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Copper resistance is a key virulence trait of the uropathogen Proteus mirabilis. Here we show that P. mirabilis ScsC (PmScsC) contributes to this defence mechanism by enabling swarming in the presence of copper. We also demonstrate that PmScsC is a thioredoxin-like disulfide isomerase but, unlike other characterized proteins in this family, it is trimeric. PmScsC trimerization and its active site cysteine are required for wild-type swarming activity in the presence of copper. Moreover, PmScsC exhibits unprecedented motion as a consequence of a shape-shifting motif linking the catalytic and trimerization domains. The linker accesses strand, loop and helical conformations enabling the sampling of an enormous folding landscape by the catalytic domains. Mutation of the shape-shifting motif abolishes disulfide isomerase activity, as does removal of the trimerization domain, showing that both features are essential to foldase function. More broadly, the shape-shifter peptide has the potential for 'plug and play' application in protein engineering.

A quantum critical point (QCP) is currently being conjectured for the BaFe$_2$(As$_{1-x}$P$_x$)$_2$ system at the critical value $x_{\rm c} \approx$ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such an universal behavior has not, however, been found in the superconducting upper critical field $H_{\rm c2}$. Here we report $H_{\rm c2}$-data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multi-band analysis we find that $H_{\rm c2}$ is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the doping-induced QCP that is essentially band-dependent. Our results point to two qualitatively different groups of electrons in BaFe$_2$(As$_{1-x}$P$_x$)$_2$. The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems., 9 pages, 3 figures, and Supplementary materials

In this work we present multilayers consisting of Fe and Co-doped BaFe 2 As 2 fabricated by UHV pulsed laser deposition. Employing the advantage of a coherent interfacial bonding between the FeAs tetrahedra of the iron pnictide and bcc Fe enables the growth of epitaxial bi- and multilayers of Fe and the new Fe-based superconductors with high crystalline quality. Epitaxial growth of the multilayers was controlled in situ by reflection high energy electron diffraction (RHEED) and after film growth by X-ray diffraction and TEM analysis. The stoichiometry determined by Auger electron spectroscopy (AES) indicated As-deficient layers of Co-doped Ba-122. The multilayers exhibit critical temperatures of T c,90 = 29 K which is so far the highest critical temperature reported for Co-doped Ba-122. We propose that the T c -enhancement is caused by As-vacancies.

We report on electrical transport properties of epitaxial Ba(Fe1-xNix)2As2 thin films grown by pulsed laser deposition in static magnetic fields up to 35 T. The thin film shows a critical temperature of 17.2 K and a critical current density of 5.7x10^5 A/cm^2 in self field at 4.2 K while the pinning is dominated by elastic pinning at two-dimensional nonmagnetic defects. Compared to single-crystal data, we find a higher slope of the upper critical field for the thin film at a similar doping level and a small anisotropy. Also an unusual small vortex liquid phase was observed at low temperatures, which is a striking difference to Co-doped BaFe2As2 thin films., Comment: Accepted for publication in Applied Physics Letters, 5 figures

The Hall effect is a powerful tool for investigating carrier type and density. For single-band materials, the Hall coefficient is traditionally expressed simply by $R_H^{-1} = -en$, where $e$ is the charge of the carrier, and $n$ is the concentration. However, it is well known that in the critical region near a quantum phase transition, as it was demonstrated for cuprates and heavy fermions, the Hall coefficient exhibits strong temperature and doping dependencies, which can not be described by such a simple expression, and the interpretation of the Hall coefficient for Fe-based superconductors is also problematic. Here, we investigate thin films of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ with compressive and tensile in-plane strain in a wide range of Co doping. Such in-plane strain changes the band structure of the compounds, resulting in various shifts of the whole phase diagram as a function of Co doping. We show that the resultant phase diagrams for different strain states can be mapped onto a single phase diagram with the Hall number. This universal plot is attributed to the critical fluctuations in multiband systems near the antiferromagnetic transition, which may suggest a direct link between magnetic and superconducting properties in the BaFe$_2$As$_2$ system., Comment: Accepted for publication in Scientific Reports, 6 main figures plus Supplemental Information (8 figures)

