Crab脉冲星巨脉冲辐射等待时间分布的非稳态泊松模拟

利用中国科学院新疆天文台南山观测站26m射电望远镜,在中心频率1556MHz,对Crab脉冲星(PSR B0531+21)进行了长达12.6h的连续观测,观测带宽为512MHz,时间分辨率为32μs,研究了巨脉冲辐射的等待时间分布特征.观测共探测到2097个信噪比大于10的巨脉冲,对应的流量密度大于100Jy.巨脉冲的爆发率表现为高度的间歇性,在较短的时间内具有较高的爆发率,在相对长的宁静期内巨脉冲的爆发率较低,尤其是中间脉冲相位内的巨脉冲爆发.相邻两个巨脉冲的等待时间分布表现为幂律分布特征,可以用一个非稳态的泊松过程进行模拟,这表明巨脉冲的爆发是一种独立的随机事件.此外,主脉冲和中间脉冲相位上的巨脉冲具有不同的等待时间分布特征,这意味着脉冲星不同磁极的巨脉冲辐射机制可能是不同的.这些观测结果对于理解脉冲星的射电辐射机制具有重要意义.

多发性骨髓瘤CRAB症状与抗氧化酶活性的相关性分析

目的:探讨多发性骨髓瘤(MM)患者CRAB症状的常见临床指标与抗氧化酶活性之间的联系。方法:比色法检测44名骨髓瘤患者及12名非恶性血液病患者骨髓上清中的过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPX)和超氧化物歧化酶(SOD)的活性,分析两组抗氧化酶的活性差异以及骨髓瘤组中抗氧化酶的活性与血钙、血肌酐(Scr)、血红蛋白(Hb)、碱性磷酸酶(ALP)及骨破坏区域数量的关系。结果:与对照组相比,骨髓瘤患者的抗氧化酶活性更低(P<0.05)。当血钙、ALP的浓度高于正常水平,Hb低于85 g/L及存在多个骨破坏区域时,抗氧化酶CAT、SOD和GPX的活性明显降低(P<0.05);当Scr高于正常水平时,GPX活性明显降低(P<0.05)。回归分析结果显示,CAT、SOD、GPX与血钙(r=-0.538,r=-0.456,r=-0.431)、Scr(r=-0.342,r=-0.384,r=-0.463)和ALP(r=-0.551,r=-0.572,r=-0.482)均呈负性相关。结论:抗氧化酶CAT、SOD和GPX的活性在多发性骨髓瘤患者中下降,并且与CRAB症状的常见临床指标(血钙、Scr、ALP)呈负性相关,或许可以通过提高骨髓瘤患者体内的抗氧化酶活性来治疗CRAB症状。

Seasonal response of nitrogen exchange fluxes to crab disturbance at sediment-water interface in coastal tidal wetlands

Coastal wetlands are hotspots for nitrogen(N)cycling,and crab burrowing is known to transform N in intertidal marsh soils.However,the underlying mechanisms remain unclear.This study conducted field experiments and used indoor control test devices to investigate the seasonal response of nitrogen to crab disturbance at the sediment-water interface in coastal tidal flat wetlands.The results showed that crab disturbance exhibited significant seasonality with large seasonal differences in cave density and depth.Due to crab disturbance,nitrogen fuxes at the sediment-water interface were much greater in the box with crabs than in the box without crabs.In summer,NH-N showed a positive flux from the sediment to the overlying water,but NO2-N and NOg-N showed positive fluxes from the sediment to the overlying water only in early stages.In winter,NH-N showed a positive flux from the sediment to the overlying water,but NO-N and NO,-N both exhibited positive and negative fluxes.These results indicated that the presence of crab burrows can cause the aerobic layer to move downward by approximately 8-15 cm in summer and directly promote nitrification at the sediment surface.

