Proton radiography of inertial fusion implosions

A distinctive way of quantitatively imaging inertial fusion implosions has resulted in the characterization of two different types of electromagnetic configurations and in the measurement of the temporal evolution of capsule size and areal density. Radiography with a pulsed, monoenergetic, isotropic proton source reveals field structures through deflection of proton trajectories, and areal densities are quantified through the energy lost by protons while traversing the plasma. The two field structures consist of (i) many radial filaments with complex striations and bifurcations, permeating the entire field of view, of magnetic field magnitude 60 tesla and (ii) a coherent, centrally directed electric field of order 10(9) volts per meter, seen in proximity to the capsule surface. Although the mechanism for generating these fields is unclear, their effect on implosion dynamics is potentially consequential.

Effect of laser intensity on fast-electron-beam divergence in solid-density plasmas

Metal foil targets were irradiated with 1 mum wavelength (lambda) laser pulses of 5 ps duration and focused intensities (I) of up to 4x10;{19} W cm;{-2}, giving values of both Ilambda;{2} and pulse duration comparable to those required for fast ignition inertial fusion. The divergence of the electrons accelerated into the target was determined from spatially resolved measurements of x-ray K_{alpha} emission and from transverse probing of the plasma formed on the back of the foils. Comparison of the divergence with other published data shows that it increases with Ilambda;{2} and is independent of pulse duration. Two-dimensional particle-in-cell simulations reproduce these results, indicating that it is a fundamental property of the laser-plasma interaction.

Shock ignition of thermonuclear fuel with high areal density

A novel method by C. Zhou and R. Betti [Bull. Am. Phys. Soc. 50, 140 (2005)] to assemble and ignite thermonuclear fuel is presented. Massive cryogenic shells are first imploded by direct laser light with a low implosion velocity and on a low adiabat leading to fuel assemblies with large areal densities. The assembled fuel is ignited from a central hot spot heated by the collision of a spherically convergent ignitor shock and the return shock. The resulting fuel assembly features a hot-spot pressure greater than the surrounding dense fuel pressure. Such a nonisobaric assembly requires a lower energy threshold for ignition than the conventional isobaric one. The ignitor shock can be launched by a spike in the laser power or by particle beams. The thermonuclear gain can be significantly larger than in conventional isobaric ignition for equal driver energy.

[The HIV infection - the limits of prevention concepts. Consideration with respect to responsibilities incumbent on the infected individual, politics and society at large]

Despite the introduction of campaigns to prevent the continued spread of HIV/AIDS in Germany, the number of annual firsttime HIV-diagnoses is continuing steadily. The concepts behind the current campaigns are largely based on models of New Public Health, of which social learning strategies are an essential element. The established personal and individual rights should be unimpeachable but the right not to know the status of HIV infection should be questioned for those people who spread their HIV infection intentionally and wilfully. Confronted with more than 10,000 people in Germany unconscious of their HIV infection, easy access to HIV testing and access of opportune therapy should be offered with the goal of reducing the number of new infections. Expanded strategies on the responsibility to one's personal health and that of the partner, understandable and adapted to special groups of the society, should be established and maintained at a high level of awareness. All measures must be performed voluntarily.

High-rhoR implosions for fast-ignition fuel assembly

Thick, 40 microm plastic shells filled with 25-35 atm of D2 or D3He were imploded on a low-adiabat (alpha approximately 1.3) and with a low-implosion velocity ( approximately 2 x 10(70 cm/s) on the OMEGA laser to generate massive cores of compressed plasma with high areal densities optimal for fast ignition. The targets are driven by 20-kJ relaxation adiabat-shaping laser pulses to keep the inner portion of the shell nearly Fermi degenerate. The measured kinetic energy downshift of proton spectra is in good agreement with the theoretical predictions yielding burn-averaged areal densities of 0.130+/-0.017 g/cm2 and peak rhoR during the burn of about 0.24+/-0.018 g/cm2, the largest rhoR measured on OMEGA to date. The same implosions with empty plastic shells are expected to reach 1.3 g/cm2 across the core (i.e., 2rhoR) enough to stop fast electrons with energies up to 4.5 MeV typical of fast ignition scenarios.

Observation of relativistic cross-phase modulation in high-intensity laser-plasma interactions

A nonlinear optical phenomenon, relativistic cross-phase modulation, is reported. A relativistically intense light beam (I = 1.3 x 10(18) W cm(-2), lambda = 1.05 microm) is experimentally observed to cause phase modulation of a lower intensity, copropagating light beam in a plasma. The latter beam is generated when the former undergoes the stimulated Raman forward scattering instability. The bandwidth of the Raman satellite is found to be broadened from 3.8-100 nm when the pump laser power is increased from 0.45-2.4 TW. A signature of relativistic cross-phase modulation, namely, asymmetric spectral broadening of the Raman signal, is observed at a pump power of 2.4 TW. The experimental cross-phase modulated spectra compared well with theoretical calculations. Applications to generation of high-power single-cycle pulses are also discussed.

