Performance analysis of interferometric noise due to unequally powered interferers in optical networks

Interferometric crosstalk has been identified as the cause of performance limits in future transparent all-optical networks. A large number of studies have been conducted on this phenomenon using a vast array of evaluation techniques. However, most major studies have considered that although the interfering terms may differ in number, the power contribution that they all make will be identical for all interfering terms. Although this situation is easy to analyze, it does not necessarily represent the situation that is likely to occur in a real network, which will be constructed of nodes with different degrees of connectivity, quite possibly from different vendors, and therefore with differing crosstalk characteristics. This paper describes a study on the impact of unequally powered interfering terms using a rigorous analysis technique. To validate the use of the chosen technique, the paper begins by bench-marking a number of common evaluation techniques against empirically derived, experimentally verified noise performance formulas

The propositional nature of human associative learning

The past 50 years have seen an accumulation of evidence suggesting that associative learning depends oil high-level cognitive processes that give rise to propositional knowledge. Yet, many learning theorists maintain a belief in a learning mechanism in which links between mental representations are formed automatically. We characterize and highlight the differences between the propositional and link approaches, and review the relevant empirical evidence. We conclude that learning is the consequence of propositional reasoning processes that cooperate with the unconscious processes involved in memory retrieval and perception. We argue that this new conceptual framework allows many of the important recent advances in associative learning research to be retained, but recast in a model that provides a firmer foundation for both immediate application and future research

Case Report: Infestation of Tunga penetrans in villages near Zomba Central Hospital

An outbreak of Tunga Penetrans (Jigger Flea) infestation affecting a number of villages near to a Central Hospital in Malawi is described. Due to the large number of affected individuals, high parasitic load, and extended duration of infection an alternative to the recommended approach of surgical removal of the flea was required. Benzyl benzoate paint and liquid paraffin had been used in local Primary Healthcare settings previously and topical treatment with antiparasitic agents has been advocated in the literature, particularly for severe infestation. Benzyl benzoate and liquid paraffin were applied topically to four adults with numerous jigger flea burrows, and their progress assessed regularly. After completion of 7 days of treatment patients noted that fleas were dislodging spontaneously, and that embedded parasites had not increased in size to the same extent that untreated fleas had in previous infestations. Following confirmation of the viability of its implementation in a resource-poor setting, this treatment regimen has subsequently been adopted by the local branch of the District Health Office for distribution to infected communities

A case study of argumentation at undergraduate level in history

This article examines two essays by undergraduate students in the first year of study in History at a university in the UK. It also draws on documentary evidence from the department in question and interviews with the students themselves to paint a picture of the way argumentation operates at this level. While no firm conclusions can be drawn, the evidence suggests a department with a high degree of awareness of the importance of argument and argumentation in studying History; and students who are aware and articulate about the problem facing them in constructing essays in the discipline. Suggestions are made about induction into the epistemological and argumentative demands of undergraduate study

Outcome predictability biases learning.

Much of contemporary associative learning research is focused on understanding how and when the associative history of cues affects later learning about those cues. Very little work has investigated the effects of the associative history of outcomes on human learning. Three experiments extended the "learned irrelevance" paradigm from the animal conditioning literature to examine the influence of an outcome's prior predictability on subsequent learning of relationships between cues and that outcome. All 3 experiments found evidence for the idea that learning is biased by the prior predictability of the outcome. Previously predictable outcomes were readily associated with novel predictive cues, whereas previously unpredictable outcomes were more readily associated with novel nonpredictive cues. This finding highlights the importance of considering the associative history of outcomes, as well as cues, when interpreting multistage designs. Associative and cognitive explanations of this certainty matching effect are discussed

A domain-specific language for the hybridization and static condensation of finite element methods

