost savings in Czech cereal production.

Biology Students’ Morality When Engaged With Moral Dilemmas in the Human-Nature Context

Framed within the Four Component Model (FCM) of morality, this case study investigates the nature of Dutch 15–16 years old biology students’ morality in socioscientific issues in the human-nature context. In doing so, we discuss the morality of 12 students with data collected through individual semi-structured interviews following the implementation of a specially-designed curriculum. During the interviews the students discussed a moral dilemma related to the rehabilitation of seals. The findings indicate that students demonstrated aspects of all four FCM components. The students placed themselves in the perspectives of involved stakeholders, both affectively and cognitively. In addition, the students exhibited both rationality-based and emotion-based moral reasoning. A number of students experienced an “inner conflict” between cognitive and emotional reasoning, which affected their moral motivation and–as such–represented their moral reflection process. Students’ moral emotions were often decisive in their moral decision-making. Among the different kinds of moral emotions (compassion, guilt, duty, respect), compassion appeared most. The findings are discussed alongside implications for future research with a focus on encouraging aspects of students’ morality, which are an important part of citizenship skills.

UV-based advanced oxidation of dissolved organic matter in reverse osmosis concentrate from a potable water reuse facility: A Parallel-Factor (PARAFAC) analysis approach

Disposal of reverse osmosis concentrate (ROC) from advanced water purification facilities is a challenge associated with the implementation of reverse osmosis-based treatment of municipal wastewater effluent for potable reuse. In particular, the dissolved organic matter (DOM) present in ROC diminishes the quality of the receiving water upon environmental disposal and affects the toxicity, fate, and transport of organic contaminants. This study investigates UV-based advanced oxidation processes (UV-AOPs) for treating DOM in ROC using a Parallel Factor Analysis (PARAFAC) approach. DOM composition and degradation were tested in UV-only and three UV-AOPs using hydrogen peroxide (H2O2), free chlorine (Cl2), and persulfate (S2O82−). The four-component PARAFAC model consisted of two terrestrial humic-like components (CUVH and CVisH), a wastewater/nutrient tracer component (CNuTr), and a protein-like (tyrosine-like) component (CPrTy). Based on the observed loss in the maximum fluorescence intensity of the components, DOM degradation was determined to be dependent on UV fluence, oxidant dose, and dilution factor of the ROC (i.e., bulk DOM concentration). CVisH was most the photolabile component in the UV-only system, followed by CNuTr, CPrTy, and CUVH, respectively. Furthermore, UV-H2O2 and UV-S2O82− displayed faster overall reaction kinetics compared to UV-Cl2. The degradation trends suggested that CNuTr and CPrTy consisted of chemical moieties that were susceptible to reactive oxygen species (HO•) but not reactive chlorine species; whereas, CVisH was sensitive to all reactive species generated in the three UV-AOPs. Compared to other components, CPrTy was recalcitrant in all treatment scenarios tested. Calculations using chemical probe-based analysis also confirmed these trends in the reactivity of DOM components. The outcomes of this study form a foundation for characterizing ROC reactivity in UV-AOP treatment technologies, to ultimately improve the sustainability of water reuse systems.

TFP growth, technical efficiency and catch-up dynamics: Evidence from Indian manufacturing

Recent studies have shown that technical efficiency can be both persistent (long-term) and transient (short-term). However, their dynamics are under-examined compared to conventional technical efficiency. This study investigates the dynamics of both persistent and transient technical efficiencies and TFP growth in the Indian manufacturing sector. Using data on 10667 firms in 17 industries over 1999–2018, we employ a four-component stochastic frontier model to separate the persistent technical efficiency from the firm heterogeneity and the transient technical efficiency from the random noise. Results support the existence of both conditional and unconditional beta convergence in transient technical efficiency, indicating a catching-up by transiently inefficient firms. Convergence speed remains unaffected by firm characteristics; however, it slowed after the 2008-financial crisis. Results also show that with time persistently inefficient firms exit the market. Finally, the study investigates the drivers of TFP growth. We show that technical change and efficiency improvement drive the TFP growth.

Tracking changes in body composition: comparison of methods and influence of pre-assessment standardisation.

