scholarly journals Descriptive understanding and prediction in COVID-19 modelling

2021 ◽  
Vol 43 (4) ◽  
Author(s):  
Johannes Findl ◽  
Javier Suárez
Keyword(s):  
Curve Fitting ◽  
Statistical Models ◽  
Philosophical Question ◽  
Epidemiological Models ◽  
Causal Knowledge ◽  
Predictive Capacity ◽  
Main Form ◽  
The Relationship ◽  
In Virtue Of ◽  
Political Decisions

AbstractCOVID-19 has substantially affected our lives during 2020. Since its beginning, several epidemiological models have been developed to investigate the specific dynamics of the disease. Early COVID-19 epidemiological models were purely statistical, based on a curve-fitting approach, and did not include causal knowledge about the disease. Yet, these models had predictive capacity; thus they were used to ground important political decisions, in virtue of the understanding of the dynamics of the pandemic that they offered. This raises a philosophical question about how purely statistical models can yield understanding, and if so, what the relationship between prediction and understanding in these models is. Drawing on the model that was developed by the Institute of Health Metrics and Evaluation, we argue that early epidemiological models yielded a modality of understanding that we call descriptive understanding, which contrasts with the so-called explanatory understanding which is assumed to be the main form of scientific understanding. We spell out the exact details of how descriptive understanding works, and efficiently yields understanding of the phenomena. Finally, we vindicate the necessity of studying other modalities of understanding that go beyond the conventionally assumed explanatory understanding.

scholarly journals Does Revitalizing the Center of Mid-Sized French Cities Reduce GHG Emissions from Commuting?

2021 ◽  
Vol 13 (4) ◽  
pp. 1851
Author(s):  
Alexis Poulhès ◽  
Angèle Brachet
Keyword(s):  
Land Use Planning ◽  
Statistical Models ◽  
Total Population ◽  
Ghg Emissions ◽  
Low Carbon ◽  
Trip Distance ◽  
Working People ◽  
Shrinking City ◽  
The Relationship ◽  
Positive Effect

Mid-sized cities are usually considered in the literature to be shrinking cities. Some policies promote right-sizing and others promote revitalization. The relationship between land-use planning and mobility having been established, the present research issue is focused on whether a policy of revitalizing the centers of mid-sized cities is favorable to low-carbon mobility. Our study investigates commuting trips through two indicators: commuting trip distance and car modal share. The increase in total population, the increase in the number of jobs per resident, the decrease in the unemployment rate, the increase in the rate of executives, the increase in the rate of working people in the population and the decrease in the residential vacancy rate all come from the censuses of 2006 and 2016. Statistical models based on individuals in 113 mid-sized cities, in which sociodemographic variables are introduced, show that at the level of agglomerations, no indicator has a simultaneously positive effect in the center and in the urban periphery. No indicator is entirely positive or negative on GHG emissions from commuting trips. While the increase in GHG emissions from commuting trips between 2006 and 2016 is significant in mid-sized cities (18%), a shift toward shrinking city centers is insufficient to change this trajectory.

Research in Destruction of Concrete Bridge Expanded Joint Influenced by Temperature Difference

2015 ◽  
Vol 744-746 ◽  
pp. 803-806 ◽  
Author(s):  
Xiao Lei ◽  
Yue Yao ◽  
Shi Cao ◽  
Zhi Gang Guo
Keyword(s):  
Temperature Difference ◽  
Curve Fitting ◽  
Effective Temperature ◽  
Joint Damage ◽  
Measured Data ◽  
Concrete Bridge ◽  
Box Girder ◽  
Concrete Box Girder ◽  
Extremum Value ◽  
The Relationship

Destruction of bridge expanded joint is a serious problem for concrete bridge. Based on 5 years measured data, the temperature in the different positions of the concrete box girder was systemically analyzed to illuminate the cause of the bridge expanded joint damage. A method for predicting the extremum value of the temperature difference of concrete girder was proposed by use of the extrema analysis and curve fitting based on the temperature in the different positions of the concrete box girder. The relationship is quite useful in estimating the destruction of bridge expanded joint by effective temperature difference in concrete box-girder.

