Detecting exoplanets with FAST?

We briefly review the various proposed scenarios that may lead to nonthermal radio emissions from exoplanetary systems(planetary magnetospheres, magnetosphere-ionosphere and magnetospheresatellite coupling, and star-planet interactions), and the physical information that can be drawn from their detection. The latter scenario is especially favorable to the production of radio emission above 70 MHz. We summarize the results of past and recent radio searches, and then discuss FAST characteristics and observation strategy, including synergies. We emphasize the importance of polarization measurements and a high duty-cycle for the very weak targets that radio-exoplanets prove to be.     

遥感和GIS技术应用于伊拉克南部Basrah省土地利用/覆盖变化及城市扩张研究(英文)

In recent years, land use/cover dynamic change has become a key subject that needs to be dealt with in the study of global environmental change. In this paper, remote sensing and geographic information systems (GIS) are integrated to monitor, map, and quantify the land use/cover change in the southern part of Iraq (Basrah Province was taken as a case) by using a 1:250 000 mapping scale. Remote sensing and GIS software were used to classify Landsat TM in 1990 and Landsat ETM+ in 2003 imagery into five land use and land cover (LULC) classes: vegetation, sand, urban area, unused land, and water bodies. Supervised classification and normalized difference build-up index (NDBI) were used respectively to retrieve its urban boundary. An accuracy assessment was performed on the 2003 LULC map to determine the reliability of the map. Finally, GIS software was used to quantify and illustrate the various LULC conversions that took place over the 13-year span of time. Results showed that the urban area had increased by the rate of 1.2% per year, with area expansion from 3 299.1 km² in 1990 to 3 794.9 km² in 2003. Large vegetation area in the north and southeast were converted into urban construction land. The land use/cover changes of Basrah Province were mainly caused by rapid development of the urban economy and population immigration from the countryside. In addition, the former government policy of “returning farmland to transportation and huge expansion in military camps” was the major driving force for vegetation land change. The paper concludes that remote sensing and GIS can be used to create LULC maps. It also notes that the maps generated can be used to delineate the changes that take place over time. Supported by the Al-Basrah University, Iraq, the Geo-information Science and Technology Program (No. IRT 0438)China).     

非火山型大陆边缘从张裂到破裂分离时岩石圈伸展：流变学、蛇纹岩化和对称性

在过去二十年中,大陆破裂分离过程的对称性和非对称性存在许多争论,一些作者提出了非对称性的简单剪切模式,另一些作者则强调对称性、纯剪切模型和部分二者的结合。在非火山型边缘大陆下的地幔上涌侵蚀使得一些作者认为简单剪切模式是正确的,但缺乏足够的支持证据。从共轭边缘对的沉降史之证据是可疑的,这些边缘详细的地壳和岩石圈结构不十分了解,不能得到确定的结论。在Porcupine盆地,这里大陆破裂分离的最后阶段是可知的,不对称构造的发育是存在的,它们显然与在随着地壳完全脆裂过程中地壳和地幔的后期耦合作用有关。这和理论模拟的结果是一致的,只有当地壳和地幔紧密耦合时,仅仅在岩石圈尺度上可预测不对称模型的发育。然而,对在地幔连续剥露过程中是否一直是存在这样不对称性仍不清楚。     

Chronic exposure of Leptocheirus plumulosus to Baltimore Harbor sediment: bioenergetic and population-level effects

