Estimating time-dependent ROC curves using data under prevalent sampling

2016 ◽  
Vol 36 (8) ◽  
pp. 1285-1301
Author(s):  
Shanshan Li
Keyword(s):  
Roc Curves ◽  
Time Dependent ◽  
Using Data

Simulation of time-dependent movements in Syncrude tailings dyke foundation

1998 ◽  
Vol 35 (2) ◽  
pp. 284-298 ◽  
Author(s):  
AMP Wedage ◽  
N R Morgenstern ◽  
D H Chan
Keyword(s):  
Residual Strength ◽  
Time Dependent ◽  
Deformation Analysis ◽  
Foundation Soil ◽  
Clay Shale ◽  
Soil Plasticity ◽  
Rate Dependent ◽  
Rate Effects ◽  
Clearwater Formation ◽  
Using Data

Foundation movements at the Syncrude tailings dyke continued over several years in response to the construction of the dyke. Major movements have been observed in a relatively narrow layer of previously sheared clay-shale material of the Clearwater Formation. The residual strength of this highly plastic clay increases with the rate of shear. By reviewing the existing literature on the rate effects on residual strength and using data from new experiments on Clearwater Clay Shale, a general correlation between soil plasticity and rate effects is found. This rate dependence of the residual strength of Clearwater clay shale has been incorporated into a deformation analysis, which made it possible to compute time-dependent movements of the foundation soil to a satisfactory level. By using a rate-dependent plasticity model, a prediction of anticipated foundation velocities and how they decrease with time may be achieved.Key words: finite element, rate effects, residual strength, Syncrude tailings dyke, time-dependent movements.

P1017 EVALUATION OF THE PROGNOSTIC VALUE OF NON-INVASIVE LIVER FIBROSIS TESTS TO PREDICT MORTALITY BY TIME-DEPENDENT ROC CURVES

2014 ◽  
Vol 60 (1) ◽  
pp. S414
Author(s):  
S. Bertrais ◽  
J. Boursier ◽  
F. Oberti ◽  
I. Fouchard-Hubert ◽  
P. Calès
Keyword(s):  
Liver Fibrosis ◽  
Prognostic Value ◽  
Roc Curves ◽  
Time Dependent ◽  
Non Invasive

scholarly journals A Novel Nomogram Based on Hepatic and Coagulation Function for Evaluating Outcomes of Intrahepatic Cholangiocarcinoma After Curative Hepatectomy: A Multi-Center Study of 653 Patients

2021 ◽  
Vol 11 ◽  
Author(s):  
Yunshi Cai ◽  
Bohan Zhang ◽  
Jiaxin Li ◽  
Hui Li ◽  
Hailing Liu ◽  
...  
Keyword(s):  
Intrahepatic Cholangiocarcinoma ◽  
Calibration Curve ◽  
Prognostic Value ◽  
Roc Curves ◽  
Curve Analysis ◽  
Time Dependent ◽  
Decision Curve Analysis ◽  
Coagulation Function ◽  
Validation Set ◽  
Curative Hepatectomy

Background and AimsHepatic and coagulation function are routine laboratory tests prior to curative hepatectomy. The prognostic value of gamma-glutamyl transpeptidase (GGT) to platelet ratio (GPR) and international normalized ratio (INR) in surgically treated patients with intrahepatic cholangiocarcinoma (ICC) remains unclear.MethodsICC patients received curative hepatectomy in two west China centers were included. Time-dependent ROC curves were conducted to compare established indexes with prognostic value for ICC. GPR-INR score was introduced and evaluated using the Time-dependent AUC curve and Kaplan-Meier survival analysis. A novel nomogram based on the GPR-INR score was proposed; Harrell’s C-index, calibration curve and decision curve analysis were used to assess this nomogram.ResultsA total of 653 patients were included. The areas under ROC curves of GPR and INR in OS and RFS were superior to other indexes. Patients with a high GPR-INR score (1,2) presented significantly decreased overall survival (OS) and recurrence-free survival (RFS); GPR-INR sore, along with several clinicopathological indexes were selected into the nomogram, the calibration curve for OS probability showed good coincidence between the nomogram and the actual surveillance. The C-index of the nomogram was 0.708 (derivation set) and 0.746 (validation set), which was more representative than the C-indexes of the GPR-INR score (0.597, 0.678). In decision curve analysis, the net benefits of the nomogram in derivation and validation set were higher than Barcelona Clinic Liver Cancer staging (BCLC) classification and American Joint Committee on Cancer (AJCC) TNM 8th staging system.ConclusionsThe proposed nomogram generated superior discriminative ability to established staging systems; it is profitable to applicate this nomogram in clinical practice.

