Spectra of two bright ( −11 mag) Perseid meteors are studied. Monochromatic light curves are constructed and the spectra are analyzed at selected points along the trajectory. The shift of maxima of ...low excitation iron lines down the trajectory in meteor flares is observed and explained by a longer radiative lifetime of the upper levels for these lines. Two spectral components with the temperatures of 4400–4800 K and 10,000 K, respectively, are identified in the spectra in accordance with previous findings. The ratio of both components, in terms of mass, varied smoothly from about 100:1 over 15:1 to 30:1. This ratio is not an unambiguous function of meteor velocity, height and brightness but depends on the previous evolution of ablation. The abundances of heavy elements are found consistent with the chemical composition of carbonaceous chondrites and the dust of comet Halley. Hydrogen, however, is not more abundant than in carbonaceous chondrites and thus significantly less than in cometary dust. The initial masses of the two meteoroids are estimated at 40 and 80 g, respectively. The meteor V-band luminous efficiency is found to vary in the range log
τ
v = −11.8 to −12.0 in magnitude c.g.s. units. For the panchromatic luminous efficiency use of the value of −11.4 for bright Perseids is recommended. Nearly 1.5% of meteoroid kinetic energy is radiated out in the Ca II lines and 1 % in all other lines between 3500 and 6600 Å.
— Relative chemical abundances of 13 meteoroids were determined by averaging the composition of the radiating gas along the fireball path that originated during their penetration into the Earth's ...atmosphere. Mg, Fe, Ni, Cr, Mn, and Co abundances, relative to Si, are similar to those reported for CI and CM carbonaceous chondrites and interplanetary dust particles. In contrast, relative abundances of Ca and Ti in meteor spectra indicate that these elements suffer incomplete evaporation processes. The chemical composition of all meteoroids studied in this work differs from that of 1P/Halley dust.
— The properties and history of the parent meteoroid of the Morávka H5–6 ordinary chondrites have been studied by a combination of various methods. The pre‐atmospheric mass of the meteoroid was ...computed from fireball radiation, infrasound, seismic signal, and the content of noble gases in the meteorites. All methods gave consistent results. The best estimate of the pre‐atmospheric mass is 1500 ± 500 kg. The fireball integral bolometric luminous efficiency was 9%, and the acoustic efficiency was 0.14%. The meteoroid cosmic ray exposure age was determined to be (6.7 ± 1.0) × 106 yr. The meteorite shows a clear deficit of helium, both 3He and 4He. This deficit can be explained by solar heating. Numerical backward integration of the meteoroid orbit (determined in a previous paper from video records of the fireball) shows that the perihelion distance was probably lower than 0.5 AU and possibly as low as 0.1 AU 5 Ma ago. The collision which excavated Morávka probably occurred while the parent body was on a near‐Earth orbit, as opposed to being confined entirely to the main asteroid belt. An overview of meteorite macroscopic properties, petrology, mineralogy, and chemical composition is given. The meteorites show all mineralogical features of H chondrites. The shock level is S2. Minor deviations from other H chondrites in abundances of trace elements La, Ce, Cs, and Rb were found. The ablation crust is enriched with siderophile elements.
BACKGROUND AND AIMS To investigate the importance of lipase on gastric functions, we studied the effects of orlistat, a potent and specific inhibitor of lipase, on postprandial gastric acidity and ...gastric emptying of fat. METHODS Fourteen healthy volunteers participated in a double blind, placebo controlled, randomised study. In a two way cross over study with two test periods of five days, separated by at least 14 days, orlistat 120 mg three times daily or placebo was given with standardised daily meals. In previous experiments we found that this dose almost completely inhibited postprandial duodenal lipase activity. Subjects underwent 28 hour intragastric pH-metry on day 4, and a gastric emptying study with a mixed meal (800 kcal) labelled with 999mTc sulphur colloid (solids) and 111Inthiocyanate (fat) on day 5. Gastric pH data were analysed for three postprandial hours and the interdigestive periods. RESULTS Orlistat inhibited almost completely (by 75%) lipase activity and accelerated gastric emptying of both the solid (by 52%) and fat (by 44%) phases of the mixed meal (p<0.03). Orlistat increased postprandial gastric acidity (from a median pH of 3.3 to 2.7; p<0.01). Postprandial cholecystokinin release was lower with orlistat (p<0.03). CONCLUSION Lipase has an important role in the regulation of postprandial gastric acid secretion and fat emptying in humans. These effects might be explained by lipolysis induced release of cholecystokinin.
