2,008 research outputs found

    Oral transmucosal fentanyl

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    Non-Gaussian statistics of electrostatic fluctuations of hydration shells

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    We report the statistics of electric field fluctuations produced by SPC/E water inside a Kihara solute given as a hard-sphere core with a Lennard-Jones layer at its surface. The statistics of electric field fluctuations, obtained from numerical simulations, are studied as a function of the magnitude of a point dipole placed close to the solute-water interface. The free energy surface as a function of the electric field projected on the dipole direction shows a cross-over with the increasing dipole magnitude. While it is a single-well harmonic function at low dipole values, it becomes a double-well surface at intermediate dipole moment magnitudes, transforming to a single-well surface, with a non-zero minimum position, at still higher dipoles. A broad intermediate region where the interfacial waters fluctuate between the two minima is characterized by intense field fluctuations, with non-Gaussian statistics and the variance far exceeding the linear-response expectations. The excited state of the surface water is found to be lifted above the ground state by the energy required to break approximately two hydrogen bonds. This state is pulled down in energy by the external electric field of the solute dipole, making it readily accessible to thermal excitations. The excited state is a localized surface defect in the hydrogen-bond network creating a stress in the nearby network, but otherwise relatively localized in the region closest to the solute dipole

    Pilot Model Development and Human Manual Control Considerations for Helicopter Hover Displays

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    Head-down hover displays and instrument panels theoretically provide all necessary 2ight data information to control low-speed helicopter manoeuvring. However, past experiments have shown that head-down displays can incur high workload, control instability, and even loss of control when used as the sole 2ight data source. This paper investigates the reasons for this instability incurred by replacing good outside visuals with a head-down hover display and an instrument panel. A pilot model based on crossover theory is developed for a linear six-degree-of-freedom Bo. helicopter model. Utilising a target trajectory based on-theory and assuming perfect information availability, the developed model can perform the required manoeuvring task with a control time-delay stability margin of . s (with SAS) or . s (without SAS). Then, the actual information availability based on human perception methods and limitations is discussed. A pilot-in-the-loop experiment in the SIMONA Research Simulator qualitatively validates the developed pilot model for good outside visuals. However, the pilot model does not capture the added diZculties of having to utilise the hover display and instrument panel instead of good outside visuals; during the experiment, the task was impossible to complete with only these displays. This is likely caused by an increase in control time-delay, which in turn is caused by the loss of peripheral and flow 1eld information, a more abstract information representation compared to good outside visuals, and the fact that the pilot now needs to scan multiple displays to acquire all necessary 2ight state information. Improving head-down hover display symbology and scaling factors might rectify some, but probably not all of these effects.Control & Simulatio

    Global control and fast solid-state donor electron spin quantum computing

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    We propose a scheme for quantum information processing based on donor electron spins in semiconductors, with an architecture complementary to the original Kane proposal. We show that a naive implementation of electron spin qubits provides only modest improvement over the Kane scheme, however through the introduction of global gate control we are able to take full advantage of the fast electron evolution timescales. We estimate that the latent clock speed is 100-1000 times that of the nuclear spin quantum computer with the ratio T2/TopsT_{2}/T_{ops} approaching the 10610^{6} level.Comment: 9 pages, 9 figure

    Can we always get the entanglement entropy from the Kadanoff-Baym equations? The case of the T-matrix approximation

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    We study the time-dependent transmission of entanglement entropy through an out-of-equilibrium model interacting device in a quantum transport set-up. The dynamics is performed via the Kadanoff-Baym equations within many-body perturbation theory. The double occupancy <n^R↑n^R↓>< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >, needed to determine the entanglement entropy, is obtained from the equations of motion of the single-particle Green's function. A remarkable result of our calculations is that <n^R↑n^R↓>< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} > can become negative, thus not permitting to evaluate the entanglement entropy. This is a shortcoming of approximate, and yet conserving, many-body self-energies. Among the tested perturbation schemes, the TT-matrix approximation stands out for two reasons: it compares well to exact results in the low density regime and it always provides a non-negative <n^R↑n^R↓>< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >. For the second part of this statement, we give an analytical proof. Finally, the transmission of entanglement across the device is diminished by interactions but can be amplified by a current flowing through the system.Comment: 6 pages, 6 figure

    Second Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot

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    We demonstrate coherent driving of a single electron spin using second harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the anharmonic dot confining potential combined with a gradient in the transverse magnetic field dominates the second harmonic response. As expected, the Rabi frequency depends quadratically on the driving amplitude and the periodicity with respect to the phase of the drive is twice that of the fundamental harmonic. The maximum Rabi frequency observed for the second harmonic is just a factor of two lower than that achieved for the first harmonic when driving at the same power. Combined with the lower demands on microwave circuitry when operating at half the qubit frequency, these observations indicate that second harmonic driving can be a useful technique for future quantum computation architectures.Comment: 9 pages, 9 figure

    Learning from the early adopters: developing the digital practitioner

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    This paper explores how Sharpe and Beetham’s Digital Literacies Framework which was derived to model students’ digital literacies, can be applied to lecturers’ digital literacy practices. Data from a small-scale phenomenological study of higher education lecturers who used Web 2.0 in their teaching and learning practices are used to examine if this pyramid model represents their motivations for adopting technology-enhanced learning in their pedagogic practices. The paper argues that whilst Sharpe and Beetham’s model has utility in many regards, these lecturers were mainly motivated by the desire to achieve their pedagogic goals rather than by a desire to become a digital practitioner

    The use of growth models to evaluate the changing response to digestible lysine in high-lean growth gilts

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    Conventional response criteria for amino acid research include mean live weight gain and tissue accretion rates over a given weight interval. However, these methods fail to characterize the changing response of tissue accretion to dietary amino acids as body weight increases. For this reason, growth modeling was used to characterize the response to digestible lysine in two experiments (114 gilts each) from 80 to 160 lb and 160 to 300 lb, respectively. Corn-soybean meal diets were formulated to assure that lysine (.54 to 1.04% and .54 to .94% digestible lysine for Exp 1 and 2, respectively) was the first limiting amino acid. Analysis of variance was used to test linear and quadratic responses in cumulative weight gain on test as digestible lysine increased. A time by digestible lysine interaction was detected, indicating that a separate regression equation for each lysine level was necessary. In Exp. 1, ADG and carcass CP accretion were maximized for gilts fed 1.04, .94, and .84% digestible lysine from 80 to 100 lb, 100 to 120 lb, and 120 to 160 lb, respectively. Lipid accretion .74 to .84% digestible lysine. In Exp. 2, ADG was maximized by feeding .84% from 160 to 205 lb and .74% from 205 to 300 lb. Carcass CP accretion was maximized by feeding .94% digestible lysine, and lipid accretion was minimized for gilts fed .84% digestible lysine from 160 to 300 lb. If feeding graded levels of digestible lysine resulted in parallel lines for carcass protein accretion, mean values would result in accurate data evaluation. However, responses to digestible lysine changed over the feeding period. Therefore, the use of BW and compositional growth curves offers an innovative approach to more accurately characterize the growing pig\u27s response to increased digestible lysine.; Swine Day, Manhattan, KS, November 17, 199
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