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Purpose: Based on a theoretical framework of ambidexterity in technology sourcing beyond organizational and technological boundaries, this study aims to explore how start-ups balance technology sourcing in organizational ambidexterity (TSOA) to produce high venture performance. Design/methodology/approach: A questionnaire survey is distributed among start-ups in the science and technology park of a university in eastern China, producing a total of 45 valid responses. The fuzzy-set approach to qualitative comparative analysis is used in this study. Findings: The findings show that start-ups achieve high venture performance through external technology sourcing (external exploration and exploitation) in the initial stage. In the growth stage, start-ups adopt external and internal technology sourcing (internal exploration and exploitation) to produce high venture performance. The technology sourcing strategy in ambidextrous activity for start-ups is punctuated equilibrium and evolving from the external ambidexterity to internally and externally coordinate ambidexterity at entrepreneurial stages. Originality/value: This study creatively adopts configuration-based thinking to investigate how to balance TSOA for high venture performance, extending the literature on technology sourcing and contributing to the balance theory of exploration and exploitation. [ABSTRACT FROM AUTHOR]

Global warming has been reported to cause reductions in crop yields. However, it was suggested that warming temperature might benefit crop productivity in some cool areas at high latitude. In this study, we conducted a 17‐year field experiment (2002–2018) on spring wheat in Inner Mongolia. Temperature changes during each growth stage of spring wheat were investigated. Responses of spring wheat yield to temperature changes during the specific growing stages were evaluated. Average annual maximum temperature (Tmax) and minimum temperature (Tmin) significantly increased over the past 17 years. However, Tmax did not show obvious increase trend during spring wheat growing seasons (p = 0.0672). Furthermore, Tmax also had no distinct change before or after anthesis. Tmin significantly increased during the whole growing season, as well as in pre‐ and post‐anthesis stages. Correlation analysis indicated that Tmax in the entire growing season and post‐anthesis did not affect spring wheat yield, but high Tmax during pre‐anthesis can improve grain yield. The Tmin during the life cycle and pre‐anthesis both had positive relationship with grain yield. Moreover, elevated temperature from seedling to stem elongation can benefit tiller formation and thus increasing spike number, which contributed to the significant yield increase (p = 0.0093). Overall, climate warming affect spring wheat yield in cool area, and increasing temperature that was below the optimum temperature can benefit wheat productivity. [ABSTRACT FROM AUTHOR]

Background: This study aimed to reveal the effects of the connectedness of primary health care (PHC) workers in social networks on their job burnout.Methods: Cross-sectional survey data of rural PHC workers in China were analyzed. A total of 663 respondents were enrolled. Chi-square and cumulative logistic regression were used to determine the effects of the connectedness of PHC workers in social networks on their job burnout.Results: PHC workers in rural China had high levels of emotional exhaustion (24.1%), depersonalization (15.7%), and lack of personal accomplishment (34.7%). More than half of the participants were in the middle connectedness level in terms of their advisory (70.4%) and friendship (70.3%) networks. The degree of emotional exhaustion seemed to increase when participants had a low connectedness in their friendship networks (β = 0.769, 95% CI = 0.080-1.458, P = 0.029). Respondents with the middle level of connectedness in advisory networks had higher levels of depersonalization (β = 0.739, 95% CI = 0.130-1.348, P = 0.017) and lack of personal accomplishment (β = 0.583, 95% CI = 0.111-1.055, P = 0.015) than those with the high degree of connectedness in advisory networks.Conclusions: The connectedness of PHC workers in social networks influenced their job burnout. Thus, organizations should establish an informal communication platform and information feedback mechanism, promote and manage friendship networks, and help PHC workers overcome emotional exhaustion. Managers should also encourage individuals with a high level of connectedness in advisory networks play the role of "opinion leader" so that they can help others mitigate burnout. [ABSTRACT FROM AUTHOR]

