Since the outbreak of COVID‐19 in December 2019, the severe acute respiratory syndrome coronavirus 2 (SARS CoV‐2) has spread worldwide. This study summarized the transmission mechanisms of COVID‐19 ...and their main influencing factors, such as airflow patterns, air temperature, relative humidity, and social distancing. The transmission characteristics in existing cases are providing more and more evidence that SARS CoV‐2 can be transmitted through the air. This investigation reviewed probabilistic and deterministic research methods, such as the Wells–Riley equation, the dose‐response model, the Monte‐Carlo model, computational fluid dynamics (CFD) with the Eulerian method, CFD with the Lagrangian method, and the experimental approach, that have been used for studying the airborne transmission mechanism. The Wells–Riley equation and dose‐response model are typically used for the assessment of the average infection risk. Only in combination with the Eulerian method or the Lagrangian method can these two methods obtain the spatial distribution of airborne particles' concentration and infection risk. In contrast with the Eulerian and Lagrangian methods, the Monte‐Carlo model is suitable for studying the infection risk when the behavior of individuals is highly random. Although researchers tend to use numerical methods to study the airborne transmission mechanism of COVID‐19, an experimental approach could often provide stronger evidence to prove the possibility of airborne transmission than a simple numerical model. All in all, the reviewed methods are helpful in the study of the airborne transmission mechanism of COVID‐19 and epidemic prevention and control.
In order to develop a dose‐response model for SARS coronavirus (SARS‐CoV), the pooled data sets for infection of transgenic mice susceptible to SARS‐CoV and infection of mice with murine hepatitis ...virus strain 1, which may be a clinically relevant model of SARS, were fit to beta‐Poisson and exponential models with the maximum likelihood method. The exponential model (k= 4.1 × l02) could describe the dose‐response relationship of the pooled data sets. The beta‐Poisson model did not provide a statistically significant improvement in fit. With the exponential model, the infectivity of SARS‐CoV was calculated and compared with those of other coronaviruses. The does of SARS‐CoV corresponding to 10% and 50% responses (illness) were estimated at 43 and 280 PFU, respectively. Its estimated infectivity was comparable to that of HCoV‐229E, known as an agent of human common cold, and also similar to those of some animal coronaviruses belonging to the same genetic group. Moreover, the exponential model was applied to the analysis of the epidemiological data of SARS outbreak that occurred at an apartment complex in Hong Kong in 2003. The estimated dose of SARS‐CoV for apartment residents during the outbreak, which was back‐calculated from the reported number of cases, ranged from 16 to 160 PFU/person, depending on the floor. The exponential model developed here is the sole dose‐response model for SARS‐CoV at the present and would enable us to understand the possibility for reemergence of SARS.
•Product innovations create employment at the firm-level.•The increase in employment associated with product innovation varies with innovation intensity.•Product innovations create more temporary and ...unskilled jobs than permanent and skilled jobs.•Simultaneous technological product and process innovation has a larger impact on employment than product innovation only.
Innovation has become a key interest in sub-Saharan Africa (SSA), as it is argued to be pervasive, and plays an eminent role in generating employment. There is, however, a dearth of empirical evidence assessing the impact of innovation on firm employment for SSA. This paper investigates the impact of product innovations on job creation using data from the recent waves of the Enterprise Survey merged with Innovation Follow-Up Survey for SSA countries for which both surveys are available. We apply the Dose Response Model under continuous and heterogeneous responses to treatment. The results reveal a positive impact of product innovations on total employment. This result is, however, found to hold only at specific intervals of product innovation intensities. Our analyses also show that product innovations tend to create both temporary and permanent jobs as well as skilled and unskilled jobs. However, the positive impact of product innovations on temporary and unskilled employment tends to outweigh that of permanent and skilled employment, raising questions about the security and quality of the new jobs generated by product innovations.
High-pressure pipelines that transport sour natural gas contain high levels of hydrogen sulfide, which is poisonous and has irreparable effects on human health even in low concentrations. These pipes ...are break valve-assisted and buried underground to minimize gas leakage and protect people nearby. This study examines their leakage through a series of time-dependent three-dimensional CFD simulations. In contradiction of previous works that only considered the above-ground environment, here, for more realism, the computational domain includes the pipeline, trench, covering soil, and above-ground environment. The impact of hole size, leak location on the pipe, wind velocity, atmospheric stability class, time of occurrence (day or night), and the presence of break valves on the dispersion of leaked gas are comprehensively investigated. Results indicate that the effect of hole diameter on hydrogen sulfide concentration in the above-ground environment is dominant to other factors. In addition, the probability of fatality due to gas release and the intensity of the gas leak exposure crisis are studied by combining the dose-response model and CFD simulation results. In this line, LT50, which measures how long it takes for 50% of people in different areas around the pipeline to die from exposure to hydrogen sulfide is calculated.
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•Transient CFD simulation of sour natural gas leak from buried transmission pipelines.•Simulating the leak process considering the effect of closing the line break valves.•Calculating the time required to reach a 50% probability of fatality around the pipe.•The size of leak hole has the most obvious effect on the intensity of gas dispersion.•The intensity of the gas leak exposure crisis was introduced and evaluated.
