Two-Color Soft X-Ray Lasing in a High-Density Nickel-like Krypton Plasma.

We report evidence of strong lasing on the 4p-4s transition at 62.7 nm in nickel-like krypton occurring simultaneously with the usual 4d-4p lasing at 32.8 nm. The gain dynamics of both transitions were experimentally and numerically investigated and found comparable. The two-color amplifier was seeded by the same harmonic pulse, therefore producing a short-duration coherent two-color soft x-ray laser pulse. Both transitions offer similar prospects of pulse energy and duration and could lead to the delivery of intense and ultrashort two-color coherent soft x-ray pulses with a controllable delay.

Demonstration of a Circularly Polarized Plasma-Based Soft-X-Ray Laser.

We report the first experimental demonstration of a laser-driven circularly polarized soft-x-ray laser chain. It has been achieved by seeding a 32.8 nm Kr ix plasma amplifier with a high-order harmonic beam, which has been circularly polarized using a four-reflector polarizer. Our measurements testify that the amplified radiation maintains the initial polarization of the seed pulse in good agreement with our Maxwell-Bloch modeling. The resulting fully circular soft-x-ray laser beam exhibits a Gaussian profile and yields about 10^{10} photons per shot, fulfilling the requirements for laboratory-scale photon-demanding application experiments.

Fourier-limited seeded soft x-ray laser pulse.

We present what we believe to be the first measurement of the spectral properties of a soft x-ray laser seeded by a high-order harmonic beam. Using an interferometric method, the spectral profile of a seeded Ni-like krypton soft x-ray laser (32.8 nm) generated by optical field ionization has been experimentally determined, and the shortest possible pulse duration has been deduced. The source exhibits a Voigt spectral profile with an FWHM of 3.1+/-0.3 mA, leading to a Fourier-transform pulse duration of 4.7 ps. This value is comparable with the upper limit of the soft x-ray pulse duration determined by experimentally investigating the gain dynamics, from which we conclude that the source has reached the Fourier limit. The measured bandwidth is in good agreement with the predictions of a radiative transfer code, including gain line narrowing and saturation rebroadening.

Aberration-free laser beam in the soft x-ray range.

By seeding an optical-field-ionized population-inverted plasma amplifier with the 25th harmonic of an IR laser, we have achieved what we believe to be the first aberration-free laser beam in the soft x-ray spectral range. This laser emits within a cone of 1.34 mrad(1/e(2)) at a repetition rate of 10 Hz at a central wavelength of 32.8 nm. The beam exhibits a circular profile and wavefront distortions as low as lambda/17. A theoretical analysis of these results shows that this high beam quality is due to spatial filtering of the seed beam by the plasma amplifier aperture.

Crustal Layer of Seismic Velocity 6.9 to 7.6 Kilometers per Second under the Deep Oceans.

Refraction measurements made in the deep ocean between the Marshall and Hawaiian islands reveal a layer of seismic velocity 7.3 kilometers per second between the 6.8 kilometer per second oceanic crustal layer and the mantle. This layer, normally masked as a second arrival, is revealed by continuous air gun refraction data. The layer may be widespread in the deep oceans.

Electromagnetic instability in plasmas heated by a laser field.

Electromagnetic instability is investigated in homogeneous plasmas heated by a laser wave in the range α=v_{0}^{2}/v_{t}^{2}≤2, where v_{0} is the electron quiver velocity and v_{t} is the thermal velocity. The anisotropic electron distribution function that drives unstable quasistatic electromagnetic modes is calculated numerically with the Vlasov-Landau equation in the high ion charge number approximation. A dispersion relation of electromagnetic waves which accounts for further nonlinear terms on v_{0}^{2} from previous results is derived. In typical simulation with ion charge number Z=13, a temperature T=5keV, a density n=9.8×10^{20}cm^{-3}, and a laser wavelength λ_{laser}=1.06µm, growth rates larger than 10^{12}s^{-1} in the quasicollisionless wave-number range were found for α≥1. In the same physical conditions and in the mildly collisional range a growth rate about 10^{11}s^{-1} was also obtained. The extent of the growth wave-number region increases significantly with increasing α.

Anisotropic electron-distribution function in inverse-bremsstrahlung-heated plasmas.

The electron-distribution function in homogeneous plasmas heated by a high-frequency laser field is calculated in velocity space from the Vlasov-Landau equation. The kinetic model is valid for moderate laser intensity defined by the relevant parameter α=v_{0}^{2}/v_{t}^{2}<0.5 where v_{0} and v_{t} are the peak velocity of oscillation in the high-frequency electric field and the thermal velocity, respectively. The results obtained constitute an improvement of the results reported in the literature devoted to weak electric field intensities. The electron-distribution function is calculated solving the kinetic equation with the use of the Legendre polynomial expansion within the laser field dipole approximation. It results in an infinite set of equations for the isotropic component f_{0}(v) and the anisotropic components f_{n≥1}(v) that we have solved numerically with appropriate truncation. For the second anisotropy f_{2}(v), we found that its maximum increases from the weak electric field intensity (α<0.01) to a moderate one (α=0.5) by a factor f_{2max}(α=0.5)/f_{2max}(α=0.01)≈48. Applications to the radiation pressure, electromagnetic instabilities, and photoabsorption are also considered.

Phenytoin absorption from tube feedings.

