932 resultados para ophthalmic optics and devices
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We examine the network benefits of various forms of nonlinearity compensation, showing that total network capacities that are more than double the capacity of a network with reaches determined by the Nonlinear-Shannon limit © 2015 OSA.
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In the digital age the internet and the ICT devices changed our daily life and routines. It means we couldn't live without these services and devices anywhere (work, home, holiday, etc.). It can be experienced in the tourism sector; digital contents become key tools in the tourism of the 21st century; they will be able to adapt the traditional tourist guide methodology to the applications running on novel digital devices. Tourists belong to a new generation, an "ICT generation" using innovative tools, a new info-media to communicate. A possible direction for tourism development is to use modern ICT systems and devices. Besides participating in classical tours guided by travel guides, there is a new opportunity for individual tourists to enjoy high quality ICT based guided walks prepared on the knowledge of travel guides. The main idea of the GUIDE@HAND service is to use reusable, and create new tourism contents for an advanced mobile device, in order to give a contemporary answer to traditional systems of tourism information, by developing new tourism services based on digital contents for innovative mobile applications. The service is based on a new concept of enhancing territorial heritage and values, through knowledge, innovation, languages and multilingual solutions going along with new tourists‟ “sensitiveness”.
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A high performance liquid-level sensor based on microstructured polymer optical fiber Bragg grating (mPOFBG) array sensors is reported in detail. The sensor sensitivity is found to be 98pm/cm of liquid, enhanced by more than a factor of 9 compared to a reported silica fiber-based sensor.
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We describe a parallel multi-threaded approach for high performance modelling of wide class of phenomena in ultrafast nonlinear optics. Specific implementation has been performed using the highly parallel capabilities of a programmable graphics processor. © 2011 SPIE.
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This study examines the effect of blood absorption on the endogenous fluorescence signal intensity of biological tissues. Experimental studies were conducted to identify these effects. To register the fluorescence intensity, the fluorescence spectroscopy method was employed. The intensity of the blood flow was measured by laser Doppler flowmetry. We proposed one possible implementation of the Monte Carlo method for the theoretical analysis of the effect of blood on the fluorescence signals. The simulation is constructed as a four-layer skin optical model based on the known optical parameters of the skin with different levels of blood supply. With the help of the simulation, we demonstrate how the level of blood supply can affect the appearance of the fluorescence spectra. In addition, to describe the properties of biological tissue, which may affect the fluorescence spectra, we turned to the method of diffuse reflectance spectroscopy (DRS). Using the spectral data provided by the DRS, the tissue attenuation effect can be extracted and used to correct the fluorescence spectra.
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Researchers conducted investigations to demonstrate the advantages of random distributed feedback fiber laser. Random lasers had advantages, such as simple technology that did not require a precise microcavity and low production cost. The properties of their output radiation were special in comparison to those of conventional lasers and they were characterized by complex features in the spatial, spectral, and time domains. The researchers demonstrated a new type of one-dimensional laser with random distributed feedback based on Rayleigh scattering (RS) that was presented in any transparent glass medium due to natural inhomogeneities of refractive index. The cylindrical fiber waveguide geometry provided transverse confinement, while the cavity was open in the longitudinal direction and did not include any regular point-action reflectors.
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Point-by-point fibre grating fabrication by femtosecond laser pulses requires tight focusing of the pulses into the core of the fibre. This condition is not easily satisfied in photonic crystal fibres (PCFs) due to the pulse scattering by the holes. In this letter, we present a numerical model of propagation of tightly focused laser beam through PCF in a typical experimental setup. We investigate impact of the numerical aperture of the beam and hole refractive index on the beam scattering and identify optimal conditions for relating the findings to the requirements of grating fabrication. The results explain and quantify recent experimental grating inscription techniques and are indicative of birefringence observed in long-period gratings written by femtosecond laser pulses. © 2010 Elsevier Ltd. All rights reserved.