The present study reports the validity of multiple assessment methods for tracking changes in body composition over time and quantifies the influence of unstandardised pre-assessment procedures. Resistance-trained males underwent 6 weeks of structured resistance training alongside a hyperenergetic diet, with four total body composition evaluations. Pre-intervention, body composition was estimated in standardised (i.e. overnight fasted and rested) and unstandardised (i.e. no control over pre-assessment activities) conditions within a single day. The same assessments were repeated post-intervention, and body composition changes were estimated from all possible combinations of pre-intervention and post-intervention data. Assessment methods included dual-energy X-ray absorptiometry (DXA), air displacement plethysmography, three-dimensional optical imaging, single- and multi-frequency bioelectrical impedance analysis, bioimpedance spectroscopy and multi-component models. Data were analysed using equivalence testing, Bland-Altman analysis, Friedman tests and validity metrics. Most methods demonstrated meaningful errors when unstandardised conditions were present pre- and/or post-intervention, resulting in blunted or exaggerated changes relative to true body composition changes. However, some methods - particularly DXA and select digital anthropometry techniques - were more robust to a lack of standardisation. In standardised conditions, methods exhibiting the highest overall agreement with the four-component model were other multi-component models, select bioimpedance technologies, DXA and select digital anthropometry techniques. Although specific methods varied, the present study broadly demonstrates the importance of controlling and documenting standardisation procedures prior to body composition assessments across distinct assessment technologies, particularly for longitudinal investigations. Additionally, there are meaningful differences in the ability of common methods to track longitudinal body composition changes.

Identifying Mixture Components From Large-Scale Keystroke Log Data.

In a computer-based writing assessment, massive keystroke log data can provide real-time information on students’ writing behaviors during text production. This research aims to quantify the writing process from a cognitive standpoint. The hope is that the quantification may contribute to establish a writing profile for each student to represent a student’s learning status. Such profiles may contain richer information to influence the ongoing and future writing instruction. Educational Testing Service (ETS) administered the assessment and collected a large sample of student essays. The sample used in this study contains nearly 1,000 essays collected across 24 schools in 18 U.S. states. Using a mixture of lognormal models, the main findings show that the estimated parameters on pause data are meaningful and interpretable with low-to-high cognitive processes. These findings are also consistent across two writing genres. Moreover, the mixture model captures aspects of the writing process not examined otherwise: (1) for some students, the model comparison criterion favored the three-component model, whereas for other students, the criterion favored the four-component model; and (2) students with low human scores have a wide range of values on the mixing proportion parameter, whereas students with higher scores do not possess this pattern.

The Effect of Restructuring Electricity Distribution Systems on Firms’ Persistent and Transient Efficiency: The Case of Germany

We evaluate the efficiency of electricity distribution operators (DSOs) as providers of local public infrastructure. In particular, we consider two types of efficiency, i.e., short-term (transient) and long-term (persistent). We apply the recently developed four-component stochastic frontier model, which allows identifying determinants of the two types of efficiency, after controlling for firm heterogeneity and random noise, to a panel dataset of German DSOs observed during 2006-2012.Those DSOs operating in the eastern parts of Germany have undergone a profound restructuring after the reunification in 1990. We find that this was beneficial for their efficiency as they perform, on average, better in terms of persistent efficiency than DSOs in West Germany. Both eastern and western DSOs perform similarly well in terms of transient efficiency, which is expected as the sector is highly regulated. As such, we provide new insights on identifying the nature and sources of public infrastructure productive inefficiency, which is relevant for public policies.

Optimal scheduling of the next preventive maintenance activity for a wind farm

Abstract. A large part of the operational cost for a wind farm is due to the cost of equipment maintenance, especially for offshore wind farms. How to reduce the maintenance cost, and hence increase profitability, is this article's focus. It presents a binary linear optimization model whose solution may inform the wind turbine owners about which components, and when, should undergo the next preventive maintenance (PM) replacements. The suggested short-term scheduling strategy takes into account eventual failure events of the multi-component system – in that after the failed system is repaired, the previously scheduled PM plan should be updated, assuming that the restored components are as good as new. The optimization algorithm of this paper, NextPM, is tested through numerical case studies applied to a four-component model of a wind turbine. The first study addresses the important case of a single component system, used for parameter calibration purposes. The second study analyses the case of seasonal variations of mobilization costs, as compared to the constant mobilization cost setting. Among other things, this analysis reveals a 35 % cost reduction achieved by the NextPM model, as compared to the pure corrective maintenance (CM) strategy. The third case study compares the NextPM model with another optimization model – the preventive maintenance scheduling problem with interval costs (PMSPIC), which was the major source of inspiration for this article. This comparison demonstrates that the NextPM model is accurate and much faster in terms of computational time.

