Search

This work is focused on the topology optimization of structures that are subjected to harmonic force excitation with prescribed frequency and amplitude. As an important objective of such a design problem, the natural resonance frequency of the structure is driven far away from the prescribed excitation frequency for the purpose of avoiding resonance and reducing the vibration level. Therefore when the excitation frequency is higher than the natural resonance frequency of the structure, the natural resonance frequency will decrease, then the optimum topology configuration will be distorted with large amount of gray elements. A MAC (Modal Assurance Criteria) based excitation frequency increasing method is proposed to obtain a desired configuration. MAC is adopted here to track the natural resonance frequency which can provide the baseline reference for the current excitation frequency during the optimum iterative procedure. Then the excitation frequency increases progressively up to its originally prescribed value. By means of numerical examples, the proposed formulation can generate effective topology configurations which can avoid resonance.

Dense planting effectively increases maize yield while increasing stalk lodging risk. Appropriate row spacing can improve the maize population structure and stalk lodging resistance, but its physiological ecological mechanisms and interaction with planting density are unclear. Here, a two-year field experiment to determine the joint effects of row spacing and planting density on maize stem characteristics and the quantitative relationship of the light condition within a maize population with stalk lodging resistance indicated that the stalk mechanical strength showed a quadratic function relationship with photosynthetically active radiation (PAR), whereas the lodging rate showed an exponential function relationship with basal light transmittance (LT). Further, the basal LT was significantly positively correlated with basal internode thickness, dry weight per unit stem length (DWUL), mechanical and cortical tissue thickness, and lignin and cellulose contents. Increasing the planting density decreased the basal LT and PAR; correspondingly decreased the basal internode thickness, DWUL, mechanical and cortical tissue thickness, lignin and cellulose contents, and stalk mechanical strength; and increased the lodging rate, while increasing row spacing did the opposite. Thus, optimizing the row spacing enhanced the lodging resistance through LT and PAR improvement of the lower part of the population and further increased the grain yield by optimizing the yield components. The appropriate row spacing varied with the planting density. The proper strategy for high stalk lodging resistance and grain yielding under this experimental condition was 67,500 plants ha−1 density with 60 + 60 cm equal row spacing. [ABSTRACT FROM AUTHOR]

Although there are many new types of environmentally friendly fertilizers that can improve maize yield, chemical fertilizers are the most widespread type of fertilizer used in the agricultural sector of China due to their low cost and ease of application. However, the misuse of chemical fertilizers could lead to environmental problems, such as the massive emission of greenhouse gases (GHG). Therefore, it is important to determine how fertilizer-use efficiency (FUE) could be improved to stabilize or increase maize yield while reducing GHG emissions. In this study, we collected 6618 date records which include three datasets (for N, P, and K) from five maize-growing regions in China from 2005 to 2018, and performed a meta-analysis on the effects of N, K, and P fertilization levels on maize yield, partial factor productivity (PFP), agronomic efficiency (AE), and the carbon footprint of maize production. Additionally, scenario analyses were performed to estimate optimal fertilizer application rates for stabilizing or increasing maize yield while reducing GHG emissions. It was shown that FUE and maize yield responses to fertilization level varied in different regions. Compared to the past, the maize production of China has improved significantly in terms of FUE and its carbon footprint in recent years. Because of improvements in maize cultivars and cultivation technologies, it is possible to decrease N, P, and K application rates and reduce per unit area carbon footprint of maize, without compromising yield. In the future, N fertilization should be reduced by 10% from current levels, and the application of P and K fertilizers should be increased or decreased depending on the conditions of each maize-growing region. Thus, it should be possible to stabilize or even increase yields and reduce GHG emissions of maize production, thereby achieving green and efficient development. [ABSTRACT FROM AUTHOR]

Purpose: To explore changes of depression, anxiety and sleep disturbance in patients with episodic cluster headache inside and outside the attack period and assess the therapy to improve the treatment. Patients and Methods: We prospectively recruited 396 patients from 11 specialized headache outpatients and analyzed their headache characteristics, Hospital Anxiety Depression Scale scores, Pittsburgh sleep quality index scores, and the usage of psychiatric medications during as well as 1 month after the attack period. Results: A total of 220 patients completed the follow-up, 52.73% of whom had anxiety, 47.27% had depression and 49.09% had sleep disturbance inside the attack period. At follow-up, the percentage of these patients significantly decreased to 16.36%, 21.82% and 14.55% in the remission period, respectively (p < 0.05). Antidepressants and mood stabilizers were prescribed to 58.18% of the patients. However, both of the changes of Hospital Anxiety Depression Scale scores after the end of the attack period for anxiety (3.52± 2.91 vs 3.32± 3.09, p =0.61) and depression (3.41± 3.33 vs 2.90± 3.58, P =0.28) were comparable in patients with and without taking these medications. Nocturnal onset of headache was positively correlated with Pittsburgh score (OR=8.71), anxiety (OR=2.33) and depression scores (OR=3.56) (p < 0.05). Conclusion: Depression, anxiety and sleep disturbance were significantly alleviated after the attack period. However, psychiatric medications showed limited effect on depression and anxiety. Additionally, the nocturnal attack may cause anxiety and depression in episodic cluster headache. [ABSTRACT FROM AUTHOR]

