SN 2018gjx reveals that some SNe Ibn are SNe IIb exploding in dense circumstellar material

ABSTRACT We present the data and analysis of SN 2018gjx, an unusual low-luminosity transient with three distinct spectroscopic phases. Phase I shows a hot blue spectrum with signatures of ionized circumstellar material (CSM), Phase II has the appearance of broad SN features, consistent with those seen in a Type IIb supernova at maximum light, and Phase III is that of a supernova interacting with helium-rich CSM, similar to a Type Ibn supernova. This event provides an apparently rare opportunity to view the inner workings of an interacting supernova. The observed properties can be explained by the explosion of a star in an aspherical CSM. The initial light is emitted from an extended CSM (∼4000 R⊙), which ionizes the exterior unshocked material. Some days after, the SN photosphere envelops this region, leading to the appearance of a SN IIb. Over time, the photosphere recedes in velocity space, revealing interaction between the supernova ejecta and the CSM that partially obscures the supernova nebular phase. Modelling of the initial spectrum reveals a surface composition consistent with compact H-deficient Wolf–Rayet and Luminous Blue Variable (LBV) stars. Such configurations may not be unusual, with SNe IIb being known to have signs of interaction so at least some SNe IIb and SNe Ibn may be the same phenomena viewed from different angles, or possibly with differing CSM configurations.

The Spectrum of FANCM Protein Truncating Variants in European Breast Cancer Cases

Germline protein truncating variants (PTVs) in the FANCM gene have been associated with a 2–4-fold increased breast cancer risk in case-control studies conducted in different European populations. However, the distribution and the frequency of FANCM PTVs in Europe have never been investigated. In the present study, we collected the data of 114 European female breast cancer cases with FANCM PTVs ascertained in 20 centers from 13 European countries. We identified 27 different FANCM PTVs. The p.Gln1701* PTV is the most common PTV in Northern Europe with a maximum frequency in Finland and a lower relative frequency in Southern Europe. On the contrary, p.Arg1931* seems to be the most common PTV in Southern Europe. We also showed that p.Arg658*, the third most common PTV, is more frequent in Central Europe, and p.Gln498Thrfs*7 is probably a founder variant from Lithuania. Of the 23 rare or unique FANCM PTVs, 15 have not been previously reported. We provide here the initial spectrum of FANCM PTVs in European breast cancer cases.

Near-field spectrum retrieving through non-degenerate coupling emission

We present a scheme to retrieve the initial spectrum of probe molecules in the near field. This is achieved by replacing conventional glass substrates with a hybrid mode photonics chip to create rich and persistent mode distributions and by observing the far-field scattering pattern. The manner of coupling from near field to far field is confirmed by the calculated dependence of the coupled emission signal on the unique material properties. By using an optimization algorithm to retrieve the intensity ratio of near-field optical signals in each frequency band gradually without the need for complicated instruments and time-consuming acquisition processes, our method can achieve broadband non-distortion spectral analysis in an enhanced optical antenna by selecting substrate parameters.

An exact solution of cosmic ray modulation problem in a stationary composite heliosphere model

ABSTRACT A new theoretical approach to describe the physical processes of energy particle propagation is proposed. This approach is based on the analytically iterative method for solving closed cosmic ray (CR) modulation problems, which was proposed by Shakhov and Kolesnyk. First, we have applied the approach on a simple model of the heliosphere, wherein the diffusion coefficients κ for each region of CR modulation are constants. This approach produced a very good matching of the obtained solution and also provided a numerical solution and an analytical solution. Finally, a modern problem of CR modulation in a stationary composite model of the heliosphere was considered. This model includes an environment that contains adjacent spherically symmetric regions with different modes of propagation of the solar wind (SW) speed for each layer. The CR scattering is due to different factors for each layer of the environment, as characterized by relevant κ values that simultaneously have dependence on the momentum of the particle p and the particle speed $\upsilon$, i.e. $\kappa \propto p\upsilon$. The local interstellar spectra (LISs) are given by a power-law unmodulated spectrum with the slope of the initial spectrum α, i.e. LIS ∝ p−α. An exact solution of the problem of CR modulation for low-energy particles and high-energy particles was first derived and qualitatively compared against the Voyager 1 data.

