Structure determination of the clean Co(110) surface by LEED

The atomic structure of the (11 0) surface of cobalt has been determined by LEED using six intensity spectra at normal incidence. The surface exhibits the truncated bulk structure with a contraction of the first interlayer spacing by about 8.5% with respect to the bulk value. Quantitative evaluation of the LEED spectra was done using Zanazzi and Jona's and Pendry's r-factors. The minimum averaged r-factors are and . No change of the interatomic distances within the plane could be detected and no rearrangement of the surface structure takes place up to temperatures shortly below the transition temperature

An online programme to reduce depression in patients with multiple sclerosis: a randomised controlled trial

Summary Background With a lifetime risk for major depressive disorder of up to 50%, depression is a common comorbidity in multiple sclerosis but remains widely underdiagnosed and untreated. We investigated the potential of a fully automated, internet-based, cognitive behavioural therapy programme, Deprexis, to reduce depressive symptoms in patients with multiple sclerosis. Methods For this randomised controlled trial, we recruited patients from an outpatient clinic in Hamburg, Germany. Patients aged 18–65 years were eligible for inclusion if they had multiple sclerosis and self-reported depressive symptoms. By use of a computer-generated randomisation sequence, we allocated 90 patients (1:1; no blocking or stratification) to either the intervention group or a waitlist control group for 9 weeks. The primary endpoint was the Beck Depression Inventory (BDI), as assessed by an intention-to-treat analysis. This trial is registered with ClinicalTrials.gov, number NCT01663649. Findings 71 patients completed the trial: 35 patients in the intervention group and 36 patients in the control group. During the intervention, BDI scores decreased in the Deprexis group and increased in the control group, yielding a positive effect of Deprexis relative to the waitlist group (mean group difference –4·02 points [95% CI –7·26 to –0·79], p=0·015, effect size d=0·53). Worsening of depressive symptoms from below to above the clinical cutoff (BDI >13) occurred in three (7%) of 45 patients in the control group and no patients in the Deprexis group. We noted no adverse events with respect to new occurrence of suicidal ideation during the trial. Interpretation Psychological online-intervention programmes could be suitable for patients with multiple sclerosis who are unable to regularly attend therapeutic sessions because of mobility impairments. Funding European Union and the Deutsche Forschungsgemeinschaft

Structure determination of the (1×2) and (1×3) reconstructions of Pt(110) by low-energy electron diffraction

The atomic geometry of the (1×2) and (1×3) structures of the Pt(100) surface has been determined from a low-energy electron-diffraction intensity analysis. Both structures are found to be of the missing-row type, consisting of (111) microfacets, and with similar relaxations in the subsurface layers. In both reconstructions the top-layer spacing is contracted by approximately 20% together with a buckling of about 0.17 Å in the third layer and a small lateral shift of about 0.04 Å in the second layer. Further relaxations down to the fourth layer were detectable. The surface relaxations correspond to a variation of interatomic distances, ranging from -7% to +4%, where in general a contraction of approximately 3% for the distances parallel to the surface occurs. The Pendry and Zanazzi-Jona R factors were used in the analysis, resulting in a minimum value of RP=0.36 and RZJ=0.26 for 12 beams at normal incidence for the (1×2) structure, and similar agreement for 19 beams of the (1×3) structure. The (1×3) structure has been reproducibly obtained after heating the crystal in an oxygen atmosphere of 5×10-6 mbar at 1200 K for about 30 min and could be removed by annealing at 1800 K for 45 min after which the (1×2) structure appeared again. Both reconstructed surfaces are clean within the detection limits of the Auger spectrometer. CO adsorption lifts the reconstruction in both structures. After desorption at 500 K the initial structures appear again, indicating that at least one of the reconstructions does not represent the equilibrium structure of the clean surface and may be stabilized by impurities

Cold-water corals in the Bay of Biscay - occurrences and distribution in space and time (TransBiscay) - Cruise No. M84/5, May 31 - June 21, 2011, Vigo (Spain) - Brest (France)

The scientific objectives of METEOR cruise M84/5 focused on the measurement and analysis of the environmental controls of modern and fossil cold-water coral growth along a transect in the Bay of Biscay. In four working areas we successfully deployed lander systems and CTD/Ro’s to document the physical and hydrochemical characteristics of bottom water masses and the water column in general. These are used to shed light on potential linkages to modern cold-water coral growth and distribution. These investigations were flanked by plankton tows in surface waters. The base for all investigations was a thorough hydroacoustic survey to characterize potential cold-water coral bearing areas with living colonies. Based on these maps we deployed all video-guided gear such as the OFOS-video sled, the TV grab, and the lander systems. Benthic assemblages and sedimentary structures have been documented and sampled with the OFOS and a box corer. Simultaneously, genetic samples of the living coral material were taken for additional studies. Furthermore, we have taken gravity cores to investigate the paleoceanographic conditions as well as the timing of cold-water coral colonization in the Bay of Biscay. Along with the coring efforts, a detailed sampling and study of porewater properties was performed. An additional aim of this cruise was to investigate the influence of boundary exchange processes on the Neodymium isotopy in bottom waters along the pathway of the Mediterranean Outflow water (MOW) by taking multiple samples with the CTD/Ro. The new data and samples of this METEOR cruise will provide the framework to investigate the timing of cold-water coral colonization in the Bay of Biscay, as well as its interplay with the ambient hydrography and geochemistry. This successful cruise has provided the basis to investigate the scientific aims of this expedition in great detail