Non-structural carbohydrates (NSCs) are an important energy source for plant growth and metabolism. Analysis of NSC changes can provide important clues to reveal the adaptation mechanisms of plants to a specific environment. Although considerable differences have been reported in NSCs in response to nitrogen (N) application among crop species and cultivars, previous studies have mostly focused on the differences in leaves and stems. However, the effects of N on the characteristics of accumulation and translocation of NSC in maize with different levels of N tolerance remain unclear. To determine differences in the N levels, two cultivars (N-efficient ZH311 and N-inefficient XY508) were grown in field pots (Experiment I) and as hydroponic cultures (Experiment II) and were supplemented with different concentrations of N fertilizer. In both experiments, low-N stress significantly increased the accumulation of NSCs in maize vegetative organs and increased the translocation rate of NSCs in the stems and their apparent contribution to yield, thereby reducing the yield loss caused by low-N stress. N application had a greater effect on starch content in the vegetative organs of ZH311, but had less effect on soluble sugar (SS) and NSC content in the whole plant and starch content in the ears. ZH311 could convert more starch into SS under low N conditions to adapt to low N environments than XY508, while ensuring that grain yield and starch quantity were not affected. This is evidently an important physiological mechanism involved in this cultivar's tolerance to low N conditions. [ABSTRACT FROM AUTHOR]

Intercropping is an important agronomic practice adopted to increase crop production and resource efficiency in areas with intensive agricultural production. Two sequential field trials were conducted in 2015–2016 to investigate the effect of shading on the morphological features, leaf structure, and photosynthetic characteristics of soybean in a maize-soybean relay-strip intercropping system. Three treatments were designed on the basis of different row configurations A1 (“50 cm + 50 cm” one row of maize and one row of soybean with a 50 cm spacing between the rows), A2 (“160 cm + 40 cm” two rows of maize by wide-narrow row planting, where two rows of soybean were planted in the wide rows with a width of 40 cm, and with 60 cm row spacing was used between the maize and soybean rows), and CK (sole cropping of soybean, with 70 cm rows spacing). Results showed that the photosynthetically active radiation transmittances of soybean canopy at V5 stage under A2 treatment (31.1%) were considerably higher than those under A1 (8.7%) treatment, and the red-to-far-red ratio was reduced significantly under A1 (0.7) and A2 (1.0) treatments compared with those under CK (1.2). By contrast with CK, stem diameter, total aboveground biomass, chlorophyll content and net photosynthetic rate decreased significantly except plant height under A1 and A2. The thickness of palisade tissue and spongy tissue of soybean leaf under A1 and A2 were significantly reduced at V5 stage compared with CK. The leaf thicknesses under A1 and A2 were lower than those in CK by 39.5% and 18.2%, respectively. At the R1 stage of soybean (after maize harvest), the soybean plant height, stem biomass, leaf biomass and petiole biomass under A1 and A2 treatments were still significantly lower than those under CK, but no significant differences were observed in Chl a/b, Pn, epidermis thickness and spongy tissue thickness of soybean leaves in A2 compared with CK. In addition, the soybean yields (g plant-1) under A1 and A2 were 54.69% and 16.83% lower than those in CK, respectively. These findings suggested that soybean plants can regulate its morphological characteristics and leaf anatomical structures under different light environments. [ABSTRACT FROM AUTHOR]

The intensity and quality (red to far-red (R/Fr) ratio) of light directly affect growth of plant under shading. Gibberellins (GAs) and auxin [indole-3-acetic acid (IAA)] play important roles in mediating the shading adaptive responses of plants. Thus, the intensity and quality of the uncoupling light from shading were assessed to identify the influence of each component on the morphology and matter distribution of the leaf, stem, and petiole. This assessment was based on the changes in endogenous Gibberellin 1 (GA1) and IAA levels. Soybean plants were grown in a growth chamber with four treatments [normal (N), N+Fr, low (L), and L+Fr light]. Results revealed that the reductions in photosynthetically active radiation (PAR) and R/Fr ratio equally increased height and stem mass fractions (SMFs) of the soybean seedling. The light intensity significantly influenced the dry mass per unit area and mass fraction of soybean leaves, whereas the light quality regulated the petiole elongation and mass fraction. Low R/Fr ratio (high Fr light) increased the soybean biomass by improving the photosynthetic assimilation rate and quantum yield of photosystem II. In addition, the IAA and GA1 levels in the leaf, stem, and petiole did not reflect the growth response trends of each tissue toward light intensity and quality; however, trends of the IAA-to-GA1 content ratios were similar to those of the growth and matter allocation of each soybean tissue under different light environments. Therefore, the response of growth and matter allocation of soybean to light intensity and quality may be regulated by the IAA-to-GA1 content ratio in the tissues of the soybean plant. [ABSTRACT FROM AUTHOR]

