X-ray outbursts of AXPs and SGRs

We show that the X‐ray enhancement light curves of transient AXP∕SGRs can be reproduced by the active fallback disk model. We solve the diffusion equation for the relaxation of a disk that has been pushed back by a soft gamma‐ray burst. Our preliminary results indicate that a critical temperature around 1500 K leads to a thermal‐viscous instability in the fallback disks of all AXP∕SGRs. The effect of the instability on the light curves are different for transient and persistent sources due to different pre‐burst disk conditions in these systems

On the evolution of young neutron stars with fallback disks

In the last decades, developments in observational techniques led to the discovery of new young isolated neutron star populations. Despite distinguishing differences, these young systems also have striking similarities, which suggest possible evolutionary links between them. The emergence of these different populations is likely to be due to their different initial conditions. Understanding the nature of these neutron stars in a single coherent picture requires a detailed investigation of individual properties of the sources that belong to different classes. The properties and emergence of these young neutron stars as distinct populations could be explained if absence, presence and properties of fallback disks are included in the initial conditions in addition to magnetic moment and initial period (Alpar 2001). Pursuing this idea, we investigate the properties of AXP/SGRs and the radio pulsar PSR J1734−3333. We show that: (i) persistent optical/infrared emission of AXP/SGRs can be fit by the emission from the disk surface, (ii) X-ray enhancement light curves of AXP/SGRs can be produced by the relaxation of the disk that has been pushed back by a soft gamma- ray burst, (iii) Luminosity and rotational properties of SGR 0418+5729 can be achieved simultaneously by a neutron star evolving with a fallback disk, and (iv) rotational properties, including the anomalous breaking index and X-ray luminosity of PSR J1734−3333 can be produced simultaneously in the fallback disk model. The model we use is self-consistent in that we use the same basic disk parameters and do not require special assumptions in any of these explanations

Fallback disks, magnetars and other neutron stars

The presence of matter with angular momentum, in the form of a fallback disk around a young isolated neutron star will determine its evolution. This leads to an understanding of many properties of different classes of young neutron stars, in particular a natural explanation for the period clustering of AXPs, SGRs and XDINs. The spindown or spinup properties of a neutron star are determined by the dipole component of the magnetic field. The natural possibility that magnetars and other neutron stars may have different strengths of the dipole and higher multipole components of the magnetic field is now actually required by observations on the spindown rates of some magnetars. This talk gives a broad overview and some applications of the fallback disk model to particular neutron stars. Salient points are: (i) A fallback disk has already been observed around the AXP 4U 0142+61 some years ago. (ii) The low observed spindown rate of the SGR 0418+5729 provides direct evidence that the dipole component of the field is in the 1012G range. All properties of the SGR 0418+5729 at its present age can be explained by spindown under torques from a fallback disk. (iii) The anomalous braking index of PSR J1734-3333 can also be explained by the fallback disk model which gives the luminosity, period, period derivative and the period second derivative at the present age. (iv) These and all applications to a variety of other sources employ the same disk physics and evolution, differing only in the initial conditions of the disk

Optical and Infrared Emission from the AXPs and SGRs

We show that the irradiated accretion disk model can account for all the optical and infrared observations of the anomalous X-ray pulsars in the persistent state. Model fits do not constrain the outer disk radii, while placing an upper limit to the inner disk radii, and thus to the strength of the dipole component of the stellar magnetic field. While magnetar fields (B_* > 10^{14} G) in higher multipoles are compatible with the irradiated disk model, magnetic dipole components of magnetar strength are not consistent with optical data.Comment: 12 pages, accepted for publication in ApJ Letter

A natural limit on the observable periods of anomalous x-ray pulsars and soft gamma-ray repeaters

We investigate the dependence of the evolution of neutron stars with fallback disks on the strength of the magnetic dipole field of the star. Using the same model as employed by Ertan et al. (2009), we obtain model curves for different dipole fields showing that the neutron stars with magnetic dipole fields greater than ∼ 1013 G on the surface of the star are not likely to become anomalous X‐ray pulsars (AXPs) and soft gamma‐ray repeaters (SGRs). Other sources with conventional dipole fields evolve into the AXP phase if their disk can penetrate the light cylinder. The upper limits to the observed periods of AXP and SGRs could be understood if the disk becomes inactive below a low temperature around 100 K. We summarize our present and earlier results indicated by the evolutionary model curves of these sources with an emphasis on the importance of the minimum disk temperature and the X‐ray irradiation in the long‐term evolution of AXPs and SGRs with fallback disks

On fallback disks and magnetars

The discovery of a disk around the anomalous X-ray pulsar 4U 0142+61, has rekindled the interest in fallback disks around magnetars. We briefly review the assumptions of fallback disk models and magnetar models. Earlier data in optical and near IR bands combined with new Spitzer data in the mid-IR range are compatible with a gas disk. Higher multipole fields with magnetar strengths together with a dipole field of 1012-1013 G on the neutron star surface are compatible with the presence of a disk around the neutron star. The possible presence and properties of a fallback disk after the supernova explosion is a likely initial condition to complement the initial rotation period and initial dipole field in determining the evolutionary paths and different types of isolated neutron stars

