As the wind speed increased from 14 to 22 m·s−1, from a small density to a large density, the mean wind erosion modulus decreased from 68 to 17 kg·hm−2·h−1 for winter rapeseed, and 150 to 31 kg·hm−2·h−1 for winter wheat. Total wind-erosion of sediment transport of CK was 18.6 g·m−2 min−1, which was 16 and 31 times the mean value of winter wheat and winter rapeseed, respectively. “Winter rapeseed + ” replanting peanuts, potatoes, rice, seed melons and other crops generally increased the production value by 5–74% compared with wheat and corn intercropping, which was 98–255% higher than the traditional wheat single crop. Our results suggested that the suitable area for planting winter rapeseed in northern China was approximately 3.3 × 106 hm2, and in terms of the best economic and ecological effects, the appropriate density was 5 × 105 plants·hm−2 in northern China. Our results indicated that Chinese winter rapeseed was the best choice for preventing wind erosion and improving ecological and economic benefits in winter and spring in northern China; additionally, winter rapeseed has important impacts on agricultural sustainability in semi-arid and arid climates.Winter and early spring wind soil erosion have considerable impacts on ecosystems, human well-being and agricultural production in the low precipitation zones of northern China. Little is known about the impact of growing winter rapeseed on ecological cropping systems and the associated economic benefits in the wind erosion area. To explore the winter rapeseed cover effect, we conducted a field experiment in which we covered the soil with winter rapeseed, winter wheat and wheat stubble at different plant density levels and used the spring bare ground as the control (CK). The effects of wind erosion, the “winter rapeseed + ” multiple cropping system, and the economic benefits were compared. There was a large difference in the dry matter, the maximum water absorption, the maximum water storage, the soil evaporation and total wind erosion, the amount of sediment transported in the stratum and the wind erosion modulus. Among them, the mean wind erosion modulus of spring sowing bare land was as high as 490.9 kg·hm China has a large population and less arable land, and the major crops still need to be grown2. China is suffering from the most serious soil erosion in the world, with more than 30.7% of land classified as seriously degraded3. Arable land disappears at a rate of nearly 70,000 hm2 per year, and nearly one centimetre of topsoil is lost annually in the Loess Plateau of northern China5. In most areas of the Loess Plateau, crops are harvested once each year, and after harvest, the soil is barren for six to seven months6. During the non-growing season, snow covers the soil only in parts of north-western and north-eastern China. Additionally, due to the scarcity of suitable crop species or varieties that survive over winter, there is very limited cropland area covered by winter wheat (Triticum aestivum L.) during the winter season in north-eastern China7. Wind soil erosion is a major factor that contributes to soil erosion under this kind of cropping system8.The FAO-led Global Soil Partnership reports that 75 billion tonnes of soil or 10 million hm9. Studies have shown that has desertification affected 2.6 × 108 hm2, or 27.5% of China’s total territory. In 2004, the amount of land area affected by desertification was 1.7 × 108 hm2, which accounted for 18.1% of the total territory. The area of soil affected by wind erosion was 1.91 × 106 km2 in the late 1990s. In the northwest province of Xinjiang, 82% of the eroded soil area was caused by wind10. Wind erosion affected more than 40%  of farmland in the Hexi Corridor of Gansu Province11. In Northeast China, black topsoil erosion also affected 38%  of the total area12. The impact of wind erosion on the productivity of agricultural and terrestrial ecosystems has been well documented2. Soil erosion increases water runoff, thereby decreasing soil water infiltration and soil water storage capacity, causing a loss in organic matter and plant nutrients. It also affects the soil biota and overall biodiversity15. Regarding the off-site effects, wind erosion can accelerate the melting of glaciers and rise of snow lines16, increase dust pollution, and increase or decrease soil CO2 emissions through enhanced mineralization and sediment burial18.Wind-caused soil erosion is one of the major limiting factors affecting sustainable agriculture systems and ecological security in arid and semi-arid areas of northern China20. When 60% of the soil surface is covered by vegetation, it can minimize soil loss22. During the wind erosion season, sediment loss varies based on the crops present23. Compared to winter wheat and winter rye, alfalfa significantly decreases wind erosion24. There is also a positive correlation between wind erosion and wind speed. Soil-wind erosion can be reduced with a higher height of crop stubble after harvest27. When this method is used, however, the problems of operational, economic, and short-term land productivity constraints remain unsolved29. In northern China, there is a shortage of economically effective winter cover crops and winter cash crops, and winter wheat does not consistently overwinter in most areas of this region30. Even in areas where winter wheat can overwinter, it produces a small amount of vegetative mass by winter, resulting in limited soil coverage during winter and early spring; additionally, winter wheat has a maturation period similar to that of spring wheat with little or no economic benefit31. Winter rapeseed can produce nearly complete soil coverage and reaches physiological maturity approximately 30 d earlier than winter wheat, which could enable multiple crops to be grown in a single growing season, with substantial economic and ecological benefits compared to winter wheat and other winter crops. However, winter rapeseed production in northern China is constrained by its climate, annual extreme low temperature of −22.7 to −45.0 °C, negative accumulated air temperature of −700 to −1,612 °C in January, and mean low temperature of −11.1 °C in the coldest month; furthermore, there are least 150 to 180 days of winter33.Vegetative covers that protect soil loss are one of the principle parameters considered when simulating wind erosion processes35. The objectives of this study were to (i) compare soil wind erosion under different densities of winter rapeseed and winter wheat, as well as wheat stubble with spring sowing, in the Loess Plateau of northern China; (ii) assess the economic performance of winter rapeseed; and (iii) develop a basis and reference for the adjustment of crop structure to reduce wind erosion through winter rapeseed production.Since 1996, we have studied the over-wintering problems of winter rapeseed in northern China and have developed winter rapeseed varieties with extreme cold tolerance that are adapted to this area; these varieties could serve as winter cover crops to reduce soil wind erosion while providing additional ecological and economic benefits−5 and 8.77 × 10−5 g·m−2, respectively; the maximum water absorption increased by 8.99 × 10−5 and 6 × 10−4 g·m−2, respectively; the maximum water storage increased by 1.5 × 10−4 and 4.4 × 10−4 g·m−2, respectively; and the soil evaporation decreased by 28 and 4.1%, respectively. When the density of the cover treatments increased by one level beyond the second density level, the coverage of the soil surface increased by 15.1 and 20.1%, respectively; the cover of dry matter increased by 4 × 10−6 and 5.05 × 10−5 g·m−2, respectively; the maximum water absorption increased by 6 × 10−5 and 2.52 × 10−4 g·m−2, respectively; the maximum water storage increased by 9.74 × 10−5 and 1.83 × 10−4 g·m−2, respectively; and the soil evaporation decreased by 39 and 14%, respectively. When the density of the cover treatments was increased further, the degree of change for these indicators decreased. Among the cover treatments, the ranges of coverage of the soil surface, cover of dry matter litter and soil evaporation were largest for wheat stubble, the ranges of maximum water absorption and maximum water storage were largest for winter rapeseed, and the ranges in these indicators with winter wheat were intermediate. To increase the amount of cover of dry matter, thereby increasing the soil water storage and water absorption and effectively reducing the soil evaporation, the effect of returning to wheat in the same year was poor, and the winter wheat produced the least cover . Compared to spring Brassica rapa, spring Brassica napus, and flax, winter Brassica rapa increased the yield by 68, 73, and 144%, respectively, and the maturity time was earlier, thereby allowing other crops to be planted following its harvest. In contrast, flax produced the lowest yield and had the longest growth period.Winter gye Fig. . The winAcross several years and locations in northern China, the economic performance of “winter rapeseed+” annual double-crop and two-year three-crop crop production systems, winter rapeseed multi-cropped oil peanuts, oil sunflower, corn, rice, millet, oats, hazelnuts, seed melons, vegetables, and other crops and multiple varieties of sweet, bitter buckwheat, soybean, and green corn were evaluated Fig. . There w16. Due to the strong winds and low precipitation during winter and spring, the soil texture is loose, the surface coverage lacks vegetation, and the soil moisture content is low. The combined superposition of these unfavourable factors determines that spring is the season with a high incidence of wind erosion hazards in this area. From the dynamic trend of surface coverage and the trend of wind erosion, there are changes in the characteristics of “space-time dislocation”. That is, the most severe period of wind erosion is the season with the lowest coverage in winter and spring and the season with the weakest wind erosion resistance. The direct result of this “space-time dislocation” is soil wind erosion and major economic losses37. The research results showed that when farmland was covered with vegetation, such as winter rapeseed, winter wheat, and wheat stubble, the soil erosion by wind was significantly reduced, thereby reducing the loss of soil organic mass, soil nutrients, and soil biota and reducing the soil water evaporation43. Our previous results showed that overwinter rapeseed had the greatest effect on soil erosion by wind among the vegetation covers. The soil surface had a higher roughness and a threshold wind velocity, as well as a lower modulus of wind erosion and a lower soil transportation rate when covered with winter rapeseed43. Soil erosion by wind is also affected by other factors, such as the density or populations of cover crop or residues . Vegetation characteristics, such as density, stalk height, and diameter per unit soil area, determine the silhouette area where the wind must pass. When the silhouette area index was increased, wind speeds above the soil surface were reduced, and soil erosion by wind was decreased44. Compared with uncovered soil, there were significant increases in soil coverage, dry mass, soil water content with wheat stubble, different densities of winter wheat and winter rapeseed covered soil, and significantly reduced soil water evaporation and wind erosion  achieves a significant of a coverage effect as that of the 30 cm stubble. Our previous results showed that our best winter rapeseed varieties had an approximately 90 to 95% winter survival ratio; therefore, if planting with a density of 5 × 105 plants·hm−2, after winter, 4.5 × 105 to 4.75 × 105 plants·hm−2 plants survived. Our previous results also showed that for the best yield, the 4.5 × 105 to 5.5 × 105 plants·hm−2 was the optimal density in different regions of northern China40 , phosphorous (P), potassium (K), and organic matter at the experimental site were 0.83 g·kg−1 is >200 d, and the number of days of wind over 17 m·s−1 (level 8) is generally from 30 to 80 d. In this region, the standard practices are to produce one crop per year and maintain a bare soil surface with no or minimal crop residues or vegetation from harvest until planting.The Agricultural Experiment Station of Gansu Agricultural University is in Huangyang town, Wuwei, Gansu Province , located at the eastern end of the Hexi Corridor, China, from April 2007 through March 2012. The annual average temperature is 7.8 °C, the extreme low air temperature is −27.8 °C, the precipitation is 200 mm, and the evaporation is 2,600 mm. The annual wind speed >6 m·sBrassica rapa L. variety of Longyou-6 was planted on August 20 and had 4 treatment levels: 1.5 × 105, 3 × 105, 4.5 × 105, and 6 × 105 plants hm−2. The winter wheat variety of Aijiao-7 was planted on September 7 and had 4 treatment levels: 15 × 105, 22.5 × 105, 30 × 105 and 37.5 × 105 plants hm−2. When wheat is harvested, the height of the designed wheat stubble is kept at 30 cm for the winter. When there is no cover, planting occurs in late March of the following year. Among them, winter rapeseed and winter wheat returned to green in March of the following year. The amount of soil evaporation was determined by selecting the “S” type in the field43. The aboveground crops were taken in the field, and the cover rate [E = 830.14(8.20 × 10−5)VCR], where E is the wind erosion rate (g/min), VCR is the vegetation coverage or vegetation density]46. Maximum water absorption was the weight of the 1 m3 aboveground crops (winter wheat/winter rapeseed/wheat stubble) after it is soaked in water and fully absorbed], maximum water storage was the maximum water absorption minus the weight of the 1 m3 aboveground crops (winter wheat/winter rapeseed/wheat stubble), and the dry matter, soil evaporation of different density treatments could be determined48. Without destroying the surface structure, the soil samples of different treatments with a volume of 30 cm × 20 cm × 20 cm are measured in the soil sample box and brought back with plastic bags. With three replicates.In Huangyang towns of Wuwei city, the soil cover treatments were winter rapeseed, winter wheat, wheat stubble, and no cover (CK). After harvesting spring wheat, the land is ploughed. The winter 2, with three replicates. After maturity, each crop in each treatment was sampled, the plot yield was calculated, and the yield and economic benefit were compared48.According to the main planting methods in production, the test materials are winter rapeseed: Longyou-6, Longyou-8; corn: Zhengdan-958, Fu Nong-1, Shendan-16, Shendan-16, Xinyu-10, Xinqing-1, Chaotian-1, Liaodan-39, Liaodan-2; soybean: Hefeng-50, Chundou-1, 87U-72; sunflower: 5009, 5010, Xinkui-5; rice: Japonica (Longjing-20), glutinous (Nuoyou-2); wheat: Yongliang-4; flax: Zhangya-2; potato: Kexin-2; buckwheat: Pingqiao-3, K208-02, K208-06; oats: Baiyan-8; millet: Longgu-7, Longmi-5. The materials were provided by the Gansu Provincial Rapeseed Engineering Technology Research Center. This paper has 24 seeding modes: winter rapeseed-corn intercropping, winter rapeseed-feeding corn intercropping, winter rapeseed-soybean multiple cropping, winter rapeseed-oil sunflower multiple cropping, winter rapeseed-rice sunflower intercropping, winter rapeseed-potato multiple cropping, winter rapeseed-sweet buckwheat multiple cropping, winter rapeseed-bitter buckwheat multiple cropping, winter rapeseed-millet multiple cropping, winter rapeseed-vegetable multiple cropping, winter rapeseed-millet multiple cropping, winter rapeseed-seed melon multiple cropping, winter rapeseed-peanut multiple cropping, winter rapeseed-oat multiple cropping, wheat-corn intercropping, single cropping of frontage crops for rotation: corn, soy, potato, winter rapeseed, flax, wheat, spring rapeseed, and rice. The main intercropping method is wheat-corn intercropping with CK1, and the single wheat is CK2. The area of the plot is 18 m−1 (turbulence intensity < 0.4%) and measured using a pitot tube and a micrometre pressure gauge49.A wind erosion test was conducted at the Key Laboratory of Desert and Desertification of the Chinese Academy of Sciences. Wind erosion was assessed through tunnel tests. The wind tunnel had a total length of 37.8 m, a test length of 16.2 m, a cross-sectional area of 1.0 × 0.6 m, and smooth walls constructed of multi-layer plywood with glass windows. The wind speed within the wind tunnel was continuously adjustable from 2 to 40 m·s−1. Soil particles were collected at heights of 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 cm using a WITSEG sand collector . Sample boxes were weighed before and after wind erosion using an electronic balance to calculate the amount of wind erosion53. The wind erosion rate (Q) was calculated as the amount of wind erosion per unit time in the test conditions. The wind erosion modulus was calculated as the amount of wind erosion per unit area per unit time at a given wind speed55.The sample box was placed 12.1 m from the inlet of the test section, and the surface of the box was flush with the bottom of the wind tunnel. The point of the horizontal distance of the rapeseed plant height was set at 20 cm. Blowing lasted for 5–10 min at net wind speeds of 14, 18 and 22 m·sP ≤ 0.05.Data were analysed by SPSS 19.0 statistics software . The assumptions of normality and common variance were verified based on scatterplots of residuals versus predicted values. Treatment means were compared using Duncan’s multiple range tests. Statistical significance of differences was accepted at


With increasing interest in exposure effects across generations, it is crucial to assess the validity of information given on behalf of others.To compare adult’s report of their parent’s smoking status against parent’s own report and examine predictors for discrepant answers.n = 5307 (27-67 years) participating in the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) generation study. Information about parent’s smoking status during offspring’s childhood and mother’s smoking status during pregnancy was obtained by questionnaires from parents and their offspring. We calculated sensitivity, specificity and Cohen’s Kappa [κ] for agreement using parent’s own report as the gold standard. We performed logistic regression to examine if offspring’s sex, age, educational level, asthma status, own smoking status or parental status, as well as the parent’s sex and amount of smoking during childhood predicted disagreement.We studied 7185 offspring (18-51 years) and one of their parents, not having children was a predictor for discrepant answers (odds ratio [OR] 2.11 [95% CI 1.21–3.69]). Low amount of parents’ tobacco consumption, < 10 cigarettes/day (OR 2.72 [95% CI 1.71–4.31]) also predicted disagreement compared to ≥10 cigarettes per day, and so did offspring’s reports of fathers’ smoking status (OR 1.73 [95% CI 1.09–2.74]) compared to mothers’ smoking status. Offspring’s sex, asthma status, educational level, smoking status or age was not related to discrepant answers.The sensitivity for offspring’s correct report of parent’s smoking status during childhood (0-10 years) was 0.82 (95% CI 0.81–0.84), specificity was 0.95 (95% CI 0.95–0.96) and a good agreement was observed, κ = 0.79 (95% CI 0.78–0.80). Offspring’s report of mothers’ smoking status during pregnancy showed a lower sensitivity, 0.66 (95% CI 0.60–0.71), a slightly lower specificity, 0.92 (95% CI 0.90–0.95) and a good agreement, κ = 0.61 (95% CI 0.55–0.67). In multivariate logistic regression analysis, offspring Adults report their parent’s smoking status during their childhood, as well as their mother’ smoking status when pregnant with them, quite accurately. In the absence of parents’ direct report, offspring’s reports could be valuable.The online version of this article (10.1186/s12889-019-6414-0) contains supplementary material, which is available to authorized users. Smoking is a major cause of respiratory diseases  and infoIncreasing evidence suggests that exposures early in life influence subsequent health, and emerging evidence furthermore suggests that exposures even before conception, may influence the health of future generations , 8. WithA number of studies have examined offspring-reported parental information on history of somatic and mental diseases –11; howeThe objective of this population-based study is to examine the agreement of offspring-reported parental smoking status prenatally and during the offspring’s childhood, with mothers’ and fathers’ own self-reported smoking status. Furthermore, the study also aims to investigate predictors for discrepant answers in order to contribute to the field with knowledge of potential pitfalls in information given on behalf of others.www.rhinessa.net). One parent of each offspring in RHINESSA had previously participated in the Respiratory Health in Northern Europe (RHINE) study (www.rhine.nu), part of the European Community Respiratory Health Survey (ECRHS) initiated in 1989–1992 with three study waves (www.ecrhs.org) performed ten years apart. RHINE data was collected from seven different centres in five countries: Reykjavik (Iceland), Bergen (Norway), Umeå, Uppsala and Göteborg (Sweden), Aarhus (Denmark) and Tartu (Estonia). Furthermore, offspring with parents from three additional ECRHS centres, namely Melbourne , and Huelva and Albacete (Spain), were included in the RHINESSA population. Written consent was obtained from each participant in all study centres. In total, 8260 offspring from the RHINESSA cohort were matched with one of their parents (n = 6045). We used self-reported questionnaire information about smoking status from the parents themselves (collected in RHINE III/ECRHS III (2010–2012) or RHINE II/ECRHS II (1999–2000)) as well as offspring-reported parental smoking status , 2013–2016). Smoking during pregnancy was assessed from a specific women’s questionnaire in the RHINE III study. The questionnaires used have been developed in the framework of ECRHS, RHINE and RHINESSA and are used in several studies before. All questionnaires are available online from the study webpages listed above.The study population is from the RHINESSA generation study - Respiratory Health in Northern Europe, Spain and Australia (n = 5307 (27-67 years), obtained in prioritised order from either RHINE III, ECRHS III, RHINE II or ECRHS II with full information as the eligibility criterion. In the centres of Melbourne, Huelva and Albacete, all smoking data were assessed by interview-administered questionnaires while data from all other centres were mostly assessed by a self-administrated questionnaire.We used information from 7185 adult offspring (18-51 years) with information on one of their parents, n = 679).A flowchart of the study population is provided in Fig. Parental smoking status during offspring’s childhood was defined based on the parents’ date of birth, age of smoking debut or current age and number of years they had smoked (current smokers) or the year they had quit (ex-smokers). Offspring’s childhood was defined as the age period 0–10 years.A.Do you smoke? (this applies even if you only smoke the odd cigarette/cigar or pipe every week) (No/Yes)”, “Did you smoke previously? (No/Yes)”, “How old were you when you started smoking? (...years)”, “For how long have you smoked? (applies to both smokers and ex-smokers) (...years)”, and “If you are an ex-smoker, when did you stop smoking? Year ...”RHINE III: “B.Are you a smoker (this applies even if you only smoke the odd cigarette/cigar or pipe every week)? (No/Yes)”, “Are you an ex-smoker? (No/Yes)”, “Smoked for …years (applies to both smokers and ex-smokers)”, and “Stopped smoking in … (year)”RHINE II: “C.Have you ever smoked for as long as a year?  (No/Yes)”, “How old were you when you started smoking? (Years)”, “Do you now smoke, as one month ago? (No/Yes)”, “Have you stopped or cut down smoking? (No/Yes)”, and “How old were you when you stopped or cut down smoking? (Years)”ECRHS III and ECRHS II: “Parents’ report of their own smoking status during their offspring’s childhood was accessed slightly differently, do to slightly different questions, in the different surveys and study waves. The questions used were:RHINE III – Women’s questionnaire”, mothers’ report of own smoking status during pregnancy was identified through the question: “During this pregnancy (tick if yes)… Did you smoke?” The mothers’ report of own smoking status during pregnancy was dichotomized according to whether or not they smoked, and correct pregnancy (in case of siblings) was identified through offspring’s birth year.In the “Did your father ever smoke regularly during your childhood? (No/Yes/Don’t know)”, “Did your mother ever smoke regularly during your childhood? (No/Yes/Don’t know)”. Their mothers’ smoking status during pregnancy, on the other hand, was obtained through the question “Did your mother smoke when she was pregnant with you? (No/Yes/Don’t know)”. Offspring-reported parental smoking status during the offspring’s childhood and offspring-reported maternal smoking status during pregnancy was dichotomized as “Yes” or “No” and the “Don’t know” category was treated as missing data. For 2.3% of the fathers and 1.4% of the mothers, their offspring answered “Don’t know” to the question on whether they had smoked during the offspring’s childhood, while 23.1% of the mothers’ smoking status during pregnancy was categorized as “Don’t know” by the offspring.In the RHINESSA study, offspring-reported parental smoking status during the offspring’s childhood was obtained through the questions “A.“How much do you smoke / did you smoke?  grams/week…”.ECRHS III and II: Offspring’s sex, age, educational level, asthma status (self-reported doctor diagnosed asthma), own smoking status and own parental status were included as potential predictors for disagreement. Offspring’s sex was included in the model to examine sex differences in reporting of their parent’s smoking; age was included to examine the differences in time trends and risk of recall bias as a predictor for discrepant answers. Educational level was included to examine if the well-studied “health-education gradient” would be a predictor for awareness of parents’ health behaviour. Offspring own asthma status was included as we hypothesise children’s own asthma status will influence their recall of their parents smoking. Offspring’s own smoking status and parental status were included to examine if their own behaviour were increasing their awareness about their parents’ behaviour. Asthma, smoking status and own parental status were dichotomized as “No” or “Yes”. Offspring’s age was categorized as “< 25 years”, “≥25 < 35 years” or “≥35 years” (reference). Education was categorised as “primary school” (reference), “secondary school/technical school”, or “college or university”. Parents’ sex and average amount of smoking were also included in the analyses as predictors for disagreement. Parents’ sex was included in the model to examine any sex differences, where amount of smoking was included to examine if higher amount of smoking had increased the awareness among the offspring. Parents’ amount of smoking was obtained in the surveys based on the following questions:The different tobacco products were converted to cigarettes. One cigarillo was converted to three cigarettes, one cigar to five cigarettes, and one gram pipe tobacco equalled one cigarette . The amoSensitivity and specificity were calculated with 95% confidence intervals [CIs]. Cohen’s Kappa estimate [K], with 95% CIs, was calculated to estimate the agreement of the offspring-reported parental smoking status during childhood and pregnancy with the parent reported smoking status during the same periods. Parents’ own report was considered the gold standard. Cohen’s Kappa interpretation was based on the following categories: poor agreement, < 0.2; fair, 0.21–0.40; moderate, 0.41–0.60; good, 0.61–0.80; and very good, 0.81–1.00 p-value of < 0.05 (two-sided) and 95% CIs were calculated.Multivariate logistic regression models were conducted to estimate the odds ratio [OR] of whether offspring’s sex, age, educational level, asthma status, own smoking status or own parental status and parents’ sex and amount of smoking were predictors for disagreement. The regression models were performed with repeated measurements due to multiple offspring from the same parent using proc. GENMOD function in SAS. The model was mutually adjusted for the included variables and further adjusted for study centre. Disagreement was defined as discrepant answers between offspring and their parents. The significance level was set at a amount of smoking affected the sensitivity, specificity, or agreement. Further subgroup analyses were performed to examine whether false answers from the main analyses were false positives or false negatives. Additionally, sensitivity analysis with a reversed priority line  of the included data from the parents was performed to examine if the period of the data collection and perception of smoking at that time had an impact on the estimates. Separate analyses of centres were conducted for sensitivity, specificity and K, and adjustment for study centre was applied in the logistic regression models. All statistical analyses were performed using SAS  version 14.1.We performed sensitivity analyses where those excluded due to missing co-variables were included in the calculation of sensitivity, specificity and K. Furthermore, we performed sensitivity analyses where childhood was expanded to cover 0–18 years. We performed analysis by sex of the parents, and by the offspring’s own parental status. Subgroup analyses were conducted to examine if parents’ Baseline characteristics of the 7185 offspring and 5307 parents are presented in Table The sensitivity for correct offspring-reported parental smoking status during childhood (0-10years) was 0.82 (95 % CI 0.81–0.84), specificity was 0.95 (95 % CI 0.95–0.96) and a good agreement was observed κ = 0.79 (95 % CI 0.78–0.81) , specificity 0.95 (95% CI 0.95–0.96) and κ 0.79, (95% CI 0.77–0.80). When childhood was expanded to cover 0–18 years, similar results were also observed, sensitivity 0.82 (95% CI 0.80–0.83), specificity 0.96 (95% CI 0.95–0.96) and κ 0.79, (95% CI 0.77–0.80).Analyses by sex showed largely similar results with a slightly lower sensitivity 0.81 (95% CI 0.79–0.83) and κ 0.78, (95% CI 0.76–0.80) and similarly specificity 0.96 (95% CI 0.95–0.97) of the fathers compared to mothers, sensitivity 0.84 (95% CI 0.82–0.86), κ 0.80, (95% CI 0.78–0.82) and specificity 0.95 (95% CI 0.94–0.96), Additional file In subgroup analyses of parents’ smoking amount, the sensitivity 0.89 (95% CI 0.88–0.91) and κ 0.85, (95% CI 0.83–0.86) were increased when the parents had smoked more than 10 cigarettes per day during their offspring’s childhood compared to the main analysis and decreased if the parents had smoked less than 10 cigarettes per day, sensitivity 0.74 (95% CI 0.72–0.76) and κ 0.72, (95% CI 0.70–0.74). The specificities remained unchanged. Separate analysis of offspring and parental predictors for disagreement produced similar results as the main analyses with offspring and parental predictors in the same model.n = 511, 71%) compared to false positive answers , meaning that the parents had reported smoking more often than the offspring. Characteristics of offspring themselves who reported false negative answers were similar to the total study population except higher educational level (University/College 66% vs 60%), whereas offspring who reported false positive answers were slightly older and more often females (59% vs 58%), smokers (17% vs 12%), and asthmatics (18% vs 16%). Offspring who reported false negative were less likely to report regarding their mothers  compared to the total population, whereas offspring who reported false positive answers were more likely to report regarding their mothers . Parents’ mean age was slightly higher for offspring who reported false negative as well as false positive compared to the total population (54 and 55 vs 53 years).Further analyses of the 715 false answers in the main analysis showed a higher prevalence of false negative answers  compared to reports of their mothers’ smoking status during pregnancy (K = 0.61) could be that the offspring have more direct information available during their own childhood compared to during pregnancy where the offspring solely have the information from a second source; e.g. the mother herself or other family members. Of the offspring 23% reported “Don’t know” to the question of whether their mother smoked during pregnancy or not, compared to 2% of reports during childhood which also indicates a higher uncertainty for mothers’ smoking status during pregnancy. Another possible explanation is the mother’s shame that she was smoking during pregnancy and therefore incorrectly reported that she did not smoke during pregnancy. Still, offspring’s report of the mother’s smoking status during pregnancy is documented to be a useful proxy for the mother’s own report of smoking during pregnancy.To our knowledge, this is the first study to examine the agreement of offspring-reported parental smoking status in a general population of both mothers and fathers. The sensitivity, specificity and agreement for the mothers’ smoking status during pregnancy are roughly in line with findings of an earlier study  of daughThe offspring were more likely to give a correct answer regarding their mothers’ than their fathers’ smoking status, which may be explained by the fact that mothers in general spend more time with their children, especially in early life, and consequently the offspring are more aware of their mothers’ smoking status. A similar argument was used by the “National Heart, Lung, and Blood Institute - Family Heart Study” of offspring-reported parental history of chronic heart diseases and diabetes that demonstrated high agreement with parental self-reported history; however, a lower agreement for asthma and hypertension , where tA low amount of parental tobacco consumption predicted discrepant answers confirming the results of Simard et al. . The morWe found a quite high sensitivity and an even higher specificity indicating a low risk of misclassifying non-smokers, while the risk of misclassifying smokers is higher but still limited. In line with these findings, we could see a higher prevalence of false negative answers compared to false positive answers among the offspring which may be due to the increasing awareness of smoking and second-hand smoking’s negative influence on health , and parOffspring’s own parental status was shown to be a predictor for discrepant answers. A higher sensitivity and agreement was found among offspring with children themselves. These results could indicate that offspring with children are more aware of exposures in the past, and may start to ask their parents about their own childhood. Even though younger participants had a shorter recall period, the younger the offspring, the higher the odds ratio of discrepant answers, however, this was not significant. This could possibly be explained by the fact that perception of smoking has changed over time in society, e.g. greater knowledge about the harmful impacts of smoking on health  and pareUsing parents’ own self-reported information as the gold standard probably introduces a risk of underestimation of the true prevalence of smoking –4. The nIn our study, the analysis of the discrepant answers between offspring and their parents was primarily false negative answers. The underestimation of the offspring’s report in addition with the lack of a true gold standard  will enhance the risk of underestimating the true prevalence of smoking. A consequence is that smoking information given on behalf of others is not ideal if the purpose of a study is to determine prevalence of smoking, but it can be useful in investigations researching associations between smoking and diseases, even though some misclassification can be expected.A limitation of the study is that the wording for parents own report of smoking (which picks up a measure of “current” use) is different to the wording for the offspring-reported parental smoking (which picks up a measure of “regular” use), which is not identical concepts. For example, a parent who smoked very intermittently may consider themselves a smoker, but the offspring may not see this as regular use.We do not have information on whether the offspring who completed self-administrated questionnaires consulted their parents to provide answers about parental smoking. However, we are reassured by finding no clear evidence of difference from centre specific analysis. The measures of agreement from centres based solely on interview data   did not substantially differ from centres that collected data from self-administrated questionnaires, Additional file A major strength of our study is the large population-based RHINESSA population, which enabled us to examine both male and female offspring as well as both male and female parents from a general population. A further strength is the ability to determine predictors for discrepant answers based on the large amount of available information from both parents and offspring.This study demonstrates that adult offspring with good agreement reported their parents’ smoking status during their own childhood and their mothers’ smoking status during pregnancy compared to their parents’ own answer. Offspring’s own parental status, the amount of parental smoking as well as sex of the parents predicted disagreement while offspring’s own sex, age, educational level, asthma status, or smoking status did not influence the risk of discrepant answers. Our results suggest that in the absence of smoking information from parents themselves, offspring’s reports could be valuable.Additional file 1:Table S1. Sensitivity, specificity and Cohen’s Kappa estimate of smoking status during offspring’s childhood by sex. (DOCX 14 kb)Additional file 2:Table S2. Sensitivity, specificity and Cohen’s Kappa estimate of smoking status during offspring’s childhood by centre (DOCX 15 kb)


