Scaling of decoherence in wide NMR quantum registers

Among the most important parameters for the usefulness of quantum computers are the size of the quantum register and the decoherence time for the quantum information. The decoherence time is expected to get shorter with the number of correlated qubits, but experimental data are only available for small numbers of qubits. Solid-state nuclear magnetic resonance allows one to correlate large numbers of qubits (several hundred) and measure their decoherence rates. We use a modified magnetic dipole-dipole interaction to correlate the proton spins in a solid sample and observe the decay of the resulting highly correlated states. By systematically varying the number of correlated spins, we measure the increase of the decoherence rate with the size of the quantum register.     

Roper–Suffridge extension operator and the lower bound for the distortion

Liczberski–Starkov gave a sharp lower bound for DΦ_n(f)(z) near the origin, where Φ_n is the Roper–Suffridge extension operator and f is a normalized convex mapping on the unit disk in C. They gave a conjecture that the sharp lower bound holds on the Euclidean unit ball Bⁿ in Cⁿ. In this paper, we will give a sharp lower bound on Bⁿ for a more general extension operator and for normalized univalent mappings f or normalized convex mappings f. We will give a lower bound for mappings f in a linear invariant family. We will also give a similar sharp lower bound on bounded convex complete Reinhardt domains in Cⁿ.     

Rapid and simple determination of doxycycline in serum by high-performance liquid chromatography. Application to particulate drug delivery systems

A simple, rapid and sensitive reversed-phase high-performance liquid chromatographic (HPLC) method for the measurement of doxycycline concentrations in both drug delivery systems (DDS) and serum extracted from mice after intraperitoneal (free drug) and intravenous (doxycycline administered in DDS) administration, has been developed. For the analysis of doxycycline in DDS, a known amount of particles was dissolved in chloroform and, after precipitating the polymer with methanol, the drug was assessed in the supernatant. For doxycycline quantification in microsamples of serum, proteins were precipitated with acetonitrile before chromatographic analysis. After centrifugation, the supernatant was mixed with a mixture of methanol and acetic acid (1:1) for analysis. The samples were chromatographed on a narrow-bore C18 column (Alltech Alltima 150 mm x 2.1 mm) using a mobile phase with 55% acetic acid (5%), 25% acetonitrile and 20% methanol. Doxycycline was detected 347 nm and the run time was 10 min. Linearity was confirmed in the concentration range 0.4-80 microg/ml for doxycycline quantification in serum and from 1 to 800 microg/ml for doxycycline extracted from DDS samples.     

Sensitivity to ALA-PDT of cell lines with different nitric oxide production and resistance to NO cytotoxicity

In this work, we studied the in vitro interactions between aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) and nitric oxide (NO), as well as the interactions between ALA, porphyrins and some NO donors and precursors. We employed three murine adenocarcinoma cell lines: LM2, which does not produce NO; LM3, which produces NO, and LM3-SNP, a variant of LM3 resistant to NO producing the same amount of NO as the parental. We did not find cross-resistance between NO-induced cytotoxicity and ALA-PDT. In spite of the lower porphyrin synthesis, LM2 cells show the highest sensitivity to ALA-PDT. However, we hypothesised that this is not related to the lack of endogenous NO production, because modulation of NO levels did not modify the response to PDT in any of the cell lines.

Two unexpected results were found: the enhancement of NO production from the donor sodium nitroprusside (SNP) induced by ALA in both cells and medium, and the inhibition by ALA of NO production from arginine. We also found that SNP strongly protected the cells from ALA-PDT by impairing porphyrin biosynthesis as a consequence of an inhibition of the enzyme ALA dehydratase. We were not able to evaluate the action of NO derived from SNP because of the unexpected porphyrin impairment. On the other hand, impairment of NO from Arginine driven by ALA, although not modulating in vitro the ALA-PDT response, by increasing in vivo blood flow, may be contributing to the mechanism of tumour cures.     

