Nonperturbative analysis of coupled quantum dots in a phonon bath

Transport through coupled quantum dots in a phonon bath is studied using the recently developed real-time renormalization-group method. Thereby, the problem can be treated beyond perturbation theory regarding the complete interaction. A reliable solution for the stationary tunnel current is obtained for the case of moderately strong couplings of the dots to the leads and to the phonon bath. Any other parameter is arbitrary, and the complete electron-phonon interaction is taken into account. Experimental results are quantitatively reproduced by taking into account a finite extension of the wavefunctions within the dots. Its dependence on the energy difference between the dots is derived.Comment: 8 pages, 6 figure

Real-Time-RG Analysis of the Dynamics of the Spin-Boson Model

Using a real-time renormalization group method we determine the complete dynamics of the spin-boson model with ohmic dissipation for coupling strengths $\alpha\lesssim 0.1-0.2$. We calculate the relaxation and dephasing time, the static susceptibility and correlation functions. Our results are consistent with quantum Monte Carlo simulations and the Shiba relation. We present for the first time reliable results for finite cutoff and finite bias in a regime where perturbation theory in $\alpha$ or in tunneling breaks down. Furthermore, an unambigious comparism to results from the Kondo model is achieved.Comment: 4 pages, 5 figures, 1 tabl

Magnetic resonance imaging of vaginal support structure before and after Vecchietti procedure in women with Mayer–Rokitansky–Küster–Hauser syndrome

IntroductionIt is unclear how pelvic floor supporting structures might be affected by the absence of the vagina. It was the aim of this prospective study to analyze the magnetic resonance imaging morphology of pelvic support prior and after a Vecchietti procedure in women suffering Mullerian agenesis (Mayer–Rokitansky–Küster–Hauser syndrome).Material and methods26 women with a diagnosis of Mayer–Rokitansky–Küster–Hauser syndrome associated vaginal agenesis were recruited prospectively prior to the laparoscopic creation of a neovagina according to the Vecchietti procedure. The primary outcome measure was the magnetic resonance imaging morphology of supporting structures. Secondary outcome measures were anatomical and functional vaginal length. Follow up was conducted six months after surgery.ResultsTwenty‐six women were analyzed. Mean age was 19.8 ± 4.4 years (±SD) and mean body mass index was 23.7 ± 4.3 kg/m2 (±SD). All were Caucasian. Supporting structures consistent with cardinal and uterosacral ligaments were visible on magnetic resonance imaging in all cases (100%). There were no levator ani defects. The vaginal apex could be visualized postoperatively in 12 women (46.2%) reaching up to Level I. The vagina was visible in both Level II and III with normal relations to the pelvic walls in all cases. On gynecological examination, vaginal length was 8.8 ± 2.1 cm (mean ± SD) anatomically and 10.2 ± 2.2 cm (mean ± SD) functionally.ConclusionsThe preoperative presence of pelvic support structures into which the vagina is lengthened by the surgery likely explains the uncommon occurrence of vaginal prolapse in women who had the Vecchietti procedure.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144648/1/aogs13350_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144648/2/aogs13350.pd

Lumbar Spinal Stenosis: Ipsilateral Facet-sparing Unilateral Laminotomy for Bilateral Decompression: Technical Note and Preliminary Results

Microsurgical unilateral laminotomy for bilateral decompression (ULBD) decompresses effectively lumbar stenosis. Whenever low grade degenerative spondylolisthesis, sagittal oriented facet joints, scoliotic deformity, tall disc, and obesity jeopardize postoperative segmental stability, a maximum facet-preserving decompression is desirable. The medialized ULBD (mULBD) aims to preserve the facet joint on the approach side. Sixty-four patients presenting with neurogenic claudication underwent single or multilevel decompression with ULBD or mULBD according to the judgement of the surgeon. The volume of the target facet joints and the dural cross sectional area (CT-DCSA) were measured pre- and postoperatively by an ultra-low-dose CT with a specific software. Forty-three pairs of facet joints were addressed with ULBD and 43 pairs with mULBD. Postoperatively, the mean percentage of the preoperative facet joint volume preserved on the approach side was 70% ± 4% (ULBD) and 88% ± 6% (mULBD); (p<0.001). The mean facet joint volume preserved contraleral to the approach side was 87% ± 6% (ULBD) and 91% ± 6% (mULBD); (p=0.4). The mean postoperative CT-DCSA was 152 ± 30 mm² (ULBD) and 153 ± 26 mm² (mULBD); (p=0.43). The mUBLD decompresses lumbar spinal stenosis effectively as ULBD and preserves better the facet joint on the approach side

The GRAVITY instrument software / High-level software

GRAVITY is the four-beam, near- infrared, AO-assisted, fringe tracking, astrometric and imaging instrument for the Very Large Telescope Interferometer (VLTI). It is requiring the development of one of the most complex instrument software systems ever built for an ESO instrument. Apart from its many interfaces and interdependencies, one of the most challenging aspects is the overall performance and stability of this complex system. The three infrared detectors and the fast reflective memory network (RMN) recorder contribute a total data rate of up to 20 MiB/s accumulating to a maximum of 250 GiB of data per night. The detectors, the two instrument Local Control Units (LCUs) as well as the five LCUs running applications under TAC (Tools for Advanced Control) architecture, are interconnected with fast Ethernet, RMN fibers and dedicated fiber connections as well as signals for the time synchronization. Here we give a simplified overview of all subsystems of GRAVITY and their interfaces and discuss two examples of high-level applications during observations: the acquisition procedure and the gathering and merging of data to the final FITS file.Comment: 8 pages, 7 figures, published in Proc. SPIE 9146, Optical and Infrared Interferometry IV, 91462

VLTI status update: a decade of operations and beyond

We present the latest update of the European Southern Observatory's Very Large Telescope interferometer (VLTI). The operations of VLTI have greatly improved in the past years: reduction of the execution time; better offering of telescopes configurations; improvements on AMBER limiting magnitudes; study of polarization effects and control for single mode fibres; fringe tracking real time data, etc. We present some of these improvements and also quantify the operational improvements using a performance metric. We take the opportunity of the first decade of operations to reflect on the VLTI community which is analyzed quantitatively and qualitatively. Finally, we present briefly the preparatory work for the arrival of the second generation instruments GRAVITY and MATISSE.Comment: 10 pages, 7 figures, Proceedings of the SPIE, 9146-1

AMBER : a near infrared focal instrument for the VLTI

10 pagesInternational audienceAMBER is the General User near-infrared focal instrument of the Very Large Telescope interferometer. Its specifications are based on three key programs on Young Stellar Objects, Active Galactic Nuclei central regions, masses and spectra of hot Extra Solar Planets. It has an imaging capacity because it combines up to three beams and very high accuracy measurement are expected from the spatial filtering of beams by single mode fibers and the comparison of measurements made simultaneously in different spectral channels

Thermal background fluctuations at 10 micron measured with VLTI/MIDI

International audienc