Uncertainty in the food supply continues to increase due to COVID-19 and geopolitical conflicts, and reducing farmland abandonment is an important measure for ensuring food security. In recent years, the Chinese government has promoted e-commerce demonstration projects in rural areas, so we ask does the spread of e-commerce reduce farmland abandonment? This study first constructs a theoretical framework for the effect of e-commerce on farmland abandonment and then quantifies that effect through spatial analysis and econometric models based on 12,732 households in the China Rural Household Panel Survey (CRHPS). The study found that there was a significant spatial aggregation between the popularization of e-commerce and the distribution of abandoned farmland, with a significant negative correlation between these two factors. The popularization of e-commerce has reduced farmland abandonment. The probability and size of farmland abandonment by farmers dropped by 4.1 % and 17.5 % when e-commerce was promoted in a village; the probability and size of farmland abandonment by farmers dropped by 7.8 % and 38.7 % when the rate of the popularization for e-commerce in villages increased by 1 %, respectively. E-commerce can reduce farmland abandonment in rural areas by absorbing returning labour, stimulating the land transfer market and revitalizing rural industry. With the improvement of physical infrastructure such as rural roads, the government should pay attention to the construction of digital villages including e-commerce infrastructure and continue to innovate new ways small farmers to participate in e-commerce, thus helping transform rural spaces and reusing idle land resources. • There is a significant negative relationship between e-commerce and farmland abandonment. • The popularization of e-commerce has reduced farmland abandonment. • E-commerce can reconfigure factors of production by absorbing labour, stimulating land transfer and revitalizing industry. • Digital village construction deserves to be given attention to revitalize the unused land resources. [ABSTRACT FROM AUTHOR]

The sustained growth of non-farm wages has led to large-scale migration of rural population to cities in China, especially in mountainous areas. It is of great significance to study the spatial and temporal pattern of population migration mentioned above for guiding population spatial optimization and the effective supply of public services in the mountainous areas. Here, we determined the spatiotemporal evolution of population in the Chongqing municipality of China from 2000–2018 by employing multi-period spatial distribution data, including nighttime light (NTL) data from the Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) and the Suomi National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP-VIIRS). There was a power function relationship between the two datasets at the pixel scale, with a mean relative error of NTL integration of 8.19%, 4.78% less than achieved by a previous study at the provincial scale. The spatial simulations of population distribution achieved a mean relative error of 26.98%, improved the simulation accuracy for mountainous population by nearly 20% and confirmed the feasibility of this method in Chongqing. During the study period, the spatial distribution of Chongqing's population has increased in the west and decreased in the east, while also increased in low-altitude areas and decreased in medium-high altitude areas. Population agglomeration was common in all of districts and counties and the population density of central urban areas and its surrounding areas significantly increased, while that of non-urban areas such as northeast Chongqing significantly decreased. [ABSTRACT FROM AUTHOR]

Effectively evaluating the effects of urban forms on CO 2 emissions has become a hot topic in socioeconomic sustainable development; however, few studies have been able to explore the urban form-CO 2 emission relationships from a multi-perspective view. Here, we attempted to analyze the relationships between urban forms and CO 2 emissions in 264 Chinese cities, with explicit consideration of the government policies, urban area size, population size, and economic structure. First, urban forms were calculated using the urban land derived from multiple-source remote sensing data. Second, we collected and processed CO 2 emissions and three control variables. Finally, a correlation analysis was implemented to explore whether and to what extent the spatial patterns of urban forms were associated with CO 2 emissions. The results show that urban form irregularity had a more significant impact on CO 2 emissions in low-carbon pilot cities than in non-pilot cities. The impact of the complexity of urban forms on CO 2 emissions was relatively significant in the small- and large-sized cities than in the medium-sized cities. Moreover, urban form complexity had a significant correlation with CO 2 emissions in all of the cities, the level of which basically increased with the population size. This study provides scientific bases for use in policy-making to prepare effective policies for developing a low-carbon economy with consideration of the associations between urban forms and CO 2 emissions in different scenarios. • Urban form connectivity could help to reduce CO 2 emissions at the national scale. • Urban form connectivity had the most significant impact on CO 2 emissions in large-sized cities. • Urban form complexity had a significant impact on CO 2 emissions in the low-carbon pilot cities. • Only urban form irregularity had a positive impact on CO 2 emissions in the service cities. • There was a significant difference in the urban form-CO 2 emission relationships among cities of various population sizes. [ABSTRACT FROM AUTHOR]

