759 resultados para Apertureless aplanatic lens


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Ascochyta blight, caused by Ascochyta lentis , is one of the most globally important diseases of lentil. Breeding for host resistance has been suggested as an efficient means to control this disease. This paper summarizes existing studies of the characteristics and control of Ascochyta blight in lentil, genetics of resistance to Ascochyta blight and genetic variations among pathogen populations (isolates). Breeding methods for control of the disease are discussed. Six pathotypes of A. lentis have been reported. Many resistant cultivars/lines have been identified in both cultivated and wild lentil. Resistance to Ascochyta blight in lentil is mainly under the control of major genes, but minor genes also play a role. Current breeding programmes are based on crossing resistant and high-yielding cultivars and multilocation testing. Gene pyramiding, exploring slow blighting and partial resistance, and using genes present in wild relatives will be the methods used in the future. Identification of more sources of resistance genes, good characterization of the host-pathogen system, and identification of molecular markers tightly linked to resistance genes are suggested as the key areas for future study.

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The visual biology of Hawaiian reef fishes was explored by examining their eyes for spectral sensitivity of their visual pigments and for transmission of light through the ocular media to the retina. The spectral absorption curves for the visual pigments of 38 species of Hawaiian fish were recorded using microspectrophotometry. The peak absorption wavelength (lambda(max)) of the rods varied from 477-502 nm and the lambda(max) of individual species conformed closely to values for the same species previously reported using a whole retina extraction procedure. The visual pigments of single cone photoreceptors were categorized, dependent on their lambda(max)-values, as ultraviolet (347-376 nm), violet (398-431 nm) or blue (439-498 nm) sensitive cones. Eight species possessed ultraviolet-sensitive cones and 14 species violet-sensitive cones. Thus, 47% of the species examined displayed photosensitivity to the short-wavelength region of the spectrum. Both identical and nonidentical paired and double cones were found with blue sensitivity or green absorption peaks (> 500 nm). Spectrophotometry of the lens, cornea, and humors for 195 species from 49 families found that the spectral composition of the light transmitted to the retina was most often limited by the lens (73% of species examined). Except for two unusual species with humor-limited eyes, Acanthocybium solandri (Scombridae) and the priacanthid fish, Heteropriacanthus cruentatus, the remainder had corneal-limited eyes. The wavelength at which 50% of the light was blocked (T50) was classified according to a system modified from Douglas and McGuigan (1989) as Type I, T50 < = 355 nm, (32 species); Type IIa, 355 < T50 < = 380 nm (30 species); Type IIb, 380 < T50 405 nm (84 species). Possession of UV-transmitting ocular media follows both taxonomic and functional lines and, if the ecology of the species is considered, is correlated with the short-wavelength visual pigments found in the species. Three types of short-wavelength vision in fishes are hypothesized: UV-sensitive, UV-specialized, and violet-specialized. UV-sensitive eyes lack UV blockers (Type I and IIa) and can sense UV light with the secondary absorption peak or beta peak of their longer wavelength visual pigments but do not possess specialized UV receptor cells and, therefore, probably lack UV hue discrimination. UV-specialized eyes allow transmission of UV light to the retina (Type I and IIa) and also possess UV-sensitive cone receptors with peak absorption between 300 and 400 nm. Given the appropriate perceptual mechanisms, these species could possess true UV-color vision and hue discrimination. Violet-specialized eyes extend into Type IIb eyes and possess violet-sensitive cone cells. UV-sensitive eyes are found throughout the fishes from at least two species of sharks to modern bony fishes. Eyes with specialized short-wavelength sensitivity are common in tropical reef fishes and must be taken into consideration when performing research involving the visual perception systems of these fishes. Because most glass and plastics are UV-opaque, great care must be taken to ensure that aquarium dividers, specimen holding containers, etc., are UV-transparent or at least to report the types of materials in use.

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The radial undistortion model proposed by Fitzgibbon and the radial fundamental matrix were early steps to extend classical epipolar geometry to distorted cameras. Later minimal solvers have been proposed to find relative pose and radial distortion, given point correspondences between images. However, a big drawback of all these approaches is that they require the distortion center to be exactly known. In this paper we show how the distortion center can be absorbed into a new radial fundamental matrix. This new formulation is much more practical in reality as it allows also digital zoom, cropped images and camera-lens systems where the distortion center does not exactly coincide with the image center. In particular we start from the setting where only one of the two images contains radial distortion, analyze the structure of the particular radial fundamental matrix and show that the technique also generalizes to other linear multi-view relationships like trifocal tensor and homography. For the new radial fundamental matrix we propose different estimation algorithms from 9,10 and 11 points. We show how to extract the epipoles and prove the practical applicability on several epipolar geometry image pairs with strong distortion that - to the best of our knowledge - no other existing algorithm can handle properly.

