Local Transmissibility Research Articles

Mass gatherings for political expression had no discernible association with the local course of the COVID-19 pandemic in the USA in 2020 and 2021.

Epidemic disease can spread during mass gatherings. We assessed the impact of a type of mass gathering about which comprehensive data were available on the local-area trajectory of the COVID-19 epidemic. Here we examined five types of political event in 2020 and 2021: the US primary elections, the US Senate special election in Georgia, the gubernatorial elections in New Jersey and Virginia, Donald Trump's political rallies and the Black Lives Matter protests. Our study period encompassed over 700 such mass gatherings during multiple phases of the pandemic. We used data from the 48 contiguous states, representing 3,108 counties, and we implemented a novel extension of a recently developed non-parametric, generalized difference-in-difference estimator with a (high-quality) matching procedure for panel data to estimate the average effect of the gatherings on local mortality and other outcomes. There were no statistically significant increases in cases, deaths or a measure of epidemic transmissibility (Rt) in a 40-day period following large-scale political activities. We estimated small and statistically non-significant effects, corresponding to an average difference of -0.0567 deaths (95% CI = -0.319, 0.162) and 8.275 cases (95% CI = -1.383, 20.7) on each day for counties that held mass gatherings for political expression compared to matched control counties. In sum, there is no statistical evidence of a material increase in local COVID-19 deaths, cases or transmissibility after mass gatherings for political expression during the first 2 years of the pandemic in the USA. This may relate to the specific manner in which such activities are typically conducted.

Assessing the effectiveness of perimeter lockdowns as a response to epidemics at the urban scale

From September 2020 to May 2021 Madrid region (Spain) followed a rather unique non-pharmaceutical intervention (NPI) by establishing a strategy of perimeter lockdowns (PLs) that banned travels to and from areas satisfying certain epidemiological risk criteria. PLs were pursued to avoid harsher restrictions, but some studies have found that the particular implementation by Madrid authorities was rather ineffective. Based on Madrid’s case, we devise a general, minimal framework to investigate the PLs effectiveness by using a data-driven metapopulation epidemiological model of a city, and explore under which circumstances the PLs could be a good NPI. The model is informed with real mobility data from Madrid to contextualize its results, but it can be generalized elsewhere. The lowest lockdown activation threshold Theta considered (14-day cumulative incidence rate of 20 cases per every 10^5 inhabitants) shows a prevalence reduction >20% with respect to the scenario Theta =10^3, more akin to the case of Madrid, and assuming no further mitigation. Only the combination of Theta =20 and mobility reduction >90% can avoid PLs for more than >20% of the system. The combination of low Theta and strong local transmissibility reduction is key to minimize the impact, but the latter is harder to achieve given that we assume a situation with highly mitigated transmission, resembling the one observed during the second wave of COVID-19 in Madrid. Thus, we conclude that a generalized lockdown is hard to avoid under any realistic setting if only this strategy is applied.

Modal Identification of Train Passenger Seats Based on Dynamic Tests and Output-Only Techniques

Railways are one of the most efficient and widely used mass transportation systems for mid-range distances, also being pointed out as the best strategy to reach European Union decarbonisation goals. However, to increase railways attractiveness, it is necessary to improve the quality of the ride, namely its comfort, by decreasing the vibration at the passenger level. This article describes the experimental vibration modal identification of train seats based on a dedicated set of dynamic tests performed on Alfa Pendular and Intercity trains. This work uses two output-only modal identification techniques: the transmissibility functions and the Enhanced Frequency Domain Decomposition (EFDD) method. The last method allows us to clearly distinguish the seat structural movements, particularly the ones related to torsion and bending of the seat frame, from the local vertical foam vibrations. The natural frequencies and mode shapes are validated by matching the results derived from the transmissibility functions and EFDD method. The identified modal parameters are particularly relevant to characterise the vibration transmissibility provided by the foams (local transmissibility) and the vibration transmissibility derived from the metallic seat frame (global transmissibility).

