1,527 research outputs found
Wide range and tunable linear TMR sensor using two exchange pinned electrodes
A magnetic tunnel junction sensor is proposed, with both the detection and
the reference layers pinned by IrMn. Using the differences in the blocking
temperatures of the IrMn films with different thicknesses, crossed anisotropies
can be induced between the detection and the reference electrodes. The pinning
of the sensing electrode ensures a linear and reversible output. It also allows
tuning both the sensitivity and the linear range of the sensor. The authors
show that the sensitivity varies linearly with the ferromagnetic thickness of
the detection electrode. It is demonstrated that an increased thickness leads
to a rise of sensitivity and a reduction of the operating range
Coulomb-U and magnetic moment collapse in -Pu
The around-the-mean-field version of the LDA+U method is applied to
investigate electron correlation effects in -Pu. It yields a
non-magnetic ground state of Pu, and provides a good agreement with
experimental equilibrium volume, bulk modulus and explains important features
of the photoelectron spectra
On the interplay of waveguide modes and leaky modes in corrugated OLEDs
Bragg gratings incorporated into organic light-emitting diodes (OLEDs) establish a coupling between waveguide modes and useful light (leaky modes). Here we demonstrate that the net coupling direction depends on the OLED stack design. We fabricated two different device structures with gold Bragg gratings. Angle resolved electroluminescence spectra were recorded. For the first device peaks of enhanced emission due to the Bragg grating are observed corresponding to a net energy transfer in direction of the leaky modes. The second device, on the other hand, exhibits dips in the emission spectrum. This reversed direction of energy transfer from the leaky modes to the waveguide modes is explained considering transfer matrix simulations of modal intensity distributions and device emission simulations. An OLED efficiency enhancement is only achieved, if the waveguide mode extraction is dominant
Star formation activity of intermediate redshift cluster galaxies out to the infall regions
We present a spectroscopic analysis of two galaxy clusters out to ~4Mpc at
z~0.2. The two clusters VMF73 and VMF74 identified by Vikhlinin et al. (1998)
were observed with MOSCA at the Calar Alto 3.5m telescope. Both clusters lie in
the ROSAT PSPC field R285 and were selected from the X-ray Dark Cluster Survey
(Gilbank et al. 2004) that provides optical V- and I-band data. VMF73 and VMF74
are located at respective redshifts of z=0.25 and z=0.18 with velocity
dispersions of 671 km/s and 442 km/s, respectively. The spectroscopic
observations reach out to ~2.5 virial radii. Line strength measurements of the
emission lines H_alpha and [OII]3727 are used to assess the star formation
activity of cluster galaxies which show radial and density dependences. The
mean and median of both line strength distributions as well as the fraction of
star forming galaxies increase with increasing clustercentric distance and
decreasing local galaxy density. Except for two galaxies with strong H_alpha
and [OII] emission, all of the cluster galaxies are normal star forming or
passive galaxies. Our results are consistent with other studies that show the
truncation in star formation occurs far from the cluster centre.Comment: 15 pages, 12 figures. A&A in pres
The galaxy populations from the centers to the infall regions in z~0.25 clusters
We conducted a panoramic spectroscopic campaign with MOSCA at the Calar Alto
observatory. We acquired spectra of more than 500 objects. Approximately 150 of
these spectra were of galaxies that are members of six different clusters,
which differ in intrinsic X-ray luminosity. The wavelength range allows us to
quantify the star formation activity by using the OII and the Halpha lines.
