scholarly journals Validation of a novel functional test for assessing metamorphopsia using epiretinal membranes as a model

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Henrietta Wang ◽  
Sieu K. Khuu ◽  
Sheila Lam ◽  
Clarissa Lin ◽  
Michael Kalloniatis ◽  
...  
Keyword(s):  
Functional Test ◽  
Proof Of Concept ◽  
Step Size ◽  
Macular Disease ◽  
Epiretinal Membranes ◽  
One Step ◽  
Amsler Grid ◽  
Spatial Redundancy ◽  
Asymptomatic Disease ◽  
Psychophysical Test

Abstract Current tests for assessing metamorphopsia do not account for confounders such as perceptual filling-in and spatial redundancy, which affect its sensitivity and repeatability. This proof-of-concept study aimed to assess the performance of a novel laboratory-based psychophysical test (Line Sag Test, LST) which addresses these issues for quantification of metamorphopsia in idiopathic epiretinal membranes. The LST quantifies perpendicular metamorphopsia at three eccentricities (3°, 6°, and 9°) along eight meridians (45° steps). Metamorphopsia was assessed using the LST and Amsler grid and the hit rates of both tests for detecting metamorphopsia were compared. Normal metamorphopsia scores using the LST did not differ significantly from 0 and fell within one step-size (p = 0.500). The LST detected significantly more cases of metamorphopsia than the Amsler grid (14/21 versus 3/21) (p = 0.003). Similarly, significantly more cases of visual distortions in asymptomatic iERMs were detected using the LST than the Amsler grid (11/18 versus 0/18) (p = 0.008). The LST has a higher hit rate compared to the Amsler grid (67% versus 14%). This work demonstrates a psychophysically-robust functional test addressing perceptual confounders is more sensitive for quantifying and localising metamorphopsia in macular disease, particularly in asymptomatic disease.

Direct freezing of whole blood enables analysis of leucocyte markers by flow cytometry: a proof-of-concept study

2021 ◽  
Author(s):  
Pénélope Bourgoin ◽  
Inès Ait Belkacem ◽  
Isabelle Arnoux ◽  
Pierre-Emmanuel Morange ◽  
Fabrice Malergue
Keyword(s):  
Flow Cytometry ◽  
Whole Blood ◽  
Blood Cells ◽  
White Blood Cells ◽  
Proof Of Concept ◽  
Fresh Blood ◽  
Blood Samples ◽  
Step Flow ◽  
Freezing Method ◽  
One Step

Aim: A new one-step flow cytometry procedure has been recently demonstrated for identifying subjects with infections, but only for fresh whole blood samples. The goal of this study was to assess its applicability on frozen samples, by proposing a new method to perform the sample freezing directly and easily. Methods: Fresh blood was tested, then frozen either directly or with dimethylsulfoxide and serum. Common markers of white blood cells as well as infection-related biomarkers were tested. Results: All percentages of leucocyte subsets and levels of infection-related biomarkers were significantly correlated between frozen and fresh samples. Conclusion: The direct freezing method enables an accurate assessment of common cellular sub-populations and of levels of important infectious biomarkers via flow cytometry.

THE FORWARD MAGNETOTELLURIC PROBLEM FOR AN INHOMOGENEOUS AND ANISOTROPIC STRUCTURE

Geophysics ◽  
1974 ◽  
Vol 39 (1) ◽  
pp. 56-68 ◽  
Author(s):  
Flavian Abramovici
Keyword(s):  
Three Dimensional ◽  
Middle Layer ◽  
Conductivity Tensor ◽  
Dimensional Structure ◽  
Impedance Tensor ◽  
Variable Step Size ◽  
Step Size ◽  
Variable Step ◽  
One Step ◽  
Numerical Integration Procedure

The impedance tensor corresponding to the magnetotelluric field for a nonisotropic one‐dimensional structure is given in terms of the solutions of a sixth‐order differential system. The conductivity tensor is three‐dimensional. Its components depend upon depth only in an arbitrary manner such that the corresponding matrix is positive definite. The impedance tensor components are found by a numerical integration procedure based on a set of one‐step methods and a variable step‐size to insure a given accuracy in the final result. Calculations were made for three models having sharp boundaries and also transitional layers. The first of these models has a middle layer of high conductivity, sandwiched between two layers of linearly varying conductivity, while in the second model the middle layer has a very low conductivity. In the third model the conductivity tensor is three‐dimensional and is linearly varying in one of the layers.

