Timing and X-ray Spectral Features of Swift J1626.6-5156

In this paper, we extend timing analysis of Baykal et al. (2010) of \src using RXTE-PCA observations between MJD 53724 and MJD 55113 together with a Chandra-ACIS observation on MJD 54897 with a 20 ks exposure. We also present X-ray spectral analysis of these RXTE and Chandra observations. We find that the spin-up rate of the source is correlated with the X-ray flux. Using this correlation, we estimate the distance and surface magnetic field of the source as $\sim 15$kpc and $\sim 9\times 10^{11}$Gauss respectively. From the spectral analysis, we found that power law index increases and Hydrogen column density decreases with decreasing flux.Comment: Revised version; 12 pages, 4 figures, accepted for publication in MNRA

First results of observations of transient pulsar SAXJ2103.5+4545 with the INTEGRAL observatory

We present preliminary results of observations of X-ray pulsar SAX J2103.5+4545 with INTEGRAL observatory in Dec 2002. Maps of this sky region in energy bands 3-10, 15-40, 40-100 and 100-200 keV are presented. The source is significantly detected up to energies of $\sim100$ keV. The hard X-ray flux in the 15-100 energy band is variable, that could be connected with the orbital phase of the binary system. We roughly reconstructed the source spectrum using its comparison to that of Crab nebula. It is shown that the parameters of the source spectrum in 18-150 keV energy range are compatible with that obtained earlier by RXTE observatoryComment: 5 pages, 4 figures, accepted for publication in the Astronomy Letter

X-ray Spectral Evolution of Her X-1 in a Low State and the Following Short High State

We analyzed spectral variations of $\sim 8.5$ days long RXTE monitoring observations of Her X-1 in December 2001. This set of observations enables, for the first time, frequent continuous monitoring (111 pointings in $\sim 8.5$ days) of the source with RXTE including $\sim 1.7$ days long low state part and the following $\sim 6.8$ days long short high state part. We used absorbed power law model with iron line energy complex modeled as a Gaussian to fit both the 3-60 keV PCA-HEXTE overall short high state spectrum and 3-20 keV individual PCA spectra. Additional partial cold absorber model was used for both cases. Using 3-20 keV individual PCA spectra, absorption in anomalous dips and preeclipse dips in short high state were compared. Decreasing ratio of unabsorbed flux to absorbed flux with increasing unabsorbed flux in anomalous and preeclipse dips was interpreted as an evidence of the fact that the regions causing opaque obscuration and soft absorption are not geometrically far away from each other. Higher iron line peak energies in low state and short high state ($\sim 6.6-6.9$ keV) were interpreted as a clue of the presence of iron line components other than K$\alpha$ emission line.Comment: 11 pages, 4 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS

Recent Spin Rate Measurements of 4U 1907+09

In this study, X-ray spectral and pulse timing analysis of the high mass X-ray binary (HMXB) pulsar 4U 1907+09, based on the observations with RXTE are presented. Spin rate measurements indicate a new spin-down episode with a rate close to the previous steady spin-down rate. Orbital phase resolved spectroscopy reveals that the Hydrogen column density varies through the orbit reaching to its maximum value just after periastron. A slight spectral softening with increasing luminosity is also observed.Comment: 3 pages, 1 figure, Conference proceeding of "Astrophysics of Neutron Stars 2010 -- a conference in honor of M. Ali Alpar", 2-6 August 2010, Cesme, Izmir, Turke

The influence of post-fixation on visualising vimentin in the retina using immunofluorescence method

Background: Post-fixation of sections is especially required for cryostat sections of fresh frozen tissues. Vimentin is an intermediate filament in both fibrillary and non-fibrillary form, expressed in Müller’s cells and astrocytes of the retina. Our aim was to determine the best post-fixation method for visualising vimentin in archival mouse eyes. Materials and methods: We used an archival mouse eye, slightly pre-fixed with paraformaldehyde and stored at –80°C for 4 years. We tried three fixatives (pa­raformaldehyde [PFA], alcohol/acetic acid [AAA] and methanol) for post-fixation of eye sections. Results: We showed that post-fixation alters the labelling properties of vimentin expressed in the retina. In the sections with no post-fixation, vimentin positivity was observed in and around the nuclei in non-fibrillary form. In PFA post-fixed sections, the vimentin in the retina was not observed as fibrils. Positivity was observed in the nuclei and in perinuclear regions of the cells. In AAA post-fixed sections, positive labelling was observed around the nuclei as fibrils. In methanol post-fixed sections, labelling was observed around the nuclei as fibrils. Conclusions: We conclude that post-fixation with AAA is more convenient for immunofluorescent labelling of vimentin in the retina for slightly PFA pre-fixed and long-term stored retina. (Folia Morphol 2018; 77, 2: 246–252