9,545 research outputs found
The soft-focus lens and Anglo-American pictorialism
No full textElectronic version excludes illustrations for which permission has not been granted by the rights holderThe history, practice and aesthetic of the soft focus lens in photography is elucidated and developed from its earliest statements of need to the current time with a particular emphasis on its role in the development of the Pictorialist movement. Using William Crawford's concept of photographic 'syntax', the use of the soft focus lens is explored as an example of how technology shapes style.
A detailed study of the soft focus lenses from the earliest forms to the present is presented, enumerating the core properties of pinhole, early experimental and commercial soft focus lenses. This was researched via published texts in period journals, advertising, private correspondence, interviews, and the lenses themselves. The author conducted a wide range of in-studio experiments with both period and contemporary soft focus lenses to evaluate their character and distinct features, as well as to validate source material.
Nodal points of this history and development are explored in the critical debate between the diffuse and sharp photographic image, beginning with the competition between the calotype and daguerreotype. The role of George Davison's The Old Farmstead is presented as well as the invention of the first modern soft focus lens, the Dallmeyer-Bergheim, and its function in the development of the popular Pictorialist lens, the Pinkham & Smith Semi-Achromatic. The trajectory of the soft focus lens is plotted against the Pictorialist movement, noting the correlation betwixt them, and the modern renaissance of soft focus lenses and the diffuse aesthetic.
This thesis presents a unique history of photography modeled around the determining character of technology and the interdependency of syntax, style and art
Non-Uniform Metasurface Luneburg Lens Antenna Design
No full textA metasurfing concept is demonstrated and applied in the design of Luneburg lens antennas. Using an array of size-varying circular patches on a dielectric substrate inside a parallel-plate waveguide (PPW) structure variable surface impedance is obtained, which realizes an equivalent refraction index as that of a Luneburg lens. The obtained lens has good bandwidth characteristics and significant fabrication advantages with respect to conventional dielectric lenses. Based on this PPW lens, an H-plane antenna has been designed and simulated
An epidemiological assessment of lens opacifications that impaired vision in patients injected with radium-224
No full textThe incidence of lens opacifications that impaired vision (cataract) was analyzed among 831 patients who were injected with known dosages of 224Ra in Germany shortly after World War II. The dependence of the incidence on dosage, i.e., injected activity per unit body weight, and on time after treatment was determined. The observations are equally consistent with proportionality of the incidence of cataract to the square of dosage or with a linear dependence beyond a threshold of 0.5 MBq/kg. The possibility of a linear dependence without threshold was strongly rejected (P less than 0.001). The analysis of temporal dependences yielded a component that was correlated with the injected amount of 224Ra and a component that was uncorrelated. The former was inferred by a maximum likelihood analysis to increase approximately as the square of the time after treatment. The component unrelated to the treatment was found to increase steeply with age and to become dominant within the collective of patients between age 50 and 60. The relative magnitudes of the two components were such that a fraction of 55 to 60% of the total of 58 cataracts had to be ascribed to the dose-related incidence. Impaired vision due to cataract was diagnosed before age 54 in 25 cases. In terms of injected activity per unit body weight no dependence of the sensitivity on age was found; specifically there was no indication of a faster occurrence of the treatment-related cataracts in patients treated at older ages
Protecting Animals 36: Author Witi Ihimaera
No full textIn this very special episode of Knowing Animals I am joined by beloved New Zealand author Witi Ihimaera. Witi has written many books featuring nonhuman animals. He offers us a non-colonial lens through which to think about the human/nonhuman relationship
Interplay between network configurations and network governance mechanisms in supply networks a systematic literature review
No full textPurpose: This work systematically reviews the extant academic management literature on supply networks. It specifically examines how network configurations and network governance mechanisms influence each other in supply networks.
Design: 125 analytical and empirical studies were identified using an evidence-based approach to review the literature mainly published between 1985 and 2012.
Synthesis: Drawing on a multi-disciplinary theoretical foundation, this work develops an integrative framework to identify three distinct yet interdependent themes that characterize the study of supply networks: a) Network Configurations (structures and relationships); b) Network Governance Mechanisms (formal and informal); and c) The Interplay between Network Configurations and Network Governance Mechanisms.
Findings: Network configurations and network governance mechanisms mutually influence each other and cannot be considered in isolation. Formal and informal governance mechanisms provide better control when used as complements rather than as substitutes. The choice of governance mechanism depends on the nature of exchange; role of management; desired level of control; level of flexibility in formal contracts; and complementary role of formal and informal governance mechanism.
Research implications: This nascent field has thematic and methodological research opportunities for academics. Comparative network analysis using longitudinal case studies offers a rich area for further study.
Practical Implications: The complexity surrounding the conflicting roles of managers at the organisation and network levels poses a significant challenge during the development and implementation stage of strategic network policies.