Analysis of the Relationship Between Spectral and Color Uncertainty

An approach is proposed for an approximate estimate of the relation between the uncertainties of spectral and color measurements. The approach is based on replacing the entire diversity of the spectra with simple models: a constant over all wavelengths, a pronounced peak, a sharp decrease and a sharp increase. The Monte-Carlo method was used for calculations. Small distortions were introduced to the model spectra at each wavelength, the standard deviation of these distortions was calculated, after which the chromaticity coordinates were calculated in the system (x, y, Y). The value of Y, as related to light measurements, was not further analyzed. The standard deviation of the distances between the chromaticity coordinates of the initial spectrum and the chromaticity coordinates of the distorted spectra in space (x, y) was used as a measure of the uncertainty of color measurements. The ratio of these standard devia­tions was considered to be a link between the uncertainties of the spectral and color measurements. The influence of the uncertainties of the spectral measurements, the effect of the spectral width of the model spectra in the form of a peak, a sharp decrease and a sharp increase on the axis of the wavelengths were analyzed. The ran­ges of the corresponding values are chosen taking into account the valid documents and the most common spectra. The influence of a stan­dard illuminator selected was considered: all calculations were carried out for both type A and D65 sources. The results of the calculations are provided in the form of graphs, which allow one to approximately determine the required level of accuracy of the spectral equipment before the measurements, in order to provide the necessary uncertainty of chromaticity measurements. The analysis of the results obtained.

A spatio-kinematic model for jets in post-AGB stars,

Aims. We aim to determine the geometry, density gradient, and velocity structure of jets in post-asymptotic giant branch (post-AGB) binaries. Methods. Our high cadence time series of high-resolution optical spectra of jet-creating post-AGB binary systems provide us with a unique tomography of the jet. We determine the spatio-kinematic structure of the jets based on these data by fitting the synthetic spectral line profiles created by our model to the observed, orbital phase-resolved, Hα-line profiles of these systems. The fitting routine is provided with an initial spectrum and is allowed to test three configurations, derived from three specific jet launching models: a stellar jet launched by the star, an X-wind, and a disk wind configuration. We apply a Markov-chain Monte Carlo routine in order to fit our model to the observations. Our fitting code is tested on the post-AGB binary IRAS 19135+3937. Results. We find that a model using the stellar jet configuration gives a marginally better fit to our observations. The jet has a wide half-opening angle of about 76° and reaches velocities up to 870 km s−1. Conclusions. Our methodology is successful in determining some parameters for jets in post-AGB binaries. The model for IRAS 19135+3937 includes a transparent, low density inner region (for a half-opening angle < 40°). The source feeding the accretion disk around the companion is most likely the circumbinary disk. We will apply this jet fitting routine to other jet-creating post-AGB stars in order to provide a more complete description of these objects.

Impact of secondary particles on microdistribution of deposited dose in biological tissue in the presence of gold and gadolinium nanoparticles under photon beam irradiation

It is experimentally proven that nanoparticles of high-Z materials can be used as radiosensitizers for photon beam therapy. In the authors’ opinion, data available as of today on the impact of secondary particles (electrons, photons and positrons generated in biological tissue by penetrating beam of primary photons) on the distribution of deposited dose during photon beam therapy in the presence of nanoparticles, are insufficient. Investigation of this impact constituted the main goal of this work. Two-stage simulation was performed using Geant4 platform. During the first stage a layer of biological tissue (water) was irradiated by monoenergetic photon sources with energies ranging from 10 keV to 6 MeV. As the result of this modeling spectra of electrons, photons and positrons were obtained at the depth of 5 cm. During the second stage the obtained photon spectra were used to irradiate gold, gadolinium and water nanoparticles. Radial distributions of energy deposited around nanoparticles were obtained as the result of this modeling. Radial DEF (Dose Enhancement Factor) values around nanoparticles of gold and gadolinium positioned in water at the depth of 5 cm were obtained after processing the collected data. Contributions from primary photons and secondary particles (electrons, photons and positrons generated in the layer of water with 5-cm thickness by the penetrating beam of primary photons) in the additional dose deposited around the nanoparticles were calculated as well. It was demonstrated that layer of biological tissue placed between the source of photons and nanoparticles considerably changes the initial spectrum of photons and this change is significant in the analysis of mechanism of radiosensitization of biological tissues by nanoparticles for all energies of photon sources (up to 6 MeV). It was established that interaction of electrons and positrons with nanoparticles does not lead to significant increase of additional dose in the vicinity of their surfaces and can be most likely excluded from consideration in the analysis of radiosensitization mechanism of nanoparticles.