Direct characterization of photo-induced lattice dynamics in BaFe₂As₂

Ultrafast light pulses can modify electronic properties of quantum materials by perturbing the underlying, intertwined degrees of freedom. In particular, iron-based superconductors exhibit a strong coupling among electronic nematic fluctuations, spins and the lattice, serving as a playground for ultrafast manipulation. Here we use time-resolved X-ray scattering to measure the lattice dynamics of photoexcited BaFe$_{2}$As$_{2}$. On optical excitation, no signature of an ultrafast change of the crystal symmetry is observed, but the lattice oscillates rapidly in time due to the coherent excitation of an A$_{1g}$ mode that modulates the Fe–As–Fe bond angle. We directly quantify the coherent lattice dynamics and show that even a small photoinduced lattice distortion can induce notable changes in the electronic and magnetic properties. Our analysis implies that transient structural modification can be an effective tool for manipulating the electronic properties of multi-orbital systems, where electronic instabilities are sensitive to the orbital character of bands

Long-term geomagnetically induced current observations in New Zealand: Earth return corrections and geomagnetic field driver

Transpower New Zealand Limited has measured DC currents in transformer neutrals in the New Zealand electrical network at multiple South Island locations. Near-continuous archived DC current data exist since 2001, starting with 12 different substations and expanding from 2009 to include 17 substations. From 2001 to 2015 up to 58 individual transformers were simultaneously monitored. Primarily, the measurements were intended to monitor the impact of the high-voltage DC system linking the North and South Islands when it is operating in “Earth return” mode. However, after correcting for Earth return operation, as described here, the New Zealand measurements provide an unusually long and spatially detailed set of geomagnetically induced current (GIC) measurements. We examine the peak GIC magnitudes observed from these observations during two large geomagnetic storms on 6 November 2001 and 2 October 2013. Currents of ~30–50 A are observed, depending on the measurement location. There are large spatial variations in the GIC observations over comparatively small distances, which likely depend upon network layout and ground conductivity. We then go on to examine the GIC in transformers throughout the South Island during more than 151 h of geomagnetic storm conditions. We compare the GIC to the various magnitude and rate of change components of the magnetic field. Our results show that there is a strong correlation between the magnitude of the GIC and the rate of change of the horizontal magnetic field (H′). This correlation is particularly clear for transformers that show large GIC current during magnetic storms

Investigating human audio-visual object perception with a combination of hypothesis-generating and hypothesis-testing fMRI analysis tools

Primate multisensory object perception involves distributed brain regions. To investigate the network character of these regions of the human brain, we applied data-driven group spatial independent component analysis (ICA) to a functional magnetic resonance imaging (fMRI) data set acquired during a passive audio-visual (AV) experiment with common object stimuli. We labeled three group-level independent component (IC) maps as auditory (A), visual (V), and AV, based on their spatial layouts and activation time courses. The overlap between these IC maps served as definition of a distributed network of multisensory candidate regions including superior temporal, ventral occipito-temporal, posterior parietal and prefrontal regions. During an independent second fMRI experiment, we explicitly tested their involvement in AV integration. Activations in nine out of these twelve regions met the max-criterion (A < AV > V) for multisensory integration. Comparison of this approach with a general linear model-based region-of-interest definition revealed its complementary value for multisensory neuroimaging. In conclusion, we estimated functional networks of uni- and multisensory functional connectivity from one dataset and validated their functional roles in an independent dataset. These findings demonstrate the particular value of ICA for multisensory neuroimaging research and using independent datasets to test hypotheses generated from a data-driven analysis

Measurement of event shapes in deep inelastic scattering at HERA

Inclusive event-shape variables have been measured in the current region of the Breit frame for neutral current deep inelastic ep scattering using an integrated luminosity of 45.0 pb^-1 collected with the ZEUS detector at HERA. The variables studied included thrust, jet broadening and invariant jet mass. The kinematic range covered was 10 < Q^2 < 20,480 GeV^2 and 6.10^-4 < x < 0.6, where Q^2 is the virtuality of the exchanged boson and x is the Bjorken variable. The Q dependence of the shape variables has been used in conjunction with NLO perturbative calculations and the Dokshitzer-Webber non-perturbative corrections (`power corrections') to investigate the validity of this approach.Comment: 7+25 pages, 6 figure