The rapid urbanization of China related to fine particulate (PM 2.5) emissions has attracted global attention, and exploring how urban forms affect PM 2.5 concentration has become a hot topic for sustainable development of cites. Here, we combined multisource data and econometric models to quantify the relationships between urban forms and PM 2.5 concentration in 250 Chinese cities, with explicit consideration of urban area size, population size, economic structure, and geographical location. The results showed that urban expansion had significant positive impacts on PM 2.5 concentration in medium-sized (50–150 km2) and very large-sized cities (>250 km2). Urban form compactness tended to be beneficial for the reduction in PM 2.5 concentration in large cities (5 million < population < 10 million). The urban form-PM 2.5 concentration relationships were also dominated by economic structure change. That is, urban form irregularity/compactness played an important role in PM 2.5 concentration within second cities (the proportion of second industry > 50%) and other cities compared to third cities (the proportion of third industry > 50%). Moreover, a compact and connected urban form was found to be more beneficial for reducing PM 2.5 emissions in the northern region than in other regions. This study illustrates that the urban form-PM 2.5 concentration relationships are sensitive to the differences in urban types and suggests that flexible urban planning strategies can actually help to reduce PM 2.5 concentration in Chinese cities. [ABSTRACT FROM AUTHOR]

Land urbanization (LU) and population urbanization (PU) maintain the nature of spatiotemporal heterogeneity in China. As a municipality directly administered by the central government in the mode of "large cities and large rural areas", Chongqing's urbanization process is the epitome of China's urbanization process. This paper examines the spatiotemporal variability of LU and PU in Chongqing on the basis of nighttime light data, the elasticity coefficient of the coupling relationship, and GWR. The results show that (1) the urban land and urban population in Chongqing grew notably from 2008 to 2018, with average annual growth rates of 9.4% and 2.3%, respectively. (2) The coupling coordination coefficient of LU and PU in Chongqing was 0.24, and the total number of districts and counties with uncoordinated development increased, but the overall uncoordinated situation gradually improved over the period. (3) The influence of PU on LU in each district and county increased year by year, and it showed a decreasing trend from southwest to northeast in Chongqing, which indicates that LU was increasingly adapted to the construction needs of PU. The gap between LU and PU widened due to the household registration system, land fiscal policies and other policies. After the reform of the household registration system and the adjustment of new pilot policies targeting the construction of new-type urbanization, the coupling relationship between LU and PU was gradually improving to the coordinated mode. The findings indicate that Chinese urban areas should adhere to the principle of new-type urbanization construction and carry out scientific land planning strategies, strictly controlling land expansion to promote the reasonable development of population growth.