We investigated the long-term effects of contaminants in sediment from Baltimore Harbor, MD, USA, on a burrowing amphipod (Leptocheirus plumulosus) via a full life-cycle laboratory exposure. Contaminants in the Baltimore Harbor sediment included PAHs (10,800 ng/g), PCBs (152 ng/g), and heavy metals (including As, Cd, Cu, Pb, Hg, Ni, and Zn). Exposures were initiated with neonate amphipods, placed in microcosms containing either contaminated or reference sediment, and were maintained for 42 days, allowing ample time for the initial cohort to mature and reproduce. At the end of the exposure period, the populations of amphipods were surveyed to ascertain the number and size of amphipods in each size class (neonate, juvenile, and adult), and bioenergetic measurements were performed on adults, including metabolic rate, lipid content, and fecundity. Contaminated sediment from Baltimore Harbor caused lower growth and reproductive rates; in Baltimore Harbor sediment, the average dry weight of amphipod offspring in each size class was significantly lower and there were less than one-third as many individuals in each size class, compared to reference sediment. By the end of the exposure, the total amphipod biomass in Baltimore Harbor sediment was less than one quarter of that in reference sediment. On average, gravid females in reference sediment produced at least twice as many viable offspring as those in contaminated sediment. Adult male amphipods in Baltimore Harbor sediment possessed significantly lower lipid concentrations. Lipid content in neonates also appeared to be negatively affected by parental exposure to contaminants. Metabolic rate was elevated in adult amphipods exposed to Baltimore Harbor sediment. Overall, the results suggest that contaminated sediment conditions in the urban estuary may chronically affect L. plumulosus by diverting energy from production to maintenance pathways, resulting in slower growth and reduced fecundity, and ultimately leading to retarded population growth rates. The results of this study reinforce the need for long-term toxicological exposures to reveal chronic effects.     

Production of the Blood Pressure Lowing Peptides from Brown Alga （ Undaria pinnatifida ）

Brown alga （ Undaria pinnatifida） was treated with alginate lyase and hydrolyzed using 17 kinds of proteases and the inhibitory activity of the hydrolysates for the angiotensin-I-converting enzyme （ACE） was measured. Four hydrolysates with potent ACE-inhibitory activity were administered singly and orally to spontaneously hypertensive rats （SHRs）. The systolic blood pressure of SHRs decreases significantly after single oral administration of the brown alga hydrolysates by pro- tease S ＇ Amano＇ （from Bacillus stearothermophilus） at the concentration of 10 （mg protein） （kg body weight）^ - 1. In the 17 weeks of feeding experiment, 7-week-old SHRs were fed standard diet supplemented with the brown alga hydrolysates for 10 weeks. In SHRs fed 1.0 and 0.1% brown alga hydrolysates, elevating of systolic bloodpressure was significantly suppressed for 7 weeks. To elucidate the active components, the brown alga hydrolysates were fractionated by 1-butanol extraction and HPLC on a reverse-phase column. Seven kinds of ACE-inhibitory peptides were isolated and identified by amino acid composition analysis, sequence analysis, and LC-MS with the results Val-Tyr, Ile-Tyr, Ala-Trp, Phe-Tyr, Val-Trp, Ile-Trp, and Leu-Trp. Each peptide was determined to have an antihypertensive effect after a single oral administration in SHRs. The brown alga hydrolysates were also confirmed to decrease the blood pressure in humans.     

联邦德国逆城市化强化原因之研究

一些详尽的研究认为,逆城市化现象于20世纪70年代出现于西欧,并同时扩散到其它一些高度工业化的国家。逆城市化一般指人口从大城市或人口稠密区向较小城市或人口低密度区的扩散。更准确地讲,逆城市化可以用区域人口规模与净移民率间的负相关关系来衡量。对逆城市化的原因,有三种不同的观点。一种观点强调就业机会空间分布差异的重要性,认为逆城市化是个就业导向的过程。     

5个CSS源50cm VLBI观测数据的再处理

本文给出了全球VLBI网50cm数据成图再处理的部分结果.样本包括5个CSS射电源:3C43、3C138、3C186、3C216和3C237.为了便于比较,同时给出了二次成图处理后的图象.通过对这些源的形态描述,并且通过与其它波段高分辨率图的对照,核实了再处理图上各子源的位置,这些低频观测细节,对更好地了解CSS源的本质无疑是十分有益的。     

A Possible Periodicity in the Radio Light Curves of 3C 454.3

During the period 1966.5–2006.2 the 15GHz and 8GHz light curves of 3C 454.3 (z = 0.859) show a quasi-periodicity of ～12.8 yr (～6.9 yr in the rest frame of the source) with a double-bump structure. This periodic behaviour is interpreted in terms of a rotating double-jet model in which the two jets are created from the black holes of a binary system and rotating with the period of the orbital motion. The periodic variations in the radio fluxes of 3C 454.3 are suggested to be mainly due to the lighthouse effects (or the variation in Doppler boosting) of the precessing jets caused by the orbital motion. In addition, variations in the rate of mass accreting onto the black holes may be also involved.