647 research outputs found

    Spinor field realizations of the non-critical W2,4W_{2,4} string based on the linear W1,2,4W_{1,2,4} algebra

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    In this paper, we investigate the spinor field realizations of the W2,4W_{2,4} algebra, making use of the fact that the W2,4W_{2,4} algebra can be linearized through the addition of a spin-1 current. And then the nilpotent BRST charges of the spinor non-critical W2,4W_{2,4} string were built with these realizations.Comment: 10 pages, no figures, revtex4 style, accepted by Commun.Theor.Phy

    Spinor Field Realizations of Non-critical W2,sW_{2,s} Strings

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    In this paper, we construct the nilpotent Becchi-Rouet-Stora-Tyutin(BRSTBRST) charges of spinor non-critical W2,sW_{2,s} strings. The cases of s=3,4s=3,4 are discussed in detail, and spinor realization for s=4s=4 is given explicitly. The BRSTBRST charges are graded.Comment: 9 pages, no figure

    A study of aerosol liquid water content based on hygroscopicity measurements at high relative humidity in the North China Plain

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    Water can be a major component of aerosol particles, also serving as a medium for aqueous-phase reactions. In this study, a novel method is presented to calculate the aerosol liquid water content at high relative humidity based on measurements of aerosol hygroscopic growth factor, particle number size distribution and relative humidity in the Haze in China (HaChi) summer field campaign (July–August 2009) in the North China Plain. The aerosol liquid water content calculated using this method agreed well with that calculated using a thermodynamic equilibrium model (ISORROPIA II) at high relative humidity (>60%) with a correlation coefficient of 0.96. At low relative humidity (<60%), an underestimation was found in the calculated aerosol liquid water content by the thermodynamic equilibrium model. This discrepancy mainly resulted from the ISORROPIA II model, which only considered limited aerosol chemical compositions. The mean and maximum values of aerosol liquid water content during the HaChi campaign reached 1.69 × 10−4 g m−3 and 9.71 × 10−4 g m−3, respectively. A distinct diurnal variation of the aerosol liquid water content was found, with lower values during daytime and higher ones at night. The aerosol liquid water content depended strongly on the relative humidity. The aerosol liquid water content in the accumulation mode dominated the total aerosol liquid water content

    Mapping QTLs for mineral accumulation and shoot dry biomass under different Zn nutritional conditions in Chinese cabbage ( Brassica rapa L. ssp. pekinensis )

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    Abstract Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the most important vegetables in China. Genetic dissection of leaf mineral accumulation and tolerance to Zn stress is important for the improvement of the nutritional quality of Chinese cabbage by breeding. A mapping population with 183 doubled haploid (DH) lines was used to study the genetics of mineral accumulation and the growth response to Zn. The genetic map was constructed based on 203 AFLPs, 58 SSRs, 22 SRAPs and four ESTPs. The concentration of 11 minerals was determined in leaves for 142 DH lines grown in an open field. In addition shoot dry biomass (SDB) under normal, deficient and excessive Zn nutritional conditions were investigated in hydroponics experiments. Ten QTLs, each explaining 11.1¿17.1% of the Na, Mg, P, Al, Fe, Mn, Zn and Sr concentration variance, were identified by multiple-QTL model (MQM) mapping. One common QTL was found affecting SDB under normal, deficient and excessive Zn nutritional conditions. An additional QTL was detected for SDB under Zn excess stress only. These results offer insights into the genetic basis of leaf mineral accumulation and plant growth under Zn stress conditions in Chinese cabbag

    Characteristics of the grain-filling process and starch accumulation of high-yield common buckwheat ‘cv. Fengtian 1’ and tartary buckwheat ‘cv. Jingqiao 2’

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    High-yield common buckwheat ‘cv. Fengtian 1’ (FT1) and tartary buckwheat ‘cv. Jingqiao 2’ (JQ2) were selected to investigate the characteristics of the grain-filling process and starch accumulation of high-yield buckwheat. FT1 had an average yield that was 43.0% higher than that of the control ‘cv. Tongliaobendixiaoli’ (TLBDXL) in two growing seasons, while JQ2 had an average yield that was 27.3% higher than that of the control ‘cv. Chuanqiao 2’ (CQ2). The Richards equation was utilized to evaluate the grain-filling process of buckwheat. Both FT1 and JQ2 showed higher values of initial growth power and final grain weight and longer linear increase phase, compared with respective control. These values suggest that the higher initial increasing rate and the longer active growth period during grain filling play important roles to increase buckwheat yield. Similar patterns of starch, amylose and amylopectin accumulation were detected in common buckwheat, leading to similar concentration of each constituent at maturity in FT1 and TLBDXL. Tartary buckwheat showed an increasing accumulation pattern of amylose in developing seeds, which differed from that of starch and amylopectin. This pattern led to a significant difference of the concentrations of amylose and amylopectin at maturity between JQ2 and CQ2, the mechanisms of which remained unclear. Nevertheless, both FT1 and JQ2 showed increased starch, amylose, and amylopectin accumulation during the physiological maturity of grains. The results suggest that prolonging the active grain-filling period to increase carbohydrate partitioning from source to seed sink can be an effective strategy to improve buckwheat yield

