110 research outputs found
Ultra-luminous X-ray sources as super-critical propellers
We study the evolution of newborn neutron stars in high-mass X-ray binaries
interacting with a wind-fed super-Eddington disk. The inner disk is regularized
to a radiation-dominated quasi-spherical configuration for which we calculate
the inner radius of the disk, the total luminosity of the system and the torque
acting on the neutron star accordingly, following the evolution of the system
through the ejector and early propeller stages. We find that the systems with
G pass through a short () ejector stage
appearing as supernova impostors followed by a propeller stage lasting . In the super-critical propeller stage the system is still
bright () due to the spindown power and
therefore appears as an ultra-luminous X-ray source (ULX). The system evolves
into pulsating ULX (PULX) when the neutron star spins down to a period ( s) allowing for accretion onto its surface to commence. Systems with lower
magnetic fields, G, pass through a long ()
super-critical propeller stage with luminosities similar to those of the
ultra-luminous super-soft sources (ULS), . The equilibrium periods of these systems in the accretion stage is
about , which is much smaller than the typical period range of
PULX observed to date. Such systems could have a larger population, but their
pulsations would be elusive due to the smaller size of the magnetosphere. Our
results suggest that the ULS and some nonpulsating ULX are rapidly spinning and
highly magnetized young neutron stars at the super-critical propeller stage.Comment: ApJ in press. 9 pages, 4 figure
The anomalous x-ray pulsar 4U 0142+61: a neutron star with a gaseous fallback disk
The recent detection of the anomalous X-ray pulsar (AXP) 4U 0142+61 in the mid infrared with the Spitzer Observatory (Wang, Chakrabarty & Kaplan 2006) constitutes the first instance for a disk around an AXP. We show, by analyzing earlier optical and near IR data together with the recent data, that the overall broad band data can be reproduced by a single irradiated and viscously heated disk model
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
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
Exchange Rate Pass-Through in Turkey : Has it Changed and to What Extent?
This study analyses the impact of exchange rates on domestic prices in Turkey. We seek to demonstrate the variations (if any) in the exchange rate pass-through across different exchange rate regimes, identify the determinants of this change, and characterize the degree and extent of pass-through across different sub-sectors. Our empirical results reveal that the pass-through of exchange rates to domestic prices has declined in the post-2001 period in comparison with the earlier episodes –thanks to a decline in the “indexation” behavior. These findings suggest that switching to floating exchange rate regime and implementing an ambitious disinflation policy have contributed, to a large extent, to the reduction in the pass-through. Nevertheless, the impact of exchange rate on inflation, especially in the traded good is still notable, pointing out that the effect of nominal exchange rate movement on relative prices have increased in the float period.Exchange rate pass-through, Time-varying parameters, Seemingly unrelated regressions, Disinflation, Floating exchange rate regime
The effects of the seeds of Galeopsis ladanum on fattening performance in quails and occurrence of rhabdomyolysis in rats
This study was conducted to investigate the effect of Galeopsis ladanum seeds on rhabdomyolysis occurrence in rats as an animal model and fattening performance of quails. Control group was fed with basal diet without G. ladanum seeds. Diets of treatment groups contained 2 or 4% of G. ladanum seeds, respectively. All animals, quails and rats were fed individually. At the end of the study, 2 and 4% of G. ladanum seeds in the diets did not have reverse effect on body weight, weight gain and feed intake in quails. Besides, treatment group one had a better feed conversion ratio at the end of the third week (p<0.05) and up to 28 days of age (p<0.05). At the end of the feeding period, quails were slaughtered and their drumsticks were fed to the rats either raw or grilled. After consumption of the meat, their serum and organs were subjected to biochemical and pathologic investigations. Although, no pathological finding was observed in the tissue samples, serum myoglobin and enzyme levels were found to be higher than that in the control group (p<0.01). Although, no pathological finding was observed in the tissue samples prepared from rats and quails for histopathological examination, the increase in serum myoglobin and enzyme levels may be due to subcellular changes in the target tissues of toxic substance.Keywords: Galeopsis ladanum, performance, rhabdomyolysis, quai
Erytrocyte membrane anionic charge in type 2 diabetic patients with retinopathy
BACKGROUND: The Steno hypothesis states that changes in basement membrane anionic charge leads to diabetic microvascular complications. In diabetic nephropathy, loss of basement membrane glycosaminoglycans and the association between glomerular basement membrane heparan sulphate and proteinuria has been documented. A correlation between erythrocyte surface and the glomerular capillary wall charges has also been observed. The aim of this study is to evaluate the relationship between retinopathy and erythrocyte anionic charge and urinary glycosaminoglycan excretion in type 2 diabetic patients. METHODS: 49 subjects (58 ± 7 yrs, M/F 27/22) with type 2 diabetes with proliferative retinopathy (n = 13), nonproliferative retinopathy (n = 13) and without retinopathy (n = 23) were included in the study. 38 healthy subjects were selected as control group (57 ± 5 yrs, M/F 19/19). Erythrocyte anionic charge (EAC) was determined by the binding of the cationic dye, alcian blue. Urinary glycosaminoglycan and microalbumin excretion were measured. RESULTS: EAC was significantly decreased in diabetic patients with retinopathy (255 ± 30 ng alcian blue/10(6 )RBC, 312 ± 30 ng alcian blue/10(6 )RBC for diabetic and control groups respectively, p < 0.001). We did not observe an association between urinary GAG and microalbumin excretion and diabetic retinopathy. EAC is found to be negatively corralated with microalbuminuria in all groups. CONCLUSIONS: We conclude that type 2 diabetic patients with low erythrocyte anionic charge are associated with diabetic retinopathy. Reduction of negative charge of basement membranes may indicate general changes in microvasculature rather than retinopathy. More prospective and large studies needs to clarify the role of glycosaminoglycans on progression of retinopathy in type 2 diabetic patients
The genetic structure of the Turkish population reveals high levels of variation and admixture
The construction of population-based variomes has contributed substantially to our understanding of the genetic basis of human inherited disease. Here, we investigated the genetic structure of Turkey from 3,362 unrelated subjects whose whole exomes (n = 2,589) or whole genomes (n = 773) were sequenced to generate a Turkish (TR) Variome that should serve to facilitate disease gene discovery in Turkey. Consistent with the history of present-day Turkey as a crossroads between Europe and Asia, we found extensive admixture between Balkan, Caucasus, Middle Eastern, and European populations with a closer genetic relationship of the TR population to Europeans than hitherto appreciated. We determined that 50% of TR individuals had high inbreeding coefficients (≥0.0156) with runs of homozygosity longer than 4 Mb being found exclusively in the TR population when compared to 1000 Genomes Project populations. We also found that 28% of exome and 49% of genome variants in the very rare range (allele frequency < 0.005) are unique to the modern TR population. We annotated these variants based on their functional consequences to establish a TR Variome containing alleles of potential medical relevance, a repository of homozygous loss-of-function variants and a TR reference panel for genotype imputation using high-quality haplotypes, to facilitate genome-wide association studies. In addition to providing information on the genetic structure of the modern TR population, these data provide an invaluable resource for future studies to identify variants that are associated with specific phenotypes as well as establishing the phenotypic consequences of mutations in specific genes
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
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