Numerical-statistical study of the prognostic efficiency of the SEIR model

2021 ◽  
Vol 36 (6) ◽  
pp. 337-345
Author(s):  
Galiya Z. Lotova ◽  
Vitaliy L. Lukinov ◽  
Mikhail A. Marchenko ◽  
Guennady A. Mikhailov ◽  
Dmitrii D. Smirnov
Keyword(s):  
Comparative Analysis ◽  
Test Problem ◽  
Statistical Study ◽  
Poisson Model ◽  
Time Interval ◽  
Initial Population ◽  
Statistical Average ◽  
Confidential Interval ◽  
Seir Model ◽  
Statistical Estimates

Abstract A comparative analysis of the differential and the corresponding stochastic Poisson SEIR-models is performed for the test problem of COVID-19 epidemic in Novosibirsk modelling the period from March 23, 2020 to June 21, 2020 with the initial population N = 2 798 170. Varying the initial population in the form N = n m with m ⩾ 2, we show that the average numbers of identified sick patients is less (beginning from April 7, 2020) than the corresponding differential values by the quantity that does not differ statistically from C(t)/m, with C ≈ 27.3 on June 21, 2020. This relationship allows us to use the stochastic model for big population N. The practically useful ‘two sigma’ confidential interval for the time interval from June 1, 2020 to June 21, 2020 is about 108% (as to the statistical average) and involves the corresponding real statistical estimates. The influence of the introduction of delay on the prognosis, i.e., the incubation period corresponding to Poisson model is also studied.

scholarly journals 8806 Russian patients demonstrate T cell count as better marker of COVID-19 clinical course severity than SARS-CoV-2 viral load

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Konstantin S. Sharov
Keyword(s):  
Viral Load ◽  
Comparative Analysis ◽  
T Cell ◽  
Cell Count ◽  
T Lymphocyte ◽  
Clinical Course ◽  
Time Interval ◽  
Early Prediction ◽  
Disease Prognosis ◽  
Respiratory Index

AbstractThe article presents a comparative analysis of SARS-CoV-2 viral load (VL), T lymphocyte count and respiratory index PaO2:FiO2 ratio as prospective markers of COVID-19 course severity and prognosis. 8806 patients and asymptomatic carriers were investigated in time interval 15 March–19 December 2020. T cell count demonstrated better applicability as a marker of aggravating COVID-19 clinical course and unfavourable disease prognosis than SARS-CoV-2 VL or PaO2:FiO2 ratio taken alone. Using T cell count in clinical practice may provide an opportunity of early prediction of deteriorating a patient’s state.

scholarly journals A theoretical framework for multi-species range expansion in spatially heterogeneous landscapes

2021 ◽  
Author(s):  
Lukas Eigentler ◽  
Nicola R Stanley-Wall ◽  
Fordyce A Davidson
Keyword(s):  
Population Density ◽  
Range Expansion ◽  
Theoretical Framework ◽  
Dominant Mode ◽  
Bacterial Biofilm ◽  
Time Interval ◽  
Initial Population ◽  
Initial Population Density ◽  
Competitive Outcome ◽  
The Impact

Range expansion is the spatial spread of a population into previously unoccupied regions. Understanding range expansion is important for the study and successful manipulation and management of ecosystems, with applications ranging from controlling bacterial biofilm formation in industrial and medical environments to large scale conservation programmes for species undergoing climate-change induced habitat disruption. During range expansion, species typically encounter competitors. Moreover, the environment into which expansion takes place is almost always heterogeneous when considered at the scale of the individual. Despite the ubiquitous nature of these features, the impact of competition and spatial landscape heterogeneities on range expansion remains understudied. In this paper we present a theoretical framework comprising two competing generic species undergoing range expansion and use it to investigate the impact of spatial landscape heterogeneities on range expansion with a particular focus on its effect on competition dynamics. We reveal that the area covered by range expansion during a fixed time interval is highly variable due to the fixed landscape heterogeneities. Moreover, we report significant variability in competitive outcome (relative abundance of a focal species) but determine that this is induced by low initial population densities, independent of landscape heterogeneities. We further show that both area covered by range expansion and competitive outcome can be accurately predicted by a Voronoi tessellation with respect to an appropriate metric, which only requires information on the spatial landscape and the response of each species to that landscape. Finally, we reveal that if species interact antagonistically during range expansion, the dominant mode of competition depends on the initial population density. Antagonistic actions determine competitive outcome if the initial population density is high, but competition for space is the dominant mode of competition if the initial population density is low.

Comparative Analysis of the Results of Coronavirus Imaging on PEM and SPM

2020 ◽  
Vol 22 (9) ◽  
pp. 516-522
Author(s):  
L.Zh. Shugunov ◽  
◽  
T.L. Shugunov ◽  
Keyword(s):  
Comparative Analysis ◽  
Test Problem ◽  
Size Range ◽  
Practical Interest ◽  
Scanning Probe Microscope ◽  
Scanning Probe ◽  
Probe Microscope ◽  
Mathematical Processing

This paper presents the results of research and comparison of the image of the coronavirus obtained on PEM with the results of processing using a scanning probe microscope in AFM mode. It is known that in this size range, fairly accurate results can be obtained on SPM devices, followed by mathematical processing, which is of scientific and practical interest, which is also important for medicine. In addition, the study of processes-objects using various independent methods allows you to get more reliable results, in this paper, to obtain more reliable results of the values of the characteristics-parameters of the coronavirus. The results of a test problem study are also given to illustrate the method's performance.

