RESUMEN
Amplification of broadband frequency-modulated (FM) pulses in high-efficiency materials such as ytterbium-doped strontium fluorapatite results in significant gain narrowing, leading to reduced on-target bandwidths for beam smoothing and to conversion from frequency modulation to amplitude modulation (AM). To compensate for these effects, we have applied precision spectral sculpting, requiring both amplitude and phase shaping, to the amplification of broadband FM pulses in narrow-band gain media. We have demonstrated sculpting for centerline small-signal gains of 10(4), producing amplified pulses that have both sufficient bandwidths for on-target beam smoothing and temporal profiles that have no potentially damaging AM.
RESUMEN
Ytterbium-doped Sr(5)(PO(4))(3)F was successfully lased at 985 nm in quasi-cw mode with a slope efficiency of 74% and an absorbed threshold energy of 18 mJ. Q-switched slope efficiencies of 21% were obtained with a maximum energy of 9.4 mJ in 8.8-ns pulses.
RESUMEN
We report on the experimental measurement of the saturated gain of Yb(3+):Sr(5)(PO(4))(3)F at the 1047-nm laser line as a function of pump fluence and probe energy. The emission line was accurately modeled as a single homogeneous extraction, yielding values of 6.2 x 10(-20) cm(2) for the emission cross section and 3.3 J/cm(2) for the saturation fluence.
RESUMEN
The stimulated Raman-scattering (SRS) gain coefficient has been measured quantitatively for the first time to our knowledge in Yb:Sr(5)(PO(4))(3)F to be 1.23 ? 0.12 cm/GW at 1053 nm. These data, along with surface and bulk losses, feedback that is due to surface reflections, gain saturation, and bandwidth, have been applied to a quantitative model that predicts the effects of SRS within a laser amplifier system where the laser gain media show SRS gain. Limitations and impact to the laser amplifier performance are discussed, along with possible techniques to reduce SRS loss.
RESUMEN
Trimethylaminuria (TMAuria) (McKusick 602079) first described in 1970 is an autosomal recessive condition caused by a partial or total incapacity to catalyze the N-oxygenation of the odorous compound trimethylamine (TMA). The result is a severe body odor and associated psychosocial conditions. This inborn error of metabolism, previously thought to be rare, is now being increasingly detected in severe and milder presentations. Mutations of a phase 1 detoxicating gene, flavin-containing monooxygenase 3 (FMO3), have been shown to cause TMAuria. Herein we describe a cohort of individuals ascertained in North America with severe TMAuria, defined by a reduction of TMA oxidation below 50% of normal with genotype-phenotype correlations. We detected four new FMO3 mutations; two were missense (A52T and R387L), one was nonsense (E314X). The fourth allele is apparently composed of two relatively common polymorphisms (K158-G308) found in the general population. On the basis of this study we conclude that one common mutation and an increasing number of private mutations in individuals of different ethnic origins cause TMAuria in this cohort.
Asunto(s)
Errores Innatos del Metabolismo/genética , Metilaminas/orina , Oxigenasas/genética , Adulto , Alelos , Sustitución de Aminoácidos , Niño , Preescolar , Estudios de Cohortes , ADN/química , ADN/genética , Análisis Mutacional de ADN , Femenino , Genotipo , Humanos , Masculino , Errores Innatos del Metabolismo/orina , Persona de Mediana Edad , Mutación , Mutación Missense , América del Norte , Fenotipo , Mutación Puntual , Polimorfismo GenéticoRESUMEN
Lasing of Fe:ZnSe is demonstrated, for the first time to the authors' knowledge, for temperatures ranging from 15 to 180 K. The output wavelength of the Fe:ZnSe laser was observed to tune with temperature from 3.98mum at 15 K to 4.54mum at 180 K. With an Er:YAG laser operating at 2.698mum as the pump source, a maximum energy per pulse of 12muJ at 130 K was produced. Laser slope efficiencies of 3.2% at 19 K and 8.2% at 150 K were determined for an output coupling of 0.6%. A laser emission linewidth of 0.007mum at 3.98mum was measured at 15 K. Absorption and emission spectra and emission lifetimes for Fe:ZnSe are also discussed.
RESUMEN
Individuals with the recessive condition trimethylaminuria exhibit variation in metabolic detoxication of xenobiotics by hepatic flavin-containing monooxygenases. We show here that mutations in the human flavin-containing monooxygenase isoform 3 gene ( FMO3 ) impair N -oxygenation of xenobiotics and are responsible for the trimethylaminuria phenotype. Three disease-causing mutations in nine Australian-born probands have been identified which share a particular polymorphic haplotype. Nonsense and missense mutations are associated with a severe phenotype and are also implicated in impaired metabolism of other nitrogen- and sulfur-containing substrates including biogenic amines, both clinically and when mutated proteins expressed from cDNA are studied in vitro . These findings illustrate the critical role played by human FMO3 in the metabolism of xenobiotic substrates and endogenous amines.
