X- and gamma-ray studies of HESS J1731-347 coincident with a newly discovered SNR

In the survey of the Galactic plane conducted with H.E.S.S., many VHE gamma-ray sources were discovered for which no clear counterpart at other wavelengths could be identified. HESS J1731-347 initially belonged to this source class. Recently however, the new shell-type supernova remnant (SNR) G353.6-0.7 was discovered in radio data, positionally coinciding with the VHE source. We will present new X-ray observations that cover a fraction of the VHE source, revealing nonthermal emission that most likely can be interpreted as synchrotron emission from high-energy electrons. This, along with a larger H.E.S.S. data set which comprises more than twice the observation time used in the discovery paper, allows us to test whether the VHE source may indeed be attributed to shell-type emission from that new SNR. If true, this would make HESS J1731-347 a new object in the small but growing class of non-thermal shell-type supernova remnants with VHE emission.Comment: 4 pages, 5 figures, to appear in proceedings of the 31st ICRC, Lodz, Polan

Influencers and Communities in Social Networks

Integration of social media characteristics into an econometric framework requires modeling a high dimensional dynamic network with dimensions of parameter Θ typically much larger than the number of observations. To cope with this problem we introduce a new structural model which supposes that the network is driven by influencers. We additionally assume the community structure of the network, such that the users from the same community depend on the same influencers. An estimation procedure is proposed based on a greedy algorithm and LASSO. Through theoretical study and simulations, we show that the matrix parameter can be estimated even when the observed time interval is smaller than the size of the network. Using a novel dataset of 1069K messages from 30K users posted on the microblogging platform StockTwits during a 4-year period (01.2014-12.2018) and quantifying their opinions via natural language processing, we model their dynamic opinions network and further separate the network into communities. With a sparsity regularization, we are able to identify important nodes in the network

Observation of conformational exchange in cyclosporin in media of varying polarity by NMR spectroscopy

© Springer-Verlag Wien 2014. The molecule of peptide cyclosporin A experiences chemical exchange in polar solvents. In apolar media, such as chloroform or benzene, this transformation is suppressed, but still leads to formation of a small fraction of a minor conformer. To elucidate the nature of this phenomenon, the peptide was dissolved in mixed solvents chloroform–DMSO and water–DMSO. Analysis of 1H nuclear magnetic resonance and two-dimensional exchange spectroscopy spectra showed that the conformational exchange proceeds at a low rate of ~10-1 s-1 at the room temperature and involves passing over a high free energy barrier. Thus the situation resembles the exchange process in chloroform, associated with cis–trans isomerization of peptide bonds, but in the presence of DMSO transformation occurs at several sites independently, and the energy difference between arising conformers is small, 102–103 kJ/mol

Reduction of cholesterol and markers of oxidation in serum of hypercholestrolemic patients treated with lycosome formulation of simvastatin

Background: Use of microencapsulated HMG-CoA reductase inhibitors (statins) might be extremely helpful in the prevention of their side effects.Methods: 24 volunteers with hypercholesterolemia were given once daily 20 mg of lycosome-formulated Simvastatin fused with 7 mg lycopene (Lyco-Simvastatin) or the same amount of unmodified Simvastatin with no lycopene. Control patients received 7 mg of lycopene alone. Plasma lipids and oxidative markers were measured after 4 weeks of treatment.Results: Both formulations of Simvastatin, but not lycopene, caused a reduction in serum total cholesterol and LDL at the intermediate (end of 2nd week) and final (end of 4th week) points of interventional period. Notably, reduction of total cholesterol and LDL in the 4th week of the trial was more profound in patients treated with Lyco-Simvastatin versus unmodified Simvastatin (P<0.05). Patients treated with Lyco-Simvastatin showed a reduction in serum Apo B level, which was not observed in other groups. Lycopene treatment caused a modest but statistically significant decrease in serum triglyceride. However, the triglyceride-lowering effect of Simvastatin was more profound in the case of Lyco-Simvastatin treatment. Lycopene as well as unmodified Simvastatin gave a marginal reduction of Inflammatory Oxidative Damage. Remarkably, the combined formulation of Simvastatin and lycopene gave a significant reduction in the values for oxidative damage (reduction of median by 112.5 µM, P<0.05). Similar synergistic effect was observed when levels of oxidized LDL were analyzed.Conclusions: Lycosome-formulated microencapsulated Simvastatin has a better cholesterol-lowering and antioxidant capacity presumably due to enhanced bioavailability of the drug and synergism with lycopene