scholarly journals Accelerated Runge-Kutta Methods

2008 ◽  
Vol 2008 ◽  
pp. 1-38 ◽  
Author(s):  
Firdaus E. Udwadia ◽  
Artin Farahani
Keyword(s):  
Computationally Efficient ◽  
Step Size ◽  
Time Step ◽  
Integration Schemes ◽  
Local Accuracy ◽  
Numerical Integrators ◽  
One Step ◽  
Runge Kutta ◽  
Finite Step ◽  
Proof Of Convergence

Standard Runge-Kutta methods are explicit, one-step, and generally constant step-size numerical integrators for the solution of initial value problems. Such integration schemes of orders 3, 4, and 5 require 3, 4, and 6 function evaluations per time step of integration, respectively. In this paper, we propose a set of simple, explicit, and constant step-size Accerelated-Runge-Kutta methods that are two-step in nature. For orders 3, 4, and 5, they require only 2, 3, and 5 function evaluations per time step, respectively. Therefore, they are more computationally efficient at achieving the same order of local accuracy. We present here the derivation and optimization of these accelerated integration methods. We include the proof of convergence and stability under certain conditions as well as stability regions for finite step sizes. Several numerical examples are provided to illustrate the accuracy, stability, and efficiency of the proposed methods in comparison with standard Runge-Kutta methods.

A New Hybrid Algorithm of Trust Region Methods

2014 ◽  
Vol 680 ◽  
pp. 442-446
Author(s):  
De Qing Zhang ◽  
Pei Pei Zhou ◽  
Qing Hua Zhou
Keyword(s):  
Numerical Experiments ◽  
Trust Region ◽  
Acute Angle ◽  
Step Size ◽  
Interaction Point ◽  
Trust Region Algorithms ◽  
Value Range ◽  
One Step ◽  
Current Interaction ◽  
Negative Gradient

In the solution of trust region subproblem within the classical trust region algorithms, the centre of sphere is the current interaction point and one step-size is the upper bound. Considering that only with the negative gradient direction to acute angle may reduce the function value, we introduce the parameter to control of the centre of sphere and the radius. Based on the numerical experiments, obtains the value range of the parameter. The numerical evaluation demonstrates the validity of the new trust region algorithms.

scholarly journals The community consultation process leading to the compilation of the 23 Unsolved Problems in Hydrology (UPH)

2020 ◽  
Author(s):  
Christophe Cudennec ◽  
Berit Arheimer ◽  
Günter Blöschl ◽  
Maria Helena Ramos ◽  
Elena Toth
Keyword(s):  
Working Group ◽  
International Association ◽  
Synthesis Process ◽  
Proof Of Concept ◽  
Research Subjects ◽  
Consultation Process ◽  
University Of Technology ◽  
One Step ◽  
Science Symposium ◽  
Small Working

<p>This contribution summarizes the steps of, and experiences with, a wide consultation process, led by the International Association of Hydrological Sciences (IAHS) that resulted in a list of 23 major unsolved scientific problems (UPH) in hydrology.</p><p>Step 1) Launch of a YouTube video, outlining the purpose of the initiative and its vision.</p><p>Step 2) Discussion via a LinkedIn group leading to a total of about 200 contributions and responses.</p><p>Steps 3-4) Two ‘in-person’ meetings organised in April 2019 in Vienna: one (Step 3) at the EGU General Assembly (attended by about 60 scientists), in order to solicit additional questions, at the end of which about 260 candidate problems had been compiled; the second one (Step 4) at the Vienna Catchment Science Symposium (VCSS) at the Vienna University of Technology (attended by about 110 scientists), to sort, merge, split, reword and prioritise the proposed questions. Through an iteration of parallel sessions (repeated twice, mixing the participants) and a final plenary voting session, a list of 16 ‘gold‘ and 29 ‘silver‘ questions was identified.</p><p>Step 5) Synthesis carried out by a small working group, involving representatives and members of IAHS, IAH, EGU and AGU, to consolidate, interpret and synthesise the questions, as well as to address potential biases in their selection that might have arisen from the composition of the participants at the meetings. The working group also pooled the questions into seven themes for clarity and communication. As a result of the synthesis process, the working group finally listed a set of 23 questions, presented in a community paper with over 200 authors (Blöschl et al., 2019, https://doi.org/10.1080/02626667.2019.1620507).</p><p>The UPH initiative is a proof of concept that this kind of broad consultation process is actually feasible, and is well received by the hydrological scientific community. Thus, equally important as the final list, is the community-level learning process of such a consultation, involving a large number of hydrologists and the four main learned societies in the field.</p><p>Consultations such as this could and should be repeated in the future for the benefit of our discipline, since providing common research subjects will increase the coherence of the scientific process in hydrology and promote the co-building of scientific strategies and synergy towards accelerated progress in hydrological sciences and applications.</p><p>This PICO presentation gives a short overview of the consultation process and of each of the 23 questions, shares the experiences from the process and proposes some possible future steps.</p>