ABOUT THE PARAMETERS OF THE DIELECTRIC MODEL OF SOILS USED IN THE SMOS ALGORITHM

The features of the four-component refractive dielectric model of moist soils are considered. Typical values of the parameters of the Debye model of bound water obtained by processing experimental data using this model are given. The reasons why the parameters of the Debye model of free soil water in this model differ from the true values of these parameters are explained. It is shown that the excess of the static permeability and specific conductivity values relative to the true values is caused by the Maxwell – Wagner relaxation process with a relaxation time of sev-eral nanoseconds.

Four-component instructional design (4C/ID) model: a meta-analysis on use and effect

The four-component instructional design model (4C/ID) has been increasingly used in face-to-face and online learning environments. We present a meta-analysis on the use and effect on performance of educational programs developed with the 4C/ID model after more than 20 years of its application and research in different academic areas and technical training. We performed the meta-analysis through the combination of effect sizes from studies using Cohen’s d. The combination of the studies suggests that the use of educational programs developed with 4C/ID has a high impact on performance (d = 0.79 standard deviations), regardless of the academic area, the design of the study and the outcome (knowledge and complex skills). The grade under study was a significant moderator on the effect, showing that the higher-education level is more suitable for application of the 4C/ID model. Our results suggest that the use of the 4C/ID model should be prioritized as an instructional model in college and university learning environments.

Removal of disinfection by-product precursors in drinking water treatment processes: Is fluorescence parallel factor analysis a promising indicator?

This work investigated the removal efficiency of disinfection by-product (DBP) precursors by different drinking water treatment processes and evaluated the feasibility of using fluorescence components removal as an indicator. A four-component (including tryptophan-like, protein-bound, tyrosine-like, and humic-like components) parallel factor analysis model was developed basing on 288 fluorescence excitation-emission matrices. Among all treatment processes, coagulation-sedimentation process showed the best performance, with mean removal ratios of 30% in total fluorescence intensity and 31% in total formation potential (FP) of DBPs, respectively. It preferentially removed humic-like component C4 (43%). Advanced treatment processes were less effective in comparison. Ozone and biological activated carbon (BAC) combined process reduced 20% of total fluorescence intensity, while ultrafiltration process reduced < 3%. Ozonation and BAC filtration preferentially removed free amino acids (i.e., C1 and C3) and protein-bound (i.e., C2) components, with mean removal ratios of 12% and 17%, respectively. Significant correlations (p < 0.01, double-tailed) were observed between four fluorescence components removal and FPs reduction of three trihalomethanes, dichloroacetonitrile (DCAN), and 1,1-dichloropropanone (1,1-DCP). Specifically, the correlation coefficients for three trihalomethanes and 1,1-DCP followed the order of C4 > C1 > C2 > C3, while the order for DCAN was C2 > C4 > C1 > C3.

A - 07 Post-Concussion Symptom Scale Factors Shift with Longer Time Since Injury in Adolescents with Sport-Related Concussion

