Origin of second-harmonic generation in the incommensurate phase of K2SeO4

We show that a ferroelectric phase transition takes place in the incommensurate phase of the K2SeO4 crystal. The ferroelectric character of the IC phase explains the second-harmonic generation observed in the corresponding temperature range.Comment: 5 pages, 1 figur

Self-Adjointness of Generalized MIC-Kepler System

We have studied the self-adjointness of generalized MIC-Kepler Hamiltonian, obtained from the formally self-adjoint generalized MIC-Kepler Hamiltonian. We have shown that for \tilde l=0, the system admits a 1-parameter family of self-adjoint extensions and for \tilde l \neq 0 but \tilde l <{1/2}, it has also a 1-parameter family of self-adjoint extensions.Comment: 11 pages, Latex, no figur

Measurement of Dielectric Suppression of Bremsstrahlung

In 1953, Ter-Mikaelian predicted that the bremsstrahlung of low energy photons in a medium is suppressed because of interactions between the produced photon and the electrons in the medium. This suppression occurs because the emission takes place over on a long distance scale, allowing for destructive interference between different instantaneous photon emission amplitudes. We present here measurements of bremsstrahlung cross sections of 200 keV to 20 MeV photons produced by 8 and 25 GeV electrons in carbon and gold targets. Our data shows that dielectric suppression occurs at the predicted level, reducing the cross section up to 75 percent in our data.Comment: 11 pages, format is postscript file, gzip-ed, uuencode-e

Effect of CPAP therapy on left atrial remodeling in patients with paroxysmal atrial fibrillation and obstructive sleep apnea undergoing pulmonary vein isolation

Aim. To study the isolated effect of obstructive sleep apnea (OSA) on left atrial (LA) remodeling in patients with paroxysmal atrial fibrillation (AF) who underwent pulmonary vein (PV) ablation and concomitant severe and moderate OSA.Material and methods. A subanalysis of echocardiographic data was performed in 50 patients with paroxysmal AF and moderate/severe OSA who underwent PV isolation and were followed up for 12 months (main group, 33; control group, 17). The clinical efficacy of catheter ablation was assessed after the end of the threemonth blind period. The following echocardiographic parameters were included in the subanalysis: anterior-posterior LA dimension, LA volume, LA volume index (LAVI), and pulmonary artery systolic pressure (PASP).Results. After 12 months, the control group showed a significant increase in the anterior-posterior LA dimension (40,5 (40-42) mm vs 42 (40-45) mm, p=0,037), LA volume (68,5 (58-74,5) ml vs 69 (63-89) ml, p=0,006), LAVI (35,0 (29-37) ml/m2 vs 35,5 (32-41,5) ml/m2, p=0,005) and PASP (27 (25-30) vs 30 (29-33), p=0,004). Intragroup analysis of patients not receiving continuous positive airway pressure (CPAP) therapy and without recurrent AF did not reveal significant changes in LA size (anterior-posterior LA dimension — 40 (40-42) mm vs 40 (40- 41) mm, p=0,317; LA volume — 63 (58-71) ml vs 64 (61-69) ml, p=0,509; LAVI — 32 (29-36) ml/m2 vs 33 (31-34) ml2, p=0,509).Conclusion. In patients with paroxysmal AF and concomitant moderate to severe OSA who underwent AF catheter treatment, the absence of CPAP therapy is not associated with a significant increase in the linear and volume LA dimensions in the absence of AF recurrence

Bremsstrahlung Suppression due to the LPM and Dielectric Effects in a Variety of Materials

The cross section for bremsstrahlung from highly relativistic particles is suppressed due to interference caused by multiple scattering in dense media, and due to photon interactions with the electrons in all materials. We present here a detailed study of bremsstrahlung production of 200 keV to 500 MeV photons from 8 and 25 GeV electrons traversing a variety of target materials. For most targets, we observe the expected suppressions to a good accuracy. We observe that finite thickness effects are important for thin targets.Comment: 52 pages, 13 figures (incorporated in the revtex LaTeX file

Comprehensive mapping of tissue cell architecture via integrated single cell and spatial transcriptomics

elocation-id: 2020.11.15.378125elocation-id: 2020.11.15.378125The spatial organization of cell types in tissues fundamentally shapes cellular interactions and function, but the high-throughput spatial mapping of complex tissues remains a challenge. We present сell2location, a principled and versatile Bayesian model that integrates single-cell and spatial transcriptomics to map cell types in situ in a comprehensive manner. We show that сell2location outperforms existing tools in accuracy and comprehensiveness and we demonstrate its utility by mapping two complex tissues. In the mouse brain, we use a new paired single nucleus and spatial RNA-sequencing dataset to map dozens of cell types and identify tissue regions in an automated manner. We discover novel regional astrocyte subtypes including fine subpopulations in the thalamus and hypothalamus. In the human lymph node, we resolve spatially interlaced immune cell states and identify co-located groups of cells underlying tissue organisation. We spatially map a rare pre-germinal centre B-cell population and predict putative cellular interactions relevant to the interferon response. Collectively our results demonstrate how сell2location can serve as a versatile first-line analysis tool to map tissue architectures in a high-throughput manner.Competing Interest StatementThe authors have declared no competing interest