Fast Two-dimensional Positioning Method of Crab Pulsar Based on Multiple Optimization Algorithms

In the two-dimensional positioning method of pulsars, the grid method is used to provide non-sensitive direction and positional estimates. However, the grid method has a high computational load and low accuracy due to the interval of the grid. To improve estimation accuracy and reduce the computational load, we propose a fast twodimensional positioning method for the crab pulsar based on multiple optimization algorithms(FTPCO). The FTPCO uses the Levenberg–Marquardt(LM) algorithm, three-point orientation(TPO) method, particle swarm optimization(PSO) and Newton–Raphson-based optimizer(NRBO) to substitute the grid method. First, to avoid the influence of the non-sensitive direction on positioning, we take an orbital error and the distortion of the pulsar profile as optimization objectives and combine the grid method with the LM algorithm or PSO to search for the non-sensitive direction. Then, on the sensitive plane perpendicular to the non-sensitive direction, the TPO method is proposed to fast search the sensitive direction and sub-sensitive direction. Finally, the NRBO is employed on the sensitive and sub-sensitive directions to achieve two-dimensional positioning of the Crab pulsar. The simulation results show that the computational load of the FTPCO is reduced by 89.4% and the positioning accuracy of the FTPCO is improved by approximately 38% compared with the grid method. The FTPCO has the advantage of high real-time accuracy and does not fall into the local optimum.

Characterization of Hydroxyapatite Extracted from Crab Shell Using the Hydrothermal Method with Varying Holding Times

Hydroxyapatite(HA)is a bio ceramic commonly utilized in bone tissue engineering due to its bioactive and osteoconductive properties.Crab shells are usually disregarded as waste material despite their significant CaCO_(3) content,and have not been widely utilized in the synthesis of HA.This study aims to synthesize and analyze HA derived from crab shells using the hydrothermal method with different durations of holding time.This study utilized precipitated calcium carbonate(PCC)derived from crab shells.With a hydrothermal reactor set at 160℃ and varying holding times of 14(HA_14),16(HA_16),and 18(HA_18)h,a PCC and(NH4)2HPO4 mixture was used to synthesize HA.The synthesis results were analyzed using scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR),and X-ray diffraction(XRD)tests.This study has accomplished the synthesis of HA from crab shells.Nonetheless,the final product of synthesis still contained CaCO_(3) as an impurity.The prolonged hydrothermal holding time of 14 to 18 h resulted in a reduction of impurities while increasing the percentage of crystal weight and crystallite size of HA.Specimen CH_18 is the best-quality product generated in this study.This specimen produced HA with the highest percentage of crystal weight and crystallite size compared to the other specimens.Furthermore,specimen CH_18 exhibited the lowest concentration of impurities.The Ca/P ratio in this specimen was also the closest to 1.67.The Ca/P ratio,crystallite size,and crystal weight percentage of this specimen are 1.54,19.06 nm,and 99.1%,respectively.

Growth and Diet Utilization Efficiencies of Overwinter Juvenile Mud Crabs Fed with Different Diets

[Objectives]To study the utilization efficiency of different diets for juvenile Scylla paramamosain.[Methods]Low-value fish,shrimp,clam and clamworm were fed to overwintering young mud crabs,and the performance of the feed was evaluated by growth,feed utilization and energy allocation.[Results]Shrimp-fed mud crabs showed the best growth performance,while fish-fed mud crabs showed the worst growth performance and converted the least protein and energy for growth.Shrimp-fed mud crabs molted more frequently,and the dry matter mass and energy of Exuviation were significantly higher than those of fish-fed mud crabs.The shrimp-fed crabs also had significantly higher food intake than those fish-fed crabs.The order of feed conversion efficiency(FCE)of fish-fed mud crabs was Polychaete>clam>shrimp>fish,while the order of FCE calculated with FCE-P and FCE-E was Polychaete>clam>shrimp>fish.Fish-fed mud crabs had the least energy intake and the least energy for growth,molting,excretion,metabolism,and feces.Among the four treatments,the mud crabs fed on Polychaete had the largest proportion of energy used for growth,while the mud crabs fed on fish had the largest proportion of energy used for molting.The proportion of energy consumed by mud crabs fed on Polychaete was the smallest,which may be the main reason for the higher FCE-P and FCE-E of mud crabs fed on Polychaete.[Conclusions]The results of this experiment showed that the utilization of low-value fish by mud crabs was the worst,suggesting that fish should not be used as control or reference food when studying the formula feed of mud crabs.

