4,105 research outputs found

    ENVIRONMENT, EQUITY AND WATERSHED MANAGEMENT

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    This paper presents a methodology for incorporating environmental and social equity objectives in an economic analysis of watershed management. Empirical results indicate that restricting agricultural pollution notably increases farm costs. The equity objective also adversely affects economic efficiency, but the cost increase due to social equity is less significant.Environmental Economics and Policy,

    Multidisciplinary Design Optimization for Sonic Boom Mitigation

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    Automated, parallelized, time-efficient surface definition and grid generation and flow simulation methods are developed for sharp and accurate sonic boom signal computation in three dimensions in the near and mid-field of an aircraft using Euler/Full-Potential unstructured/structured computational fluid dynamics. The full-potential mid-field sonic boom prediction code is an accurate and efficient solver featuring automated grid generation, grid adaptation and shock fitting, and parallel processing. This program quickly marches the solution using a single nonlinear equation for large distances that cannot be covered with Euler solvers due to large memory and long computational time requirements. The solver takes into account variations in temperature and pressure with altitude. The far-field signal prediction is handled using the classical linear Thomas Waveform Parameter Method where the switching altitude from the nonlinear to linear prediction is determined by convergence of the ground signal pressure impulse value. This altitude is determined as r/L ≈ 10 from the source for a simple lifting wing, and r/L ≈ 40 for a real complex aircraft. Unstructured grid adaptation and shock fitting methodology developed for the near-field analysis employs an Hessian based anisotropic grid adaptation based on error equidistribution. A special field scalar is formulated to be used in the computation of the Hessian based error metric which enhances significantly the adaptation scheme for shocks. The entire cross-flow of a complex aircraft is resolved with high fidelity using only 500,000 grid nodes after only about 10 solution/adaptation cycles. Shock fitting is accomplished using Roe\u27s Flux-Difference Splitting scheme which is an approximate Riemann type solver and by proper alignment of the cell faces with respect to shock surfaces. Simple to complex real aircraft geometries are handled with no user-interference required making the simulation methods suitable tools for product design. The simulation tools are used to optimize three geometries for sonic boom mitigation. The first is a simple axisymmetric shape to be used as a generic nose component, the second is a delta wing with lift, and the third is a real aircraft with nose and wing optimization. The objectives are to minimize the pressure impulse or the peak pressure in the sonic boom signal, while keeping the drag penalty under feasible limits. The design parameters for the meridian profile of the nose shape are the lengths and the half-cone angles of the linear segments that make up the profile. The design parameters for the lifting wing are the dihedral angle, angle of attack, non-linear span-wise twist and camber distribution. The test-bed aircraft is the modified F-5E aircraft built by Northrop Grumman, designated the Shaped Sonic Boom Demonstrator. This aircraft is fitted with an optimized axisymmetric nose, and the wings are optimized to demonstrate optimization for sonic boom mitigation for a real aircraft. The final results predict 42% reduction in bow shock strength, 17% reduction in peak Δp, 22% reduction in pressure impulse, 10% reduction in foot print size, 24% reduction in inviscid drag, and no loss in lift for the optimized aircraft. Optimization is carried out using response surface methodology, and the design matrices are determined using standard DoE techniques for quadratic response modeling

    From visual perception to aesthetic appeal: Brain responses to aesthetically appealing natural landscape movies

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    During aesthetically appealing visual experiences, visual content provides a basis for computation of affectively tinged representations of aesthetic value. How this happens in the brain is largely unexplored. Using engaging video clips of natural landscapes, we tested whether cortical regions that respond to perceptual aspects of an environment (e.g., spatial layout, object content and motion) were directly modulated by rated aesthetic appeal. Twenty-four participants watched a series of videos of natural landscapes while being scanned using functional magnetic resonance imaging (fMRI) and reported both continuous ratings of enjoyment (during the videos) and overall aesthetic judgments (after each video). Although landscape videos engaged a greater expanse of high-level visual cortex compared to that observed for images of landscapes, independently localized category-selective visual regions (e.g., scene-selective parahippocampal place area and motion-selective hMT+) were not significantly modulated by aesthetic appeal. Rather, a whole-brain analysis revealed modulations by aesthetic appeal in ventral (collateral sulcus) and lateral (middle occipital sulcus, posterior middle temporal gyrus) clusters that were adjacent to scene and motion selective regions. These findings suggest that aesthetic appeal per se is not represented in well-characterized feature- and category-selective regions of visual cortex. Rather, we propose that the observed activations reflect a local transformation from a feature-based visual representation to a representation of “elemental affect,” computed through information-processing mechanisms that detect deviations from an observer’s expectations. Furthermore, we found modulation by aesthetic appeal in subcortical reward structures but not in regions of the default-mode network (DMN) nor orbitofrontal cortex, and only weak evidence for associated changes in functional connectivity. In contrast to other visual aesthetic domains, aesthetically appealing interactions with natural landscapes may rely more heavily on comparisons between ongoing stimulation and well-formed representations of the natural world, and less on top-down processes for resolving ambiguities or assessing self-relevance

