Modelling soil erodibility in mountain rangelands of southern Kyrgyzstan

Soil erosion in mountain rangelands in Kyrgyzstan is an emerging problem due to vegetation loss caused by overgrazing. It is further exacerbated by mountain terrain and high precipitation values in Fergana range in the south of Kyrgyzstan. The main objective of this study was to map soil erodibility in the mountainous rangelands of Kyrgyzstan. The results of this effort are expected to contribute to the development of soil erodibility modelling approaches for mountainous areas. In this study, we mapped soil erodibility at two sites, both representing grazing rangelands in the mountains of Kyrgyzstan and having potentially different levels of grazing pressure. We collected a total of 232 soil samples evenly distributed in geographical space and feature space. Then we analyzed the samples in laboratory for grain size distribution and calculated soil erodibility values from these data using the Revised Universal Soil Loss Equation (RUSLE) K-factor formula. After that, we derived different terrain indices and ratios of frequency bands from ASTER GDEM and LANDSAT images to use as auxiliary data because they are among the main soil forming factors and widely used for prediction of various soil properties. Soil erodibility was significantly correlated with channel network base level (geographically extrapolated altitude of water channels), remotely sensed indices of short-wave infrared spectral bands, exposition, and slope degree. We applied multiple regression analysis to predict soil erodibility from spatially explicit terrain and remotely sensed indices. The final soil erodibility model was developed using the spatially explicit predictors and the regression equation and then improved by adding the residuals. The spatial resolution of the model was 30 m, and the estimated mean adjusted coefficient of determination was 0.47. The two sites indicated different estimated and predicted means of soil erodibility values (0.035 and 0.039) with a 0.05 significance level, which is attributed mainly to the considerable difference in elevation.     

数字电视频道系统在顺德农业信息服务中的应用

顺德农业数字电视频道系统,包括农业政务、科技、市场信息的文本、图片、流媒体视频信息点播,通过手机与电视双向互动的农业供求即时通.该系统具有信息到户、操作便利、随时查看、随意选择、更新迅速、双向互动的先进性,易于在沿海发达地区的农村基层推广普及.从根本上解决农业信息服务的"最后一公里"问题.文章还介绍了目前基层农村的农业信息服务现状、缺陷,也介绍了推广新系统将带来的社会和经济效益.     

张家口市河流筑坝与硬化的生态系统健康影响研究

研究筑坝与硬化对河流生态系统健康的影响,为人工改造河流的生态修复和管理优化提供科学依据。以张家口市清水河—洋河干流5个不同程度筑坝与硬化的河段为研究对象,构建了包括河道结构、河床底质、水文特征、水质参数和水生生物5类指标的河流生态系统健康指数(RHI),评估了筑坝与硬化对河流健康的影响。结果表明,河道轻微疏浚或具拦砂坝河段的生态系统健康等级为好(RHI 30~40),具溢流堰河岸硬化河段为中等健康(RHI 20~30),筑坝和河床河岸全硬化的河段生态系统健康等级为差(RHI 10~20)。筑坝与硬化改变河流物理结构,进而影响河床底质组分和水文特征,其与RHI的变化显著相关(P<0.05),是损害河流生态系统健康的主要原因;此外,总磷、有机质污染及较低的水生生物多样性对河流的健康均有不利影响,仅在夏季植物大量生长和污染物质被稀释时,RHI有所提高。为了改善河流生态系统的健康状况,需要恢复自然的河岸和缓冲带,改善河流水动力,并加强外源污染控制。     

Effects of varying dietary compositions using common feed ingredients on growth and feed efficiency of pond‐raised channel catfish Ictalurus punctatus (Rafinesque)

Two experiments were conducted to evaluate various ingredient combinations in a 28% or 32% protein diet for optimum performance of channel catfish Ictalurus punctatus. All diets contained soybean meal and corn, but with or without cottonseed meal, wheat middlings or fish meal (FM). Channel catfish fingerlings were stocked into 0.04 ha earthen ponds at 18 530 fish ha^?1. Fish were fed one of eight diets once daily to apparent satiation for two growing seasons. Results demonstrated that the dietary ingredient composition used had significant effects on fish performance, but magnitude of differences was relatively small. Overall, diets containing FM resulted in greater weight gain (Experiments 1 and 2) and lower feed conversion ratio (Experiment 1) than fish fed all‐plant diets. However, certain combinations of plant ingredients provided the similar fish growth as some diets containing FM. There were no significant differences in weight gain between fish fed soybean meal–corn or soybean meal–corn–wheat middlings‐based diets with cottonseed meal or FM. The use of wheat middlings in the diet had no significant effects on fish production characteristics.     

