Effect of burrowing activity of root vole (Microtus oeconomus Pallas) on plant diversity in alpine meadow

Herbivory and burrowing activity of mammals may influence the species composition and diversity of plant communities. The effect of corridors and holes systems constructed by root vole (Microtus oeconomus Pallas) on the plant species diversity was studied in the habitat of high - mountain meadow (3250 in a.s.l in Qinghai-Tibet Plateau, China). By using grid method, these disturbances were studied on 16 plots (100 cm x 100 cm) distributed in 4 transects in studied area, in August 2000 and 2001. The disturbance intensity index, D, was calculated as the percent of the ground surface disturbed by voles in the study area. Plant species were identified and counted on the same plots. In total 46 plant species were identified - 39% of this number was considered as sensitive to the vole disturbances as their occurrence and/or abundance decreased along the disturbance intensity. Generally, a significantly negative correlation (r = - 0.911 P < 0.01) between vole aboveground disturbances and plant species diversity (H') was found. The results suggest that root vole ground disturbances, especially in the form of actively utilized holes and corridors have significantly negative influence on plant species diversity in high-mountain grassland habitat.

Breeding behavior under temporal risk of predation in male root voles (Microtus oeconomus)

We examined breeding behavior responses of male root votes (Microtus oeconomus) to temporal risk of predation by using acute and chronic exposure to predator odor. The 2 series of exposure experiments provided 2 types of temporal patterns of risk: continuous safety with a brief period of risk and Sustained risk with a brief period of safety. Male root votes that were acutely exposed to predator odor for I h suppressed their breeding behavior, but bred immediately after exposure to control odor for I h. Those chronically exposed to predator odor for 20 days maintained behavioral suppression during the 1-h period of exposure to control odor. Acutely exposed males did not change their physiological patterns of breeding, but those chronically exposed to predator odor had reduced testosterone concentration and epididymis index. Our results indicate that breeding behavior in a given situation depends on the overall patterns of risk experienced by male root votes, and the acute and chronic stress responses that affect reproduction are responsible for different behavioral responses to the 2 types of temporal patterns of risk. We also discuss the reasons for conflicting results about breeding suppression of votes between previous studies in the laboratory and the field.

Local warming about 1.3 degrees C in alpine meadow has no effect on root vole (Microtus oeconomus L.) population during winter

The influence of air and soil warming on root vole (Microtus oeconomus L.) population was studied in winter period in top open chambers (OTC) (0.8-1.8 m(2) warmed by conical fiberglass material and situated in alpine meadow (3250 m) at Qinghai-Tibet Plateau, China. The OTCs were distributed on an area of 30 x 30 m of experimental warming site; another site of the same area was a control one. The root vole population was investigated on two pairs of sites in "low-grazing" and "high-grazing" (by sheep) parts of the meadow; mark-recapture method was used. The winter-season averaged air and soil temperature inside of the chambers were 1.3 degrees C higher than the temperature outside the chambers. The warming in the chambers had no statistically significant effect on root vole numbers, on average body mass of individual, and on average body mass of males and females. In conclusion, as small as 1.3 degrees C warming of soil and air introduced locally and on small (several m(2)) scale, in the alpine meadow habitat in winter period, has possibly no effect on root vole numbers and biomass.

