Optimum Threshold Minimizes Noise in Timing of Intracellular Events

Abstract Background Circulating tumor cells (CTCs) are detectable in patients with neuroendocrine tumors (NETs) and are accurate prognostic markers although the optimum threshold has not been defined. Objective This work aims to define optimal prognostic CTC thresholds in PanNET and midgut NETs. Patients and Methods CellSearch was used to enumerate CTCs in 199 patients with metastatic pancreatic (PanNET) (90) or midgut NETs (109). Patients were followed for progression-free survival (PFS) and overall survival (OS) for a minimum of 3 years or until death. Results The area under the receiver operating characteristic curve (AUROC) for progression at 12 months in PanNETs and midgut NETs identified the optimal CTC threshold as 1 or greater and 2 or greater, respectively. In multivariate logistic regression analysis, these thresholds were predictive for 12-month progression with an odds ratio (OR) of 6.69 (P < .01) for PanNETs and 5.88 (P < .003) for midgut NETs. The same thresholds were found to be optimal for predicting death at 36 months, with an OR of 2.87 (P < .03) and 5.09 (P < .005) for PanNETs and midgut NETs, respectively. In multivariate Cox hazard regression analysis for PFS in PanNETs, 1 or greater CTC had a hazard ratio (HR) of 2.6 (P < .01), whereas 2 or greater CTCs had an HR of 2.25 (P < .01) in midgut NETs. In multivariate analysis OS in PanNETs, 1 or greater CTCs had an HR of 3.16 (P < .01) and in midgut NETs, 2 or greater CTCs had an HR of 1.73 (P < .06). Conclusions The optimal CTC threshold to predict PFS and OS in metastatic PanNETs and midgut NETs is 1 and 2, respectively. These thresholds can be used to stratify patients in clinical practice and clinical trials.

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A multiple threshold method for fitting the generalized Pareto distribution and a simple representation of the rainfall process

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-4957-2010 ◽

2010 ◽

Vol 7 (4) ◽

pp. 4957-4994 ◽

Cited By ~ 5

Author(s):

R. Deidda

Keyword(s):

Time Series ◽

Distribution Function ◽

Pareto Distribution ◽

Generalized Pareto Distribution ◽

Daily Rainfall ◽

Rainfall Time Series ◽

Threshold Method ◽

Generalized Pareto ◽

Multiple Threshold ◽

Optimum Threshold

Abstract. Previous studies indicate the generalized Pareto distribution (GPD) as a suitable distribution function to reliably describe the exceedances of daily rainfall records above a proper optimum threshold, which should be selected as small as possible to retain the largest sample while assuring an acceptable fitting. Such an optimum threshold may differ from site to site, affecting consequently not only the GPD scale parameter, but also the probability of threshold exceedance. Thus a first objective of this paper is to derive some expressions to parameterize a simple threshold-invariant three-parameter distribution function which is able to describe zero and non zero values of rainfall time series by assuring a perfect overlapping with the GPD fitted on the exceedances of any threshold larger than the optimum one. Since the proposed distribution does not depend on the local thresholds adopted for fitting the GPD, it will only reflect the on-site climatic signature and thus appears particularly suitable for hydrological applications and regional analyses. A second objective is to develop and test the Multiple Threshold Method (MTM) to infer the parameters of interest on the exceedances of a wide range of thresholds using again the concept of parameters threshold-invariance. We show the ability of the MTM in fitting historical daily rainfall time series recorded with different resolutions. Finally, we prove the supremacy of the MTM fit against the standard single threshold fit, often adopted for partial duration series, by evaluating and comparing the performances on Monte Carlo samples drawn by GPDs with different shape and scale parameters and different discretizations.

