A Non-Mainstream Viewpoint on Apparent Superluminal Phenomena in AGN Jet

The group velocity of light in material around the AGN jet is acquiescently one (c as a unit), but this is only a hypothesis. Here, we re-derive apparent superluminal and Doppler formulas for the general case (it is assumed that the group velocity of light in the uniform and isotropic medium around a jet (a beaming model) is not necessarily equal to one, e.g., Araudo et al. (2010) thought that there may be dense clouds around AGN jet base), and show that the group velocity of light close to one could seriously affect apparent superluminal phenomena and Doppler effect in the AGN jet (when the viewing angle and Lorentz factor take some appropriate values).Comment: 4 pages, 2 figures, new version accepted for publication in Journal of Astrophysics and Astronom

An asymmetrical synchrotron model for knots in the 3C 273 jet

To interpret the emission of knots in the 3C 273 jet from radio to X-rays, we propose a synchrotron model in which, owing to the shock compression effect, the injection spectra from a shock into the upstream and downstream emission regions are asymmetric. Our model could well explain the spectral energy distributions of knots in the 3C 273 jet, and predictions regarding the knots spectra could be tested by future observations.Comment: 9 pages, 1 figure, 1 table, new version accepted for publication in Ap

Visible-light promoted atom transfer radical addition-elimination (ATRE) reaction for the synthesis of fluoroalkylated alkenes using DMA as electron-donor

Here, we describe a mild, catalyst-free and operationally-simple strategy for the direct fluoroalkylation of olefins driven by the photochemical activity of an electron donor-acceptor (EDA) complex between DMA and fluoroalkyl iodides. The significant advantages of this photochemical transformation are high efficiency, excellent functional group tolerance, and synthetic simplicity, thus providing a facile route for further application in pharmaceuticals and life sciences

Identification of Technical Journals by Image Processing Techniques

The emphasis of this study is put on developing an automatic approach to identifying a given unknown technical journal from its cover page. Since journal cover pages contain a great deal of information, determining the title of an unknown journal using optical character recognition techniques seems difficult. Comparing the layout structures of text blocks on the journal cover pages is an effective method for distinguishing one journal from the other. In order to achieve efficient layout-structure comparison, a left-to-right hidden Markov model (HMM) is used to represent the layout structure of text blocks for each kind of journal. Accordingly, title determination of an input unknown journal can be effectively achieved by comparing the layout structure of the unknown journal to each HMM in the database. Besides, from the layout structure of the best matched HMM, we can locate the text block of the issue date, which will be recognized by OCR techniques for accomplishing an automatic journal registration system. Experimental results show the feasibility of the proposed approach

Comparisons of housing price risks between first-time buyer and former owner-occupier markets in England

This study employs housing data from the nine main regions of England and from overall England to compare the volatility risks of housing prices for the first-time buyer (FTB) and former owneroccupier (FOO) markets. This study collects data from February 2012 to March 2020 to assess the volatility characteristics of housing prices in these two markets in each region of England. Additionally, the effect of interest rate shocks and the wealth effect of the stock market on these two markets are observed. The results reveal that for most regions, the FTB market has higher housing price volatility risks compared with the FOO market. Additionally, the FTB market is more easily affected by interest rate shocks and the wealth effect. In contrast to FOOs, FTBs are generally younger and less wealthy. If FTBs are facing a market with higher housing price risk, especially when the overall economy is affected by a shock (such as the European Debt Crisis or the COVID-19 pandemic), the response of the FTB housing market is greater; then the government must pay special attention when implementing policies that interfere with the market since these policies would particularly affect the welfare of FTBs

2-(2H-Tetra­zol-5-yl)pyridinium chloride

In the title compound, C6H6N5 +·Cl−, the pyridinium and tetra­zole rings are essentially coplanar. The pyridine N atoms are protonated. In the crystal structure, mol­ecules are connected via N—H⋯Cl, C—H⋯Cl, C—H⋯N and N—H⋯N hydrogen bonds into layers that are parallel to the (001) plane. There are two crystallographically independent mol­ecules in the asymmetric unit which are located on mirror planes