指数矩阵近似计算在地震波场延拓中的应用

Seismic wave field numerical modeling and seismic migration imaging based on wave equation have become useful and absolutely necessarily tools for imaging of complex geological objects. An important task for numerical modeling is to deal with the matrix exponential approximation in wave field extrapolation. For small value size matrix exponential, we can approximate the square root operator in exponential using different splitting algorithms. Splitting algorithms are usually used on the order or the dimension of one-way wave equation to reduce the complexity of the question. In this paper, we achieve approximate equation of 2-D Helmholtz operator inversion using multi-way splitting operation. Analysis on Gauss integral and coefficient of optimized partial fraction show that dispersion may accumulate by splitting algorithms for steep dipping imaging. High-order symplectic Pade approximation may deal with this problem, However, approximation of square root operator in exponential using splitting algorithm cannot solve dispersion problem during one-way wave field migration imaging. We try to implement exact approximation through eigenfunction expansion in matrix. Fast Fourier Transformation (FFT) method is selected because of its lowest computation. An 8-order Laplace matrix splitting is performed to achieve a assemblage of small matrixes using FFT method. Along with the introduction of Lie group and symplectic method into seismic wave-field extrapolation, accurate approximation of matrix exponential based on Lie group and symplectic method becomes the hot research field. To solve matrix exponential approximation problem, the Second-kind Coordinates (SKC) method and Generalized Polar Decompositions (GPD) method of Lie group are of choice. SKC method utilizes generalized Strang-splitting algorithm. While GPD method utilizes polar-type splitting and symmetric polar-type splitting algorithm. Comparing to Pade approximation, these two methods are less in computation, but they can both assure the Lie group structure. We think SKC and GPD methods are prospective and attractive in research and practice.

Phase transformation in the surface region of zirconia detected by UV Raman spectroscopy

The phase transformation of zirconia from tetragonal to monoclinic is characterized by UV Raman spectroscopy, visible Raman spectroscopy, and XRD. Electronic absorption Of ZrO2 in the UV region makes UV Raman spectroscopy more sensitive at the surface region than XRD or visible Raman spectroscopy. Zirconia changes from the tetragonal phase to the monoclinic phase with calcination temperatures elevated and monoclinic phase is always detected first by UV Raman spectroscopy for the samples calcined at lower temperatures than that by XRD and visible Raman spectroscopy. When the phase of zirconia changes from tetragonal to monoclinic, the slight changes of the phase at very beginning can be detected by UV Raman spectroscopy. UV Raman spectra clearly indicate that the phase transition takes place initially at the surface regions. It is found that the phase change from tetragonal to monoclinic is significantly retarded when amorphous Zr(OH)(4) was agglomerated to bigger particles and the particle agglomeration of amorphous zirconium hydroxide is beneficial to the stabilization of t-ZrO2 phase.

An Accountable Source-To-Source Transformation System

Though one is led to believe that program transformation systems which perform source-to-source transformations enable the user to understand and appreciate the resulting source program, this is not always the case. Transformations are capable of behaving and/or interacting in unexpected ways. The user who is interested in understanding the whats, whys, wheres, and hows of the transformation process is left without tools for discovering them. I provide an initial step towards the solution of this problem in the form of an accountable source-to-source transformation system. It carefully records the information necessary to answer such questions, and provides mechanisms for the retrieval of this information. It is observed that though this accountable system allows the user access to relevant facts from which he may draw conclusions, further study is necessary to make the system capable of analyzing these facts itself.

Analysis of the estrogenic components in kudzu root by bioassay and high performance liquid chromatography

The estrogenic activity of the Chinese herb kudzu root was investigated by a recombinant yeast screening assay (YES). Isoflavones are the main components in the plant, of which puerarin is the most abundant one. The kudzu root extract was separated into four fractions according to the polarity. The crude extract and its sub-fractions, except the water fraction, showed clear estrogenic activity and the potencies were in the range of 10(-3) to 10(-1) g/l. The ligand potency was used to compare the estrogenic activity of these fractions. The crude extract and its sub-fractions were further analyzed by high performance liquid chromatography (HPLC) to correlate the activity and the active components. Bioassay and chemical analysis showed that theoretical estrogenic activity expressed as equivalent 17 beta-estradiol concentration or the cumulative effects are comparable to that experimentally determined by YES. The results showed that the high content of isoflavones as well as the high estrogenic activity could make kudzu root extract an interesting candidate for hormone replacement therapy. (c) 2005 Elsevier Ltd. All rights reserved.

Capillary array electrophoresis for the research of asymmetric transformation reaction of L-proline to D-proline

One asymmetric transformation reaction Of L-proline (L-Pro) to D-proline was studied by a home-made capillary array electrophoresis (CAE) for the first time. The aldehyde catalysts and the organic acid solvents for the asymmetric transformation reaction were rapidly screened and the enantiomeric excess values of the asymmetric product Of L-Pro were directly obtained from the electrophoretogram of CAE.