Enhanced Photoconductivity at Dislocations in SrTiO₃

Dislocations are 1D crystallographic line defects and are usually seen as detrimental to the functional properties of classic semiconductors. It is shown here that this not necessarily accounts for oxide semiconductors in which dislocations are capable of boosting the photoconductivity. Strontium titanate single crystals are controllably deformed to generate a high density of ordered dislocations of two slip systems possessing different mesoscopic arrangements. For both slip systems, nanoscale conductive atomic force microscope investigations reveal a strong enhancement of the photoconductivity around the dislocation cores. Macroscopic in-plane measurements indicate that the two dislocation systems result in different global photoconductivity behavior despite the similar local enhancement. Depending on the arrangement, the global photoresponse can be increased by orders of magnitude. Additionally, indications for a bulk photovoltaic effect enabled by dislocation-surrounding strain fields are observed for the first time. This proves that dislocations in oxide semiconductors can be of large interest for tailoring photoelectric functionalities. Direct evidence that electronic transport is confined to the dislocation core points to a new emerging research field

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Using Decision Classification Criteria for Knowledge Acquisition and Transfer in Multi-Perspective Decision Making Processes

Abstrac

Enhanced Photoconductivity at Dislocations in SrTiO₃

Dislocations are 1D crystallographic line defects and are usually seen as detrimental to the functional properties of classic semiconductors. It is shown here that this not necessarily accounts for oxide semiconductors in which dislocations are capable of boosting the photoconductivity. Strontium titanate single crystals are controllably deformed to generate a high density of ordered dislocations of two slip systems possessing different mesoscopic arrangements. For both slip systems, nanoscale conductive atomic force microscope investigations reveal a strong enhancement of the photoconductivity around the dislocation cores. Macroscopic in-plane measurements indicate that the two dislocation systems result in different global photoconductivity behavior despite the similar local enhancement. Depending on the arrangement, the global photoresponse can be increased by orders of magnitude. Additionally, indications for a bulk photovoltaic effect enabled by dislocation-surrounding strain fields are observed for the first time. This proves that dislocations in oxide semiconductors can be of large interest for tailoring photoelectric functionalities. Direct evidence that electronic transport is confined to the dislocation core points to a new emerging research field

Enhanced Photoconductivity at Dislocations in SrTiO 3

Dislocations are 1D crystallographic line defects and are usually seen as detrimental to the functional properties of classic semiconductors. It is shown here that this not necessarily accounts for oxide semiconductors in which dislocations are capable of boosting the photoconductivity. Strontium titanate single crystals are controllably deformed to generate a high density of ordered dislocations of two slip systems possessing different mesoscopic arrangements. For both slip systems, nanoscale conductive atomic force microscope investigations reveal a strong enhancement of the photoconductivity around the dislocation cores. Macroscopic in‐plane measurements indicate that the two dislocation systems result in different global photoconductivity behavior despite the similar local enhancement. Depending on the arrangement, the global photoresponse can be increased by orders of magnitude. Additionally, indications for a bulk photovoltaic effect enabled by dislocation‐surrounding strain fields are observed for the first time. This proves that dislocations in oxide semiconductors can be of large interest for tailoring photoelectric functionalities. Direct evidence that electronic transport is confined to the dislocation core points to a new emerging research field

IgG Fab Glycans Hinder FcRn-Mediated Placental Transport

Abs can be glycosylated in both their Fc and Fab regions with marked effects on Ab function and binding. High levels of IgG Fab glycosylation are associated with malignant and autoimmune conditions, exemplified by rheumatoid arthritis and highly Fab-glycosylated (∼90%) anti-citrullinated protein Abs (ACPAs). Important properties of IgG, such as long half-life and placental transport, are facilitated by the human neonatal Fc receptor (hFcRn). Although it is known that glycosylation of Abs can affect binding to Fc receptors, little is known on the impact of IgG Fab glycosylation on hFcRn binding and transplacental transport. Therefore, we analyzed the interaction between hFcRn and IgG with and without Fab glycans in vitro with various methods as well as in vivo by studying placental transfer of Fab-glycosylated Abs from mothers to newborns. No effect of Fab glycosylation on IgG binding to hFcRn was found by surface plasmon resonance and hFcRn affinity chromatography. In contrast, studies in a cell membrane context revealed that Fab glycans negatively impacted IgG-hFcRn interaction. In line with this, we found that Fab-glycosylated IgGs were transported ∼20% less efficiently across the placenta. This appeared to be a general phenomenon, observed for ACPAs, non-ACPAs, as well as total IgG in rheumatoid arthritis patients and healthy controls. Our results suggest that, in a cellular context, Fab glycans inhibit IgG-hFcRn interaction and thus negatively affect the transplacental transfer of IgG. As Fab-glycosylated Abs are frequently associated with autoimmune and malignant disorders and may be potentially harmful, this might encompass a regulatory mechanism, limiting the half-life and transport of such Abs

IgG Fab Glycans Hinder FcRn-Mediated Placental Transport

Abs can be glycosylated in both their Fc and Fab regions with marked effects on Ab function and binding. High levels of IgG Fab glycosylation are associated with malignant and autoimmune conditions, exemplified by rheumatoid arthritis and highly Fab-glycosylated (~90%) anti-citrullinated protein Abs (ACPAs). Important properties of IgG, such as long half-life and placental transport, are facilitated by the human neonatal Fc receptor (hFcRn). Although it is known that glycosylation of Abs can affect binding to Fc receptors, little is known on the impact of IgG Fab glycosylation on hFcRn binding and transplacental transport. Therefore, we analyzed the interaction between hFcRn and IgG with and without Fab glycans in vitro with various methods as well as in vivo by studying placental transfer of Fab-glycosylated Abs from mothers to newborns. No effect of Fab glycosylation on IgG binding to hFcRn was found by surface plasmon resonance and hFcRn affinity chromatography. In contrast, studies in a cell membrane context revealed that Fab glycans negatively impacted IgG-hFcRn interaction. In line with this, we found that Fab-glycosylated IgGs were transported ~20% less efficiently across the placenta. This appeared to be a general phenomenon, observed for ACPAs, non-ACPAs, as well as total IgG in rheumatoid arthritis patients and healthy controls. Our results suggest that, in a cellular context, Fab glycans inhibit IgG-hFcRn interaction and thus negatively affect the transplacental transfer of IgG. As Fab-glycosylated Abs are frequently associated with autoimmune and malignant disorders and may be potentially harmful, this might encompass a regulatory mechanism, limiting the half-life and transport of such Abs