321 research outputs found
Measurement-induced macroscopic superposition states in cavity optomechanics
We present a novel proposal for generating quantum superpositions of
macroscopically distinct states of a bulk mechanical oscillator, compatible
with existing optomechanical devices operating in the readily achievable
bad-cavity limit. The scheme is based on a pulsed cavity optomechanical quantum
non-demolition (QND) interaction, driven by displaced non-Gaussian states, and
measurement-induced feedback, avoiding the need for strong single-photon
optomechanical coupling. Furthermore, we show that single-quadrature cooling of
the mechanical oscillator is sufficient for efficient state preparation, and we
outline a three-pulse protocol comprising a sequence of QND interactions for
squeezing-enhanced cooling, state preparation, and tomography.Comment: 7 pages, 5 figure
Results of four years of digital urban monitoring of Rattus norvegicus with RatMap in Hamburg including data on infestation near the surface and in underground sewers
Plenge-Bönig, A., Zickert, A., Baumgardt, K., Sammann, A
Quadrupole collectivity in 128Cd
The regions around shell closures, especially around doubly magic nuclei, are of major interest in nuclear structure physics, as they provide a perfect test for nuclear structure theory. The neutron-rich Cd isotopes in the region of 132Sn are only two protons away from the shell closure at Z=50 and in close proximity to the N=82 magic number. Nevertheless they show an irregular behaviour regarding
the excitation energy of the first excited 2+ state. This is not reproduced by shell model calculations, which is astonishing due to the proximity of the shell closures. In order to shed light on the much discussed region around doubly magic 132Sn, a Coulomb excitation experiment of 128Cd has been performed at REX-ISOLDE, CERN. The reduced transition strength B(E2;0+_gs → 2+_1), which is a measure of
collectivity, and the spectroscopic quadrupole moment Q_s(2+_1) as a measure of deformation could be determined for the first time. The results are shown as the continuation of already measured neutron-rich Cd isotopes and are compared to both beyond mean field and shell model calculations, which give different predictions for these observables
Accuracy and Immersion Improvement of Hybrid Motion Capture based Real Time Virtual Validation
AbstractUsing a digital human model for dynamic analysis is due to the high modelling complexity in digital environments not very prevalent. The movement of the worker is either unrealistic, or time-consuming to realize. Therefore, the need for research is a time saving possibility to explore virtual validation by a human model taking advantage of a nonetheless realistic movement design. To achieve this goal, we use an experimental setup including both a hybrid motion capture system and an interface for the connection to digital validation software. The motion capturing in connection along with the validation software allows real time modelling respectively tracking and therefore a realistic movement of the human model. To get good results while applying the motion capturing approach in mixed reality situations, it is necessary to have an exact registration between the real and virtual environment. Hence, the experimental setup must be designed for both. The key challenge here is to superimpose the CAD data with the real objects used for haptic feedback and better immersion. To realize an optimal registration we use a laser tracker solution
Systematic site-directed mutagenesis of the Helicobacter pylori CagL protein of the Cag type IV secretion system identifies novel functional domains
The Cag Type IV secretion system, which contributes to inflammation and cancerogenesis during chronic infection, is one of the major virulence factors of the bacterial gastric pathogen Helicobacter pylori. We have generated and characterized a series of non-marked site-directed chromosomal mutants in H. pylori to define domains of unknown function of the essential tip protein CagL of the Cag secretion system. Characterizing the CagL mutants, we determined that their function to activate cells and transport the effector CagA was reduced to different extents. We identified three novel regions of the CagL protein, involved in its structural integrity, its possible interaction with the CagPAIT4SS pilus protein CagI, and in its binding to integrins and other host cell ligands. In particular two novel variable CagL motifs were involved in integrin binding, TSPSA, and TASLI, which is located opposite of its integrin binding motif RGD. We thereby defined functionally important subdomains within the CagL structure, which can be used to clarify CagL contributions in the context of other CagPAI proteins or for inhibition of the CagT4SS. This structure-function correlation of CagL domains can also be instructive for the functional characterization of other potential VirB5 orthologs whose structure is not yet known
Systematic site-directed mutagenesis of the Helicobacter pylori CagL protein of the Cag type IV secretion system identifies novel functional domains
The Cag Type IV secretion system, which contributes to inflammation and cancerogenesis during chronic infection, is one of the major virulence factors of the bacterial gastric pathogen Helicobacter pylori. We have generated and characterized a series of non-marked site-directed chromosomal mutants in H. pylori to define domains of unknown function of the essential tip protein CagL of the Cag secretion system. Characterizing the CagL mutants, we determined that their function to activate cells and transport the effector CagA was reduced to different extents. We identified three novel regions of the CagL protein, involved in its structural integrity, its possible interaction with the CagPAIT4SS pilus protein CagI, and in its binding to integrins and other host cell ligands. In particular two novel variable CagL motifs were involved in integrin binding, TSPSA, and TASLI, which is located opposite of its integrin binding motif RGD. We thereby defined functionally important subdomains within the CagL structure, which can be used to clarify CagL contributions in the context of other CagPAI proteins or for inhibition of the CagT4SS. This structure-function correlation of CagL domains can also be instructive for the functional characterization of other potential VirB5 orthologs whose structure is not yet known
Backflow in a Fermi Liquid
We calculate the backflow current around a fixed impurity in a Fermi liquid.
The leading contribution at long distances is radial and proportional to 1/r^2.
It is caused by the current induced density modulation first discussed by
Landauer. The familiar 1/r^3 dipolar backflow obtained in linear response by
Pines and Nozieres is only the next to leading term, whose strength is
calculated here to all orders in the scattering. In the charged case the
condition of perfect screening gives rise to a novel sum rule for the phase
shifts. Similar to the behavior in a classical viscous liquid, the friction
force is due only to the leading contribution in the backflow while the dipolar
term does not contribute.Comment: 4 pages, 1 postscript figure, uses ReVTeX and epsfig macro, submitted
to Physical Review Letter
Longitudinal Force on a Moving Potential
We show a formal result of the longitudinal force acting on a moving
potential. The potential can be velocity-dependent, which appears in various
interesting physical systems, such as electrons in the presence of a magnetic
flux-line, or phonons scattering off a moving vortex. By using the phase-shift
analysis, we are able to show the equivalence between the adiabatic
perturbation theory and the kinetic theory for the longitudinal force in the
dilute gas limit.Comment: RevTeX, 4 pages, revised tex
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