scholarly journals The relationship between SARS-COV-2 RNA positive duration and the risk of recurrent positive

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Hong Zhao ◽  
Chi Zhang ◽  
Xian-Xiang Chen ◽  
Qi Zhu ◽  
Wen-Xiang Huang ◽  
...  
Keyword(s):  
Curve Fitting ◽  
Additive Model ◽  
Smooth Curve ◽  
Fold Increase ◽  
Monocyte Count ◽  
Increased Risk ◽  
Adjusted Logistic Regression ◽  
Multi Center Study ◽  
Adjusted Model ◽  
The Relationship

Abstract Background The management of discharge COVID-19 patients with recurrent positive SARS-CoV-2 RNA is challenging. However, there are fewer scientific dissertations about the risk of recurrent positive. The aim of this study was to explore the relationship between SARS-COV-2 RNA positive duration (SPD) and the risk of recurrent positive. Methods This case–control multi-center study enrolled participants from 8 Chinese hospital including 411 participants (recurrent positive 241). Using unadjusted and multivariate-adjusted logistic regression analyses, generalized additive model with a smooth curve fitting, we evaluated the associations between SPD and risk of recurrent positive. Besides, subgroup analyses were performed to explore the potential interactions. Results Among recurrent positive patients, there were 121 females (50.2%), median age was 50 years old [interquartile range (IQR): 38–63]. In non-adjusted model and adjusted model, SPD was associated with an increased risk of recurrent positive (fully-adjusted model: OR = 1.05, 95% CI: 1.02–1.08, P = 0.001); the curve fitting was not significant (P = 0.286). Comparing with SPD < 14 days, the risk of recurrent positive in SPD > 28 days was risen substantially (OR = 3.09, 95% CI: 1.44–6.63, P = 0.004). Interaction and stratified analyses showed greater effect estimates of SPD and risk of recurrent positive in the hypertension, low monocyte count and percentage patients (P for interaction = 0.008, 0.002, 0.036, respectively). Conclusion SPD was associated with a higher risk of recurrent positive and especially SPD > 28 day had a two-fold increase in the relative risk of re-positive as compared with SPD < 14 day. What’s more, the risk may be higher among those with hypertension and lower monocyte count or percentage.

Statistical characterization of the random errors in the radioimmunoassay dose--response variable.

1976 ◽  
Vol 22 (3) ◽  
pp. 350-358 ◽  
Author(s):  
D Rodbard ◽  
R H Lenox ◽  
H L Wray ◽  
D Ramseth
Keyword(s):  
Least Squares ◽  
Dose Response ◽  
Curve Fitting ◽  
Response Curve ◽  
Dose Response Curve ◽  
Random Errors ◽  
Statistical Characterization ◽  
Response Variable ◽  
Least Squares Curve Fitting ◽  
The Relationship

Abstract We have developed practical methods for evaluating the magnitude of the random errors in radioimmunoassay dose--response variables, and the relationship between this error and position on the dose--response curve. This is important: to obtain appropriate weights for each point on the dose--response curve when utilizing least-squares curve-fitting methods; to evaluate whether the standards and the unknowns are subject to error of the same magnitude; for quality-control purposes; and to study the sources of errors in radioimmunoassay. Both standards and unknowns in radioimmunoassays for cAMP and cGMP were analyzed in triplicate. The same mean (Y), sample standard deviation, sy, and variance (2-y) of the response variable were calculated for each dose level. The relationship between s 2-y and y was calculated utilizing several models. Results for standards and unknowns from several assays were pooled, and a curve smoothing procedure was used to minimize random sampling errors. This pooling increased the reliability of the analysis, and confirmed the presence of the theoretically predicted nonuniformity of variance. Thus, the calculation of results from these radioimmunoassays should utilize a weighted least-squares curve-fitting program. These analyses have been computerized, and can be used as a "pre-processor" for programs for routine analysis of results of radioimmunoassay.