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An Improved Adaptive Threshold Skin Color Model

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.610.358 ◽

2014 ◽

Vol 610 ◽

pp. 358-361

Author(s):

Hong Wei Di ◽

Wei Xu

Keyword(s):

Skin Color ◽

Adaptive Threshold ◽

Experimental Results ◽

Color Model ◽

Threshold Segmentation ◽

Change Rate ◽

Skin Segmentation ◽

Strong Robustness ◽

Skin Color Model ◽

Optimum Threshold

To solve the problem that traditional threshold segmentation model is not very robust in skin segmentation under different skin colors and different illuminations, an improved adaptive skin color model is proposed. This model detects the change rate of the skin color pixels by modifying the certain threshold while fixing others, then selects the optimum threshold adaptively. The experimental results show that this algorithm can effectively distinguish skin color regions and background regions, and has strong robustness on light disturbance.

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Prediction of pathological fracture in patients with metastatic disease of the lower limb

Scientific Reports ◽

10.1038/s41598-019-50636-9 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 7

Author(s):

Emma L. Howard ◽

Paul Cool ◽

Gillian L. Cribb

Keyword(s):

Body Weight ◽

Metastatic Disease ◽

Lower Limb ◽

Prospective Observational Study ◽

Pathological Fracture ◽

Weight Bearing ◽

Total Body Weight ◽

Threshold Level ◽

Total Body ◽

Optimum Threshold

Abstract The aim of this study was to investigate if the risk of pathological fracture can be predicted with the proportion of body weight that can be put through the affected leg in patients with metastatic bone disease of the lower limb. A prospective observational study was conducted in patients with metastatic disease in the lower limb. Receiver Operator Characteristic curves were used to identify the optimum threshold level of single stance weight bearing to predict fracture and compared to the Mirels score. Patients who underwent surgery could weight bear significantly less than those who did not have surgical intervention. The optimum threshold to predict pathological fracture was 85% of total body weight. No patient below the threshold level of 85% single stance body weight sustained a pathological fracture. The use of single stance body weight can be a useful in conjunction with the Mirels score to predict pathological fracture. If less than 85% of total body weight can be put through the affected limb, the risk of fracture increases, and consideration of treatment is suggested.

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Modeling the Population Dynamics and Economics of Velvetleaf (Abutilon theophrasti) Control in a Corn (Zea mays)-Soybean (Glycine max) Rotation

Weed Science ◽

10.1017/s0043174500081169 ◽

1995 ◽

Vol 43 (2) ◽

pp. 269-275 ◽

Cited By ~ 17

Author(s):

John L. Lindquist ◽

Bruce D. Maxwell ◽

Douglas D. Buhler ◽

Jeffrey L. Gunsolus

Keyword(s):

Population Dynamics ◽

Weed Management ◽

Management Practices ◽

Seedling Emergence ◽

Management Strategies ◽

Parameter Estimates ◽

Economic Returns ◽

Net Return ◽

Herbicide Use ◽

Optimum Threshold

A simulation model was developed to predict the population dynamics and economics of velvetleaf control in a corn-soybean rotation. Data compiled from the literature were used to parameterize the model for two situations, one in which velvetleaf was infected by aVerticilliumspp. wilt and one without infection.Verticilliumwas assumed to have no effect on corn or soybean yield. In the absence of control, simulated seedbank densities of aVerticillium-infected velvetleaf population were 5 to 50 times lower than for an uninfected velvetleaf population. The model was used to evaluate a threshold weed management strategy under the assumption that velvetleaf was the only weed and bentazon the only herbicide available for its control. In the absence ofVerticillium, an economic optimum threshold of 2.5 seedlings 100 m−2afforded the highest economic returns after 20 yr of simulation. Simulations in which velvetleaf was infected in 8 out of 20 randomly assigned years indicated a 6% increase in annualized net return and an 11 % reduction in the number of years that control was necessary. Sensitivity analysis indicated the parameter estimates having the greatest impact on economic optimum threshold were seedling emergence and survival, maximum seed production, and herbicide efficacy. Under an economic optimum threshold of 2.5 seedlings 100 m−2, management practices that manipulate the most sensitive demographic processes increased annualized net return by up to 13% and reduced long-term herbicide use by up to 26%. Results demonstrate that combining an economic optimum threshold with alternative weed management strategies may increase economic return and reduce herbicide use.

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