1,030 research outputs found
Fe XIII emission lines in active region spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph
Recent fully relativistic calculations of radiative rates and electron impact
excitation cross sections for Fe {\sc xiii} are used to generate emission-line
ratios involving 3s3p--3s3p and
3s3p--3s3p3d transitions in the 170--225 \AA and 235--450 \AA
wavelength ranges covered by the Solar Extreme-Ultraviolet Research Telescope
and Spectrograph (SERTS). A comparison of these line ratios with SERTS active
region observations from rocket flights in 1989 and 1995 reveals generally very
good agreement between theory and experiment. Several new Fe {\sc xiii}
emission features are identified, at wavelengths of 203.79, 259.94, 288.56 and
290.81 \AA. However, major discrepancies between theory and observation remain
for several Fe {\sc xiii} transitions, as previously found by Landi (2002) and
others, which cannot be explained by blending. Errors in the adopted atomic
data appear to be the most likely explanation, in particular for transitions
which have 3s3p3d D as their upper level. The most useful Fe
{\sc xiii} electron density diagnostics in the SERTS spectral regions are
assessed, in terms of the line pairs involved being (i) apparently free of
atomic physics problems and blends, (ii) close in wavelength to reduce the
effects of possible errors in the instrumental intensity calibration, and (iii)
very sensitive to changes in N over the range 10--10
cm. It is concluded that the ratios which best satisfy these conditions
are 200.03/202.04 and 203.17/202.04 for the 170--225 \AA wavelength region, and
348.18/320.80, 348.18/368.16, 359.64/348.18 and 359.83/368.16 for 235--450 \AA.Comment: 11 pages, 8 figures, 10 tables, MNRAS, in pres
The absorption of matte by sodium carbonate, and the effect on the fire-assay
It has been observed in practical and experimental work, that there is a variation in the fire assay values of some sulphide ores and mattes by the metallic iron method due to the proportions of the reagents used. This is shown in a particular manner in the use of sodium carbonate. there is also a corresponding variation in the amount of matte separating out in the assay by this method. It is a well known fact that mattes absorb both gold and silver and this has always been regarded as one objection to the assay of the ores of those metals by the latter method. The object of the experiments herein recorded is to determine those relations, and also the possibility of successful assay by the metallic iron method --page 1
Emission lines of Fe XI in the 257--407 A wavelength region observed in solar spectra from EIS/Hinode and SERTS
Theoretical emission-line ratios involving Fe XI transitions in the 257-407 A
wavelength range are derived using fully relativistic calculations of radiative
rates and electron impact excitation cross sections. These are subsequently
compared with both long wavelength channel Extreme-Ultraviolet Imaging
Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291 A), and
first-order observations (235-449 A) obtained by the Solar Extreme-ultraviolet
Research Telescope and Spectrograph (SERTS). The 266.39, 266.60 and 276.36 A
lines of Fe XI are detected in two EIS spectra, confirming earlier
identifications of these features, and 276.36 A is found to provide an electron
density diagnostic when ratioed against the 257.55 A transition. Agreement
between theory and observation is found to be generally good for the SERTS data
sets, with discrepancies normally being due to known line blends, while the
257.55 A feature is detected for the first time in SERTS spectra. The most
useful Fe XI electron density diagnostic is found to be the 308.54/352.67
intensity ratio, which varies by a factor of 8.4 between N_e = 10^8 and 10^11
cm^-3, while showing little temperature sensitivity. However, the 349.04/352.67
ratio potentially provides a superior diagnostic, as it involves lines which
are closer in wavelength, and varies by a factor of 14.7 between N_e = 10^8 and
10^11 cm^-3. Unfortunately, the 349.04 A line is relatively weak, and also
blended with the second-order Fe X 174.52 A feature, unless the first-order
instrument response is enhanced.Comment: 9 pages, 5 figures, 13 tables; MNRAS in pres
Emission lines of Fe X in active region spectra obtained with the Solar Extreme-ultraviolet Research Telescope and Spectrograph
Fully relativistic calculations of radiative rates and electron impact
excitation cross sections for Fe X are used to derive theoretical emission-line
ratios involving transitions in the 174-366 A wavelength range. A comparison of
these with solar active region observations obtained during the 1989 and 1995
flights of the Solar Extreme-ultraviolet Research Telescope and Spectrograph
(SERTS) reveals generally very good agreement between theory and experiment.
Several Fe X emission features are detected for the first time in SERTS
spectra, while the transition at 195.32 A is identified for the first time (to
our knowledge) in an astronomical source. The most useful Fe X electron density
diagnostic line ratios are assessed to be 175.27/174.53 and 175.27/177.24,
which both involve lines close in wavelength and free from blends, vary by
factors of 13 between Ne = 1E8 and 1E13 cm-3, and yet show little temperature
sensitivity. Should these lines not be available, then the 257.25/345.74 ratio
may be employed to determine Ne, although this requires an accurate evaluation
of the instrument intensity calibration over a relatively large wavelength
range. However, if the weak 324.73 A line of Fe X is reliably detected, the use
of 324.73/345.74 or 257.25/324.73 is recommended over 257.25/345.74.Comment: 11 pages, 10 figures, MNRAS in pres
Linear growth in preschool children treated with mass azithromycin distributions for trachoma: A cluster-randomized trial.
