Cost behavior in e-commerce firms

We conduct empirical research on the flexibility of operating costs of e-commerce firms. With an international sample of firms from different European countries, we find that e-commerce firms have a different cost structure than traditional retail firms, with a lower share of labor costs and cost of goods sold, but a higher share of other operating costs. While we find no significant different behavior in cost of goods sold and labor costs between the two types of firms, e-commerce firms are more flexible in adjusting other operating costs than traditional retail firms when activity decreases. Results are robust to different models, estimations methods and samples. The higher flexibility of e-commerce firms relies on other operating costs, but e-commerce creates qualified jobs with higher wages than traditional retail, with no additional exposure to labor uncertainty for employees.

Retrospective analysis of adverse effects associated with pyrethrins-containing products

The Pyrethrins Stewardship Program (PSP) was established to better understand adverse effects following exposure to pyrethrins-containing insecticide products. Running from April 2010 through December 2016, symptomatic dermal and inhalation exposures were entered into Phase I of the PSP and analyzed for exposure details and nature of the effects reported. Phase II consisted of an in-depth telephone interview using an enhanced questionnaire to investigate additional exposure details. Phase III scored the association between exposure and reported effects. Based on the data collected and analyzed, we conclude that: (1) Both in absolute number and relative to the wide distribution and use by consumers, adverse respiratory or dermal events after product exposure were rare; (2) Most outcomes for the reported events involving either dermal or respiratory effects were of minor severity and self-limiting; (3) None of the data collected and analyzed indicate that pyrethrins-containing products, including those formulated with synthetic pyrethroids and/or synergists, pose a significant risk of serious dermal or respiratory reactions even in cases where the exposed individual reported having allergies or asthma; (4) No additional label warnings or other mitigation techniques are warranted with pyrethrins-containing products formulated with or without synthetic pyrethroids and/or synergists.

RESEARCH OF THE ULTRASONIC DRYING PROCESS OF VARIOUS MATERIALS

В статье рассматривается процесс конвективной сушки тканых материалов и продуктов растительного происхождения. Показано, что длительность процесса может быть уменьшена за счет дополнительного воздействия ультразвуковыми колебаниями высокой интенсивности. Для определения ускорения процесса сушки ультразвуковыми колебаниями были разработаны лабораторные установки, позволяющие организовать комбинированное воздействие потока теплого воздуха и ультразвуковых колебаний. Комбинированная сушка ткани проводилась при трех различных температурах сушильного агента. Было установлено, что сокращение времени процесса по сравнению с конвективной сушкой зависит от температуры сушильного агента и составляет от 10% при температуре 40 0C до 20% при температуре 60 0C. В свою очередь, сушка овощей проводилась на резонансных промежутках от излучающего диска, при этом овощи нарезались толщиной 5 мм и располагались тонкими слоями. Комбинированная сушка моркови и картофеля позволила достичь сокращения времени сушки на 45-47%. При этом затраты на электроэнергию для ультразвукового аппарата составляют не более 30% от затрат на конвективную сушку. В результате проведенной работы была показана эффективность применения комбинированной ультразвуковой и конвективной сушки прежде всего для обезвоживания овощей, тогда как для ткани эффект не столь очевиден. Лабораторные исследования проводились при малом объеме высушиваемого материала, из-за слабого проникновения ультразвуковых колебаний на большую глубину, поэтому дальнейшие исследования необходимо направить на разработку полупромышленных и промышленных сушильных аппаратов для ультразвуковой сушки овощей и других термолабильных материалов. The article deals with the process of convective drying of fabrics and vegetables. The duration of the process can be reduced by additional exposure to high-intensity ultrasonic vibrations. To carry out drying, laboratory installations were developed that allow organizing the combined effect of a stream of warm air and ultrasonic vibrations. The combined drying of the fabric was carried out at three different temperatures of the drying agent and it was noted that the greatest reduction in drying time compared to convective drying was achieved at a temperature of 60 ° C. Although the overall reduction in drying time ranged from 10% to 20% depending on the temperature of the air flow. Drying of vegetables was carried out at resonance intervals from the emitting disk, while vegetables were cut 5 mm thick and placed in thin layers. Combined drying of carrots and potatoes made it possible to achieve a reduction in drying time of 45-47%. In this case, the cost of electricity for the ultrasonic apparatus is a small part of the cost of convective drying. As a result of the work carried out, it is possible to draw conclusions about the effectiveness of the use of combined ultrasonic and convective drying for dehydration of vegetables, while the effect is not so obvious for tissue. Laboratory studies were carried out with a small volume of dried material, due to the weak penetration of ultrasonic vibrations to a great depth, therefore, further research should be directed to the development of semi-industrial and industrial dryers for ultrasonic drying of vegetables and other heat-sensitive materials.

