scholarly journals Mechanistic transmission modeling of COVID-19 on the Diamond Princess cruise ship demonstrates the importance of aerosol transmission

2021 ◽  
Vol 118 (8) ◽  
pp. e2015482118 ◽  
Author(s):  
Parham Azimi ◽  
Zahra Keshavarz ◽  
Jose Guillermo Cedeno Laurent ◽  
Brent Stephens ◽  
Joseph G. Allen
Keyword(s):  
Long Range ◽  
Full Range ◽  
Quantitative Information ◽  
Relative Importance ◽  
Cruise Ship ◽  
Modeling Framework ◽  
Successful Model ◽  
Transmission Modes ◽  
Close Range ◽  
Transmission Factors

Several lines of existing evidence support the possibility of airborne transmission of coronavirus disease 2019 (COVID-19). However, quantitative information on the relative importance of transmission pathways of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains limited. To evaluate the relative importance of multiple transmission routes for SARS-CoV-2, we developed a modeling framework and leveraged detailed information available from the Diamond Princess cruise ship outbreak that occurred in early 2020. We modeled 21,600 scenarios to generate a matrix of solutions across a full range of assumptions for eight unknown or uncertain epidemic and mechanistic transmission factors. A total of 132 model iterations met acceptability criteria (R2 > 0.95 for modeled vs. reported cumulative daily cases and R2 > 0 for daily cases). Analyzing only these successful model iterations quantifies the likely contributions of each defined mode of transmission. Mean estimates of the contributions of short-range, long-range, and fomite transmission modes to infected cases across the entire simulation period were 35%, 35%, and 30%, respectively. Mean estimates of the contributions of larger respiratory droplets and smaller respiratory aerosols were 41% and 59%, respectively. Our results demonstrate that aerosol inhalation was likely the dominant contributor to COVID-19 transmission among the passengers, even considering a conservative assumption of high ventilation rates and no air recirculation conditions for the cruise ship. Moreover, close-range and long-range transmission likely contributed similarly to disease progression aboard the ship, with fomite transmission playing a smaller role. The passenger quarantine also affected the importance of each mode, demonstrating the impacts of the interventions.

scholarly journals Mechanistic Transmission Modeling of COVID-19 on the Diamond Princess Cruise Ship Demonstrates the Importance of Aerosol Transmission

2020 ◽  
Author(s):  
Parham Azimi ◽  
Zahra Keshavarz ◽  
Jose Guillermo Cedeno Laurent ◽  
Brent R. Stephens ◽  
Joseph G. Allen
Keyword(s):  
Long Range ◽  
Short Range ◽  
Full Range ◽  
Quantitative Information ◽  
Dominant Mode ◽  
Relative Importance ◽  
Cruise Ship ◽  
Infectious Dose ◽  
Cruise Ships ◽  
Respiratory Droplets

Background The current prevailing position is that coronavirus disease 2019 (COVID-19) is transmitted primarily through large respiratory droplets within close proximity (i.e., 1-2 m) of infected individuals. However, quantitative information on the relative importance of specific transmission pathways of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (i.e., droplets, aerosols, and fomites across short- and long-range distances) remains limited. Methods To evaluate the relative importance of multiple transmission routes for SARS-CoV-2, we leveraged detailed information available from the Diamond Princess Cruise Ship outbreak that occurred in early 2020. We developed a framework that combines stochastic Markov chain and negative exponential dose-response modeling with available empirical data on mechanisms of SARS-CoV-2 dynamics and human behaviors, which informs a modified version of the Reed-Frost epidemic model to predict daily and cumulative daily case counts on the ship. We modeled 21,600 scenarios to generate a matrix of solutions across a full range of assumptions for eight unknown or uncertain epidemic and mechanistic transmission factors, including the magnitude of droplet and aerosol emissions from infected individuals, the infectious dose for deposition of droplets and aerosols to the upper and lower respiratory tracts, and others. Findings A total of 132 model iterations met acceptability criteria (R2 > 0.95 for modeled vs. reported cumulative daily cases and R2 > 0 for daily cases). Analyzing only these successful model iterations yields insights into the likely values for uncertain parameters and quantifies the likely contributions of each defined mode of transmission. Mean estimates of the contributions of short-range, long-range, and fomite transmission modes to infected cases aboard the ship across the entire simulation time period were 35%, 35%, and 30%, respectively. Mean estimates of the contributions of large respiratory droplets and small respiratory aerosols were 41% and 59%. Short-range transmission was the dominant mode after passenger quarantine began, albeit due primarily to aerosol transmission, not droplets. Interpretation Our results demonstrate that aerosol inhalation was likely the dominant contributor to COVID-19 transmission among passengers aboard the Diamond Princess Cruise Ship. Moreover, close-range and long-range transmission likely contributed similarly to disease progression aboard the ship, with fomite transmission playing a smaller role. The passenger quarantine also affected the importance of each mode, demonstrating the impacts of the interventions. Although cruise ships represent unique built environments with high ventilation rates and no air recirculation, these findings underscore the importance of implementing public health measures that target the control of inhalation of aerosols in addition to ongoing measures targeting control of large droplet and fomite transmission, not only aboard cruise ships but in other indoor environments as well.

