Scandium-bearing carbonates of the Tarr albitite complex,southeast Sinai

Unusually high Sc-concentrations (30 to 150 ppm) were found in the carbonate minerals (dolomite, breunnerite, calcite) of the Tarr albitite complex. Scandium is probably part of the carbonate crystal structure substituting for (Mg, Fe²⁺). Scandium is considered to have originated from a source of mantle-affinity, thus supporting an earlier suggestion that the Tarr albitite complex is related to an ophiolite at depth.     

Drivers of Change and Sustainability in Linked Social–Ecological Systems: An Analysis in the Volta River Basin of Ghana,West Africa

Understanding the nature and relative importance of various drivers of change is crucial for sustainable management of natural resources and in prioritizing management efforts, allocating limited resources, and understanding cumulative effects. For this article, we employed structured an expert judgments approach to identify, characterize, and assess the relative importance of the key biophysical and socioeconomic drivers of change within the Volta River Basin, West Africa. Precipitation variability, water availability, land use change, drought events, and population growth were perceived as most important, while biodiversity loss, social conflicts, pest and disease occurrence, urbanization, and pollution were viewed as less critical. A majority of these drivers were characterized as “slow” acting processes as compared to rapidly changing drivers. Intra- and interexpert groups agreement were found to be significant and convergent, indicating the reliability of the results. The implications of these results for sustainable water resources management and agricultural production are discussed.     

Are Australia’s suburbs swamped by Asians and Muslims? Countering political claims with data

Recent decades have seen substantial growth across many developed-world countries of right-wing populist political parties whose policies oppose immigration and multiculturalism as threats to the majority way of life there. These are exemplified in Australia by Pauline Hanson’s One Nation Party, which was successful at elections there at the turn of the twenty-first century and again in 2016. Part of this party’s rhetoric focuses on the geography of immigrant groups in Australia’s cities, with claims that their members live in ghettos. Is that factually correct? Using data from the 2011 Australian census this paper analyses the distribution of Asians and Muslims (the two groups picked out by One Nation and its leader) at four spatial scales within the country’s 11 largest urban areas. It finds no evidence at all of intensive residential segregation of Muslims, and although there are concentrations of Asians—notably in Sydney and Melbourne—most residents claiming Asian ancestry live in neighbourhoods and suburbs where they form a minority (in many cases a small minority) only of the local population.     

Regional Differences in Affluent Black and Affluent White Residential Outcomes

This study compares the residential outcomes of affluent black and affluent white households using data from the 1990 and 2000 censuses and pooled data from the 2005–2009 American Community Survey. Results indicate that affluent black households are highly segregated from their white economic peers. Furthermore, affluent black households live in neighborhoods of lower average quality compared to affluent white households. Affluent black households are least segregated from affluent white households in the South, but the greatest equality in neighborhood‐quality outcomes occurs in the West. The South, however, shows the greatest improvement in both average neighborhood quality for affluent black households and a substantial reduction in affluent black–affluent white segregation over the entire study period. The authors find that place stratification theory better describes the residential geography of affluent black households than does spatial assimilation theory.     

川滇菱形块体顺时针转动的构造学与古地磁学证据

川滇菱形块体内部受NE向丽江 -小金河断裂的切割 ,可进一步划分为川西北次级块体和滇中次级块体等南北 2个部分 ;各次级块体东边界断裂有规律地左旋滑动、西边界断裂的右旋滑动及其滑动速率值的差异 ,反映出新生代时期各次级块体作向SE的水平滑移叠加绕垂直轴顺时针转动的复合运动。其中 ,川西北次级块体SE向的水平滑移速率 5mm/a ,顺时针转动角速度 1 4°/Ma ;滇中次级块体SE向的水平滑移速率 3 5mm/a ,顺时针转动角速度约 1 5°/Ma。在滇中次级块体内部姚安、大姚、永仁、昆明北马街等地采集到约 90个古新世地层的定向样品 ,通过交变退磁和热退磁获得了它们各自的剩磁矢量 (实验磁偏角和磁倾角 ) ,由实测磁偏角与期望磁偏角相比可知川滇地区滇中次级块体中新世早期以来的顺时针转动累积量可达 30°～ 4 8°。次级块体的整体转动与块边活动断裂的左旋滑动符合左旋走滑断裂作用区块体作顺时针转动的运动学模式     

