Correcting for the solar wind in pulsar timing observations: the role of simultaneous a nd l ow-frequency observations

The primary goal of the pulsar timing array projects is to detect ultra-low-frequency gravitational waves. The pulsar data sets are affected by numerous noise processes including varying dispersive delays in the interstellar medium and from the solar wind. The solar wind can lead to rapidly changing variations that, with existing telescopes, can be hard to measure and then remove. In this paper we study the possibility of using a low frequency telescope to aid in such correction for the Parkes Pulsar Timing Array (PPTA) and also discuss whether the ultra-wide-bandwidth receiver for the FAST telescope is sufficient to model the solar wind variations. Our key result is that a single wide-bandwidth receiver can be used to model and remove the effect of the solar wind. However, for pulsars that pass close to the Sun such as PSR J1022+1022, the solar wind is so variable that observations at two telescopes separated by a day are insufficient to correct the solar wind effect.Comment: accepted by RA

Expression of syndecan-1 in the retina of diabetes

AIM:To observe the expression of syndecan-1 on epiretinal membranes obtained from patients with proliferative diabetic retinopathy and retina of diabetic rats. METHODS:SD rats were given intraperitoneal injection of streptozotocin to induce diabetes. Ink perfusion and stretched retina were used to observe the retinal blood vessels. Immunohistochemistry staining was used to detect syndecan-1 protein in the rat retina and epiretinal membranes of proliferative diabetic retinopathy. RESULTS:In the diabetic rats of 9-week, peripheral retinal blood vessels shaped tortuously, capillary network was significantly reduced, and parts of the capillary perfusion was bad. In the control group, strong positive staining of syndecan-1 was detected in the nerve fiber layer and ganglion cells, moderate positive staining was observed in the inner plexiform layer and outer segments of photoreceptor, and weak positive staining was detected in the outer plexiform layer. In the retina of diabetic rats, syndecan-1 decreased. Moderate positive staining of syndecan-1 was observed in the nerve fiber layer, ganglion cells and outer segments of photoreceptor, weak positive staining was detected in the inner plexiform layer and outer plexiform layer. Among 13 specimens of epiretinal membranes, weak positive staining of syndecan-1 was detected in 8 cases(61.5%)and negative staining was observed in 5 cases(38.5%). CONCLUSION:Syndecan-1 is down-regulated in the retina of diabetic rats and epiretinal membranes of proliferative diabetic retinopathy