scholarly journals Experimental Study on Pressure Distribution and Flow Coefficient of Globe Valve

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 875 ◽  
Author(s):  
Quang Khai Nguyen ◽  
Kwang Hyo Jung ◽  
Gang Nam Lee ◽  
Sung Bu Suh ◽  
Peter To
Keyword(s):  
Reynolds Number ◽  
Pressure Distribution ◽  
Full Range ◽  
Flow Characteristics ◽  
National Standards ◽  
Flow Coefficient ◽  
Test Loop ◽  
Close Range ◽  
Valve Opening ◽  
Globe Valve

In this study, the pressure distribution and flow coefficient of a globe valve are investigated with a series of experiments conducted in a flow test loop. The experiments are performed on a three-inch model test valve from an eight-inch ANSI (American National Standards Institute) B16.11—Class 2500# prototype globe valve with various pump speeds and full range of valve openings. Both inherent and installed flow characteristics are measured, and the results show that the flow coefficient depends not only on the valve geometry and valve opening but also on the Reynolds number. When the Reynolds number exceeds a certain value, the flow coefficients are stable. In addition, the pressures at different positions in the upstream and the downstream of the valve are measured and compared with recommendation per ANSI/ISA-75.01 standard. The results show that, in single-phase flow, the discrepancies in pressure between different measurement locations within close range of 10 nominal diameter from the valve are inconsiderable.

scholarly journals merlin—A unified modeling framework for data analysis and methods development in Stata

2020 ◽  
Vol 20 (4) ◽  
pp. 763-784
Author(s):  
Michael J. Crowther
Keyword(s):  
Data Analysis ◽  
Data Science ◽  
Full Range ◽  
Hierarchical Structures ◽  
Nonlinear Effects ◽  
Recurrent Event ◽  
Data Types ◽  
Modeling Framework ◽  
Logistic Mixed Effects Model ◽  
Complex Settings

The challenges in statistics and data science are rapidly growing because access to a multitude of data types continues to increase, as well as the sheer quantity of data. Analysts are now presented with multivariate data, sometimes measured repeatedly, and often requiring the ability to model nonlinear relationships and hierarchical structures. In this article, I present the merlin command, which attempts to provide an extremely general framework for data analysis. From simple settings such as fitting a linear regression model or a Weibull survival model to more complex settings such as fitting a three-level logistic mixed-effects model or a multivariate joint model of multiple longitudinal outcomes (of different types) and a recurrent event and survival with nonlinear effects, merlin can fit them all. I will take a single dataset and attempt to show you the full range of capabilities of merlin and discuss some future directions for the implementation in Stata.

PALAEOMAGNETISM OF THE ABITIBI DYKE SWARM

1966 ◽  
Vol 3 (5) ◽  
pp. 671-683 ◽  
Author(s):  
A. Larochelle
Keyword(s):  
Long Range ◽  
Dyke Swarm ◽  
Relative Importance ◽  
Angular Dispersion ◽  
Range Correlation ◽  
Dyke Swarms

Previous data published on the palaeomagnetism of a group of Precambrian diabase dykes, referred to as the Abitibi swarm, were characterized by considerable angular dispersion attributed to a number of possible factors. The relative importance of these factors was investigated in the light of data obtained for an independent suite of samples from the same group of dykes. Most of the previous interpretation is probably no longer valid because the magnetization of the swarm was found to be distributed tightly about three mean directions rather than dispersed widely about one mean direction, as originally thought. It is concluded that the dykes forming the swarm were injected intermittently during several widely distinct periods and that, accordingly, long-range correlation of diabase dyke swarms on the sole basis of their palaeomagnetism may be more hazardous than was realized earlier.

scholarly journals Normalization and De-noising of Single-cell Hi-C Data with BandNorm and 3DVI

2021 ◽  
Author(s):  
Ye Zheng ◽  
Siqi Shen ◽  
Sündüz Keleş
Keyword(s):  
Single Cell ◽  
Long Range ◽  
High Throughput ◽  
State Of The Art ◽  
Cell Types ◽  
Chromatin Conformation ◽  
Modeling Framework ◽  
Technical Noise ◽  
Generative Modeling ◽  
Downstream Analysis

AbstractSingle-cell high-throughput chromatin conformation capture methodologies (scHi-C) enable profiling long-range genomic interactions at the single-cell resolution; however, data from these technologies are prone to technical noise and bias that, when unaccounted for, hinder downstream analysis. Here we developed a fast band normalization approach, BandNorm, and a deep generative modeling framework, 3DVI, to explicitly account for scHi-C specific technical biases. We present robust performances of BandNorm and 3DVI compared to existing state-of-the-art methods. BandNorm is effective in separating cell types, identification of interaction features, and recovery of cell-cell relationship, whereas de-noising by 3DVI successfully enables 3D compartments and domains recovery, especially for rare cell types.

