925 resultados para the symbolic order
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Mathematics Subject Class.: 33C10,33D60,26D15,33D05,33D15,33D90
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Mathematics Subject Classification: 26A33, 93B51, 93C95
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Binocular combination for first-order (luminancedefined) stimuli has been widely studied, but we know rather little about this binocular process for spatial modulations of contrast (second-order stimuli). We used phase-matching and amplitude-matching tasks to assess binocular combination of second-order phase and modulation depth simultaneously. With fixed modulation in one eye, we found that binocularly perceived phase was shifted, and perceived amplitude increased almost linearly as modulation depth in the other eye increased. At larger disparities, the phase shift was larger and the amplitude change was smaller. The degree of interocular correlation of the carriers had no influence. These results can be explained by an initial extraction of the contrast envelopes before binocular combination (consistent with the lack of dependence on carrier correlation) followed by a weighted linear summation of second-order modulations in which the weights (gains) for each eye are driven by the first-order carrier contrasts as previously found for first-order binocular combination. Perceived modulation depth fell markedly with increasing phase disparity unlike previous findings that perceived first-order contrast was almost independent of phase disparity. We present a simple revision to a widely used interocular gain-control theory that unifies first- and second-order binocular summation with a single principle-contrast-weighted summation-and we further elaborate the model for first-order combination. Conclusion: Second-order combination is controlled by first-order contrast.
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AMS subject classification: Primary 34A60, Secondary 49K24.
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2000 Mathematics Subject Classification: 62G32, 62G20.
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We present, for the first time, a detailed investigation of the impact of second order co-propagating Raman pumping on long-haul 100G WDM DP-QPSK coherent transmission of up to 7082 km using Raman fibre laser based configurations. Signal power and noise distributions along the fibre for each pumping scheme were characterised both numerically and experimentally. Based on these pumping schemes, the Q factor penalties versus co-pump power ratios were experimentally measured and quantified. A significant Q factor penalty of up to 4.15 dB was observed after 1666 km using symmetric bidirectional pumping, compared with counter-pumping only. Our results show that whilst using co-pumping minimises the intra-cavity signal power variation and amplification noise, the Q factor penalty with co-pumping was too great for any advantage to be seen. The relative intensity noise (RIN) characteristics of the induced fibre laser and the output signal, and the intra-cavity RF spectra of the fibre laser are also presented. We attribute the Q factor degradation to RIN induced penalty due to RIN being transferred from the first order fibre laser and second order co-pump to the signal. More importantly, there were two different fibre lasing regimes contributing to the amplification. It was random distributed feedback lasing when using counter-pumping only and conventional Fabry-Perot cavity lasing when using all bidirectional pumping schemes. This also results in significantly different performances due to different laser cavity lengths for these two classes of laser.
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In Sweden, during recent years, a new type of mixing protocol has been applied, in which the order of mixing is changed from the conventional method. Improved workability and diminished mixing and compaction energy needs have been important drivers for this. Considering that it is the mastic phase, which is modified by changing the mixing order, it provides an interesting case study for explaining the mechanisms of workability in connection with the mastic phase. To do so, an analytical viscosity framework was combined with a mixture morphology framework to upscale to the mixing level and tribology principles to explain the interaction between the mastic and the aggregates. From the mastic viscosity protocol, it was found that the mixing order significantly affects the resulting mastic viscosity. To analyse the effect of this on the workability and resulting mixture performance, X-ray computed tomography was used to analyse mixtures produced by the two different mixing sequences. Mechanical testing was utilised to determine the long-term mechanical performance. In this part of the study, mastic viscosity as a function of particle concentration and distribution was directly coupled to improved mixture workability and enhanced long-term performance.
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MSC 2010: 41A10, 41A15, 41A25, 41A36
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2000 Mathematics Subject Classification: 34C10, 34C15.
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2000 Mathematics Subject Classification: 39A10.
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A thulium-doped all-fiber laser passively mode-locked by the co-action of nonlinear polarization evolution and single-walled carbon nanotubes operating at 1860-1980 nm wavelength band is demonstrated. Pumped with the single-mode laser diode at 1.55 μm laser generates near 500-fs soliton pulses at repetition rate ranging from 6.3 to 72.5 MHz in single-pulse operation regime. Having 3-m long cavity average output power reached 300 mW, giving the peak power of 4.88 kW and the pulse energy of 2.93 nJ with slope efficiency higher than 30%. At a 21.6-m long ring cavity average output power of 117 mW is obtained, corresponding to the pulse energy up to 10.87 nJ and a pulse peak power of 21.7 kW, leading to the higher-order soliton generation.