Estimation of local transmissibility in the early phase of monkeypox epidemic in 2022

ObjectivesTo estimate the basic reproductive number (Ro) to help us understand and control the spread of monkeypox in immunologically naive populations. MethodsUsing three highest incidence populations including England, Portugal, and Spain as examples as of 18 June 2022, we employed the branching process with a Poisson likelihood and gamma-distributed serial interval to fit daily reported case data of monkeypox to estimate Ro. Sensitivity analyses were performed by varying mean serial interval from 6.8 to 12.8 days. ResultsThe median posterior estimates of Ro for monkeypox in the three study populations were statistically >1 (England: Ro = 1.60 [95% (credible interval) CrI, 1.50–1.70]; Portugal: Ro = 1.40 [95% CrI, 1.20–1.60]; Spain: Ro = 1.80 [95% CrI, 1.70–2.00]). Ro estimates varied over 1.30 to 2.10, depending on the serial interval. DiscussionThe updated Ro estimates across different populations will inform policy makers' plans for public health control measures. Currently, monkeypox has a sustainable outbreak potential and may challenge healthcare systems, mainly due to declines in the population level immunity to Orthopoxviruses since the cessation of routine smallpox vaccination. Smallpox vaccination has been shown to be effective in protecting (≤85% effectiveness) against monkeypox infection in earlier times. So early postexposure vaccination is currently being offered in an attempt to control its spread.

Travel ban effects on SARS-CoV-2 transmission lineages in the UAE as inferred by genomic epidemiology.

Global and local whole genome sequencing of SARS-CoV-2 enables the tracing of domestic and international transmissions. We sequenced Viral RNA from 37 sampled Covid-19 patients with RT-PCR-confirmed infections across the UAE and developed time-resolved phylogenies with 69 local and 3,894 global genome sequences. Furthermore, we investigated specific clades associated with the UAE cohort and, their global diversity, introduction events and inferred domestic and international virus transmissions between January and June 2020. The study comprehensively characterized the genomic aspects of the virus and its spread within the UAE and identified that the prevalence shift of the D614G mutation was due to the later introductions of the G-variant associated with international travel, rather than higher local transmissibility. For clades spanning different emirates, the most recent common ancestors pre-date domestic travel bans. In conclusion, we observe a steep and sustained decline of international transmissions immediately following the introduction of international travel restrictions.

Sensitivity analysis of the infection transmissibility in the UK during the COVID-19 pandemic.

The coronavirus (COVID-19) outbreak started in December 2019 and rapidly spread around the world affecting millions of people. With the growth of infection rate, many countries adopted different policies to control the spread of the disease. The UK implemented strict rules instructing individuals to stay at home except in some special circumstances starting from 23 March 2020. Accordingly, this study focuses on sensitivity analysis of transmissibility of the infection as the effects of removing restrictions, for example by returning different occupational groups to their normal working environment and its effect on the reproduction number in the UK. For this reason, available social contact matrices are adopted for the population of UK to account for the average number of contacts. Different scenarios are then considered to analyse the variability of total contacts on the reproduction number in the UK as a whole and each of its four nations. Our data-driven retrospective analysis shows that if more than 38.5% of UK working-age population return to their normal working environment, the reproduction number in the UK is expected to be higher than 1. However, analysis of each nation, separately, shows that local reproduction number in each nation may be different and requires more adequate analysis. Accordingly, we believe that using statistical methods and historical data can provide good estimation of local transmissibility and reproduction number in any region. As a consequence of this analysis, efforts to reduce the restrictions should be implemented locally via different control policies. It is important that these policies consider the social contacts, population density, and the occupational groups that are specific to each region.

Identification of structural parameters and boundary conditions using a minimum number of measurement points

This article proposes a novel methodology that uses mathematical and numerical models of a structure to build a data set and determine crucial nodes that possess the highest sensitivity. Regression surfaces between the structural parameters and structural output features, represented by the natural frequencies of the structure and local transmissibility, are built using the numerical data set. A description of a possible experimental application is provided, where sensors are mounted at crucial nodes, and the natural frequencies and local transmissibility at each natural frequency are determined from the power spectral density and the power spectral density ratios of the sensor responses, respectively. An inverse iterative process is then applied to identify the structural parameters by matching the experimental features with the available parameters in the myriad numerical data set. Three examples are presented to demonstrate the feasibility and efficacy of the proposed methodology. The results reveal that the method was able to accurately identify the boundary coefficients and physical parameters of the Euler-Bernoulli beam as well as a highway bridge model with elastic foundations using only two measurement points. It is expected that the proposed method will have practical applications in the identification and analysis of restored structural systems with unknown parameters and boundary coefficients.