The Science of Radio Astronomy: An Investigation of Crab Nebula

The science of radio astronomy focuses on the observation and study of celestial objects by reading their radio waves. The 5 meter radio-telescope is able to observe different radio sources using a C-band LNB. This research was essentially focused on Crab Nebula, also known as Taurus A. The study led to interesting observations, which were validated numerically using various scientific computing software. The radio waves emitted by Taurus A are readable by the RTL-SDR, a software defined radio receiver. This device is capable of reading radio frequencies in the range of 0.5 MHZ to 1700 MHZ.

Crab脉冲星X射线计时观测数据处理与分析

对我国公开发布的空间试验卫星X射线探测器观测Crab脉冲星的数据进行了处理与分析,描述了利用X射线脉冲星观测数据与卫星轨道数据建立积分脉冲轮廓与标准脉冲轮廓的方法,给出了在频域测量脉冲星脉冲到达时刻(toa)的原理方法与算法.利用每组观测数据,计算得到Crab脉冲星脉冲toa,通过与Crab脉冲星星历预报脉冲toa的比较,分析得到卫星载荷X射线探测器观测Crab脉冲星,在消除掉系统误差后,50 min积分时间的观测精度约14μs.

拟南芥心皮发育CRABS CLAW基因的克隆与荠菜遗传转化

CRABS CLAW(CRC)是控制拟南芥心皮发育的主要基因之一,属MADS box基因家族中的成员.根据GenBank收录的CRABS CLAW基因的cDNA序列设计引物,通过RT-PCR的方法,从哥伦比亚型拟南芥总RNA中扩增出CRABS CLAW基因的全长cDNA片段,将其克隆到pMD18-T载体中,经测序证明该片段与GenBank报道的序列完全一致.以Ti质粒载体pWM101为基础,构建了由组成型启动子CaMV35S调控的CRC基因的植物表达载体pWM101-CRC,通过根癌农杆菌花序浸渍法转化荠菜,获得了转CRC基因的荠菜植株.CRC基因在荠菜中的组成型表达对荠菜心皮形态和大小都产生了一定影响.

甘蓝型油菜CRABS CLAW基因克隆及其RNA干扰载体的构建

CRABS CLAW(CRC)转录因子是YABBY基因家族成员,在植物花器官发育过程中起重要作用。为进一步研究CRC转录因子在调控油菜花器官发育过程中的作用,本研究以甘蓝型油菜品种宁油10号花蕾RNA为材料,通过反转录PCR克隆到1个580 bp长度的CRC基因,并利用p Hurricane中间载体构建CRC基因的反向重复序列表达框,将CRC基因片段以正向的方式连接在1个可剪切的内含子的5'末端,以反向的方式连接到该内含子的3'末端;然后将Ca MV35S启动子序列和CRC基因的反向重复表达框再克隆到植物双元载体p CAMBIAI1390的p UC18多克隆位点,构建了干扰表达载体p A6-CRCi,经过酶切鉴定和测序分析,所构建的载体正确。

用ASM/RXTE数据对Crab天区的直接解调成像

利用对象重建的直接解调技术，对ＡＳＭ／ＲＸＴＥ的模拟数据和Ｃｒａｂ天区观测数据进行了成像分析．结果表明，借助于对象重建的直接解调技术，可以利用正在运行的Ｘ射线天文卫星ＲＸＴＥ上的全天监测器ＡＳＭ实现硬Ｘ射线天空的成像．

Effects of Heavy Metal and Pollutants on the Non-special Immunity of the Shrimp and Crab

This paper attempted to review and evaluate existing information about the effects of heavy metal, ammonia-N, nitrite and the organic pollutants on the non-special immune response of the shrimp and crab, which providing theory for improving the self-immunity of shrimp and crab by meliorating cultural environment. In addition, it could provide information for further study on this field.