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Background: Kidney stone is a major universal health problem, affecting 10% of the population worldwide. Percutaneous nephrolithotomy is a first-line and established procedure for disintegration and removal of renal stones. Its surgical success depends on the precise needle puncture of renal calyces, which remains the most challenging task for surgeons. This work describes and tests a new ultrasound based system to alert the surgeon when undesirable anatomical structures are in between the puncture path defined through a tracked needle. Methods: Two circular ultrasound transducers were built with a single 3.3-MHz piezoelectric ceramic PZT SN8, 25.4 mm of radius and resin-epoxy matching and backing layers. One matching layer was designed with a concave curvature to work as an acoustic lens with long focusing. The A-scan signals were filtered and processed to automatically detect reflected echoes. Results: The transducers were mapped in water tank and tested in a study involving 45 phantoms. Each phantom mimics different needle insertion trajectories with a percutaneous path length between 80 and 150 mm. Results showed that the beam cross-sectional area oscillates around the ceramics radius and it was possible to automatically detect echo signals in phantoms with length higher than 80 mm. Conclusions: This new solution may alert the surgeon about anatomical tissues changes during needle insertion, which may decrease the need of X-Ray radiation exposure and ultrasound image evaluation during percutaneous puncture.

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This study investigates Portuguese companies’ use of the Internet to communicate social responsibility information, and the factors that affect this use. It examines the characteristics of companies that influence the prominence of social responsibility information on the Internet. Firm-specific factors that explain SRD by companies operating in a European country in which capital market fund raising is not regarded to be an important source of financing are analysed. The results are interpreted through the lens of a “political economy” framework which combines stakeholder and legitimacy theories perspectives, according to which companies disclose social responsibility information to present a socially responsible image so that they can legitimise their behaviours to their stakeholder groups and influence the external perception of reputation. Results suggest that a theoretical framework combining stakeholder and legitimacy theories may provide an explanatory basis for SRD by Portuguese companies. However, this study does not provide us with enough evidence to determine that the prominence given to CSR activities by Portuguese companies in their websites is linked to relationships with their stakeholders

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Mestrado em Radiações Aplicadas às Tecnologias da Saúde. Área de especialização: Protecção Contra Radiações

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We are working on the confluence of knowledge management, organizational memory and emergent knowledge with the lens of complex adaptive systems. In order to be fundamentally sustainable organizations search for an adaptive need for managing ambidexterity of day-to-day work and innovation. An organization is an entity of a systemic nature, composed of groups of people who interact to achieve common objectives, making it necessary to capture, store and share interactions knowledge with the organization, this knowledge can be generated in intra-organizational or inter-organizational level. The organizations have organizational memory of knowledge of supported on the Information technology and systems. Each organization, especially in times of uncertainty and radical changes, to meet the demands of the environment, needs timely and sized knowledge on the basis of tacit and explicit. This sizing is a learning process resulting from the interaction that emerges from the relationship between the tacit and explicit knowledge and which we are framing within an approach of Complex Adaptive Systems. The use of complex adaptive systems for building the emerging interdependent relationship, will produce emergent knowledge that will improve the organization unique developing.

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Dissertação apresentada à Escola Superior de Educação de Lisboa para a obtenção de grau de mestre em Ciências da Educação, Especialização em Intervenção Precoce

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Este artigo foi uma das publicações resultantes do projeto financiado pela FCT "Música e Drama no 1º ciclo do Ensino básico – o caso da Região Autónoma da Madeira" (PTDC/CED/72112/2006).

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A study about the physical appearance of pre-photographic, photomechanical, photographic and digital positive reflective prints was made, relating the obtained images with the history, materials and technology used to create them. The studied samples are from the Image Permanence Institute (IPI) study collection. The digital images were obtained using a digital SLR on a copystand and a compound light microscope, with different lighting angles (0º, 45ºand 90º) and magnifications from overall views on the copystand down to a 20x objective lens on the microscope. Most of these images were originally created by IPI for www.digitalsamplebook.org, a web tool for teaching print identification, and will be used on the www.graphicsatlas.org website, along with textual information on identification, technology and history information about these reproduction processes.

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This paper applied MDS and Fourier transform to analyze different periods of the business cycle. With such purpose, four important stock market indexes (Dow Jones, Nasdaq, NYSE, S&P500) were studied over time. The analysis under the lens of the Fourier transform showed that the indexes have characteristics similar to those of fractional noise. By the other side, the analysis under the MDS lens identified patterns in the stock markets specific to each economic expansion period. Although the identification of patterns characteristic to each expansion period is interesting to practitioners (even if only in a posteriori fashion), further research should explore the meaning of such regularities and target to find a method to estimate future crisis.