    Differential Mobility Spectrometer with Spatial Ion Detector and Methods Related Thereto

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    Differential mobility spectrometer with spatial ion detector and methods related thereto are disclosed. The use of one or more spatial detector within differential mobility spectrometry can provide for the identification and separation of ions with similar mobility and mass

    The Most Common Behavioural Biases among Young Adults in Bristol, UK and Istanbul

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    According to traditional finance theories, individuals behave rationally and take financial decisions under this rationality. Contrary to traditional finance theories, behavioural finance states that individuals do not always act rationally because they are affected by emotions and feelings. Thus, behavioural finance can be defined as systematic errors that keep individuals away from rationality. The biases might cause unhelpful or even hurtful decisions. Therefore, a high level of behavioural biases might negatively affect the financial well-being of individuals. It is vital to investigate young adults’ financial behaviours as the future of the economies are influenced by their decisions. In this research, behavioural biases among young adults in Bristol, UK and Istanbul, Turkey, was examined to prevent young adults from making irrational financial decisions by identifying the most common behavioural biases. Thus, economies might be robust than today. According to result of this research, young adults have different behavioural biases depending on their culture. The most common biases among young adults in Bristol are over-optimism, anchoring, categorisation, conservatism, and the illusion of control while they are framing, cognitive dissonance, the illusion of knowledge and cue competition among young adults in Istanbul. These common behavioural biases that young adults in Bristol and Istanbul have to lead to many irrational financial decisions. It is not possible to reduce these behavioural biases by direct intervention, and for this, individuals need to be educated. Families may educate young adults about behavioural biases. After that rest of the education about behavioural biases may be given in the schools. Lastly, individuals should be informed about their behavioural biases and possible effects of these biases on their financial well-being

    View-tolerant face recognition and Hebbian learning imply mirror-symmetric neural tuning to head orientation

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    The primate brain contains a hierarchy of visual areas, dubbed the ventral stream, which rapidly computes object representations that are both specific for object identity and relatively robust against identity-preserving transformations like depth-rotations. Current computational models of object recognition, including recent deep learning networks, generate these properties through a hierarchy of alternating selectivity-increasing filtering and tolerance-increasing pooling operations, similar to simple-complex cells operations. While simulations of these models recapitulate the ventral stream's progression from early view-specific to late view-tolerant representations, they fail to generate the most salient property of the intermediate representation for faces found in the brain: mirror-symmetric tuning of the neural population to head orientation. Here we prove that a class of hierarchical architectures and a broad set of biologically plausible learning rules can provide approximate invariance at the top level of the network. While most of the learning rules do not yield mirror-symmetry in the mid-level representations, we characterize a specific biologically-plausible Hebb-type learning rule that is guaranteed to generate mirror-symmetric tuning to faces tuning at intermediate levels of the architecture

    "As an ethnic minority, you just have to work twice as hard." Experiences and motivation of ethnic minority students in medical education

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    INTRODUCTION: Adequate representation of ethnic minority groups in the medical workforce is crucial for ensuring equitable healthcare to diverse patient groups. This requires recruiting ethnic minority medical students and taking measures that enable them to complete their medical studies successfully. Grounded in self-determination theory and intersectionality, this paper explores the experiences of ethnic minority medical students across intersections with gender and other categories of difference and how these relate to students’ motivation. METHODS: An explorative, qualitative study was designed. Six focus groups were conducted with 26 ethnic minority students between December 2016 and May 2017. Thematic analysis was performed to identify, analyse and report themes within the data. RESULTS: The findings were categorized into three main themes: the role of autonomy in the formation of motivation, including students’ own study choice and the role of their family; interactions/‘othering’ in the learning environment, including feelings of not belonging; and intersection of ethnic minority background and gender with being ‘the other’, based on ethnicity. DISCUSSION: Ethnic minority students generally do not have a prior medical network and need role models to whom they can relate. Ensuring or even appointing more ethnic minority role models throughout the medical educational continuum—for example, specialists from ethnic minorities in teaching and/or mentoring roles in the education—and making them more visible to students is recommended. Moreover, a culture needs to be created in the educational environment in which students and staff can discuss their ethnicity-related differences. SUPPLEMENTARY INFORMATION: The online version of this article (10.1007/s40037-021-00679-4) contains supplementary material, which is available to authorized users
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