21 research outputs found
Source rock/dispersed organic matter characterization-TSOP research subcommitee results
Because sedimentary organic matter consists of a diverse mixture of organic components with
different properties, a combination of chemical and petrographic results offers the most complete
assessment of source rock properties. The primary purpose of this Society for Organic Petrology (TSOP)
subcommittee is to contribute to the standardization of kerogen characterization methods. Specific
objectives include: (1) evaluation of the applications of different organic matter (petrographic) classifications
and terminology, and (2) integration of petrographic and geochemical results. These objectives
were met by completing questionnaires, and petrographic, geochemical and photomicrograph round-robin
exercises. Samples that were selected for this study represent different petrographic and geochemical
properties, and geologic settings to help identify issues related to the utilization of different classifications
and techniques. Petrographic analysis of the organic matter was completed using both a prescribed
classification and the individual classification normally used by each participant. Total organic carbon
(TOC), Rock-Eval pyrolysis and elemental analysis were also completed for each sample. Significant
differences exist in the petrographic results from both the prescribed and individual classifications.
Although there is general agreement about the oil- vs gas-prone nature of the samples, comparison of
results from individual classifications is difficult due to the variety of nomenclature and methods used to
describe an organic matter assemblage. Results from the photomicrograph exercise document that
different terminology is being used to describe the same component. Although variation in TOC and
Rock-Eval data exists, geochemical results define kerogen type and generative potential. Recommendations
from this study include:
(1) A uniform organic matter classification must be employed, which eliminates complex terminology
and is capable of direct correlation with geochemical parameters.
(2) A standardized definition and nomenclature must be used for the unstructured (amorphous)
organic matter category. Subdivisions of this generalized amorphous category are needed to
define its chemical and environmental properties.
(3) Standardized techniques including multimode illumination, types of sample preparations and
data reporting will help eliminate variability in the type and amount of organic components
reported
Source rock/dispersed organic matter characterization-TSOP research subcommitee results
Because sedimentary organic matter consists of a diverse mixture of organic components with
different properties, a combination of chemical and petrographic results offers the most complete
assessment of source rock properties. The primary purpose of this Society for Organic Petrology (TSOP)
subcommittee is to contribute to the standardization of kerogen characterization methods. Specific
objectives include: (1) evaluation of the applications of different organic matter (petrographic) classifications
and terminology, and (2) integration of petrographic and geochemical results. These objectives
were met by completing questionnaires, and petrographic, geochemical and photomicrograph round-robin
exercises. Samples that were selected for this study represent different petrographic and geochemical
properties, and geologic settings to help identify issues related to the utilization of different classifications
and techniques. Petrographic analysis of the organic matter was completed using both a prescribed
classification and the individual classification normally used by each participant. Total organic carbon
(TOC), Rock-Eval pyrolysis and elemental analysis were also completed for each sample. Significant
differences exist in the petrographic results from both the prescribed and individual classifications.
Although there is general agreement about the oil- vs gas-prone nature of the samples, comparison of
results from individual classifications is difficult due to the variety of nomenclature and methods used to
describe an organic matter assemblage. Results from the photomicrograph exercise document that
different terminology is being used to describe the same component. Although variation in TOC and
Rock-Eval data exists, geochemical results define kerogen type and generative potential. Recommendations
from this study include:
(1) A uniform organic matter classification must be employed, which eliminates complex terminology
and is capable of direct correlation with geochemical parameters.
(2) A standardized definition and nomenclature must be used for the unstructured (amorphous)
organic matter category. Subdivisions of this generalized amorphous category are needed to
define its chemical and environmental properties.
(3) Standardized techniques including multimode illumination, types of sample preparations and
data reporting will help eliminate variability in the type and amount of organic components
reported
Exonerees in Black and White: the influence of race on perceptions of those who falsely confessed to a crime
COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study
Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men
Thrombotic and hemorrhagic complications of COVID-19 in adults hospitalized in high-income countries compared with those in adults hospitalized in low- and middle-income countries in an international registry
Background: COVID-19 has been associated with a broad range of thromboembolic, ischemic, and hemorrhagic complications (coagulopathy complications). Most studies have focused on patients with severe disease from high-income countries (HICs). Objectives: The main aims were to compare the frequency of coagulopathy complications in developing countries (low- and middle-income countries [LMICs]) with those in HICs, delineate the frequency across a range of treatment levels, and determine associations with in-hospital mortality. Methods: Adult patients enrolled in an observational, multinational registry, the International Severe Acute Respiratory and Emerging Infections COVID-19 study, between January 1, 2020, and September 15, 2021, met inclusion criteria, including admission to a hospital for laboratory-confirmed, acute COVID-19 and data on complications and survival. The advanced-treatment cohort received care, such as admission to the intensive care unit, mechanical ventilation, or inotropes or vasopressors; the basic-treatment cohort did not receive any of these interventions. Results: The study population included 495,682 patients from 52 countries, with 63% from LMICs and 85% in the basic treatment cohort. The frequency of coagulopathy complications was higher in HICs (0.76%-3.4%) than in LMICs (0.09%-1.22%). Complications were more frequent in the advanced-treatment cohort than in the basic-treatment cohort. Coagulopathy complications were associated with increased in-hospital mortality (odds ratio, 1.58; 95% CI, 1.52-1.64). The increased mortality associated with these complications was higher in LMICs (58.5%) than in HICs (35.4%). After controlling for coagulopathy complications, treatment intensity, and multiple other factors, the mortality was higher among patients in LMICs than among patients in HICs (odds ratio, 1.45; 95% CI, 1.39-1.51). Conclusion: In a large, international registry of patients hospitalized for COVID-19, coagulopathy complications were more frequent in HICs than in LMICs (developing countries). Increased mortality associated with coagulopathy complications was of a greater magnitude among patients in LMICs. Additional research is needed regarding timely diagnosis of and intervention for coagulation derangements associated with COVID-19, particularly for limited-resource settings
Characteristics and outcomes of an international cohort of 600 000 hospitalized patients with COVID-19
Background: We describe demographic features, treatments and clinical outcomes in the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) COVID-19 cohort, one of the world’s largest international, standardized data sets concerning hospitalized patients. Methods: The data set analysed includes COVID-19 patients hospitalized between January 2020 and January 2022 in 52 countries. We investigated how symptoms on admission, co-morbidities, risk factors and treatments varied by age, sex and other characteristics. We used Cox regression models to investigate associations between demographics, symptoms, co-morbidities and other factors with risk of death, admission to an intensive care unit (ICU) and invasive mechanical ventilation (IMV). Results: Data were available for 689 572 patients with laboratory-confirmed (91.1%) or clinically diagnosed (8.9%) SARS-CoV-2 infection from 52 countries. Age [adjusted hazard ratio per 10 years 1.49 (95% CI 1.48, 1.49)] and male sex [1.23 (1.21, 1.24)] were associated with a higher risk of death. Rates of admission to an ICU and use of IMV increased with age up to age 60 years then dropped. Symptoms, co-morbidities and treatments varied by age and had varied associations with clinical outcomes. The case-fatality ratio varied by country partly due to differences in the clinical characteristics of recruited patients and was on average 21.5%. Conclusions: Age was the strongest determinant of risk of death, with a ~30-fold difference between the oldest and youngest groups; each of the co-morbidities included was associated with up to an almost 2-fold increase in risk. Smoking and obesity were also associated with a higher risk of death. The size of our international database and the standardized data collection method make this study a comprehensive international description of COVID-19 clinical features. Our findings may inform strategies that involve prioritization of patients hospitalized with COVID-19 who have a higher risk of death