Editorial: Categorising Migrants: Standards, complexities, and politics

In spring 2017, New York Times correspondent Patrick Kingsley went to Turkey to cover the lives of Syrian refugees. In Istanbul, Kingsley met Abu Mohammed, a former surgeon’s assistant from Syria, who between 2015 and 2016 had helped to facilitate the passage of refugees from his home country into Greece. After narrowly escaping death in his own failed attempt to reach Europe, Mohammed had earned some USD 800,000 with ‘smuggling’ activities. He himself spoke of a ‘dirty business’, but it had also been more than just a business—the refugees whom he had helped reach Europe included relatives and even his own son. Kingsley also met 15-year-old Syrian Ismail Alanzi, a refugee working ‘up to 11 hours a day, six days a week’ on a farm in the east of Turkey—much more than the limit set by Turkish law for someone his age. With his father unable to find employment, however, the burden of supporting the family fell upon Ismail. He earned about TRY 800 (USD 225) per month for his toil, which was little more than half of the statutory minimum wage in the country. Ismail also received permission for his family to set up a tent on the land of his employer as they struggled to find proper housing. Turkish law restricts refugees to residing in the province where they are registered, but the family had moved in search of work

Structural and Functional Connectivity as a Driver of Hillslope Erosion Following Disturbance

Hydrologic response to rainfall on fragmented or burnt hillslopes is strongly influenced by the ensuing connectivity of runoff and erosion processes. Yet cross-scale process connectivity is seldom evaluated in field studies owing to scale limitations in experimental design. This study quantified surface susceptibility and hydrologic response across point to hillslope scales at two degraded unburnt and burnt woodland sites using rainfall simulation and hydrologic modelling. High runoff (31–47 mm) and erosion (154–1893 g m–2) measured at the patch scale (13 m2) were associated with accumulation of fine-scale (0.5-m2) splash-sheet runoff and sediment and concentrated flow formation through contiguous bare zones (64–85% bare ground). Burning increased the continuity of runoff and sediment availability and yield. Cumulative runoff was consistent across plot scales whereas erosion increased with increasing plot area due to enhanced sediment detachment and transport. Modelled hillslope-scale runoff and erosion reflected measured patch-scale trends and the connectivity of processes and sediment availability. The cross-scale experiments and model predictions indicate the magnitude of hillslope response is governed by rainfall input and connectivity of surface susceptibility, sediment availability, and runoff and erosion processes. The results demonstrate the importance in considering cross-scale structural and functional connectivity when forecasting hydrologic and erosion responses to disturbances

Time-Resolved Measurement of Interatomic Coulombic Decay in Ne_2

The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne_2 is determined via an extreme ultraviolet pump-probe experiment at the Free-Electron Laser in Hamburg. The pump pulse creates a 2s inner-shell vacancy in one of the two Ne atoms, whereupon the ionized dimer undergoes ICD resulting in a repulsive Ne^{+}(2p^{-1}) - Ne^{+}(2p^{-1}) state, which is probed with a second pulse, removing a further electron. The yield of coincident Ne^{+} - Ne^{2+} pairs is recorded as a function of the pump-probe delay, allowing us to deduce the ICD lifetime of the Ne_{2}^{+}(2s^{-1}) state to be (150 +/- 50) fs in agreement with quantum calculations.Comment: 5 pages, 3 figures, accepted by PRL on July 11th, 201

Reliable 4.8 T trapped magnetic fields in Gd-Ba-Cu-O bulk superconductors using pulsed field magnetization

Abstract A robust and reliable in-situ magnetization method is essential for exploiting the outstanding magnetic flux trapping ability of bulk superconductors in practical applications. We report a 4.8 T peak trapped magnetic field, B T, achieved at 30 K in a 36 mm diameter GdBa2Cu3O7-δ –Ag bulk superconductor using pulsed field magnetization (PFM). To realize this, we have developed a reliable two-step multi-pulse PFM process based on understanding and exploiting the avalanche-like flux jump phenomenon observed in these materials. The magnitude of the applied pulsed magnetic field (B a) necessary to trap 4.8 T was merely 5.29 T, corresponding to a remarkable magnetization efficiency (B T/B a) of 90%.This study was supported by the Engineering and Physical Sciences Research Council (No. EP/P00962X/1), the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB25000000), the National Key R&D Program (2016YFF0101701) and the project (6140923050202). M D Ainslie would like to acknowledge financial support from an Engineering and Physical Sciences Research Council (EPSRC) Early Career Fellowship, EP/P020313/

