We extend the concept of superadiabatic dynamics, or transitionless quantum driving, to quantum open systems whose evolution is governed by a master equation in the Lindblad form. We provide the ...general framework needed to determine the control strategy required to achieve superadiabaticity. We apply our formalism to two examples consisting of a two-level system coupled to environments with time-dependent bath operators.
The New Advanced Telescope for High ENergy Astrophysics (NewAthena) will be the largest space‐based X‐ray observatory ever built. It will have an effective area above 1.1 m2 at 1 keV, which ...corresponds to a polished mirror surface of about 300 m2 due to the grazing incidence. As such a mirror area is not achievable with an acceptable mass even with nested shells, silicon pore optics (SPO) technology will be utilized. In the PTB laboratory at BESSY II, two dedicated beamlines are in use for their characterization with monochromatic radiation at 1 keV and a low divergence well below 2 arcsec: the X‐ray Pencil Beam Facility (XPBF 1) and the X‐ray Parallel Beam Facility (XPBF 2.0), where beam sizes up to 8 mm × 8 mm are available while maintaining low beam divergence. This beamline is used for characterizing mirror stacks and controlling the focusing properties of mirror modules (MMs) – consisting of four mirror stacks – during their assembly at the beamline. A movable CCD based camera system 12 m from the MM registers the direct and the reflected beams. The positioning of the detector is verified by a laser tracker. The energy‐dependent reflectance in double reflection through the pores of an MM with an Ir coating was measured at the PTB four‐crystal monochromator beamline in the photon energy range 1.75 keV to 10 keV, revealing the effects of the Ir M edges. The measured reflectance properties are in agreement with the design values to achieve the envisaged effective area.
Mirror modules for the optics of the X‐ray observatory NewAthena are assembled and characterized at dedicated synchrotron radiation beamlines. The reflectance of a fully assembled and coated module was determined in a wide energy range.
The dynamical Casimir effect (DCE) predicts the generation of photons from the vacuum due to the parametric amplification of the quantum fluctuations of an electromagnetic field. The verification of ...such an effect is still elusive in optical systems due to the very demanding requirements of its experimental implementation. We show that an ensemble of two-level atoms collectively coupled to the electromagnetic field of a cavity, driven at low frequencies and close to a quantum phase transition, stimulates the production of photons from the vacuum. This paves the way to an effective simulation of the DCE through a mechanism that has recently found experimental demonstration. The spectral properties of the emitted radiation reflect the critical nature of the system and allow us to link the detection of the DCE to the Kibble-Zurek mechanism for the production of defects when crossing a continuous phase transition.
Abstract Appropriate targets for catheter ablation of atrial fibrillation (AFib) beyond pulmonary vein isolation (PVI) are still controversially discussed. Various approaches such as ablation of ...complex fractionated atrial electrograms (EGMs), areas with spatio-temporal dispersion, and areas with increased rotor density have not been reproducible or failed to improve clinical success rates. The local cycle length (CL) and duty cycle (DC) distribution during AFib offer novel measures to characterize the atrial substrate. This study aims at providing first insights into the inter-individual variability of observed CL and DC distributions, their interdependence, and their correlation to the duration of AFib episodes to improve the individual characterization of the AFib substrate and tailor ablation strategies in future. In patients with recurrence of AFib despite PVI, a high-resolution 3D map was recorded at baseline during AFib. Intracardiac EGMs were preprocessed to improve local signal quality and far field suppression. EGMs were recorded with the multipolar, basket-shaped high-density mapping catheter. Local CL and DC distribution were visualized using a scatter plot and histograms. CL quantifies the time between subsequent local activations, DC quantifies the fraction of CL with local EGM activity, and the confidence (conf) feature quantifies the spatiotemporal consistency of EGM morphology. Only EGMs with conf > 0.6 are analysed. Feature calculation does not only take into account single EGMs but a weighted conglomerate of all acquisitions within a series of beats. Adjustable CL and DC thresholds allow highlighting regions within the 3D map for individual spatial analysis. 14 patients (7x paroxysmal AFib, 7x persistent AFib) were enrolled. All subjects underwent repeat ablation after PVI due to recurrence of AFib. CL and DC histograms were of highly individual shape. The most prevalent feature value varied from 158ms to 263ms for CL and from 38% to 96% for DC; histogram widths (inter-quartile-range) from 10ms to 34ms and from 26% to 36%, respectively. Normal distributions, multimodal distributions, and skewed distributions exhibiting a dominant peak were observed for CL. Both the most prevalent CL and the width of the distribution were highly individual. DC was observed to be normally to equally distributed with mostly broad bandwidths. Linear regression revealed a positive dependency between the most prevalent CL and the width of CL distributions. The most prevalent value and the width of both CL and DC did not differ significantly for the paroxysmal and persistent subgroup. Compare figure for detailed results. CL and DC distributions can help to characterize the highly individual type of AFib. The presented results suggest that there will not be a one-size-fits-all ablation approach for the AFib substrate. Further research is needed to identify clusters of similar pattern and individually adjust the ablation strategy.
