Dividend smoothing and credit rating changes

This paper examines the impact of credit rating changes on firms' dividend smoothing behavior, considering for the first time the"big three" credit rating agencies (Standard and Poor's, Fitch and Moody's). Using a hand collected sample of credit rating changes for firms listed at the S&P500 that are involved in dividend payments, we implement the traditional Lintner's (1956) model and we initially verify the fact that firms smooth their dividend payments. Then we consider the effect of credit rating changes on smoothing behavior and we show the presence of an asymmetric impact on credit rating changes to dividend smoothing behavior. In particular, on average, a credit rating downgrade among any of the three credit rating agencies forces firms to engage in less smoothing, whereas a credit rating upgrade has only a marginal positive effect on dividend smoothing. Finally, our key results remain valid for firms with high level of financial pressure and under various robustness checks

Droplet spatial distribution of oil-based emulsion spray

IntroductionOil-based emulsion solution is a common pesticide formulation in agricultural spraying, and its spray characteristics are different from that of water spraying. The well understanding of its spray characteristics is the theoretical basis to improve the pesticide spraying technology. The objective of the present study is to deepen the understanding of the spray characteristics of oil-based emulsion.MethodIn this paper, the spatial distribution characteristics of spray droplets of oil-based emulsion were captured visually using the high-speed photomicrography. On the basis of image processing method, the droplet size and distribution density of spray droplets at different spatial locations were analyzed quantitatively. The effects of nozzle configuration and emulsion concentration on spray structures and droplet spatial distribution were discussed.ResultsOil-based emulsion produced a special perforation atomization mechanism compared with water spray, which led to the increase of spray droplet size and distribution density. Nozzle configuration had a significant effect on oil-based emulsion spray, with the nozzle changed from ST110-01 to ST110-03 and ST110-05; the sheet lengths increased to 18 and 28 mm, respectively, whereas the volumetric median diameters increased to 51.19% and 76.00%, respectively. With emulsion concentration increased from 0.02% to 0.1% and 0.5%, the volumetric median diameters increased to 5.17% and 14.56%, respectively.DiscussionThe spray droplet size of oil-based emulsion spray can be scaled by the equivalent diameter of discharge orifice of nozzles. The products of volumetric median diameters and corresponding surface tensions were nearly constant for the oil-based emulsion spray of different emulsion concentrations. It is expected that this research could provide theoretical support for improving the spraying technology of oil-based emulsion and increasing the utilization of pesticide

Nondestructive measurement of kiwifruit firmness, soluble solid content (SSC), titratable acidity (TA), and sensory quality by vibration spectrum

Maturity is a key attribute to evaluate the quality and acceptability of fruit products. In this study, the impact method was used for nondestructive measurement of kiwifruit maturity. The fruit was vertically dropped onto an impact plate, and an accelerometer was used to measure the response signal. Then, fruit firmness, soluble solid content (SSC), titratable acidity (TA), and sensory scores were measured to determine the kiwifruit maturity. In addition, different modeling methods were proposed for data analysis. The results showed that the optimized prediction results were obtained by the principal component analysis–back-propagation neural network (PCA-BPNN) method for both quantitative and qualitative analysis. The optimized correlation coefficient between prediction and actual values (rp) and root mean square error of prediction (RESEP) for firmness, SSC, TA, and sensory score were 0.881 (2.359N), 0.641 (1.511 Brix), 0.568 (0.023%), and 0.935 (0.693), respectively. The optimized discriminant accuracy for immature, mature, and overmature kiwifruits was 94.2% and 92.1% for calibration and validation, respectively. Such results indicated the feasibility of the proposed impact method for kiwifruit maturity evaluation

Scattering of Plane Waves by Cylindrical Cavity in Unsaturated Poroelastic Medium

The scattering of elastic waves by underground cavities is an active research topic for its broad applications in various fields, such as earthquake engineering, the blast resistance of underground structures, geophysical exploration, etc. In most previous studies, the sounding medium was treated as an ideal elastic medium or a saturated poroelastic medium. The understanding of the scattering of elastic waves by cavities in unsaturated porous media is limited. In this study, the scattering of plane P1 waves and SV waves by a cavity with a permeable surface in an infinite unsaturated porous medium is solved by the wave function expansion method. The dynamic stress concentration at the cavity surface is investigated by taking P1 wave incidence, for example. Numerical results illustrate that the scattering of plane waves around the cavity strongly depends on the frequency of the incident waves, and the saturation, Poisson’s ratio, and porosity of the surrounding medium

Scattering of Plane Waves by Cylindrical Cavity in Unsaturated Poroelastic Medium

The scattering of elastic waves by underground cavities is an active research topic for its broad applications in various fields, such as earthquake engineering, the blast resistance of underground structures, geophysical exploration, etc. In most previous studies, the sounding medium was treated as an ideal elastic medium or a saturated poroelastic medium. The understanding of the scattering of elastic waves by cavities in unsaturated porous media is limited. In this study, the scattering of plane P1 waves and SV waves by a cavity with a permeable surface in an infinite unsaturated porous medium is solved by the wave function expansion method. The dynamic stress concentration at the cavity surface is investigated by taking P1 wave incidence, for example. Numerical results illustrate that the scattering of plane waves around the cavity strongly depends on the frequency of the incident waves, and the saturation, Poisson’s ratio, and porosity of the surrounding medium