类Crab脉冲星的三维磁层外隙模型

利用三维脉冲星磁展模型研究了磁层外隙的几何结构．首先用自洽模型确定“外隙”的垂直尺度，在该模型中外隙尺度受回流的外隙流（带有隙加速的带电粒子发射的曲率光子）加热极帽而产生的热光子的碰撞而成对生成所限．外隙的横向尺度也受本地对生成所限．在脉冲星的磁层中，原则上有两个拓扑分离的外隙，允许同时进入和流出粒子．不过，流入粒子流产生的辐射形态受隙中本地对生成和恒星附近的磁对生成的严格的制约．根据外隙及其本地结构的三维模型计算了类Ｃｒａｂ脉冲星的辐射形态和相位分解谱．

Changes during late-stage embryonic development from egg-juvenile to free-living hatchling in Chinese freshwater crab Sinopotamon yangtsekiense (Decapoda, Brachyura, Potamidae)

This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.

Crab脉脉冲星巨脉冲研究进展

巨脉冲是一种持续时间很短的射电爆发现象,它们的流量密度往往比平均脉冲大几十倍、百倍,甚至千倍以上,成为脉冲星射电辐射中最显著、最突出的现象。Crab脉冲星自发现以来一直受到广泛关注,它是极少数能够发射巨脉冲的脉冲星之一。射电巨脉冲轮廓形状、微细结构、能量分布的充分研究,对揭示脉冲星辐射机制和具体辐射过程有重要意义。

水溶氧对三疣梭子蟹(crab Portunus trituberculatus,Miers,1876)生理应答的影响(英文)

本研究旨在探究不同水溶氧水平对三疣梭子蟹生理应答的影响。将50只成体三疣梭子蟹（CrabPortunus trituberculatus）分别饲养在不同水溶氧水平（1、2、4、8、12 mg/L）的密封水槽中,10 d后测定其耗氧率,同时比较血液中蛋白质、氧合血蓝蛋白、血细胞含量;测定消化腺代谢产物（糖原、蛋白质、葡萄糖、胆固醇、酰基甘油、乳酸）含量;比较消化酶活性及乳酸脱氢酶活性的差异。结果显示：三疣梭子蟹生存关键的溶氧水平为2~4 mg/L;血液中蛋白质和氧合血蓝蛋白含量与耗氧率一致;消化腺代谢产物糖原和蛋白质含量不随溶氧水平的变化而变化（P〉0.05）,但葡萄糖、胆固醇和酰基甘油含量随溶氧水平降低而呈直线下降;水溶氧对消化酶活性影响不大（P〉0.05）,但乳酸脱氢酶活性和乳酸含量却随溶氧水平降低而显著增加（P〈0.05）;较低的水溶氧还通过明显降低血细胞含量（P〈0.05）来影响三疣梭子蟹的免疫功能。研究表明：三疣梭子蟹可通过改变血液中氧合血蓝蛋白含量、某些消化腺代谢产物含量以及厌氧呼吸等生理机制来适应较低的水溶氧生态环境。

