80 research outputs found
On the binarity of Herbig Ae/Be stars
We present high resolution spectro-astrometry of a sample of 28 Herbig Ae/Be
and 3 F-type pre-main sequence stars. The spectro-astrometry is shown from both
empirical and simulated data to be capable of detecting binary companions that
are fainter by up to 6 magnitudes at separations larger than 0.1 arcsec. The
nine targets that were previously known to be a binary are all detected. In
addition, we report the discovery of 6 new binaries and present 5 further
possible binaries. The resulting binary fraction of 68+/-11 per cent is the
largest reported for any observed sample of Herbig Ae/Be stars, presumably
because of the exquisite sensitivity of spectro-astrometry for detecting binary
systems. The data hint that the binary frequency of the Herbig Be stars is
larger than for the Herbig Ae stars. The appendix presents model simulations to
assess the capabilities of spectro-astrometry and reinforces the empirical
findings. Two objects, HD 87643 and Z CMa, display evidence for asymmetric
outflows. Finally, the position angles of the binary systems have been compared
with available orientations of the circumprimary disc and these appear to be
co-planar. The alignment between the circumprimary discs and the binary systems
strongly suggests that the formation of binaries with intermediate mass
primaries is due to fragmentation as the alternative, stellar capture, does not
naturally predict aligned discs. The aligment extends to the most massive
B-type stars in our sample. This leads us to conclude that formation mechanisms
that do result in massive stars, but predict random angles beween the binaries
and the circumprimary disks, such as stellar collisions, are also ruled out for
the same reason.Comment: MNRAS accepted, 18 page
Vasopressin Regulates the Phosphorylation State of AMP-activated Protein Kinase (AMPK) in MDCK-C7 Cells
AMP-activated protein kinase (AMPK) is a regulatory kinase coupling cellular metabolism with ion transport. Madin-Darby Canine Kidney-Clone 7 (MDCK-C7) cells possess characteristics of the renal principal cell type, express the cystic fibrosis transmembrane regulator and the epithelial Na(+) channel, and display NPPB and amiloride-sensitive transepithelial transport when stimulated with [Arg(8)]-vasopressin. [Arg(8)]-vasopressin binding to its receptor on the basolateral membrane of MDCK-C7 results in cAMP production, activation of cAMP-dependent protein kinase A (PKA), and increases in Cl(-) and Na(+) transport. Ussing-style electrophysiology showed that the PKA inhibitor, H89, blocked Cl(-) and Na(+) transport. Unexpectedly, [Arg(8)]-vasopressin stimulation resulted in the dephosphorylation of pAMPK(thr172). H89 did not prevent this, suggesting that the dephosphorylation is independent of PKA. 24 hour, but not 15 minute, incubation with the AMPK activator, AICAR, also blocked [Arg(8)]-vasopressin-stimulated currents. Contrary to previous studies, immunoblotting revealed that AICAR did not increase abundance of the active, phosphorylated form of AMPK (pAMPK(thr172)); although, AICAR treatment significantly blocked [Arg(8)]-vasopressin -stimulated cAMP production. [Arg(8)]-vasopressin still caused pAMPK(thr172) dephosphorylation in the presence of AICAR, suggesting that this effect is also independent of cAMP. In summary, these data suggest [Arg(8)]-vasopressin regulates AMPK phosphorylation and that AICAR inhibits ion transport independently of AMPK in MDCK-C7 cells
IVOA Recommendation: IVOA Photometry Data Model
The Photometry Data Model (PhotDM) standard describes photometry filters,
photometric systems, magnitude systems, zero points and its interrelation with
the other IVOA data models through a simple data model. Particular attention is
given necessarily to optical photometry where specifications of magnitude
systems and photometric zero points are required to convert photometric
measurements into physical flux density units
ESASky v.2.0: all the skies in your browser
With the goal of simplifying the access to science data to scientists and
citizens, ESA recently released ESASky (http://sky.esa.int), a new open-science
easy-to-use portal with the science-ready Astronomy data from ESA and other
major data providers. In this presentation, we announced version 2.0 of the
application, which includes access to all science-ready images, catalogues and
spectra, a feature to help planning of future JWST observations, the
possibility to search for data of all (targeted and serendipitously observed)
Solar System Objects in Astronomy images, a first support to mobile devices and
several other smaller usability features. We also discussed the future
evolution of the portal and the lessons learnt from the 1+ year of operations
from the point of view of access, visualization and manipulation of big
datasets (all sky maps, also called HiPS) and large catalogues (like e.g. the
Gaia DR1 catalogues or the Hubble Source Catalogue) and the design and
validation principles for the development of friendly GUIs for thin layer web
clients aimed at scientists.Comment: 4 pages, 2 figures, ADASS 2017 conference proceeding
Determinants of Stunting and Severe Stunting Among Under-Fives in Tanzania: Evidence from the 2010 Cross-Sectional Household Survey.
