947 resultados para 2-Stage Light Gas Gun


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1. Introduction: setting and problem definition 2. The Adaptation Pathway –2.1 Stage 1: appraising risks and opportunities •Step 1: Impact analysis •Step 2: Policy analysis •Step 3: Socio-institutional analysis –2.2 Stage 2: appraising and choosing adaptation opt ions •Step 4: identifying and prioritizing adaptation o ptions 3. Conclusions

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Mutations of von Hippel–Lindau disease (VHL) tumor-suppressor gene product (pVHL) are found in patients with dominant inherited VHL syndrome and in the vast majority of sporadic clear cell renal carcinomas. The function of the pVHL protein has not been clarified. pVHL has been shown to form a complex with elongin B and elongin C (VBC) and with cullin (CUL)-2. In light of the structural analogy of VBC-CUL-2 to SKP1-CUL-1-F-box ubiquitin ligases, the ubiquitin ligase activity of VBC-CUL-2 was examined in this study. We show that VBC-CUL-2 exhibits ubiquitin ligase activity, and we identified UbcH5a, b, and c, but not CDC34, as the ubiquitin-conjugating enzymes of the VBC-CUL-2 ubiquitin ligase. The protein Rbx1/ROC1 enhances ligase activity of VBC-CUL-2 as it does in the SKP1-CUL-1-F-box protein ligase complex. We also found that pVHL associates with two proteins, p100 and p220, which migrate at a similar molecular weight as two major bands in the ubiquitination assay. Furthermore, naturally occurring pVHL missense mutations, including mutants capable of forming a complex with elongin B–elongin C-CUL-2, fail to associate with p100 and p220 and cannot exhibit the E3 ligase activity. These results suggest that pVHL might be the substrate recognition subunit of the VBC-CUL-2 E3 ligase. This is also, to our knowledge, the first example of a human tumor-suppressor protein being directly involved in the ubiquitin conjugation system which leads to the targeted degradation of substrate proteins.

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CD1 is an MHC class I-like antigen-presenting molecule consisting of a heavy chain and β2-microglobulin light chain. The in vitro refolding of synthetic MHC class I molecules has always required the presence of ligand. We report here the use of a folding method using an immobilized chaperone fragment, a protein disulphide isomerase, and a peptidyl-prolyl cis-trans isomerase (oxidative refolding chromatography) for the fast and efficient assembly of ligand-free and ligand-associated CD1a and CD1b, starting with material synthesized in Escherichia coli. The results suggest that “empty” MHC class I-like molecules can assemble and remain stable at physiological temperatures in the absence of ligand. The use of oxidative refolding chromatography thus is extended to encompass complex multisubunit proteins and specifically to members of the extensive, functionally diverse and important immunoglobulin supergene family of proteins, including those for which a ligand has yet to be identified.

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Potato (Solanum tuberosum L.) single-node explants undergoing in vitro tuberization produced detectable amounts of ethylene throughout tuber development, and the resulting microtubers were completely dormant (endodormant) for at least 12 to 15 weeks. The rate of ethylene production by tuberizing explants was highest during the initial 2 weeks of in vitro culture and declined thereafter. Continuous exposure of developing microtubers to the noncompetitive ethylene antagonist AgNO3 via the culture medium resulted in a dose-dependent increase in precocious sprouting. The effect of AgNO3 on the premature loss of microtuber endodormancy was observed after 3 weeks of culture. Similarly, continuous exposure of developing microtubers to the competitive ethylene antagonist 2,5-norbornadiene (NBD) at concentrations of 2 mL/L (gas phase) or greater also resulted in a dose-dependent increase in premature sprouting. Exogenous ethylene reversed this response and inhibited the precocious sprouting of NBD-treated microtubers. NBD treatment was effective only when it was begun within 7 d of the start of in vitro explant culture. These results indicate that endogenous ethylene is essential for the full expression of potato microtuber endodormancy, and that its involvement may be restricted to the initial period of endodormancy development.

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We have previously shown that in the red alga Rhodella violacea, exposure to continuous low intensities of light 2 (green light) or near-saturating intensities of white light induces a ΔpH-dependent PSII fluorescence quenching. In this article we further characterize this fluorescence quenching by using white, saturating, multiturnover pulses. Even though the pulses are necessary to induce the ΔpH and the quenching, the development of the latter occurred in darkness and required several tens of seconds. In darkness or in the light in the presence of 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, the dissipation of the quenching was very slow (more than 15 min) due to a low consumption of the ΔpH, which corresponds to an inactive ATP synthase. In contrast, under far-red illumination or in the presence of 3-(3,4-dichlorophenyl)-1,1′-dimethylurea (only in light), the fluorescence quenching relaxed in a few seconds. The presence of N,N′-dicyclohexyl carbodiimide hindered this relaxation. We propose that the quenching relaxation is related to the consumption of ΔpH by ATP synthase, which remains active under conditions favoring pseudolinear and cyclic electron transfer.

