White Dwarfs In Ngc6397 And M4: Constraints On The Physics Of Crystallization

We explore the physics of crystallization in the dense Coulomb plasma of the deep interiors of white dwarf stars using the color-magnitude diagram and luminosity function constructed from Hubble Space Telescope photometry of the globular cluster M 4 and compare it with our results for proper motion cleaned Hubble Space Telescope photometry of the globular cluster NGC 6397. We demonstrate that the data are consistent with a binary mixture of carbon and oxygen crystallizing at a value of Gamma higher than the theoretical value for a One Component Plasma (OCP). We show that this result is in line with the latest Molecular Dynamics simulations for binary mixtures of C/O. We discuss implications for future work.Astronom

One-year outcomes of a bilateral randomised prospective clinical trial comparing PRK with mitomycin C and LASIK

Aim: To compare 1-year follow-up results of photorefractive keratectomy (PRK) with mitomycin C (MMC) and laser in situ keratomileusis (LASIK) for custom correction of myopia.Methods: Eighty-eight eyes of 44 patients with moderate myopia were randomised to PRK with 0.002% MMC for 1 min in one eye and LASIK in the fellow eye. the 1-year follow-up was evaluated.Results: There were no differences between LASIK and MMC-PRK eyes preoperatively. Forty-two patients completed the 1-year follow-up. MMC-PRK eyes achieved better uncorrected visual acuity (p=0.03) and better best-spectacle-corrected visual acuity (p<0.001) 1 year after surgery. SE did not differ in the two groups during follow-up (p=0.12). Clinically significant haze was not found in surface ablation eyes. LASIK eyes showed a greater higher-order aberration (p=0.01) and lower contrast sensitivity (p<0.05) than MMC-PRK eyes postoperatively. Excellent vision was reported in 64% of LASIK and 74% of MMC-PRK eyes 1 year after surgery. the corneal resistance factor and corneal hysteresis (ORA, Reichert) were higher in LASIK than in MMC-PRK eyes (p<0.01) at the last follow-up.Conclusions: Wavefront-guided PRK with 0.002% MMC was more effective than wavefront-guided LASIK for correction of moderate myopia. Further research is necessary to determine the optimal concentration, exposure time and long-term corneal side effect of MMC.Universidade Federal de São Paulo, Vis Inst, Dept Ophthalmol, São Paulo, BrazilUniversidade Federal de São Paulo, Vis Inst, Dept Ophthalmol, São Paulo, BrazilWeb of Scienc

Using automated reasoning in the design of an audio-visual communication system

Formal reasoning about how users and systems interact poses a difficult challenge. Interactive systems design provides a context in which the subjective area of human understanding meets the objectivity of computer systems logic. We present results of a case study in the use of automated reasoning to aid the formal analysis of interactive systems. We show how we can use human-factors issues to generate properties of interest, and how we can use model checking and theorem proving to analyse our specifications against those properties. This is part of ongoing work in the development of a tool to allow the automatic translation of interactor based specifications into SMV, and in the analysis of the role which different verification techniques might have during the development of interactive systems.Fundação para a Ciência e Tecnologia - PRAXIS XXI/BD/9562/96

From HCI to software engineering and back

Methods to assess and ensure system usability are becoming increasingly important as market edge becomes less dependent on function and more dependent on ease of use, and as recognition increases that a user's failure to understand how an automated system works may jeapordise its safety. While ultimately only deployment of a system will prove its usability, a number of approaches to early analysis have been proposed that provide some ability to predict the usability and human-error proneness of the fielded system. The majority of these approaches are designed to be used by human factors specialists, require specific expertise that does not fall within the domain of software engineering and fall outside standard software development life cycles. However, amongst this number, some rigorous mathematical methods have been proposed as solutions to the more general problem of ensuring quality of system designs but with limited success. This paper discusses their limitations both in terms of the broader software engineering agenda and in terms of their effectiveness for usability analysis, the opportunities that they offer and discusses what might be done to make them more acceptable and effective. The paper positions those methods that have been effective against less formal usability analysis methods

Tratamento e reciclagem de águas residuárias em sistema intensivo de produção de leite.

bitstream/item/65245/1/CT-75-Tratamento-e-reciclagem-de-aguas.pd