186 research outputs found
Cultivation of Artificial Algal Crust and Its Effect on Soil Improvement in Sandy Area
Algae are the pioneer species of biological soil crusts. Cyanobacteria, microschwannophyta and pseudocladophyta can form fixed quicksand algae crusts on the surface of sand surface. Through artificial culture, soil crusts can be formed in a short time. The development and succession of algeal-sand crust promoted the enrichment of nutrients in the sand surface layer, and created conditions for the reproduction of micro-soil organisms and the colonization of herbaceous plants, thus promoting the desert ecosystem to enter a virtuous cycle. This chapter will focus on the cultivation process of artificial soil crust and its effect on soil improvement (soil organic matter and nitrogen) in sandy areas. In conclusion, the application of algal solution can rapidly form algal crusts, and according to the research results, the formation of algal crusts can significantly improve the chemical and biological properties of soil
The effects of litter input and increased precipitation on soil microbial communities in a temperate grassland
Global warming has contributed to shifts in precipitation patterns and increased plant productivity, resulting in a significant increase in litter input into the soils. The enhanced litter input, combined with higher levels of precipitation, may potentially affect soil microbial communities. This study aims to investigate the effects of litter input and increased precipitation on soil microbial biomass, community structure, and diversity in a temperate meadow steppe in northeastern China. Different levels of litter input (0%, +30%, +60%) and increased precipitation (0%, +15%, +30%) were applied over a three-year period (2015–2017). The results showed that litter input significantly increased the biomass of bacteria and fungi without altering their diversity, as well as the ratio of bacterial to fungal biomass. Increased precipitation did not have a notable effect on the biomass and diversity of bacteria and fungi, but it did increase the fungal-to-bacterial biomass ratio. However, when litter input and increased precipitation interacted, bacterial diversity significantly increased while the fungal-to-bacterial biomass ratio remained unchanged. These findings indicate that the projected increases in litter and precipitation would have a substantial impact on soil microbial communities. In energy-and water-limited temperate grasslands, the additional litter inputs and increased precipitation contribute to enhanced nutrient and water availability, which in turn promotes microbial growth and leads to shifts in community structure and diversity
ISSN 2347-9523 (Print)
Abstract: When interpreting the thought of new urbanization, the paper describes the significance of social and cultural ecology planning ideas on new urbanization. Furthermore, the problems existed in the process of urbanization in China are analyzed. The problems mainly embodied in three aspects: the loss of culture in social and cultural ecology; lack of inheritance, development, integration and enhancement to cultural resources and regional context; and the construction of urban and rural is disordered. Based on these, four aspects of planning strategies are proposed: construct ecological culture; build a harmonious and cultural environment; develop, protect and expand cultural resources; and strengthen urban characteristics
Anatomical and Physiological Plasticity in Leymus chinensis (Poaceae) along Large-Scale Longitudinal Gradient in Northeast China
Although it has been widely accepted that global changes will pose the most important constrains to plant survival and distribution, our knowledge of the adaptive mechanism for plant with large-scale environmental changes (e.g. drought and high temperature) remains limited.An experiment was conducted to examine anatomical and physiological plasticity in Leymus chinensis along a large-scale geographical gradient from 115° to 124°E in northeast China. Ten sites selected for plant sampling at the gradient have approximately theoretical radiation, but differ in precipitation and elevation. The significantly increasing in leaf thickness, leaf mass per area, vessel and vascular diameters, and decreasing in stoma density and stoma index exhibited more obvious xerophil-liked traits for the species from the moist meadow grassland sites in contrast to that from the dry steppe and desert sites. Significant increase in proline and soluble sugar accumulation, K(+)/Na(+) for the species with the increasing of stresses along the gradient showed that osmotic adjustment was enhanced.Obvious xerophytic anatomical traits and stronger osmotic adjustment in stress conditions suggested that the plants have much more anatomical and physiological flexibilities than those in non-stress habitats along the large-scale gradient
Barriers to identifying eating disorders in pregnancy and in the postnatal period: a qualitative approach.