High‐temperature ternary oxide phases in Ta/Nb‐Alumina composite materials

Coarse-grained composites of refractory ceramics and refractory metals are a novel approach for materials at application temperatures up to 1500 °C. Al$_{2}$O$_{3}$ and the refractory metals Nb and Ta are suitable candidates for enhanced thermal shock capability, as they show similar thermal expansion. During fabrication, a key aspect to consider is the possible formation of additional phases upon interaction of the constituent phases as well as through reaction with the environment. X-Ray diffraction (XRD) and investigations of the microstructure with scanning electron microscopy methods unveil Al$_{2}$O$_{3}$–Nb composite to form NbO, whereas for Al$_{2}$O$_{3}$–Ta the ternary compound aluminum tantalate (AlTaO$_{4}$) is found. Thermodynamic calculations show that the changing oxygen solubility in Nb accounts for the formation of NbO, and explain the absence of a corresponding niobate (AlNbO4) phase. AlTaO$_{4}$ is identified as the disordered tetragonal high-temperature modification

High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules

Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 10$^{11}$ photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH$_3$I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafast molecular dynamics with table-top XUV-photon sources. These table-top sources can provide significantly higher repetition rates than the currently operating free-electron lasers and they offer very high temporal resolution due to the intrinsically small timing jitter between pump and probe pulses

Developing a Parameterization Approach for Soil Erodibility for the Rangeland Hydrology and Erosion Model (RHEM)

Soil erodibility is a key factor for estimating soil erosion using physically based models. In this study, a new parameterization approach for estimating erodibility was developed for the Rangeland Hydrology and Erosion Model (RHEM). The approach uses empirical equations that were developed by applying piecewise regression analysis to predict the differences of erodibility before and after disturbance (i.e., wildfire, prescribed fire, and tree encroachment) and across a wide range of soil textures as a function of vegetation cover and surface slope angle. The approach combines rain splash, sheet flow, and concentrated flow erodibilities into a single parameter for modeling erodibility in most cases. We evaluated the new approach for sites representing different degrees of disturbance associated with burning and tree encroachment. Our results show that the new erodibility approach in RHEM predicts erosion at the plot scale with a satisfactory range of error in all cases. The new approach extends the applications of RHEM to a greater scope of landscapes and soil texture

Charge transfer in dissociating iodomethane and fluoromethane molecules ionized by intense femtosecond X-ray pulses

Citation: Boll, R., Erk, B., Coffee, R., Trippel, S., Kierspel, T., Bomme, C., . . . Rudenko, A. (2016). Charge transfer in dissociating iodomethane and fluoromethane molecules ionized by intense femtosecond X-ray pulses. Structural Dynamics, 3(4). doi:10.1063/1.4944344Additional Authors: Marchenko, T.;Miron, C.;Patanen, M.;Osipov, T.;Schorb, S.;Simon, M.;Swiggers, M.;Techert, S.;Ueda, K.;Bostedt, C.;Rolles, D.;Rudenko, A.Ultrafast electron transfer in dissociating iodomethane and fluoromethane molecules was studied at the Linac Coherent Light Source free-electron laser using an ultraviolet-pump, X-ray-probe scheme. The results for both molecules are discussed with respect to the nature of their UV excitation and different chemical properties. Signatures of long-distance intramolecular charge transfer are observed for both species, and a quantitative analysis of its distance dependence in iodomethane is carried out for charge states up to I21+. The reconstructed critical distances for electron transfer are in good agreement with a classical over-the-barrier model and with an earlier experiment employing a near-infrared pump pulse. © 2016 Author(s)