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This paper will review the recent advances in the field of ultrashort pulse generation from optically pumped vertical-external-cavity surface-emitting lasers (OP-VECSELs). In this review, we will summarize the most significant results presented over the last 15 years, before highlighting recent breakthroughs related to mode-locked VECSELs by different research groups. Different mode-locking techniques for OP-VECSELs are described in detail. Previously, saturable absorbers, such as semiconductor saturable absorber mirrors—external, or internal as in mode-locked integrated external-cavity surface emitting lasers (MIXSEL)—, and recently, novel-material-based carbon-nanotube and graphene saturable absorbers have been employed. A new mode-locking method was presented and discussed in recent years. This method is referred to as self-mode-locking or saturable-absorber-free operation of mode-locked VECSELs. In this context, we particularly focus on achievements regarding self-mode-locking, which is considered a promising technique for the realization of high-power, compact, robust and cost-efficient ultrashort pulse lasers. To date, the presented mode-locking techniques have led to great enhancement in average powers, peak powers, and repetition rates that can be achieved with passively mode-locked VECSELs.
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Based on critical ideas from Michel Foucault, Benedict Anderson and Doris Sommer, this study analyzes the nation building function of the article of custom and manners and its literary mode "costumbrismo" in the Colombian literature of the 19th and beginning of the 20 th centuries. The discursive techniques and devices used in " costumbrismo" were put into effect by the Colombian intelligentsia to create a sense of national identity. Authors like, Ricardo Silva, José Caicedo Rojas, José David Guarín, Ignacio Gutiérrez Vergara, Eugenio Díaz, Juan de Dios Restrepo, José María Vergara y Vergara, Jorge Isaacs, José Eustaquio Palacios, José Manuel Marroquín, Tomás Carrasquilla, and José Eustasio Rivera became detailed observers that sometimes criticized and at other times just described customs and manners of different social classes and institutions. Through journalistic and literary discourse depicting regional customs and manners, these regionalist writers pretended to provide an objective and actual image of Colombian society, articulating, instead, a subjective message which expressed and reinforced their particular sense of nation based on a liberal or conservative political agenda. This discourse was used to shape the ideology of the republic thorough the idealization of a particular view of the nation.
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This work aims at studying the biographical mediation taken as the progress of people in formation process who develop a biographical work on their own experiences with the help of a former (PASSEGGI, 2006, 2011). The research was carried out on a curricular component from Curso de Formação Inicial e Continuada (initial and continuous process of formation of teachers) with teachers from public schools developed by Instituto Federal de Educação do Rio Grande do Norte (IFRN/ Ipanguaçu). The target audience featured diversity of professionals and experiences of formation. The general objective studied the potentials of procedures and devices used to mediate the reflection about the necessary knowledge to teaching practice based on their own experiences (auto-biographical) and the experience from the others (hetero-biographical). The study tried to respond to the following questions: how do teachers in formation relate themselves to the knowledge from experience? What procedures and devices contribute on the teachers‟ formation on the three different dimensions of biographical mediation (initiatory, maieutic, hermeneutics)? How to provide the auto-formation and hetero-formation? The theories and methods of this work are based on studies and researches that place the person in formation in the center of investigation and formation and analyze their reflective, re-inventive and self-re-inventive capacity. (FREIRE, 1987, 1996, 2001, 2011; JOSSO, 2008, 2010, 2012; DELORY-MONBERGER, 2006, 2008, 2012; CHARLLOT, 2000; CATANI, 2001; PASSEGGI, 2008; 2010; 2011; 2012). We selected six teachers who participate entirely on the meetings of the program. They discussed on the study topics, shared narrations that integrate their formation and the themes related to the course. The empirical material is composed by the narrations of the six participants and hearing boards done by themselves at the moment of the narration sharing process. The analysis followed three steps: a) the path of the program and the procedures of biographical mediation; b) the relations former/teacher on the three dimensions of biographical mediation; c) the hearing board as a device of biographical mediation. We concluded that the procedures and devices used for biographical mediation made possible specific learnings that are sources for the practice of initial and continuous teachers‟ formation, as well as for the formation of the former-researcher about the work with autobiographical narrations. Thus, it allow the co-investment of participants into the process of auto-formation and hetero-formation.
