Qubit-Initialisation and Readout with Finite Coherent Amplitudes in Cavity QED

We consider a unitary transfer of an arbitrary state of a two-level atomic qubit in a cavity to the finite amplitude coherent state cavity field. Such transfer can be used to either provide an effective readout measurement on the atom by a subsequent measurement on the light field or as a method for initializing a fixed atomic state - a so-called "attractor state", studied previously for the case of an infinitely strong cavity field. We show that with a suitable adjustment of the coherent amplitude and evolution time the qubit transfers all its information to the field, attaining a selected state of high purity irrespectively of the initial state.Comment: 6 pages, 4 figure

Adaptive optics testbed for pre- and post-compensation of earth-to-geo optical communication: downlink results

Optical communication between optical ground stations (OGS) and geostationary (GEO) satellites is a promising technology for future high-speed data transfer between Earth and space. However, such optical communication links suffer from distortions caused by atmospheric turbulence. To explore adaptive optics mitigation of this effect both in the uplink and the downlink beam, we have developed an adaptive optics testbed. In an earlier publication [1], we reported on the results of uplink compensation. In this contribution, we wish to elaborate more on the efficiency of downlink compensation. Further, we will highlight the differences between uplink and downlink compensation

Sonoelastography of the Common Flexor Tendon of the Elbow with Histologic Agreement: A Cadaveric Study.

Purpose To determine the correlation of the results of conventional B-mode ultrasonography (US) and compression sonoelastography with histologic results in common flexor tendons of the elbow in human cadavers. Materials and Methods Twenty-five common flexor tendons were evaluated in 16 fresh, unembalmed cadavers of 11 women with a median age of 85 years (range, 71-101 years) and five men with a median age of 78 years (range, 70-88 years). Informed consent was provided according to the last will of the donors. B-mode US results were classified as grade 1, normal tendon with homogeneous fibrillar pattern; grade 2, tendon thickening or hypoechoic areas and/or calcifications in less than 30% of the tendon; or grade 3, hypoechoic areas and/or calcifications greater than 30% of the tendon. Sonoelastographic results were grade 1, blue (hardest) to green (hard); grade 2, yellow (soft); and grade 3, red (softest). The intraclass correlation coefficient was calculated to determine agreement with histologic findings for each B-mode US, sonoelastographic, and combined B-mode US and sonoelastographic examination. Histologic results were grade 1, normal, with parallel fibrillar pattern; grade 2, mild tendinopathy, with cellular infiltration, angiogenesis, or fatty vacuoles; or grade 3, severe tendinopathy, with loss of parallel collagen structure and necrosis. Results Histologic alterations were detected in 44% (11 of 25) of biopsy specimens. Intraclass correlation with histologic results was 0.57 for B-mode US, 0.68 for sonoelastography, and 0.84 for the combination of the two approaches. Conclusion The addition of sonoelastography to B-mode US provided statistically significant improvement in correlation with histologic results compared with the use of B-mode US alone (P \u3c .02). (©) RSNA, 2016 Online supplemental material is available for this article

Film thickness measurements in a running hydrostatic unit using ultrasound

The present paper describes the measurement of the oil film thickness in the range of a few micrometers in an operating hydrostatic unit using ultrasound. The investigated tribological system consists of a rotating steel cylinder block and a stationary bi-metal valve plate under static and hydrodynamic lubrication. The film thickness has been recorded in a wide range of operating conditions, pressure between 100 to 300 bar and rotational speed between 500 and 3000 rpm, to support a deeper understanding of the system. Temperature sensors were implemented next to the ultrasound sensors to compensate the ultrasound signal amplitude and phase change due to temperature dependent acoustic impedances. To confirm the results, especially the presence of deliberate zero-film conditions, wear profiles of the running surface were taken. The ultrasound technique also allows the real-time observation of film thickness oscillations with shaft and piston frequency. Steady-state measurements confirm the system behavior observed in transient operation and zero-film conditions with respect to hardware configuration were detected. The findings will be utilized to support current product development activities and to validate and improve simulation models used for film thickness predictions

Structure and mechanism of the RNA dependent RNase Cas13a from Rhodobacter capsulatus

Cas13a are single-molecule effectors of the Class II, Type VI family of CRISPR-Cas systems that are part of the bacterial and archaeal defense systems. These RNA-guided and RNA-activated RNA endonucleases are characterized by their ability to cleave target RNAs complementary to the crRNA-spacer sequence, as well as bystander RNAs in a sequence-unspecific manner. Due to cleavage of cellular transcripts they induce dormancy in the host cell and thus protect the bacterial population by aborting the infectious cycle of RNA-phages. Here we report the structural and functional characterization of a Cas13a enzyme from the photo-auxotrophic purple bacteria Rhodobacter capsulatus. The X-ray crystal structure of the RcCas13a-crRNA complex reveals its distinct crRNA recognition mode as well as the enzyme in its contracted, pre-activation conformation. Using site-directed mutagenesis in combination with mass spectrometry, we identified key residues responsible for pre-crRNA processing by RcCas13a in its distinct catalytic site, and elucidated the acid-base mediated cleavage reaction mechanism. In addition, RcCas13a cleaves target-RNA as well as bystander-RNAs in Escherichia coli which requires its catalytic active HEPN (higher eukaryotes and prokaryotes nucleotide binding) domain nuclease activity. Our data provide further insights into the molecular mechanisms and function of this intriguing family of RNA-dependent RNA endonucleases that are already employed as efficient tools for RNA detection and regulation of gene expression

Combining Carbon Nanoparticle Coatings and Laser Surface Texturing for Enhanced Lubricity Under High Loads

Developing new lubrication concepts greatly contributes to improving the energy efciency of mechanical systems. Nanoparticles such as those based on carbon allotropes or 2D materials have received widespread attention due to their outstanding mechanical and tribological performance. However, these systems are limited by a short wear life. Combining nanoparticle coatings with laser surface texturing has been demonstrated to substantially improve their durability due to the reservoir efect which prevents immediate particle removal from the contact. In this study, we investigate the high-load (20 N) tribological performance of AISI 304 austenitic stainless-steel substrates, which are line-patterned by laser interference patterning and subsequently coated with diferent carbon nanoparticle coatings (carbon nanotubes, carbon onions, carbon nanohorns) against alumina and 100Cr6 counter bodies. In addition to that, benchmark testing is performed with conventional solid lubricant coatings (graphite, MoS2, WS2). Electrophoretic deposition is used as the main coating technique along with air spraying (for WS2). All coatings substantially improve friction compared to the purely laser-patterned reference. Among all coating materials, carbon nanotubes demonstrate superior lubricity and the longest wear life against 100Cr6 and alumina counter bodies. Detailed characterization of the resulting wear tracks by energy-dispersive X-ray spectroscopy, scanning electron microscopy, and confocal laser scanning microscopy provides insights into the friction mechanisms of the various solid lubricant particles. Further, material transfer is identifed as an important aspect for efective and long-lasting lubrication