scholarly journals Integrated framework for rapid climate stress testing on a monthly timestep

2021 ◽  
Author(s):  
Keirnan Fowler ◽  
Natasha Ballis ◽  
Avril Horne ◽  
Andrew John ◽  
Rory Nathan ◽  
...  
Keyword(s):  
Water Resource ◽  
Stress Testing ◽  
Stress Test ◽  
Low Frequency ◽  
Frequency Component ◽  
Water Resource System ◽  
Climate Stress ◽  
Delta Change ◽  
Large Water ◽  
Carry Over

“Bottom-up” methods are increasingly used to assess the vulnerability of water systems to climate change. Central to these methods is the climate “stress test”, where the system is subjected to various climatic changes to test for unacceptable outcomes. We present a framework for climate stress testing on a monthly timestep, suitable for systems whose dominant dynamic is seasonal or longer (eg. water resource systems with carry-over storage). The framework integrates multi-site stochastic climate generation with perturbation methods and in-built rainfall runoff modelling. The stochastic generation includes a low frequency component suitable for representing multi-annual fluctuations. Multiple perturbation options are provided, ranging from simple delta change through to altered seasonality and low frequency dynamics. The framework runs rapidly, supporting comprehensive multi-dimensional stress testing without recourse to supercomputing facilities. We demonstrate the framework on a large water resource system in southern Australia. The Matlab/Octave framework is freely available for download from https://doi.org/10.5281/zenodo.5617008.

Stress-testing Russian Banking System: Will Banks Need Government Assistance Again?

2010 ◽  
pp. 61-81 ◽  
Author(s):  
O. Solntsev ◽  
A. Pestova ◽  
M. Mamonov
Keyword(s):  
Stress Testing ◽  
Banking Sector ◽  
Stress Test ◽  
Banking System ◽  
Government Assistance ◽  
Methodological Issues ◽  
Loan Portfolio ◽  
Macroeconomic Indicators ◽  
Remote Stress ◽  
Capital Injections

The article analyzes factors that affect growth of the share of non-performing loans in the loan portfolio of Russian banks and proposes approaches for this share forecasting on the basis of dynamics of macroeconomic indicators. It also deals with methodological issues of remote stress-test of lending agencies. Using the results of conducted stress-test of Russian banks the authors assess their perspective capital needs in 2010 and estimate the share of government assistance in capital injections. Furthermore, the authors define the scale of vulnerable banks groups in the Russian banking sector.

scholarly journals Quality control stress test for deep learning-based diagnostic model in digital pathology

2021 ◽  
Author(s):  
Birgid Schömig-Markiefka ◽  
Alexey Pryalukhin ◽  
Wolfgang Hulla ◽  
Andrey Bychkov ◽  
Junya Fukuoka ◽  
...  
Keyword(s):  
Deep Learning ◽  
Cancer Detection ◽  
Stress Testing ◽  
Computational Analysis ◽  
Stress Test ◽  
Digital Pathology ◽  
Model Performance ◽  
Diagnostic Model ◽  
Model Accuracy ◽  
Diagnostic Models

AbstractDigital pathology provides a possibility for computational analysis of histological slides and automatization of routine pathological tasks. Histological slides are very heterogeneous concerning staining, sections’ thickness, and artifacts arising during tissue processing, cutting, staining, and digitization. In this study, we digitally reproduce major types of artifacts. Using six datasets from four different institutions digitized by different scanner systems, we systematically explore artifacts’ influence on the accuracy of the pre-trained, validated, deep learning-based model for prostate cancer detection in histological slides. We provide evidence that any histological artifact dependent on severity can lead to a substantial loss in model performance. Strategies for the prevention of diagnostic model accuracy losses in the context of artifacts are warranted. Stress-testing of diagnostic models using synthetically generated artifacts might be an essential step during clinical validation of deep learning-based algorithms.

scholarly journals A novel method of quantifying hemodynamic delays to improve hemodynamic response, and CVR estimates in CO2 challenge fMRI

2021 ◽  
pp. 0271678X2097858
Author(s):  
Jinxia (Fiona) Yao ◽  
Ho-Ching (Shawn) Yang ◽  
James H Wang ◽  
Zhenhu Liang ◽  
Thomas M Talavage ◽  
...  
Keyword(s):  
Arrival Time ◽  
Stress Test ◽  
Low Frequency ◽  
Hemodynamic Response ◽  
Blood Oxygen Level Dependent ◽  
Cerebrovascular Reactivity ◽  
Bold Signal ◽  
Hemodynamic Response Function ◽  
Carbon Dioxide Co2 ◽  
Co2 Challenge