Coordination as a function of skill level in the gymnastics longswing

The purpose of this study was to investigate the nature of inter-joint coordination at different levels of skilled performance to: (1) distinguish learners who were successful versus unsuccessful in terms of their task performance; (2) investigate the pathways of change during the learning of a new coordination pattern and (3) examine how the learner’s coordination patterns relate to those of experts in the longswing gymnastics skill. Continuous relative phase of hip and shoulder joint motions was examined for longswings performed by two groups of novices, successful (n = 4) and unsuccessful (n = 4) over five practice sessions, and two expert gymnasts. Principal component analysis showed that during longswing positions where least continuous relative phase variability occurred for expert gymnasts, high variability distinguished the successful from the unsuccessful novice group. Continuous relative phase profiles of successful novices became more out-of-phase over practice and less similar to the closely in-phase coupling of the expert gymnasts. Collectively, the findings support the proposition that at the level in inter-joint coordination a technique emerges that facilitates successful performance but is not more like an expert’s movement coordination. This finding questions the appropriateness of inferring development towards a “gold champion” movement coordination

Anodal Block in Evaluation of Nerve Conduction Changes in Anesthetized Rats: Preclinical Non-Randomized Experimental Study

Background. There is currently no gold standard for functional assessment of nerve regeneration. Different researchers use various methods to assess the functionality of the regenerated nerve directly and indirectly. Indirect methods have the advantage of being minimally invasive, and the benefit of direct methods is recording the signal directly in the nerve.Objectives. To identify significant parameters of neurogram changes in the sciatic nerve in an anaesthetized rat when the anode block is applied and to evaluate neurography as a method for functional assessment of nerve regeneration.Methods. A series of experiments was performed on 10 anaesthetized rats. A DC anode was placed on the exposed sciatic nerve, more proximal and more distal to the recording electrodes, and a common cathode in the form of a needle was introduced into one of the forelimbs. Needle nichrome electrodes were introduced into the nerve using a manipulator. An original neurogram and a neurogram against anode activation were recorded by closing the DC circuit of different voltages to block the afferent signal, efferent signal and afferent and efferent signals simultaneously.Results. When the anodal block of different voltages was applied to the afferent signal, efferent signal, and afferent and efferent signals simultaneously in all 10 experiments, the frequency-amplitude characteristics of the neurogram changed significantly as compared to the original neurogram. The amplitude of the neurogram increased considerably, while the frequency decreased, though not so dramatically. The changes in amplitude and frequency parameters were revealed to depend on the voltage value. In most cases, this relationship was directly proportional to the amplitude and inversely proportional to the frequency.Conclusion. Considering the nature of the dynamics of the neurogram when exposed to the anodal block, the most significant parameter of its change is the amplitude. Changes in nerve fibre composition during its regeneration after damage cause changes in afferent and efferent signals, which is likely to be displayed in the neurogram as compared to the initial state. Thus, the anodal block can be used as a model of nerve damage, and the analysis of the dynamics of neurogram parameters — as a method for functional assessment of nerve regeneration

The regulatory subunit of PKA-I remains partially structured and undergoes β-aggregation upon thermal denaturation

Background: The regulatory subunit (R) of cAMP-dependent protein kinase (PKA) is a modular flexible protein that responds with large conformational changes to the binding of the effector cAMP. Considering its highly dynamic nature, the protein is rather stable. We studied the thermal denaturation of full-length RIα and a truncated RIα(92-381) that contains the tandem cyclic nucleotide binding (CNB) domains A and B. Methodology/Principal Findings: As revealed by circular dichroism (CD) and differential scanning calorimetry, both RIα proteins contain significant residual structure in the heat-denatured state. As evidenced by CD, the predominantly α-helical spectrum at 25°C with double negative peaks at 209 and 222 nm changes to a spectrum with a single negative peak at 212-216 nm, characteristic of β-structure. A similar α→β transition occurs at higher temperature in the presence of cAMP. Thioflavin T fluorescence and atomic force microscopy studies support the notion that the structural transition is associated with cross-β-intermolecular aggregation and formation of non-fibrillar oligomers. Conclusions/Significance: Thermal denaturation of RIα leads to partial loss of native packing with exposure of aggregation-prone motifs, such as the B' helices in the phosphate-binding cassettes of both CNB domains. The topology of the β-sandwiches in these domains favors inter-molecular β-aggregation, which is suppressed in the ligand-bound states of RIα under physiological conditions. Moreover, our results reveal that the CNB domains persist as structural cores through heat-denaturation. © 2011 Dao et al

Comparison of the results of ⁸⁵Kr transport modeling with the ACURATE field experiment data

© 2017, Allerton Press, Inc.Currently the Nuclear Safety Institute of the Russian Academy of Sciences (NSI RAS) jointly with the Hydrometcenter of Russia is developing the system for forecasting the transfer of radio-active substances in the atmosphere in case of radiation accidents at Russian nuclear power plants. The operation of the system is based on the numerical hydrodynamic model which allows forecasting meteorological parameters and is coupled with the mesoscale dispersion model of the transfer ofradioactive substances in the atmosphere. The results are presented of 85Kr transport modeling under the conditions of the ACURATE experiment with three transport models: FLEXPART, HYSPLIT, and the model from the NOSTRADAMUS software package. It is demonstrated that all three Lagrangian models can give a qualitative description of concentration fields from the ACURATE experiment with the best value of the RANK metric (2.5) based on three statistics