Racial/ethnic and educational inequities in restrictive abortion policy variation and adverse birth outcomes in the United States

Background To examine racial/ethnic and educational inequities in the relationship between state-level restrictive abortion policies and adverse birth outcomes from 2005 to 2015 in the United States. Methods Using a state-level abortion restrictiveness index comprised of 18 restrictive abortion policies, we conducted a retrospective longitudinal analysis examining whether race/ethnicity and education level moderated the relationship between the restrictiveness index and individual-level probabilities of preterm birth (PTB) and low birthweight (LBW). Data were obtained from the 2005–2015 National Center for Health Statistics Period Linked Live Birth-Infant Death Files and analyzed with linear probability models adjusted for individual- and state-level characteristics and state and year fixed-effects. Results Among 2,250,000 live births, 269,253 (12.0%) were PTBs and 182,960 (8.1%) were LBW. On average, states had approximately seven restrictive abortion policies enacted from 2005 to 2015. Black individuals experienced increased probability of PTB with additional exposure to restrictive abortion policies compared to non-Black individuals. Similarly, those with less than a college degree experienced increased probability of LBW with additional exposure to restrictive abortion policies compared to college graduates. For all analyses, inequities worsened as state environments grew increasingly restrictive. Conclusion Findings demonstrate that Black individuals at all educational levels and those with fewer years of education disproportionately experienced adverse birth outcomes associated with restrictive abortion policies. Restrictive abortion policies may compound existing racial/ethnic, socioeconomic, and intersecting racial/ethnic and socioeconomic perinatal and infant health inequities.

Candida albicans Antimicrobial and Antibiofilm Activity of Novel Endodontic Solvents

Background: Candida albicans is the most prevalent fungi isolated in endodontic infections. In this study, the ability of C. albicans biofilm to tolerate the novel solvent mixtures methyl ethyl ketone (MEK)/tetrachloroethylene (TCE) and MEK/orange oil (OOil) sequentially to the standard irrigation of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic (EDTA) was evaluated. Methods: Biofilm cell cultures of C. albicans SC 5314 were treated sequentially with NaOCl and EDTA and exposed to MEK/TCE or MEK/OOil. The effect of the antimicrobial treatment was evaluated using the disk diffusion method for planktonic culture, and the enumeration of colony-forming units (CFUs) and scanning electron microscope (SEM) for biofilm cell culture. Results: C. albicans mature biofilm (24 h) was significantly reduced in biomass and cell viability after solvent mixtures’ exposure, compared with the previous NaOCl and EDTA treatments. MEK/OOil combination caused a total reduction of biofilm, while with MEK/TCE, there was a 3-log (CFU/cm2) reduction compared with the sequence NaOCl and EDTA, and a 4-log (CFU/cm2) reduction compared with the control. Conclusions: The additional exposure of a preformed 24 h C. albicans biofilm to novel solvent mixtures MEK/TCE and MEK/OOil caused a positive antibiofilm impact, overcoming the performance of the conventional endodontic irrigating protocol.

Effects of Persistent Exposure to COVID-19 on Mental Health and Burnout Outcomes Among Trainees: A Longitudinal Study (Preprint)

BACKGROUND The rapid spread of the Coronavirus disease 2019 (COVID-19) has created considerable strain on the physical and mental health of healthcare workers around the world. The effects have been acute for physician trainees—a unique group functioning simultaneously as learners and care providers with limited autonomy. OBJECTIVE To investigate the longitudinal effects of physician trainee exposure to patients being tested for COVID-19 on stress, anxiety, depression and burnout using three surveys conducted during the early phase of the pandemic. METHODS All physician trainees (N=1375) at an academic medical center were invited to participate in a web-based survey. Multivariable models were used to assess the relationship between repeated exposure to patients being tested for COVID-19 and stress, anxiety, depression and burnout. RESULTS 389 trainees completed the baseline survey (28.3%). Of these, 191 and 136 responded to the ensuing surveys. Mean stress, anxiety and burnout decreased by 21% (95% Confidence Interval (CI): -28% to -12%; P < 0.001), 25% (95% CI: -36% to -11%; P < 0.001) and 13% (95% CI: -18% to -7%; P < 0.001), respectively per survey. However, for each survey time point, there was mean increase in stress, anxiety and burnout per additional exposure: stress [24% (95% CI: +12% to +38%; P < 0.001)], anxiety [22%, (95% CI: +2% to +46%; P = 0.026)], burnout [18%, (95% CI: +10% to +28%; P < 0.001)]. For depression, the association between exposure was strongest for the third survey, where mean depression scores increased by 33% per additional exposure (95% CI: +18% to +50%; P = <0.001). CONCLUSIONS Training programs should adapt to address the detrimental effects of the “pile up” of distress associated with persistent exposure through adaptive programs that allow flexibility for time off and recovery.

Transgenerational inheritance of BPA-induced obesity correlates with transmission of new CTCF sites in the Fto gene

The mechanisms by which epiphenotypes are transmitted transgenerationally through the parental germlines are poorly understood. Here we show that exposure of pregnant mouse F0 females during E7.5-E13.5 to bisphenol A results in obesity in the F2 progeny in the absence of additional exposure. This epiphenotype can be transmitted through the male and female germlines up to the F5 generation, decreases in F6, and disappears in F7. Analyses of chromatin changes in the sperm of the F1 generation reveal a widespread increase in chromatin accessibility at binding sites for CTCF and other transcription factors accompanied by alterations in 3D organization. Comparison of the transmission of obesity between F2 and F5 and its disappearance in F7 with alterations in the binding of these transcription factors points to the activation of two enhancers located in intronic and intergenic regions of the Fto gene as the cause of transgenerational inheritance. These enhancers form an autoregulatory feedback loop that, in combination with a decrease of m6A in sperm RNAs, may cause alterations of gene expression in the embryo after fertilization. Given the established involvement of SNPs in FTO in human obesity, the results suggest that both genetic and epigenetic alterations of the same gene can lead to the same phenotypic outcomes on human health.