Elevated carbon dioxide (CO2) in breathing air is widely used as a vasoactive stimulus to assess cerebrovascular functions under hypercapnia (i.e., “stress test” for the brain). Blood-oxygen-level-dependent (BOLD) is a contrast mechanism used in functional magnetic resonance imaging (fMRI). BOLD is used to study CO2-induced cerebrovascular reactivity (CVR), which is defined as the voxel-wise percentage BOLD signal change per mmHg change in the arterial partial pressure of CO2 (PaCO2). Besides the CVR, two additional important parameters reflecting the cerebrovascular functions are the arrival time of arterial CO2 at each voxel, and the waveform of the local BOLD signal. In this study, we developed a novel analytical method to accurately calculate the arrival time of elevated CO2 at each voxel using the systemic low frequency oscillations (sLFO: 0.01-0.1 Hz) extracted from the CO2 challenge data. In addition, 26 candidate hemodynamic response functions (HRF) were used to quantitatively describe the temporal brain reactions to a CO2 stimulus. We demonstrated that our approach improved the traditional method by allowing us to accurately map three perfusion-related parameters: the relative arrival time of blood, the hemodynamic response function, and CVR during a CO2 challenge.

The Lightning Electromagnetic Pulse Coupling Effect Inside the Shielding Enclosure With Penetrating Wire

Frequenz ◽  
2017 ◽  
Vol 71 (11-12) ◽  
Author(s):  
Xue Jiao ◽  
Bo Yang
Keyword(s):  
Electromagnetic Pulse ◽  
Coupling Effect ◽  
Fdtd Method ◽  
Current Source ◽  
Low Frequency ◽  
Frequency Component ◽  
Lightning Current ◽  
Proper Size ◽  
Practical Engineering ◽  
Difference Time

AbstractTo study the lightning electromagnetic pulse (LEMP) coupling and protection problems of shielding enclosure with penetrating wire, we adopt the model with proper size which is close to the practical engineering and the two-step finite-difference time-domain (FDTD) method is used for calculation in this paper. It is shown that the coupling voltage on the circuit lead inside the enclosure increases about 34 dB, when add 1.0 m long penetrating wire at the aperture, comparing with the case without penetrating wire. Meanwhile, the waveform, has the same wave outline as the lightning current source, shows that the penetrating wire brings a large number of low frequency component into the enclosure. The coupling effect in the enclosure will reduce greatly when penetrating wire has electrical connection with the enclosure at the aperture and the coupling voltage increase only about 12 dB than the case without penetrating wire. Moreover, the results show that though the waveguide pipe can reduce the coupling effect brought by the penetrating wire, the exposing part of penetrating wire can increase the coupling when the penetrating wire outside the enclosure is longer than the waveguide pipe and the longer the exposing part is, the stronger the coupling is.

Low-frequency component electric microfield distributions in plasmas governed by W. Ebeling potential

2021 ◽  
Author(s):  
Sara Kobbi ◽  
Salima Guerricha ◽  
Smaïl Chihi ◽  
Abdallah Bekkouche ◽  
Mohammed Tayeb Meftah
Keyword(s):  
Low Frequency ◽  
Frequency Component

Abstract 363: Chest Pain Observation Unit: Does Post-Discharge Stress Testing Influence Physician Management Decisions?

2014 ◽  
Vol 7 (suppl_1) ◽  
Author(s):  
Yasser Khalil ◽  
Martin E Matsumura ◽  
Maida Abdul-Latif ◽  
Prasant Pandey ◽  
Melvin Schwartz
Keyword(s):  
Chest Pain ◽  
Risk Stratification ◽  
Stress Testing ◽  
Stress Test ◽  
Multivariate Regression Analysis ◽  
The United States ◽  
Observation Unit ◽  
Management Decisions ◽  
Post Discharge ◽  
Effective Manner