Transmissibility of coronavirus disease 2019 in Chinese cities with different dynamics of imported cases.

BackgroundMonitoring the reproduction number (Rt) of the disease could help determine whether there is sustained transmission in a population, but areas with similar epidemic trends could have different transmission dynamics given the risk from imported cases varied across regions. In this study, we examined the Rt of coronavirus disease 2019 (COVID-19) by taking different dynamics of imported cases into account and compared the transmissibility of COVID-19 at different intervention periods in Hangzhou and Shenzhen.MethodsWe obtained the daily aggregated counts of laboratory-confirmed imported and local cases of COVID-19 infections in Hangzhou and Shenzhen from January 1 to March 13, 2020. Daily Rt and piecewise Rt before and after Wuhan lockdown were estimated, accounting for imported cases.ResultsSince the epidemic of COVID-19 in Shenzhen was dominated by imported cases, Rt was around 0.1 to 0.7 before the Wuhan lockdown. After the lockdown of Wuhan and the initialization of measures in response to the outbreak, local transmission was well-controlled as indicated by a low estimated value of piecewise Rt, 0.15 (95% CI [0.09–0.21]). On the contrary, Rt obtained for Hangzhou ranged from 1.2 to 4.9 with a piecewise Rt of 2.55 (95% CI [2.13–2.97]) before the lockdown of Wuhan due to the surge in local cases. Because of the Wuhan lockdown and other outbreak response measures, Rt dropped below unity in mid-February.ConclusionsEven though Shenzhen had more cases than Hangzhou, local transmission did not sustain probably due to limited transmission from imported cases owing to the reduction in local susceptibles as residents left the city during Chunyun. The lockdown measures and local outbreak responses helped reduce the local transmissibility.

Meteorological conditions and nonpharmaceutical interventions jointly determined local transmissibility of COVID-19 in 41 Chinese cities: A retrospective observational study

BackgroundBefore effective vaccines become widely available, sufficient understanding of the impacts of climate, human movement and non-pharmaceutical interventions on the transmissibility of COVID-19 is needed but still lacking. MethodsWe collected by crowdsourcing a database of 11 003 COVID-19 cases from 305 cities outside Hubei Province from December 31, 2019 to April 27, 2020. We estimated the daily effective reproduction numbers (Rt) of COVID-19 in 41 cities where the crowdsourced case data are comparable to the official surveillance data. The impacts of meteorological variables, human movement indices and nonpharmaceutical emergency responses on Rt were evaluated with generalized estimation equation models. FindingsThe median Rt was 0•46 (IQR: 0•37–0•87) in the northern cities, higher than 0•20 (IQR: 0•09–0•52) in the southern cities (p=0•004). A higher local transmissibility of COVID-19 was associated with a low temperature, a relative humidity near 70–75%, and higher intracity and intercity human movement. An increase in temperature from 0℃ to 20℃ would reduce Rt by 30% (95 CI 10–46%). A further increase to 30℃ would result in another 17% (95% CI 5–27%) reduction. An increase in relative humidity from 40% to 75% would raise the transmissibility by 47% (95% CI 9–97%), but a further increase to 90% would reduce the transmissibility by 12% (95% CI 4–19%). The decrease in intracity human movement as a part of the highest-level emergency response in China reduced the transmissibility by 36% (95% CI 27–44%), compared to 5% (95% CI 1–9%) for restricting intercity transport. Other nonpharmaceutical interventions further reduced Rt by 39% (95% CI 31–47%). InterpretationClimate can affect the transmission of COVID-19 where effective interventions are implemented. Restrictions on intracity human movement may be needed in places where other nonpharmaceutical interventions are unable to mitigate local transmission. FundingChina Mega-Project on Infectious Disease Prevention; U.S. National Institutes of Health and National Science Foundation.

