Investigation of theoretical scaling laws using large eddy simulations for airborne spreading of viral contagion from sneezing and coughing

Using a set of large eddy point-particle simulations, we explore the fluid dynamics of an ejected puff resulting from a cough/sneeze. The ejection contains over 61 000 potentially virus-laden droplets at an injection Reynolds number of about 46 000, comparable to an actual cough/sneeze. We observe that global puff properties, such as centroid, puff volume, momentum, and buoyancy vary little across realizations. Other properties, such as maximum extent, shape, and edge velocity of the puff, may exhibit substantial variation. In many realizations, a portion of the puff splits off and advances along a random direction, while keeping airborne droplet nuclei afloat. This peeled-off portion provides a mechanism for virus-laden droplets to travel over large distances in a short amount of time. We also observe that the vast majority of droplets remain suspended within the puff after all liquid has evaporated. The main objectives of the study are to (i) evaluate assumptions of Balachandar\u27s et al. theory [Int. J. Multiphase Flow 132, 103439 (2020)], which include buoyancy effects, shape of the puff, and droplet evaporation rate, (ii) obtain values of closure parameters, which include location and time of the virtual origin, and puff entrainment and drag coefficients, and (iii) evaluate the accuracy of the theory in predicting the shape, size, and location of the puff, as well as droplet number density long after ejection. The theory adequately predicts global puff properties including size, velocity, and distance traveled, the largest size of droplets that exit the puff due to settling, and the droplet size distribution within the puff long after ejection

Urban consumers\u2019 attitudes and willingness to pay for functional foods in Iran: A case of dietary sugar

Growing concerns for the incidence of incurable diseases and high costs of health care have attracted consumers to functional foods in the world. These foods are characterized with health improvement, lower risk of disease incidence and less health hazards. The present work examined consumers' attitude and willingness to pay for dietary sugar in Rasht city, Iran. The studied sample included 125 citizens of Rasht in spring and summer of 2016 whose size was determined by Mitchell and Carson approach. Results of contingent valuation method on the basis of one-and-one-half-bound choice model revealed that the descriptive variable of bid had negative, statistically significant impact on the acceptance of bid by participants. In addition, the descriptive variables of respondent's age, educational level, family size, monthly income of the family, record of diabetes in family, healthy purchase attitude, and attitude towards the benefits of dietary sugar had positive, significant influence on bid acceptance. Participants expressed their willingness to pay 35.59% extra for dietary sugar as compared to conventional sugar

Secondary electron yield reduction by femtosecond pulse laser-induced periodic surface structuring

The electron-cloud phenomenon is one cause of beam instabilities in high intensity positive particle accelerators. Among the proposed techniques to mitigate or control this detrimental effect, micro-/nano-geometrical modifications of vacuum chamber surfaces are promising to reduce the number of emitted secondary electrons. Femtosecond laser surface structuring readily allows the fabrication of Laser Induced Periodic Surface Structures (LIPSS) and is utilized in several fields, but has not yet been tested for secondary electron emission reduction. In this study, such treatment is carried out on copper samples using linearly and circularly polarized femtosecond laser pulses. The influence of the formed surface textures on the secondary electron yield (SEY) is studied. We investigate the morphological properties as well as the chemical composition by means of SEM, AFM, Raman and XPS analyses. Surface modification with linearly polarized light is more effective than using circularly polarized light, leading to a significant SEY reduction. Even though the SEY maximum is only reduced to a value of ~1.7 compared to standard laser-induced surface roughening approaches, the femtosecond-LIPSS process enables to limit material ablation as well as the production of undesired dust, and drastically reduces the number of redeposited nanoparticles at the surface, which are detrimental for applications in particle accelerators. Moreover, conditioning tests reveal that LIPSS processed Cu can reach SEY values below unity at electron irradiation doses above 10−3 C/mm2

Financial crises and the attainment of the SDGs: an adjusted multidimensional poverty approach

This paper analyses the impact of financial crises on the Sustainable Development Goal of eradicating poverty. To do so, we develop an adjusted Multidimensional Poverty Framework (MPF) that includes 15 indicators that span across key poverty aspects related to income, basic needs, health, education and the environment. We then use an econometric model that allows us to examine the impact of financial crises on these indicators in 150 countries over the period 1980–2015. Our analysis produces new estimates on the impact of financial crises on poverty’s multiple social, economic and environmental aspects and equally important captures dynamic linkages between these aspects. Thus, we offer a better understanding of the potential impact of current debt dynamics on Multidimensional Poverty and demonstrate the need to move beyond the boundaries of SDG1, if we are to meet the target of eradicating poverty. Our results indicate that the current financial distress experienced by many low-income countries may reverse the progress that has been made hitherto in reducing poverty. We find that financial crises are associated with an approximately 10% increase of extreme poor in low-income countries. The impact is even stronger in some other poverty aspects. For instance, crises are associated with an average decrease of government spending in education by 17.72% in low-income countries. The dynamic linkages between most of the Multidimensional Poverty indicators, warn of a negative domino effect on a number of SDGs related to poverty, if there is a financial crisis shock. To pre-empt such a domino effect, the specific SDG target 17.4 on attaining long-term debt sustainability through coordinated policies plays a key role and requires urgent attention by the international community

Experimental Research on the Shear Connectors in Foam Concrete

In order to improve the longitudinal shear resistance between foam concrete and C-Channels, an investigation is carried out on the shear connectors in foam concrete with cold-formed steel double C-Channels embedment. Twenty-four tests have been carried out in two groups. Two types of connectors: flange connectors and web connectors are installed using self-drilling screws for a rapid construction. The experimental results show that they can effectively improve the longitudinal shear-resist capacity of the concrete. After the experiment, the specimens are dismantled for an interior observation. Based on the observation, the form of damage, the failure mechanism was discovered, and the equation of longitudinal shear capacity was developed. It is concluded that the failure involves independent slippage between two C-Channels and the shear connection fractures. Since the composite structure requires sufficient slip between the two materials, these types of shear connectors will have good enhancement for this type of composite structures subjected to dynamic loads

A Comparative, Historical Study of Gender Representation in Persian, English, and French Textbooks in Iran within a Seventy-year Period (1938-2015) with an Interdisciplinary Approach

Gender is an important cultural issue towards which there are different views in different cultures. Investigating the similarities and differences among cultures can shed light knowing that cultures. In this regard, educational systems play a vital role, either directly or indirectly, in familiarizing students with different cultures, and textbooks are recognized as one of the most important tools for framing students’ intellectual framework. This way, the specific purpose of the present study is to examine the representation of gender in Persian, English, and French textbooks written in a seventy-year old period (i.e. from 1938 to 2015). In this regard, nine textbooks including: 3 Persian textbooks written in 1940 (1319), 1984 (1361), and  2012 (1391); 3 French textbooks written in  1937  (1316),  1988  (1367),  and  2012  (1391);  and  3 English  textbooks  written  in  1940 (1319), 1984 (1361), and 2012 (1391) were gathered and investigated. The results of qualitative content analysis and frequency measures showed similarities and differences regarding the representation of gender in the textbooks that seem to have been less visible. Moreover, in English and French textbooks, there are some traces of bias towards females. The results of the present study could open new vistas towards intercultural relationships among Iran, England, and French