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The wireless spectrum is a natural resource upon which we all depend in more ways than we realize. While our personal and professional lives thrive on mobile broadband, a plethora of other applications, such as weather forecasting, climate science, astronomy, space exploration, and civil/military navigation also critically depend on the radio spectrum. Although these technologies are vastly different, they all share a common need for more spectrum and increasingly converge to the same bands. Currently, technological and policy frameworks are insufficient to facilitate the required mutual trust across distinct applications, and ensure their protection and harmonious coexistence. This article discusses Radio Dynamic Zones (RDZ) as experimental platforms for large-scale research on spectrum coexistence of disparate stakeholders. We consider three representative stakeholder technologies that have experienced exponential growth in spectrum needs and capabilities: consumer broadband, microwave remote sensing, and radio astronomy. We detail emerging coexistence issues across these stakeholders that can inform the design of RDZs. We then conceptualize an RDZ architecture and desired features and discuss grand research challenges towards their realization.

Purpose: To investigate retinal perfusion by optical coherence tomography (OCT)-angiography and choroidal vascular features using an OCT-based image binarization method in patients with Behçet’s disease (BD) without clinical ocular involvement. Methods: This study included 38 patients with non-ocular BD and 35 healthy participants. Macular region was evaluated with OCT-angiography (Optovue, Inc., Fremont, CA). A 6.0 × 6.0 mm rectanglescan centred on the fovea was used to record the scans. The enhanced depth imaging OCT scans (Heidelberg Eye Explorer version 1.8.6.0; Heidelberg Engineering) of the macula and peripapillary scans of the optic nerve head were binarized using ImageJ software (National Institutes of Health, Bethesda, MD, USA). The luminal area (LA), stromal area (SA), total choroidal area (TCA), and choroidal thickness (CT) were analysed. The choroidal vascularity index (CVI) was calculated as the ratio of the LA to the TCA. Results: Vessel density values of the superficial and deep macular capillary plexus were similar between the two groups (all p> 0.05). There was no significant difference between the groups in terms of the CT and TCA values in the macula and in all peripapillary sectors (all p> 0.05). However, the macula and temporal, nasal, and inferior sectors of the peripapillary area had significantly lower CVI values in the BD group compared with controls (p= 0.009, p= 0.002, p= 0.010, and p= 0.008, respectively). Conclusions: Retinal microperfusion deficit was not observed in non-ocular Behçet patients. CVI may be a more robust marker than CT to indicate choroidal perfusion. A reduced CVI may suggest subclinical ocular involvement and choroidal ischemia in these patients.

Purpose: This study aimed to evaluate choroidal thickness (CT) and choroidal vascularity index (CVI) in patients with Graves’ disease (GD) without ocular involvement.Methods: Fifty patients diagnosed with GD and 50 age and gender matched healthy control subjects were retrospectively evaluated. Measurements were taken from five different points on CT images. Choroid images were classified as lumen regions (LA) and stromal regions (SA) using the image binarization method. CVI was calculated by dividing LA by the total choroidal area (TCA). The effects of Thyrotropin Receptor Antibody (TRAb), age, GD duration, blood pressure, axial length measurements, and intraocular pressure were analyzed on CT and CVI measurements.Results: Mean age was 40.1 ± 13.5 years in the patient group and 39.3 ± 13.6 years in the control group (p= 0.89). There was no significant difference between the GD group and control group in terms of CT measurements. There was a significant difference between the mean CVI measurements of the GD group and control group (68.03 ± 3.41 and 66.62 ± 3.11, respectively) (p< 0.001). Univariate linear regression analysis revealed a positive correlation between TRAb and CVI (p= 0.013).Conclusion: While there was no significant difference between the CT measurements of the GD group and the control group, the GD group had significantly higher CVI measurements.

Purpose This study aims to compare the cytotoxic, apoptotic, and oxidative effects of a new cationic disinfectant, Akacid Plus, with chlorhexidine, on the human corneal epithelial cell line.Methods Time-dependent cytotoxicity studies were performed with the Alamar Blue method. Apoptotic activity was investigated by flow cytometric methods. Reactive oxygen species levels were measured with the ROS cellular test kit. BAX, BCL2 and caspase 3, 9, 12 mRNA expressions were evaluated by PCR, as well as BAX and BCL2 protein expressions by Western-Blot.Results At the fifth minute of the treatment, the viability was 68.15% with Akacid Plus and 43.95% with chlorhexidine. At the 15th minute, no significant difference was observed with both solutions. In the apoptotic evaluation, Akacid Plus significantly increased the early and late apoptotic activity in the cell line (p< 0.0001), while a significant increase was observed in late apoptosis and necrosis levels with chlorhexidine (p< 0.001). Chlorhexidine also induced gene expression of BAX, BCL2, caspase 3, 9 and BAX proteins (p< 0.05), while reducing protein expression of BCL2 (p< 0.001). Akacid Plus induced the gene expressions of BCL2, CASP3 and caspase 9, reduced gene expressions of BAX and caspase 12 and protein expression of BCL2 (p< 0.05). No significant difference was observed in the ROS level with both solutions (p> 0.05).Conclusion Due to the widespread use of cationic polymers in ophthalmology, this new molecule with high antimicrobial activity and relatively low cytotoxicity may be of interest for clinical use. Further investigations are necessary to fully understand the ophthalmologic potential of this solution.

In this study, the corrosion behavior of ferritic stainless steel with 1 wt. % V was determined by AC impedance technique and mass-loss method. The samples were cast, then shaped by forging. 0.1 M H2SO4and 0.3 M HCl acid solutions were used as corrosive environments. The samples were classified into three groups. In the first group, samples were unhomogenized, remaining in production condition. The second and third group samples were exposed to homogenization at 1100°C for 30 min or 180 min, respectively, and then quenched. SEM investigations were performed for samples exposed to corrosion for 30 min and 360 min. Subsequently, it was determined that adding vanadium increased corrosion resistance in chloric acid solution but has no helpful effect in sulphuric acid solution, according to AC impedance test results. The mass-loss results showed that vanadium increased corrosion resistance of ferritic stainless steel in both solutions.