Rapid detection of incipient foil failure and remediation for longevity in repetitively pulsed, electron-beam-pumped excimer lasers for fusion research.

The use of an electron beam to pump an excimer laser has the advantage of being readily scalable to higher laser energies at high efficiency. Typically, a pulsed power driver generates the electron beam in a vacuum diode that consists of an electron emitter and a thin anode foil that holds the vacuum against the atmospheric-pressure laser gas. Even a miniscule leak in the anode foil can lead to an electrical breakdown in the vacuum diode, resulting in the destruction of the foil and evidence of the failure mechanism. The problem is even more onerous at the high voltage, high current, and pulse repetition frequencies needed for the large-area diodes used in excimer lasers for fusion research. Electra is one such laser used at the Naval Research Laboratory to develop excimer laser technologies for inertial fusion energy. To achieve longevity on Electra, it was necessary to instantly detect an incipient foil failure and halt the pulsed power drivers so the physical cause(s) could be studied. This rapid detection was accomplished using an optically filtered photodiode that senses the presence of argon emission from a Penning discharge vessel attached to the vacuum diodes. Details of this "Spectral Penning Leak Detector" device and its operation are presented. The diagnostics allowed the identification of a recurrent pinhole leak in the anode foil induced by cathode spots, which were created by electron emission from the foil during post-pulse voltage reversals. Eliminating the voltage reversals increased the continuous operation of the Electra laser from hundreds of shots to over 90 000 shots.

Radiotherapy in cancer and rheumathoid arthritis patients: cancer treatment or control of articular flares? We can achieve both.

OBJECTIVE: The study was aimed to investigate the role of radiotherapy (RT) as a risk factor for reactivation or worsening of symptoms in patients affected by rheumatoid arthritis (RA) PATIENTS AND METHODS: This is a single-center retrospective observational study on RA patients who developed cancer requiring RT during the course of the disease. The control group consisted of RA patients with cancer who did not undergo RT. In both groups, the disease activity was evaluated at baseline and at 6 and 12 months through the DAS28 index. A relapse was defined as an increase of >20% in DAS28. A radiotherapist evaluated total and daily doses and timing of radiation. Acute and late toxicity was defined as events occurring within 90 days from the start and more than 90 days after the completion of RT, respectively. RESULTS: Seventy-two RA patients (38F/34M; mean age: 70±9 years; mean disease duration: 13±9 years), 29 (40.2%) of whom received radiotherapy (mean age 72.9±9 years), were enrolled. The most frequent malignancies were breast (27.2%), thyroid (9.8%), and skin (7%). Between radio-treated and non-radio-treated patients, no significant differences in RA reactivation (6/29 vs. 17/43; p=0.12) or mean exacerbation time (6.7 ± 4.9 months compared to 6.4 ± 4.1 months; p=0.78) were found. Overall, RT was well tolerated with low rates of both acute and late toxicity. CONCLUSIONS: In RA patients, RT was well tolerated and not associated with an increased risk of articular flares. Properly designed prospective clinical studies with a larger number of patients should be performed to confirm these data.

Effects of a Preembedded Axial Magnetic Field on the Current Distribution in a Z-Pinch Implosion.

The fundamental physics of the magnetic field distribution in a plasma implosion with a preembedded magnetic field is investigated within a gas-puff Z pinch. Time and space resolved spectroscopy of the polarized Zeeman effect, applied for the first time, reveals the impact of a preembedded axial field on the evolution of the current distribution driven by a pulsed-power generator. The measurements show that the azimuthal magnetic field in the imploding plasma, even in the presence of a weak axial magnetic field, is substantially smaller than expected from the ratio of the driving current to the plasma radius. Much of the current flows at large radii through a slowly imploding, low-density plasma. Previously unpredicted observations in higher-power imploding-magnetized-plasma experiments, including recent, unexplained structures observed in the magnetized liner inertial fusion experiment, may be explained by the present discovery. The development of a force-free current configuration is suggested to explain this phenomenon.

Solution of the Noh problem with an arbitrary equation of state.

The classic self-similar solutions of the nonstationary compressible Euler equations obtained for a blast-wave propagation (Sedov, Taylor, and von Neumann), a shock-wave implosion (Guderley, Landau, and Stanyukovich), or an impulsive loading of a planar target (von Hoerner, Häfele, and Zel'dovich) have all been derived for a polytropic ideal gas. None of them can be generalized for a fluid with an arbitrary equation of state (EOS), such as the van der Waals EOS of a non-ideal-gas or a three-term EOS of a condensed material. We demonstrate here that the Noh accretion-shock problem is an exception. Its self-similar solutions exist in cylindrical and spherical geometry for fluids and materials with an arbitrary EOS. Such solutions for finite accretion-shock strength and nonuniform inflow velocity are constructed semianalytically with a model three-term equation of state that includes cold, thermal ion (lattice), and thermal electron contributions to the pressure and internal energy. Examples are presented for aluminum and copper. Other material- and EOS-specific semianalytic solutions of the Noh problem can be easily constructed using the same method for any material that in the pressure range of interest can be approximated as a dissipation-free fluid with an arbitrary equation of state.