Photosynthesis is dependent on the density and quality of light that reaches chloroplasts. Shade conditions are characterized by changes in light density and quality. These changes, which are represented by the red to far-red (R/Fr) ratio of light, directly affect the photosynthetic capacity of soybean in close-planting and intercropping systems. We postulated that high far-red light under shade conditions would improve crop photosynthesis. Herein, we conducted a quantitative proteomic analysis through the isobaric tagging for relative and absolute quantification approach to investigate the response of photosynthetic proteins to the interaction between light intensity and quality. We identified 7834 proteins (P value < 0.05, FC > 1.3) from soybean leaves. Among these proteins, 98 are associated with differential chloroplast accumulation under shade (S, low light intensity and low R/Fr ratio) and normal light (N, normal light intensity and normal R/Fr ratio) conditions. Additionally, 134 are associated with differential chloroplast accumulation under low light (L, low light intensity and normal R/Fr ratio) and N conditions. Eight representative proteins that are involved in photosynthesis were differentially regulated under L and S treatments. These proteins included one protein involved in porphyrin and chlorophyll metabolism, three proteins involved in light-harvesting chlorophyll protein complex, and four proteins involved in photosynthesis. Among the eight differentially regulated proteins under L and S treatments, five up-regulated proteins (protochlorophyllide reductase; light-harvesting complex II chlorophyll a/b binding protein [Lhcb1]; Lhcb2; photosystem I subunit II; and plastocyanin [PetE]) and three down-regulated proteins (Lhcb4; Ferredoxin-1; and NADPH:quinone oxidoreductase [NQO]) were validated through quantitative reverse-transcription polymerase chain reaction and Western blot methods L and S treatments decreased net photosynthesis rate ( P n ) but increased chlorophyll content; thylakoid stacking; and photosystem II (PSII), PSI, and electron transport associated protein levels. Likewise, N and S treatments decreased PetE and NQO protein expression levels. This effect, in turn, decreased P700 oxidation. In addition, the higher far-red light of the S treatment than that of the L treatment increased P n by up-regulating the gene expressions of differential proteins. We conclude that light intensity directly affects photosynthesis by regulating the expression of photosynthetic proteins. High far-red light, however, can improve the photosynthetic capacity of plants under shade conditions. [ABSTRACT FROM AUTHOR]

Background: Migraine follow-up is difficult for outpatients, especially after the COVID-19 pandemic, we tried to identify the most appropriate telemedicine methods for migraine in terms of efficacy, safety, patient compliance, and patient and physician satisfaction., Methods: Migraine patients were screened from the Headache Center of the First Affiliated Hospital of Chongqing Medical University from September 2019 to December 2021 and randomly classified into an outpatient group and four telemedicine groups: social software, telephone, E-mail, and short message. Headache specialists followed up with the patients 3 and 6 months after their visit and asked about their satisfaction with the follow-up in each instance, as were the headache specialists., Results: A total of 147 migraine patients were included, of whom 65 completed the follow-up. After 3 and 6 months of follow-up, the proportion of patients whose monthly headache frequency decreased by over 50% in the social-software, telephone, and E-mail groups was no different from that in the outpatient group. A similar result was obtained from evaluations with the Visual Analog Scale, the Headache Impact Test and the Migraine Disability Assessment compared with baseline in social software and telephone groups. The compliance in social-software group was not worse than that in the outpatient group. The proportion of patients in the E-mail group who completed the follow-up and the proportion of patients in the telephone group who consistently took preventive medication were significantly lower than those in the outpatient group. After 6 months, the majority of patients in the outpatient, social-software, and telephone groups and headache specialists in the outpatient, social-software groups were satisfied with the follow-up, while fewer patients in the E-mail group and fewer specialists in the telephone and E-mail group showed their satisfaction., Conclusion: Compared with outpatient visits, it is safe and effective to use social software and telephone to follow up on migraine patients, and E-mail and short-message follow-up have lower feasibility. Migraine patients prefer social-software and telephone follow-up, while specialists prefer social-software follow-up., Competing Interests: 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., (Copyright © 2023 Liu, Liu, Yu, Zang and Tan.)