Phase modulation of intense ultrashort laser pulses reflected from steep, dense plasmas

The phase modulation of intense ( I = 10(18) W/cm(2)) ultrashort laser pulses ( tau(p) = 70 fs) after reflection from steep, dense plasmas has been temporally resolved for the first time in particle-in-cell simulations. The position of the turning point from where the pulse reflects has been compared to the phase modulation, over a range of angles of incidence. At normal incidence or s polarization the phase modulation almost exactly represents the movement of the turning point due to the light pressure. As the angle of incidence is increased for p polarization, the simple Fresnel relationship between phase modulation and displacement of the reflection position, Delta phi(t) = -2k(0)Delta x(t)cos theta(0), increasingly breaks down.

High-efficiency dielectric reflection gratings: design, fabrication, and analysis

We report on reflection gratings produced entirely of dielectric materials. This gives the opportunity to enhance the laser damage threshold over that occurring in conventional metal gratings used for chirped-pulse-amplification, high-power lasers. The design of the system combines a dielectric mirror and a well-defined corrugated top layer to obtain optimum results. The rules that have to be considered for the design optimization are described. We optimized the parameters of a dielectric grating with a binary structure and theoretically obtained 100% reflectivity for the -1 order in the Littrow mounting for a 45 degrees angle of incidence. Subsequently we fabricated gratings by structuring a low-refractive-index top layer of a multilayer stack with electron-beam lithography. The multilayer system was fabricated by conventional sputtering techniques onto a flat fused-silica substrate. The parameters of the device were measured and controlled by light scatterometer equipment. We measured 97% diffraction efficiency in the -1 order and damage thresholds of 4.4 and 0.18 J/cm(2) with 5-ns and 1-ps laser pulses, respectively, at a wavelength of 532 nm in working conditions.

High-order harmonics from solid targets as a probe for high-density plasmas

The interaction of 100-fs Ti:sapphire laser pulses with thin foil targets was experimentally investigated at intensities exceeding 10(18) W/cm(2). High harmonics were observed in transmission through an overdense plasma in the direction of the incident beam. From the cutoff frequency of the harmonics an electron density of 1 x 10(24) cm(-3) is inferred, indicating a compression of the plasma by the ponderomotive force of the laser pulse.

Probing Collective Motions of Terminally Anchored Polymers

Polymer chains attached by one end to an impenetrable surface at high coverage exemplify a tethered layer of mesoscopic dimensions. At equilibrium, thermal fluctuations of the segment density profile of the brushlike layer reflect the tethered chain dynamics; the probing of these fluctuations by evanescent-wave dynamic light scattering is reported. By utilizing a set of terminally attached layers with thicknesses (L0) from 45 to 130 nanometers, it was found that there is a preferred wavelength of order L0 of these fluctuations with a concurrent slowing down of their thermal decay rate. This technique could open the route for the investigation of the largely unexplored area of polymer surface dynamics.

Pharmacokinetics of oxiracetam in elderly patients after 800 mg oral doses, comparison with non-geriatric healthy subjects

The pharmacokinetics of oxiracetam have been studied in eighteen elderly patients and in six healthy non-geriatric adults. A 800 mg single oral dose was administered in the morning of the first day and repeatedly, every 12 h, from day 2 evening to day 10 morning, to the elderly patients. The healthy non-geriatric adults were given a 800 mg single oral dose of oxiracetam. In healthy non-geriatric subjects after a single oral administration of 800 mg, the normalized plasma levels of oxiracetam for 1 mg/kg dose were similar to those already recorded after a 2000 mg single dose of oxiracetam. Therefore, there was no tendency towards non-linear pharmacokinetics of oxiracetam between 800 and 2000 mg single doses in healthy subjects. After the single oral dose, the mean area under the plasma concentration-time curve of oxiracetam in elderly patients was increased by a factor of two as compared to that observed in non-geriatric healthy subjects whereas the maximum concentration (Cmax) was almost not modified and slightly delayed. This can be explained by a slower absorption and elimination in the elderly patients. The highest oxiracetam levels were predominantly recorded in the oldest patients. The slower elimination (mean T1/2 = 12.3 h in elderly and 7.7 h in healthy subjects) could be attributed to a physiological decrease of the renal function. The volume of distribution was not significantly modified in the elderly patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of diclofenac and five metabolites after single doses in healthy volunteers and after repeated doses in patients

