118 research outputs found
Phase correlation of laser waves with arbitrary frequency spacing
The theoretically predicted correlation of laser phase fluctuations in
Lambda-type interaction schemes is experimentally demonstrated. We show, that
the mechanism of correlation in a Lambda scheme is restricted to high frequency
noise components, whereas in a double- scheme, due to the laser phase
locking in closed-loop interaction, it extends to all noise frequencies. In
this case the correlation is weakly sensitive to coherence losses. Thus the
double-Lambda scheme can be used to correlate e.m. fields with carrier
frequency differences beyond the GHz regime.Comment: 4 pages, 4 figure
The two phases of core formation : orbital evolution in the centres of ellipticals with supermassive black hole binaries
The flat stellar density cores of massive elliptical galaxies form rapidly due to sinking supermassive black holes (SMBHs) in gas-poor galaxy mergers. After the SMBHs form a bound binary, gravitational slingshot interactions with nearby stars drive the core regions towards a tangentially biased stellar velocity distribution. We use collisionless galaxy merger simulations with accurate collisional orbit integration around the central SMBHs to demonstrate that the removal of stars from the centre by slingshot kicks accounts for the entire change in velocity anisotropy. The rate of strong (unbinding) kicks is constant over several hundred Myr at similar to 3 M-circle dot yr(-1) for our most massive SMBII binary (M-BH = 1.7 x 10(10) M-circle dot). Using a frequency-based orbit classification scheme (box, x-tube, z-tube, rosette), we demonstrate that slingshot kicks mostly affect box orbits with small pericentre distances, leading to a velocity anisotropy of beta less than or similar to -0.6 within several hundred Myr as observed in massive ellipticals with large cores. We show how different SMBH masses affect the orbital structure of the merger remnants and present a kinematic tomography connecting orbit families to integral field kinematic features. Our direct orbit classification agrees remarkably well with a modern triaxial Schwarzschild analysis applied to simulated mock kinematic maps.Peer reviewe
Kinetic model of II-VI(001) semiconductor surfaces: Growth rates in atomic layer epitaxy
We present a zinc-blende lattice gas model of II-VI(001) surfaces, which is
investigated by means of Kinetic Monte Carlo (KMC) simulations. Anisotropic
effective interactions between surface metal atoms allow for the description
of, e.g., the sublimation of CdTe(001), including the reconstruction of
Cd-terminated surfaces and its dependence on the substrate temperature T. Our
model also includes Te-dimerization and the potential presence of excess Te in
a reservoir of weakly bound atoms at the surface. We study the self-regulation
of atomic layer epitaxy (ALE) and demonstrate how the interplay of the
reservoir occupation with the surface kinetics results in two different
regimes: at high T the growth rate is limited to 0.5 layers per ALE cycle,
whereas at low enough T each cycle adds a complete layer of CdTe. The
transition between the two regimes occurs at a characteristic temperature and
its dependence on external parameters is studied. Comparing the temperature
dependence of the ALE growth rate in our model with experimental results for
CdTe we find qualitative agreement.Comment: 9 pages (REVTeX), 8 figures (EPS). Content revised, references added,
typos correcte
Reproducibility of the peritoneal regression grading score for assessment of response to therapy in peritoneal metastasis.
The four-tiered peritoneal regression grading score (PRGS) assesses the response to chemotherapy in peritoneal metastasis (PM). The PRGS is used, for example, to assess the response to pressurised intraperitoneal aerosol chemotherapy (PIPAC). However, the reproducibility of the PRGS is currently unknown. We aimed to evaluate the inter- and intraobserver variability of the PRGS.
Thirty-three patients who underwent at least three PIPAC treatments as part of the PIPAC-OPC1 or PIPAC-OPC2 clinical trials at Odense University Hospital, Denmark, were included. Prior to each therapy cycle, peritoneal quadrant biopsies were obtained and three haematoxylin and eosin (H&E)-stained step sections were scanned and uploaded to a pseudonymised web library. For determining interobserver variability, eight pathologists assessed the PRGS for each quadrant biopsy, and Krippendorff's alpha and intraclass correlation coefficients (ICCs) were calculated. For determining intraobserver variability, three pathologists repeated their own assessments and Cohen's kappa and ICCs were calculated. A total of 331 peritoneal biopsies were analysed. Interobserver variability for PRGS of each biopsy and for the mean and maximum PRGS per biopsy set was moderate to good/substantial. The intraobserver variability for PRGS of each biopsy and for the mean and maximum PRGS per biopsy set was good to excellent/almost perfect.