Abstract Objective To evaluate the role of time since injury on the factor structure of the Post-Concussion Symptom Scale (PCSS) for athletes after sustaining a sport-related concussion (SRC). Methods Adolescent athletes (n = 782) were dichotomized based on time since injury: 0–7 (EARLY; n = 321, age: 15.4 ± 1.9 years, 51.7% female), 8–14 (MIDDLE; n = 281, age: 15.8 ± 2.2 years, 54.8% female) and 15–30 days (LATE; n = 180, age: 15.6 ± 1.8 years, 52.8% female). An EFA was performed on the 22 variables of the PCSS for each of the three cohorts (primary factor loading of 0.6 to retain each item). Results EARLY had a five-component model (64% of total variance): 1) GLOBAL (18.0%; headache/dizziness/photosensitivity/phonosensitivity/difficulty concentrating), 2) FATIGUE/HYPERSOMNIA (16.4%; fatigue/drowsiness/mental fogginess/slowed down/hypersomnia), 3) AFFECTIVE (12.6%; more emotional/sadness), 4) INSOMNIA (9.0%; insomnia/trouble falling asleep), 5) SOMATIC (8.0%; vomiting/numbness). MIDDLE had a four-component model (63.1% of variance): 1) GLOBAL (19.4%; photosensitivity/headache/phonosensitivity/nausea/dizziness), 2) INSOMNIA/AFFECTIVE (14.4%; insomnia/more emotional/nervousness/trouble falling asleep), 3) SOMATIC/MEMORY (12.2%; difficulty remembering/numbness), and 4) HYPERSOMNIA (12.0%; drowsiness/hypersomnia). LATE had a four-component model (65.7% of variance): 1) VESTIBULAR/OCULAR (18.2%; vision/difficulty remembering/balance/fogginess/dizziness), 2) MIGRAINE (16.6%; photosensitivity/phonosensitivity/fatigue/headache), 3) AFFECTIVE (16.1%; sadness/nervousness/more emotional), and 4) INSOMNIA (7.6%; insomnia/trouble falling asleep). Conclusions The results of this study suggest greater time since injury modifies symptom factor structure in adolescent athletes with SRC. Specifically, symptom factors become more distinct with longer time since injury before first clinical visit. A GLOBAL symptom factor was observed for both EARLY and MIDDLE, but not in LATE. SOMATIC (i.e., numbness) was observed in EARLY/MIDDLE, but not LATE. Symptom factors in LATE seem to mirror concussion clinical sub-types from previous research (e.g., vestibular/ocular, migraine, affective, sleep).

The effects of suprathermal particles on the existence domain of oblique low-frequency solitary waves in multi-component magnetospheric plasmas

The effect of suprathermal particles is examined on arbitrary amplitude nonlinear low-frequency electrostatic solitary waves propagating obliquely to the ambient magnetic field of the terrestrial magnetosphere using the Sagdeev pseudopotential formalism. The four-component plasma model consists of cold singly charged oxygen ions, hot protons, and two distinct groups of electrons with the latter three having kappa velocity distributions. Our numerical investigations based on comparatively low values for the spectral indices of the two electron species and the hot proton distributions as inferred from time history of events and macroscale interactions during substorms mission data reveal that the coexistence of compressive and rarefactive solitons is suppressed in comparison to the behavior in the presence of Maxwellian species (infinitely large values of kappa). Also, the existence of positive potential solitons is suppressed in an intermediate range of cold oxygen-ion densities. The differences are attributed to the occurrence of singularities in the Sagdeev potential for the chosen set of spectral indices.

Testing models for the compositions of chondrites and their components: I. CO chondrites

We present the first results of a comprehensive investigation aimed at testing the hypothesis of chondrule-matrix complementarity and the four-component model for the compositions of the carbonaceous chondrites and their components. Combining point-counting with electron microprobe analyses, we have determined the bulk compositions of thin sections, as well as the average abundances and compositions of the major chondritic components (chondrules, matrix, refractory inclusions, isolated silicate grains and isolated opaque grains). To minimize the potential for element exchange between components during parent body processing, the two most primitive COs, DOM 08006 and ALH 77307, and the primitive ungrouped CO/CM-like Acfer 094 were selected for this study. To verify our method, we also examined one section of the well-studied CO3.2 Kainsaz, a fall that is free of weathering. We were able to reproduce all major and many minor elemental concentrations reported in the literature for average bulk COs and Kainsaz to better than 10%. The elements most commonly cited as displaying evidence for complementarity are Mg, Si, Al, Ca, Fe and Ti. Iron, however, can be easily affected by chondrule metal-silicate fractionation, redistribution in the parent body and weathering, and our Ti data for matrix are likely compromised by an analytical artifact. Hence, we focused on Mg, Al, Si and Ca – four elements that we can determine very accurately – and show that their relative abundances in chondrules are on average CI-like within the uncertainties of the method. The matrix is not CI-like, but its composition can be explained by the loss of 10–15 wt.% of forsterite from an initially CI-like material prior to or during parent body accretion. These results are inconsistent with chondrule-matrix complementarity. Our average CO chondrule compositions, as well as chondrule and matrix abundances, are in line with the predictions of the four-component model. However, the four-component model assumes a CI-like composition for matrix, and also predicts refractory inclusion abundances that are higher and compositions that are less refractory than we observe. While similar studies of the other carbonaceous chondrite groups are needed, these differences may indicate the limitations of the simplifying assumptions made in the four-component model.