1,083 research outputs found
An infrared study of galactic OH/IR stars. II. The `GLMP sample' of red oxygen-rich AGB stars
We present optical and near-infrared finding charts taken from the DSS and
2MASS surveys of 94 IRAS sources selected from the GLMP catalogue
(Garc\'{\i}a-Lario 1992), and accurate astrometry (~0.2") for most of them.
Selection criteria were very red IRAS colours representative for OH/IR stars
with optically thick circumstellar shells and the presence of variability
according to the IRAS variability index (VAR>50). The main photometric
properties of the stars in this `GLMP sample' are presented, discussed and
compared with the correspondent properties of the `Arecibo sample' of OH/IR
stars studied in Jim\'enez-Esteban et al. (2005a). We find that 37% of the
sample (N=34) have no counterpart in the 2MASS, implying extremely high optical
depths of their shells. Most of the sources identified in the 2MASS are faint
(K>~8) and of very red colour in the near-infrared, as expected. The brightest
2MASS counterpart (K=5.3mag) was found for IRAS 18299--1705. Its blue colour
H--K=1.3 suggests that IRAS 8299--1705 is a post-AGB star. A couple of GLMP
sources have faint but relatively blue counterparts. They might be misidentifed
field stars or stars hich experienced recently a drop of their mass loss rates.
The `GLMP sample' in general is made of oxygen-rich AGB stars, which are highly
obscured by their circumstellar shells. They belong to the same population as
the reddest OH/IR stars in the `Arecibo sample'.Comment: 15 pages, 9 figures, for associated finding charts see:
http://www.hs.uni-hamburg.de/DE/Ins/Per/Jimenez-Esteban/Thesis/Atlas/glmp_ind
ex.html accepted for publicating by A&A on 21/07/200
Super-resolution far-field ghost imaging via compressive sampling
Much more image details can be resolved by improving the system's imaging
resolution and enhancing the resolution beyond the system's Rayleigh
diffraction limit is generally called super-resolution. By combining the sparse
prior property of images with the ghost imaging method, we demonstrated
experimentally that super-resolution imaging can be nonlocally achieved in the
far field even without looking at the object. Physical explanation of
super-resolution ghost imaging via compressive sampling and its potential
applications are also discussed.Comment: 4pages,4figure
Predictors of PTSD and CPTSD in UK firefighters
Background: Globally, professional firefighters are often exposed to traumatic events and are at high risk of developing posttraumatic stress disorder (PTSD) symptoms. Objective: With the publication of the 11th edition of the International Classification of Diseases (ICD-11) there arose a need for research based on the new diagnostic criteria, and the associated disorder, Complex PTSD (CPTSD). Method: Participants were 1300 former or present firefighters from the UK. Prevalence rates of PTSD and CPTSD were estimated using International Trauma Questionnaire in accordance with ICD-11 criteria, and service related and personal trauma exposure were also assessed using an anonymous online questionnaire. Multinomial logistic regression was performed to assess how service and personal trauma exposure predicted PTSD and CPTSD. Results: CPTSD criteria were met by 18.23% (95% CI 16.13–20.33%) and PTSD criteria were met by 5.62% (95% CI 4.37–6.87%) of the sample. Experiencing higher levels of service-related trauma significantly increased the risk for both PTSD and CPTSD, and nonwork related trauma uniquely predicted CPTSD but not PTSD. Conclusions: This study provided the first examination of the new ICD-11 criteria for PTSD and CPTSD in a large sample of firefighters, and CPTSD was more common than PTSD. Exposure to multiple different types of trauma increased the odds of PTSD and CPTSD
Dust and the spectral energy distribution of the OH/IR star OH 127.8+0.0: Evidence for circumstellar metallic iron
We present a fit to the spectral energy distribution of OH 127.8+0.0, a
typical asymptotic giant branch star with an optically thick circumstellar dust
shell. The fit to the dust spectrum is achieved using non-spherical grains
consisting of metallic iron, amorphous and crystalline silicates and water ice.