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The quantity, type, and maturity of the organic matter of Quaternary and Tertiary sediments from the Japan Trench (DSDP Leg 56, Sites 434 and 436; and Leg 57, Sites 438, 439 and 440) were determined. The hydrocarbons in lipid extracts were analyzed by capillary- column gas chromatography and combined gas chromatography/ mass spectrometry. Kerogen concentrates were investigated by microscopy, and vitrinite-reflectance values were determined. Measured organic-carbon values were in the range of 0.13 to 1.00 per cent. Extract yields, however, were extremely low. Normalized to organic carbon, total extracts ranged from 4.1 to 15.7 mg/g Corg. Gas chromatography of non-aromatic hydrocarbons showed that all sediments, except one Oligocene sample, contained very immature, mainly terrigenous organic material. This was indicated by n-alkane maxima at C29 and C31 and high odd-carbon-number predominances. Unsaturated steroid hydrocarbons were found to be major cyclic compounds in lower- and middle-Miocene samples from the upper inner trench slope (Sites 438 and 439). Perylene was the dominating aromatic hydrocarbon in all but the Oligocene sample. Microscopy showed kerogens rich in terrigenous organic particles, with a major portion of recycled vitrinite. Nevertheless, almost all the liptinite particles appeared to be primary. This is a paradox, as the bulk of the samples were composed of hemipelagic mineral matter with a major siliceous biogenic (planktonic) component. A trend of reduced size and increased roundness can be seen for the vitrinite/ inertinite particles from west to east (from upper inner trench slope to outer trench slope). All sediments but one are relatively immature, with mean huminite-reflectance values (Ro)in the range of 0.30 to 0.45 per cent. The oldest and deepest sediment investigated, an Oligocene sandstone from Site 439, yielded a mean vitrinitereflectance value of 0.74 per cent and a mature n-alkane distribution. This sample may indicate a geothermal event in late Oligocene time. It failed to affect the overlying lower Miocene and may have been caused by an intrusion. Boulders of acidic igneous rocks in the Oligocene can be interpreted as witnesses of nearby volcanic activity accompanied by intrusions.

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Appendices of List of appendices in each volume, except volumes: 50, 63, 68, 78, 79, 85, 93, 101.

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v.1.Stage I.--v.2.Stage II.

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v. 1 Soldiers three; In black and white; The story of the Gadsbys; The phantom 'rickshaw and other tales; Wee Willie Winkie and other child stories.--v. 2 The light that failed; Plain tales from the hills.--v. 3 Mine own people; The courting of Dinah Shadd and other stories; American notes; Under the deodars and other tales; Departmental ditties; Barrack-room ballads and other verses.

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Background/Purpose: Several pull-through procedures are available for the surgical management of Hirschsprung's disease (HD) in children. The authors have adopted a laparoscopic approach since 1995, including laparoscopic Swenson procedure (LSw), both for one-stage primary and 2-stage secondary procedures. The aim of this study was to examine the role of LSw in children with HD in both primary and secondary procedures. Methods: From January 1995 to December 2001, 42 children with biopsy-proven HD underwent laparoscopic pull-through procedure for HD. This group included 29 children who underwent LSw, a detailed analysis of which forms the basis of this report. Results: Sixteen children underwent a single-stage neonatal LSw; the median weight of this group at the time of surgery was 3.2 kg and the median age was 5 days. Secondary LSw was performed in the remaining 13 children, which included 3 children with total colonic HD who underwent laparoscopic total colectomy and LSw. The median operating time was 105 minutes (range, 66 to 175 minutes). The median time to commence full diet was 48 hours (range, 24 to 86 hours), and median time to return to normal play and activity was 72 hours (range, 48 hours to 5 days). There was no difference in operating time between primary and secondary pull-through procedures. There were no intraoperative complications, and no patient required open conversion. Postoperative ileus was noted in 3 children and enterocolitis in 2. The median hospital stay was 4 days (range, 2 to 6 days). Follow-up was between 6 months to 7 years with a median follow-up of 2.2 years. At follow-up, 2 children required laparoscopic antegrade continence enema procedure. A satisfactory continence was noted in 15 of the 19 children who were older than 3 years at the time of last follow-up. Conclusions: LSw seems to be a suitable procedure for laparoscopic management of HD in children. LSw is safe and effective, both for primary and secondary type of pull-through procedures, with good short-term results.

