2,667 research outputs found
Vibrational spectroscopic force field studies of dimethyl sulfoxide and hexakis(dimethyl sulfoxide)scandium(III) iodide, and crystal and solution structure of the hexakis(dimethyl sulfoxide)scandium(III) ion
Hexakis(dimethyl sulfoxide) scandium(III) iodide, [Sc(OS(CH3)(2))(6)]I-3 contains centrosymmetric hexasolvated scandium(III) ions with an Sc-O bond distance of 2.069(3) Angstrom. EXAFS spectra yield a mean Sc-O bond distance of 2.09(1) Angstrom for solvated scandium(III) ions in dimethyl sulfoxide solution, consistent with six-coordination. Raman and infrared absorption spectra have been recorded, also of the deuterated compound, and analysed by means of normal coordinate methods, together with spectra of dimethyl sulfoxide. The effects on the vibrational spectra of the weak intermolecular C-H...O interactions and of the dipole dipole interactions in liquid dimethyl sulfoxide have been evaluated, in particular for the S O stretching mode. The strong Raman band at 1043.6 cm(-1) and the intense IR absorption at 1062.6 cm(-1) have been assigned as the S-O stretching frequencies of the dominating species in liquid dimethyl sulfoxide, evaluated as centrosymmetric dimers with antiparallel polar S-O groups. The shifts of vibrational frequencies and force constants for coordinated dimethyl sulfoxide ligands in hexasolvated trivalent metal ion complexes are discussed. Hexasolvated scandium( III) ions are found in dimethyl sulfoxide solution and in [Sc(OSMe2)(6)]I-3. The iodide ion dipole attraction shifts the methyl group C H stretching frequency for (S-)C-H...I- more than for the intermolecular (S-)C-H...O interactions in liquid dimethyl sulfoxide
Revision of empirical electric field modeling in the inner magnetosphere using Cluster data
Using Cluster data from the Electron Drift (EDI) and the Electric Field and Wave (EFW) instruments, we revise our empirically-based, inner-magnetospheric electric field (UNH-IMEF) model at 22.662 mV/m; K-p\u3c1, 1K(p)\u3c2, 2K(p)\u3c3, 3K(p)\u3c4, 4K(p)\u3c5, and K(p)4(+). Patterns consist of one set of data and processing for smaller activities, and another for higher activities. As activity increases, the skewed potential contour related to the partial ring current appears on the nightside. With the revised analysis, we find that the skewed potential contours get clearer and potential contours get denser on the nightside and morningside. Since the fluctuating components are not negligible, standard deviations from the modeled values are included in the model. In this study, we perform validation of the derived model more extensively. We find experimentally that the skewed contours are located close to the last closed equipotential, consistent with previous theories. This gives physical context to our model and serves as one validation effort. As another validation effort, the derived results are compared with other models/measurements. From these comparisons, we conclude that our model has some clear advantages over the others
The GOAL study: a prospective examination of the impact of factor V Leiden and ABO(H) blood groups on haemorrhagic and thrombotic pregnancy outcomes
Factor V Leiden (FVL) and ABO(H) blood groups are the common influences on haemostasis and retrospective studies have linked FVL with pregnancy complications. However, only one sizeable prospective examination has taken place. As a result, neither the impact of FVL in unselected subjects, any interaction with ABO(H) in pregnancy, nor the utility of screening for FVL is defined. A prospective study of 4250 unselected pregnancies was carried out. A venous thromboembolism (VTE) rate of 1·23/1000 was observed, but no significant association between FVL and pre-eclampsia, intra-uterine growth restriction or pregnancy loss was seen. No influence of FVL and/or ABO(H) on ante-natal bleeding or intra-partum or postpartum haemorrhage was observed. However, FVL was associated with birth-weights >90th centile [odds ratio (OR) 1·81; 95% confidence interval (CI<sub>95</sub>) 1·04–3·31] and neonatal death (OR 14·79; CI<sub>95</sub> 2·71–80·74). No association with ABO(H) alone, or any interaction between ABO(H) and FVL was observed. We neither confirmed the protective effect of FVL on pregnancy-related blood loss reported in previous smaller studies, nor did we find the increased risk of some vascular complications reported in retrospective studies
5 year Global 3-mm VLBI survey of Gamma-ray active blazars
The Global mm-VLBI Array (GMVA) is a network of 14 3\,mm and 7\,mm capable
telescopes spanning Europe and the United States, with planned extensions to
Asia. The array is capable of sensitive maps with angular resolution often
exceeding 50\,as. Using the GMVA, a large sample of prominent -ray
blazars have been observed approximately 6 monthly from later 2008 until now.
Combining 3\,mm maps from the GMVA with near-in-time 7\,mm maps from the
VLBA-BU-BLAZAR program and 2\,cm maps from the MOJAVE program, we determine the
sub-pc morphology and high frequency spectral structure of -ray
blazars. The magnetic field strength can be estimated at different locations
along the jet under the assumption of equipartition between magnetic field and
relativistic particle energies. Making assumptions on the jet magnetic field
configuration (e.g. poloidal or toroidal), we can estimate the separation of
the mm-wave "core" and the jet base, and estimate the strength of the magnetic
field there. The results of this analysis show that on average, the magnetic
field strength decreases with a power-law , .