Die PET- und fMRT-Bildgebung hat zu einem immensen Zuwachs an Befunden uber die Lokalisation motorischer, kognitiver und affektiver Prozesse im menschlichen Gehirn gefuhrt. Es besteht jedoch eine deutliche Diskrepanz zwischen der grosen Zahl verfugbarer Studien und der eingeschrankten Aussagekraft jedes einzelnen Experiments. Um diese Vielzahl an Befunden moglichst vollstandig objektiv zu integrieren, bieten sich quantitative, koordinatenbasierte Metaanalysen an. Es existiert eine Reihe von verschiedenen Verfahren zu koordinatenbasierten voxelweisen Metaanalysen, von denen sich jedoch die „activation likelihood estimation“ (ALE) weitgehend durchgesetzt hat. Der Beitrag beschreibt die Grundlagen, Methoden und statistische Auswertung der ALE-Metaanalysen sowie ihr Potenzial fur die neurowissenschaftliche Grundlagenforschung und die klinische Hirnforschung.

The human brain exhibits a wide variety of interindividual structural differences like variations in local tissue volume, which are of interest in basic and clinical research. Voxel-based morphometry is an objective approach that enables voxel-wise estimation and statistical comparison of the local amount of a specific tissue. In this article, we describe this method's framework and how it can be used in neuroimaging research.

Highly textured NdFeAs(O,F) thin films have been grown on ion beam assisted deposition (IBAD)-MgO/Y2O3/Hastelloy substrates by molecular beam epitaxy. The oxypnictide coated conductors showed a superconducting transition temperature (Tc) of 43 K with a self-field critical current density (Jc) of 7.0 x 104 A/cm2 at 5 K, more than 20 times higher than powder-in-tube processed SmFeAs(O,F) wires. Albeit higher Tc as well as better crystalline quality than Co-doped BaFe2As2 coated conductors, in-field Jc of NdFeAs(O,F) was lower than that of Co-doped BaFe2As2. These results suggest that grain boundaries in oxypnictides reduce Jc significantly compared to that in Co-doped BaFe2As2 and, hence biaxial texture is necessary for high Jc., 4 pages, 4 figures

Angle-resolved transport measurements revealed that planar defects dominate flux pinning in the investigated Co-doped BaFe2As2 thin film. For any given field and temperature, the critical current depends only on the angle between the crystallographic c-axis and the applied magnetic field but not on the angle between the current and the field. The critical current is therefore limited only by the in-plane component of the Lorentz force but independent of the out-of-plane component, which is entirely balanced by the pinning force exerted by the planar defects. This one-dimensional pinning behavior shows similarities and differences to intrinsic pinning in layered superconductors., Comment: 8 pages, 6 figures

For an investigation concerning the nuclear magnetic moments and their distributions in the nuclei of 7,11Be, an experimental project using laser-microwave double resonance spectroscopy for trapped ions is under progress at INS. Laser cooled ion crystals consisting of a few 9Be+ ions were observed and the ground state hyperfine splitting of 9Be+ was measured with a precision of 10−5. Experiments on the unstable isotope 7Be have been started.

The discovery of superconductivity (SC) with a transition temperature, Tc, up to 65K in single-layer FeSe (bulk Tc =8K) films grown on SrTiO3 substrates has attracted special attention to Fe-based thin films. The high Tc is a consequence of the combined effect of electron transfer from the oxygen-vacant substrate to the FeSe thin film and lattice tensile strain. Here we demonstrate the realization of SC in the parent compound BaFe2As2 (no bulk Tc) just by tensile lattice strain without charge doping. We investigate the interplay between strain and SC in epitaxial BaFe2As2 thin films on Fe-buffered MgAl2O4 single crystalline substrates. The strong interfacial bonding between Fe and the FeAs sublattice increases the Fe-Fe distance due to the lattice misfit which leads to a suppression of the antiferromagnetic spin density wave and induces SC with bulk-Tc ?10K. These results highlight the role of structural changes in controlling the phase diagram of Fe-based superconductors., http://www.nature.com/ncomms/2013/131206/ncomms3877/full/ncomms3877.html