Sorbus L. fruits are determined by their unique composition of biologically active compounds. The aim of this study was to determine the composition of flavonoids, phenolic acids, anthocyanins, carotenoids, organic acids and sugars as well as the total antioxidant activity in fruit powders of 20 Sorbus cultivars. Chemical profiles of rowanberry fruit powders vary significantly. Cultivars ‘Burka’, ‘Likernaja’, ‘Dodong’, and ‘Fructo Lutea’ distinguish themselves with exclusive phytochemical composition and high antioxidant activity. Fruit powders from ‘Burka’, ‘Likernaja’ contain the highest contents of anthocyanins while fruit powder samples from ‘Fructo Lutea’ and ‘Dodong’ contain the highest levels of phenolic acids, ascorbic acid and the lowest levels of fructose. Fruit powder samples from ‘Dodong’ also contain the highest levels of β-carotene and sorbitol and the lowest levels of malic acid. Cultivars ‘Burka’, ‘Likernaja’, ‘Dodong’, and ‘Fructo Lutea’ could be selected as eligible raw materials for the preparation of rowanberry fruit powders.Rowanberries have been traditionally used in various processed foods. Scientific research demonstrates the pharmacological effects of  Sorbus L. and are widely distributed in the Northern hemisphere, extending to high northern latitudes [Sorbus hybrids with various Rosaceae members such as Crataegus L., Aronia (L.) Pers., Pyrus L., Mespilus Bosc ex Spach [Sorbus cultivars, is notably reduced when fruits are being picked very late in the autumn as the freezing reduces bitterness and astringency [The rowans (mountain-ashes) belong to the genus atitudes . Rowan tatitudes ,3,4,5. Ratitudes ,7,8. Sciatitudes , antioxiatitudes , antidiaatitudes  that areatitudes  Ascorbicatitudes ,15,16,17atitudes . Rowanbeatitudes ,17. Scieatitudes ,18,19. Oatitudes . The astex Spach ,21. The ringency . Freeze ringency ,23. Compringency .Sorbus cultivars and to elucidate the cultivars with particular phytochemical composition. The uniform growing conditions allow the phytochemical evaluations eliminating climatic and environmental impact. To the best of our knowledge, the phytochemical and antioxidant activity data concerning the fruits of certain rowanberry genotypes  have not been reported before.The aim of this comparative study was to determine the composition of flavonoids, phenolic acids, anthocyanins, carotenoids, organic acids and sugars as well as the total antioxidant activity in fruit powders of 20 Neochlorogenic, chlorogenic, cryptochlorogenic acids and dicaffeoylquinnic acid derivative were detected in all rowanberry extracts tested . The conSignificant variation in flavonol profile was determined, depending on the rowanberry cultivar . The triSeparated and identified compounds  formed specific profiles depending on the cultivar. Only cyanidin 3-galactoside was detected in all fruit powder samples (except ‘Fructo Lutea’) with the amounts varying up to 346-fold .Sorbus fruits varied within a wide range (up to 68 fold)   with theFructose, glucose and sugar alcohol sorbitol were detected in all fruit powder samples . Sucrose−1  of phenolic compounds in the rowanberry powder samples was performed . Four prS. aucuparia cultivars. The fruit samples of this cluster were distinguished by one of the highest total content of sugars and by the lowest total contents of organic acid, phenolic acids and flavonoids. The second cluster was comprised exclusively of Sorbus hybrids. The fruit powder samples ascribed to the second cluster accumulated the highest content of anthocyanins, sugars, and the lowest content of carotenoids and phenolic acids. The third cluster was comprised of fruit powder samples of Lombart’s hybrid , ‘Esseziani’ and ‘Rosina Variegata’. In the fruit powder samples of these cultivars one of the highest total content of flavonoids and one of the lowest contents of anthocyanins, carotenoids and sugars were determined. To the fourth cluster, only ‘Dodong’ was attributed, which distinguished by the highest total content of carotenoids, sugars, and one of the lowest total contents of flavonoids and organic acids. The fifth cluster was comprised exclusively from ‘Fructo Lutea’. The fruit powder samples of this cultivar were distinguished by the highest total contents of phenolic acids, organic acids and notable amounts of carotenoids.After hierarchical cluster analysis, the rowanberry fruit samples were grouped into five clusters . StatistSorbus fruits (rowanberries) are unique fruits with a rich composition of phytocompounds of various chemical origin [Sorbus fruits is emerging [Sorbus species and incorporating their fruits in food and pharmaceutical industries could address the consumer’s concerns over the safety and functionality of foods and health promoting supplements, as Sorbus plants are easily cultivated and are appropriate for areas with lower temperatures and poor soil environments [−1, however, the contents of neochlorgenic and chlorogenic acids in fruit powder samples from ‘Burka’, ‘Granatnaja’ and ‘Titan’ are lower than previously determined by Kylli et al. [Sorbus fruits [l origin ,8,12. Cuemerging , althougronments . The amoi et al. . Caffeoyi et al. . Chlorogs fruits  as they s fruits . The tots fruits  studies.s fruits , dyslipis fruits , improves fruits , reduce s fruits . −1 up to 104 mg·kg−1 [−1 [−1 of total carotenoids. The phytochemical composition is determined not only by cultivar, but also by geographic origin, growing conditions and other factors [Carotenoids in rowanberries are mainly composed of β-carotene and cryptoxanthin . Literat mg·kg−1 ,21. Mikukg−1 [−1 . Our res factors ,16,33. C factors . Certain−1) and ‘Granatnaja’ (3.19 ± 0.10 g·kg−1) [Organoleptic properties of fruits are mainly determined by volatile compounds, sugars, organic acids and their ratios. Their content is very important for the consumers with special requirements, as well as it affects processing techniques . Mikulic g·kg−1) . Malic a g·kg−1) .Sorbus cultivars contained ascorbic acid. ‘Fructo Lutea’, ‘Dodong’, ‘White Swan’ and ‘Kirsten Pink’ were the cultivars with ascorbic acid determined in a range of 1.42–2.20 g·kg−1 (DW). These cultivars might be regarded as a rich source of vitamin C, as compared to other fruits, known sources of vitamin C e.g., cranberries (1.34 g·kg−1 DW) [Ascorbic acid is regarded as the nutrient quality indicator during processing and storage. If the amounts of ascorbic acid is well-retained, the other nutrients could be retained in matrices with minimum losses, as well . It is ikg−1 DW) . Ascorbikg−1 DW) . Freeze Sorbus L. cultivars were grown in the northern region of Lithuania at the arboretum of Rūta Stankūnienė in Linkaičiai, Joniškis district (56°12′00″ N 23°28′41″ E). The region is in the temperate climate zone and the sub-region of Atlantic-European continental mixed and broad-leaved forests. Characteristics of climate region: the average annual temperatures 6.5–7 °C; the annual minimum and maximum temperatures −33 °C and +35 °C; the annual precipitation amount—560–700 mm; snow coverage in days—75–90; sunshine duration hours—1750–1850. The experimental orchard was not irrigated. Samples of ‘Esseziani’, ‘Alaja Krupnaja’, ‘Burka’, ‘Businka’, ‘Dodong’, ‘Fructo Lutea’, ‘Granatnaja’, ‘Kirsten Pink’, ‘Konzentra’, ‘Krasnaja Krupnoplodnaja’, ‘Likernaja’, ‘Miciurinskaja Desertnaja’, ‘Nevezinskaja’, ‘Pendula Variegata’, ‘Red Tip’, ‘Rosina Variegata’, ‘Rubinovaja’, ‘Sorbinka’, ‘Titan’, ‘White Swan’ were collected at full maturity stage determined by horticulturist based on fruit color, flavor, and firmness . Description of tested rowanberry species and cultivars are displayed in O--β-d-glucoside , isorhamnetin 3-O-rutinoside, cyanidin 3-O-galactoside, cyanidin 3-O-glucoside, cyanidin 3-O-arabinoside, β-carotene, ascorbic acid, malic acid, fructose, glucose, sorbitol, sucrose, xylose, calcium carbonate, BHT, hexane, potassium persulfate, 2,2-azinobis  diammonium salt (ABTS), Trolox were purchased from Sigma–Aldrich GmbH ; 99.8% trifluoracetic acid, chlorogenic acid, hyperoside, isoquercitrin, rutin, astragalin were purchased from Carl Roth GmbH ; 96.3% ethanol was purchased from Stumbras SC . Purified deionized water (18.2 mΩ/cm) was produced using the Millipore  water purification system. Analytical and chromatographic grade reagents were used for this study: acetonitrile, neochlorogenic acid, cryptochlorogenic acid, quercetin 3-v/v, and adjusted according to volume with 70% ethanol. The fruit powder samples were weighed each to 1.0 g (accurate sample) and were then placed into a conical flask with 12 mL of 70% ethanol and extracted in an Elmasonic P 120 H ultrasonic bath  for 10 min. The extraction procedures were repeated three times. The extracts were centrifuged for 5 min at 8500 rpm in a Biofuge stratos centrifuge  The extracts obtained were filtered through a paper filter into a 50 mL volumetric flask, hydrochloric acid was added up to 0.1% The fruit powder samples were weighed each to1.0 g (accurate sample) and were then placed into a conical flask with 15 mL of distilled water and extracted in an Elmasonic P 120 H ultrasonic bath for 10 min. The extraction procedures were repeated three times. The extracts were centrifuged for 5 min at 8500 rpm in a Biofuge stratos centrifuge and the extracts obtained were filtered through a paper filter into a 50 mL volumetric flask. All prepared extracts were filtered through a membrane filter with a pore size of 0.22 μm (Carl Roth GmbH).Carotenoids were determined by the method described by Hallmann et al., 2011 with some modifications . The fruQualitative and quantitative analysis of flavonols and phenolic acid, anthocyanins, β-carotene and organic acid were performed using a Waters 2695 Alliance system  equipped with a Waters 2998 photodiode array detector. Qualitative and quantitative analysis of sugars was performed using the Waters 2695 Alliance system equipped with a Waters 2424 evaporative light-scattering detector.Separation of flavonols and phenolic acid was performed according to the methodology described by Gaivelyte et al. ,41 usingv/v/v/v)). The gradient variation consisted of: 0–35 min—7–25% B, 35–45 min—25–65% B, 45–46 min—65–100% B, 46–50 min —100% B, 51 min—7% B. Eluent flow rate was 1 mL/min, and injection volume 10 μL. The column was temperature-controlled, maintained at 25 °C [Separation of anthocyanins was performed according to the methodology described in European Pharmacopoeia, 2016 using an ACE column . The mobile phase of the chromatographic method consisted of eluent A (0.05% formic acid) and B ) and B (0.25% trimethylamine in ethyl acetate). The gradient variation consisted of: 0–10 min—10–50% B, 10–20 min—50–90% B, 20–25 min—90% B, 25–26 min—90–10% B. Eluent flow rate was 1 mL/min, and injection volume 10 μL. The column was temperature-controlled, maintained at 25 °C.Separation of β-carotene was performed using an ACE column . The mobile phase of the optimized chromatographic method consisted of eluent A  column (300 mm × 8.0 mm). The mobile phase of the optimized chromatographic method consisted of 1 mM perchloric acid. Eluent flow rate was 1 mL/min, and injection volume 10 μL. The column was temperature-controlled, maintained at 60 °C. Separation of sugars was performed using a Shodex SUGAR SZ5532 (Showa Denko KK) column (150 mm × 6.0 mm). The mobile phase of the optimized chromatographic method consisted of eluent A (water) and B (acetonitrile). The gradient variation consisted of: 0–5 min—81% B, 5–20 min—81–70% B, 20–22 min—70% B, 23 min—81% B. Eluent flow rate was 1 mL/min, and injection volume 10 μL. The column was temperature-controlled, maintained at 60 °C. Nitrogen was used as the ELSD nebuliser gas (25 psi), tube temperature was set to 60 °C.Chromatographic peak identification was carried out according to the analyte and reference compound retention time, by comparing the UV absorption spectra of the reference compounds and analytes obtained with a diode array detector, as well as by applying UPLC-QTOF-MS analysis described in our previous study . CaffeoyThe specificity was determined based on the retention time of analyte and standard compound, UV spectra and spiking the sample. Contents of phenolic acids were calculated at a wavelength of 325 nm, while the contents of flavonoids were calculated at a wavelength of 350 nm. Contents of anthocyanins were calculated at a wavelength of 535 nm, contents of β-carotene were calculated at a wavelength of 450 nm, contents of organic acids were calculated at a wavelength of 210 nm. The spectrophotometric analysis was performed using a Spectronic Camspec M550 spectrophotometer .Determination of total carotenoid content. The absorbance of the extracts was measured at 450 nm. The content of carotenoids was calculated from the β-carotene calibration curve and expressed as β-carotene equivalents in µg/g DW of fruit.