The abundance of HCN in circumstellar envelopes of AGB stars of different chemical types

A multi-transition survey of HCN (sub-) millimeter line emission from a large sample of AGB stars of different chemical type is presented. The data are analysed and circumstellar HCN abundances are estimated. The sample stars span a large range of properties such as mass-loss rate and photospheric C/O-ratio. The analysis of the new data allows for more accurate estimates of the circumstellar HCN abundances and puts new constraints on chemical models. In order to constrain the circumstellar HCN abundance distribution a detailed non-LTE excitation analysis, based on the Monte Carlo method, is performed. Effects of line overlaps and radiative excitation from dust grains are included. The median values for the derived abundances of HCN (with respect to H2) are 3x10-5, 7x10-7 and 10-7 for carbon stars (25 stars), S-type AGB stars (19 stars) and M-type AGB stars (25 stars), respectively. The estimated sizes of the HCN envelopes are similar to those obtained in the case of SiO for the same sample of sources and agree well with previous results from interferometric observations, when these are available. We find that there is a clear dependence of the derived circumstellar HCN abundance on the C/O-ratio of the star, in that carbon stars have about two orders of magnitude higher abundances than M-type AGB stars, on average. The derived HCN abundances of the S-type AGB stars have a larger spread and typically fall in between those of the two other types, however, slightly closer to the values for the M-type AGB stars. For the M-type stars, the estimated abundances are much higher than what would be expected if HCN is formed in thermal equilibrium. However, the results are also in contrast to predictions from recent non-LTE chemical models, where very little difference is expected in the HCN abundances between the various types of AGB stars.Comment: Accepted for publication in A&

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

The Dynamics, Prevalence and Impact of Nematode Infections in Organically Raised Sheep in Sweden

A three-year survey (1997–99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei, T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs

Electrostatic Turbulence and Debye-scale Structures in Collisionless Shocks

We present analysis of more than 100 large-amplitude bipolar electrostatic structures in a quasi-perpendicular supercritical Earth's bow shock crossing, measured by the Magnetospheric Multiscale spacecraft. The occurrence of the bipolar structures is shown to be tightly correlated with magnetic field gradients in the shock transition region. The bipolar structures have negative electrostatic potentials and spatial scales of a few Debye lengths. The bipolar structures propagate highly oblique to the shock normal with velocities (in the plasma rest frame) of the order of the ion-acoustic velocity. We argue that the bipolar structures are ion phase space holes produced by the two-stream instability between incoming and reflected ions. This is the first identification of the ion two-stream instability in collisionless shocks

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

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

Disease activity in and quality of life of patients with psoriatic arthritis mutilans : the Nordic PAM Study

Objective: To describe the social status and health-related quality of life of patients with psoriatic arthritis mutilans (PAM) in the Nordic countries.Method: Patients with at least one mutilated joint confirmed by radiology were studied. Disease activity involving joints and skin, physician-assessed disease activity, and patient's education and work status were recorded. Data from the 36-item Short Form Health Survey, Health Assessment Questionnaire and Dermatology Life Quality Index questionnaire were gathered and correlated with disease duration, pain, and general well-being (visual analogue scale). The controls were 58 Swedish patients with long-standing psoriatic arthritis sine PAM.Results: Sixty-seven patients were included. Patients with PAM had a protracted disease history (3314years) and disease onset at a relatively early age (30 +/- 12years). Overall inflammatory activity at inclusion was mild to moderate. The mean number of mutilated joints was 8.2 and gross deformity was found in 16% of patients. Forty per cent were treated with biological and 32% with conventional synthetic disease-modifying anti-rheumatic drugs. Forty-two per cent had retired early or were on sick leave. Impaired functional capacity with little or no ability to perform self-care or everyday tasks was reported by 21% of the patients. Patients between 45 and 60years of age reported the most impaired quality of life in comparison to the control group.Conclusion: PAM seriously affects social functioning. Whether early recognition of PAM and new forms of therapy can improve disease outcome and quality of life remains to be studied.Peer reviewe

EMIC Waves in the Outer Magnetosphere: Observations of an Off-Equator Source Region.

Electromagnetic ion cyclotron (EMIC) waves at large L shells were observed away from the magnetic equator by the Magnetospheric MultiScale (MMS) mission nearly continuously for over four hours on 28 October 2015. During this event, the wave Poynting vector direction systematically changed from parallel to the magnetic field (toward the equator), to bidirectional, to antiparallel (away from the equator). These changes coincide with the shift in the location of the minimum in the magnetic field in the southern hemisphere from poleward to equatorward of MMS. The local plasma conditions measured with the EMIC waves also suggest that the outer magnetospheric region sampled during this event was generally unstable to EMIC wave growth. Together, these observations indicate that the bidirectionally propagating wave packets were not a result of reflection at high latitudes but that MMS passed through an off-equator EMIC wave source region associated with the local minimum in the magnetic field

G359.87+0.18: An FR II Radio Galaxy 15 Arcminutes from Sgr A*. Implications for the Scattering Region in the Galactic Center

G359.87+0.18 is an enigmatic object located 15' from Sgr A*. It has been variously classified as an extragalactic source, Galactic jet source, and young supernova remnant. We present new observations of G359.87+0.18 between 0.33 and 15 GHz and use these to argue that this source is an Faranoff-Riley II radio galaxy. We are able to place a crude limit on its redshift of z > 0.1. The source has a spectral index \alpha < -1 (S \propto \nu^\alpha), suggestive of a radio galaxy with a redshift z >~ 2. The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. If the region covers the Galactic center uniformly, the implied diameter for a background source is at least 600" at 0.33 GHz, in contrast with the observed 20" diameter of G359.87+0.18. Using the scattering diameter of a nearby OH maser OH 359.762+0.120 and the widths of two, nearby, non-thermal threads, G0.08+0.15 and G359.79+0.17, we show that a uniform scattering region should cover G359.87+0.18. We therefore conclude that the Galactic center scattering region is inhomogeneous on a scale of 5' (~ 10 pc at a distance of 8.5 kpc). This scale is comparable to the size scale of molecular clouds in the Galactic center. The close agreement between these two lengths scales is an indication that the scattering region is linked intimately to the Galactic center molecular clouds.Comment: Accepted for publication in the ApJ, vol. 515, LaTeX2e manuscript using aaspp4 macro, 19 pages, 8 figures in 11 PostScript file