Surface properties of Co-doped BaFe2As2 epitaxial superconducting thin films were inspected by X-ray photoelectron spectroscopy, scanning spreading resistance microscopy (SSRM), and point contact spectroscopy (PCS). It has been shown that surface of Fe-based superconductors degrades rapidly if being exposed to air, what results in suppression of gap-like structure on PCS spectra. Moreover, SSRM measurements revealed inhomogeneous surface conductivity, what is consistent with strong dependence of PCS spectra on contact position. Presented results suggest that fresh surface and small probing area should be assured for surface sensitive measurements like PCS to obtain intrinsic properties of Fe-based superconductors., Comment: 4 pages, 4 figures

We have observed “dark resonances” in theA-type level structure, formed by the 4S1/2 ground state, the 4P1/2 excited state and the low lying metastable 3D3/2 state in the Calcium ion, confined in a Paul radio-frequency trap. These Doppler-free and potentially very narrow resonances were used to determine the magnetic dipole hyperfine interaction constant A for the 4P1/2 and 3D3/2 state of43Ca+, giving −142(8) MHz and −48.3(1.6) MHz, respectively. From measurements of the P-D (E1) and S-D (E2) transition wavelength in a mixture of43Ca+ and40Ca+ we determined the isotope shifts of these lines.

Experiments on Ca+ ions, confined in a Paul trap, deal with the spatial distribution of the fluorescence intensity, from which information on the velocity distribution of an ion cloud can be derived. We obtained laser cooling of a large (about 104) ion cloud. For a few or single trapped ions crystallization, "dark resonances" and quantum jumps have been observed.

Superconducting and normal state transport properties in iron pnictides are sensitive to disorder and impurity scattering. By investigation of Ba(Fe1-xCox)2As2 thin films with varying Co concentration, we demonstrate that in the dirty limit the superconducting dome in the electronic phase diagram of Ba(Fe1-xCox)2As2 shifts towards lower doping concentrations, which differs significantly from observations in single crystals. We show that especially in the underdoped regime superconducting transition temperatures higher than 27 K are possible., Comment: 7 pages, 7 figures

We have performed a laser microwave double resonance experiment on43Ca+ ions stored in a Paul ion trap. The ground state hfs splitting has been determined to Δν=3 225 608 286. 4(3) Hz. The value is corrected for small Zeeman, Stark and second order Doppler shifts as well as for light shift effects caused by the laserfields. The uncertainty is mainly determined by the errors of these corrections.

The lifetime of the metastable 3D3/2 and 3D5/2 states of Ca+ ions is determined in a r.f. ion trap by laser excitation of this levels and subsequent time delayed probing of the state population by a second laser. In a buffer gas atmosphere of about 10−5−10−6 mbar of He we observe quenching to the ground state and strong finestructure mixing of the two D-states. This mixing allowes only the determination of the combined lifetime. Our result of τ(3D)=1.24(39) s is in good agreement with theoretical calculations.

In this paper we propose a unified approach to content-based search in different kinds of music data. Our approach is based on a general algorithmic framework for searching patterns of complex objects in large databases. In particular we describe how this approach may be used to allow for polyphonic search in polyphonic scores as well as for the identification of PCM audio material. We give an overview on the various aspects of our technology including fault tolerant search methods. Several areas of application are suggested. We give an overview on several prototypic systems we developed for those applications including the notify! and the audentify! systems.

The lifetimes of both metastable 3D-levels of Ca+ have been measured using the ion storage technique. Operation at UHV-conditions eliminated the earlier reported problems of collisional finestructure mixing between those states [1], which is inherent to measurements at buffergas background. The results of τ(D 3/2)=1113(45) ms and τ(D 5/2)=1054(61) ms improve our earlier result [1] by almost one order of magnitude and are in good agreement with recent theoretical calculations [3, 4, 5].

To investigate the superconducting properties of iron pnictides we prepared planar hybrid SNS' junctions in thin film technology with a pnictide base electrode, a gold barrier layer and a lead counter electrode. Our design allows characterization of the electrodes and the junction independently in a 4-probe method. We show how both electrodes influence the measured spectra due to their spreading resistance. While the Pb electrode has a constant resistance above its $T_c$, the contribution of the pnictide electrode is clearly current-dependent and thus it needs a more advanced method to be corrected. We present an empirical method, which is simple to apply and allows to deal with the spreading resistance in our junctions to recalculate the actual conductance and voltage of one junction at given temperature.