+ radical cation decolourization assay according to the methodology described by Re et al. [+ solution (absorbance 1.00 ± 0.005) was mixed with 20 μL of the ethanol extract of fruit powder. A decrease in absorbance was at a wavelength of 734 nm after keeping the samples for 60 min in the dark. Antioxidant activity was expressed as Trolox equivalents (TE) in µmol/g DW of fruit. Determination of antioxidant activity was performed using an ABTSe et al. . A volump < 0.05. The principal component analysis was performed. The adequacy of the data was ensured by using Bartlett’s test of sphericity and the Kaiser-Meyer-Olkin measure of sampling adequacy. Factors with eigenvalues greater than 1 were taken into account. Hierarchical cluster analysis was performed using the between group linkage method with squared Euclidean distances. The data were processed using Microsoft Office Excel 2010  and SPSS 20  software. The amount of phenolic compounds is expressed as a mean ± standard deviation (SD) of three replicates. The statistical data analysis was evaluated by applying the ANOVA with Tukey HSD post- hoc test. Significant different means were marked with different letters. Differences were considered statistically significant when The phytochemical profiles of rowanberries vary significantly and are cultivar-specific. On the basis of the determined chemical composition and antioxidant activity, rowanberry powders can be regarded as a rich source of health promoting substances—carotenoids, flavonoids, phenolic acids, anthocyanins, sorbitol and ascorbic acid. The phytochemical profiles covering the compositions of bioactive compounds of different classes could be used in authenticity tests detecting the adulterations with other types of fruits. Cultivars ‘Burka’, ‘Likernaja’, ‘Dodong’, and ‘Fructo Lutea’ distinguish themselves with exclusive phytochemical composition and high antioxidant activity, as well. These cultivars could be selected as suitable raw materials for preparation of rowanberry fruit powders. Qualitatively prepared rowanberry powders with comprehensively defined phytochemical composition could be applied in the production of smart and innovative nutraceuticals or functional food ingredients.


Negative refraction has generated much interest recently with its unprecedented optical phenomenon. However, a broadband negative refraction has been challenging because they mainly involve optical resonances. This paper reports the realization of broadband negative refraction in the visible spectrum by using vertically-stacked metal-dielectric multilayer structures. Such structure exploits the characteristics of the constituent metal and dielectric materials, and does not require resonance to achieve negative refraction. Broadband negative refraction (wavelength 270–1300 nm) is numerically demonstrated. Compared to conventional horizontally-stacked multilayer structures, the vertically-stacked multilayer structure has a broader range of working wavelength in the visible range, with higher transmittance. We also report a variety of material combinations with broad working wavelength. The broadband negative refraction metamaterial provides an effective way to manipulate light and may have applications in super-resolution imaging, and invisibility cloaks. Super-resolution imaging4, negative index materials (NIMs)7, invisibility cloak9, perfect absorbers12, artificial chirality14, and electromagnetically induced transparency15 are examples of metamaterial applications that have properties beyond the limits of natural materials. Hyperbolic metamaterials (HMMs) show distinctive characteristics such as negative refraction17, sub-wavelength imaging20, confining the electromagnetic field21, and thermal emission23.Metamaterials composed of nanostructures of artificial atoms have shown many extraordinary properties that cannot be found in natural materialsε and permeability μ cannot be negative simultaneously, but if a certain material has negative values of both ε and μ24, the refractive index n becomes negative. The conventional materials with positive refractive index n have a positive value of the angle of refraction θ2 according to Snell’s law:In natural materials, permittivity θ2; i.e., negative refraction. The first NIM was achieved using split-ring resonators (SRRs), which have both negative ε and negative μ25. The negative ε is obtained by conducting wires below the plasma frequency ωP, and negative μ occurs near the resonance frequency ωSRR of SRRs. If ωP > ωSRR, then ε and μ are simultaneously negative in a certain region. Multilayered fishnet structure7, chiral structure28, and asymmetry nanorings structure29 have been studied to achieve negative n. NIMs have provided the possibility of applications such as super-resolution imaging and invisibility cloaks.In contrast, NIMs show a negative 31 have some drawbacks. The materials require optical resonance to obtain a negative μ; this requirement restricts the range of working wavelength ΔλW to a narrow region near the resonance and causes high resistive loss. As a consequence, development of practical applications has been obstructed. However, electrostatic and magnetostatic fields can be decoupled in electrostatic limits, in which a system has smaller dimensions than the wavelength6. Therefore, under transverse magnetic (TM) polarized light, the electromagnetic behaviors in such system are only relevant to the permittivity. The HMMs consist of constituents with sub-wavelength dimensions, so negative refraction under TM polarized light can be achieved in HMMs by simply manipulating ε even if they do not have negative n.Conventional metamaterials for NIMs34 . Such structure use an optical resonance to attain negative refraction; this requirement narrows ΔλW and causes high resistive losses. However, realization of a broad ΔλW and low-loss requires that resonance be avoided. Therefore, in this paper, we present vertically-stacked metal-dielectric multilayer structures  to achieve broadband negative refraction. This structure does not require any resonance to realize negative refraction and therefore it has a broad ΔλW that includes the visible range without additional losses due to resonance. The dispersion relation of HMMs was derived using effective medium theory36 (EMT) and using this relation, the ΔλW of negative refraction and transmittance of the vertical HMMs and horizontal HMMs are compared. We also suggest various vertical HMMs composed of different metal and dielectric materials. Plots of working wavelength and filling ratio of several metals with fixed dielectric show broadband ΔλW in the vertical HMMs.So far, the negative refraction obtained from HMMs has mainly been shown with horizontally stacked metal-dielectric multilayer structureskx, ky, kz are directional wavevectors in the medium, k0 is a wavevector in vacuum, ω is the frequency of the wave, c is the velocity of light in vacuum, εzz). An isotropic medium with the same permittivity in all direction has a spherical isofrequency surface, which shows the isotropic behavior of propagating waves , εd is the permittivity of dielectric, and εm is the permittivity of the metal. With the effective permittivity, Eq.  and the causality theorem  to calculate transmittance.Supplementary Information


The observed ferromagnetism upon doping arises from a Dirac  band in a non-ideal Lieb lattice with strong electronic inhomogeneity (EI) rather than the topological flat band in an ideal Lieb lattice. The EI, as characterized with a large on-site energy difference and a strong dimerization interaction between the corner and edge-center ligands, quenches the kinetic energy of the usual dispersive Dirac band, subjecting to an instability against spin polarization. We predict an even higher spin density for monolayer sp2c-COF to accommodate a higher doping concentration with reduced interlayer interaction.Lieb lattice has been extensively studied to realize ferromagnetism due to its exotic flat band. However, its material realization has remained elusive; so far only artificial Lieb lattices have been made experimentally. Here, based on first-principles and tight-binding calculations, we discover that a recently synthesized two-dimensional  sp2 covalent-organic framework, its origin remains unclear. Here, by first-principle and tight-binding calculations, the authors identify the Lieb-lattice-like feature of the two-dimensional covalent-organic material and the Stoner mechanism responsible for its magnetic behavior.While ferromagnetism has been observed in an  More recently, it has been further predicted to hold intriguing optical, electronic, and magnetic states8. Using photonic, cold-atom, and surface patterning techniques11, several artificial Lieb lattices have been made experimentally. However, a material realization of Lieb lattice has remained elusive, making some of the aforementioned properties inaccessible, such as Lieb-lattice ferromagnetism.Lieb lattice, i.e., a two-dimensional (2D) edge-centered square lattice Fig.  is one o14. More recently, organic magnetic materials have attracted increasing attention for their high spin-wave stiffness, weak spin–orbit coupling, and weak hyperfine coupling, which are appealing properties for spintronic device applications18. Generally, organic magnetic materials involve transition metal (TM) elements, which give rise to magnetic features due to their partially occupied and highly localized d or f orbitals. However, most organic materials contain only light elements without TM, such as covalent-organic frameworks (COFs)20.On the other hand, achieving ferromagnetism in organic materials has been an active subject for both fundamental interests in organic magnetism and practical applications as permanent magnets supplementary to their inorganic counterparts22, as well as newly predicted exotic electronic properties like Dirac and topological states27. Not surprisingly, efforts have also been made to induce magnetism in COFs; nevertheless, this has been a formidable challenge, because of their tendency to pair all valence electrons through strong covalent bonds to prevent the formation of unpaired spin-polarized electrons. Therefore, it is very surprising and exciting to see the most recent experimental observation of ferromagnetism in a two-dimensional (2D) sp2 carbon-conjugated COF (sp2c-COF) with high spin density28. However, its physical origin is completely unknown. This has motivated the present theoretical study, which surprisingly leads to our discovery of the first