Graphene revealed a number of unique properties beneficial for electronics. However, graphene does not have an energy band-gap, which presents a serious hurdle for its applications in digital logic gates. The efforts to induce a band-gap in graphene via quantum confinement or surface functionalization have not resulted in a breakthrough.Here we show that the negative differential resistance experimentally observed in graphene field-effect transistors of "conventional" design allows for construction of viable non-Boolean computational architectures with the gap-less graphene. The negative differential resistance -observed under certain biasing schemes -is an intrinsic property of graphene resulting from its symmetric band structure. Our atomistic modeling shows that the negative differential resistance appears not only in the drift-diffusion regime but also in the ballistic regime at the nanometer-scalealthough the physics changes. The obtained results present a conceptual change in graphene research and indicate an alternative route for graphene's applications in information processing.
The coherent, interlayer conductance of misoriented bilayer graphene ribbons is a strong function of the Fermi energy and magnetic field. Edge states can result in a large peak in the interlayer transmission at the charge neutrality point that is several orders of magnitude larger than the surrounding low-energy transmission. The coherent interlayer conductance is consistently asymmetric around the charge neutrality point for all structures with the value differing by up to 3 orders of magnitude at Ef = ±0.05 eV. The low-energy states exhibit a high magnetoconductance ratio, and the magnetoconductance ratio tends to increase as the width of the ribbons decrease. The maximum value for the 35 nm wide bilayer ribbons at 10 T is 15 000%. Non-equilibrium Green's function calculations of the interlayer transport properties are also supported by semi-analytical calculations based on Fermi's Golden Rule.
Original Research Article Introduction: Myopia is an important cause of visual disability throughout the world, and in its higher forms, it is also an important cause of blindness. Myopia is one of the most common causes of visual disability of the eye and important cause of defective vision affecting the younger age groups. Objective: In our study, efforts are made to find out incidence, prevalence, various symptoms and signs of high and pathological myopia in different age groups and their visual acuity. Methods: This is a prospective study of the Demographic pattern, Posterior segment changes and its effect on visual acuity in patients with High and Pathological Myopia in 100 cases attending in Ophthalmology Department, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh for a period from June 2015 to May 2017. The patients with refractive error of ≥-6D and with normal corneal curvature are included in the study. Patients with refractive error of <-6D, with index myopia, with abnormal corneal curvature (Curvature Myopia) are excluded from the study. Results: Out of these 100 cases, 196 eyes were diagnosed to have high myopia (>-6.00 Dsph) and pathological Myopia (>-15 D sph) after thorough clinical examination & investigations. Conclusion: High myopic and pathological myopic patients tend to suffer from compromised quality of life owing to various influences from functional, psychological, cosmetic, and financialfactors. So these patients should be given special care, and all modalities of treatment were instituted to improve the quality of life and vision.
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