Modeling Tree Mortality Following Wildfire in Pinus ponderosa Forests in the Central Sierra-Nevada of California

1993 ◽  
Vol 3 (3) ◽  
pp. 139 ◽  
Author(s):  
JC Regelbrugge ◽  
SG Conard
Keyword(s):  
Sierra Nevada ◽  
Pinus Ponderosa ◽  
Tree Mortality ◽  
Fire Severity ◽  
Tree Height ◽  
Roc Curves ◽  
Stem Bark ◽  
Mortality Probability ◽  
Using Data ◽  
Bark Char

We modeled tree mortality occurring two years following wildfire in Pinus ponderosa forests using data from 1275 trees in 25 stands burned during the 1987 Stanislaus Complex fires. We used logistic regression analysis to develop models relating the probability of wildfire-induced mortality with tree size and fire severity for Pinus ponderosa, Calocedrus decurrens, Quercus chrysolepis, and Q. kelloggii. One set of models predicts mortality probability as a function of DBH and height of stem-bark char, a second set of models uses relative char height (height of stem-bark char as a proportion of tree height) as the predictor. Probability of mortality increased with increasing height of stem-bark char and decreased with increasing tree DBH and height. Analysis of receiver operating characteristic (ROC) curves indicated that both sets of models perform well for all species, with 83 to 96 percent concordance between predicted probabilities and observed outcomes. The models can be used to predict die probability of post-wildfire mortality of four tree species common in Pinus ponderosa forests in the central Sierra Nevada of California.

scholarly journals The Relationship between Age of Air and the Diabatic Circulation of the Stratosphere

2016 ◽  
Vol 73 (11) ◽  
pp. 4507-4518 ◽  
Author(s):  
Marianna Linz ◽  
R. Alan Plumb ◽  
Edwin P. Gerber ◽  
Aditi Sheshadri
Keyword(s):  
Steady State ◽  
General Circulation ◽  
Circulation Model ◽  
State Theory ◽  
Time Dependent ◽  
Absolute Value ◽  
Dependent Theory ◽  
The Difference ◽  
Using Data ◽  
The Relationship

Abstract The strength of the Brewer–Dobson circulation is difficult to estimate using observations. Trends in the age of stratospheric air, deduced from observations of transient tracers, have been used to identify trends in the circulation, but there are ambiguities in the relationship between age and the strength of the circulation. This paper presents a steady-state theory and a time-dependent extension to relate age of air directly to the diabatic circulation of the stratosphere. In steady state, it is the difference between the age of upwelling and downwelling air through an isentrope and not the absolute value of age that is a measure of the strength of the diabatic circulation through that isentrope. For the time-varying case, expressions for other terms that contribute to the age budget are derived. An idealized atmospheric general circulation model with and without a seasonal cycle is used to test the time-dependent theory and to find that these additional terms are small upon annual averaging. The steady-state theory holds as well for annual averages of a seasonally varying model as for a perpetual-solstice model. These results are a step toward using data to quantify the strength of the diabatic circulation.

scholarly journals Time-Effect of Donor and Recipient Characteristics on Graft Survival after Kidney Transplantation

2019 ◽  
Vol 28 (04) ◽  
pp. 249-254
Author(s):  
Jingyan Yang ◽  
Christine L. Sardo Molmenti ◽  
Joaquin Cagliani ◽  
Harish Datta ◽  
Elliot Grodstein ◽  
...  
Keyword(s):  
Graft Survival ◽  
Roc Curve ◽  
Operating Characteristic ◽  
Predictive Ability ◽  
Roc Curves ◽  
Time Dependent ◽  
First Year ◽  
Kidney Allocation System ◽  
Donor Characteristics ◽  
United Network

AbstractThe kidney allocation system (KAS) is based on quality-based “longevity matching” strategies that provide only a momentary snapshot of expected outcomes at the time of transplantation. The purpose of our study was to define on a continuous timeline the relative and mutual interactions of donor and recipient characteristics on graft survival.Total 39,108 subjects who underwent kidney transplant between October 25, 1999 and January 1, 2007 were identified in the United Network for Organ Sharing dataset. Our primary outcome was graft survival. Time-dependent receiver operating characteristic (ROC) curves and area under time-dependent ROC curve (AUC) were used to compare the predictive ability of the two allocation systems.During the first year after transplantation, both donor and recipient models showed identical relevance. From the first to the sixth years, although the two ROC curves were nearly identical, the donor model outweighed the recipient model. Both models intersected again at the sixth year. From that time onward, the ROC curve for recipient characteristics model predominated over the ROC curve for donor characteristics model. The predictive value of the recipient model (AUC = 0.752) was greater than that of the donor model (AUC = 0.673)We hope that this model will provide additional guidance and risk stratification to further optimize organ allocation based on the dynamic interaction of both donor and recipient characteristics over time.