We present characterization of Ba(Fe1-x Cox) 2As2 thin film using a magneto-optical Kerr effect setup based on photoelastic modulation. The magneto optical technique has been used to analyse the thickness and the temperature dependence of the magnetic properties of epitaxial Ba(Fe1-x Cox)2As2/Fe thin films grown on MgO substrate. The first harmonics, of the reflected laser beam intensity from pnictide thin films is compared with a reference Fe thin film. The hysteretic loops of such samples at room temperature and at 5K are presented.

We present a study of the response to pulsed infrared radiation of Fe-layer shunted pnictide thin film microstructures. The thin film multilayer consisting of 20 nm thick Fe-buffer, 50 nm thick Ba(Fe,Co)2As2 film and gold protection layer were deposited on heated MgO and MgAl2O4 substrates by pulsed-laser deposition. The multilayers were patterned into 5 to 8 um wide and 5 um long microbridges by electron-beam lithography and ion-milling technique. The microbridges show Tc up to 20 K and a critical current density up to 2.56 MA/cm2 at T = 10 K. The photo-response of Fe-shunted Ba(Fe,Co)2As2 thin film microbridges to infrared radiation was studied in a wide range of incident optical power, operation temperature and bias current. We have found that the electron energy relaxation in studied multilayers is dependent on substrate material and is 1.75 times faster in case of MgAl2O4 characterized by lattice matching to pnictide film in comparison to MgO substrate., ASC 2012 submission

We demonstrate the growth of Co-doped BaFe2As2 (Ba-122) thin films on AEF2 (001) (AE: Ca, Sr, Ba) single crystal substrates using pulsed laser deposition. All films are grown epitaxially despite of a large misfit of -10.6% for BaF2 substrate. For all films a reaction layer is formed at the interface confirmed by X-ray diffraction and by transmission electron microscopy. The superconducting transition temperature of the film on CaF2 is around 27 K, whereas the corresponding values of the other films are around 21 K. The Ba-122 on CaF2 shows identical crystalline quality and superconducting properties as films on Fe-buffered MgO., 5 pages, 6 figures, 2 tables

Switched-capacitor (SC) networks are comprised of capacitors interconnected by an array of periodically operated switches. Such networks are particularly attractive in light of the high circuit density possible with MOS circuit technology and hybrid integrated circuits using thin-film and silicon technology. Their implementation and analysis have received increasing attention over the last years, and economical designs find applications in communication and electronic equipment. Previous publications by the author and G. S. Moschytz have shown that SC networks can be analyzed as time-variant sampled-data networks by using nodal charge equations. This led to four-port equivalent circuits in the Z domain, thus modeling the SC network with a time-invariant network. The four-port equivalent circuit was reduced to a two-port, and a two-port transfer function for the entire SC network was derived. This previous work assumed that the network is fed by a staircase input function. In this paper, we show how the theory can be extended to continuous input functions. The results obtained are similar to those obtained by Liou and Kuo, but, since we use traditional two-port theory, the derivation is different. This derivation makes it simple and more intuitively accessible. The interpretation of the analytical expression leads to a bypass circuit that has the properties of a classical ring modulator added to the two-port equivalent circuit mentioned above. We present examples.

This paper describes the analysis of time-variant networks in the frequency domain applied to resistive, inductive, and capacitive sinusoidally varying networks. It leads to a common equivalent circuit. This equivalent circuit is based on some previous work done by Desoer and by the author. The equivalent circuit is applied to the analysis of resistive modulators, parametric amplifiers, and frequency multipliers. It is shown how simple time-invariant two-port equivalent circuits can be derived for these transmission networks, such that the practical engineer can obtain quick insight into their behavior. The derived linear two-port equivalent circuit can be used as a basis for a small-signal nonlinear analysis of the above mentioned transmission networks.

Dihydroquercetin, a white crystalline pentahydroxy-flavanone, occurring in large quantities in Douglas fir and Jeffrey pine barks, was found to be an effective antioxidant for lard, cottonseed oil, and butter oil. This compound imparts no taste and color to fats and oils and, like quercetin, appears to be nontoxic. It was found that 0.03% quercetin was slightly more effective than 0.03% dihydroquercetin as an inhibitor of rancidity in lard. The presence of a small amount of citric acid increased markedly the antioxidant effect of dihydroquercetin on lard. The pentaacetate, pentapropionate, and the pentabenzoate esters of dihydroquercetin showed no antioxidant activity.