Spatial structures of tripeptides glycylglycyl-l-histidine and glycylglycyl-l-tyrosine based on residual dipolar couplings and quantum-chemical computations

A novel approach to the determination of the spatial structure of oligopeptides on the basis of an analysis of the residual dipolar couplings 1H-13C assisted by quantum-chemical computations with considering solvent effects is proposed to characterize the conformations of the tripeptides GlyGlyHis and GlyGlyTyr with significant folding of the latter to left-handed helix. © 2011 Mendeleev Communications. All rights reserved

Evaluation of solvent effects on parameters of conformational equilibrium on the basis of1H NMR data in the example of 1,3,2-dioxaphosphorinanes

1. By means of NMR, experimental data have been obtained on the dependence of conformational equilibrium parameters on the type of solvent. 2. The corrections arising as a consequence of the temperature dependence of the solvent permittivity e{open} are small in comparison with the generally accepted errors in determining the thermodynamic quantities of the conformational equilibrium. © 1985 Plenum Publishing Corporation

Principles for the correct description of intramolecular processes in dynamic NMR

Principles were proposed for the correct description of intramolecular processes using dynamic NMR (DNMR). The justification for these principles is illustrated for examples of the application of DNMR for the solution of such problems. © 1985 Plenum Publishing Corporation

Evidence of oligomerization of bovine insulin in solution given by NMR

© 2018, European Biophysical Societies' Association. The protein hormone insulin exists in several forms in nature, and a large number of modified sequences are used in pharmacy. They differ by physicochemical properties and efficiency of biological action. Pancreatic bovine insulin was studied in an acidic solution by nuclear magnetic resonance spectroscopy. 1H and 13C NMR signal assignment of backbone and side chains was made by analysis of a set of 2D spectra obtained on a sample with natural isotope abundance. The presence of certain secondary structure elements was revealed on a qualitative level based on nuclear Overhauser effect spectroscopy, which are similar to those observed in the crystal structure. The C-terminus of the B-chain possessed a remarkable flexibility. The molecule was shown to exist in exchange with oligomers based on its self-diffusion coefficient and correlation time measurements performed at different concentrations. Certain signals in the NOESY and HSQC spectra are consistent with the presence of minor conformers; this is an obstacle in simulating the molecular structure under the conditions used in the experiment

Peculiar outburst of A 0535+26 observed with INTEGRAL, RXTE and Suzaku

A normal outburst of the Be/X-ray binary system A0535+26 has taken place in August 2009. It is the fourth in a series of normal outbursts that have occured around the periastron passage of the source, but is unusual by starting at an earlier orbital phase and by presenting a peculiar double-peaked light curve. A first "flare" (lasting about 9 days from MJD 55043 on) reached a flux of 440 mCrab. The flux then decreased to less than 220 mCrab, and increased again reaching 440 mCrab around the periastron at MJD 55057. Target of Opportunity observations have been performed with INTEGRAL, RXTE and Suzaku. First results of these observations are presented, with special emphasis on the cyclotron lines present in the X-ray spectrum of the source, as well as in the pulse period and energy dependent pulse profiles of the source.Comment: 6 pages, Accepted for publication on PoS, Proceedings of "The Extreme sky: Sampling the Universe above 10 keV", held in Otranto (Italy) in October 200

Double magnetic resonance in MnCO3

© Kazan Federal University (KFU). Results of experiments on MnCO3 investigations by double magnetic resonance are presented. Additional mode of oscillation has been observed in a created Bose-Einstein condensation of magnons state in MnCO3. The properties of observed signals are similar to Goldstone modes