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81.
Using nonequilibrium dynamical mean-field theory, we compute the time evolution of the current in a Mott insulator after a strong electric field is turned on. We observe the formation of a quasistationary state in which the current is almost time independent although the system is constantly excited. At moderately strong fields this state is stable for quite long times. The stationary current exhibits a threshold behavior as a function of the field, in which the threshold increases with the Coulomb interaction and vanishes as the metal-insulator transition is approached. 相似文献
82.
Kampschulte T Alt W Brakhane S Eckstein M Reimann R Widera A Meschede D 《Physical review letters》2010,105(15):153603
We experimentally demonstrate the elementary case of electromagnetically induced transparency with a single atom inside an optical cavity probed by a weak field. We observe the modification of the dispersive and absorptive properties of the atom by changing the frequency of a control light field. Moreover, a strong cooling effect has been observed at two-photon resonance, increasing the storage time of our atoms twenty-fold to about 16 seconds. Our result points towards all-optical switching with single photons. 相似文献
83.
A. Knizhnik G.M. Reisner G.E. Shter Y. Eckstein 《Journal of Physics and Chemistry of Solids》2003,64(2):273-280
Liquid nitrogen, liquid oxygen and liquid argon were tested as coolers for quenching performed after equilibrium of (CaxLa1−x)(Ba1.75−xLa0.25+x)Cu3Oy (x=0.1 or 0.4) with oxygen has been attained. This compound has been previously denoted as CLBLCO, CLBCO or CaLaBaCuO. Absorption of O2 during quenching in liquid oxygen was found and measured. Such samples are oxygen inhomogeneous. The transition to superconductivity is wide and begins 20 K higher than for a homogeneous sample having the same oxygen content. Liquid nitrogen, which is usually used as an external cooling agent containing 2-3% of oxygen, also leads to notable oxygen absorption. Only quenching in oxygen free liquid argon or in oxygen free liquid nitrogen does not cause oxygen absorption and may be used for the preparation of homogeneous samples of CLBLCO after equilibration at any temperature in the range from 300 to 950 °C. 相似文献
84.
Using nonequilibrium dynamical mean-field theory, we study the isolated Hubbard model in a static electric field in the limit of weak interactions. Linear response behavior is established at long times, but only if the interaction exceeds a critical value, below which the system exhibits an ac-type response with Bloch oscillations. The transition from ac to dc response is defined in terms of the universal long-time behavior of the system, which does not depend on the initial condition. 相似文献
85.
Blázquez-Sánchez D Weichelt B Austerschulte A Voss A Graf T Killi A Eckstein HC Stumpf M Matthes AL Zeitner UD 《Optics letters》2011,36(6):799-801
We report on results obtained with an aspherical mirror to compensate for the phase front aberrations of a cw thin-disk laser with a single disk in the resonator. A record output power of 5?kW with a beam quality suitable for laser cutting (beam propagation factor M2=9.2) has been achieved. 相似文献
86.
This paper develops a new error criterion for the approximate minimization of augmented Lagrangian subproblems. This criterion is practical since it is readily testable given only a gradient (or subgradient) of the augmented Lagrangian. It is also “relative” in the sense of relative error criteria for proximal point algorithms: in particular, it uses a single relative tolerance parameter, rather than a summable parameter sequence. Our analysis first describes an abstract version of the criterion within Rockafellar’s general parametric convex duality framework, and proves a global convergence result for the resulting algorithm. Specializing this algorithm to a standard formulation of convex programming produces a version of the classical augmented Lagrangian method with a novel inexact solution condition for the subproblems. Finally, we present computational results drawn from the CUTE test set—including many nonconvex problems—indicating that the approach works well in practice. 相似文献
87.
Depth proliles of 6.6 keV D+ implanted into titanium in the temperature range between 140 K and 500 K have been studied using the D(3He, α) H nuclear reaction. At 140 K the trapped amount is close to 100% at low doses and reaches saturation at about 2 × 1018D/cm2, whereas at room temperature no saturation could be reached up to 2 × 1019 D/cm2. At higher temperatures the amount decreases until no deuterium could be detected in the surface layer above 500 K. The depth profiles are strongly dependent on temperature. At 140 K the deuterium is found in a surface layer of about 2000 Å with a maximum ratio of deuterium to metal atoms of 2.5. At room temperature a hydride layer of TiD1.8, forms. The thickness of the hydride layer depends on deuterium dose and extends to 1.5 μm at 2 × 1019 D/cm2. At higher temperatures the atom concentrations are lower and the deuterium seems to diffuse deeply into the bulk. These results are discussed in terms of diffusion of deuterium i n Ti and titanium hydride. 相似文献
88.
Edna Bode Antje K. Heinrich Merle Hirschmann Desalegne Abebew Yan‐Ni Shi Tien Duy Vo Frank Wesche Yi‐Ming Shi Peter Grün Svenja Simonyi Nadine Keller Yvonne Engel Sebastian Wenski Reuel Bennet Sophie Beyer Iris Bischoff Anthony Buaya Sophie Brandt Ibrahim Cakmak Harun imen Simone Eckstein Denia Frank Robert Fürst Martin Gand Gerd Geisslinger Selcuk Hazir Marina Henke Ralf Heermann Virginie Lecaudey Wilhelm Schfer Susanne Schiffmann Anja Schüffler Rebecca Schwenk Marisa Skaljac Eckhard Thines Marco Thines Thomas Ulshfer Andreas Vilcinskas Thomas A. Wichelhaus Helge B. Bode 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19288-19288
89.
W. Eckstein 《辐射效应与固体损伤》2013,168(1):239-250
Abstract The changes of the program TRIM.SP namely the vectorization and other minor changes since its first publication in 1984 are shortly described. Examples especially about backscattering and sputtering illustrate the possibilities which can be handled by the program. 相似文献
90.
Edna Bode Antje K. Heinrich Merle Hirschmann Desalegne Abebew Yan‐Ni Shi Tien Duy Vo Frank Wesche Yi‐Ming Shi Peter Grün Svenja Simonyi Nadine Keller Yvonne Engel Sebastian Wenski Reuel Bennet Sophie Beyer Iris Bischoff Anthony Buaya Sophie Brandt Ibrahim Cakmak Harun imen Simone Eckstein Denia Frank Robert Fürst Martin Gand Gerd Geisslinger Selcuk Hazir Marina Henke Ralf Heermann Virginie Lecaudey Wilhelm Schfer Susanne Schiffmann Anja Schüffler Rebecca Schwenk Marisa Skaljac Eckhard Thines Marco Thines Thomas Ulshfer Andreas Vilcinskas Thomas A. Wichelhaus Helge B. Bode 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19133-19139
Natural products (NPs) from microorganisms have been important sources for discovering new therapeutic and chemical entities. While their corresponding biosynthetic gene clusters (BGCs) can be easily identified by gene‐sequence‐similarity‐based bioinformatics strategies, the actual access to these NPs for structure elucidation and bioactivity testing remains difficult. Deletion of the gene encoding the RNA chaperone, Hfq, results in strains losing the production of most NPs. By exchanging the native promoter of a desired BGC against an inducible promoter in Δhfq mutants, almost exclusive production of the corresponding NP from the targeted BGC in Photorhabdus, Xenorhabdus and Pseudomonas was observed including the production of several new NPs derived from previously uncharacterized non‐ribosomal peptide synthetases (NRPS). This easyPACId approach (easy Promoter Activated Compound Identification) facilitates NP identification due to low interference from other NPs. Moreover, it allows direct bioactivity testing of supernatants containing secreted NPs, without laborious purification. 相似文献