| 1. |
- Fomalont, E. B., et al.
(författare)
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THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
- 2015
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 808:1
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Tidskriftsartikel (refereegranskat)abstract
- A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.
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| 2. |
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| 3. |
- Matthews, L. D., et al.
(författare)
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The ALMA phasing system: A beamforming capability for ultra-high-resolution science at (sub)millimeter wavelengths
- 2018
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 130:983
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Tidskriftsartikel (refereegranskat)abstract
- The Atacama Millimeter/submillimeter Array (ALMA) Phasing Project (APP) has developed and deployed the hardware and software necessary to coherently sum the signals of individual ALMA antennas and record the aggregate sum in Very Long Baseline Interferometry (VLBI) Data Exchange Format. These beamforming capabilities allow the ALMA array to collectively function as the equivalent of a single large aperture and participate in global VLBI arrays. The inclusion of phased ALMA in current VLBI networks operating at (sub) millimeter wavelengths provides an order of magnitude improvement in sensitivity, as well as enhancements in u–v coverage and north–south angular resolution. The availability of a phased ALMA enables a wide range of new ultra-high angular resolution science applications, including the resolution of supermassive black holes on event horizon scales and studies of the launch and collimation of astrophysical jets. It also provides a high-sensitivity aperture that may be used for investigations such as pulsar searches at high frequencies. This paper provides an overview of the ALMA Phasing System design, implementation, and performance characteristics.
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| 4. |
- Espada, D., et al.
(författare)
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Star Formation Efficiencies at Giant Molecular Cloud Scales in the Molecular Disk of the Elliptical Galaxy NGC 5128 (Centaurus A)
- 2019
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 887:1
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Tidskriftsartikel (refereegranskat)abstract
- We present ALMA CO (1-0) observations toward the dust lane of the nearest elliptical and radio galaxy, NGC 5128 (Centaurus A), with high angular resolution (similar to 1 '', or 18 pc), including information from large to small spatial scales and total flux. We find a total molecular gas mass of 1.6 x 10(9) M-circle dot and reveal the presence of filamentary components more extended than previously seen, up to a radius of 4 kpc. We find that the global star formation rate is similar to 1 M-circle dot yr(-1), which yields a star formation efficiency (SFE) of 0.6 Gyr(-1) (depletion time tau = 1.5 Gyr), similar to those in disk galaxies. We show the most detailed view to date (40 pc resolution) of the relation between molecular gas and star formation within the stellar component of an elliptical galaxy, from a scale of several kiloparsecs to the circumnuclear region close to the powerful radio jet. Although on average the SFEs are similar to those of spiral galaxies, the circumnuclear disk (CND) presents SFEs of 0.3 Gyr(-1), lower by a factor of 4 than the outer disk. The low SFE in the CND is in contrast to the high SFEs found in the literature for the circumnuclear regions of some nearby disk galaxies with nuclear activity, probably as a result of larger shear motions and longer active galactic nucleus feedback. The higher SFEs in the outer disk suggest that only central molecular gas or filaments with sufficient density and strong shear motions will remain in similar to 1 Gyr, which will later result in the compact molecular distributions and low SFEs usually seen in other giant ellipticals with cold gas.
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| 5. |
- Wolffsohn, James S., et al.
(författare)
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IMI - Clinical Myopia Control Trials and Instrumentation Report
- 2019
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Ingår i: Investigative Ophthalmology and Visual Science. - : ASSOC RESEARCH VISION OPHTHALMOLOGY INC. - 0146-0404 .- 1552-5783. ; 60:3, s. M132-M160
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Tidskriftsartikel (refereegranskat)abstract
- The evidence-basis based on existing myopia control trials along with the supporting academic literature were reviewed; this informed recommendations on the outcomes suggested from clinical trials aimed at slowing myopia progression to show the effectiveness of treatments and the impact on patients. These outcomes were classified as primary (refractive error and/or axial length), secondary (patient reported outcomes and treatment compliance), and exploratory (peripheral refraction, accommodative changes, ocular alignment, pupil size, outdoor activity/lighting levels, anterior and posterior segment imaging, and tissue biomechanics). The currently available instrumentation, which the literature has shown to best achieve the primary and secondary outcomes, was reviewed and critiqued. Issues relating to study design and patient selection were also identified. These findings and consensus from the International Myopia Institute members led to final recommendations to inform future instrumentation development and to guide clinical trial protocols.
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| 6. |
- Luis, R. S., et al.
(författare)
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Demonstration of a 1 Pb/s spatial channel network node
- 2019
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Ingår i: IET Conference Publications. - : Institution of Engineering and Technology.
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate a petabit-class hierarchical SDM switching node with granularity from 10 Tb/s to 1 Pb/s. We address spatial bypassing network scenarios, optical channel grooming, spatial multiplex section protection switching, and optical channels using coupled and uncoupled spatial channels.
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| 8. |
- Mbelambela, E. P., et al.
(författare)
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Prevalence of chronic obstructive pulmonary disease (COPD) among Congolese cement workers exposed to cement dust, in Kongo Central Province
- 2018
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 25:35, s. 35074-35083
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Tidskriftsartikel (refereegranskat)abstract
- Chronic exposure to cement dust may induce adverse health effects, including a significant decrease in lung function. The study investigated whether the prevalence of COPD and respiratory symptoms was associated with working at different tasks exposed to varying levels of cement dust. The cross-sectional study was carried out among 223 exposed and 156 less exposed workers from two cement factories from November 20 to December 15, 2016 in DRC. Workers completed a questionnaire and spirometry was performed. Multivariate analysis was performed to evaluate the association between occupation exposed to cement dust, COPD, and respiratory symptoms, after adjustment for confounders. Morning cough and cough on most days for as much as 3 months each year were significantly higher in the exposed group (p < 0.05) (p = 0.001) than in the less exposed group. As compared to the less exposed group, the prevalence of COPD was higher among the exposed group, 28.2 and 9.6% respectively (p < 0.001). A significant association with COPD, aOR 14.49 (5.33; 39.40), aOR 3.37 (1.44; 7.89), and aOR 3.09 (1.58; 6.05) was found among cleaning, transportation, and production workers, respectively. Working at certain tasks exposed to cement dust is associated with the higher prevalence of COPD and respiratory symptoms. A greater risk is being among cleaning, transportation, and production workers. This suggests the necessity to prioritize the quality of preventive measures in each work area. RONS HL, 1988, BRITISH JOURNAL OF INDUSTRIAL MEDICINE, V45, P368
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