Originality/value: This review reveals that formal and informal governance mechanisms provide better control when used as complements rather than as substitutes
High Aperture Efficiency Plastic Lens Antenna for Scanning Lens Phased Array at 180 GHz
No full textIn this contribution, we present a plastic resonant leaky-wave lens antenna with high aperture efficiency (>80%) over a 1:2 bandwidth centered at 180 GHz. This antenna can be integrated in a scanning lens phased array architecture for next-generation wireless and sensing applications that require high-directivity steerable beams. The high aperture efficiency is achieved thanks to the combination of annular corrugations in the ground plane with a leaky-wave resonant cavity. A WR-5 (140-220 GHz) prototype is manufactured and measured in terms of reflection coefficient, radiation patterns, directivity, losses, cross-polarization and scan performance, showing excellent agreement with simulations.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Tera-Hertz Sensin
Citizenship in Media Discourse in Bosnia and Herzegovina, Croatia, Montenegro, and Serbia
No full textThe aim of this paper is to systematize existing research on media reporting related to various aspects of citizenship, and to contribute with a primary analysis of media content, in order to define how the leading print media in four states (Bosnia and Herzegovina, Croatia, Montenegro, and Serbia) reported on these issues. After establishing the profile of each state, this paper provides a profile of the analysed media, followed by a short summary of how these media reported on selected citizenship-related issues and topics. The main trends in media reporting were analysed within an interdisciplinary theoretical framework that includes the selected approaches / theories in media and communication studies, but also the studies on citizenship. The main assumption is that the mass media in the states under scrutiny, while reporting on citizenship-related issues,, have mostly legitimized governments in determining their citizenship policies. Only in Montenegro and, to some extent, in Croatia, when it comes to external voting, have oppositional media outlets continuously criticized the “official” citizenship policies, while in other states the leading media discourses lack a polemical and critical stance towards citizenship-related issues
Efron Grading Scales for Contact Lens Complications, Butterworth-Heinemann
No full textThe Efron Grading Scales provide a standard clinical reference for describing the severity of contact lens complications. Professor Nathan Efron, international lecturer in the field of the ocular response to contact lens wear and author of over 500 scientific works, developed the unique scales. They provide practitioners with a simple method of ocular condition grading, against which any future tissue change may be assessed and therefore enabling choices as to the best course of action. \ud
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The 16 sets of grading images cover the key anterior ocular complications of contact lens wear. The conditions are illustrated in five stages of increasing severity from 0 to 4, with 'traffic light' colour banding from green (normal) to red (severe) - providing a simple and convenient aid for the optical professional
Core-Shell Leaky-Wave Lens Antenna for 150GHz Fly’s Eye Communication Systems
No full textThis work presents a novel lens antenna architecture based on a core-shell lens design with a leaky-wave in-packaged antenna at 150GHz. An electrically small core lens made of dense dielectric material is used to enhance the radiation of the in-packaged antenna. A low-loss dielectric shell lens with electrically large dimensions is then added to provide high directivity. A microstrip feeding network for connection to a 150GHz chipset is then also discussed. The proposed lens antenna provides good quality patterns with aperture efficiencies above 80% over a bandwidth of 20%.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Tera-Hertz SensingElectronic
Does HIV accelerate the aging process? An assessment of clinical, ophthalmic and serum parameters in HIV-infected individuals in South Africa
No full textHIV-infected individuals are at increased risk of age-related non-AIDS morbidity and mortality compared with HIV-uninfected persons. It is speculated that HIV-infected individuals may not only be aging chronologically, but also undergoing accelerated biological aging. This is supported by clinical reports of conditions classically associated with the normal aging process appearing at an earlier age in HIV-infected persons compared to age-matched controls.
Chronological age is an imprecise measure of biological aging due to inter-individual differences in rates of aging and therefore ‘biomarkers of aging’ may be used to assess biological age. The eye may be a uniquely useful site as a model of aging. It is easily accessible for examination and several components can be measured and assessed objectively e.g. lens density, retinal vascular calibre, corneal endothelial cell counts and the retinal nerve fibre layer thickness.
This case-control study of 504 adults recruited from one district in Cape Town, South Africa assessed whether HIV-infected individuals have more advanced ocular aging, systemic frailty and cellular senescence than an HIV-uninfected group of similar age. Accelerated biological aging was demonstrated in HIV-infected individuals compared to their uninfected counterparts. HIV infection was also associated with frailty. Ocular parameters provided evidence of greater aging within the HIV-infected group, particularly objective measurement of retinal vascular calibre and lens density. These data suggest that as well as increased biological aging at a cellular and systemic level, ocular aging occurs as part of the accelerated aging phenotype in HIV infection.
This study provides novel data about accelerated biological aging in sub-Saharan Africa and a platform for addressing future research questions relating to accelerated aging trajectories in HIV infection, the relative contributions of the infection and antiretroviral therapy, and whether biological age is dependent upon the duration of untreated disease or nadir CD4 count. As the HIV-infected population continues to age and expand, accelerated biological aging may have wideranging implications for the burden and management of HIV-related morbidity
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