scholarly journals Hedging Activities Information and Risk Management Committee Effectiveness: Malaysian evidence

2018 ◽  
Author(s):  
Azrul Bin Abdullah ◽  
Ku Nor Izah Ku Ismail
Keyword(s):  
Risk Management ◽  
Corporate Governance ◽  
Significant Influence ◽  
Statistical Models ◽  
Voluntary Disclosure ◽  
Annual Reports ◽  
Management Committee ◽  
Corporate Governance Mechanisms ◽  
The Relationship ◽  
Risk Management Committee

This study examines the extent of information about hedging activities disclosures within the annual reports of Main Market companies listed on Bursa Malaysia. The extent of hedging activities disclosures is captured through a 32-item-template, which consists of a mandatory and voluntary disclosure scores. The results of this study indicate that the extent of information on hedging activities disclosure is still insufficient among the sampled companies even though the disclosure scored is quite high. This study also examines the relationship between the existence of risk management committee (RMC), its characteristics and the extent of information on hedging activities disclosure in two separate statistical models. The regression results imply that the existence of RMC is positive but does not significantly influence the extent of information on hedging activities disclosure. However its characteristics (i.e. RMC independence and RMC meeting) have a significant influence. The findings may provide some meaningful insights to regulators, policymakers and researchers, towards the establishment of RMC as a part of the internal corporate governance mechanisms. In addition to its existence, the effectiveness of RMC also needs to be emphasised.

8. Referendums

UK Politics ◽  
2021 ◽  
pp. 171-191
Author(s):  
Andrew Blick
Keyword(s):  
Direct Democracy ◽  
Local Level ◽  
The European Union ◽  
The Public ◽  
Key Features ◽  
Definition Of ◽  
The Uk ◽  
The Relationship ◽  
Theoretical Considerations ◽  
Political Decisions

This chapter starts with a definition of the term ‘referendum’. A referendum is a means of involving the public in political decisions via voting on specific issues such as leaving the European Union. The chapter focuses on the use of referendums at the local level. It sets out the key features of a referendum. Who is allowed to vote in referendums? What sort of questions are put to voters? Under want circumstances should a referendum take place on specific issues? What are the risks associated with holding a referendum? The chapter also looks at regulations surrounding referendums in the UK. The theoretical considerations that the chapter examines are the fact that a referendum subject tends to be controversial, the relationship between referendums and direct democracy and the implications of the results.

scholarly journals Continuous Evaluation of Track Modulus from a Moving Railcar Using ANN-Based Techniques

Vibration ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Ngoan T. Do ◽  
Mustafa Gül ◽  
Saeideh Fallah Nafari
Keyword(s):  
Curve Fitting ◽  
Estimation Accuracy ◽  
Promising Tool ◽  
Lower Accuracy ◽  
Track Condition ◽  
University Of Nebraska Lincoln ◽  
The University ◽  
The Relationship ◽  
Track Modulus ◽  
Different Levels

Track foundation stiffness (also referred as the track modulus) is one of the main parameters that affect the track performance, and thus, quantifying its magnitudes and variations along the track is widely accepted as a method for evaluating the track condition. In recent decades, the train-mounted vertical track deflection measurement system developed at the University of Nebraska–Lincoln (known as the MRail system) appears as a promising tool to assess track structures over long distances. Numerical methods with different levels of complexity have been proposed to simulate the MRail deflection measurements. These simulations facilitated the investigation and quantification of the relationship between the vertical deflections and the track modulus. In our previous study, finite element models (FEMs) with a stochastically varying track modulus were used for the simulation of the deflection measurements, and the relationships between the statistical properties of the track modulus and deflections were quantified over different track section lengths using curve-fitting approaches. The shortcoming is that decreasing the track section length resulted in a lower accuracy of estimations. In this study, the datasets from the same FEMs are used for the investigations, and the relationship between the measured deflection and track modulus averages and standard deviations are quantified using artificial neural networks (ANNs). Different approaches available for training the ANNs using FEM datasets are discussed. It is shown that the estimation accuracy can be significantly increased by using ANNs, especially when the estimations of track modulus and its variations are required over short track section lengths, ANNs result in more accurate estimations compared to the use of equations from curve-fitting approaches. Results also show that ANNs are effective for the estimations of track modulus even when the noisy datasets are used for training the ANNs.

