Line emission from accretion discs around black holes: the analytic approach

The broad X-ray iron line observed in many active galactic nuclei spectra is thought to originate from the accretion disc surrounding the putative supermassive black hole. We show here how to perform the analytical integration of the geodesic equations that describe the photon trajectories in the general case of a rotating black hole (Kerr metric), in order to write a fast and efficient numerical code for modelling emission line profiles from accretion discs.     

Dynamics of the Jupiter Trojans with Saturn’s perturbation when the two planets are in migration

In a previous paper (Hou et al. in Celest Mech Dyn Astron 119:119–142, 2014a), the problem of dynamical symmetry between two Jupiter triangular libration points (TLPs) with Saturn’s perturbation in the present configuration of the two planets was studied. A small short-time scale spatial asymmetry exists but gradually disappears with the time going, so the planar stable regions around the two Jupiter TLPs should be dynamically symmetric from a longtime perspective. In this paper, the symmetry problem is studied when the two planets are in migration. Several mechanisms that can cause asymmetries are discussed. Studies show that three important ones are the large short-time scale spatial asymmetry when Jupiter and Saturn are in resonance, the changing orbits of Jupiter and Saturn in the planet migration process, and the chaotic nature of Trojan orbits during the planet migration process. Their joint effects can cause an observable difference to the two Jupiter Trojan swarms. The thermal Yarkovsky effect is also found to be able to cause dynamical differences to the two TLPs, but generally they are too small to be practically observed.     

SAINF: A toolbox for analyzing the effect of point-like,line-like and polygon-like infrastructural features on the distribution of point-like non-infrastructural features

This paper introduces a GIS-based toolbox, called SAINF, for analyzing the effects of infrastructural features on the distribution of non-infrastructural features. One of the distinct characteristics of SAINF is that it can deal not only with point-like infrastructural features but also line-like (e.g. railways) and polygon-like (e.g. big parks) features. SAINF analyzes these effects with the conditional nearest neighbor distance method and the cross K-function method. First, the paper briefly refers to these methods. Second, the paper illustrates how to use SAINF with an actual example. SAINF can be downloaded via the Internet without charge for non-profit uses.We express our thanks to Exceed Co. Ltd. for helping us program SAINF, and to Miki Arimoto for making the data of high-class apartment buildings and parks in Kiba. This development was partly supported by Grant-in-aid for Scientific Research No. 10202201 (Spatial information science for human and social sciences) and No. 14350327 (Regional supporting network planning for the elderly) by the Ministry of Education, Culture, Sports, Science and Technology of Japan.     

The Role of Education in the National Tsunami Hazard Mitigation Program

Tsunami education activities, materials, and programs are recognized by the National Tsunami Hazard Mitigation Program (NTHMP) as the essential tool for near-source tsunami mitigation. Prior to the NTHMP, there were no state tsunami education programs outside of Hawaii and few earthquake education materials included tsunami hazards. In the first year of the NTHMP, a Strategic Plan was developed providing the framework for mitigation projects in the program. The Strategic Plan identifies education as the first of five mitigation strategic planning areas and targets a number of user groups, including schools, businesses, tourists, seasonal workers, planners, government officials, and the general public. In the 6 years of the NTHMP tsunami education programs have been developed in all five Pacific States and include print, electronic and video/film products, curriculum, signage, fairs and workshops, and public service announcements. Multi-state education projects supported by the NTHMP include TsuInfo, a bi-monthly newsletter, and Surviving a Tsunami, a booklet illustrating lessons from the 1960 Chilean tsunami. An additional education component is provided by the Public Affairs Working Group (PAWG) that promotes media coverage of tsunamis and the NTHMP. Assessment surveys conducted in Oregon, Washington, and Northern California show an increase in tsunami awareness and recognition of tsunami hazards among the general population since the NTHMP inception.     