1. The kinetics of diclofenac (I) and five of its metabolites (II-VI) were investigated in three healthy volunteers and in six patients. Compounds I-VI were measured by capillary column gas chromatography in plasma and urine. 2. After a single 100 mg dose of diclofenac sodium to volunteers, the drug was absorbed rapidly and showed peak plasma levels of 10-12 nmol/g. The maximum concentrations of five metabolites were comparatively low (0.36-2.94 nmol/g). The mono- and dihydroxy metabolites (II-V) had apparent terminal half-lives similar to that of I (1-3 h), but the hydroxymethoxy metabolite (VI) had a half-life of about 80 h. Renal elimination of VI within 96 h was about 1% of dose and that of I-VI was 36% (free plus conjugated). 3. Following daily treatment with 2 x 75 mg of an experimental sustained release formulation to patients for 6-10 months, steady-state trough concentrations of I-V in plasma were low (average values: 0.23-0.57 nmol/g). The mean trough concentration of VI was comparatively higher at 3.69 +/- 0.91 nmol/g presumably reflecting its accumulation. Despite this it is unlikely to contribute to the drug's therapeutic activity, since it has been shown in laboratory tests to be devoid of anti-inflammatory activity.

Pharmacokinetics of clofazimine in healthy volunteers

The pharmacokinetics of clofazimine was evaluated in 12 healthy male volunteers following single and multiple oral doses of clofazimine. Six volunteers received a single dose of 200 mg together with food. A 200-mg dose was administered to three volunteers either with or without food. In a multiple-dose experiment, three volunteers were repeatedly dosed with 50 mg per day together with food for 8 days. Following a single oral dose of 200 mg, the mean peak plasma concentration of clofazimine was 861 +/- 289 pmol/g (+/- S.D., N = 6) after 8 hr (median). The mean terminal half-life was 10.6 +/- 4.0 days. Comparison of the bioavailability of clofazimine administered with or without food revealed a 60% higher mean area under the curve (AUC) value and a 30% higher mean maximum concentration (Cmax) value with food (N = 3). The median of times to peak (Tmax) was 8 hr with food and 12 hr without food. In the multiple-dose study, good agreement was found between the mean experimental plasma concentration values and the plasma concentration profile predicted from the single-dose pharmacokinetics. The elimination half-life calculated from the terminal phase of the individual profiles after the last dose was 8.8 +/- 1.0 days (+/- S.D., N = 3). The half-life obtained from the fitted mean multiple-dose profile was 10.5 days. The slow elimination of clofazimine has its implications for the treatment regimen in patients. To avoid the long-lasting accumulation toward the steady state, higher daily loading doses are recommended at the beginning of therapy followed by a daily maintenance dose.

The disposition and metabolism of 14C-oxprenolol.HCl in man

The disposition and metabolism of oxprenolol have been investigated in two healthy male volunteers, following a single 160 mg oral dose of racemic 14C-labelled oxprenolol. Absorption was rapid and complete. Peak blood concentrations of total radioactivity were 8.83 and 8.21 nmol X g-1 after 1 and 1.5 h in the two subjects. After 4 days 93.4 and 81.9% of the dose was excreted in urine, and a total of 96.6 and 84.5% found in the excreta. Mean peak blood concentrations of unchanged R(+)- and S(-)- oxprenolol were 0.83 and 0.81 nmol X g-1. Maximal concentrations of the glucuronides of the R(+)- and S(-)- isomers were 1.98 and 3.51 nmol X g-1. The mean half-lives of both oxprenolol enantiomers were 1.8 h, those of their glucuronides were 3.2 h (R(+] and 4.6 h (S(-]. Unchanged oxprenolol and the oxprenolol glucuronides constituted 11.4 and 66.5% of the area under the blood concentration-time curve (AUC, 0-24 h) of total radioactivity. The AUC-ratio of R(+) to S(-) was 1.19 for free oxprenolol and 0.36 for the glucuronides. Free metabolites II-X represented together 4.3% of 14C-AUC, and their glucuronides 15.2%. In urine, 1.8 and 1.0% of the total radioactivity was present as unchanged R(+)- and S(-)- oxprenolol, respectively. The glucuronides of the enantiomers accounted for 24.5 and 26.5%. The percentages of free 4- and 5-hydroxy oxprenolol were 0.7 and 2.4% while those of their glucuronides were 12.3 and 7.5%. Metabolites IV-X constituted together 6.2% in free form and 5.3% in conjugated form. In conclusion, the good mass balances in blood and urine has enabled the comprehensive and quantitative description of the metabolic fate of oxprenolol in man. Oxprenolol is extensively metabolized, direct O-glucuronidation being the major metabolic pathway and oxidative reactions minor ones. The disposition of the oxprenolol enantiomers revealed no remarkable stereoselective differences.