Phenytoin, administered by suspension into a feeding tube through which continuous enteral feedings are being given, is very poorly absorbed. There appears to be very little information regarding this potentially serious problem in the general medical literature. Commonly used doses of phenytoin (300 to 500 mg/d) may result in almost undetectable serum levels. Therapeutic phenytoin levels may be obtained if a very large dose of the drug is given. Our patient required 1800 mg daily in two divided doses to get a serum phenytoin level of 9 micrograms/mL. Commonly used enteral feedings were being delivered by way of a continuous infusion pump. We found one enteral feeding product that did not severely impair the absorption of phenytoin. The mechanism by which enteral feedings impair phenytoin absorption is unknown.

2-substituted-1-naphthols as potent 5-lipoxygenase inhibitors with topical antiinflammatory activity.

The synthesis, biological evaluation, and structure-activity relationships of a series of 1-naphthols bearing carbon substituents at the 2-position are described. These compounds are potent inhibitors of the 5-lipoxygenase from RBL-1 cells and also inhibit bovine seminal vesicle cyclooxygenase. Structure-activity relationships for these two enzymes are different, implying specific enzyme inhibition rather than a nonspecific antioxidant effect. 2-(Aryl-methyl)-1-naphthols are among the most potent 5-lipoxygenase inhibitors reported (IC50 values generally 0.01-0.2 microM) and show excellent antiinflammatory potency in the mouse arachidonic acid ear edema model. To study the effects of structure on in vitro and in vivo activity, four general features of the molecules were varied: the 2-substituent, the 1-hydroxyl group, substitution on the naphthalene rings, and the 1,2-disubstituted naphthalene unit itself. 2-Benzyl-1-naphthol (5a, DuP 654) shows a very attractive profile of topical antiinflammatory activity and is currently in clinical trials as a topically applied antipsoriatic agent.

Philophthalmus gralli: chemosensitivity of miracidia.

The responses of Philophthalmus gralli miracidia to various chemicals stimulative to other miracidial species were tested by contact and return (CR) to agar blocks containing chemicals and aggregation near a point inoculum in phi-chambers. Of a series of amino acids, glutamic and aspartic acid elicited the greatest responses in both tests, which were similar to that observed with snail-conditioned water. Sialic, acetic, hydrochloric, and sulfuric acids gave high percent CR at all concentrations tested but required higher levels to stimulate a significant miracidial response in phi-chambers. Miracidia were slightly responsive to Mg++ and ammonia in CR tests but only showed a significant reaction to 1.0 mM ammonia in phi-chambers. Attachment responses to the agar blocks by miracidia were noted at the higher concentrations of all chemicals tested except MgSO4 and NH4Cl. At 25 and 50 mM H2SO4 and HCl, contact with the agar block proved lethal to the miracidia. Miracidial behavior was klinokinetic rather than chemotactic in both test systems.

Nonsymmetric laser-pulse propagation in capillary tubes with variable radius.

A model describing the nonsymmetrical laser-pulse propagation in capillary tubes with inner radius smoothly varying with the capillary length is proposed. Using this model, the use of capillaries with specially profiled entrance sections (particularly cone matching elements) for improving the coupling of the laser energy into a capillary and avoiding capillary ablation is analyzed. It is shown that cone entrances with a sufficiently small angle (α_{cone}≲10 mrad) help decrease the longitudinal energy flux and ablation of the entrance face of a capillary, but do not remove the requirements on the precision of laser-pulse focusing necessary to obtain regular laser fields, characterized by a symmetrical intensity distribution, centered on the capillary axis. To achieve regular laser fields without strong transverse gradients, the angle between the laser and capillary axes has to be smaller than 1 mrad for capillaries with an inner radius of the order of tens of microns.

Demonstration of a spatial filtering amplifier for high-order harmonics.

We report what is to our knowledge the first demonstration of spatial filtering of a high-order harmonic beam into a soft-x-ray laser plasma amplifier at 32.8 nm. After amplification the seed energy is enhanced by a factor of 50, and the beam profile of the amplified beam exhibits an Airy-like shape due to the spatial filtering by the optical field ionized plasma. Moreover, the transverse coherence of the spatially filtered amplified beam is strongly enhanced, resulting in the generation of a peak coherent power of 0.9 x 10(5) to 1.8 x 10(5) W.

Absolute time-resolved x-ray laser gain measurement.

We present the first direct measurement of the time evolution of the gain of a soft x-ray laser amplifier. The measurement is based on the injection of a seed pulse, obtained by high-order harmonic generation, into an x-ray laser medium. Strong amplification occurs when the seed pulse is synchronized with the gain period. By precisely varying the delay between the x-ray laser plasma creation and the seed pulse injection, the actual temporal evolution of the soft x-ray amplifier gain is obtained with a subpicosecond resolution.

Snatching capital campaign success from jaws of failure.

This article details the steps of one medical center which turned an "almost" $3.1 million capital campaign into a success. Leadership provided the steps to victory for a development director who stepped into a job with the high prospects of failure. In two years, he made his goal.

Thioridazine interferences with imipramine metabolism and measurement.

A case is presented in which toxic concentrations of imipramine (Tofranil) resulted from the co-administration of low-dose thioridazine (Mellaril). This probably occurred in an individual with genetically reduced capacity for oxidative drug metabolism, specifically via thioridazine's interference with the hepatic cytochrome P450IID6 isoenzyme (CYP2D6). In addition, coelution of thioridazine and its metabolites resulted in false elevations of imipramine and desipramine as measured by a common high-performance liquid chromatography (HPLC) method (cyanopropyl column). In contrast, an enzyme immunoassay (Abbott TDxFLx) and a second reference HPLC method (silica column) accurately resolved the analytes. This combination of psychiatric drugs is not uncommon in the pediatric population and is one of which both clinicians and laboratorians need to be aware. To the author's knowledge, this is the first report of interferences of thioridazine with both the metabolism and measurement of imipramine in a pediatric patient.