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The different characteristics and needs of mobile device users, the situations in which these devices are operated and the limitations and characteristics of these devices are all factors which influence usability and ergonomics; two elements highly required for achieving successful interaction between users and devices. This research aims to identify characteristics of interface design for apps in mobile device applications, focussing on design, visual publishing and content editing, and the actual process of creation of these interfaces, with a view to guarantee quality interaction through touch technology, in observance of service limitations, the opportunities offered by the devices and the application requirements. The study will examine the interface of the mobile device application titled “Brasil 247” which provides news broadcasts using the concept of usability and ergonomics mainly in the field of adaptation, searching and browsing informative articles, as well as clarifying the processes and techniques necessary to carry out interaction tests which seek to evaluate the usability of interface.
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In the case of Brazilian Psychiatric Reformation, mental health juvenile reveals itself as a great challenge, with major gaps in terms of needs, services and actions on mental illness in children and adolescents. This research is a qualitative study of descriptive and exploratory, having to analyze the actions and practices of mental health juvenile articulated between the Psychosocial Care Center juvenile (Caps i) and the basic care in Natal-RN, and specific, identify the limits and possibilities for an important precedent of the care network. After submission to the Research Ethics Committee (CEP) of the University Hospital Onofre Lopes (HUOL) of the Federal University of Rio Grande do Norte (UFRN) obtained approval contained in opinion number 777.067 / 2014. For the data collection, it was initially carried out a documentary research in the Municipal Health Department of Christmas about the phenomenon under study, and subsequently, applied semi-structured interviews with the subjects of the research, which were workers Caps i of Natal-RN. The analysis was woven as the thematic analysis technique, understood within the method of content analysis. The results and discussions were organized by categories and subcategories, namely: CATEGORY 1: Limits and weaknesses in the linkage between the Caps i and basic care, with the subcategories: 1.1 Lack of specialized services and devices articulators in network, 1.2 The diversity of situations in the demand juvenile assisted; CATEGORY 2: possibilities for an effective network, with the subcategory: 2.1 Intersectoral collaboration as a strategy for solving attention. The analysis revealed that the integration and coordination of mental health services juvenile and primary care in the city of Natal-RN, has incipient initiatives and/or inadequate for the resolvability intersectoral, where the devices of attention to health involved cannot establish bonds effective and long-lasting in the perspective of co-responsibility and sharing of care. On the other hand, it appears that the existing shares and practiced, configure an exercise in approximation to the dialog between mental health juvenile and basic care. It is highlighted that the shared care and the establishment of intersectoral collaboration within and outside of the health sector is possibility of facilitating the necessary dialog between the services and professionals involved, thus, enabling a better prospect of resolvability of the Network of Psychosocial Care for the youth in reality being investigated.
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We propose and examine an integrable system of nonlinear equations that generalizes the nonlinear Schrodinger equation to 2 + 1 dimensions. This integrable system of equations is a promising starting point to elaborate more accurate models in nonlinear optics and molecular systems within the continuum limit. The Lax pair for the system is derived after applying the singular manifold method. We also present an iterative procedure to construct the solutions from a seed solution. Solutions with one-, two-, and three-lump solitons are thoroughly discussed.
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Eigenmodes and dispersion curves in different configurations of synthetic photonic lattices are studied numerically. Eigenmodes localized on borders between areas with different optical potential are found. Stability of these eigenmodes against potential disturbances of different type is studied.
Constructing eigenmode excitation spectrum in synthetic photonic lattices using optical heterodyning
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A method based on optical heterodyning is proposed for measuring relative optical phases of pulses circulating in a synthetic photonic lattices. The knowledge of the phases can be further used for qualitative reconstruction of an eigenmode excitation spectrum in the synthetic photonic lattice.