Radar Detection of Near-Earth Asteroids 2062 Aten, 2101 Adonis, 3103 Eger, 4544 Xanthus, and 1992 QN

We describe Doppler-only radar observations of near-Earth asteroids 2062 Aten, 2101 Adonis, 3103 Eger, 4544 Xanthus, and 1992 QN that were obtained at Arecibo and Goldstone between 1984 and 1996. Estimates of the echo spectral bandwidths, radar cross sections, and circular polarization ratios of these objects constrain their pole-on breadths, radar albedos, surface roughnesses, taxonomic classes, rotation periods, and pole directions. Aten's bandwidth is consistent with its radiometrically determined diameter of 0.9 km. Adonis has a rotation periodP≤ 11 h and an effective diameter (the diameter of a sphere with the same projected area as the asteroid) between 0.3 and 0.8 km. The radar properties of Adonis suggest it is not a member of taxonomic classes C or M. The effective diameter of Xanthus is between 0.4 and 2.2 km with a rotation periodP≤ 20 h. Echoes from 1992 QN constrain the asteroid's pole-on breadth to be ≥0.6 km and probably exclude it from the C and M taxonomic classes. The strongest Eger echoes are asymmetric with bandwidths that set lower bounds of 1.5 and 2.3 km on the minimum and maximum breadths of the asteroid's pole-on silhouette. If Eger is modeled as a 1.5 × 2.3 km biaxial ellipsoid, then its effective diameter for an equatorial view is 1.5 km end-on and 1.9 km broadside or pole-on, implying a geometric albedo smaller than published values but still consistent with a classification as an E-type object. The near-unity circular polarization ratios of Adonis, Eger, and 1992 QN are among the highest values measured for any asteroid or comet and suggest extreme near-surface roughness at centimeter to meter scales.     

Redundancy resolution for underwater mobile manipulators

A new fault-tolerant redundancy resolution scheme is presented that allows a single six degree of freedom (DOF) command to be distributed over a small remotely operated underwater vehicle–manipulator (ROVM) system. ROVM systems are composed of a remotely operated underwater vehicle (ROV) and serial manipulator. The combined system is often kinematically redundant for the six-DOF end-effector command, and such a ROVM system admits an infinite number of joint-space solutions for a commanded end-effector state. In the current work, the primary objective is to follow the desired end-effector velocities commanded by a human pilot. The primary objective is realized using the right Moore–Penrose pseudoinverse solution that minimizes the two-norm of the collective joint velocities. Secondary objectives considered are: avoiding manipulator joint limits, avoiding singularities and high joint velocities, keeping the end-effector in sight of the on-board camera, minimizing the ROV motion, and minimizing the drag-forces on the ROV. Each criterion is defined within the framework of the gradient projection method (GPM). The hierarchy for the secondary tasks is established by a low-level artificial pilot that determines a weighting factor for each criterion based on if–then-type fuzzy rules that reflect an expert human pilot's knowledge. The resulting weight schedule yields a self-motion (null-space motion) that emulates how a skilled operator would utilize the redundancy of the ROVM to achieve the secondary objectives. In addition, the proposed method has a fault-tolerant property that enforces joint-velocity limits and also redistributes the end-effector velocity command in the case of faulty joints. To demonstrate the efficacy of the proposed scheme, a numerical simulation case study is performed. The results illustrate that complex spatial end-effector manoeuvres that are otherwise not possible with a stationary ROV can be accomplished in real-time via the coordination of the ROV and the manipulator. The on-line nature of the proposed scheme makes it suitable for remote systems where the desired end-effector state is not known a priori.