Objectives: This study investigated the usefulness and performance of a two-stage attention-aware convolutional neural network (CNN) for the automated diagnosis of otitis media from tympanic membrane (TM) images., Design: A classification model development and validation study in ears with otitis media based on otoscopic TM images. Two commonly used CNNs were trained and evaluated on the dataset. On the basis of a Class Activation Map (CAM), a two-stage classification pipeline was developed to improve accuracy and reliability, and simulate an expert reading the TM images., Setting and Participants: This is a retrospective study using otoendoscopic images obtained from the Department of Otorhinolaryngology in China. A dataset was generated with 6066 otoscopic images from 2022 participants comprising four kinds of TM images, that is, normal eardrum, otitis media with effusion (OME) and two stages of chronic suppurative otitis media (CSOM)., Results: The proposed method achieved an overall accuracy of 93.4% using ResNet50 as the backbone network in a threefold cross-validation. The F1 Score of classification for normal images was 94.3%, and 96.8% for OME. There was a small difference between the active and inactive status of CSOM, achieving 91.7% and 82.4% F1 scores, respectively. The results demonstrate a classification performance equivalent to the diagnosis level of an associate professor in otolaryngology., Conclusions: CNNs provide a useful and effective tool for the automated classification of TM images. In addition, having a weakly supervised method such as CAM can help the network focus on discriminative parts of the image and improve performance with a relatively small database. This two-stage method is beneficial to improve the accuracy of diagnosis of otitis media for junior otolaryngologists and physicians in other disciplines., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Recent studies have demonstrated the limitations of the CHA2DS2-VASc score [congestive heart failure, hypertension, age (>65 years =1 point; >75 years =2 points), diabetes, and previous stroke/ transient ischemic attack (2 points), vascular disease] which lacks many of less common risk factors for stroke. Moreover, only two risk factors, gender and age, are assigned with different points according to the stratification in the CHA2DS2-VASc score. Thus, this meta-analysis was aimed to optimize the stratification of risk factors in and beyond the CHA2DS2-VASc score for patients in mainland China. PubMed, Embase, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), and Chinese Science and Technology Journal Database (VIP) were searched from their inception to January 2020 for articles assessing risk factors of nonvalvular atrial fibrillation (NVAF) with ischemic stroke in mainland China. Odd risks (ORs) with 95% confidence intervals (CIs) were applied for dichotomous variable, and the weighed mean differences (WMDs) with standard deviations (SDs) were used for continuous variables. The meta-analysis included 20 eligible studies involving 14,675 patients. Compared with the non-stroke group [systolic blood pressure (SBP): 132.99 mmHg, 95% CI: 131.86-134.12; diastolic blood pressure (DBP): 80.08 mmHg, 95% CI: 78.63-81.53], the ischemic stroke group (SBP:144.07 mmHg, 95% CI: 140.74- 147.40; DBP: 84.41 mmHg, 95% CI: 82.39-86.43) showed increased levels of SBP (WMD 10.98 mmHg, 95% CI: 7.80-14.17, P<0.00001) and DBP (WMD 4.46 mmHg, 95% CI: 2.57-6.35, P<0.00001). In addition, the ischemic stroke group demonstrated significantly lower levels of left ventricular ejection fractions (LVEFs) (WMD 3.05% 95% CI: -5.96 to -0.14, P=0.04), and significantly higher levels of total cholesterol (TC) (WMD 0.32 mmol/L, 95% CI: 0.04-0.61, P=0.02) and low density lipoprotein cholesterol (LDL-C) (WMD 0.14 mmol/L, 95% CI: 0.02-0.26, P=0.02), as compared with the non-stroke group. The optimized stratification and the addition of risk factors in and beyond the CHA2DS2-VASc score may improve the predictive performance, thus helping to differentiate patients with the real thromboembolic risk.

Exploring the coupling relationship between urban land and carbon emissions (CE) is one of the important premises for coordinating the urban development and the ecological environment. Due to the influence of the scale effect, a systematic evaluation of the CE at different scales will help to develop more reasonable strategies for low-carbon urban planning. However, corresponding studies are still lacking. Hence, two administrative scales (e.g., region and county) in Chongqing were selected as experimental objects to compare and analyze the CE at different scales using the spatiotemporal coupling and coupling coordination models. The results show that urban land and carbon emissions presented a significant growth trend in Chongqing at different scales from 2000 to 2015. The strength of the spatiotemporal coupling relationship between urban land and total carbon emissions gradually increased with increasing scale. At the regional scale, the high coupling coordination between urban land and total carbon emissions was mainly concentrated in the urban functional development region. Additionally, the high coupling coordination between urban land and carbon emission intensity (OI) was still located in the counties within the metropolitan region of Chongqing, but the low OI was mainly distributed in the counties in the northeastern and southeastern regions of Chongqing at the county level. This study illustrates the multiscale trend of CE and suggests differentiated urban land and carbon emission reduction policies for controlling urban land sprawl and reducing carbon emissions.