This activity is examined in terms of the large-scale environment expressed by
the clustercentric distance of the galaxies as well as on local scales given by
the spatial galaxy densities. A global suppression of star-formation is
detected in the outskirts of clusters, at about 3Rvir. Galaxies with ongoing
star-formation have similar activity, regardless of the environment. Therefore,
the decline of the star-formation activity inside the investigated clusters is
driven mainly by the significant change in the fraction of active versus
passive populations. This suggests that the suppression of the star-formation
activity occurs on short timescales. We detect a significant population of red
star-forming galaxies whose colors are consistent with the red-sequence of
passive galaxies. They appear to be in an intermediate evolutionary stage
between active and passive types. Since a suppression of star-formation
activity is measured at large clustercentric distances and low projected
densities, purely cluster-specific phenomena cannot fully explain the observed
trends. Therefore, as suggested by other studies, group preprocessing may play
an important role in transforming galaxies before they enter into the cluster
environment. Since models predict that a significant fraction of galaxies
observed in the outskirts may have already transversed through the cluster
center, the effects of ram-pressure stripping cannot be neglected. (ABRIDGED)Comment: Revised version. Astronomy and Astrophysics in press. Important typo
correcte
Reversal of the ΔdegP Phenotypes by a Novel rpoE Allele of Escherichia coli
RseA sequesters RpoE (σE) to the inner membrane of Escherichia coli when envelope stress is low. Elevated envelope stress triggers RseA cleavage by the sequential action of two membrane proteases, DegS and RseP, releasing σE to activate an envelope stress reducing pathway. Revertants of a ΔdegP ΔbamB strain, which fails to grow at 37°C due to high envelope stress, harbored mutations in the rseA and rpoE genes. Null and missense rseA mutations constitutively hyper-activated the σE regulon and significantly reduced the major outer membrane protein (OMP) levels. In contrast, a novel rpoE allele, rpoE3, resulting from the partial duplication of the rpoE gene, increased σE levels greater than that seen in the rseA mutant background but did not reduce OMP levels. A σE-dependent RybB::LacZ construct showed only a weak activation of the σE pathway by rpoE3. Despite this, rpoE3 fully reversed the growth and envelope vesiculation phenotypes of ΔdegP. Interestingly, rpoE3 also brought down the modestly activated Cpx envelope stress pathway in the ΔdegP strain to the wild type level, showing the complementary nature of the σE and Cpx pathways. Through employing a labile mutant periplasmic protein, AcrAL222Q, it was determined that the rpoE3 mutation overcomes the ΔdegP phenotypes, in part, by activating a σE-dependent proteolytic pathway. Our data suggest that a reduction in the OMP levels is not intrinsic to the σE-mediated mechanism of lowering envelope stress. They also suggest that under extreme envelope stress, a tight homeostasis loop between RseA and σE may partly be responsible for cell death, and this loop can be broken by mutations that either lower RseA activity or increase σE levels
Multiple Auger cycle photoionisation of manganese atoms by short soft x-ray pulses
The multiple ionisation of atomic Mn, excited at (photon energy: 52.1 eV) and above (photon energy: 61.1 eV) the discrete giant 3p–3d resonance, was studied using high irradiation free-electron-laser soft x-ray pulses from the BL2 beamline of FLASH, DESY, Hamburg. In particular, the impact of the giant resonance on the ionisation mechanism was investigated. Ion mass-over-charge spectra were obtained by means of ion time-of-flight spectrometry. For the two photon energies, the yield of the different ionic charge states Mnq+ (q = 0–7) was determined as a function of the irradiance of the soft x-ray pulses. The maximum charge state observed was Mn6+ for resonant excitation at 52.1 eV and Mn7+ for non-resonant excitation at 61.1 eV at a maximum irradiation of 3×10 13Wcm−2.
.DFG, 170620586, SFB 925: Licht-induzierte Dynamik und Kontrolle korrelierter QuantensystemeBMBF, 05KS7GU2, Verbundprojekt: PIPE - Photon-Ion-Spektrometer an PETRA III. Teilprojekt 2: Entwicklung und Aufbau eines flexiblen Zwei-Strahl Experiments zur Erforschung elektrisch geladener, massenselektierter und zustandspräparierter Ionen (Atome, Cluster und Nanopartikel).BMBF, 05K10GUB, Verbundprojekt PIPE - Photon-Ion-Spektrometer an PETRA III: Photoion-, Photoelektron- und Fluoreszenz-Experimente mit massenselektierten Nanoteilchen. Teilprojekt 2: Ionenfalle und Hochfeldmagnet.BMBF, 05K13GUA, Verbundprojekt 05K2013 - IONSYS: Quellen und Nachweissysteme für innovative Untersuchungen zusammengesetzter ionischer Systeme mit Photonen. Teilprojekt 2.EC/H2020/654220/EU/European Cluster of Advanced Laser Light Sources/EUCAL
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