BackgroundMass azithromycin distributions have been shown to reduce mortality among pre-school children in sub-Saharan Africa. It is unclear what mediates this mortality reduction, but one possibility is that antibiotics function as growth promoters for young children.Methods and findings24 rural Ethiopian communities that had received biannual mass azithromycin distributions over the previous four years were enrolled in a parallel-group, cluster-randomized trial. Communities were randomized in a 1:1 ratio to either continuation of biannual oral azithromycin (20mg/kg for children, 1 g for adults) or to no programmatic antibiotics over the 36 months of the study period. All community members 6 months and older were eligible for the intervention. The primary outcome was ocular chlamydia; height and weight were measured as secondary outcomes on children less than 60 months of age at months 12 and 36. Study participants were not masked; anthropometrists were not informed of the treatment allocation. Anthropometric measurements were collected for 282 children aged 0-36 months at the month 12 assessment and 455 children aged 0-59 months at the month 36 assessment, including 207 children who had measurements at both time points. After adjusting for age and sex, children were slightly but not significantly taller in the biannually treated communities (84.0 cm, 95%CI 83.2-84.8, in the azithromycin-treated communities vs. 83.7 cm, 95%CI 82.9-84.5, in the untreated communities; mean difference 0.31 cm, 95%CI -0.85 to 1.47, P = 0.60). No adverse events were reported.ConclusionsPeriodic mass azithromycin distributions for trachoma did not demonstrate a strong impact on childhood growth.Trial registrationThe TANA II trial was registered on clinicaltrials.gov #NCT01202331
Fe XI emission lines in a high resolution extreme ultraviolet spectrum obtained by SERTS
New calculations of radiative rates and electron impact excitation cross
sections for Fe XI are used to derive emission line intensity ratios involving
3s^23p^4 - 3s^23p^33d transitions in the 180-223 A wavelength range. These
ratios are subsequently compared with observations of a solar active region,
obtained during the 1995 flight Solar EUV Research Telescope and Spectrograph
(SERTS). The version of SERTS flown in 1995 incorporated a multilayer grating
that enhanced the instrumental sensitivity for features in the 170 - 225 A
wavelength range, observed in second-order between 340 and 450 A. This
enhancement led to the detection of many emission lines not seen on previous
SERTS flights, which were measured with the highest spectral resolution (0.03
A) ever achieved for spatially resolved active region spectra in this
wavelength range. However, even at this high spectral resolution, several of
the Fe XI lines are found to be blended, although the sources of the blends are
identified in the majority of cases. The most useful Fe XI electron density
diagnostic line intensity ratio is I(184.80 A)/I(188.21 A). This ratio involves
lines close in wavelength and free from blends, and which varies by a factor of
11.7 between N_e = 10^9 and 10^11 cm^-3, yet shows little temperature
sensitivity. An unknown line in the SERTS spectrum at 189.00 A is found to be
due to Fe XI, the first time (to our knowledge) this feature has been
identified in the solar spectrum. Similarly, there are new identifications of
the Fe XI 192.88, 198.56 and 202.42 A features, although the latter two are
blended with S VIII/Fe XII and Fe XIII, respectively.Comment: 21 pages, 9 gigures, accepted for publication in the Astrophysical
Journa
Perioperative donor bone marrow infusion augments chimerism in heart and lung transplant recipients
Background.: We and others have demonstrated that a low level of donor cell chimerism was present for years after transplantation in tissues and peripheral blood of heart and lung recipients; it was associated, in the latter, with a lower incidence of chronic rejection. To augment this phenomenon, we initiated a trial combining simultaneous infusion of donor bone marrow with heart or lung allotransplantation. Methods.: Between September 1993 and January 1995, 15 nonconditioned patients received either heart (n = 10) or lung (n = 5) allografts concurrently with an infusion of unmodified donor bone marrow (3.0 × 108 cells/kg), and were maintained on an immunosuppressive regimen consisting of tacrolimus and steroids. Results.: There was no complication associated with the infusion of donor bone marrow. Chimerism was detectable in 73% of bone marrow-augmented patients up to the last sample tested. Of the 5 control recipients who did not receive bone marrow infusion, only 1 had detectable chimerism by flow on postoperative day 15, which dwindled to an undetectable level by postoperative day 36. None of the patients had evidence of donor-specific immune modulation by mixed lymphocyte reaction. Conclusions.: The combined infusion of donor bone marrow and heart or lung transplantation, without preconditioning of the recipient, is safe and is associated with an augmentation of donor cell chimerism. © 1995 The Society of Thoracic Surgeons
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