对流移入杭州湾后飑线发展机制分析

利用多源观测资料,对2021年4月30日发生在黄淮地区的一次强对流过程中由不同类型风暴系统造成的极端对流大风进行了探讨。研究表明,此次强对流过程发生在东北冷涡背景下的强风垂直切变和层结不稳定环境中,地面气旋及锋面触发了初始对流,在之后近10 h的传播过程中经历了组织化发展、孤立风暴新生、发展、合并与重组等不同阶段。期间,由两种不同类型风暴产生了特征相异的对流性大风：第一阶段,以江苏淮安站为代表,苏中极端对流性大风（36.2 m/s）是由发展强烈的超级单体风暴引发下击暴流所致。对流风暴低层呈现出明显的钩状回波特征,对应深厚的具有显著气旋性旋转的中气旋,在地面极端大风临近时刻,中气旋存在同时向上和向下拉伸、水平尺度快速收缩过程。贯穿整个风暴的下沉气流位于风暴钩状回波后侧,这支强下沉气流至地面附近迅速向外辐散,伴随风暴内强反射率核快速下降,导致淮安产生时、空尺度小且空间分布显著不连续的极端大风。第二阶段,以江苏南通地区为代表,苏东南地区极端大风的发展过程涉及多尺度天气系统的相互作用。线状对流系统前部存在明显的阵风锋,造成较大范围10级以上的地面大风;南通通州湾极端大风（47.9 m/s）发生在阵风锋后侧,其形成一方面是由于线形对流风暴造成的强冷池与地面冷锋相叠加,形成更强的气压梯度,另一方面与地面中尺度气旋入海过程中的快速发展以及风暴后侧倾斜向前的下沉气流导致的高空风动量下传有关。     

Swiss and Alpine geologists between two tectonic revolutions. Part 2: From drifting continents towards plate tectonics

Following the major contributions of Wegener and Argand (Part 1), it was the work of synthesis carried out by R. Staub that represented the major contribution Alpine geology made with respect to that heritage. The research work of young scientists (Gagnebin, Juvet, Wavre, Leuba) who had been influenced by Argand was of lesser importance. Ampferer’s ground breaking contribution, coming along with illuminating graphic illustrations, was all but ignored. Although remaining fairly popular, the theory of continental drift found itself under the heavy fire of criticism from influential geologists in the USA and in Europe. In order to test the validity of the idea, C.E. Wegmann suggested linking geological field work with oceanographic research. He showed that the trajectories of drifting had to be conceived as following the small circles of the sphere. With regard to Alpine geologists of the time, they were renowned for the high quality of their geological mapping. This remained the very special activity in which they excelled, but they focused on topics that were becoming narrower and narrower, and increasingly specialised. The new avenues for research that Holmes and Hess opened up had but little impact on Alpine geologists. In fact, they apparently remained unaware of a note by Holmes written in German and published in a Swiss journal. On the eve of the Second World War, the meeting of the Geologische Vereinigung devoted to the origin of the Atlantic Ocean confirmed that continental drift was being seriously challenged, although a few papers pointed to new developments, e.g. that in Iceland extensional tectonics had been active for the last 5,000 years. Most Alpine geologists were either highly critical of the theory of plate tectonic when it arrived or expressed serious reservations towards the idea. Of the exceptions, first Laubscher and then Bernoulli showed very clearly how important the new theory could be for understanding the evolution of Alpine orogeny. Continental drift and plate tectonics were very much the product of the creative imagination of human minds. Whereas Wegener used a broad range of confirmed results, plate tectonics sprang out of the new research being carried out in the domain of oceans. Graphic illustration was one of the favourite vehicles used to put across these new perspectives. Sometimes their impact remained alive long after their author had withdrawn his backing for the idea (as was the case for Argand’s “embryonic tectonics”); sometimes, even in spite of their very high standard, they were just ignored (which was the case for Ampferer).     