A Discrete fracture–matrix model for pressure transient analysis in multistage fractured horizontal wells with discretely distributed natural fractures

Analysis of transient pressure test has become a reliable and powerful tool for petroleum engineers to study the impacts of complex fracture networks on multistage fractured horizontal wells (MFHWs) in unconventional reservoirs. Although lots of models have been established in the past decades, such as well-known dual-porosity model (DPM), dual-permeability model (DKM) and stripe fracture model (SFM), they have been proven unsuitable for modeling discretely distributed natural fractures (NFs).In this study, to overcome the disadvantages of existing models, a Discrete fracture–matrix method based on numerical well testing model (DFM-WTM) is proposed to study the pressure transient responses of MFHW with discretely distributed NFs. In DFM-WTM, local grid refinement method, well model and transmissibility corrections, natural fracture generation and time-step size are improved based on the framework of Matlab Reservoir Simulation Toolbox (MRST) (Lie, 2019), ensuring that pressure transient responses of MFHW with complex fracture networks can be obtained accurately and efficiently. Then, sensitivity analysis is conducted to study the impacts of different fracture properties. Finally, a case study is performed to further demonstrate the reliability and practicality of DFM-WTM.The results show that MFHW with discretely distributed NFs can be divided into 8 flow regimes, including (1) wellbore storage and skin effect, (2) fracture linear flow, (3) bilinear flow, (4) NF–HF fluid supply, (5) second bilinear flow, (6) formation linear flow, (7) pseudo boundary flow and (8) pseudo radial flow. Besides, a “dip” is found in the pressure derivative curve which is caused by the NF–HF fluid supply. Through the sensitivity analysis, it is found that this “dip” is an important signal to identify the impacts of NFs. It can also help us fathom the properties of HFs and NFs because this “dip” can be mainly affected by the number and conductivity of both HFs and NFs.

Downgrading disease transmission risk estimates using terminal importations.

As emerging and re-emerging infectious arboviruses like dengue, chikungunya, and Zika threaten new populations worldwide, officials scramble to assess local severity and transmissibility, with little to no epidemiological history to draw upon. Indirect estimates of risk from vector habitat suitability maps are prone to great uncertainty, while direct estimates from epidemiological data are only possible after cases accumulate and, given environmental constraints on arbovirus transmission, cannot be widely generalized beyond the focal region. Combining these complementary methods, we use disease importation and transmission data to improve the accuracy and precision of a priori ecological risk estimates. We demonstrate this approach by estimating the spatiotemporal risks of Zika virus transmission throughout Texas, a high-risk region in the southern United States. Our estimates are, on average, 80% lower than published ecological estimates—with only six of 254 Texas counties deemed capable of sustaining a Zika epidemic—and they are consistent with the number of autochthonous cases detected in 2017. Importantly our method provides a framework for model comparison, as our mechanistic understanding of arbovirus transmission continues to improve. Real-time updating of prior risk estimates as importations and outbreaks arise can thereby provide critical, early insight into local transmission risks as emerging arboviruses expand their global reach.

Rapid and accurate simulation of the In-situ Conversion Process using upscaled dynamic models

Numerical modeling of the In-situ Conversion Process (ICP) is a challenging endeavor involving non-isothermal multiphase flow, compositional PVT behavior, and chemical reactions that convert solid kerogen into light hydrocarbons and are tightly coupled to the temperature propagation. The objective of the reported work is to significantly accelerate the ICP simulations using fast upscaled dynamic models that deliver good prediction accuracy. We take advantage of the fluid- and heat-flow based local transmissibility upscaling techniques. A fully automatic scale-up workflow is scripted for pattern-scale ICP models, which generates upscaled models that are, in turn, simulated using a proprietary simulator. We demonstrate the consistency, accuracy, and efficiency of the upscaling workflow using a realistic pattern-scale ICP model.A simple yet effective upscaling workflow is developed for the fast and accurate simulation of ICP using a novel integrated upscaling and flow simulation platform. Overall, the upscaling workflow is simple, generic, and delivers computational speed-up while retaining a reasonable level of fine-scale model accuracy. Upscaled models lead to more robust simulations of ICP from the numerical perspective as evidenced by main numerical performance indicators. The upscaling script is implemented as part of an easily customizable ICP simulation deck. It is used for simulation-intensive ICP performance forecasting workflows (e.g., optimization, uncertainty quantification, and history matching) targeting oil-shale resources worldwide.