Influenza vaccination uptake and its determinants during the 2019-2020 and early 2020-2021 flu seasons among migrants in Shanghai, China : a cross-sectional survey

Influenza vaccination coverage has generally been low in mainland China. However, few studies have attempted to measure influenza vaccination coverage among internal migrants in China who are at an increased risk of influenza infections. This study assessed influenza vaccination coverage and the factors associated with vaccination uptake among internal migrants in Shanghai, China. We conducted a cross-sectional online survey among a sample of migrants residing in Shanghai during November 1–20, 2020, to investigate vaccination uptake during the 2019–20 and early 2020–21 flu seasons (September to November 2020). Multivariable logistic regression was used to examine the factors associated with influenza vaccination uptake for the two flu seasons. About a quarter, 26.3%, and 24.4% of respondents reported receiving an influenza vaccination during the 2019–20 and early 2020–2021 flu seasons, respectively. Respondents who were divorced or widowed, had more household members (2 or ≥ 3), and considered themselves in good health were more likely to receive an influenza vaccine, regardless of the season. Respondents who perceived that they were highly susceptible to influenza and COVID-19 and those who reported ever consulting a medical professional about COVID-19 were more likely to have received a flu vaccination in the early 2020–21 flu season. The uptake of influenza vaccination among internal migrants in Shanghai was suboptimal. We found a range of factors linked to influenza vaccination uptake, pointing to the need for more in-depth evaluations on the underlying reasons driving the vaccination uptake among vulnerable populations in China, especially during the COVID-19 pandemic.publishedVersionPeer reviewe

Estimating Winter Wheat Plant Nitrogen Content by Combining Spectral and Texture Features Based on a Low-Cost UAV RGB System throughout the Growing Season

As prior information for precise nitrogen fertilization management, plant nitrogen content (PNC), which is obtained timely and accurately through a low-cost method, is of great significance for national grain security and sustainable social development. In this study, the potential of the low-cost unmanned aerial vehicle (UAV) RGB system was investigated for the rapid and accurate estimation of winter wheat PNC across the growing season. Specifically, texture features were utilized as complements to the commonly used spectral information. Five machine learning regression algorithms, including support vector machines (SVMs), classification and regression trees, artificial neural networks, K-nearest neighbors, and random forests, were employed to establish the bridge between UAV RGB image-derived features and ground-truth PNC, with multivariate linear regression serving as the reference. The results show that both spectral and texture features had significant correlations with ground-truth PNC, indicating the potential of low-cost UAV RGB images to estimate winter wheat PNC. The H channel, S4O6, and R_SE and R_EN had the highest correlation among the spectral indices, Gabor texture features, and grey level co-occurrence matrix texture features, with absolute Pearson’s correlation coefficient values of 0.63, 0.54, and 0.69, respectively. When the texture features were used together with spectral indices, the PNC estimation accuracy was enhanced, with the root mean square error (RMSE) decreasing from 2.56 to 2.24 g/kg, for instance, when using the SVM regression algorithm. The SVM regression algorithm with validation achieved the highest estimation accuracy, with a coefficient of determination (R2) of 0.62 and an RMSE of 2.15 g/kg based on the optimal feature combination of B_CON, B_M, G_DIS, H, NGBDI, R_EN, R_M, R_SE, S3O7, and VEG. Overall, this study demonstrated that the low-cost UAV RGB system could be successfully used to map the PNC of winter wheat across the growing season

Confidence, acceptance and willingness to pay for the COVID-19 vaccine among migrants in Shanghai, China : A cross-sectional study

Understanding the public’s attitude towards COVID-19 vaccination and their acceptance could help facilitate the COVID-19 rollout. This study aimed to assess the acceptance and willingness to pay (WTP) for the COVID-19 vaccine among migrants in Shanghai, China. A cross-sectional study was conducted among 2126 migrants in Shanghai for the period 1–20 November 2020. Convenience sampling was used to recruit respondents in workplaces with large numbers of migrant workers. Multivariable (ordered) logistic regressions were used to examine factors associated with acceptance and WTP of the COVID-19 vaccine. Most (89.1%) migrants would accept COVID-19 vaccination. Over 90.0% perceived the COVID-19 vaccine as important, while only 75.0% and 77.7% perceived vaccines safe and effective. Socio-demographic factors were not significantly associated with vaccine acceptance, but confidence in the importance (OR 8.71, 95% CI 5.89–12.89), safety (OR 1.80, 95% CI 1.24–2.61) and effectiveness (OR 2.66, 95% CI 1.83–3.87) of COVID-19 vaccine was significantly positively associated with vaccine acceptance. The top reasons for vaccine hesitancy were lack of vaccine information and confidence. The proportion of those definitely willing to get the COVID-19 vaccine was 20% lower if paid by themselves than free vaccination. Migrants were willing to pay a median amount of USD 46 for the COVID-19 vaccine. Results show that a high acceptance of the COVID-19 vaccine was universal among migrants in Shanghai. Concerns about vaccine safety, effectiveness and high costs of the COVID-19 vaccine may hinder their uptake. Effective health communication to build confidence in the COVID-19 vaccine and subsidies toward the costs of these vaccines are needed to improve uptake.publishedVersionPeer reviewe