3,992 research outputs found

    The me in memory:the role of the self in autobiographical memory development

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    This paper tests the hypothesis that self development plays a role in the offset of childhood amnesia; assessing the importance of both the capacity to anchor a memory to the self-concept, and the strength of the self-concept as an anchor. We demonstrate for the first time that the volume of 3- to 6-year-old’s specific autobiographical memories is predicted by both the volume of their self-knowledge, and their capacity for self-source monitoring within self-referencing paradigms (N =186). Moreover, there is a bidirectional relationship between self and memory, such that autobiographical memory mediates the link between self-source monitoring and self-knowledge. These predictive relationships suggests that the self memory system is active in early childhood

    PkANN - II. A non-linear matter power spectrum interpolator developed using artificial neural networks

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    In this paper we introduce PkANN, a freely available software package for interpolating the non-linear matter power spectrum, constructed using Artificial Neural Networks (ANNs). Previously, using Halofit to calculate matter power spectrum, we demonstrated that ANNs can make extremely quick and accurate predictions of the power spectrum. Now, using a suite of 6380 N-body simulations spanning 580 cosmologies, we train ANNs to predict the power spectrum over the cosmological parameter space spanning 3σ3\sigma confidence level (CL) around the concordance cosmology. When presented with a set of cosmological parameters (Ωmh2,Ωbh2,ns,w,σ8,∑mν\Omega_{\rm m} h^2, \Omega_{\rm b} h^2, n_s, w, \sigma_8, \sum m_\nu and redshift zz), the trained ANN interpolates the power spectrum for z≤2z\leq2 at sub-per cent accuracy for modes up to k≤0.9 hMpc−1k\leq0.9\,h\textrm{Mpc}^{-1}. PkANN is faster than computationally expensive N-body simulations, yet provides a worst-case error <1<1 per cent fit to the non-linear matter power spectrum deduced through N-body simulations. The overall precision of PkANN is set by the accuracy of our N-body simulations, at 5 per cent level for cosmological models with ∑mν<0.5\sum m_\nu<0.5 eV for all redshifts z≤2z\leq2. For models with ∑mν>0.5\sum m_\nu>0.5 eV, predictions are expected to be at 5 (10) per cent level for redshifts z>1z>1 (z≤1z\leq1). The PkANN interpolator may be freely downloaded from http://zuserver2.star.ucl.ac.uk/~fba/PkANNComment: 21 pages, 14 figures, 2 table

    Mission Life Thermal Analysis and Environment Correlation for the Lunar Reconnaissance Orbiter

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    Standard thermal analysis practices include stacking worst-case conditions including environmental heat loads, thermo-optical properties and orbital beta angles. This results in the design being driven by a few bounding thermal cases, although those cases may only represent a very small portion of the actual mission life. The NASA Goddard Space Flight Center Thermal Branch developed a procedure to predict the flight temperatures over the entire mission life, assuming a known beta angle progression, variation in the thermal environment, and a degradation rate in the coatings. This was applied to the Global Precipitation Measurement core spacecraft. In order to assess the validity of this process, this work applies the similar process to the Lunar Reconnaissance Orbiter. A flight-correlated thermal model was exercised to give predictions of the thermal performance over the mission life. These results were then compared against flight data from the first two years of the spacecraft s use. This is used to validate the process and to suggest possible improvements for future analyses

    Preparation of Dicke States in an Ion Chain

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    We have investigated theoretically and experimentally a method for preparing Dicke states in trapped atomic ions. We consider a linear chain of NN ion qubits that is prepared in a particular Fock state of motion, ∣m>|m>. The mm phonons are removed by applying a laser pulse globally to the NN qubits, and converting the motional excitation to mm flipped spins. The global nature of this pulse ensures that the mm flipped spins are shared by all the target ions in a state that is a close approximation to the Dicke state \D{N}{m}. We calculate numerically the fidelity limits of the protocol and find small deviations from the ideal state for m=1m = 1 and m=2m = 2. We have demonstrated the basic features of this protocol by preparing the state \D{2}{1} in two 25^{25}Mg+^+ target ions trapped simultaneously with an 27^{27}Al+^+ ancillary ion.Comment: 5 pages, 2 figure
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