material system (the sp2c-COF) realizing a Lieb-like lattice and its Stoner ferromagnetism. This is clearly different from those exotic mechanisms30 proposed before for materials comprised exclusively of light elements, such as the flat bands in ideal 2D Lieb and Kagome lattices31. It also differs from systems with default-localized states with a strong Columbic repulsion , such as the localized orbitals33 in organic compounds36 and nano-carbon structures40. Apparently, it is also different from magnetism induced by external electrical or magnetic fields43.COFs have been extensively studied for their well-known promising applications in gas storage and separation, catalysis, and sensingsp2c-COF represents a kind of Lieb lattice (Lieb-3) with “ideally” one flat band sitting between Dirac bands, arising from the edge-center and corner states, respectively. Distinguished from an ideal Lieb lattice, however, sp2c-COF is coupled with a high degree of electronic inhomogeneity (EI), characterized by a large variation of on-site energy on different lattice sites. By mapping the DFT calculated band structure onto the Lieb-3 TB model, the EI is quantified with a large on-site energy difference and a strong dimerization interaction between the corner and edge-center sites. Consequently, the original dispersive Dirac  band in an ideal Lieb lattice becomes highly localized, subjecting to an instability against spin polarization upon hole doping. Consistent with experiments, we show that the nonmagnetic insulating sp2c-COF becomes a ferromagnetic (FM) metal upon iodine doping, and the generated magnetization is confined on the corner pyrene ligands. Furthermore, we predict that an even higher spin density can be realized in monolayer sp2c-COF, as the interlayer interaction is eliminated to make the valence band more localized.Based on density functional theory (DFT) calculation and tight-binding (TB) modeling, we discover that the E, the dimerization interaction δ between the corner and the edge-center sites, the nearest-neighbor (NN) hopping t, and the next-NN (NNN) hopping t′, as indicated in Fig. E, δ, and t′ all equal to zero, the band structure is characterized with Dirac cones formed at the M point, intersected by a flat band, as shown in Fig. t′ is known to affect the band dispersion along Γ-X/Y direction6, which is usually rather small and negligible. On the other hand, the ΔE and δ are known to suppress the dispersion of the Dirac bands significantly and lift the band degeneracy at the M point  from the other bands, and a non-zero δ term fully separates the three bands  in the inset of Fig. N) of sites on edges, and all lead to similar band structures, i.e., Dirac bands intersected by flat bands  lattice, where 2N + 1 is the number of sites per unit cell. Apparently, Fig. N = 1.Specifically, a positive/negative Δsee Fig. . Althougsp2c-COF  and 1,4-bis(cyanostyryl)benzene (BCSB) ligands, as highlighted by blue and red ellipses, respectively. Therefore, from the structural point of view, one may consider the sp2c-COF, Py(BCSB)2, to be described by a slightly distorted Lieb-3 lattice. To confirm this, we then carry out an electronic band matching analysis. In Fig. 2 in the kz = 0 plane. Clearly, the intrinsic Py(BCSB)2 is a nonmagnetic insulator, and the band gap is found to be around 1.0 eV , which is smaller than the experimentally measured 1.9 eV28. This is reasonable as gap size is known to be underestimated by the standard DFT method, which, on the other hand, can reasonably capture the dispersions and orbital compositions of both valence and conduction bands. Therefore, to save time we will use the standard DFT method, as the gap size will not affect our main conclusions about magnetic properties. We note that there is also a noticeable dispersion along the kz direction, indicating strong interactions between the layers 2 is understandable, because a large ΔE is expected between the molecular orbitals (MOs) of Py and BCSB ligands and a non-zero δ is expected from the structural distortion of the Py(BCSB)2 compared with the ideal Lieb-3 lattice. These results strongly suggest that the valence bands are derived from a non-ideal Lieb-3 lattice. In addition, based on the same analysis, we found that the bottom five conduction bands (CBs) above the Fermi level are the Lieb-5 bands  below the Fermi level, which are actually consistent with Lieb-3 bands, i.e., one nearly flat band in between two Dirac bands, albeit highly perturbed by EI. To reveal this, we calculate the band-resolved charge distribution for these three bands 228. The wavefunctions of the highest occupied MOs (HOMOs) of Py 2 are formed by different MOs and separated distinctly in the energy space, they can be independently reconstructed by a three- and five-band TB model on the Lieb-3 and Lieb-5 lattice, respectively. We then adjust the ΔE based on the energy diagram calculated for MO analysis, and fit the DFT calculated bands with different t and δ  is rather small, which is caused by a large separation between the HOMOs of Py and BCSB ligands. More importantly, we found relatively a large on-site energy difference (ΔE ≈ t ≈ 0.14 eV) and a strong dimerization interaction (δ ≈ 0.3t ≈ 0.04 eV) between the two HOMOs, indicating a high degree of EI, giving rise to a very narrow bandwidth (W ≈ 0.36 eV). Consequently, the upper Dirac band becomes highly localized and is fully isolated from the two bands below. We then compared our TB fitting parameters with those of the Wannier fitted Hamiltonian, which shows a very good agreement, further confirming the strong EI effect to induce a localization of the VB sp2c-COF to be a Lieb-lattice-like system, we now proceed to explain the physical mechanisms underlying the experimentally observed magnetic behaviors of the sp2c-COF upon iodine doping. It is well known that a Lieb lattice can spawn intriguing magnetic properties associated with the exotic flat band2. However, the flat band in Py(BCSB)2 is the second VB, which is beyond the reach of typical doping level. Therefore, one must look for a distinct mechanism. We realize that based on Stoner criterion45, the ferromagnetism can arise from any localized band under partial filling. A closer look at the first VB of Py(BCSB)2 reveals that this usual dispersive Dirac band has become highly localized due to the strong EI. Because the VB is made of 2p state, the Stoner parameter is in fact even larger than the 3d state46. Consequently, one may expect that this band will now be subjecting to an instability against spin polarization upon hole doping. To confirm this, we carry out a computational experiment to dope the system with one hole per unit cell, and calculate the corresponding electronic and magnetic properties.Knowing the 2 becomes metallic after doping , giving rise to an itinerant FM state. From the difference of charge distribution before and after doping  using iodine vapor28. Therefore, besides the computational experiment of hole doping, we perform calculations of the Py(BCSB)2 with iodine doping using several representative structural configurations. To decouple the iodine ions between the layers, we construct a two-layer supercell with one iodine. This gives a comparable doping concentration (0.5 hole per unit cell) with the experiments (0–0.7 hole per unit cell)28. The off-corner site is found to be the most stable position 2 is found to be FM and the corresponding spin distribution plot is shown in Fig. p orbitals. We have also examined another two structural configurations with the iodine sitting at the off-edge-center and corner site that has ~0.04 and ~0.36 eV per supercell higher energy, respectively, showing similar magnetic behavior ion Fig.  after ex45. Recall that there is a noticeable dispersion along kz direction in the band structure of bulk Py(BCSB)2 2, and its three key properties, i.e., bandwidth (W), spin splitting (J), and the highest magnetization are listed in Supplementary Table W of the Dirac band is much smaller than that of bulk Py(BCSB)2 and the J is significantly enlarged, which result in a much higher magnetization upon hole doping 2. This is possibly because a limited amount of iodine can be doped into the bulk sample with relatively a small surface area. To increase the doping concentration, one may use a thinner or monolayer Py(BCSB)2 with higher surface-to-volume ratios, leading to enhanced magnetization. To test these ideas, we suggest experiments to further study the magnetization of sp2c-COF as a function of doping level and film thickness.Another interesting point is that the magnetization of a flat or highly localized band depends critically on band filling. Therefore, it is natural to anticipate the magnetization to change with different doping level. We have calculated the magnetization for both bulk and monolayer Py(BCSB)28. Our calculations show similar band structure and magnetic behavior upon hole doping for C=N-COF, but interestingly, a stronger magnetic response than the monolayer Py(BCSB)2 , synthesized by the same group, also shows similar but weaker magnetic responsesp2c-COF is a material realization of a Lieb-like lattice. Furthermore, we demonstrate that it is a non-ideal Lieb lattice with strong EI, so that it exhibits an insulator-to-metal transition and a nonconventional magnetic instability, consistent with experimental observation. Our findings open the door to exploiting the highly tunable COFs as a versatile material platform to explore exotic electronic and magnetic properties hosted by Lieb lattices. Moreover, the Stoner mechanism for ferromagnetism provides a useful theoretical guidance in search of new COF-based organic magnets. The advancement in fundamental knowledge enabled by our theoretical study may also be transferred to technological applications for COFs as electronic and spintronic materials, beyond the already-known traditional applications as structural materials. Our work may also foster new research directions to study other exotic physics of Lieb lattices beyond magnetism in COFs, such as topological properties.In conclusion, we have discovered that the experimentally synthesized 2D organic system of 47, as embedded in the Vienna ab initio simulation package code48. All the calculations were performed with a plane-wave cutoff energy of 500 eV. For the sp2c-COF, we adopted the experimental lattice constants and transferred to the primitive cell with a = b = 24.74 Å, c = 3.73 Å, α = β = 100.09°, and γ = 91.69° [full structural relaxation would only change the lattice constants negligibly (<0.1%)]. For C=N-COF without available experimental results, the structure was fully relaxed, giving rise to lattice constants of a = b = 24.44 Å, α = γ = 90.00°, and β = 99.31°. To eliminate the interlayer interaction, we introduced a vacuum layer of 20 Å thickness for monolayer calculations. Both sp2c-COF and C=N-COF are reported to have AA stacking experimentally, which will be used for our study of both bulk and bilayer systems. The geometric optimizations were performed without any constraint until the force on each atom is <0.01 eV∙Å−1 and the change of total energy is smaller than 10−4 eV per unit cell. The Γ centered Brillouin zone k-point sampling was set with a spacing of 0.03 × 2π∙Å−1, which corresponds to 3 × 3 × 11, 3 × 3 × 5, 2 × 2 × 11, and 3 × 3 × 1 k-point meshes for bulk unit cell, 1 × 1 × 2 bilayer supercell, 49 with the B3LYP functional50. The computational experiment of hole doping was performed by changing the total number of electrons of the system while maintaining the charge neutrality with a compensating homogenous background charge. Simulations of Py(BCSB)2 with iodine doping were carried out using several representative structural configurations, e.g., corner and edge-center sites. To decouple the iodine ions between the layers, a two-layer supercell with one iodine was applied. Spin–orbit coupling effect of iodine is tested to have negligible effect.Our first-principles calculations were carried out within the framework of the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA)Supplementary InformationPeer Review File