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[GRAPHICS] The major cuticular hydrocarbons from the cane beetle species Antitrogus parvulus are 4,6,8,10,16-penta- and 4,6,8,10,16,18-hexamethyldocosanes, I and 2, respectively. Stereoisomers of 2,4,6,8-tetramethylundecanal of established relative stereochemistry were derived from 2,4,6-trimethylphenol and were then coupled with appropriate methyl-substituted phosphoranes 62 and 25 to furnish alkenes, which on reduction provided diastereomers of I and 2, respectively. Capillary gas chromatography, mass spectrometry, and high resolution C-13 NMR spectroscopy confirmed 1 as either 84a or 84b and 2 as either 15a or 15b. The novelty of these structures and their relative stereochemistry is briefly related to polyketide assembly.

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Edges are key points of information in visual scenes. One important class of models supposes that edges correspond to the steepest parts of the luminance profile, implying that they can be found as peaks and troughs in the response of a gradient (1st derivative) filter, or as zero-crossings in the 2nd derivative (ZCs). We tested those ideas using a stimulus that has no local peaks of gradient and no ZCs, at any scale. The stimulus profile is analogous to the Mach ramp, but it is the luminance gradient (not the absolute luminance) that increases as a linear ramp between two plateaux; the luminance profile is a blurred triangle-wave. For all image-blurs tested, observers marked edges at or close to the corner points in the gradient profile, even though these were not gradient maxima. These Mach edges correspond to peaks and troughs in the 3rd derivative. Thus Mach edges are inconsistent with many standard edge-detection schemes, but are nicely predicted by a recent model that finds edge points with a 2-stage sequence of 1st then 2nd derivative operators, each followed by a half-wave rectifier.

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We report all-fiber polarization interference filters, known as Lyot and Lyot-Ohman filters, based on alternative concatenation of UV-inscribed fiber gratings with structure tilted at 45° and polarization maintaining (PM) fiber cavities. Such filters generate comb-like transmission of linear polarization output. The free spectral range (FSR) of a single-stage (Lyot) filter is PM fiber cavity length dependent, as a 20 cm long cavity showed a 26.6 nm FSR while the 40 cm one exhibited a 14.8 nm FSR. Furthermore, we have theoretically and experimentally demonstrated all-fiber 2-stage and 3-stage Lyot-Ohman filters, giving more freedom in tailoring the transmission characteristics.

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Visual perception is dependent on both light transmission through the eye and neuronal conduction through the visual pathway. Advances in clinical diagnostics and treatment modalities over recent years have increased the opportunities to improve the optical path and retinal image quality. Higher order aberrations and retinal straylight are two major factors that influence light transmission through the eye and ultimately, visual outcome. Recent technological advancements have brought these important factors into the clinical domain, however the potential applications of these tools and considerations regarding interpretation of data are much underestimated. The purpose of this thesis was to validate and optimise wavefront analysers and a new clinical tool for the objective evaluation of intraocular scatter. The application of these methods in a clinical setting involving a range of conditions was also explored. The work was divided into two principal sections: 1. Wavefront Aberrometry: optimisation, validation and clinical application The main findings of this work were: • Observer manipulation of the aberrometer increases variability by a factor of 3. • Ocular misalignment can profoundly affect reliability, notably for off-axis aberrations. • Aberrations measured with wavefront analysers using different principles are not interchangeable, with poor relationships and significant differences between values. • Instrument myopia of around 0.30D is induced when performing wavefront analysis in non-cyclopleged eyes; values can be as high as 3D, being higher as the baseline level of myopia decreases. Associated accommodation changes may result in relevant changes to the aberration profile, particularly with respect to spherical aberration. • Young adult healthy Caucasian eyes have significantly more spherical aberration than Asian eyes when matched for age, gender, axial length and refractive error. Axial length is significantly correlated with most components of the aberration profile. 2. Intraocular light scatter: Evaluation of subjective measures and validation and application of a new objective method utilising clinically derived wavefront patterns. The main findings of this work were: • Subjective measures of clinical straylight are highly repeatable. Three measurements are suggested as the optimum number for increased reliability. • Significant differences in straylight values were found for contact lenses designed for contrast enhancement compared to clear lenses of the same design and material specifications. Specifically, grey/green tints induced significantly higher values of retinal straylight. • Wavefront patterns from a commercial Hartmann-Shack device can be used to obtain objective measures of scatter and are well correlated with subjective straylight values. • Perceived retinal stray light was similar in groups of patients implanted with monofocal and multi focal intraocular lenses. Correlation between objective and subjective measurements of scatter is poor, possibly due to different illumination conditions between the testing procedures, or a neural component which may alter with age. Careful acquisition results in highly reproducible in vivo measures of higher order aberrations; however, data from different devices are not interchangeable which brings the accuracy of measurement into question. Objective measures of intraocular straylight can be derived from clinical aberrometry and may be of great diagnostic and management importance in the future.