Fixed and pulsed gradient diffusion methods in low-field core analysis

We review diffusion-weighted relaxation protocols for two-dimensional diffusion/relaxation time (D, T(2)) distributions and their application to fluid-saturated sedimentary rocks at low fields typical of oil-well logging tools (< or = 2 MHz for 1H). Fixed field gradient (FFG) protocols may be implemented in logging tools and in the laboratory; there, pulsed field gradient (PFG) protocols are also available. In either category, direct or stimulated echoes may be used for the diffusion evolution periods. We compare the results of several variant FFG and PFG protocols obtained on liquids and two contrasting sedimentary rocks. For liquids and rocks of negligible internal gradients (g(int)), results are comparable, as expected, for all the studied protocols. For rocks of strong g(int), protocol-dependent artifacts are seen in the joint (D, T2) distributions, consistent with the effects of the internal fields. For laboratory petrophysics, the PFG methods offer several advantages: (a) significantly improved signal-to-noise ratio and acquisition times for repetitions over many samples; (b) freedom from heteronuclear contamination when fluorinated liquids are used in core holders; and (c) a palette of variants--one comparable with the FFG--for the study of rocks of significant g(int). Given suitable hardware, both PFG and FFG methods can be implemented in the same bench-top apparatus, providing a versatile test bed for application in a petrophysical laboratory.     

Intensity limits for propagation of 0.527 microm laser beams through large-scale-length plasmas for inertial confinement fusion

We have established the intensity limits for propagation of a frequency-doubled (2omega, 527 nm) high intensity interaction beam through an underdense large-scale-length plasma. We observe good beam transmission at laser intensities at or below 2x10(14) W/cm(2) and a strong reduction at intensities up to 10(15) W/cm(2) due to the onset of parametric scattering instabilities. We show that temporal beam smoothing by spectral dispersion allows a factor of 2 higher intensities while keeping the beam spray constant, which establishes frequency-doubled light as an option for ignition and burn in inertial confinement fusion experiments.     

Update on design simulations for NIF ignition targets, and the rollup of all specifications into an error budget

Targets intended to produce ignition on NIF are being simulated and the simulations are used to set specifications for target fabrication and other program elements. Recent design work has focused on designs that assume only 1.0 MJ of laser energy instead of the previous 1.6 MJ. To perform with less laser energy, the hohlraum has been redesigned to be more efficient than previously, and the capsules are slightly smaller. Three hohlraum designs are being examined: gas fill, SiO₂ foam fill, and SiO₂ lined. All have a cocktail wall, and shields mounted between the capsule and the laser entrance holes. Two capsule designs are being considered. One has a graded doped Be(Cu) ablator, and the other graded doped CH(Ge). Both can perform acceptably with recently demonstrated ice layer quality, and with recently demonstrated outer surface roughness. Complete tables of specifications are being prepared for both targets, to be completed this fiscal year. All the specifications are being rolled together into an error budget indicating adequate margin for ignition with the new designs. The dominant source of error is hohlraum asymmetry at intermediate modes 4–8, indicating the importance of experimental techniques to measure and control this asymmetry.     

Observation of saturation of energy transfer between copropagating beams in a flowing plasma

Experiments demonstrate energy and power transfer between copropagating, same frequency, beams crossing at a small angle in a plasma with a Mach 1 flow. The process is interpreted as amplification of the low intensity probe beam by the stimulated scatter of the high intensity pump beam. The observed probe amplification increases slowly with pump intensity and decreases with probe intensity, indicative of saturation limiting the energy and power transfer due to ion-wave nonlinearities and localized pump depletion. The results are consistent with numerical modeling including ion-wave nonlinearities.     

The influence of filler type on the separation properties of mixed-matrix membranes

Chitosan-based membranes filled with different metal oxide particles were prepared and their performance in ethanol dehydration process depending on the type of oxide and loading was discussed. For membrane preparation three oxides: TiO₂, Cr₂O₃ or Fe₃O₄ were selected. From experimental data suitable ethanol and water transport coefficients were evaluated. As shown in the results, applied fillers in different ways affect the separation properties. Presence of TiO₂ significantly affects the normalized total flux, increasing its value. On the other hand, addition of Fe₃O₄ influences most of all the separation factor, which is the among all investigated membranes. For membranes containing chromium(III) oxide as a filler, improvement in the separation properties is observed only in the case when the Cr₂O₃ content equals to 5 wt%. Above this concentration significant deterioration of separation properties is observed. The best performance has mixed-matrix membranes (MMMs) with magnetite, where the values of PSI are equal to 16.3 and 296.8 kg/m^?2 h µm for pristine and 15 wt% filler content, respectively.