    A Probabilistic Model for Describing Short Fatigue Crack Growth Behavior of LZ50 Steel

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    Fatigue damage process of metal components and structures with smooth surface belongs primarily to stage of short fatigue crack. To characterize the random growth behavior of short fatigue crack and to apply the crack growth rate model for engineering safety assessment, a probabilistic model is proposed with consideration of the test data scattering regularity. This probabilistic model is based on the multi-microstructural barriers model and can describe the deceleration behavior of growth rate during the whole short fatigue crack propagation process. To take the statistical characteristics of whole test data into account, the idea from the general maximum likelihood method which is widely used in parameters estimation of fatigue S-N curves and ε-N curves is inherited. While estimating the parameters of the probabilistic model, conventional correlation coefficient optimization method is extended for calculating the parameters of both the mean curve and the standard deviation curve. Analysis on the test data of LZ50 steel indicates the reasonability and availability of present model

    Short Fatigue Crack Growth at Different Maintenance Times for LZ50 Steel

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    Based on the average fatigue life of LZ50 axle steel specimens without surface rolling, five maintenance times were determined. Accordingly, five groups of specimens were turned and rolled at above maintenance times and were fatigued using a replica technique. The results show that the crack growth rate is much lower than that before rolling at a given dominant short crack size. The effective short crack density of all specimens decreases significantly after maintenance. However, with the postponement of surface maintenance, the highest effective short crack density for the five studied groups of specimens increases continuously, while the average fatigue life decreases gradually. A maintenance time effect function is presented to refine a short crack growth model described previously. The revifined model can include a significant effect of the maintenance time on short crack growth and predict its patterns at different maintenance times with exiting test results for LZ50 axle steel.На основании средней усталостной долговечности образцов осевой стали LZ50, не подвергавшихся поверхностной обкатке роликами, были определены пять модельных межремонтных циклов. Соответственно пять групп образцов были обточены и обкатаны роликами при вышеуказанных межремонтных циклах и подвергнуты испытанию на усталость по методу реплик. Результаты показывают, что скорость роста трещин гораздо ниже таковой до обкатки роликами при заданном преобладающем размере коротких трещин. Эффективная плотность коротких трещин для всех образцов значительно уменьшается после обработки. Однако если поверхностную обработку вовремя не выполняют, наибольшая эффективная плотность коротких трещин для пяти исследуемых групп образцов непрерывно возрастает, тогда как средняя усталостная долговечность постепенно снижается. Приведена функция, описывающая эффект межремонтных циклов, для уточнения предложенной ранее модели роста коротких трещин. Уточненная модель может учитывать существенное влияние межремонтного цикла на рост коротких трещин и прогнозировать характер их роста при различных межремонтных циклах на основании полученных результатов испытаний осевой стали LZ50

    Photosynthetic characteristics of summer maize under different planting patterns and the responses to nitrogen application of previous crop

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    Maize (Zea mays L.) is one of the most important grain crops in the North China Plain. Management practices affect the photosynthetic characteristics and the production of summer maize. This two-year (2014-2015) study examined the effects of different planting patterns and the application of nitrogen to previous winter wheat (Triticum aestivum L.) on the photosynthetic characteristics, yield and radiation use efficiency (RUE) of summer maize. Field experiments used a two-factor split-plot design with three replicates at Taian, Shandong Province, China (36°09′ N, 117°09′ E). The experiments involved two planting patterns (ridge planting, RP; and uniform row planting, UR) and two nitrogen application levels of previous winter wheat (N1, 112.50 kg ha-1; N2, 225.00 kg ha-1). The results indicated that the application of nitrogen on previous crop and ridge planting of the following crop had significant effects on the photosynthetic characteristics and yields of summer maize. Compared with UR, this study found that RP increased the chlorophyll content index (CCI), leaf area index (LAI), net photosynthetic rate (Pn), dry matter (DM), yield and grain RUE by 4.1%, 6.3%, 5.2%, 6.4%, 8.9% and 9.4%, respectively. The CCI, LAI, Pn, yield, and grain RUE of N2 were 9.7%, 3.3%, 3.7%, 10.0% and 10.1% higher than those of N1, respectively. RP combined with the application of nitrogen on previous crop of winter wheat could increase the CCI, LAI, Pn, DM, ultimately increasing the grain yield and RUE of the following summer’s maize. It was concluded that previous crop nitrogen application and RP pattern treatment resulted in optimal cropping conditions for the North China plain

    Does entropic force always imply the Newtonian force law?

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    We study the entropic force by introducing a bound SA3/4S \le A^{3/4} between entropy and area which was derived by imposing the non-gravitational collapse condition. In this case, applying a modified entropic force to this system does not lead to the Newtonian force law.Comment: 11 pages, version to appear in EPJ
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