In contrast to such work focusing on women’s experiences as targets of discrimination or men’s role in preserving inequality, we propose a solidarity-based approach that positions men and women as agents of change. This approach relies on two processes: leadership processes – particularly leadership as a form of influence based on shared identities among leaders and followers ; and political solidarity as a way to mobilize the silent majority (men) to work as allies beside a minority (women) and embrace equality as a common cause for both groups. In two experiments  we studied how leader gender and message framing affect men’s and women’s support for equality by contrasting a solidarity-based framing of gender equality as a common cause for men and women, with a women’s issue frame (Experiment 1) or a meritocratic frame (Experiment 2). The statement was attributed to a male or female leader (Experiments 1–2) or, additionally, to a government agency (Experiment 1). Women reported higher sense of common cause (Experiment 2) and collective action intentions than men (Experiments 1–2), and higher intentions under common cause compared to meritocracy frames (Experiment 2). Interestingly, male leaders invoked higher sense of common cause and collective action intentions for both men and women regardless of framing (Experiment 2). Irrespective of leader gender however, as predicted common cause framing boosted perceived leader prototypicality, legitimacy, and influence across the board (Experiments 1–2). Yet this was qualified by women (compared to men) rating leaders as more legitimate and influential under common cause compared to meritocracy framing (Experiment 2). Women’s reactions to equality messages, and the intersection of leadership and solidarity toward equality are discussed.Social psychologists have not fully investigated the role of leadership in mobilizing widespread support for social change, particularly gender equality. The burden of achieving gender equality is typically placed on women  – the main targets of such inequality. Traditional approaches frame workplace gender equality as either a  The burden of achieving gender equality has traditionally been placed on women , who are usually the main targets of such inequality . Typicaland men  followers’ shared social identity . This soand women’s collective action intentions. However, while women were mobilized by both male and female leaders, men were mobilized primarily by male leaders who espoused a common cause message . This research demonstrates that not only does it matter what is being said , but also who is saying it  and to whom  equality leaders might mobilize support for gender equality , they violate communal expectations of women and face backlash effects  to examine whether the gender of the leader affects their capacity to mobilize support for equality, as extant literature suggests e.g., . In ExpeIn line with N = 480, 240 women), between 17 and 68 years . They were recruited online via Facebook or Reddit (72%), or the university’s research participation program (28%). The results did not differ between these groups. Participants comprised 44% Australians, 35.8% Americans, 5.4% Canadians, 5.2% English, and 9.6% other. They were employed on a full- (33.5%), part-time (18.5%), or casual (17.9%) basis, or identified as unemployed (26.76%) or other (3.3%). Sixty-one percent were studying full- (50.2%) or part-time (8.8%) domestically, or full-time internationally (1.7%), with the remaining 39% not currently studying. The study was a 2  × 3  × 2  factorial design, with equal numbers of men and women being allocated at random to one of six conditions.Participants were students at a large Australian university or members of the general public  the minimum sample to detect a small effect size of f = 0.151) using a 2 × 3 × 2 ANOVA is 422 (35 participants per cell). We increased this to 480 (40 per cell) to reach sufficient power after the anticipated exclusion of participants who failed the leader gender manipulation check. Sensitivity power analyses revealed that our actual obtained sample size (338) had the power to detect effect sizes of: f = 0.152) for the participant gender and message framing main effects and participant gender × message framing interaction, and f = 0.169) for the leader gender main effect and all remaining two- and three-way interactions.An effect size of approximately f 0.0225 . Thus anParticipants completed a 15-min online questionnaire containing the experimental manipulations and dependent measures described below , and the group’s progress toward their goal in an annual report . Leader gender  was manipulated by changing the Commission[er]’s name  and using relevant pronouns . Message framing  was manipulated via equality group name  and message content . The Commission[er] communicated their pledge “to serve the [men and] women of this world” and stated their group “builds on the excellent work of all those [men and] women currently committed to achieving gender equality.”All measures used 7-point Likert scales . To assess the manipulation’s success, participants identified the Commission[er]’s gender , and rated the extent to which the vignette provided information regarding inequality being (a) a women’s only issue or (b) a common cause for men and women.Eight items (α = 0.95) measured participants’ collective action intentions supporting gender equality (adapted from Five items (α = 0.85) measured participants’ perceived prototypicality of the leader .Four items measured the leader’s perceived influence . Participants who failed to correctly identify the leader’s gender were excluded from further analyses, bringing the final sample to 338 (167 women). Participant exclusion distribution rates did not differ significantly by condition , and are reported alongside final participant gender distributions for each cell in Table Participants in the women’s issue conditions were significantly more likely than participants in the common cause conditions to agree that the article discussed “The need for women alone to stand up for equality” and “Inequality being a women’s only issue”  and are reported below in Table Participants in the meritocracy conditions were significantly more likely than those in the common cause conditions to agree that the article discussed “Women in senior management roles showing it’s possible to move up the leadership ladder by working hard” and “The idea that all individuals can succeed in the workplace irrespective of their gender, as long as they work hard” [F = 176.954, p < 0.001, Table Hypothesis 1a predicted that men and women would report higher collective action intentions and sense of common cause under common cause compared to meritocracy message frames. Providing partial support for this hypothesis, women (but not men) reported higher intentions (but not sense of common cause) under common cause framing. Additionally, Hypothesis 2 was not supported, which predicted that men would report higher intentions and sense of common cause under male leaders who promoted a common cause message. Instead, men reported significantly higher collective action intentions and sense of common cause under male  leaders irrespective of message framing. Importantly, women also reported higher intentions and sense of common cause under the same conditions.commoncause = 4.78, SD = 1.72; Mmerit issue = 4.55, SD = 1.50; F = 1.78, p = 0.185, women = 5.13, SD = 1.46; Mmale = 4.28, SD = 1.61), F = 26.404, p < 0.001, Contrary to Hypothesis 1a, no significant main effect of message framing was found, with participants instead expressing similar collective action intentions irrespective of how the message was framed [MF = 7.322, p = 0.008, F = 0.342, p = 0.560, and women would report higher intentions under common cause frames), only women reported higher intentions under common cause  compared to meritocracy frames . Alternatively, contrary to Hypothesis 1a, men expressed similar  collective action intentions regardless of how the equality message was framed .Simple effects performed at both levels of participant gender revealed a significant main effect of message framing for women, F = 0.480, p = 0.489, M = 4.86, SD = 1.60) compared to when female leaders did , F = 4.816, p = 0.029, and female participants. All remaining main effects and interactions were non-significant, all F ≤ 1.766, ps ≥ 0.185, Finally, absence of a significant three-way interaction failed to provide support for Hypothesis 2 which predicted that men would report higher intentions under male leaders who promoted a common cause message, commoncauseM = 5.25, SD = 1.68; merit issueM = 5.09, SD = 1.43; F = 0.65, p = 0.419, No significant main effect of message framing was found, thus failing to support Hypothesis 1a. Instead, participants reported similar sense of common cause regardless of how the message was framed [ = 0.899, p = 0.344, and women reported significantly higher sense of common cause under male leaders  than female leaders [M = 5.00, SD = 1.65; F = 4.429, p = 0.036, M = 5.78, SD = 1.17) expressing higher sense of common cause than men , F = 63.457, p < 0.001, F ≤ 3.279, ps ≥ 0.071, Absence of a significant three-way interaction again failed to support Hypothesis 2 which predicted that men would report higher sense of common cause under male leaders promoting a common cause message, Supporting Hypothesis 1b and replicating Experiment 1’s significant findings, participants evaluated leaders as being significantly higher in leader prototypicality, legitimacy, and influence when they promoted gender equality as a common cause rather than a meritocratic issue. However, this was qualified by an interaction showing that women in particular rated leaders as significantly more legitimate and influential under common cause compared to meritocracy framing.Consistent with Hypothesis 1b, leaders who promoted equality as a common cause  were evaluated as being significantly more prototypical of the gender equality movement than leaders who used meritocratic explanations for inequality , F = 65.527, p < 0.001, commoncause = 5.39, SD = 1.19; Mmerit issue = 5.08, SD = 1.36). No other main effects or interactions were significant, all F ≤ 1.389, ps ≥ 0.239, Consistent with Hypothesis 1b, a significant main effect of message framing showed that leaders who employed common cause framing  were viewed as significantly more legitimate than leaders who relied on meritocracy framing , F = 28.006, p < 0.001, M = 4.98, SD = 1.29) were considered significantly more influential than those who promoted it as an issue pertaining to meritocracy , F = 14.347, p < 0.001, F = 3.857, p = 0.050, F = 13.932, p < 0.001, F = 2.028, p = 0.156, M = 5.11, SD = 1.39) rather than an issue of merit . Again reflecting our leader legitimacy findings, men perceived leaders as being equally influential regardless of how they promoted equality .Supporting Hypothesis 1b, and replicating our prototypicality and legitimacy findings, leaders who promoted gender equality as a common cause  to better determine whether they differ in their capacity to mobilize individuals toward gender equality. Supporting Hypothesis 1b and replicating Experiment 1’s findings, participants again evaluated leaders as being significantly more prototypical, legitimate, and influential under common cause rather than meritocratic framing. However, this finding was qualified by an interaction which showed that women (but not men) evaluated all leaders as being significantly more legitimate and influential when they promoted common cause instead of meritocracy frames. These findings are addressed in the section “General Discussion.”and women) expressed higher collective action intentions and higher sense of common cause under male leaders compared to female leaders. This indicates that male leaders were more successful than female leaders at mobilizing male and female participants. However contrary to Hypothesis 2 this effect was not enhanced under common cause messages. These findings are discussed below.Another key aim of Experiment 2 was to examine how manipulating the perceived legitimacy of gender inequality affects men’s and women’s responses to the issue, by contrasting common cause framing with meritocratic framing. Replicating Experiment 1’s significant findings, women reported significantly higher collective action intentions than men, and the same pattern was found for women’s sense of common cause with the women affected