A semi-analytical solution to the transient temperature behavior along the vertical wellbore after well shut-in

Temperature measured from a permanent downhole gauge in a well after the well shut-in provides a unique perspective for surveillance and production management. For example, in deepwater environment, production engineer needs to know the temperature of a shut-in well before it is being restarted since different temperature profiles along the wellbore may need very different restarting strategies for flow assurance purpose. A number from the “rule-of-thumb” or running complicated numerical simulation is either not reliable or impractical. This paper presents a semi-analytical model to estimate the temperature transient behavior after the well shut-in. The temperature at a point along the wellbore, which is useful for production management and flow assurance, is solved and the solution can be easily implemented for calculating temperature history. The temperature profile solution for locations along the wellbore is also presented in the paper. Furthermore, matching the calculated temperature with the measured temperature at the same location will yield the well local heat transmissibility coefficient. The applications of the solution to this model are multiple folders and a deepwater field example is provided to demonstrate some applications and valid the results.

Integration of local–global upscaling and grid adaptivity for simulation of subsurface flow in heterogeneous formations

We propose a methodology, called multilevel local–global (MLLG) upscaling, for generating accurate upscaled models of permeabilities or transmissibilities for flow simulation on adapted grids in heterogeneous subsurface formations. The method generates an initial adapted grid based on the given fine-scale reservoir heterogeneity and potential flow paths. It then applies local–global (LG) upscaling for permeability or transmissibility [7], along with adaptivity, in an iterative manner. In each iteration of MLLG, the grid can be adapted where needed to reduce flow solver and upscaling errors. The adaptivity is controlled with a flow-based indicator. The iterative process is continued until consistency between the global solve on the adapted grid and the local solves is obtained. While each application of LG upscaling is also an iterative process, this inner iteration generally takes only one or two iterations to converge. Furthermore, the number of outer iterations is bounded above, and hence, the computational costs of this approach are low. We design a new flow-based weighting of transmissibility values in LG upscaling that significantly improves the accuracy of LG and MLLG over traditional local transmissibility calculations. For highly heterogeneous (e.g., channelized) systems, the integration of grid adaptivity and LG upscaling is shown to consistently provide more accurate coarse-scale models for global flow, relative to reference fine-scale results, than do existing upscaling techniques applied to uniform grids of similar densities. Another attractive property of the integration of upscaling and adaptivity is that process dependency is strongly reduced, that is, the approach computes accurate global flow results also for flows driven by boundary conditions different from the generic boundary conditions used to compute the upscaled parameters. The method is demonstrated on Cartesian cell-based anisotropic refinement (CCAR) grids, but it can be applied to other adaptation strategies for structured grids and extended to unstructured grids.

Hand vibration: non-contact measurement of local transmissibility

Grip and push forces required for the use of vibrating tools are considered important influencing inputs for the assessment of hand-vibration transmissibility (TR). At present TR measurements are usually referred to the palm of the hand The aims of the present paper are: to present an original measurement procedure for non-contact assessment of the transmissibility of fingers; to report TR data measured on six points of the hand of nine subjects; to correlate TR with: grip, push, hand volume and BMI. Tests have been carried out using a cylindrical handle mounted on an shaker. A laser Doppler vibrometer is used to measure the vibration velocity. Push force is measured using a force platform, whereas grip force is measured using a capacitive pressure sensor matrix wrapped around the handle. Tests have been conducted on nine healthy subjects. Proximal and distal regions of the second, fourth and fifth fingers have been investigated. Tests were carried out using a push force of: 25, 50 and 75 N. The excitation signal was a broadband random vibration in the band 16-400 Hz with un-weighted rms acceleration level of 6 m/s(2). Results show how in general TR values measured on distal points are higher respect to the proximal points. A resonance peak is present for all the measured points in the band 55-80 Hz. ANOVA analysis showed that TR is not significantly dependent on: BMI, hand volume and push force alone. While TR is significantly dependent on: grip force alone, measurement positions and grip and push force together. The proposed procedure shows the advantage to allow local vibration measurement directly on the fingers without the necessity to apply any contact sensor. Results demonstrate how the transmissibility is significantly different on the point where the acceleration is measured.