Evaluation of a 4‐h static copper sulphate treatment against experimental infection of Flavobacterium columnare in channel catfish (Ictalurus punctatus)

The efficacy of copper sulphate (CuSO₄) against the early stages of an experimental acute infection of Flavobacterium columnare in channel catfish (Ictalurus punctatus) was evaluated. Fish were challenged, by waterborne exposure to F. columnare in an ultra‐low flow‐through water delivery system, and treated with CuSO₄ at 4.2 and 2.1 mg L^?1 at 5.5 h post challenge for 4 h. Bacterial challenged non‐treated fish acted as a positive control and non‐challenged non‐treated fish acted as a negative control. Fish challenged with F. columnare and treated with CuSO₄ at 4.2 and 2.1 mg L^?1 post challenge had mortalities of 6.4% and 18.3%, respectively, compared with the positive control, which had 90.2% mortality. The mortality of challenged fish treated with CuSO₄ at 4.2 and 2.1 mg L^?1 was significantly different from the positive control. There was no significant difference between the mortalities of the 4.2 and 2.1 mg L^?1 treatments. The results suggest that CuSO₄ has clear therapeutic value against columnaris infections.     

Multi‐channel visual evoked potential as an ancillary tool to diagnose intraorbital optic nerve lesions

Multi‐channel visual evoked potential (MVEP) recording method was used to assist in diagnosing a 4‐month‐old Chinese Albino rabbit with an intraorbital mass. Subcutaneous MVEP of its both eyes were recorded simultaneously using 16 electrodes (4 × 4) multi‐channel array. Analysis of the cortical potential landscapes (CPL) showed that the conduction function of right eye was remarkably impaired in terms of decreased amplitudes and prolonged latencies. Specific side‐dominant distribution asymmetry of the decreased MVEP amplitudes indicated that the temporal side of the optic nerve (ON) was severely involved. Overall prolonged latencies of the CPL without side differences suggested that the functional impairment could have been caused by the mechanical compression exerted by an intraorbital mass. Surgical removal procedures confirmed that the mass was located temporally to the ON. Pathological examination provided a final diagnosis of a giant polycystic mucocele. Beyond its significance as a standard tool to assess functional changes of the visual pathway, MVEP recordings might assist locating intraorbital lesions that involve the ON by careful analysis of abnormal CPLs.     

Modulation of sodium channels by the oxadiazine insecticide indoxacarb and its N-decarbomethoxylated metabolite in rat dorsal root ganglion neurons

The effects of the oxadiazine insecticide indoxacarb and its N-decarbomethoxylated metabolite (DCJW) on tetrodotoxin-resistant (TTX-R) voltage-gated sodium channels in rat dorsal ganglion neurons were studied using the whole-cell patch clamp technique. Indoxacarb and DCJW suppressed the peak amplitude of action potentials, and DCJW exhibited a faster time course and higher potency than indoxacarb in the blocking effects. In voltage-clamp experiments, indoxacarb and DCJW suppressed TTX-R sodium currents in a time-dependent manner without a steady-state level of suppression. IC50 values for indoxacarb and DCJW on TTX-R sodium currents were estimated to be 10.7 and 0.8 microM after 25 min of bath application, respectively. DCJW was about 10 times more potent than indoxacarb in blocking TTX-R sodium currents. Although the suppressive effects of indoxacarb were partially reversible after washout with drug-free external solution, no recovery of sodium current was observed in DCJW treated neurons after prolonged washout. In current-voltage relationships, both indoxacarb and DCJW blocked the sodium currents to the same degree in the entire range of membrane potentials. The sodium conductance-voltage curve was not shifted along the voltage axis by indoxacarb and DCJW at 10 microM. In contrast, the steady-state inactivation curves were shifted in the hyperpolarizing direction by indoxacarb as well as by DCJW. Based on these results, it was concluded that indoxacarb and DCJW potently blocked the TTX-R sodium channel in rat DRG neurons with hyperpolarizing shifts of the steady-state inactivation curves, suggesting preferential association of the insecticides to the inactivated state of sodium channels. The small structural variation between indoxacarb and DCJW resulted in clear differences in potency for blocking sodium channels and reversibility after washout.     

我国农村资金外流分析

在中国，“二元经济结构”导致资本发生流动偏好，资本流动偏好又加快农村资金外流的规模与速度。因此，减缓叶：国农村资金外流必须依据资本流动偏好规律，改善农村投资环境，完善农村各种金融机构职能。从而改变资金流动方向，引导资金向农村回流。     

分叉角与回转半径对双向流道灌水器水力性能影响模拟研究

为研究双向流道灌水器水力性能，将其结构单元作为研究对象，以分叉角和回转半径两个结构参数为影响因素，采用正交试验设计16种结构参数组合方案，利用计算流体动力学软件Ansysfluent对流道内部流体的流动状态进行数值模拟，通过量纲分析建立流道结构参数与流道单元局部水头损失的回归模型。结果表明：双向流道单元局部水头损失与分叉角、回转半径和流道流速有关，分叉角与局部水头损失呈负相关关系，回转半径和速度与局部水头损失呈正相关关系；当入口流速为固定值时，分叉角为32.4°、回转半径为1.72 mm，流道单元局部水头损失最大；当设置10个流道单元时，交叉排列方式组合的灌水器流态指数较优。     

论销售渠道的创新

传统的销售渠道在渠道体制、渠道成员的关系及渠道运作上均存在问题,在市场营销环境已发生根本性变化的情况下,销售渠道创新已成为企业的必然选择。在分析传统销售渠道存在的问题及市场营销环境变化对销售渠道要求的基础上,就销售渠道如何创新提出了意见和建议。