Previous similar attempts have not resulted in a satisfactory fit to the
observed spectral energy distributions, mainly because of an apparent lack of
opacity in the 3--8 micron region of the spectrum. Non-spherical metallic iron
grains provide an identification for the missing source of opacity in the
near-infrared. Using the derived dust composition, we have calculated spectra
for a range of mass-loss rates in order to perform a consistency check by
comparison with other evolved stars. The L-[12 micron] colours of these models
correctly predict the mass-loss rate of a sample of AGB stars, strengthening
our conclusion that the metallic iron grains dominate the near-infrared flux.
We discuss a formation mechanism for non-spherical metallic iron grains.Comment: 10 pages, 6 figures, accepted for publication by A&
Divergent roles for antigenic drive in the aetiology of primary versus dasatinib-associated CD8(+) TCR-Vβ(+) expansions
CD8(+) T-cell expansions are the primary manifestation of T-cell large granular lymphocytic leukemia (T-LGLL), which is frequently accompanied by neutropenia and rheumatoid arthritis, and also occur as a secondary phenomenon in leukemia patients treated with dasatinib, notably in association with various drug-induced side-effects. However, the mechanisms that underlie the genesis and maintenance of expanded CD8(+) T-cell receptor (TCR)-V beta(+) populations in these patient groups have yet to be fully defined. In this study, we performed a comprehensive phenotypic and clonotypic assessment of expanded (TCR-V beta(+)) and residual (TCR-V beta(-)) CD8(+) T-cell populations in T-LGLL and dasatinib-treated chronic myelogenous leukemia (CML) patients. The dominant CD8(+) TCR-V beta(+) expansions in T-LGLL patients were largely monoclonal and highly differentiated, whereas the dominant CD8(+) TCR-V beta(+) expansions in dasatinib-treated CML patients were oligoclonal or polyclonal, and displayed a broad range of memory phenotypes. These contrasting features suggest divergent roles for antigenic drive in the immunopathogenesis of primary versus dasatinib-associated CD8(+) TCR-V beta(+) expansions.Peer reviewe
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Literacy outcomes for Deaf and Hard of Hearing primary school children: A cohort comparison study
Purpose: This study compared the language and literacy of two cohorts of children with severe-profound hearing loss, recruited 10 years apart, to determine whether outcomes had improved in line with the introduction of newborn hearing screening and access to improved hearing aid technology.
Method: Forty-two deaf children, aged 5 -7 years with a mean unaided loss of 102 DB, were assessed on language, reading and phonological skills. Their performance was compared to that of a similar group of 32 deaf children assessed 10 years earlier, and also a group of 40 hearing children of similar single word reading ability.
Results: English vocabulary was significantly higher in the new cohort, although it was still below chronological age. Phonological awareness and reading ability had not significantly changed over time. In both cohorts English vocabulary predicted reading but phonological awareness was only a significant predictor for the new cohort.
