Dyonic Reissner-Nordstrom Black Holes and Superradiant Stability

Black holes immersed in magnetic fields are believed to be important systems in astrophysics. One interesting topic on these systems is their superradiant stability property. In the present paper, we analytically obtain the superradiantly stable regime for the asymptotically flat dyonic Reissner-Nordstrom black holes with charged massive scalar perturbation. The effective potential experienced by the scalar perturbation in the dyonic black hole background is obtained and analyzed. It is found that the dyonic black hole is superradiantly stable in the regime $0<r_{-}/r_{+}<2/3$, where $r_\pm$ are the event horizons of the dyonic black hole. Compared with the purely electrically charged Reissner-Nordstrom black hole case, our result indicates that the additional coupling of the charged scalar perturbation with the magnetic field makes the black hole and scalar perturbation system more superradiantly unstable, which provides further evidence on the instability induced by magnetic field in black hole superradiance process

Treatment of proliferative diabetic retinopathy by vitrectomy combined with retinal photocoagulation

AIM: To evaluate clinical effect of vitrectomy combined with retinal photocoagulation for proliferative diabetic retinopathy(PDR).<p>METHODS:A retrospective analysis 72 patients(104 eyes)with PDR who underwent vitrectomy, postoperative fundus fluorescein angiography and retinal photocoagulation within 4wk, from July 2009 to November 2012 in our hospital. All the patients were followed up for more than 12mo, analysising the clinical data of preoperative, postoperative, final corrected vision and the operation complications.<p>RESULTS:The increasing rate of visual acuity after retinal photocoagulation(the last retinal photocoagulation)within 1wk was 88.5%(92/104), 1mo was 92.3%(96/104), 3mo was 90.4%(94/104)and one eye had neovascular glaucoma, 6mo was 88.5%(92/104)and one eye had retinal detachment, 12mo was 80.8%(84/104)and 2 eyes with silicone oil emulsification. Along with the development of diabetic retinopathy, the increasing rate of visual acuity declined, complications of silicone oil eye operation increased, especially in eyes with proliferative diabetic retinopathy in phase five or six.<p>CONCLUSION:Vitrectomy combined with retinal photocoagulation in treatment of PDR is effective and safe. Postoperative fundus fluorescein angiography can have a definite object in view of retinal photocoagulation after vitrectomy, which can reduce excessive photocoagulation and prevent light coagulation deficiencies, while improve the visual acuity effectively and reduce the complications