Aluminium mass transfer and diffusion in water at 400–550°C, 2 kbar in the K2O–Al2O3–SiO2–H2O system driven by a thermal gradient or by a variation of temperature with time

1999 ◽  
Vol 63 (5) ◽  
pp. 633-647 ◽  
Author(s):  
O. Vidal ◽  
L. Durin
Keyword(s):  
Mass Transfer ◽  
Thermal Gradient ◽  
Transport Process ◽  
Laboratory Data ◽  
Time Dependent ◽  
Quantitative Interpretation ◽  
Rich Phase ◽  
High Fluid ◽  
Using Data ◽  
And Diffusion

AbstractTube-in-tube experiments involving a time-dependent variation of temperature or a strong thermal gradient were conducted in order to decipher the transport and transfer of Al in a closed medium along with dilute water. Results show that the solubility and the transport of Al are controlled by the alkali availability. Starting from a mixture of kyanite + quartz + muscovite at the hot end of a thermal gradient, Al is transported toward the cold end in the form of a complex with an Al/K stoichiometry close to unity. Since more Al than alkali are released by the dissolution of muscovite, an Al-rich phase (kyanite) forms in the vicinity of the starting minerals undergoing dissolution, although Al is mobile in the system. Then, the variation of the solubility of the Al-K complex with temperature leads to the formation of muscovite (+quartz) at the cold end of the thermal gradient. A quantitative interpretation of the experimental results was carried out using data from the literature on Al speciation in dilute water. Extrapolation of the laboratory data to natural rocks suggests that the diffusion of Al is an efficient transport process under medium-grade, low- to medium-pressure conditions. Therefore, mass-transfer estimates based on mass-balance analyses postulating a fixed Al reference frame should be considered with caution. Also the high fluid to rock ratio calculated from the amount of aluminosilicates occurring in veins of medium-grade metapelites is questionable because such calculations neglect the importance of the transport of Al by diffusion.

The role of breast-feeding beyond postpartum amenorrhoea on the return of fertility in India: a life table and hazards model analysis

1994 ◽  
Vol 26 (2) ◽  
pp. 191-206 ◽  
Author(s):  
Dilip C. Nath ◽  
Kenneth C. Land ◽  
Kaushalendra K. Singh
Keyword(s):  
Life Table ◽  
Breast Feeding ◽  
Model Analysis ◽  
Time Dependent ◽  
Birth Intervals ◽  
Feeding Duration ◽  
Hazards Model ◽  
Using Data ◽  
Resumption Of Menses

SummaryThis paper investigates the effects of continued breast-feeding after resumption of menses on fertility, using data from two retrospective surveys in India and single decrement life table and multivariate time-dependent hazards analyses. Breast-feeding even after the return of menses is found to be associated with longer birth intervals. The interaction of breast-feeding duration after resumption of menses and postpartum amenorrhoea has a significant effect on the risk of conception after return of menses.

scholarly journals COVID-19 vaccine effectiveness against laboratory confirmed symptomatic SARS-CoV-2 infection, COVID-19 related hospitalizations and deaths, among individuals aged 65 years or more in Portugal: a cohort study based on data-linkage of national registries February-September 2021

2021 ◽  
Author(s):  
Ausenda Machado ◽  
Irina Kislaya ◽  
Ana Paula Rodrigues ◽  
Duarte Sequeira ◽  
Joao Lima ◽  
...  
Keyword(s):  
Cox Regression ◽  
Viral Vector ◽  
Vaccine Effectiveness ◽  
Time Dependent ◽  
Unique Identifier ◽  
Symptomatic Infection ◽  
Age Cohorts ◽  
Electronic Health ◽  
Using Data

Background: Using data from electronic health registries, this study intended to estimate the COVID-19 vaccine effectiveness in the population aged 65 years and more, against symptomatic infection, COVID-19 related hospitalizations and deaths, overall and by time since complete vaccination. Methods: We stablished a cohort of individuals aged 65 and more years old, resident in Portugal mainland, using the National Health Service unique identifier User number to link eight electronic health registries. Outcomes included were symptomatic SARS-CoV-2 infections, COVID-19 related hospitalizations or deaths. The exposures of interest were the mRNA vaccines (Cominarty or Spikevax) and the viral vector Vaxzevria vaccine. Complete scheme vaccine effectiveness (VE) was estimated as one minus the confounder adjusted hazard ratio, for each outcome, estimated by time-dependent Cox regression with time dependent vaccine exposure. Results: For the cohort of individuals aged 65-79 years, complete scheme VE against symptomatic infection varied between 43% (Vaxzevria) and 65% (mRNA vaccines). This estimate was slightly lower in the ≥80 year cohort (53% for mRNA vaccines. VE against COVID-19 hospitalization varied between 89% (95%CI: 52-94) for Vaxzevria and 95% (95%CI: 93-97) for mRNA vaccines for the cohort aged 65-79 years and was 76% (95%CI: 67-83) for mRNA vaccines in the ≥80 year cohort. High VE against COVID-19 related deaths were estimated, for both vaccine types, 95% and 81% for the 65-79 years and the ≥80 year cohort, respectively. We observed a significant waning of VE against symptomatic infection, with VE estimates reaching approximately 34% for both vaccine types and cohorts. Significant waning was observed for the COVID-19 hospitalizations in the ≥80 year cohort (decay from 83% 14-41 days to 63% 124 days after mRNA second dose). No significant waning effect was observed for COVID-19 related deaths in the period of follow-up of either cohorts. Conclusions: In a population with a high risk of SARS-CoV-2 complications, we observed higher overall VE estimates against more severe outcomes for both age cohorts when compared to symptomatic infections. Considering the analysis of VE according to time since complete vaccination, the results showed a waning effect for both age cohorts in symptomatic infection and COVID-19 hospitalization for the 80 and more yo cohort.

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