Background: Chest pain (CP) accounts for approximately 6 million emergency visits per year in the United States. There is growing interest in strategies to effectively risk stratify pts for coronary artery disease (CAD) related events in a cost-effective manner. The use of chest pain observation units followed by early stress testing is frequently employed in these pts. However the utility of stress testing in this population is not well defined, and the effect of stress test results on subsequent management decisions is a topic of controversy. In the present study we examined the relationship of stress myocardial perfusion imaging (MPI) results to physician decisions regarding ccath in a single community teaching hospital. Methods: Retrospective study of 426 pts undergoing a chest pain observation strategy over a 24 month period. Pt eligible for the program had CP deemed possibly related to CAD but no diagnostic ECG changes and negative TnI measurements x2. All pts underwent outpt. stress MPI within 72 hours of discharge. Pts saw a cardiologist the day of stress MPI who reviewed the CP history, MPI results, and made decisions regarding further risk stratification. Demographic and medical history was collected from the pts chest pain observation unit record. Multivariate regression analysis was used to determine significant independent variables related to physician decisions regarding further risk stratification. Results: Of 426 pts who underwent outpt stress MPI, 71(16.7%) were positive for ischemia, and 16 (22.5% of +MPI) underwent cath with reperfusion performed in 8 (5PCI, 3 CABG, 11.3% of +MPI). Of the 355 pts with negative stress MPI, 5(1.4% of -MPI) underwent cath with reperfusion performed in 2 (2PCI, 0 CABG, 0.5% of -MPI). A MLR model suggested only stress MPI results were independently predictive of the use of ccath for risk stratification. Conclusion: Stress MPI was an important factor in physician decision-making regarding the need for ccath in pts managed in a chest pain observation unit. The rate of +MPI and subsequent use of ccath in our institution supports MPI as an appropriate step in risk stratification of low to moderate risk CP pts triaged through a CP observation unit.

scholarly journals Comparison of Preoperative Assessment of Patient’s Metabolic Equivalents (METs) Estimated from History versus Measured by Exercise Cardiac Stress Testing

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Adam S. Weinstein ◽  
Martin I. Sigurdsson ◽  
Angela M. Bader
Keyword(s):  
Cardiac Failure ◽  
Stress Testing ◽  
Stress Test ◽  
Preoperative Evaluation ◽  
Preoperative Assessment ◽  
Exercise Stress ◽  
Cardiac Stress ◽  
Metabolic Equivalents ◽  
Cardiac Stress Testing ◽  
Cardiac Stress Test

Background. Preoperative anesthetic evaluations of patients before surgery traditionally involves assessment of a patient’s functional capacity to estimate perioperative risk of cardiovascular complications and need for further workup. This is typically done by inquiring about the patient’s physical activity, with the goal of providing an estimate of the metabolic equivalents (METs) that the patient can perform without signs of myocardial ischemia or cardiac failure. We sought to compare estimates of patients’ METs between preoperative assessment by medical history with quantified assessment of METs via the exercise cardiac stress test. Methods. A single-center retrospective chart review from 12/1/2005 to 5/31/2015 was performed on 492 patients who had preoperative evaluations with a cardiac stress test ordered by a perioperative anesthesiologist. Of those, a total of 170 charts were identified as having a preoperative evaluation note and an exercise cardiac stress test. The METs of the patient estimated by history and the METs quantified by the exercise cardiac stress test were compared using a Bland–Altman plot and Cohen’s kappa. Results. Exercise cardiac stress test quantified METs were on average 3.3 METS higher than the METs estimated by the preoperative evaluation history. Only 9% of patients had lower METs quantified by the cardiac stress test than by history. Conclusions. The METs of a patient estimated by preoperative history often underestimates the METs measured by exercise stress testing. This demonstrates that the preoperative assessments of patients’ METs are often conservative which errs on the side of patient safety as it lowers the threshold for deciding to order further cardiac stress testing for screening for ischemia or cardiac failure.

scholarly journals Electron acoustic solitons in the Earth's magnetotail

2004 ◽  
Vol 11 (2) ◽  
pp. 215-218 ◽  
Author(s):  
S. G. Tagare ◽  
S. V. Singh ◽  
R. V. Reddy ◽  
G. S. Lakhina
Keyword(s):  
Electron Beam ◽  
Small Amplitude ◽  
Low Frequency ◽  
Frequency Component ◽  
Magnetized Plasma ◽  
Cold Electron ◽  
Ion Plasma ◽  
Electron Acoustic ◽  
Two Temperature ◽  
Perpendicular Polarization

Abstract. Small amplitude electron - acoustic solitons are studied in a magnetized plasma consisting of two types of electrons, namely cold electron beam and background plasma electrons and two temperature ion plasma. The analysis predicts rarefactive solitons. The model may provide a possible explanation for the perpendicular polarization of the low-frequency component of the broadband electrostatic noise observed in the Earth's magnetotail.

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