Our data support the PRGS as a reproducible and useful tool to assess response to intraperitoneal chemotherapy in PM. Future studies should evaluate the prognostic and predictive role of the PRGS
Role of immunohistochemistry for interobserver agreement of Peritoneal Regression Grading Score in peritoneal metastasis.
Pressurized intraperitoneal aerosol chemotherapy (PIPAC)-directed therapy is a new treatment option for peritoneal metastasis (PM). The 4-tiered Peritoneal Regression Grading Score (PRGS) has been proposed for assessment of histological treatment response. We aimed to evaluate the effect of immunohistochemistry (IHC) on interobserver agreement of the PRGS. Hematoxylin and eosin (H&E)-stained and IHC-stained slides (n = 662) from 331 peritoneal quadrant biopsies (QBs) taken prior to 99 PIPAC procedures performed on 33 patients were digitalized and uploaded to a web library. Eight raters (five consultants and three residents) assessed the PRGS, and Krippendorff's alpha coefficients (α) were calculated. Results (IHC-PRGS) were compared with data published in 2019, using H&E-stained slides only (H&E-PRGS). Overall, agreement for IHC-PRGS was substantial to almost perfect. Agreement (all raters) regarding single QBs after treatment was substantial for IHC-PRGS (α = 0.69, 95% confidence interval [CI] = 0.66-0.72) and moderate for H&E-PRGS (α = 0.60, 95% CI = 0.56-0.64). Agreement (all raters) regarding the mean PRGS per QB set after treatment was higher for IHC-PRGS (α = 0.78, 95% CI = 0.73-0.83) than for H&E-PRGS (α = 0.71, 95% CI = 0.64-0.78). Among residents, agreement was almost perfect for IHC-PRGS and substantial for H&E-PRGS. Agreement (all raters) regarding maximum PRGS per QB set after treatment was substantial for IHC-PRGS (α = 0.61, 95% CI = 0.54-0.68) and moderate for H&E-PRGS (α = 0.60, 95% CI = 0.53-0.66). Among residents, agreement was substantial for IHC-PRGS (α = 0.66, 95% CI = 0.57-0.75) and moderate for H&E-PRGS (α = 0.55, 95% CI = 0.45-0.64). Additional IHC seems to improve the interobserver agreement of PRGS, particularly between less experienced raters
Lack of complex I is associated with oncocytic thyroid tumours
Oncocytic tumours are characterised by hyperproliferation of mitochondria. We immunohistochemically analysed all enzymes of the oxidative phosphorylation system in 19 oncocytic thyroid tumours. A specific lack of complex I was detected, which was expressed at <5% of the level determined in surrounding non-cancerous tissue
Understanding the decomposition reaction mechanism of chrysanthemic acid: a computational study
<p>Abstract</p> <p>Background</p> <p>Chrysanthemic acid (<b>CHA</b>) is a major product from the photodecomposition of pyrethrin which is an important class of pesticide compounds.</p> <p>In the following paper, Hybrid density functional theory (DFT) calculations of the potential energy surface (PES) for three possible channels decomposition of chrysanthemic acid <b>(</b>cis-trans isomerization, rearrangement and fragmentation) have been carried at the B3LYP/6-311+G** level of theory. DFT was employed to optimize the geometry parameters of the reactants, transition states, intermediates and products based on detailed potential energy surfaces (PES).</p> <p>Results</p> <p>Our results suggest that all three pathways of <b>CHA </b>are endothermic. DFT calculations revealed that the activation barriers for cis-trans isomerization are low, leading to a thermodynamically favorable process than other two pathways. We also investigated the solvent effect on the PES using the polarizable continuum model (PCM). In addition, time-dependent density functional theory (TDDFT) calculations showed that these reactions occur in the ground state rather than in an excited state.</p> <p>Conclusion</p> <p>The rearrangement process seems to be more favorable than the decomposition of <b>CHA </b>to carbene formation. The solvent effect calculations indicated no changes in the shape of the PES with three continua (water, ethanol and cyclohexane), although the solvents tend to stabilize all of the species.</p
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