This suggests that on average, the mm-wave "core" is \,pc downstream
of the de-projected jet apex and that the magnetic field strength is of the
order \,kG, broadly consistent with the predictions of
magnetic jet launching (e.g. via magnetically arrested disks (MAD)).Comment: 6 pages, 1 figur
SiO Maser Forest at the Galactic Center
A moderately deep survey of stellar maser sources toward the Galactic center
has been made in the SiO J=1-0 v=1 and v=2 transitions (~ 43 GHz) with the
Nobeyama 45-m telescope of a beam size of about 40". At the Galactic center
(Sgr A*), 7 (4 new) SiO maser sources were detected in one beam. In order to
investigate the spatial distribution of SiO maser sources, we have also
observed the offset positions by +- 40" in Galactic longitude from the Galactic
center. In total, 7 (4 new) SiO maser sources were detected at the offset
positions. Taking into account the shorter integration time at the offset
positions, we find that the surface number density of SiO maser sources is
nearly constant at the Galactic center. The number density of SiO maser sources
is found to be an order of magnitude higher than the density of OH 1612 MHz
objects. A radial-velocity gradient in Galactic longitude was not detected.
These facts indicate that the SiO maser sources seen toward the Galactic center
are mostly associated with the stellar population of a Galactic stellar nuclear
disk of more than a few arc minute radius.Comment: 15 pages, 1 figure, Astrophysical Journal (Letters) in pres
Cold streams of ionospheric oxygen in the plasma sheet during the CDAW-6 event of March 22, 1979
During magnetospheric substorm events, the plasma and ion composition experiments in the ISEE-1 and 2 satellites detected cold ionospheric O+ streams, moving tailwards in the near Earth magnetotail. Flow is parallel to the magnetic field lines, with drift velocity in agreement with the electric field topology obtained by mapping the model ionospheric field along the magnetic field lines. Fluctuations of the flow velocity of the streams can be related to magnetotail movements. Oscillations of the flow direction and speed with periods ranging from 5 to 10 min that suggest the presence of waves are observed. The streams are observed at all distances between 15 and 6 Re from the Earth. When averaged over 360 deg, the streams show up as a low energy peak, superimposed on the distribution of isotropic plasma sheet ions. This double-peak structure of the energy spectrum seems typical of the disturbed plasma sheet
Allergic rhinoconjunctivitis doubles the risk for incident asthma – Results from a population study in Helsinki, Finland
SummaryObjectiveTo examine the incidence of allergic rhinoconjunctivitis and asthma, and to assess allergic rhinoconjunctivitis as a risk factor for incident asthma, we performed a 11-year follow-up postal survey.MethodsThe original study population was a random population sample of 8000 inhabitants of Helsinki aged 20–69 years in 1996. Participants in the first postal questionnaire survey, 6062 subjects, were invited to this follow-up study, and provided 4302 (78%) answers out of 5484 traced subjects in 2007.ResultsCumulative incidence of asthma from 1996 to 2007 was 4.0% corresponding to an annual incidence rate of 3.7/1000/year. After exclusion of those with asthma medication or physician-diagnosed chronic bronchitis or COPD at baseline in 1996, the cumulative incidence decreased to 3.5% (incidence rate 3.2/1000/year), and further to 2.7% (2.5/1000/year) when also those reporting recurrent wheeze or shortness of breath during the last year in 1996 were omitted from the population at risk. Remission of asthma occurred in 43 subjects and was 16.9% over 11 years. Cumulative 11-year incidence of allergic rhinoconjunctivitis was 16.9% corresponding to 16.8/1000/year, and cumulative remission was 18.1%. Incidence of allergic rhinoconjunctivitis was significantly lower among those who had lived in the countryside or on a farm during the first 5 years of life, but this was not true for asthma. In multivariate analysis, farm living during the first 5 years of life was protective for the development of allergic rhinoconjunctivitis, OR 0.75 (95%CI 0.57–0.99). Allergic rhinoconjunctivitis was a significant independent risk factor for incident asthma, OR 2.15 (95%CI 1.54–3.02). In the cohort, the prevalence of rhinoconjunctivitis increased from 38.0% in 1996 to 40.9% in 2007, physician-diagnosed asthma from 6.8% to 9.4%, while current smoking decreased from 31.3% to 23.3%.ConclusionIncidence of allergic rhinoconjunctivitis was higher than in earlier studies, while asthma incidence remained on similar level, both being significantly higher in women. Allergic rhinoconjunctivitis doubled the risk for incident asthma
Role of tyrosine 129 in the active site of spinach glycolate oxidase
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66136/1/j.1432-1033.1993.tb17852.x.pd
On the Calibration of Full-polarization 86GHz Global VLBI Observations
We report the development of a semi-automatic pipeline for the calibration of
86 GHz full-polarization observations performed with the Global Millimeter-VLBI
array (GMVA) and describe the calibration strategy followed in the data
reduction. Our calibration pipeline involves non-standard procedures, since
VLBI polarimetry at frequencies above 43 GHz is not yet well established. We
also present, for the first time, a full-polarization global-VLBI image at 86
GHz (source 3C 345), as an example of the final product of our calibration
pipeline, and discuss the effect of instrumental limitations on the fidelity of
the polarization images. Our calibration strategy is not exclusive for the
GMVA, and could be applied on other VLBI arrays at millimeter wavelengths. The
use of this pipeline will allow GMVA observers to get fully-calibrated datasets
shortly after the data correlation.Comment: 10 pages, 10 figures. Accepted for publication in A&
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