3,234,581 research outputs found

    Target Space Supersymmetric Sigma Model Calculations

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    We briefly review the covariant formulation of the Green-Schwarz superstring by Berkovits, and describe how a detailed tree-level and one-loop analysis of this model leads, for the first time, to a derivation of the low-energy effective action of the heterotic superstring while keeping target-space supersymmetry manifest. The resulting low-energy theory is old-minimal supergravity coupled to tensor multiplet. The dilaton is part of the compensator multiplet.Comment: LaTeX, 8 pages; to appear in proceedings of workshop on Gauge Theory, Applied Supersymmetry and Gauge Theory, Imperial College, July 5-10 199

    Model-based target sonification on mobile devices

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    We investigate the use of audio and haptic feedback to augment the display of a mobile device controlled by tilt input. We provide an example of this based on Doppler effects, which highlight the user's approach to a target, or a target's movement from the current state, in the same way we hear the pitch of a siren change as it passes us. Twelve participants practiced navigation/browsing a state-space that was displayed via audio and vibrotactile modalities. We implemented the experiment on a Pocket PC, with an accelerometer attached to the serial port and a headset attached to audio port. Users navigated through the environment by tilting the device. Feedback was provided via audio displayed via a headset, and by vibrotactile information displayed by a vibrotactile unit in the Pocket PC. Users selected targets placed randomly in the state-space, supported by combinations of audio, visual and vibrotactile cues. The speed of target acquisition and error rate were measured, and summary statistics on the acquisition trajectories were calculated. These data were used to compare different display combinations and configurations. The results in the paper quantified the changes brought by predictive or 'quickened' sonified displays in mobile, gestural interaction

    A heterotic sigma model with novel target geometry

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    We construct a (1,2) heterotic sigma model whose target space geometry consists of a transitive Lie algebroid with complex structure on a Kaehler manifold. We show that, under certain geometrical and topological conditions, there are two distinguished topological half--twists of the heterotic sigma model leading to A and B type half--topological models. Each of these models is characterized by the usual topological BRST operator, stemming from the heterotic (0,2) supersymmetry, and a second BRST operator anticommuting with the former, originating from the (1,0) supersymmetry. These BRST operators combined in a certain way provide each half--topological model with two inequivalent BRST structures and, correspondingly, two distinct perturbative chiral algebras and chiral rings. The latter are studied in detail and characterized geometrically in terms of Lie algebroid cohomology in the quasiclassical limit.Comment: 83 pages, no figures, 2 references adde

    A new mathematical model for radiation cell killing mechanism: Target cumulating model

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    There are numerous mathematical or statistical models have been given out for radiation cell killing mechanism. Unfortunately, none of the model could explain the mechanism perfectly. The more advanced model for it is still necessary to be researched. Following common assumption, a new theoretical model named "target cumulating" model is induced from the molecular and particle physics level. The result of theoretical calculation gives the equation of cell survival rate corresponding to delivered dose and other sensitivity parameters. In addition to fit the cell survival curve well, the new model showed advantages with comparing to previous models. Also, the new model predicts or explains some phenomenon that had been observed in laboratory (e.g. dose rate effect and low dose hypersensitivity)

    Target Saving In An Overlapping Generations Model

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    We examine a model in which the utility function has been engineered so that it is optimal for consumers to aim for a fixed target level of retirement resources. In this case consumption displays excess sensitivity to current income as well as perfect old age insurance. In an overlapping generations model, this leads naturally to multiple and unstable equilibria. Under static expectations, it also leads to a well-defined dynamics, including possible historical traps, implosions involving ever-diminishing capital stock and ever-increasing interest rates, and the feasibility of optimal one-time interventions.Targets, history, excess sensitivity, static expectations, rational expectations, uniqueness.

    Sigma-models having supermanifolds as target spaces

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    We study a topological sigma-model (AA-model) in the case when the target space is an (m0‚ą£m1m_0|m_1)-dimensional supermanifold. We prove under certain conditions that such a model is equivalent to an AA-model having an (m0‚ąím1m_0-m_1)-dimensional manifold as a target space. We use this result to prove that in the case when the target space of AA-model is a complete intersection in a toric manifold, this AA-model is equivalent to an AA-model having a toric supermanifold as a target space.Comment: 6 pages,late

    Optimal Inflation Target: Insights from an Agent-Based Model

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    Which level of inflation should Central Banks be targeting? We investigate this issue in the context of a simplified Agent Based Model of the economy. Depending on the value of the parameters that describe the behaviour of agents (in particular inflation anticipations), we find a rich variety of behaviour at the macro-level. Without any active monetary policy, our ABM economy can be in a high inflation/high output state, or in a low inflation/low output state. Hyper-inflation, deflation and "business cycles" between coexisting states are also found. We then introduce a Central Bank with a Taylor rule-based inflation target, and study the resulting aggregate variables. Our main result is that too-low inflation targets are in general detrimental to a CB-monitored economy. One symptom is a persistent under-realisation of inflation, perhaps similar to the current macroeconomic situation. Higher inflation targets are found to improve both unemployment and negative interest rate episodes. Our results are compared with the predictions of the standard DSGE model.Comment: 19 pages, 6 figures. The paper is under review for the online journal "Economics". The reviews are public at this link: http://www.economics-ejournal.org/economics/discussionpapers/2017-64 . This version has been modified and improved following the advice of the reviewers and commentator
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