5,273 research outputs found
Improved measurement of depth perception
Electromechanical system for Howard-Dolman device was developed. System is used for human depth perception measurements without tactual stimuli
Modulator for tone and binary signals
Tones and binary information are transmitted as phase variations on a carrier wave of constant amplitude and frequency. The carrier and tones are applied to a balanced modulator for deriving an output signal including a pair of sidebands relative to the carrier. The carrier is phase modulated by a digital signal so that it is + or - 90 deg out of phase with the predetermined phase of the carrier. The carrier is combined in an algebraic summing device with the phase modulated signal and the balanced modulator output signal. The output of the algebraic summing device is hard limited to derive a constant amplitude and frequency signal having very narrow bandwidth requirements. At a receiver, the tones and binary data are detected with a phase locked loop having a voltage controlled oscillator driving a pair of orthogonal detection channels
Microwave spectroscopy of a carbon nanotube charge qubit
Carbon nanotube quantum dots allow accurate control of electron charge, spin
and valley degrees of freedom in a material which is atomically perfect and can
be grown isotopically pure. These properties underlie the unique potential of
carbon nanotubes for quantum information processing, but developing nanotube
charge, spin, or spin-valley qubits requires efficient readout techniques as
well as understanding and extending quantum coherence in these devices. Here,
we report on microwave spectroscopy of a carbon nanotube charge qubit in which
quantum information is encoded in the spatial position of an electron. We
combine radio-frequency reflectometry measurements of the quantum capacitance
of the device with microwave manipulation to drive transitions between the
qubit states. This approach simplifies charge-state readout and allows us to
operate the device at an optimal point where the qubit is first-order
insensitive to charge noise. From these measurements, we are able to quantify
the degree of charge noise experienced by the qubit and obtain an inhomogeneous
charge coherence of 5 ns. We use a chopped microwave signal whose duty-cycle
period is varied to measure the decay of the qubit states, yielding a charge
relaxation time of 48 ns
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The evolution of rhythmic cognition: New perspectives and technologies in comparative research
Music is a pervasive phenomenon in human culture, and musical rhythm is virtually present in all musical traditions. Research on the evolution and cognitive underpinnings of rhythm can benefit from a number of approaches. We outline key concepts and definitions, allowing fine-grained analysis of rhythmic cognition in experimental studies. We advocate comparative animal research as a useful approach to answer questions about human music cognition and review experimental evidence from different species. Finally, we suggest future directions for research on the cognitive basis of rhythm. Apart from research in semi-natural setups, possibly allowed by âdrum set for chimpanzeesâ prototypes presented here for the first time, mathematical modeling and systematic use of circular statistics may allow promising advances
Memory based on abstraction for dynamic fitness functions
Copyright @ Springer-Verlag Berlin Heidelberg 2008.This paper proposes a memory scheme based on abstraction for evolutionary algorithms to address dynamic optimization problems. In this memory scheme, the memory does not store good solutions as themselves but as their abstraction, i.e., their approximate location in the search space. When the environment changes, the stored abstraction information is extracted to generate new individuals into the population. Experiments are carried out to validate the abstraction based memory scheme. The results show the efficiency of the abstraction based memory scheme for evolutionary algorithms in dynamic environments.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant No. EP/E060722/1
Differences in Interpersonal Values Among Students Involved in Volunteer Service
A study of college students involved m. community service volunteer activities found that students\u27 interpersonal values differed relative to whether they were involved through religious, Social Greek, or service organizations
Differences Among Community Service Volunteers, Extracurricular Volunteers, and Nonvolunteers on the College Campus
Students involved in volunteer community service activities display different demographic characteristics and inte1personal values than do other students
An evaluation of the post-ignition unblocking behavior of solid propellant aft-end ignition systems Final report
Determining postignition interactions between igniter and main motor flow by aft-end heated air simulation of solid propellant exhaus
An evaluation of aft-end ignition for solid propellant rocket motors
Performance evaluation of solid propellant rocket motor ignition to determine igniter design and parameters to avoid overpressurizatio
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