The role of ethyl acrylate induced GSH depletion in the rodent forestomach and its impact on MTD and in vivo genotoxicity in developing an adverse outcome pathway (AOP).

Adverse outcome pathways (AOP) and mode of action (MOA) frameworks help evaluate the toxicity findings of animal studies and their relevance to humans. To effectively use these tools to improve hazard identification and risk assessments for ethyl acrylate (EA), knowledge gaps in metabolism and genotoxicity were identified and addressed. For EA, hypothesized early key events relate to its irritation potential: concentration dependent irritation and cytotoxicity, progressing to regenerative proliferation and forestomach carcinogenicity after repeated oral bolus application in rodents. The current research quantitated glutathione (GSH) depletion to assess a kinetically-derived maximum tolerated dose (MTD) in the target tissue and used this information to conduct an in vivo genotoxicity study using current methods. In the mouse forestomach, gavage doses of EA caused GSH depletion to 47% of control at 20 mg/kg and 28% at 100 mg/kg. Cellular redox changes and histopathology support saturation of metabolism and an MTD of ∼50 mg/kg. No increases in point mutations or deletions occurred in the stomach or liver following a 28 day treatment of gpt delta transgenic mice at gavage doses up to 50 mg/kg/day. These results provide valuable information for evaluating AOP molecular initiating events or MOA key events for EA and other GSH depleting materials.

Late recurrence (more than 10 years) in early (tumors equal to or smaller than 2 cm) breast cancer patients

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Ion temperature and hydrodynamic-energy measurements in a Z-pinch plasma at stagnation.

The time history of the local ion kinetic energy in a stagnating plasma was determined from Doppler-dominated line shapes. Using independent determination of the plasma properties for the same plasma region, the data allowed for inferring the time-dependent ion temperature, and for discriminating the temperature from the total ion kinetic energy. It is found that throughout most of the stagnation period the ion thermal energy constitutes a small fraction of the total ion kinetic energy; the latter is dominated by hydrodynamic motion. Both the ion hydrodynamic and thermal energies are observed to decrease to the electron thermal energy by the end of the stagnation period. It is confirmed that the total ion kinetic energy available at the stagnating plasma and the total radiation emitted are in balance, as obtained in our previous experiment. The dissipation time of the hydrodynamic energy thus appears to determine the duration (and power) of the K emission.

Using liquid and solid state NMR and photoluminescence to study the synthesis and solubility properties of amine capped silicon nanoparticles.

Water soluble silicon nanoparticles were prepared by the reaction of bromine terminated silicon nanoparticles with 3-(dimethylamino)propyl lithium and characterized with liquid and solid state nuclear magnetic resonance (NMR) and photoluminescence (PL) spectroscopies. The surface site dependent 29Si chemical shifts and the nuclear spin relaxation rates from an assortment of 1H-29Si heteronuclear solid state NMR experiments for the amine coated reaction product are consistent with both the 1H and 13C liquid state NMR results and routine transmission electron microscopy, ultra-violet/visible, and Fourier transform infrared measurements. PL was used to demonstrate the pH dependent solubility properties of the amine passivated silicon nanoparticles.

Computer modeling for optical waveguide sensors.

A two-layer model for the analysis of an optical waveguide chemical vapor sensor is developed using a program written for a low-cost (PC) computer, which takes into account a nonadsorbing glass-fluid interface, the number of optical reflections, and probe beam divergence, for angles of incidence which are skewed about the critical angle for total internal reflection. This model is applied in the analysis of condensed organic vapors employing an uncoated optical thin walled glass capillary device developed at NRL. Reasonable agreement is obtained between the experimental results and model predictions.

Reversible optical waveguide sensor for ammonia vapors.

A small glass capillary tube was fitted with a light-emitting diode and a phototransistor detector to form a multiple-reflecting optical waveguide device. When the capillary was coated with a thin solid film composed of an oxazine perchlorate dye, the device was demonstrated to be capable of reversibly sensing ammonia vapors. Ammoniavapor concentrations from 1000 parts in 10(6) (ppm) to less than 60 ppm were easily and reproducibly detected. A preliminary qualitative kinetic model is proposed to describe the vapor-film interaction.