Long-term evolution of dim isolated neutron stars

The X-ray dim isolated neutron stars (XDINs) have periods in the same range as the anomalous X-ray pulsars (AXPs) and the soft gamma-ray repeaters (SGRs). We apply the fallback disc model, which explains the period clustering and other properties of AXP/SGRs, to the six XDINs with measured periods and period derivatives. Present properties of XDINs are obtained in evolutionary scenarios with surface dipole magnetic fields B-0 similar to 10(12) G. The XDINs have gone through an accretion epoch with rapid spin-down earlier, and have emerged in their current state, with the X-ray luminosity provided by neutron star cooling and no longer by accretion. Our results indicate that the known XDINs are not likely to be active radio pulsars, as the low B-0, together with their long periods place these sources clearly below the 'death valley'

The effects of rivaroxaban, an oral anticoagulant, on human IVD primary cultures

Introduction: The present study aimed to investigate the potential effects of rivaroxaban, an oral anticoagulant that inhibits the effects of factor Xa, on intact intervertebral disc tissue cells and the extracellular matrix (ECM). Material and methods: Rivaroxaban was applied to primary human cell cultures prepared from tissues of the intervertebral disc. Comparative molecular analyses were performed on non-drug-treated control group samples. Descriptive statistics were presented as the mean +/- standard deviation. An analysis of variance test was performed to determine whether there were significant differences in the mean across the groups. When differences across groups were observed, Tukey's honestly significant difference post-hoc test was used for multiple pairwise comparisons. The significance of the obtained data was determined statistically. The alpha significance value was < 0.05. Results: The cells in the control group and in the rivaroxaban-treated group were viable, healthy, and proliferated (p < 0.05). However, the expression levels of the chondroadherin gene (CHAD), cartilage oligo matrix protein (COMP), matrix metalloproteinase (MMP)-13, and MMP-19 genes were changed (p < 0.05). Conclusions: Although rivaroxaban does not suppress cell proliferation due to morphological, biological, and biochemical changes in the intervertebral disc tissue, it may change the expression of genes that are related to ECM maintenance

Does preparation for childbirth training reduce the cesarean rate?

Purpose: This study was conducted as experimental and prospective to determine the effect of birth preparation training on the birth route preparations of pregnant individuals. Methods: The study was conducted in three state hospitals which operate under Kocaeli State Hospitals Community. The study group included 110 pregnant individuals who attended the hospitals’ birth preparation training classes between 1 January – 30 June 2015 and the control group included 90 pregnant individuals from Kocaeli Maternity Hospital. The chi-squared test was used to measure the differences between groups in classified variables, and the t-test was used for parametric variables. P <0.05 was considered to be significant A survey form was used to identify individual demographic information, obstetric stories, and preferred birth route in order to collect relevant data. Findings: The survey reveals that 67% of the pregnant individuals prefer vaginal birth while 33% prefer cesarean birth. In choosing the birth route, 60% of the pregnant individuals make their own decisions, while 28.2% make the decision together with their partner, and 11.8% report the decision being made by their doctor. It is observed that—after attending the birth training—all of the individuals preferred vaginal birth. For the pregnant individuals, their birth route choices before and after the birth preparation training had been observed as highly statistically significant ( p<0, 005). However, when the choices of the pregnant individuals who participated in birth preparation training is compared to the control group’s choices, no statistical significance was found. Rates of cesarean were alike for both groups. Conclusions and Suggestions: In this study, for the individuals who participate in birth preparation training, the choice of the birth route is found to be affected by age, literacy, and former birth route experienced. However, no significant evidence was found regarding reducing the choice of cesarean. A pregnant individual’s birth route choice will be more healthy as she becomes qualified for, and receives sufficient treatment between the preconception stage to after birth, alternative birth routes, and consultancy for overcoming birth pain and relaxation methods

Effects of etanercept, a tumor necrosis factor receptor fusion protein, on primary cell cultures prepared from intact human intervertebral disc tissue

The aim of the present study was to investigate the effects of etanercept (ETA), a tumor necrosis factor (TNF) inhibitor, on human cell cultures prepared from intact intervertebral disc tissue. ETA is used as a treatment for cases of rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis and ankylosing spondylitis accompanied by moderate or severe joint pain. ETA was applied to primary cell cultures [annulus fibrosus and nucleus pulposus (NP) from intact intervertebral disc tissue]. Cell cultures without ETA treatment served as the control group. Morphological and quantitative molecular analyses of the two groups were performed. The number of viable cells and cell proliferation decreased in the ETA-treated cultures as compared with those in the control group. Furthermore, in the treatment group, the chondroadherin gene, an NP-specific marker, was not expressed after 24 h. By contrast, the cartilage oligo matrix protein was expressed 24, 48 and 72 h post-ETA treatment, while its expression was significantly lower than that in the control group. In addition, the expression of interleukin-1 beta, as well as matrix metallopeptidase-7 and -19, was markedly decreased. Overall, the cell proliferation and gene expression in the ETA-treated cells were significantly different from those in the control group (P<0.05). These results suggest that the treatment duration and dosage of TNF inhibitors, which are used to suppress active inflammation, should be considered in the clinical setting. These biological agents may delay the healing of intervertebral disc tissue damage by slowing cell proliferation and altering gene expression via anabolic and catabolic pathways