BACKGROUND: Eating Disorders (ED) are mental health disorders that typically effect women of childbearing age and are associated with adverse maternal and infant outcomes. UK healthcare guidance recommends routine enquiry for current and past mental illness in antenatal and postnatal care for all women, and that pregnant women with a known ED are offered enhanced monitoring and support. Midwives and health visitors are ideally placed to identify and support women with ED as they are often the primary point of contact during the antenatal and postnatal periods. However, research on the barriers to identifying ED in the perinatal period is limited. This study aimed to understand the barriers to disclosure and identification of ED in pregnancy and postnatally as perceived by women with past or current ED, and midwives and health visitors working in the UK National Health Service. METHODS: Two studies were undertaken: mixed-measures survey of pregnant and postnatal women with current or past ED; focus groups with student and qualified midwives and health visitors. RESULTS: Five themes emerged on the barriers to disclosure in pregnancy as perceived by women: stigma, lack of opportunity, preference for self-management, current ED symptomatology and illness awareness. Four themes were identified on the barriers to identification of ED in pregnancy and in the postnatal period as perceived by health professionals: system constraints, recognition of role, personal attitudes, and stigma and taboo. CONCLUSIONS: Several barriers to the identification of ED during and after pregnancy were described, the main factors were stigma and poor professional training. Perinatal mental health is becoming increasingly prioritised within national policy initiatives; however, ED continue to be neglected and increased awareness is needed. Similarly, clinical guidance aimed at responding to the rising prevalence of obesity focus on changing nutrition but not on assessing for the presence of ED behaviours that might be affecting nutrition. Improving education and training for health professionals may contribute to reducing stigma and increase confidence in identifying ED. The barriers identified in this research need to be addressed if recognition and response to women with ED during the perinatal period is to improve
Molecular Ecology of Pyrethroid Knockdown Resistance in Culex pipiens pallens Mosquitoes
Pyrethroid insecticides have been extensively used in China and worldwide for public health pest control. Accurate resistance monitoring is essential to guide the rational use of insecticides and resistance management. Here we examined the nucleotide diversity of the para-sodium channel gene, which confers knockdown resistance (kdr) in Culex pipiens pallens mosquitoes in China. The sequence analysis of the para-sodium channel gene identified L1014F and L1014S mutations. We developed and validated allele-specific PCR and the real-time TaqMan methods for resistance diagnosis. The real-time TaqMan method is more superior to the allele-specific PCR method as evidenced by higher amplification rate and better sensitivity and specificity. Significant positive correlation between kdr allele frequency and bioassay-based resistance phenotype demonstrates that the frequency of L1014F and L1014S mutations in the kdr gene can be used as a molecular marker for deltamethrin resistance monitoring in natural Cx. pipiens pallens populations in the East China region. The laboratory selection experiment found that L1014F mutation frequency, but not L1014S mutation, responded to deltamethrin selection, suggesting that the L1014F mutation is the key mutation conferring resistance to deltamethrin. High L1014F mutation frequency detected in six populations of Cx. pipens pallens suggests high prevalence of pyrethroid resistance in Eastern China, calling for further surveys to map the resistance in China and for investigating alternative mosquito control strategies
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Splitting Frames Based on Hypothesis Testing for Patient Motion Compensation in SPECT
Patient motion is a significant cause of artifacts in SPECT imaging. It is important to be able to detect when a patient undergoing SPECT imaging is stationary, and when significant motion has occurred, in order to selectively apply motion compensation. In our system, optical cameras observe reflective markers on the patient. Subsequent image processing determines the marker positions relative to the SPECT system, calculating patient motion. We use this information to decide how to aggregate detected gamma rays (events) into projection images (frames) for tomographic reconstruction.
For the most part, patients are stationary, and all events acquired at a single detector angle are treated as a single frame. When a patient moves, it becomes necessary to split a frame into subframes during each of which the patient is stationary. This thesis presents a method for splitting frames based on hypothesis testing. Two competing hypotheses and probability model are designed. Whether to split frames is based on a Bayesian recursive estimation of the likelihood function. The estimation procedure lends itself to an efficient iterative implementation. We show that the frame splitting algorithm performance is good for a sample SNR. Different motion simulation cases are presented to verify the algorithm performance. This work is expected to improve the accuracy of motion compensation in clinical diagnoses
Climate-driven C-4 plant distributions in China: divergence in C-4 taxa
There have been debates on the driving factors of C-4 plant expansion, such as PCO2 decline in the late Micocene and warmer climate and precipitation at large-scale modern ecosystems. These disputes are mainly due to the lack of direct evidence and extensive data analysis. Here we use mass flora data to explore the driving factors of C-4 distribution and divergent patterns for different C-4 taxa at continental scale in China. The results display that it is mean annual climate variables driving C-4 distribution at present-day vegetation. Mean annual temperature is the critical restriction of total C-4 plants and the precipitation gradients seem to have much less impact. Grass and sedge C-4 plants are largely restricted to mean annual temperature and precipitation respectively, while Chenopod C-4 plants are strongly restricted by aridity in China. Separate regression analysis can succeed to detect divergences of climate distribution patterns of C-4 taxa at global scale
Fast Sampling Control of Singularly Perturbed Systems with Actuator Saturation and L
We will consider the problem of fast sampling control for singularly perturbed systems subject to actuator saturation and L2 disturbance. A sufficient condition for the existence of a state feedback controller is proposed. Under this controller, the boundedness of the trajectories in the presence of L2 disturbances is guaranteed for any singular perturbation parameter less than or equal to a predefined upper bound. To improve the capacity of disturbance tolerance and disturbance rejection, two convex optimization problems are formulated. Finally, a numerical example is presented to demonstrate the effectiveness of the main results of this paper
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