Asunto(s)
Errores Innatos del Metabolismo/genética , Errores Innatos del Metabolismo/orina , Metilaminas/orina , Oxigenasas/genética , Oxigenasas/fisiología , Mutación Puntual/genética , Adolescente , Adulto , Niño , Preescolar , Clonación Molecular , ADN Complementario/biosíntesis , Haplotipos , Humanos , Persona de Mediana Edad , Fenotipo , Proteínas Recombinantes de Fusión/biosíntesisRESUMEN
The Glaucocystophyta (e.g., Cyanophora paradoxa) form a morphologically distinct group of photosynthetic protists that is primarily distinguished by its cyanelles (= plastids). To elucidate their evolutionary relationships, we determined nuclear-encoded small-subunit ribosomal RNA (SSU rRNA) coding regions for four taxa classified in the Glaucocystophyta (C. paradoxa, Glaucocystis nostochinearum, Glaucosphaera vacuolata, Gloeochaete wittrockiana; sensu Kies and Kremer), and these sequences were positioned within the eukaryotic phylogeny. Maximum likelihood, maximum-parsimony, and neighbor-joining phylogenetic analyses show that the Glaucocystophyta is a relatively late-diverging monophyletic assemblage within the "crown" group radiation that forms a sister group to cryptophyte algae. Glaucosphaera vacuolata is a red alga and lacks some cyanelle (e.g., bounding peptidoglycan wall) and host cell (e.g., cruciate flagellar roots) characters typical of glaucocystophytes. Our data are consistent with a monophyletic origin of the cyanelle in the glaucocystophytes. The distribution of photosynthetic taxa within the glaucocystophytes/cryptophytes and other lineages such as the filose amoebae/chlorarachniophytes and heterokont protists provide clues to the origin of plastids with four bounding membranes. We speculate that multiple, likely independent, secondary endosymbioses gave rise to these plastids.
Asunto(s)
Eucariontes/genética , Filogenia , ARN Ribosómico/genética , Rhodophyta/genéticaRESUMEN
We demonstrate temporal shaping of 0.35-microm-wavelength pulses produced by a third-harmonic conversion of the output from the Nova Nd:phosphate glass-laser amplifier system for use in inertial confinement fusion experiments. We describe the computer models used to calculate the pulse shape that is required as the input to the amplifier system, the experimental apparatus used to produce these pulses, and the high-power 0.35-microm shaped pulses produced in recent experiments.
RESUMEN
High-powered glass-laser systems with multiple beams, frequency-conversion capabilities, and pulseshaping flexibility have made numerous contributions to the understanding of inertial confinement fusion and related laser-plasma interactions. The Nova laser at Lawrence Livermore National Laboratory is the largest such laser facility. We have made improvements to the Nova amplifier system that permit increased power and energy output. We summarize the nonlinear effects that now limit Nova's performance and discuss power and energy produced at 1.05-, 0.53-, and 0.35-microm wavelengths, including the results with pulses temporally shaped to improve inertial confinement fusion target performance.
RESUMEN
To provide high-energy, high-power beams at short wavelengths for inertial-confinement fusion experiments, we routinely convert the 1.05-microm output of the Nova, Nd:phosphate-glass, laser system to its second- or third-harmonic wavelength. We describe the design and performance of the 3 x 3 arrays of potassium dihydrogen phosphate crystal plates used for type-II-type-II phase-matched harmonic conversion of the Nova 0.74-m diameter beams. We also describe an alternate type-I-type-II phasematching configuration that improves third-harmonic conversion efficiency. These arrays provide conversion of a Nova beam of up to 75% to the second harmonic and of up to 70% to the third harmonic.
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Small subunit rRNA sequences have been determined for 10 of the most clinically important pathogenic species of the yeast genus Candida (including Torulopsis [Candida] glabrata and Yarrowia [Candida] lipolytica) and for Hansenula polymorpha. Phylogenetic analyses of these sequences and those of Saccharomyces cerevisiae, Kluyveromyces marxianus var. lactis, and Aspergillus fumigatus indicate that Candida albicans, C. tropicalis, C. parapsilosis, and C. viswanathii form a subgroup within the genus. The remaining significant pathogen, T. glabrata, falls into a second, distinct subgroup and is specifically related to S. cerevisiae and more distantly related to C. kefyr (psuedotropicalis) and K. marxianus var. lactis. The 18S rRNA sequence of Y. lipolytica has evolved rapidly in relation to the other Candida sequences examined and appears to be only distantly related to them. As anticipated, species of several other genera appear to bear specific relationships to members of the genus Candida.
Asunto(s)
Candida/genética , ARN Ribosómico 18S/genética , Aspergillus fumigatus/genética , Secuencia de Bases , Evolución Biológica , ADN Ribosómico/genética , Datos de Secuencia Molecular , Oligonucleótidos/química , Pichia/genética , ARN de Hongos/genéticaRESUMEN
Abstract Vaginocervical stimulation of ovariectomized estradiol-primed ferrets (which are reflex ovulators) with a glass rod in the presence of a neck-gripping male induced an increase in plasma luteinizing hormone (LH) from undetectable levels (=0.50 ng/ml) before stimulation, to 2.4 +/- 0.43 ng/ml 75 min after stimulation (stimulated females). Forty-eight h after stimulation plasma LH returned to baseline levels (post-stimulated females). A significant decrease in the number of perikarya containing LH-releasing hormone (LHRH), detected by immunocytochemistry, was associated with the increase in plasma LH following stimulation. Approximately one half of the number of immunoreactive LHRH neurons (243+/-27) were detected in the forebrain of stimulated females, compared to those detected in the forebrain of post-stimulated animals (436 +/- 88) using antiserum AR 744. Equivalent results were obtained with a different antiserum (RM 1076) capable of detecting the extended decapeptide, or precursor, as well as partially or fully processed decapeptide. We conclude that controlled Vaginocervical stimulation of female ferrets evokes the release of LHRH as well as LH, depleting approximately 50% of the LHRH perikarya of detectable LHRH. Additionally, electron microscopy of LHRH perikarya of stimulated females revealed more Golgi complexes/cell compared to baseline females. We propose that Vaginocervical stimulation also augments the processing of extended precursor forms of LHRH to generate the decapeptide.