The Effect of a Dominant Initial Single Mode on the Kelvin–Helmholtz Instability Evolution: New Insights on Previous Experimental Results

This paper brings new insights on an experiment, measuring the Kelvin–Helmholtz (KH) instability evolution, performed on the OMEGA-60 laser facility. Experimental radiographs show that the initial seed perturbations in the experiment are of multimode spectrum with a dominant single-mode of 16 μm wavelength. In single-mode-dominated KH instability flows, the mixing zone (MZ) width saturates to a constant value comparable to the wavelength. However, the experimental MZ width at late times has exceeded 100 μm, an order of magnitude larger. In this work, we use numerical simulations and a statistical model in order to investigate the vortex dynamics of the KH instability for the experimental initial spectrum. We conclude that the KH instability evolution in the experiment is dominated by multimode, vortex-merger dynamics, overcoming the dominant initial mode.

A Comparison of Modeling Techniques for Polydispersed Droplet Spectra in Steam Turbines

Within steam turbine flows, condensation phenomena give rise to complex droplet spectra that can span more than two orders of magnitude in size. To predict the behavior of the two-phase flow and the resulting losses, the interactions between the vapor phase and droplets of all sizes must be accurately calculated. The estimation of thermodynamic losses and droplet deposition rates, in particular, depends on the size range and shape of the droplet spectrum. These calculations become computationally burdensome when a large number of droplet groups are present, and it is therefore advantageous to capture the complete droplet spectrum in a compressed form. This paper compares several methods for reducing the complexity of the droplet spectrum: a single representative droplet size (equivalent monodispersion), the moment method (including various growth rate approximations), the quadrature method of moments (QMOM), and spectrum pruning. In spectrum pruning, droplet groups are individually nucleated, but their number is subsequently reduced by combining groups together in a manner that preserves droplet number, wetness fraction, and the shape of the initial spectrum. The various techniques are compared within a Lagrangian framework by tracking the two-phase behavior along predefined pressure–time trajectories. Primary and secondary nucleation, droplet evaporation, and a representative turbomachinery case are modeled. The calculations are compared in terms of speed, accuracy, and robustness. It is shown that both the moment methods and spectrum pruning provide an appreciable improvement in accuracy over the use of an “equivalent” monodispersion without compromising calculation speed. Although all the examined methods are adequate for primary nucleation and droplet growth calculations, spectrum pruning and the QMOM are most accurate over the range of conditions considered.

Large-Scale Errors and Mesoscale Predictability in Pacific Northwest Snowstorms

The predictability of lowland snow in the Puget Sound region of the Pacific Northwest is explored by analyzing the spread in 100-member ensemble simulations for two events from December 2008. Sensitivities to the microphysical and boundary layer parameterizations in these simulations are minimized by estimating the likely precipitation type from the forecast 850-hPa temperatures and the established rain–snow climatology. Results suggest that the ensemble spread in events such as these, which were triggered by amplifying short waves, may develop a significant fraction of both rain-likely members and snow-likely members at forecast lead times as short as 36 h. The perturbation kinetic energy of the ensemble members about the ensemble mean () is not maximized at small scales. Instead, the power in the initial spectrum of produced by the authors’ ensemble Kalman filter (EnKF) data assimilation cycle increases with increasing horizontal scale. The power in subsequently grows with time, while maintaining approximately the same spectral shape. There is no evidence of small-scale perturbations developing rapidly and transferring their influence upscale. Instead, the large-scale perturbations appear to grow more rapidly during the first 12 h than those at the smallest resolved scales.