Active and passive critical slip fields for cohesionless soils and calculation of lateral earth pressures

A new method of solving earth pressure problems is proposed in this paper within the framework of the limit equilibrium approach. The concept of the critical slip field (CSF) is postulated: the active critical slip field (ACSF) in the active case, and the passive critical slip field (PCSF) in the passive case. Based on the principle of extremum thrust force (which is theoretically consistent with the principle of optimality) in conjunction with the method of slices, a numerical procedure is presented for the determination of such fields and consequently the distribution of earth pressures on retaining walls. For simplicity at this stage, the backfill material is assumed to be a homogeneous cohesionless soil with sloping ground surface carrying uniform and vertical surcharge, while the retaining wall is allowed to be battered, and the strength of the soil may be either fully or partially mobilised. Compared with the rigorous method (i.e. the method of characteristics), the proposed method is simple in principle and easily implemented in a computer program. However, it is more accurate than other approximate techniques and agrees well with available closed-form solutions. A number of examples of ACSF and PCSF are given in this paper, and the validity and efficiency of the proposed method are demonstrated. In addition, it is easy to extend this numerical procedure to obtain more general ACSF and PCSF accomodating non-homogeneous c, Ø soils subject to complicated loading conditions.published_or_final_versio

基于形态分割的高分辨率遥感影像道路提取

Author name used in this publication: 朱长青Author name used in this publication: 马秋禾Author name used in this publication: SHI Wen-zhong2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A new procedure for computing the factor of safety using the Morgenstern-Price method

By employing the same assumption regarding interslice forces as that used in the Morgenstern-Price method, two concise recurrence relations between interslice forces and interslice moments are derived which satisfy both force and moment equilibrium conditions. The Newton-Raphson method is used for determining the factor of safety and the associated scaling parameter of the interslice force function. Algebraic derivatives required in the solution process are evolved in a recursive manner which can be easily implemented in a computer program. The choices of initial values of safety factor and scaling parameter are suggested. The procedure proposed in this paper proves to be efficient and solutions converge rapidly.published_or_final_versio

DNA demethylases target promoter transposable elements to positively regulate stress responsive genes in Arabidopsis

© 2014 Le et al. Background: DNA demethylases regulate DNA methylation levels in eukaryotes. Arabidopsis encodes four DNA demethylases, DEMETER (DME), REPRESSOR OF SILENCING 1 (ROS1), DEMETER-LIKE 2 (DML2), and DML3. While DME is involved in maternal specific gene expression during seed development, the biological function of the remaining DNA demethylases remains unclear. Results: We show that ROS1, DML2, and DML3 play a role in fungal disease resistance in Arabidopsis. A triple DNA demethylase mutant, rdd (ros1 dml2 dml3), shows increased susceptibility to the fungal pathogen Fusarium oxysporum. We identify 348 genes differentially expressed in rdd relative to wild type, and a significant proportion of these genes are downregulated in rdd and have functions in stress response, suggesting that DNA demethylases maintain or positively regulate the expression of stress response genes required for F. oxysporum resistance. The rdd-downregulated stress response genes are enriched for short transposable element sequences in their promoters. Many of these transposable elements and their surrounding sequences show localized DNA methylation changes in rdd, and a general reduction in CHH methylation, suggesting that RNA-directed DNA methylation (RdDM), responsible for CHH methylation, may participate in DNA demethylase-mediated regulation of stress response genes. Many of the rdd-downregulated stress response genes are downregulated in the RdDM mutants nrpd1 and nrpe1, and the RdDM mutants nrpe1 and ago4 show enhanced susceptibility to F. oxysporum infection. Conclusions: Our results suggest that a primary function of DNA demethylases in plants is to regulate the expression of stress response genes by targeting promoter transposable element sequences

Use of moxibustion to treat primary dysmenorrhea at two interventional times: study protocol for a randomized controlled trial

published_or_final_versio

Genetic analysis of the naked trait in panicles of hexaploid oat

The aim of this study was to estimate the number of genes that control the naked (hull-less) trait and the mode of expression of this characteristic in panicles of hexaploid white oat. Parents and the segregating population (in the F2 and F3 generations) were evaluated in regard to the presence and distribution of naked grains in panicles of individual oat plants. For each plant, a drawing of the main panicle was developed. From the drawings obtained in the progenies of the F2 population, six distinct phenotypic classes were produced. The expected phenotypic proportion of 3:9:4 (naked:segregating:hulled) was that which best fit by the Chi-square test. In the F3 generation, the results showed agreement with the hypothesis observed in the F2 generation. The naked trait in oat is passed on by two genes and the greatest expression of this trait occurs in the upper third of the panicles. Expression of this trait in oats is not complete, even in homozygous genotypes

Functionalized Mesoporous SBA-15 with CeF3: Eu3+ Nanoparticle by Three Different Methods: Synthesis, Characterization, and Photoluminescence

Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF3: Eu3+ phosphor layer on its surface (denoted as CeF3: Eu3+/SBA-15/IS, CeF3: Eu3+/SBA-15/SI and CeF3: Eu3+/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF3: Eu3+ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce3+ and the central Eu3+ ion. They show the characteristic emission of Ce3+ 5d → 4f (200–320 nm) and Eu3+5D0 → 7FJ(J = 1–4, with 5D0 → 7F1 orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF3: Eu3+/SBA-15/SS exhibits the characteristic emission of Eu3+ ion under UV irradiation with higher luminescence intensity than the other materials

Effect of Ca2+ Channel Block on Glycerol Metabolism in Dunaliella salina under Hypoosmotic and Hyperosmotic Stresses

The effect of Ca2+ channel blockers on cytosolic Ca2+ levels and the role of Ca2+ in glycerol metabolism of Dunaliella salina under hypoosmotic or hyperosmotic stress were investigated using the confocal laser scanning microscope (CLSM). Results showed that intracellular Ca2+ concentration increased rapidly when extracellular salinity suddenly decreased or increased, but the increase could be inhibited by pretreatment of Ca2+ channel blockers LaCl3, verapamil or ruthenium red. The changes of glycerol content and G3pdh activity in D. salina to respect to hypoosmotic or hyperosmotic stress were also inhibited in different degrees by pretreatment of Ca2+ channel blockers, indicating that the influx of Ca2+ via Ca2+ channels are required for the transduction of osmotic signal to regulate osmotic responses of D. salina to the changes of salinity. Differences of the three blockers in block effect suggested that they may act on different channels or had different action sites, including influx of Ca2+ from the extracellular space via Ca2+ channels localized in the plasma membrane or from intracellular calcium store via the mitochondrial. Other Ca2+-mediated or non-Ca2+-mediated osmotic signal pathway may exist in Dunaliella in response to hypoosmotic and hyperosmotic stresses