152,682 research outputs found
Implementing quantum logic gates with GRAPE: principles and practicalities
We briefly describe the use of GRAPE pulses to implement quantum logic gates
in NMR quantum computers, and discuss a range of simple extensions to the core
technique. We then consider a range of difficulties which can arise in
practical implementations of GRAPE sequences, reflecting non-idealities in the
experimental systems used.Comment: 15 pages rspublic including 4 figures. This is the original
manuscript preprint form which differs slightly from the final accepted
version (Phil Trans Roy Soc A in press
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Electrophysiological evidence for changes in attentional orienting and selection in functional somatic symptoms
Neurophysiology Objective: We investigated changes in attention mechanisms in people who report a high number of somatic symptoms which cannot be associated with a physical cause. Method: Based on scores on the Somatoform Disorder Questionnaire (SDQ-20; Nijenhuis et al., 1996) we compared two non-clinical groups, one with high symptoms on the SDQ-20 and a control group with low or no symptoms. We recorded EEG whilst participants performed an exogenous tactile attention task where they had to discriminate between tactile targets following a tactile cue to the same or opposite hand. Results: The neural marker of attentional orienting to the body, the Late Somatosensory Negativity (LSN), was diminished in the high symptoms group and attentional modulation of touch processing was prolonged at mid and enhanced at later latency stages in this group. Conclusion: These results confirm that attentional processes are altered in people with somatic symptoms, even in a non-clinical group. Furthermore, the observed pattern fits explanations of changes in prior beliefs or expectations leading to diminished amplitudes of the marker of attentional orienting to the body (i.e. the LSN) and enhanced attentional gain of touch processing. Significance: This study shows that high somatic symptoms are associated with neurocognitive attention changes
Nonlinear Sigma Model Analysis of the AFM Phase Transition of the Kondo Lattice
We have studied the antiferromagnetic quantum phase transition of a 2D
Kondo-Heisenberg square lattice using the non-linear sigma model. A
renormalization group analysis of the competing Kondo -- RKKY interaction was
carried out to 1-loop order in the expansion, and a new quantum
critical point is found, dominated by Kondo fluctuations. In addition, the
spin-wave velocity scales logarithmically near the new QCP, i.e breakdown of
hydrodynamic behavior. The results allow us to propose a new phase diagram near
the AFM fixed point of this 2D Kondo lattice model.Comment: 4 pages, 4 figure
Single stage experimental evaluation of compressor blading with slots and vortex generators. Part 2 - Data and performance for stage 5 without slots or vortex generators
Comparison performance data of compressor blading without slots or vortex generator
Observation requirements for unmanned planetary missions, part 2
Observation requirements for unmanned planetary mission
Single stage experimental evaluation of variable geometry guide vanes and stators. Part 1 - Analysis and design
Variable geometry concepts applied to guide vanes and stators in single stage compressor
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