In the absence of a firm link between individual meteorites and their asteroidal parent bodies, asteroids are typically characterized only by their light reflection properties, and grouped ...accordingly into classes. On 6 October 2008, a small asteroid was discovered with a flat reflectance spectrum in the 554-995nm wavelength range, and designated 2008 TC3 (refs 4-6). It subsequently hit the Earth. Because it exploded at 37km altitude, no macroscopic fragments were expected to survive. Here we report that a dedicated search along the approach trajectory recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95kg. Analysis of one of these meteorites shows it to be an achondrite, a polymict ureilite, anomalous in its class: ultra-fine-grained and porous, with large carbonaceous grains. The combined asteroid and meteorite reflectance spectra identify the asteroid as F class, now firmly linked to dark carbon-rich anomalous ureilites, a material so fragile it was not previously represented in meteorite collections.
We analyzed serendipitous observations by the Meteosat 8 weather satellite of the fireball caused by the entry of the small asteroid (or large meteoroid) 2008 TC sub(3) over northern Sudan on October ...7, 2008. Meteosat 8 scans the Earth in 5 min cycles. The fireball was captured in the 2:45 UT images in four visible-near infrared channels (0.6-1.6 m) at a height of 45 km, and in eight mid infrared channels (3.9-13.4 m) at a height of 33 km. The latter channels also detected at least two dust clouds deposited in the atmosphere at the heights of about 44 and 36 km. The dust deposition was a result of severe atmospheric fragmentation of the asteroid, accompanied by fireball flares, which could be detected in the light scattered by the Earth's surface. The fireball brightness was measured at two random heights, 45 and 37.5 km, where it reached -18.8 and -19.7 mag, respectively. The peak brightness was probably higher than -20 mag. The color temperature of the fireball at 45 km was K. Infrared spectra of the fresh dust clouds were dominated by the 10 m Si-O band caused by recondensed amorphous silicates. Five minutes later, the dust clouds were detected in absorption of thermal radiation of the Earth. At that time, the silicates were largely crystalline, suggesting silicate smoke temperatures exceeding 1000 K. The total mass of the silicate smoke was estimated to be kg. More mass was probably contained in larger, micron sized, and colder dust particles resulting from incomplete sublimation of the asteroidal material and detected later by Meteosat 8 and 9 in scattered sunlight. Based on the heights of asteroid fragmentations, we guess that the bulk porosity of 2008 TC sub(3) was of the order of 50%, i.e. higher than the porosity of the recovered meteorite Almahata Sitta.
Treatment of chronic HCV infection has become a priority in HIV+ patients, given the faster progression to end-stage liver disease. The primary endpoint of this study was to evaluate and compare ...antiviral efficacy of Peginterferon alpha 2a plus ribavirin in HIV-HCV co-infected and HCV mono-infected patients, and to examine whether 6 months of therapy would have the same efficacy in HIV patients with favourable genotypes 2 and 3 as in mono-infected patients, to minimise HCV-therapy-related toxicities. Secondary endpoints were to evaluate predictors of sustained virological response (SVR) and frequency of side-effects.
Patients with genotypes 1 and 4 were treated for 48 weeks with Pegasys 180 microg/week plus Copegus 1000-1200 mg/day according to body weight; patients with genotypes 2 and 3 for 24 weeks with Pegasys 180 microg/week plus Copegus 800 mg/day.