On the realizability of pressure–strain closures

2014 ◽  
Vol 755 ◽  
pp. 535-560 ◽  
Author(s):  
Aashwin A. Mishra ◽  
Sharath S. Girimaji
Keyword(s):  
Statistical Models ◽  
Flow Stability ◽  
Mean Flow ◽  
Model Formulation ◽  
Closure Model ◽  
Two Component ◽  
The Mean ◽  
The Relationship ◽  
Rapid Pressure ◽  
Domain Of Validity

AbstractThe realizability condition for statistical models of turbulence is augmented to ensure that not only is the Reynolds stress tensor positive semi-definite, but the process of its evolution is physically attainable as well. The mathematical constraints due to this process realizability requirement on the rapid pressure strain correlation are derived. The resulting constraints reveal important limits on the inter-component energy transfer and the consequent flow stability characteristics, as a function of the mean flow. For planar mean flows, the realizability constraints are most stringent for the case of purely sheared flows rather than elliptic flows. The relationship between the constraints and flow stability is explained. Process realizability leads to closure model guidance not only at the two-component (2C) limit of turbulence (as in the classical realizability approach) but throughout the anisotropy space. Consequently, the domain of validity and applicability of current models can be clearly identified for different mean flows. A simple framework for incorporating these process realizability constraints in model formulation is outlined.

Study on Machining of Cracking Notches for Automotive Connecting Rod Using WEDM

2010 ◽  
Vol 447-448 ◽  
pp. 228-232
Author(s):  
Yong Jun Tang ◽  
Yuan Bo Li ◽  
Yong Jun Zhang ◽  
Chun Qiang Zhou
Keyword(s):  
Cutting Speed ◽  
Connecting Rod ◽  
Electric Discharge Machine ◽  
Fracture Splitting ◽  
Discharge Machine ◽  
Wire Electric Discharge Machine ◽  
The Cost ◽  
The Relationship ◽  
In Virtue Of ◽  
Splitting Process

In order to resolve the problem of connecting rod notches machining, a new process of WEDM (Wire Electric Discharge Machine) has been presented, and it is greatly possible that expensive laser process can be replaced by WEDM in virtue of its unique advantages. Firstly, process parameters of notch have been analyzed, and project of machining notch using WEDM has been introduced, including measures to achieve good-quality notch. The relationship between cutting speed and power supply parameters has been investigated, and it is discovered that micro-crackle on bottom of notch are greatly effect to fracture splitting process, also new idea of active controlling micro-crackle has been presented. Finally, fracture splitting machining has been carried out. The cost and entrance standard of fracture splitting process are greatly dropped owing to new breakthrough of machining notch using WEDM.

Introduction

2017 ◽  
Author(s):  
Justin E. H. Smith
Keyword(s):  
History Of Philosophy ◽  
The Body ◽  
Necessary Condition ◽  
General Overview ◽  
History Of ◽  
European Thought ◽  
Relationship Of ◽  
The Relationship ◽  
In Virtue Of ◽  
Conceptual Relationship

This Introduction takes a broadly focused, global, and comparative view of the concept of embodiment, focusing particularly on some of the ways it has been interpreted outside of the history of European thought. It also provides a general overview of the central concerns and questions of the volume as a whole, such as: What is the historical and conceptual relationship between the idea of embodiment and the idea of subjecthood? Am I who I am principally in virtue of the fact that I have the body I have? Relatedly, what is the relationship of embodiment to being and to individuality? Is embodiment a necessary condition of being? Of being an individual? What are the theological dimensions of embodiment? To what extent has the concept of embodiment been deployed in the history of philosophy to contrast the created world with the state of existence enjoyed by God? What are the normative dimensions of theories of embodiment? To what extent is the problem of embodiment a distinctly western preoccupation?

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