scholarly journals Media Representation of Muslim Women in ‘Time’ & ‘Newsweek’: A Comparative Analysis within Feministic Perspective

2021 ◽  
Vol volume 05 (issue 2) ◽  
pp. 61-72
Author(s):  
Zaheer-Ud-Din Babar ◽  
Sadaf Zahra ◽  
Tahreem Nasir
Keyword(s):  
Comparative Analysis ◽  
Research Study ◽  
Muslim Women ◽  
Statistical Test ◽  
Media Representation ◽  
Time Interval ◽  
Z Score ◽  
News Magazines ◽  
Time Period ◽  
Different Dimensions

This research study patently aims to examine media representation of Muslim Women within Feministic perspective by analyzing its content published in ‘Time’ and ‘Newsweek’ during the selected time period of 2011 – 2013. One of the main objectives of this study is to dig out the prevailing differences within overall coverage of both news magazines regarding the Muslim women. These differences are further studied in four different dimensions i.e. categories, slants, tones and themes. Basically, this is a census study (as the collected data was limited) where content analysis has been used as research methodology. Whereas, Z-score statistical test is applied for the analysis. In results, study reveals that there are slight differences between the way both magazines present the Muslim women. Both news magazines mainly highlight ‘Progressive women’ favorably; discuss Islam negatively; and Social Status of the Muslim women has mainly been highlighted throughout the designated time interval.

scholarly journals Construction of a model of evolution of objects of small-sized fraction of space debris formed as a result of destruction

2021 ◽  
pp. 1-27
Author(s):  
Gennady Konstantinovich Borovin ◽  
Mikhail Vitalyevich Zakhvatkin ◽  
Victor Arkadievich Stepaniants ◽  
Igor Vyacheslavovich Usovik
Keyword(s):  
Space Debris ◽  
Time Interval ◽  
System Of Equations ◽  
Mass Ratio ◽  
Space Object ◽  
Earth Space ◽  
Near Earth Space ◽  
Statistical Estimates ◽  
Long Time ◽  
Common Understanding

The paper proposes a approach for constructing a statistical model for the distribution of a small-sized fraction of space debris in near-earth space, based on a particular model of the evolution of objects of a small-sized fraction of space debris. An algorithm for predicting the evolution of objects of small-sized fraction of space debris formed as a result of the destruction of the parent space object over a long time interval is described, as well as a system of equations in variations for mass calculations and statistical estimates of the parameters of the distribution of space debris in near-earth space. At a time interval of 10 years, calculations were carried out to obtain a common understanding of the evolution and lifetime of fragments of space debris ranging in size from 0.01 to 1 mm in the orbits of real groups and individual spacecraft. The time of existence of objects of small-sized fraction of space debris of the specified sizes depending on the parameters of the orbit and the value of their area-to-mass ratio is determined.

scholarly journals COMPARATIVE ANALYSIS OF STEEL CORROSION RESISTANCE

2020 ◽  
Vol 1 (2) ◽  
pp. 12-17
Author(s):  
Chao Zhang ◽  
Xiang Yin ◽  
Chun Qing
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Comparative Analysis ◽  
Carbon Steel ◽  
Salt Spray ◽  
Steel Corrosion ◽  
Immersion Test ◽  
Time Interval ◽  
Regular Time ◽  
Threshold Ratio

The objective of the study was to conduct the comparative analysis of steel types corrosion resistance. Three selected steel types were used in the study. The selected types were structural steel, stainless steel, and MMFX steel. The methodology we adopted is that we evaluated the steel parts resistance towards corrosion by doing in-salt spray experiment and the immersion of aqueous solution of sodium chloride. For salt spray test, we used guidelines by ASTM B117. This practice provides a controlled corrosion environment which is used for exposing specimen to salt spray chamber. For immersion test, test specimens are analyzed at regular time interval as the first rust is appeared. For carbon steel, we used three specimen and mostly initial rust appeared in initial 13 to 15 hours. For stainless steel, inter granular corrosion were analyzed. The results show that the first cycle started after about 46 hours; the second cycle started about 1% and the third cycle started with the rage of about 2 to 30%. For MMFX 2 steel, the results show that for MMFX carbon steel, the chloride threshold ratio is about 6 times higher than black bars and more than double of other types. The conclusion of the study is that in big structures like bridges, the MMFX steel should be used.

Estimation of the derivative of a stationary measure with respect to a control parameter

1992 ◽  
Vol 29 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Felisa J. Vázquez-Abad ◽  
Harold J. Kushner
Keyword(s):  
Monte Carlo ◽  
Sequential Monte Carlo ◽  
Transition Probability ◽  
Transition Function ◽  
Stationary Measure ◽  
Time Interval ◽  
Monte Carlo Optimization ◽  
Statistical Estimates ◽  
Approximating Sequence ◽  
Step Transition

The paper deals with a problem which arises in the Monte Carlo optimization of steady state or ergodic systems which can be modelled by Markov chains. The transition probability depends on a parameter, and one wishes to find the parameter value at which some performance function is minimum. The only available data are obtained from either simulation or actual operating information. For such a problem one needs good statistical estimates of the derivatives. Conditions are given for the existence of the derivative of the stationary measure with respect to the parameter, in the sense that the derivative is a signed measure, and is the limit of the natural approximating sequence. Some properties and a useful characterization of the derivative are obtained. It is also shown that, under appropriate conditions, the derivative of the n-step transition function converges to the derivative of the stationary measure as n tends to ∞. This latter result is of particular importance whether one is simply estimating or is actually optimizing via some sequential Monte Carlo procedure, since the basic observations are always taken over a finite time interval.

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