by inequality. While Hypothesis 1a was not supported in Experiment 1, in the current experiment women reported significantly higher collective action intentions (but not higher sense of common cause) under common cause compared to meritocracy message frames. Meanwhile, men’s mobilization remained unaffected by message framing. Therefore, despite all participants evaluating leaders who promoted common cause frames more positively, Hypothesis 1a was partially supported for women, but not men, and only for collective action intentions, not sense of common cause. Additionally, in regards to Hypothesis 2, men  strengthened the effects of such framing on (women’s) mobilization. One limitation is that including a third women’s issue condition would have allowed us to better determine the effects of common cause framing relative to meritocratic framing. Nevertheless, these results indicate that women, as the primary targets of gender inequality  are cracked” , p. 371.e group” , p. 118.and women and thus craft a sense of common cause and shared identity, both men and women appear more favorable toward, and receptive of, these equality leaders.This paper extends what is being said, compared to who is saying it: message framing did not affect men’s mobilization in either experiment, but in Experiment 2 they  reported higher collective action intentions and sense of common cause under male leaders – irrespective of how they framed the issue. However, because this effect was not enhanced under common cause messages, our prediction that men would report higher intentions and sense of common cause under male leaders promoting common cause messages was not supported (H2).Despite this, our prediction that common cause framing would also result in higher collective action intentions and sense of common cause on behalf of both men and women was not wholly supported (H1a). Instead, providing partial support for Hypothesis 1a, women (but not men) expressed increased collective action intentions (but not sense of common cause) under common cause messages compared to meritocratic messages (Experiment 2). Meanwhile, men appear less affected by how they framed their message, or how positively or negatively they were evaluated as leaders (Experiment 2). Due to male feminists being free from the stigma associated with being a female feminist, this may have contributed to their higher mobilization of participants  signals that leader gender remains a crucial aspect of the leader-influence process when striving to mobilize follower support toward social change. It is not sufficient to merely “walk the talk” , p. 101 icipants . Additioicipants . Furthericipants .Taken together, our mobilization results speak to there being different mobilization pathways for men and women, just as there exists “differing starting places and processes for women and men” , p. 36 iand women that “we are all in this together”  with women  issue. However, these lowered scores could also indicate disagreement that the article discussed inequality as being a women’s only issue, and thus weakness of our vignette. Certainly, our manipulation differed slightly from Australian-based Gender Equality Commission, our vignette focused on a supposedly global context and authority figure, with absence of a relevant superordinate identity to provide a localized context or initial shared identity for participants to relate to . Given the central role that social identity has been shown to play in the current and extant work  are inexorably more invested in, and thus more readily mobilized toward gender equality, they still remain particularly sensitive to how calls for equality are framed. This is in comparison to men, who appear relatively unaffected by differing frames of gender equality. Ultimately, the current studies point to the importance of there being an intersection between leadership and solidarity processes in order to bridge the gap between women’s and men’s mobilization toward gender equality. This intersection requires further unpacking to achieve a more nuanced understanding. Importantly, just as the present research highlights the existence of different mobilization pathways for targets and non-targets of workplace gender inequality, so too might there exist different pathways for male and female equality initiative leaders to achieve successful mobilization of followers.Paradoxically, by virtue of their gender and the privileges it permits, male leaders seem to possess the ability to undertake gender equality leadership roles and mobilize men and women more effectively than female leaders . Indeed,SH assisted with the design, recruitment, analysis, and interpretation of Experiments 1 and 2, and additionally drafted the manuscript. ES was the primary supervisor of SH, assisted with the design, analysis, and interpretation of Experiments 1 and 2, and additionally provided theoretical and practical feedback on several drafts of the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Hallucination and dissociation have been found to be associated with imaginary friend play in childhood (CIC). Past studies have not investigated how this play relates to adult prodromal symptoms or how childhood adversity mediates the relationship. CIC play was examined in 278 participants, 18–24 years. CIC status predicted prodromal symptoms of hallucination only, whereas childhood adversity predicted all other symptoms. Mediation analysis found CIC's relation to hallucination symptoms was partially mediated by childhood adversity. Findings fit with views that CIC are a positive childhood experience which may convert to a negative developmental trajectory through the impact of childhood adversity. ChildreThere have been studies finding adult that dissociative experiences relate to CIC play , but no 2Data were gathered as part of an online survey conducted at a UK Higher Education Institution examining the social and emotional wellbeing of university students (SoWise).M = 20.38, SD = 1.56). Sociodemographic data included age, gender, and parental socioeconomic status. Some participants did not complete all sections; missingness was treated by deletion.This study reports on a subset of the measures from the SoWise survey using a purposive sub-sample of participants for analysis. Participants over the age of 24 were excluded for two reasons: 1) prodromal symptoms are known to occur from the onset of puberty to the early 20s  and 2) rAn imaginary friend can be classified as completely invisible, OR a doll or toy that you had given a personality to and played with for over 3 months. Participants were asked if they remembered having a CIC and if so what characteristics they exhibited . All participants reporting a CIC completed the qualitative questions about their companion. Qualitative questions were used to determine whether CICs were invisible or personified. If participants left the initial CIC question blank they were not considered in the analyses.CIC engagement was determined by the Imaginary Companion Questionnaire , defininThe screening measure for prodromal symptoms of psychosis was the Prodromal Questionaire-16 (PQ-16) . This seFinally, the Childhood Experience of Care and Abuse Questionnaire (CECA-Q)  was used3t (222) = −0.88, p = .381, but females X2 (N = 224) = 4.96, p = .026 reported significantly more CIC play.Of the 278 students, 224 reported on CIC status. 62 (22%) reported CIC play, with one removed because the CIC was described as a result of psychosis. There were no age effects, M = 4.53, SD = 3.59). No gender, t (216) = −0.54, p = .590, or age, r = 0.07, p = .331, differences were found.The PQ-16 was completed by 218  participants, reporting a range of 0–15 symptoms (X2 (N = 225) = 1.64, p = .201, or age, t (223) = −0.72, p = .475, differences were found for this variable.The CECA-Q was completed by 225  participants. No gender, The relationship between CIC status, prodromal symptoms, and adverse childhood experiences was measured using three Poisson regressions with 1) hallucinations/perceptual abnormality, 2) unusual thought content/delusional ideas/paranoia, and 3) negative prodromal symptoms reported as the outcome variables. CIC status and high/low adversity in childhood were entered as predictor variables. Gender and socioeconomic status were covariates. An interaction term was also entered.p = .002. Those reporting low adversity in the hallucination model also reported 58% less prodromal symptoms than those with high adversity scores, Exp (B) 0.423 ; this was also significant, p < .001. Furthermore there was a significant interaction, Exp (B) 1.935 ; p = .013. Those reporting both CIC and high adversity reported 94% more prodromal symptoms.Those reporting no CIC (NIC) in childhood in the hallucination model reported 53% less prodromal hallucination symptoms in comparison to the CIC group, Exp (B) 0.473 ; this was a significant predictor, p = .003, as well as the natural direct effect  p = .032, and the natural indirect effect  p = .007.A mediation analysis was run using Stata-15 and the PARAMED module using the bootstrap method to estimate bias-corrected confidence intervals. The relationship between CIC status and hallucination symptoms was mediated by childhood adversity where the total effect was significant  p = .088. Those reporting low adversity scores reported 40% less prodromal symptoms than those reporting high adversity, Exp (B) 0.601 ; this was significant, p = .017. No significant interaction was found, p = .338.There were no main effects of CIC status in the model predicting unusual thought content symptoms, p = .306; however those reporting low adversity reported 47% less prodromal symptoms than those with high adversity in childhood, Exp (B) 0.527 , p = .018. There was no interaction, p = .333.In the third regression looking at negative symptoms, there was no significant contribution of CIC status, X2 (N = 224) = 8.32, p = .004. See Adults with a CIC were more likely to report high adversity, 4Reporting concurrent prodromal symptoms of hallucination/perceptual abnormality was associated with self-report of CICs. CIC status did not predict report of unusual thought content or negative symptoms. Childhood adversity, however, related to all three types of prodromal symptoms and partially mediated the relationship between CICs and hallucination/perceptual symptoms.These findings are in line with previous research suggesting that having a CIC should be considered a form of non-pathological hallucination-like-experience  that maySeveral interpretations of the results are possible. Firstly, children's experiences with typical hallucination-like experiences in the form of interacting with a CIC may become prone to experience non-clinical prodromal symptoms of hallucination with the addition of life stressors. Secondly, children with CICs may become accustomed to speaking about imaginary invisible beings or voices throughout their development, and would be more likely to report these experiences than their peers.Limitations of the survey design were mitigated through the use of reliable and valid measures appropriate to the population. It would be useful to incorporate longitudinal design to find out more about the prodromal symptom trajectory of CIC individuals from childhood to adulthood. The regressions did show dispersion in the sample as well as having an unequal sample size; however these parametric tests have been shown to be robust against violations of assumptions .In summary, this research is consistent with the developmental perspective of the continuum of hallucination from pathological to non-pathological, and supports the notion that CICs may be a form of hallucination-like-experience which, particularly when combined with adversity, may influence the trajectory of non-clinical prodromal hallucination report.The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. All procedures involving human subjects were approved by the university ethics review board.Written consent was obtained from all subjects.Dr. Davis: None, has nothing to disclose, Dr. Webster: None, has nothing to disclose, Dr. Fernyhough: None, has nothing to disclose, Dr. Ralston: None, has nothing to disclose, Dr. Kola-Palmer: None, has nothing to disclose, Professor. Stain: None, has nothing to disclose.