1,254 research outputs found
GALEX Observations of CS and OH Emission in Comet 9P/Tempel 1 During Deep Impact
GALEX observations of comet 9P/Tempel 1 using the near ultraviolet (NUV)
objective grism were made before, during and after the Deep Impact event that
occurred on 2005 July 4 at 05:52:03 UT when a 370 kg NASA spacecraft was
maneuvered into the path of the comet. The NUV channel provides usable spectral
information in a bandpass covering 2000 - 3400 A with a point source spectral
resolving power of approximately 100. The primary spectral features in this
range include solar continuum scattered from cometary dust and emissions from
OH and CS molecular bands centered near 3085 and 2575 A, respectively. In
particular, we report the only cometary CS emission detected during this event.
The observations allow the evolution of these spectral features to be tracked
over the period of the encounter. In general, the NUV emissions observed from
Tempel 1 are much fainter than those that have been observed by GALEX from
other comets. However, it is possible to derive production rates for the parent
molecules of the species detected by GALEX in Tempel 1 and to determine the
number of these molecules liberated by the impact. The derived quiescent
production rates are Q(H2O) = 6.4e27 molecules/s and Q(CS2) = 6.7e24
molecules/s, while the impact produced an additional 1.6e32 H2O molecules and
1.3e29 CS2 molecules, a similar ratio as in quiescent outgassing.Comment: 15 pages, 4 figures, accepted for publication in the Astrophysical
Journa
Microwave Devices Employing Magnetic Waves
Contains research objectives and summary of research on two research projects.Joint Services Electronics Program (Contract DAAB07-76-C-1400
Use of Di- and Tripropionate substrate analogs to probe the active site of human recombinant coproporphyrinogen oxidase
Background: Defects in the enzyme coproporphyrinogen oxidase result in accumulation of porphyrins which may affect the severity of a subset of porphyrias. Thus evaluation of this enzyme for substrate selectivity is of value. Kinetic evaluations of recombinant human coproporphyrinogen oxidase have been undertaken using six di- and tripropionate analogs of the natural substrate coproporphyrinogen-III. These Substrate analogs were modified by having alkyl groups in place of one or both of the ring 13- or 17-propionate moieties. Material/Methods: Cloned human enzyme was incubated with analogs under apparent first order conditions and with various substrate concentrations. The kinetic values, K-m and V-max, were determined. Results: Relative to the authentic substrate, the K-m values for the 13-ethyl, dimethyl and diethyl porphyrinogens were very comparable whereas the K-m values were much higher using dipropyl and dibutyl porphyrinogen and much lower for the 17-ethyl analog. For the dipropionate analogs, the V-max values were an apparent function of the carbon length of the substituent. on the C and D rings, with longer carbon length severely reducing product formation by some 4-5 orders of magnitude. Also, the two isomeric tripropionates that were tested indicated that it was more detrimental to have an ethyl group at the 13-position for both binding and catalysis. Conclusions: This work extends our understanding of porphyrin ring substituent effects reported by Cooper et al. (2005). The substituents on both the C and D rings have significant effects on both the substrate binding and catalysis by this important enzyme
Foreign Body Infection: Role of Fibronectin as a Ligand for the Adherence of Staphylococcus aureus
Foreign bodies made of polymethylmethacrylate coverslips were implanted subcutaneously into guinea pigs, were explanted four weeks later, and were tested for in vitro adherence of Staphylococcus aureus strain Wood 46. In the presence of serum, the level of staphylococcal adherence to explanted coverslips was 20 times higher than that of adherence to unimplanted coverslips. Adherence to explanted coverslips was caused by fibronectin deposits on the foreign body surface and was inhibited in a dose-related fashion by specific antibodies to fibronecti
A polarity reversal in the large-scale magnetic field of the rapidly rotating Sun HD 190771
Aims. We investigate the long-term evolution of the large-scale photospheric
magnetic field geometry of the solar-type star HD 190771. With fundamental
parameters very close to those of the Sun except for a shorter rotation period
of 8.8 d, HD 190771 provides us with a first insight into the specific impact
of the rotation rate in the dynamo generation of magnetic fields in 1
stars.
Methods. We use circularly polarized, high-resolution spectra obtained with
the NARVAL spectropolarimeter (Observatoire du Pic du Midi, France) and compute
cross-correlation line profiles with high signal-to-noise ratio to detect
polarized Zeeman signatures. From three phase-resolved data sets collected
during the summers of 2007, 2008, and 2009, we model the large-scale
photospheric magnetic field of the star by means of Zeeman-Doppler imaging and
follow its temporal evolution.
Results. The comparison of the magnetic maps shows that a polarity reversal
of the axisymmetric component of the large-scale magnetic field occurred
between 2007 and 2008, this evolution being observed in both the poloidal and
toroidal magnetic components. Between 2008 and 2009, another type of global
evolution occured, characterized by a sharp decrease of the fraction of
magnetic energy stored in the toroidal component. These changes were not
accompanied by significant evolution in the total photospheric magnetic energy.
Using our spectra to perform radial velocity measurements, we also detect a
very low-mass stellar companion to HD 190771.Comment: Accepted by Astronomy and Astrophysics (Letter to the Editor
Increased use of hypnotics in individuals with celiac disease: A nationwide case-control study
BACKGROUND: Although poor sleep is common in numerous gastrointestinal diseases, data are scarce on the risk of poor sleep in celiac disease. The objective of this study was to estimate the risk of repeated use of hypnotics among individuals with celiac disease as a proxy measure for poor sleep. METHODS: This is a nationwide case–control study including 2933 individuals with celiac disease and 14,571 matched controls from the general Swedish population. Poor sleep was defined as ≥2 prescriptions of hypnotics using prospective data from the National Prescribed Drug Register (data capture: July 2005-January 2008). We estimated odds ratios and hazard ratios for poor sleep before and after celiac disease diagnosis respectively. RESULTS: In this study, poor sleep was seen in 129/2933 individuals (4.4%) with celiac disease, as compared with 487/14,571 controls (3.3%) (odds ratio = 1.33; 95% CI = 1.08-1.62). Data restricted to sleep complaints starting ≥1 year before celiac disease diagnosis revealed largely unchanged risk estimates (odds ratio = 1.23; 95% CI = 0.88-1.71) as compared with the overall risk (odds ratio 1.33). The risk of poor sleep in celiac disease was essentially not influenced by adjustment for concomitant psychiatric comorbidity (n = 1744, adjusted odds ratio =1.26; 95% CI = 1.02-1.54) or restless legs syndrome (n = 108, adjusted odds ratio = 1.33; 95% CI = 1.08-1.63). Poor sleep was also more common after celiac disease diagnosis as compared with matched controls (hazard ratio = 1.36; 95% CI = 1.30-1.41). CONCLUSIONS: In conclusion, individuals with celiac disease suffer an increased risk of poor sleep, both before and after diagnosis. Although we cannot rule out that surveillance bias has contributed to our findings, our results are consistent with previous data suggesting that sleep complaints may be a manifestation of celiac disease. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12876-015-0236-z) contains supplementary material, which is available to authorized users
Microwave Devices Employing Magnetic Waves
Contains reports on three research projects.Joint Services Electronics Program (Contract DAAB07-76-C-1400)National Science Foundation (Grant ENG76-18359
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