Estradiol and estriol suppress CYP1A expression in rainbow trout primary hepatocytes

Hepatic levels of the pollutant inducible enzyme, CYP1A, are strongly suppressed in spawning female fish, a phenomenon attributed to high plasma levels of the female sex steroid hormone, estradiol. To evaluate the contribution of estrogen metabolites to estradiol-mediated CYP1A regulation, we treated primary hepatocytes isolated from juvenile rainbow trout (Oncorhynchus mykiss) with vehicle, 17beta-estradiol, or the estrogen metabolite, estriol, alone and in combination with each other and with the potent CYP1A inducer, benzo[a]pyrene (B[a]P). We found dose-dependent suppression of B[a]P-induced CYP1A activity by both steroids relative to controls. At 10(-7) M doses, estradiol and estriol suppressed B[a]P-induced CYP1A activity by 3- and 2-fold, respectively. Although not statistically significant, mean basal CYP1A activity levels were 15- and 13-fold lower in estradiol and estriol treated hepatocytes, respectively, relative to vehicle treated controls. Combining doses of estradiol and estriol failed to produce synergistic suppression of either basal or B[a]P-induced CYP1A activity relative to treatment with either steroid alone. The observed suppression is well below the often strong suppression observed in spawning female fish. We conclude that factors in addition to estradiol and estriol are likely involved in producing sexual dimorphism in CYP1A expression observed in spawning fish.     

时距平面剩余时差选择加权叠加压制多次波方法及效果

一个CDP道集经动校正后,多次波仍存在剩余时差δt,它随炮检距呈抛物线变化。由δt的变化即可求出多次波剩余波数△K的分布规律。据此,可设计一个理想的叠加剩余波数响应,用于动校正后的CDP道集的加权叠加。在t～x平面选择δt,即可改变叠加剩余波数响应,从而改变各道的加权系数,实现最佳压制多次波的效果。     

Mechanical shaking and soil water affect the growth of Psammochloa villosa in the Mu Us Sandland

The Mu Us Sandland is basically characterized by water shortage and high wind. Thus, wind-induced mechanical perturbation (MP) and soil water availability are likely to interact to affect plant growth. Since high water availability and MP can induce responses that are in the opposite direction, we hypothesized that MP effects on perennial grasses might be mitigated by increased soil water availability in the Mu Us Sandland. We counducted an experiment in which seedlings of Psammochloa villosa were subjected to two levels of MP (non-MP vs. MP 1 min d⁻¹) and two levels of water availability (200 ml d⁻¹vs. 400 ml d⁻¹) and measured three plant traits. MP significantly decreased plant height, total biomass, and root/shoot ratio. There were significant interactions between MP and soil water availability on plant height and root/shoot ratio. These findings imply that MP alone is a stressful factor for P. villosa and MP effects on its growth can be partially mitigated by increased soil water availability, and also suggest that P. villosa may respond to MP in a way that allows plants to survive in the windy semiarid environments.     

冷涡条件下雹云的雷达回波分析及冰雹预报

利用一次冷涡南下引起的两次强对流天气的数字化雷达回波资料，结合黄河三角洲地区的天气学资料，对比分析了两交冰雹及冰雹和暴雨回波的异同点，为强对流天气的临近预报和人工防雹提供参考。     

Amplification or suppression: Social networks and the climate change—migration association in rural Mexico

Increasing rates of climate migration may be of economic and national concern to sending and destination countries. It has been argued that social networks—the ties connecting an origin and destination—may operate as “migration corridors” with the potential to strongly facilitate climate change-related migration. This study investigates whether social networks at the household and community levels amplify or suppress the impact of climate change on international migration from rural Mexico. A novel set of 15 climate change indices was generated based on daily temperature and precipitation data for 214 weather stations across Mexico. Employing geostatistical interpolation techniques, the climate change values were linked to 68 rural municipalities for which sociodemographic data and detailed migration histories were available from the Mexican Migration Project. Multi-level discrete-time event-history models were used to investigate the effect of climate change on international migration between 1986 and 1999. At the household level, the effect of social networks was approximated by comparing the first to the last move, assuming that through the first move a household establishes internal social capital. At the community level, the impact of social capital was explored through interactions with a measure of the proportion of adults with migration experience. The results show that rather than amplifying, social capital may suppress the sensitivity of migration to climate triggers, suggesting that social networks could facilitate climate change adaptation in place.     