Conclusions: The current results show that vocabulary knowledge of children with severe-profound hearing loss has improved over time but there has not been a commensurate improvement in phonological skills or reading. They suggest that children with severe-profound hearing loss will require continued support to develop robust phonological coding skills to underpin reading
Microcin H47 System: An Escherichia coli Small Genomic Island with Novel Features
Genomic islands are DNA regions containing variable genetic information related to secondary metabolism. Frequently, they have the ability to excise from and integrate into replicons through site-specific recombination. Thus, they are usually flanked by short direct repeats that act as attachment sites, and contain genes for an integrase and an excisionase which carry out the genetic exchange. These mobility events would be at the basis of the horizontal transfer of genomic islands among bacteria
The governance of co-operatives and mutual associations: a paradox perspective
This paper presents a new theoretical framework for understanding the governance of co-operative and mutual organisations. The theoretical literature on the governance of co-operatives is relatively undeveloped in comparison with that on corporate governance. The paper briefly reviews some of the main theoretical perspectives on corporate governance and discusses how they can be usefully extended to throw light on the governance of co-operatives and mutuals. However, taken individually these different theories are rather one dimensional, only illuminating a particular aspect of the board's role. This has lead to calls for a new conceptual framework that can help integrate the insights of these different theories. The paper argues that a paradox perspective offers a promising way forward. Contrasting the different theoretical perspectives highlights some of the important paradoxes, ambiguities and tensions that boards face
Glucocorticoids Inhibit CRH/AVP-Evoked Bursting Activity of Male Murine Anterior Pituitary Corticotrophs
This is the final version of the article. Available from the publisher via the DOI in this record.Corticotroph cells from the anterior pituitary are an integral component of the hypothalamic-pituitary-adrenal (HPA) axis, which governs the neuroendocrine response to stress. Corticotrophs are electrically excitable and fire spontaneous single-spike action potentials and also display secretagogue-induced bursting behavior. The HPA axis function is dependent on effective negative feedback in which elevated plasma glucocorticoids result in inhibition at the level of both the pituitary and the hypothalamus. In this study, we have used an electrophysiological approach coupled with mathematical modeling to investigate the regulation of spontaneous and CRH/arginine vasopressin-induced activity of corticotrophs by glucocorticoids. We reveal that pretreatment of corticotrophs with 100 nM corticosterone (CORT; 90 and 150 min) reduces spontaneous activity and prevents a transition from spiking to bursting after CRH/arginine vasopressin stimulation. In addition, previous studies have identified a role for large-conductance calcium- and voltage-activated potassium (BK) channels in the generation of secretagogue-induced bursting in corticotrophs. Using the dynamic clamp technique, we demonstrated that CRH-induced bursting can be switched to spiking by subtracting a fast BK current, whereas the addition of a fast BK current can induce bursting in CORT-treated cells. In addition, recordings from BK knockout mice (BK(-/-)) revealed that CORT can also inhibit excitability through BK-independent mechanisms to control spike frequency. Thus, we have established that glucocorticoids can modulate multiple properties of corticotroph electrical excitability through both BK-dependent and BK-independent mechanisms.This work was supported by Grant 082407 from the Wellcome
Trust (to M.J.S. and P.R.), Grant J008893 from the Medical
Research Council (to M.J.S.), and Grant DK43200 from the
National Institutes of Health (to R.B.). P.J.D. was supported by
a Medical Reseach Council PhD studentship in the College of
Medicine and Veterinary Medicine, University of Edinburgh
Nitrate and Sediment Fluxes from a California Rangeland Watershed
Long-term water quality records for assessing natural variability, impact of management, and that guide regulatory processes to safeguard water resources are rare for California oak woodland rangelands. This study presents a 20-yr record (1981-2000) of nitrate-nitrogen (NO3-N) and suspended sediment export from a typical, grazed oak woodland watershed (103 ha) in the northern Sierra Nevada foothills of California. Mean annual precipitation over the 20-yr period was 734 mm yr(-1) (range 366-1205 mm yr(-1)). Mean annual stream flow was 353 mm y(-1) (range 87-848 mm yr(-1)). Average annual stream flow was 48.1 +/- 16% of precipitation. Mean annual NO3-N export was 1.6 kg ha(-1) yr(-1) (range 0.18-3.6 kg ha(-1) yr(-1)). Annual NO3-N export significantly (P < 0.05) increased with increasing annual stream flow and precipitation. Mean daily NO3-N export was 0.004 kg ha(-1) d(-1) (range 10(-5) to 0.55 kg ha(-1) d(-1)). Mean annual suspended sediment export was 198 kg ha(-1) yr(-1) (range 23-479 kg ha(-1) yr(-1)). There was a positive relationship (P < 0.05) between annual suspended sediment export, annual stream How and precipitation. Mean daily suspended sediment export was 0.54 kg ha(-1) d(-1) (range 10(-4) to 155 kg ha(-1) d(-1)). Virtually no sediment was exported during the dry season. The large variation in daily and annual fluxes highlights the necessity of using long-term records to establish quantitative water quality targets for rangelands and demonstrates the difficulty of designing a water quality monitoring program for these ecosystems
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