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Controlling polymer thin-film morphology and crystallinity is crucial for a wide range of applications, particularly in thin-film organic electronic devices. In this work, the crystallization behavior of a model polymer, poly(ethylene oxide) (PEO), during spin-coating is studied. PEO films were spun-cast from solvents possessing different polarities (chloroform, THF, and methanol) and probed via in situ grazing incidence wide-angle X-ray scattering. The crystallization behavior was found to follow the solvent polarity order (where chloroform < THF < methanol) rather than the solubility order (where THF > chloroform > methanol). When spun-cast from nonpolar chloroform, crystallization largely followed Avrami kinetics, resulting in the formation of morphologies comprising large spherulites. PEO solutions cast from more polar solvents (THF and methanol) do not form well-defined highly crystalline morphologies and are largely amorphous with the presence of small crystalline regions. The difference in morphological development of PEO spun-cast from polar solvents is attributed to clustering phenomena that inhibit polymer crystallization. This work highlights the importance of considering individual components of polymer solubility, rather than simple total solubility, when designing processing routes for the generation of morphologies with optimum crystallinities or morphologies.
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This paper explores the concepts of Europe, Europeanism and European Union, their meaning to Hungarians, how people define them and how they relate to these concepts through the analysis of qualitative in-depth interviews. The main question is whether the discourse, expressing attitudes towards Europe and the European Union, are of symbolic or utilitarian character. The symbolic way to relate to the EU is based on principles, an ideological or an emotional approach of the subject, while the pragmatic or utilitarian logic is based on rational cost-benefit analysis. The main argument of this current paper is that the way Hungarians tend to relate to the EU is rather utilitarian and it is the utilitarian logic that represents the relevant frame to understand people’s attitudes on the subject.
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This exploratory descriptive study examined the factors that influence Registered Nurses (RNs) to return to school to pursue a Baccalaureate of Science in Nursing degree (BSN) and the factors that contribute to the decision to remain in school to complete the degree. Students (N = 226) enrolled in RN-BSN programs in three different universities in southeast Florida participated in the study by completing researcher developed questionnaires. The study group included 140 students who were newly enrolled in an RN-BSN program and 86 students who were preparing to graduate from an RN-BSN program. The instruments used in this study were two researcher developed questionnaires, the Corbett Nursing Educational Motivational Inventory - Form A (CNEMI-A), administered to the newly enrolled students, and the Corbett Nursing Educational Motivational Inventory - Form B (CNEMI-B), administered to the graduating students. The questionnaires included researcher-developed items in addition to items derived from a modified form of the Educational Participation Scale used by other researchers. Demographic data were also collected. Findings indicated that changes in health care, career goals, personal satisfaction, and flexible curriculum patterns are the major reasons why RNs return to school for the BSN. Less significant factors were social support, salary increase, and employer expectations. The factors considered most significant in the decision to remain in school to complete the degree were ranked in the following order: personal achievement, changes in health care, career change/advancement, enrollment options, faculty support, social support, and employer support. Implications for nurse educators related to the changing roles of RNs and the need to continue to assist RNs to adapt to new roles in health care. Recommendations for future research on RN-BSN nursing education included studies to identify the courses considered most useful by RN-BSN students as compared to courses considered repetitive of basic nursing programs. Studies were also recommended to examine the differences between the needs of RNs related to experience as an RN and recency of education. Additional studies were recommended to determine the feasibility of dual-enrollment ADN/BSN programs for last semester ADN students. ^
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The purpose of this study was to determine how dental and medical school deans perceived their own leadership styles and how many management/leadership perspectives they used when approaching a problem. A descriptive and correlational study was conducted which examined the leadership orientations or "frames" utilized by these deans. Four frames--the structural, the human resource, the political, and the symbolic--emerged from leadership studies which described the behavior of leaders in organizational actions and problem solving.^ Employing the repeated measures ANCOVA, it was found that there were no significant interactions between type of dean and perceptions or perspectives. However, the main effects of both leadership style perceptions and the use of perspectives were significant. This indicated that over the total sample of deans, both perceptions and perspectives were used differently; the deans perceived themselves and used perspectives the highest for the human resource frame and the lowest for the political frame. Also, dental deans' mean use overall of the four perspective frames was higher than the medical deans. In addition to the ANCOVA, t-tests performed on perceptions revealed that the deans perceived the frames differently in three human resource items. Pearson's correlations indicated that for the combined sample of deans, significant negative correlations existed when the human resource or symbolic frame was compared to the structural frame. All of the deans used multiple frames, allowing them to re-frame or combine frames according to the situation. ^