Disposition and pharmacokinetics of cadralazine and individual metabolites in man

The absorption, biotransformation and elimination of the antihypertensive drug cadralazine, 2-(3-[6-(2-hydroxypropyl)ethylamino]pyridazinyl)-ethylcarbazate , have been studied in two healthy male volunteers, following single 20 mg oral doses of the 14C-labelled preparation. Absorption was rapid and complete. In plasma total 14C-compounds reached maximum levels of 395 and 312 ng/g after 0.5 and 1.5 h in subject A and B, respectively. The levels rapidly declined to 3 and 6 ng/g after 24 h. Unchanged cadralazine constituted the major fraction, 72%, of the integrated plasma concentration (AUC, 0-24 h) of total radioactivity. As determined by an isotope dilution technique, about 1% of the AUC of plasma-14C was attributable to a pharmacologically active hydrazino-metabolite (IV) formed by decarbethoxylation and 2% to the acetylation product of the latter (V). Excretion of the radioactivity occured predominantly by the kidneys, 91 and 94% within 0-24 h in subject A and B. After 96 h 94 and 99% of the dose were found in the excreta. In the 0-48 h urine 73% of total 14C consisted of unchanged drug. The hydrazino-metabolite (IV) accounted for about 2% of urinary radioactivity, and two secondary products of the same pathway (II, V) for another 2%. Products of N-dealkylation (VI, VII) and C-oxidation (VIII) constituted together another 5%.

Gastrointestinal transit of Oros drug delivery systems in healthy volunteers: a short report

Transit times for oxprenolol and metoprolol Oros drug delivery systems through the gastrointestinal tract have been measured in 35 individuals in six separate studies. A total of 45 systems were recovered in a median time of 27.4 h; individual transit times varied from 5.1 to 58.3 h. The residual amount of drug in recovered systems was inversely related to transit time and corresponded closely with the amount estimated from in vitro dissolution profiles.

The metabolic fate of 14C-oxaprotiline X HCl in man. III. Stereospecific disposition

The disposition of the enantiomers of oxaprotiline has been investigated after single 100 mg oral doses of racemic 14C-labelled oxaprotiline X HCl in two healthy subjects. Absorption was complete. Peak blood concentrations of total 14C were 804 and 1010 ng equiv. g-1 after 4-6 h in the two subjects. After 9 days 85 and 80 per cent of the dose were excreted in urine, and a total of 93 and 87 per cent were found in the excreta. Mean peak blood concentrations of unchanged S(+)- and R(-)-oxaprotiline amounted to 25 and 10 ng g-1 before, and 474 and 422 ng g-1 after acid hydrolysis (free plus O-glucuronide). The mean blood half-lives of the S(+) and R(-) isomers were 22 and 23 h. Direct O-glucuronidation is the major metabolic pathway and N-demethylation a minor one. The former is more marked with the S(+) isomer and the latter with the R(-) isomer. For oxaprotiline, the AUC-ration of S(+) to R(-) was 2.2 before and 1.4 after hydrolysis. For desmethyl oxaprotiline the corresponding ration was 0.8 after hydrolysis. In urine, 0.8 and 0.5 per cent of total 14C were present as unchanged S(+)- and R(-)-oxaprotiline. After acid hydrolysis of the O-glucuronides, the enantiomers account for 44.7 and 37.1 per cent. The O-glucuronides of S(+)- and R(-)-desmethyl oxaprotiline account for 4.6 and 5.7 per cent.

Pharmacokinetics and dosage adjustment of cefotiam in renal impaired patients

The pharmacokinetics of cefotiam were investigated after intravenous administration of 1 g to 2 healthy volunteers with normal renal function and to 16 patients whose creatinine clearance ranged from 4.7 to 0.1 l/h (78 to 1.66 ml/min). The elimination half-life varied from 1.1 h in normal subjects to 13 h in patients and the total plasma clearance from 21 to 0.6 l/h (350 to 10 ml/min). The urinary recovery decreased from 62% of the dose in normal subjects to 1.1% in patients, and the renal clearance from 15 to 0.01 l/h (250 to 0.5 ml/min). Plasma and renal clearances of cefotiam correlated well with the creatinine clearance. The dosage schedule for cefotiam in patients with normal renal function can be used in the presence of renal failure when the creatinine clearance is equal to or greater than 1 l/h (16.6 ml/min). For patients whose creatinine clearance is less than 1 l/h, the dose must be decreased to 75% of that for a patient with normal renal function only when it is given every 6 or 8 h.