Tumores malignos del tubo digestivo en la poblacion del Uruguay. Primera parte.Mortalidad segun localizacion y sexo.Anos 1963 y 1975. / Malignant tumors of the digestive tube in the population of Uruguay. First part. Mortality according to localization and sex. Years of 1963 and 1975

Se estudio la mortalidad en el Uruguay por tumores malignos del tubo digestivo, segun loalizacion y sexo en los anos 1963 y 1975, a partir de datos publicados por el Ministerio de Salud Publica. Se compararon los resultados obtenidos del ano 1975 con datos internacionales. La mortalidad por el total de tumores malignos del tubo digestivo, no vario en los dos anos estudiados, asi como tampoco la distribucion por sexo. En cambio, vario la mortalidad por localizacion; disminuyendo la mortalidad por tumor maligno de estomago y aumentando la mortalidad por tumor maligno de intestino, excepto recto. Comparando los datos del ano 1975 del Uruguay,con los de otras regiones, se observo inversion del orden de frecuencia en los canceres de esofago y recto en Uruguay, el cancer de esofago ocupa el tercer lugar y en otras regiones en cambio, ocupa el cuarto lugar: lo inverso ocurre con el cancer de recto. En el conocimiento de los autores, no existe hasta ahora ningun estudio similar

Tumores malignos del tubo digestivo en la poblacion del Uruguay. Segunda parte.Tumores malignos de esofago y estomago. / Malignant tumors of the digestive tube in the population of Uruguay.Second part Malignant tumors of esophagus and stomach

En la primera parte de este trabajo, "Tumores Malignos del tubo Digestivo en la Poblacion del Uruguay", se estudio el numero de muertes y las tasas de mortalidad por tumores malignos del tubo digestivo en el Uruguay, en los anos 1963 e 1975, y su incidencia en ambos sexos en cada uno de los grupos de edad en que se dividio la poblacion. Se compararon dichos valores con cifras y tasas de mortalidad de estudios realizados internacionalmente en otras naciones. En esta segunda parte, se estudian el numero de muertes y las tasas de mortalidad por tumores malignos de esofago y de estomago segun grupos de edad y sexo.Dicho estudio muestra que las cifras analizadas han permanecido invariables en los dos anos estudiados para los tumores malignos de esofago; en tanto que han disminuido, en 1975, para los tumores malignos de estomago. En ambos anos, y en ambos tipos de tumores, se verifica un predominio del sexo masculino sobre el femenino, y un aumento del numero de muertes y de las tasas de mortalidad, con la edad.Estos datos coinciden con los consultados en estudios internacionales

Tumores malignos del tubo digestivo en la poblacion del Uruguay. Tercera parte.Tumores malignos del intestino (excepto recto) y recto. / Malignant tumors of the digestive tube in the population of Uruguay. Third part.Malignant tumors of the intestines and rectum

En este trabajo fueron estudiados anteriormente, (primera parte) el numero de muertes y las tasas de mortalidad por tumores malignos del tubo digestivo en la poblacion del Uruguay para 1963 y 1975 y comparacion internacional. Se estudiaron luego (segunda parte), la mortalidad y las tasas de mortalidad por tumores malignos de esofago y estomago por grupos de edad y sexo, comparando los datos obtenidos para "otros paises" a nivel internacional. En esta tercera parte, se estudian el numero de muertes y las tasas de mortalidad por tumores malignos de intestino (excepto recto) y recto, segun grupos de edad y sexo. Estos estudios muestran, que en Uruguay los tumores malignos de intestino (excepto recto), presentan tasas similares para 1963 y 1975 en ambos sexos, observandose predominio del sexo femenino sobre el masculino en ambos anos. Para los tumores malignos de recto, se observa un descenso de las tasas de mortalidad en el ano 1975 con respecto a 1963, que se verifica en casi todas las edades y en ambos sexos manteniendose el predominio del sexo masculino sobre el femenino

Generation of intense blue tunable picosecond pulses by synchronous mixing of a Nd:glass laser with its sideband radiation.

The generation of blue tunable kilowatt picosecond light pulses by the up-conversion of the mode-locked Nd:glass laser pulses with its synchronously produced sideband radiation in an ADP crystal is reported.

Multiphoton excitation and emission from europium ions in aqueous solution.

Simultaneous emission induced by one- and two-photon absorption from the charge-transfer band from aqueous solutions of europium perchlorate pumped by a repetitively pulsed nitrogen laser have been detected. These processes were verified both through the measured fluorescence intensity as a function of the laser flux and from a qualitative analysis of the two overlapping characteristic broad emission spectra, which are dependent on the excitation wavelength. A theoretical fit could be made to the laser-power-dependence data, which gave a two-photon absorption coefficient of approximately 4 x 10(-49) cm(4) sec/photon-molecule for this system.