132 patients were enrolled in the study: 85 HCV mono-infected (38: genotypes 1 and 4; 47: genotypes 2 and 3), 47 HIV-HCV co-infected patients (23: genotypes 1 and 4; 24: genotypes 2 and 3). In an intention-to-treat analysis, SVR for genotypes 1 and 4 was observed in 58% of HCV mono-infected and in 13% of HIV-HCV co-infected patients (P = 0.001). For genotypes 2 and 3, SVR was observed in 70% of HCV mono-infected and in 67% of HIV-HCV co-infected patients (P = 0.973). Undetectable HCV-RNA at week 4 had a positive predictive value for SVR for mono-infected patients with genotypes 1 and 4 of 0.78 (95% CI: 0.54-0.93) and of 0.81 (95% CI: 0.64-0.92) for genotypes 2 and 3. For co-infected patients with genotypes 2 and 3, the positive predictive value of SVR of undetectable HCV-RNA at week 4 was 0.76 (95%CI, 0.50-0.93). Study not completed by 22 patients (36%): genotypes 1 and 4 and by 12 patients (17%): genotypes 2 and 3.
Genotypes 2 or 3 predict the likelihood of SVR in HCV mono-infected and in HIV-HCV co-infected patients. A 6-month treatment with Peginterferon alpha 2a plus ribavirin has the same efficacy in HIV-HCV co-infected patients with genotypes 2 and 3 as in mono-infected patients. HCV-RNA negativity at 4 weeks has a positive predictive value for SVR. Aggressive treatment of adverse effects to avoid dose reduction, consent withdrawal or drop-out is crucial to increase the rate of SVR, especially when duration of treatment is 48 weeks. Sixty-one percent of HIV-HCV co-infected patients with genotypes 1 and 4 did not complete the study against 4% with genotypes 2 and 3.
A detailed analysis of a photographic spectrum of a Geminid fireball obtained in December 14, 1961 at the Ondrejov Observatory is presented. We have computed a synthetic spectrum for the fireball and ...compared it with the observed spectrum assuming chemical equilibrium in the meteor head. In this way we have determined relative chemical abundances in meteor vapors. Comparing the relative chemical abundances of this Geminid meteoroid with those obtained from meteoroids associated with comets 55P/Tempel-Tuttle and 109P/Swift-Tuttle we found no significant chemical differences in main rock-forming elements. Despite of this similarity, the deepest penetration of the Geminid meteoroids and their ability to reach high rotation rates in space without fragmentation suggest that thermal processing is affecting their physical properties. We suggest that as consequence of space weathering a high-strength envelope is produced around these particles. In this picture, heating processes of the mineral phases could result in the peculiar properties observed during atmospheric entry of the Geminid meteoroids, especially their strength, which is evidenced by its resistance to ablation. Finally, although one meteoroid cannot be obviously considered as representative of the composition of its parent body, we conclude that 3200 Phaethon is able to produce millimetre-size debris nearly chondritic in composition, but the measured slight overabundance of Na would support a cometary origin for this body.
To evaluate a magnetic resonance (MR) imaging method for simultaneous assessment of gastric emptying and motility.
Gastric emptying and motility were measured in nine volunteers after ingestion of a ...liquid meal. A specially designed MR imaging protocol was used that allowed simultaneous assessment of gastric emptying (spatial resolution, 1.5 mm; corrected for gastric secretion volume) and gastric motility (temporal resolution, 1.2 seconds; spatial resolution, 3.1 mm). To evaluate the ability to detect small changes in gastric motor activity with findings from this method, the influence of a prokinetic agent (loxiglumide) on gastric emptying and motility was tested in five volunteers.
Each contraction could be individually visualized at MR imaging. Administration of loxiglumide resulted in decreased gastric half-emptying time (mean +/- 1 standard error of the mean, 88.1 minutes +/- 6.3 for the placebo and 39.1 minutes +/- 6.7 for loxiglumide) and increased gastric motility (contraction frequency, 2.26 contractions per minute +/- 0.15 for the placebo and 3.04 per minute +/- 0.04 for loxiglumide).
MR imaging makes it feasible to study gastric emptying and gastric motility and to determine the influence of drugs on gastric motor activity.
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