Structured flow-based gridding and upscaling for modeling subsurface flow

The combined use of flow-based grid generation and equivalent property calculation offers an effective means for generating subsurface flow simulation models from highly detailed geological descriptions. In this paper, several structured grid generation procedures, specifically a streamline-based method, a Jacobian-based elliptic grid generation approach, and an optimization technique, are investigated for this purpose. The ability of the more advanced methods to resolve both flow information and geological features is illustrated. In addition, both (local) permeability and (global) transmissibility upscaling methods are implemented in conjunction with the gridding approaches. The benefits of structured flow-based grids over uniform Cartesian grids are demonstrated for several three-dimensional cases. It is shown that these grids are most effective when a limited number of features dominate the flow. In addition, consistent with earlier work, global transmissibility upscaling is found to be preferable to permeability upscaling for highly heterogeneous systems.

Local oxygen transmissibility of disposable contact lenses

Aim: Despite global standardisation in measurement of oxygen transmissibility (Dk/ t), in our clinic we continue to see limbal vasculature changes in patients wearing some disposable lenses. The use of central Dk/ t as a simple designator of a contact lens oxygen performance has clearly failed, it being acknowledged as often unrelated to the oxygen performance of the lens periphery. This study investigates a new criterion for contact lens oxygen transmissibility, the local Dk/ t. Method: The study measured 20 spherical disposable lens brands (power range: −15.00 to +8.00 D) and 8 toric lens brands (power range: −8.00 to +4.00 D sphere, with a −1.00 D/−1.25 D×180). An electro-mechanical gauge (Heidenhain, Germany) was used to measure lens thickness ( t) at different positions on the lens. Oxygen permeability (Dk) of each lens material was calculated from the equation Dk=1.67 e (0.0397× water content ) of Morgan and Efron [Contact Lens Anterior Eye 21 (1998) 3] who used ISO/ANSI standard methodologies. The local Dk/ t value was calculated from the point of maximum thickness on the lens and compared to the criterion of 12 Fatt units set by Benjamin [Int. Contact Lens Clin. 23 (1996) 188], to provide corneal oxygenation greater than or comparable to that available in the normal closed eye. Results: All lens types with a water content over 65% had a local Dk/ t of 12 Fatt units or more for most or all lens powers: CIBAVision FocusDailies, Bausch & Lomb Soflens66, CooperVision Actifresh400, and CIBAVision PrecisionUV. In addition, some lenses in the 55–62% water content range had some lens powers with a local Dk/ t in excess of 12: CooperVision Proclear, Johnson & Johnson Acuvue 1 and CIBAVision Focus 2 week. None of the disposable toric lenses had a minimum Dk/ t of 12 or more. The silicone-hydrogels, Bausch & Lomb PureVision and CIBAVision Focus Night&Day, comfortably exceeded Dk/ t of 50 for all lens powers. Conclusion: Some current disposable soft lenses have local Dk/ t values below physiological requirements. Contact lens manufacturers and international standards organisations should consider introducing the labelling of local Dk/ t values on lens packaging so that clinicians can make informed prescribing decisions.

Effects of hydrogel lens transmissibility profiles on local corneal swelling during eye closure.

To develop a unified model for describing the relations among local and regional contact lens transmissibility, topographical corneal location, and lens-induced corneal swelling under the closed eye. Thirteen adult male subjects, all adapted to daily wear of hydrogel lenses, wore a series of hydrogel lenses under patched eyes for 4 h. Corneal swelling was determined using an optical pachometer for five sites along the vertical meridian of test corneas. Four of the test conditions involved approximately uniform (no lens or parallel lenses) oxygen barriers over the central 8 mm of the cornea. Four additional sessions involved test lenses of -6, -3, +3, and +6 D, all having a center thickness of 0.2 mm. For the uniform barrier conditions, corneal swelling followed a similar pattern at all sites. Swelling was greatest centrally and least at the most peripheral, 7 mm, chord. The swelling vs. lens thickness response could be closely described by a third-order polynomial. Swelling with nonuniform thickness lenses at all sites showed evidence of small thickness averaging effects. Average central corneal swelling under the nonuniform lenses could be estimated from the polynomial function by averaging lens thickness over 5.5 to 6.75 mm for minus lenses and approximately 7.75 mm for plus lenses. The corneal swelling response to closed eye wear of hydrogel lenses follows a well ordered course over the central 7 mm. Over the same topographical area, the degree of swelling is influenced by both local and regional lens thickness profiles.