Stunting is one of the main public health problems in Tanzania. It is caused mainly by malnutrition among children aged less than 5 years. Identifying the determinants of stunting and severe stunting among such children would help public health planners to reshape and redesign new interventions to reduce this health hazard. This study aimed to identify factors associated with stunting and severe stunting among children aged less than five years in Tanzania. The sample is made up of 7324 children aged 0-59 months, from the Tanzania Demographic and Health Surveys 2010. Analysis in this study was restricted to children who lived with the respondent (women aged 15-49 years). Stunting and severe stunting were examined against a set of individual-, household- and community-level factors using simple and multiple logistic regression analyses. The prevalence of stunting and severe stunting were 35.5 % [95 % Confidence interval (CI): 33.3-37.7] and 14.4 % (95 % CI: 12.9-16.1) for children aged 0-23 months and 41.6 % (95 % CI: 39.8-43.3) and 16.1 % (95 % CI: 14.8-17.5) for children aged 0-59 months, respectively. Multivariable analyses showed that the most consistent significant risk factors for stunted and severely-stunted children aged 0-23 and 0-59 months were: mothers with no schooling, male children, babies perceived to be of small or average size at birth by their mothers and unsafe sources of drinking water [adjusted odds ratio (AOR) for stunted children aged 0-23 months = 1.37; 95 % CI: (1.07, 1.75)]; [AOR for severely stunted children aged 0-23 months = 1.50; 95 % CI: (1.05, 2.14)], [AOR for stunted children aged 0-59 months = 1.42; 95 % CI: (1.13, 1.79)] and [AOR for severely stunted children aged 0-59 months = 1.26; 95 % CI: (1.09, 1.46)]. Community-based interventions are needed to reduce the occurrence of stunting and severe stunting in Tanzania. These interventions should target mothers with low levels of education, male children, small- or average-size babies and households with unsafe drinking water
Metformin reduces airway glucose permeability and hyperglycaemia-induced Staphylococcus aureus load independently of effects on blood glucose
Background Diabetes is a risk factor for respiratory infection, and hyperglycaemia is associated with increased glucose in airway surface liquid and risk of Staphylococcus aureus infection.
Objectives To investigate whether elevation of basolateral/blood glucose concentration promotes airway Staphylococcus aureus growth and whether pretreatment with the antidiabetic drug metformin affects this relationship.
Methods Human airway epithelial cells grown at air–liquid interface (±18 h pre-treatment, 30 μM–1 mM metformin) were inoculated with 5×105 colony-forming units (CFU)/cm2 S aureus 8325-4 or JE2 or Pseudomonas aeruginosa PA01 on the apical surface and incubated for 7 h. Wild-type C57BL/6 or db/db (leptin receptor-deficient) mice, 6–10 weeks old, were treated with intraperitoneal phosphate-buffered saline or 40 mg/kg metformin for 2 days before intranasal inoculation with 1×107 CFU S aureus. Mice were culled 24 h after infection and bronchoalveolar lavage fluid collected.
Results Apical S aureus growth increased with basolateral glucose concentration in an in vitro airway epithelia–bacteria co-culture model. S aureus reduced transepithelial electrical resistance (RT) and increased paracellular glucose flux. Metformin inhibited the glucose-induced growth of S aureus, increased RT and decreased glucose flux. Diabetic (db/db) mice infected with S aureus exhibited a higher bacterial load in their airways than control mice after 2 days and metformin treatment reversed this effect. Metformin did not decrease blood glucose but reduced paracellular flux across ex vivo murine tracheas.
Conclusions Hyperglycaemia promotes respiratory S aureus infection, and metformin modifies glucose flux across the airway epithelium to limit hyperglycaemia-induced bacterial growth. Metformin might, therefore, be of additional benefit in the prevention and treatment of respiratory infection
Airway glucose concentrations and effect on growth of respiratory pathogens in cystic fibrosis
AbstractBackgroundPulmonary decline accelerates in cystic fibrosis-related diabetes (CFRD) proportional to severity of glucose intolerance, but mechanisms are unclear. In people without CF, airway glucose (AG) concentrations are elevated when blood glucose (BG)≥8 mmol L−1 (airway threshold), and are associated with acquisition of respiratory infection.MethodsTo determine the relationship between BG and AG, 40 CF patients underwent paired BG and AG (nasal) measurements. Daily time with BG>airway threshold was compared in 10 CFRD, 10 CF patients with normal glucose tolerance (CF-NGT) and 10 healthy volunteers by continuous BG monitoring. The effect of glucose at airway concentrations on bacterial growth was determined in vitro by optical densitometry.ResultsAG was present more frequently (85%-vs.-19%, p<0.0001) and at higher concentrations (0.5–3 mmol L−1-vs.-0.5–1 mmol L−1, p<0.0001) when BG was ≥8 mmol L−1-vs.-<8 mmol L−1. Daily time with BG≥8 mmol L−1 was CFRD (49±25%), CF-NGT (6±5%), healthy volunteers (1±3%), p<0.0001. Staphylococcus aureus growth increased at ≥0.5 mmol L−1 (p=0.006) and Pseudomonas aeruginosa growth above 1–4 mmol L−1 glucose (p=0.039).ConclusionsBG≥8 mmol L−1 predicted elevated AG concentrations in CF, at least in nasal secretions. CFRD patients spent ∼ 50% day with BG>airway threshold, implying persistently elevated AG concentrations. Further studies are required to determine whether elevated airway glucose concentrations contribute to accelerated pulmonary decline in CFRD
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