On splitter plate coverage for suppression of vortex-induced vibrations of flexible cylinders

Experimental results show how vortex-induced vibration (VIV) amplitudes of flexible cylinders can be reduced up to a 90% by covering less than half of the length of the cylinder with splitter plates elastically mounted to the surface of the cylinder.The VIV amplitude reduction takes place along with drag coefficient reductions of up to a 50% for the reduced velocities investigated.     

Identification of genes expressed in juvenile Haliotis rufescens in response to different copper concentrations in the north of Chile under controlled conditions

This study reports molecular markers potentially associated with resistance or sensitivity to the impact of copper in juvenile red abalone, Haliotis rufescens, in the north of Chile under experimental conditions. Genomic analysis was made applying subtractive hybridization libraries (SSH) to identify genes up-and down regulated during cooper exposure in abalone over periods of 12 and 168 h exposed to 2.5 and 10 μg/L of Cu⁺². Results obtained from the SSH library revealed 368 different sequences regulated by copper, that correspond to eight major physiological functions. The validation of these sequences obtained by SSH as well as their expression kinetics were made by PCR in real time on 14 potential genes regulated by metal stress. This study provides information for the characterization of potential genomic markers that may be used in future environmental monitoring and to investigate new mechanisms of stress to copper in this commercially important marine species.     

连云洪市一次降雹过程个例的物理检验和数值模拟研究

本文对1998年8月29日发生连云港地区的降雹过程的分析，从物理检验和数值模拟角度进行了分析研究，研究表明，该降雹过程经人工催化作业后，地面降雹减少，降雨增加，初步论证了防雹的效果。     

Differential gene expression in the brain of Sebastiscus marmoratus in response to exposure to polychlorinated biphenyls (PCBs)

Effects of exposure to polychlorinated biphenyls (PCBs) on Sebastiscus marmoratus were investigated using a suppression subtractive hybridization method. A total of 108 gene sequences were identified as having the potential for being differentially expressed, and 45 could be identified with homologous database sequences. Functions with which they were associated included long-term potentiation and neurotransmitter release, neuroendocrine, mitosis and cell proliferation, energy-related metabolism, general metabolism, signal protein, hemopoiesis system, immune system, and structure. The expression of 17 of these genes was analyzed in the brain using real time fluorescent quantitative PCR. The present study provided a basis for studying the response of fish to PCB exposure and allowed the characterization of new potential neurotoxicol biomarkers of PCB contamination in seawater.     

基于波动方程预测和双曲Radon变换联合压制表面多次波

基于波动方程预测的表面多次波压制方法可处理复杂地下介质的地震资料,但计算成本较高.基于滤波的多次波压制方法计算效率较高,但其成功应用仅局限于一次波和多次波有明显时差差别的地震数据,对来自速度逆转等复杂介质数据则较难获得满意的压制效果.本文将波动方程预测的反馈迭代法和滤波法有效结合,采用GPU(图形处理器)和CPU协同并行加速计算粗略预测表面多次波,随后在双曲Radon域比较分析原始数据和预测的多次波,设计合理有效的Butterworth型自适应滤波器,滤出原始数据Radon域中的多次波能量,进行Radon反变换后,在时空域将多次波从原始数据中减去,得多次波压制结果.文中对理论模拟的单炮数据、复杂的SMAART模型以及实际地震数据进行了计算,结果表明,结合基于波动方程预测和双曲Radon变换的方法有效突破了两种方法各自的局限性,可高效高精度地压制复杂地下介质的表面多次波.