Trace elements in medium-temperature (40–80 °C) thermal waters from the Mura basin (North-Eastern Slovenia)

Medium-temperature thermal waters in the Mura basin occur in hydrogeological systems different in age, burial depth, temperature, porosity and permeability, and the presence of free carbon dioxide which penetrates through the fractures from pre-Tertiary basement. The waters commonly belong to sodium-bicarbonate hydrogeochemical facies, but may have significantly different amounts of total dissolved solids, including trace elements. Thermal waters occurring in low-permeable, well-compacted and moderately fractured Tertiary sediments older than Upper Pliocene are the richest in trace elements, although their abundance may be very variable from one aquifer to another. The ratios of major alkaline and alkaline earth elements (Na, K, Ca) and trace elements (Li, Rb, Cs, Ba, Sr) commonly show relative enrichment in highly mineralised waters with respect to the waters with lower mineralisation. Rare earth elements (REEs) and Y show only minor fractionation in the highly mineralised waters, whereas in the waters with lower mineralisation strong fractionation of heavy rare earth elements (HREEs) over light rare earth elements (LREEs) occurs, along with a pronounced positive europium anomaly. Positive Th/U ratios are commonly observed, although both actinide elements occur in the range of some hundredths of ppb to some ppb. Trace elements were particularly useful in the study of well cycling in two hydraulically interconnected geothermal wells in the town of Murska Sobota, which produce a mixture of low- and high-mineralised waters.     

The Spectrum and Dips of RE 0751+14: A Joint Evaluation of ROSAT and ASCA Archival Data

Using archival ASCA and ROSAT observations of RE 0751+14, X- ray energy spectra, pulse profiles and the results of pulse timing analysis are presented. The energy spectra are well-fitted by a blackbody model at low energy and a Raymond-Smith model at high energy, together with a partial covering absorber. A fluorescence emission line at 6.4 keV with an equivalent width ∼ 220 eV was resolved for the first time. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evolution of Solar and Geomagnetic Activity Indices, and Their Relationship: 1960?�C?2001

We employ annually averaged solar and geomagnetic activity indices for the period 1960??C?2001 to analyze the relationship between different measures of solar activity as well as the relationship between solar activity and various aspects of geomagnetic activity. In particular, to quantify the solar activity we use the sunspot number R _s, group sunspot number R _g, cumulative sunspot area Cum, solar radio flux F10.7, and interplanetary magnetic field strength IMF. For the geomagnetic activity we employ global indices Ap, Dst and Dcx, as well as the regional geomagnetic index RES, specifically estimated for the European region. In the paper we present the relative evolution of these indices and quantify the correlations between them. Variations have been found in: i) time lag between the solar and geomagnetic indices; ii) relative amplitude of the geomagnetic and solar activity peaks; iii) dual-peak distribution in some of solar and geomagnetic indices. The behavior of geomagnetic indices is correlated the best with IMF variations. Interestingly, among geomagnetic indices, RES shows the highest degree of correlation with solar indices.     

GETEMME—a mission to explore the Martian satellites and the fundamentals of solar system physics

GETEMME (Gravity, Einstein??s Theory, and Exploration of the Martian Moons?? Environment), a mission which is being proposed in ESA??s Cosmic Vision program, shall be launched for Mars on a Soyuz Fregat in 2020. The spacecraft will initially rendezvous with Phobos and Deimos in order to carry out a comprehensive mapping and characterization of the two satellites and to deploy passive Laser retro-reflectors on their surfaces. In the second stage of the mission, the spacecraft will be transferred into a lower 1500-km Mars orbit, to carry out routine Laser range measurements to the reflectors on Phobos and Deimos. Also, asynchronous two-way Laser ranging measurements between the spacecraft and stations of the ILRS (International Laser Ranging Service) on Earth are foreseen. An onboard accelerometer will ensure a high accuracy for the spacecraft orbit determination. The inversion of all range and accelerometer data will allow us to determine or improve dramatically on a host of dynamic parameters of the Martian satellite system. From the complex motion and rotation of Phobos and Deimos we will obtain clues on internal structures and the origins of the satellites. Also, crucial data on the time-varying gravity field of Mars related to climate variation and internal structure will be obtained. Ranging measurements will also be essential to improve on several parameters in fundamental physics, such as the Post-Newtonian parameter ?? as well as time-rate changes of the gravitational constant and the Lense-Thirring effect. Measurements by GETEMME will firmly embed Mars and its satellites into the Solar System reference frame.