In this paper, we introduce a domain-specific language (DSL) for concisely expressing localized linear algebra on finite element tensors and its integration within a code-generation framework. This DSL is general enough to facilitate the automatic generation of element-based dense linear algebra kernels necessary for the implementation of static condensation methods and local solvers for a variety of problems. We demonstrate its use for the static condensation of continuous Galerkin problems, and systems arising from hybridizing finite element discretizations. We also describe how this DSL can be used to execute local post-processing procedures to construct superconvergent approximations to mixed problems. This work also features high-level implementations of static condensation and hybrid-mixed methods as preconditioners conforming to PETSc's interface for solving linear systems. These preconditioning interfaces provide reduced operators, which are obtained from locally assembled expressions, with the necessary context to specify full solver configurations on the resulting linear systems. We validate our implementations within the context of model second-order elliptic problems. Finally, we conclude with a performance comparison highlighting the use of a hybrid-mixed method as an efficient preconditioner in a semi-implicit method for the nonlinear rotating shallow water equations

Evidence of a Goal-Directed Process in Human Pavlovian-Instrumental Transfer

© 2017 APA, all rights reserved). Cues that signal rewards can motivate reward-seeking behaviors, even for outcomes that are not currently desired. Three experiments examined this phenomenon, using an outcome-selective Pavlovian-instrumental transfer (PIT) design and an outcome devaluation procedure. In Experiment 1, participants learned to perform one response to earn crisps points and another response to earn popcorn points. One outcome was then devalued by adulterating it to make it taste unpleasant. On test, overall response choice was biased toward the outcome that had not been devalued, indicating goal-directed control. Stimuli that signaled crisps and popcorn also biased instrumental response choice toward their respective outcomes (a PIT effect). Most importantly, the strength of this bias was not influenced by the devaluation manipulation. In contrast, Experiment 2 demonstrated that when stimuli signaled equal probability of the two outcomes, cue-elicited response choice was sensitive to the devaluation manipulation. Experiment 3 confirmed this conclusion by demonstrating a selective avoidance of the cued, devalued outcome. Together, these data support a goal-directed model of PIT in which expected outcome probability and value make independent contributions to response choice. (PsycINFO Database Recor

Women's negotiation of alternative sexualities in the Western Cape: A Cape Town case study

Masters of ArtThis mini thesis is an exploratory study of the lived experiences of bisexual and lesbian women in the Western Cape with regard to how they claim agency and negotiate their individual sexualities. Using mixed methodologies this study aims to look at the ways in which bisexual and lesbian women negotiate their sexuality in a landscape dominated by heterosexual discourses. Also considered are the contradictory ways in which these women assert their roles as lesbians and bisexual individuals and how these roles serve to simultaneously reinforce and challenge the dominant order of heterosexuality. The conflicting views of the respondents are documented which further demonstrates the complexities surrounding sexuality. This research identifies and explores both international and local research already conducted on alternative sexualities and address the lack of black researchers' conduct of these studies on the African continent. The study also records an acknowledgement of the researcher's reflection that she too holds contradictory views on some of these issues

Attention and associative learning in humans: An integrative review

This article presents a comprehensive survey of research concerning interactions between associative learning and attention in humans. Four main findings are described. First, attention is biased toward stimuli that predict their consequences reliably (learned predictiveness). This finding is consistent with the approach taken by Mackintosh (1975) in his attentional model of associative learning in nonhuman animals. Second, the strength of this attentional bias is modulated by the value of the outcome (learned value). That is, predictors of high-value outcomes receive especially high levels of attention. Third, the related but opposing idea that uncertainty may result in increased attention to stimuli (Pearce & Hall, 1980), receives less support. This suggests that hybrid models of associative learning, incorporating the mechanisms of both the Mackintosh and Pearce-Hall theories, may not be required to explain data from human participants. Rather, a simpler model, in which attention to stimuli is determined by how strongly they are associated with significant outcomes, goes a long way to account for the data on human attentional learning. The last main finding, and an exciting area for future research and theorizing, is that learned predictiveness and learned value modulate both deliberate attentional focus, and more automatic attentional capture. The automatic influence of learning on attention does not appear to fit the traditional view of attention as being either goal-directed or stimulus-driven. Rather, it suggests a new kind of “derived” attention