The stone roof of the tholos of Athena Pronaia in Delphi: structural hypotheses starting from fragments of marble tiles

This contribution is the first step of a multi-disciplinary research project, aimed at studying the roof of the tholos of Athena Pronaia in Delphi, dating back to the first decades of the 4th century BC. The starting point of this research is the fascination exerted by the tectonic quality of the temple, comprising some complex fragments of marble tiles belonging to the roof of the tholos. Despite the number of studies on this sanctuary, the poor state of preservation and lack of original material did not allow archaeologists to perform concluding research on its original configuration, in particular with reference to the reconstruction of the roof. Aware of the complexity of this topic, this contribution aims at exploring two possibilities, namely, on the one hand, that the fragments of tiles constitute elements supported by a wooden structure, and on the other hand, that they are structural elements of a stone system subjected to compressive stresses. Our contribution intends to serve as food for thought on the need for archaeological studies to be accompanied not only by advanced surveys in the field, aimed at the precise definition of the geometry of the finds, but also by architectural and structural investigations which make it possible to verify the feasibility of the hypothetical reconstructions of the architectural elements aware of the construction techniques used in the past

Wet oxidation of GeSi at (700)C

About 500-nm-thick films of Ge0.36Si0.64 and Ge0.28Si0.72 grown epitaxially on (100)Si have been oxidized at 700-degrees-C in wet ambient. A uniform GexSi1-xO2 oxide layer forms with a smooth interface between it and the unoxidized GexSi1-x layer below. The composition and structure of that layer remains unchanged as monitored by backscattering spectrometry or cross-sectional transmission electronic microscopy. The oxide of both samples grows as square root of oxidation duration. The parabolic rate constant increases with the Ge content and is larger than that for wet oxidation of pure Si at the same temperature. The absence of a regime of linear growth at this relatively low temperature indicates a much enhanced linear rate constant

Propagation of focused scalar and vector vortex beams in anisotropic media:A semi-analytical approach

In the field of structured light, the study of optical vortices and their vectorial extension--vectorial vortex beams--has garnered substantial interest due to their unique phase and polarisation properties, which make them appealing for many potential applications. Combining the advantages of vortex beams and anisotropic materials, new possibilities for electromagnetic field tailoring can be achieved in nonlinear optics, quantum and topological photonics. These applications call for a comprehensive modelling framework that accounts for properties of both anisotropic materials and vector vortex beams. In this paper, we describe a semi-analytical model that extends the vectorial diffraction theory to focused vortex beams propagating through a uniaxial slab, considering the cases of scalar and vectorial vortexes in the common framework of a Laguerre-Gaussian modes. The model aims to provide a comprehensive description of the methodology, enabling the implementation of complex beams transmission through, reflection from and propagation in uniaxial anisotropic materials for specific applications. We apply the developed approach to propagation of high-order vortex beams in uniaxial materials with various dispersion characteristics> elliptic, hyperbolic and epsilon-near-zero regimes. We show how variations of the medium anisotropy modify the beam structure due to the vectorial nature of their interaction, which results from the different permittivities of the medium for transverse and longitudinal field components. The applicability of the approach can be extended to artificially structured media if they can described by effective medium parameters. The developed formalism will be useful for modelling of interaction of complex beams with uniaxial materials, allowing a common framework for a large variety of situations, which can also be extended beyond the electromagnetic waves

Transient effects in the backscattered current of a Luttinger liquid

We study the backscattered current in a Luttinger liquid in the presence of a point like weak impurity switched on at finite time, taking into account finite-temperature effects. We show how the well-known results for a static impurity are distorted. We derive a dimensionless parameter $\tau_{R}$ as function of the electron-electron interaction and the temperature, such that for $\tau_{R} 1$) the switching process is relevant (irrelevant). Our results suggest the possibility of determining the value of the Luttinger parameter $K$ through time measurements in transport experiments at fixed voltage.Comment: 8 pages, 3 figures. To appear in Physical Review

Knowledge, attitudes and self-care practices of patients with glaucoma in uThungulu in KwaZulu-Natal

Background: Glaucoma remains one of the leading causes of blindness in South Africa. Early detection, effective treatment and strict compliance with treatment are instrumental to prevent further damage to the optic nerve and thus preserve vision. Aim: The purpose of this study was to assess the knowledge, attitude and self-care practices of patients with glaucoma in KwaZulu-Natal. Setting: The study was conducted in the ophthalmology outpatient department of a public hospital and a private ophthalmology practice in the uThungulu district. Methods: This was an observational, analytic, cross-sectional study. Structured questionnaires assessing knowledge, attitudes and self-care practices were administered to patients presenting for follow-up glaucoma management. Results: The median age of the 384 patients in this study was 60 (interquartile range [IQR] 48.5–69.5) and 59 years (IQR 49.0–66.5) for males and females, respectively (p > 0.05). Two hundred and thirty-eight (62.0%) patients had good knowledge of glaucoma. Age, gender and duration of glaucoma diagnosis were significantly associated with good knowledge of glaucoma. Three hundred and forty-four (89.6%) patients reported having good self-care practices. Patients over the age of 65 years were significantly less likely to have good self-care practices compared to patients aged 26–45 years (odds ratio [OR]: 0.2, confidence interval [CI]: 0.1–0.6, p = 0.01). Good knowledge of glaucoma was significantly associated with good self-care practices of glaucoma (p < 0.001). Conclusion: Elderly patients do not have sufficient knowledge of glaucoma and have poor self-care glaucoma practices. It is important to involve family members of these patients in the education and counselling of glaucoma to facilitate improved disease management

Exposing the human nude phenotype [4]

Peer reviewedSubmitted Versio