The main contribution in this article is threefold:(1)we show the necessary and sufficient condition for graphs to be fractional(g,f)-covered which can be expressed in different forms,and extended to fractional(g,f,m)-covered graphs;(2)the concept of fractional-critical covered graph is put forward and its necessary and sufficient condition is given;(3)we present the degree condition for a graph to be fractional(g,f,n′,m)-critical covered,and show that degree bound is sharp when m is small.Moreover,the related result in fractional(a,b,n′,m)-critical covered setting is also verified.
In Northwest China,potatoes are cultivated on double-rows of each ridge which is mulched with plastic film,and the film is covered with some of soil.While effective in retaining soil moisture,this technique can render the potato seedlings prone to be burned if they are not released from the plastic film in time.In this study,the model of convective heat transfer of potato ridge under solar radiation and atmospheric radiation is established by the Fluent software.The processes of the heat transfer of potato ridge was simulated for a certain day,and the temperature distribution in the potato ridge was monitored over time.The temperature distribution of soil in the growth layer of potato plants was analyzed under different thickness and widths of the covering soil on the film.The results showed that with the increase of covering soil thickness and width,the time for soil at different depth to reach the peak-temperature was delayed,and the daily temperature change of soil where the different depths layer of potato plants growth was reduced.At that time,a binary regression equation of offset temperature was constructed by using the Response Surface Method.The best parameter combination for covering soil on the plastic film is a thickness of 50 mm and a width of 280 mm in the cold and arid areas of Northwest China.However,the offset temperature(PT)first decreased and then almost remained unchanged with the increase of covering soil thickness.Considering the operational efficiency and power consumption of soil covering devices in the field,the unchanged width of the covering soil is 200 mm.The field experiments have shown that a 50 mm thick of soil covering is beneficial for the growth of potato plants and a 200 mm width of soil covering is beneficial for the growth of potato plants.The height of potato plants was 21 cm,and the natural emergence rate of potatoes was 95.8%on June 9,2024.The environment of soil covered could provide theoretical support for the mechanized planting of potatoes.
Quandong LiuWei SunYongmei WangJuanling WangXinglong Che
Objective Antiretroviral drugs covered by medical insurance have been gradually used by people living with human immunodeficiency virus(PLWH)in recent years in China.This study aimed to analyze their willingness to pay(WTP)for antiretroviral drugs.Methods A mixed-methods study design involving a cross-sectional survey and in-depth interviews was conducted.A cross-sectional survey was performed to collect data on the general characteristics,economic status,antiretroviral therapy(ART)status,and WTP of PLWH in 18 Chinese cities from August 2022 to February 2023.Multivariate logistic regression was used to analyze the factors associated with WTP.Representatives of PLWH were interviewed via in-depth interviews,and the data were thematically analyzed.Results Among the 941 PLWH,271(28.80%)were willing to pay for antiretroviral drugs covered by medical insurance.For basic medical insurance for urban and rural residents,PLWH with the following characteristics were more willing to pay:an educational level of senior high school or technical secondary school,having an undergraduate degree or higher,frequently working away from their hometowns,and homosexual transmission.Off-farm workers and recipients of government medical aid were more unwilling to pay.For basic medical insurance for urban employees,PLWH with the following characteristics were more willing to pay:frequently working away from their hometowns;homosexual transmission;personal annual income≥100,000 CNY;and adverse events of antiretroviral drugs.The main reasons for PLWH’s WTP for antiretroviral drugs covered by medical insurance were that the drugs had fewer adverse events and were easier to administer.The main reasons for PLWH’s unwillingness to pay were financial difficulties and privacy concerns.Conclusion Nearly one-third of PLWH are willing to pay for antiretroviral drugs covered by medical insurance.In the future,PLWH with a high WTP can be guided to use these drugs.