scholarly journals Overhead Line Mechanics Taking the Influence of Wind into Account

10.14311/1642 ◽  
2012 ◽  
Vol 52 (5) ◽  
Author(s):  
Miroslav Müller
Keyword(s):  
Harmonic Component ◽  
Overhead Line ◽  
Step Size ◽  
Continuous Description ◽  
Spatial Coordinates ◽  
One Step ◽  
Catenary Curve ◽  
Harmonic Components ◽  
Dynamic Description ◽  
The Time Domain

This paper deals with problems of overhead line motion. The line model is based on a dynamic description of a catenary curve. The benefits of dynamic modeling in this field are decrypted, and there is an explanation of one of the models that is used. The dynamic model is derived from a string equation. The main contribution of the model is in 3D simulation of complex mechanics. The model of an overhead line shaking is generally based on the superposition of harmonic components, in particular the spatial coordinates. Each individual harmonic component is solved separately in one step of calculation, and is then combined with the other solutions. The result is a continuous description of the position of the wire along its length in both the space domain and the time domain. The model thus allows calculationsof uneven effects of forces along the length of an overhead line. The accuracy of the calculation is determined by the number of harmonics and other parameters that are calculated (e.g. step size, simulation time) The model is actually a combination of discrete and continuous calculations. Each model function block is described in the form of an equation. In the case study, ACSR 350/59 wire is analyzed. In this part of our work, an auxiliary model of wind influence was integrated into the global model.

scholarly journals Making pointer analysis more precise by unleashing the power of selective context sensitivity

2021 ◽  
Vol 5 (OOPSLA) ◽  
pp. 1-27
Author(s):  
Tian Tan ◽  
Yue Li ◽  
Xiaoxing Ma ◽  
Chang Xu ◽  
Yannis Smaragdakis
Keyword(s):  
State Of The Art ◽  
Context Sensitivity ◽  
The State ◽  
Pointer Analysis ◽  
Proof Of Concept ◽  
Context Sensitive ◽  
Java Programs ◽  
One Step ◽  
The Difference

Traditional context-sensitive pointer analysis is hard to scale for large and complex Java programs. To address this issue, a series of selective context-sensitivity approaches have been proposed and exhibit promising results. In this work, we move one step further towards producing highly-precise pointer analyses for hard-to-analyze Java programs by presenting the Unity-Relay framework, which takes selective context sensitivity to the next level. Briefly, Unity-Relay is a one-two punch: given a set of different selective context-sensitivity approaches, say S = S1, . . . , Sn, Unity-Relay first provides a mechanism (called Unity)to combine and maximize the precision of all components of S. When Unity fails to scale, Unity-Relay offers a scheme (called Relay) to pass and accumulate the precision from one approach Si in S to the next, Si+1, leading to an analysis that is more precise than all approaches in S. As a proof-of-concept, we instantiate Unity-Relay into a tool called Baton and extensively evaluate it on a set of hard-to-analyze Java programs, using general precision metrics and popular clients. Compared with the state of the art, Baton achieves the best precision for all metrics and clients for all evaluated programs. The difference in precision is often dramatic — up to 71% of alias pairs reported by previously-best algorithms are found to be spurious and eliminated.

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