Microsatellite analysis of genetic diversity and population structure of Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crab （Eriocheir sinensis） has higher commercial value as food source than any other species of Eriocheir in China. To evaluate the germplasm resources and characterize the genetic diversity and population structure of the crabs in different water systems, two stocks and two farming populations were assessed with 25 polymorphic microsallite loci available in public GenBank. Basic statistics showed that the average observed heterozygosity （Ho） amongst populations ranged from 0.5789 to 0.6824. However, a remarkable presence of inbreeding and heterozygote deficiencies were observed. To analyze population structure, pairwise FST coefficients explained only -10.3% variability from the subdivision of mitten crab populations, the remaining variability stems from the subdivision within subpopulations. Although the four populations had slight differentiation, different allelic frequencies resulted in distinct population structures. Two stocks and one farming population were clustered together to the phylogenetic branch of Yangtze crab, with an approximate membership of 95%. Whereas, another farming population was clustered singly to the phylogenetic branch of the Liaohe crab, with a membership of 97.1%. The tests for individual admixture showed that Yangtze crab had probably been contaminated with individuals from other water systems. Genetic relationships between populations also supported the conclusion that Yangtze crab and Liaohe crab had different gene pools in spite of the origins of the same species.

Water quality, nutrient budget, and pollutant loads in Chinese mitten crab (Eriocheir sinensis) farms around East Taihu Lake

To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.

Seasonal movements of American horseshoe crabs Limulus polyphemus in the Great Bay Estuary,New Hampshire (USA)

The goal of this study was to determine the year round movement patterns of American horseshoe crabs, Limulus polyphemus, in the Great Bay Estuary, New Hampshire （USA） by using acoustic telemetry to track the movements of 37 adult Limulus, for periods ranging from 2 to 31 months. During the winter （December-March） horseshoe crabs moved very little. In the spring, when water temperatures exceeded II^C, horseshoe crabs moved at least 1 km further up into the estuary to shallower subtidal areas about a month prior to spawning. The mean distance traveled during spring migrations was 2.6 ＋ 0.5 （n=20） km up the estuary. Mating occurred in May and June and during these months animals spent most of their time in shallow subtidal areas adjacent to mating beaches. In the summer （July-Augnst）, animals moved 1.5 ± 0.5 （n=26） km down the estuary, towards the ocean, and ranged widely, using extensive portions of the estuary. In the fall （September-November） movement was more limited （0.5 ± 0.5 km; n = 24） while animals settled into wintering locations, where they remained until spring. The mean annual linear range for all animals was 4.5 ± 0.3 km （n =35） and the maximum distance traveled by an individual horseshoe crab within one year was 9.2 km. There was no evidence that any of the horseshoe crabs tracked during this study left the estuary

Seasonal movement of the American horseshoe crab Limulus polyphemus in a semi-enclosed bay on Cape Cod,Massachusetts (USA) as determined by acoustic telemetry

American horseshoe crabs Limulus polyphemus were tracked using acoustic telemetry and traditional tagging in a semi-enclosed bay on Cape Cod （Pleasant Bay）, Massachusetts, USA, to determine seasonal movement patterns. Fifty-five actively spawning females were fitted with transmitters in 2008 and 2009 and were tracked using acoustic telemetry from May 2008 through July 2010. Fil^een crabs with transmitters also had archive depth-temperature tags attached. In addition, over 2000 spawning crabs （males and females） were tagged with US Fish and Wildlife CIdSFWS） button tags over the same period. Ninety-one percent of the crabs with transmitters were detected during this study. In the spring, crabs were primarily located in the northern section of the bay near spawning beaches, whereas in the fall crabs moved towards the deeper portions of the bay, and some may have overwIntered in the bay. There was evidence that a majority （58%-71%） of the females with transmitters spawned in two sequential seasons. One archive tag was recovered resulting in a year-long continuous record of depth and tem- perature data that, when integrated with telemetry data, indicated that the crab overwintered in the bay. The live recapture rate of crabs with USFWS button tags was 11%, with all re-sighted crabs except one observed inside Pleasant Bay. Eighty-three percent of recaptures were found within 2.5kin of the tagging location, and 51% were observed at the same beach where they were tagged. This study provides further evidence that horseshoe crabs in Pleasant Bay may be philopatric to this embayment