Browsing by Subject "Blindness"
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Item Open Access Blindness and visual impairment in opera(SAGE Publications, 2018) Aydin, P.; Ritch, R.; O’Dwyer, J.Purpose: The performing arts mirror the human condition. This study sought to analyze the reasons for inclusion of visually impaired characters in opera, the cause of the blindness or near blindness, and the dramatic purpose of the blindness in the storyline. Methods: We reviewed operas from the 18th century to 2010 and included all characters with ocular problems. We classified the cause of each character’s ocular problem (organic, nonorganic, and other) in relation to the thematic setting of the opera: biblical and mythical, blind beggars or blind musicians, historical (real or fictional characters), and contemporary or futuristic. Results: Cases of blindness in 55 characters (2 as a choir) from 38 operas were detected over 3 centuries of repertoire: 11 had trauma-related visual impairment, 5 had congenital blindness, 18 had visual impairment of unknown cause, 9 had psychogenic or malingering blindness, and 12 were symbolic or miracle-related. One opera featured an ophthalmologist curing a patient. Conclusions: The research illustrates that visual impairment was frequently used as an artistic device to enhance the intent and situate an opera in its time.Item Open Access Generalized ID-based elgamal signatures and extensions(Bilkent University, 2008) Kalkan, SaidID-based cryptography helps us to simplify key management process in traditional public key infrastructures. Any public information such as the e-mail address, name, etc., can be used as a public key and this solves the problem of obtaining the public key of a party and checking that its certificate is valid. ID-based cryptography has been a very active area of research in cryptography since bilinear pairings were introduced as a cryptographic tool. There have been many proposals for ID-based signatures recently. In this thesis, we introduce the concept of generalized ID-based ElGamal signatures and show that most of the proposed ID-based signature schemes in the literature are special instances of this generalized scheme. We also investigate ID-based signatures providing additional properties. Signature schemes with message recovery provide the feature that the message is recoverable from the signature and hence does not need to be transmitted separately. Blind signatures provide the feature that a user is able to get a signature without giving the actual message to the signer. Finally, signcryption schemes fulfill the job of a digital signature and encryption in a single step with a lower computational cost. We generalize the ID-based signatures providing these properties and obtain numerous new signatures which have not been explored before. The generalized ID-based signatures we described provide a unified framework for ID-based ElGamal signatures and extensions. Additionally, some of our blind signatures turn out to be more efficient than the previously proposed schemes.Item Open Access The visual cortices of congenitally and non-congenitally blind individuals become a part of cognitive control network(Bilkent University, 2023-12) Duymuş, HasanNeural plasticity is crucial for understanding the extent to which a biological structure determines its function. As such, the fate of visual and auditory cortices when deprived of their standard inputs has immense significance in neuroscientific research. Empirical findings suggest that the visual cortex of the congenital and early blind activates across a very wide range of tasks in auditory, tactile and olfactory modalities. We hypothesized that these regions may transform into task positive multiple demand (MD) regions. A key feature of these regions is that they activate to all kinds of tasks in all kinds of modalities. In this study, we investigate whether deprived cortices in blind exhibit key characteristic inherent to fronto-parietal MD regions. We had congenitally and non-congenitally blind participants done four fMRI cognitive control tasks in tactile and auditory modalities. The visual cortices of the blind group showed (1) intense activity during more demanding conditions of the four diverse tasks along with the fronto-parietal control regions, (2) the same set of occipital voxels in blind participants activated across diverse modalities under increased cognitive demands of the four diverse tasks. Our findings suggest that deprived visual cortices of the blind, in fact, become a part of cognitive control network.