scholarly journals Assessing the Accuracy and Feasibility of Using Close-Range Photogrammetry to Measure Channelized Erosion with a Consumer-Grade Camera

2020 ◽  
Vol 12 (11) ◽  
pp. 1706 ◽  
Author(s):  
Fangzhou Zheng ◽  
Rene Wackrow ◽  
Fan-Rui Meng ◽  
David Lobb ◽  
Sheng Li
Keyword(s):  
Field Experiment ◽  
Quantitative Information ◽  
Traditional Methods ◽  
Cross Sectional ◽  
Channel Size ◽  
Close Range Photogrammetry ◽  
Volumetric Assessment ◽  
Accuracy Level ◽  
Close Range ◽  
The Impact

Water-induced channel is one of the main forms of soil erosion in cultivated fields. Channelized erosion is often measured by the volume of the channels. Traditionally, the measurements were conducted with rulers or measuring tapes. However, these traditional methods are generally time- and labor-consuming and can cause soil surface disturbance. Close-range photogrammetry with a Consumer-Grade Camera (CGC-CRP) provides an alternative way of measuring channel volume and can overcome limitations of traditional methods and provides much higher spatial resolution. However, quantitative information on the accuracy of this technique is rare. In this study, the accuracy of the CGC-CRP method under different settings were examined with an in-house experiment and validated with a field experiment. In the in-house experiment, a wood board surface with Artificial Channels (AC) of different shapes, orientations, and sizes were built. These ACs were surveyed using the CGC-CRP method with a series of settings of shooting angles and image overlapping rates. Selected cross-sectional areas were extracted to compare against manual measurements to assess the absolute and relative errors of the CGC-CRP method. The applicability of the CGC-CRP method with different settings was evaluated by comparing time consumption and the size of detection areas. The results indicated that in order to maintain an acceptable accuracy level, the image overlapping rate should be ≥70%, and the shooting angle should be in the range of 60° to 80°. For the channel shape, the accuracy for V-channel was ~15% higher than that for U-channel. For the U-channel, the impact of the channel orientation on the accuracy was not significant when the shooting angle was relatively high, whereas for the V-channel, the vertically oriented channel had higher accuracy than horizontal or angle channels. Last, channel size did not strongly affect accuracy when the channel was vertically orientated, and the shooting angle and image overlapping rate were set in the optimum ranges. However, when the shooting angle or image overlapping rate was low, or when the channel was angled or horizontally orientated, the accuracy was lower with larger channel size. In the field experiment, under the optimum camera setting, the error for the ten cross-sectional areas was about 1.6%. This result suggests that the CGC-CRP method is promising in volumetric assessment of rill and gully erosion. The quantitative information on the accuracy provided in this study can help researchers to select the setting of CGC-CRP methods to achieve their required accuracy level.

scholarly journals Evaluation of Long-Range Mobile Mapping System (MMS) and Close-Range Photogrammetry for Deformation Monitoring. A Case Study of Cortes de Pallás in Valencia (Spain)

2020 ◽  
Vol 10 (19) ◽  
pp. 6831
Author(s):  
Francesco Di Stefano ◽  
Miriam Cabrelles ◽  
Luis García-Asenjo ◽  
José Luis Lerma ◽  
Eva Savina Malinverni ◽  
...  
Keyword(s):  
Long Range ◽  
New Technologies ◽  
3D Models ◽  
Deformation Monitoring ◽  
Mobile Mapping ◽  
Close Range Photogrammetry ◽  
Mapping System ◽  
Mobile Mapping System ◽  
Close Range ◽  
Landslide Deformation

This contribution describes the methodology applied to evaluate the suitability of a Long-Range Mobile Mapping System to be integrated with other techniques that are currently used in a large and complex landslide deformation monitoring project carried out in Cortes de Pallás, in Valencia (Spain). Periodical geodetic surveys provide a reference frame realized by 10 pillars and 15 additional check points placed in specific points of interest, all with millimetric accuracy. The combined use of Close-Range Photogrammetry provides a well-controlled 3D model with 1–3 cm accuracy, making the area ideal for testing new technologies. Since some zones of interest are usually obstructed by construction, trees, or lamp posts, a possible solution might be the supplementary use of dynamic scanning instruments with the mobile mapping solution Kaarta Stencil 2 to collect the missing data. However, the reliability of this technology has to be assessed and validated before being integrated into the existing 3D models in the well-controlled area of Cortes de Pallás. The results of the experiment show that the accuracy achieved are compatible with those obtained from Close-Range Photogrammetry and can also be safely used to supplement image-based information for monitoring with 3–8 cm overall accuracy.

Sign in / Sign up

Export Citation Format

Share Document