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We report on a simple method to obtain surface gratings using a Michelson interferometer and femtosecond laser radiation. In the optical setup used, two parallel laser beams are generated using a beam splitter and then focused using the same focusing lens. An interference pattern is created in the focal plane of the focusing lens, which can be used to pattern the surface of materials. The main advantage of this method is that the optical paths difference of the interfering beams is independent of the distance between the beams. As a result, the fringes period can be varied without a need for major realignment of the optical system and the time coincidence between the interfering beams can be easily monitored. The potential of the method was demonstrated by patterning surface gratings with different periods on titanium surfaces in air.

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Lectins were labeled with fluorescein and tried as conjugates in the immunofluorescence (IP) test for the detection of IgM antibodies to T. gondii, in the diagnosis of acute toxoplasmosis. This approach was an attempt to find alternative reagents for anti-human IgM fluorescent conjugates (AHIgMFC), which contain quite frequently anaibcdies to toxoplasma, as contaminants, due to natural T. gondii infections among animals used for imunization. Lentil (Lens culinaris) lectin fluorescence conjugates (LcFC) provided most satisfactory results. The evaluation of LcFC carried out in a total of 179 sera from patients with acute and chronic toxoplasmosis, with non-related infections or healthy subjects, gave high values of relative efficiency, co-positivity and co-negativity indices, respectively 0.989, 0.969 and 1.000, in reference to the conventional AHIgMFC. Moreover, three batches of LcFC successively prepared gave reproducible test results. The advantage of LcFC as an alternative reagent for the serodiagnosis of acute toxoplasmosis is supported by practical aspects of its preparation.

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Introdução – Na correção de miopias elevadas, a cirurgia por implante de lente intraocular fáquica tem tido progressivamente uma maior adesão em relação à cirurgia por laser. Compara-se a acuidade visual (AV) antes e após a cirurgia implanto-refrativa, verificando-se a efetividade deste método no incremento da visão em miopias elevadas. Metodologia – Foram analisados, retrospetivamente, 70 olhos de 41 pacientes, com miopia elevada, entre os 20 e 50 anos, submetidos a cirurgia implanto-refrativa entre 2009 e 2012. Resultados – Um dia após cirurgia, 42,86% da amostra melhorou a AV, 34,29% manteve e 22,85% diminuiu. Após 30 dias observou-se um aumento generalizado da quantidade de visão, sendo que: 64,29% atingiu os 10/10 de AV, 24,29% alcançou entre 9/10-7/10 e 11,42% entre 6/10-4/10. Conclusão – Comprovou-se a efetividade desta técnica cirúrgica, verificando-se o aumento da AV em 52,86% da amostra.

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As formulações de cloreto de sódio 0,9%, são na sua grande maioria utilizadas com bastante frequência sobretudo na população pediátrica. Tanto os cuidadores como os próprios profissionais de saúde as reconhecem e avaliam como um componente essencial para os cuidados de saúde desta população. No entanto, o grave problema destas formulações reside no facto de muitos dos consumidores após a sua utilização apresentarem reacções adversas, que não são justificáveis se apenas da composição da formulação fizerem parte água purificada e cloreto de sódio. Assim deve ser tida em conta a composição de cada apresentação farmacêutica, a fim de se averiguar quanto à presença de conservantes potencialmente perigosos e para deste modo alertar os possíveis consumidores destes produtos. O principal objectivo deste estudo foi a análise e avaliação da rotulagem e folheto de instruções das formulações de cloreto de sódio 0,9% para aplicação tópica em pediatria, a fim de se averiguar a utilização de conservantes na sua formulação e por conseguinte a sua conformidade para comercialização. Com o auxílio de uma check-list, foram avaliadas 34 apresentações de venda livre de formulações de cloreto de sódio 0,9% para aplicação tópica, no período de Janeiro a Março de 2014. Das 34 apresentações farmacêuticas analisadas, apenas uma dasapresentações não se encontrava descrita como dispositivo médico, mas sim como produto cosmético. Contudo quanto à marcação CE de conformidade, esta encontrava-se devidamente aposta em 94% das apresentações. No que às indicações terapêuticas diz respeito e como seria expectável, na sua maioria estas apresentações destinam-se em 51% dos casos para utilização nasal e em 33% dos casos para utilização oftálmica, sendo o modo de apresentação em gotas (88%) o mais encontrado para comercialização. Quanto à utilização de conservantes, constatou-se uma grande omissão e alguma imprecisão quanto às informações contidas na rotulagem e/ou folheto de instruções das formulações analisadas, expondo assim os indivíduos mais susceptíveis e em especial a população pediátrica ao risco de reacções adversas e que por vezes podem ser fatais. Por outro lado também podem ocorrer complicações aquando do uso inadvertido destasformulações com conservantes, por portadores de lentes de contacto ou sem a devida esterilidade para utilização oftálmica. Assim apesar de o soro fisiológico não ser considerado um medicamento, mas sim um dispositivo médico, deve ser contudo utilizado com algumas precauções, sobretudo nesta população pediátrica e sempre que possível aconselhado por um profissional treinado e consciente da problemática que os conservantes usados nestas formulações podem causar quando utilizados indevidamente.