Abstract Appropriate targets for catheter ablation of atrial fibrillation (AFib) beyond pulmonary vein isolation (PVI) are still controversially discussed. Since available parameters to analyze the ...vulnerable substrate are very limited, there is the need to define and understand tailored features. Mapping during AFib can be particularly challenging due to its non-repetitive nature. Amongst others, temporal stability despite changing activation sequences is an essential requirement for features applied to AFib maps. The local cycle length (CL) and duty cycle (DC) offer novel measures to characterize the atrial substrate during AFib. This study aims at providing first insights into the temporal stability of CL and DC during AFib in order to assess the suitability of both features for the characterization of the individual substrate and tailor ablation strategies in future. In patients with recurrent AFib after PVI, two high-resolution 3D electro-anatomical maps were recorded sequentially during AFib before any ablation. Intracardiac electrograms (EGMs) were preprocessed to improve local signal quality and far field suppression. EGMs were recorded with a multipolar, basket-shaped high-density mapping catheter. Local CL and DC distribution were visualized using scatter plots and histograms. CL quantifies the time between subsequent local activations, DC quantifies the fraction of CL with local EGM activity, and the confidence (conf) feature quantifies the spatiotemporal consistency of EGM morphology. Only recordings with conf > 0.6 are analyzed. Feature calculation is based on a weighted conglomerate of all acquisitions within a series of beats. Adjustable CL and DC thresholds allow highlighting regions within the 3D map for individual spatial analysis. Both the global distributions and the local occurrence of CL and DC were compared in order to assess temporal stability. Four patients (2x paroxysmal AFib, 2x persistent AFib) were enrolled. All subjects underwent repeat ablation after PVI due to recurrence of AFib. Table 1 summarizes mapping parameters for both AFib maps in individual patients. Despite differences in mapping time and the number of EGMs, CL and DC histograms were significantly similar when comparing maps within one patient. For individually selected ranges of CL and DC in the upper left corner of the scatter plot (short CL and high DC), localization of corresponding areas was comparable in both 3D maps. An example is shown for patient I in the left and central column of the figure. CL and DC distributions were temporally stable features for all patients in this study cohort. Localization of EGMs of given CL and DC range within the 3D maps were comparable but not identical for arbitrarily selected ranges. CL and DC can therefore be considered valid features for substrate characterization during AFib. Further studies will need to investigate how ablation strategies can be derived from individual CL and DC distributions.
Abstract Introduction Ventricular tachycardia (VT) ablation in patients with progressed heart failure (HF) is known to be complex and associated with a high periprocedural risk and mortality, in part ...due due to hemodynamic instability during ongoingVTs. Use of mechanical circulatory support (MCS) systems has been already implemented in complex high-risk percutaneous coronary intervention (CHIP-PCI) workflows. Use and benefit of MCS in VT ablation is still under debate. MCS protected VT ablation (proVT-A) might be associated with improved clinical outcomebut potentially comes along with an increased risk of periprocedural complications. Based on data of four German high-volume centers we aimed to analyze retrospective data on patient characteristics and impact of proVT-A with respect to safety and mid-term efficacy. Methods All patients undergoing proVT-A as a primary approach from four German EP centers were included in the analysis. Use of MCS in bailout scenariosin VT ablation were not included. Patient characteristics, procedural parameters and clinical outcome were evaluated. The primary endpoint was a combined endpoint of VT/VF recurrence and all-cause death. Results 41 patients who underwent proVT-A were included. Mean age was 64±11a, 92% of patients were male (38/41), 65% (27/41) suffered from ischemic cardiomyopathy, mean left ventricular ejection fraction was 33±13%,76% (31/41) of patients presented with a documented hemodynamically not tolerated VT, mean PAAIN-ESD score was 13±7, and 46% (19/41) had a history of a previous VT ablation w/o MCS. During proVT-A procedure at least one VT was inducible and mappable in 35 patients (85%). Acute procedural success was 85%, with only n=6 patients remaining inducible for VT. Mean procedure duration was 245±46min. With respect to periprocedural safety (30days)a total of n=12 relevant procedural complications were reported in 8 patients. This included n=5 vascular access complications, of which n=3 requiring transfusion or surgery. One case of periprocedural death was reported 6h post proVT-A due to PEA. Three patients developed pericardial effusion, one requiring drainage. Freedom from VT/VF was 78% (n=9 VT/VF recurrences) after a mean follow-up (FU) of 15±14 months (figure 1A). Death of any cause occurred in n=9 patients (figure 1B). In summary, after a mean FU of 15±14 months n=16 patients (39%) met the combined endpoint of VT/VF recurrence and all-cause death (figure 1C). Conclusion Patients enrolled in the German PROTECT VT Registry had significant cardiovascular comorbidities and therefore represent a high-risk population for VT ablation. Use of MCS was feasible, comparably safe, associated with high procedural and promising long-term success rate. These results highlight the need for larger registries and future prospective trials evaluating the potential benefit of proVT-A in selected patients. Further, it should be aimed for optimization of periprocedural vascular access site management.
The Sentinel-5 Precursor satellite was successfully launched on 13 October 2017, carrying the Tropospheric Monitoring Instrument (TROPOMI) as its single payload. TROPOMI is the next-generation ...atmospheric sounding instrument, continuing the successes of GOME, SCIAMACHY, OMI, and OMPS, with higher spatial resolution, improved sensitivity, and extended wavelength range. The instrument contains four spectrometers, divided over two modules sharing a common telescope, measuring the ultraviolet, visible, near-infrared, and shortwave infrared reflectance of the Earth. The imaging system enables daily global coverage using a push-broom configuration, with a spatial resolution as low as 7Ã3.5 km.sup.2 in nadir from a Sun-synchronous orbit at 824 km and an Equator crossing time of 13:30 local solar time.
A pilot study has been carried out to simulate stochastic gravitational wave background originating from first order phase transitions in the early universe. The space based gravitational wave ...detector LISA will be operational in the range of 10-4 to 0.1 Hz and could be sensitive to the red shifted gravitational waves from cosmological origin. In this study we have modeled the signals from first order phase transitions and we compared the signal both with the expected instrumental noise and realistic simulated foreground signals, originating from the white dwarf population in our galaxy.
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