Whether the abnormal circadian rhythm of urinary sodium excretion is associated with hypertension in chronic kidney disease (CKD) is poorly understood. In this study, we assessed the relationship between the circadian rhythm of urinary sodium excretion and hypertension. Urinary samples were collected during both the day (07:00 to 22:00) and night (22:00 to 07:00) to estimate night/day urinary sodium excretion ratios. Blood pressure (BP) and clinical data were also measured. A total of 1,099 Chinese CKD patients were recruited, 308 patients were excluded, and 791 patients were final enrolled in this study. Among them, 291 patients were normotensive and 500 were hypertensive CKD patients. A 1:1 propensity score matching (PSM) analysis was performed with age and estimated glomerular filtration rate (eGFR) matched between 190 normotensive and hypertensive patients. In the full cohort and PSM cohort, multivariate regression analysis showed that the night/day urinary sodium excretion ratio was an independent risk factor for clinical hypertension, whereas 24 h urinary sodium excretion, diurnal and nocturnal urinary sodium excretion were not. When the night/day urinary sodium excretion ratios were further divided into tertiles (tertile 1 < 0.47, tertile 2, 0.47-0.84 and tertile 3 > 0.84), multivariate analysis showed that tertile 3 was independently associated with hypertension in the full and PSM cohorts. In addition, tertile 3 was also independently associated with eGFR ≤ 60 mL/min/1.73 m 2 and left ventricular hypertrophy. These data suggested that an abnormal circadian rhythm of urinary sodium excretion was independently associated with hypertension and target-organ damage. Individualized salt intake and therapeutic strategies should be used to normalize the natriuretic dipping profile in CKD patients., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Currently, whether the urban development in China satisfies Zipf's law across different scales is still unclear. Thus, this study attempted to explore whether China's urban development satisfies Zipf's law across different scales from the National Polar-Orbiting Partnership's Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) nighttime light data. First, the NPP-VIIRS data were corrected. Then, based on the Zipf law model, the corrected NPP-VIIRS data were used to evaluate China's urban development at multiple scales. The results showed that the corrected NPP-VIIRS data could effectively reflect the state of urban development in China. Additionally, the Zipf index ( q ) values, which could express the degree of urban development, decreased from 2012 to 2018 overall in all provinces, prefectures, and counties. Since the value of q was relatively close to 1 with an R 2 value > 0.70, the development of the provinces and prefectures was close to the ideal Zipf's law state. In all counties, q > 1 with an R 2 value > 0.70, which showed that the primate county had a relatively stronger monopoly capacity. When the value of q < 1 with a continuous declination in the top 2000 counties, the top 250 prefectures, and the top 20 provinces in equilibrium, there was little difference in the scale of development at the multiscale level with an R 2 > 0.90. The results enriched our understanding of urban development in terms of Zipf's law and had valuable implications for relevant decision-makers and stakeholders.

Due to remarkable socioeconomic development, an increasing number of karst rocky desertification areas have been severely affected by human activities in southern China. Effectively analyzing human activities in karst rocky desertification areas is a critical prerequisite for managing and restoring areas with tremendous negative impacts from desertification. At present, a timely and accurate way of quantifying the spatiotemporal variations of human activities in karst rocky desertification areas is still lacking. In this communication, we attempted to quantify human activities from the corrected Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) nighttime light composite data from 2012 to 2018 based on statistical analysis. The results show that a significant increase of night lights could be clearly identified during the study period. The total nighttime lights (TL) related to severe karst rocky desertification (S) were particularly concentrated in Guizhou and Yunnan. The nighttime light intensity (LI) related to the S areas in Chongqing was the strongest due to its rapid socioeconomic development. The annual growth rate of nighttime lights (GL) has been slow or even negative in Guangdong because of its various karst rocky desertification restoration programs. This communication could provide an effective approach for quantifying human activities and provide useful information about where prompt attention is required for policy-making on the restoration of the karst rocky desertification areas., Competing Interests: The authors declare no conflict of interest.