•Approaches to reflect biotic and abiotic agents affecting performance of wood-based building materials have been reviewed.•Efforts in developing performance models for fungal decay and mould growth ...have been intensified in recent years.•A framework is available to link exposure, design and the material-intrinsic ability to take up and release water.•Methods and models have the potential to get implemented in design guidelines and European and international standards.
Service life planning and performance classification are key issues in the building sector. Well-functioning ‘performance models’ are absolutely essential to predict the service life and functionality of buildings, building assets, and building products over time. Different types of performance models have been established for various building materials, but cannot necessarily transferred to wood-based materials, primarily due to their organic character. For performance modelling of wood products biological agents need to be considered, such as wood disfiguring and degrading organisms.
Different approaches to adequately reflect the influence of biotic and abiotic factors on the performance of wood have been reviewed and evaluated with respect to their usability in the building trade. We found that efforts in developing performance models for both fungal decay and mould growth have been intensified in recent years. A high heterogeneity among the numerous attempts became visible, different strategies have been followed, and were roughly distinguished according to the respective objectives, governing variables (e.g. mass loss, strength loss, remaining strength, decay ratings, service life, aesthetic appearance, etc.), data sources and the resulting level of accuracy.
A framework of how exposure, dimension, design details, and the material-intrinsic ability to take up and release water can be linked to model the moisture risk in wood products is in principal available. Methods and models have the potential to get implemented not only in design guidelines, but also in European and international standards. In particular, various dosimeter models could serve as reliable tools to quantify the effects of different construction details.
We demonstrated that floods can induce severe microbiological contamination of drinking water from wells and suggest strategies to better address water safety plans for groundwater drinking supplies. ...Since 2002, the Italian Water Research Institute (IRSA) has detected hepatitis A virus, adenovirus, rotavirus, norovirus, and enterovirus in water samples from wells in the Salento peninsula, southern Italy. Perturbations in the ionic strength in water flow can initiate strong virus detachments from terra rossa sediments in karst fractures. This study therefore explored the potential health impacts of prolonged runoff injections in Salento groundwater caused by severe flooding during October 2018. A mathematical model for virus fate and transport in fractures was applied to determine the impact of floodwater injection on groundwater quality by incorporating mechanisms that affect virus attachment/detachment and survival in flowing water at microscale. This model predicted target concentrations of enteric viruses that can occur unexpectedly in wells at considerable distances (5–8 km) from the runoff injection site (sinkhole). Subsequently, the health impact of viruses in drinking water supplied from contaminated wells was estimated during the summer on the Salento coast. Specific unpublished dose-response model coefficients were proposed to determine the infection probabilities for Echo-11 and Polio 1 enteroviruses through ingestion. The median (50%) risk of infection was estimated at 6.3 · 10−3 with an uncertainty of 23%. The predicted burden of diseases was 4.89 disability adjusted life years per year, i.e., twice the maximum tolerable disease burden. The results highlight the requirement for additional water disinfection treatments in Salento prior to the distribution of drinking water. Moreover, monthly controls of enteric virus occurrence in water from wells should be imposed by a new water framework directive in semiarid regions because of the vulnerability of karst carbonate aquifers to prolonged floodwater injections and enteric virus contamination.
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•Human health impact of prolonged floodwater injections in groundwater•Climate change impact makes virus presence in carbonate aquifers more likely.•Floodwater can enable virus detachments from terra rossa in limestone aquifers.•Virus occurrence in drinking water from wells far 8 km from flooding injections•Low count of fecal indicators does not prevent virus occurrence in drinking water.
The new challenges in toxicology demand novel and innovative in vitro approaches for deriving points of departure (PODs) and determining the mode of action (MOA) of chemicals. Therefore, the aim of ...this original study was to couple in vitro studies with untargeted metabolomics to model the concentration-response of extra- and intracellular metabolome data on human HepaRG cells treated for 48 h with three pyrrolizidine alkaloids (PAs): heliotrine, retrorsine and lasiocarpine. Modeling revealed that the three PAs induced various monotonic and, importantly, biphasic curves of metabolite content. Based on unannotated metabolites, the endometabolome was more sensitive than the exometabolome in terms of metabolomic effects, and benchmark concentrations (BMCs) confirmed that lasiocarpine was the most hepatotoxic PA. Regarding its MOA, impairment of lipid metabolism was highlighted at a very low BMC (first quartile, 0.003 µM). Moreover, results confirmed that lasiocarpine targets bile acids, as well as amino acid and steroid metabolisms. Analysis of the endometabolome, based on coupling concentration-response and PODs, gave encouraging results for ranking toxins according to their hepatotoxic effects. Therefore, this novel approach is a promising tool for next-generation risk assessment, readily applicable to a broad range of compounds and toxic endpoints.
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•PA effects on HepaRG cells were studied by concentration-response modelling and BMC.•The endometabolome was found to be more sensitive than the exometabolome.•LAS had the highest hepatotoxic potency, followed by HEL and RET.•The bell shape is the most frequent trend in response to LAS.•Lipids, bile acids and amino acids were especially affected by LAS.
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