| 1. |
- van Cappellen, W., et al.
(author)
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Apertif: Phased array feeds for the Westerbork Synthesis Radio Telescope: System overview and performance characteristics
- 2022
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 658
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Journal article (peer-reviewed)abstract
- We describe the APERture Tile In Focus (Apertif) system, a phased array feed (PAF) upgrade of the Westerbork Synthesis Radio Telescope that transforms this telescope into a high-sensitivity, wide-field-of-view L-band imaging and transient survey instrument. Using novel PAF technology, up to 40 partially overlapping beams are formed on the sky simultaneously, significantly increasing the survey speed of the telescope. With this upgraded instrument, an imaging survey covering an area of 2300 deg2 is being performed that will deliver both continuum and spectral line datasets, of which the first data have been publicly released. In addition, a time domain transient and pulsar survey covering 15 000 deg2 is in progress. An overview of the Apertif science drivers, hardware, and software of the upgraded telescope is presented, along with its key performance characteristics.
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| 2. |
- van Haarlem, M. P., et al.
(author)
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LOFAR : The LOw-Frequency ARray
- 2013
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 556, s. 1-53
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Journal article (peer-reviewed)abstract
- LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10–240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR’s new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory.
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| 3. |
- Heald, G. H., et al.
(author)
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The LOFAR Multifrequency Snapshot Sky Survey (MSSS) : I. Survey description and first results
- 2015
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 582, s. 1-22
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Journal article (peer-reviewed)abstract
- We present the Multifrequency Snapshot Sky Survey (MSSS), the first northern-sky Low Frequency Array (LOFAR) imaging survey. In this introductory paper, we first describe in detail the motivation and design of the survey. Compared to previous radio surveys, MSSS is exceptional due to its intrinsic multifrequency nature providing information about the spectral properties of the detected sources over more than two octaves (from 30 to 160 MHz). The broadband frequency coverage, together with the fast survey speed generated by LOFAR’s multibeaming capabilities, make MSSS the first survey of the sort anticipated to be carried out with the forthcoming Square Kilometre Array (SKA). Two of the sixteen frequency bands included in the survey were chosen to exactly overlap the frequency coverage of large-area Very Large Array (VLA) and Giant Metrewave Radio Telescope (GMRT) surveys at 74 MHz and 151 MHz respectively. The survey performance is illustrated within the MSSS Verification Field (MVF), a region of 100 square degrees centered at (α,δ)J2000 = (15h,69°). The MSSS results from the MVF are compared with previous radio survey catalogs. We assess the flux and astrometric uncertainties in the catalog, as well as the completeness and reliability considering our source finding strategy. We determine the 90% completeness levels within the MVF to be 100 mJy at 135 MHz with 108″ resolution, and 550 mJy at 50 MHz with 166″ resolution. Images and catalogs for the full survey, expected to contain 150 000–200 000 sources, will be released to a public web server. We outline the plans for the ongoing production of the final survey products, and the ultimate public release of images and source catalogs.
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| 6. |
- Batkovskyte, D., et al.
(author)
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Al-Gazali Skeletal Dysplasia Constitutes the Lethal End of ADAMTSL2-Related Disorders
- 2023
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In: Journal of Bone and Mineral Research. - : Wiley. - 0884-0431 .- 1523-4681. ; 38:5, s. 692-706
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Journal article (peer-reviewed)abstract
- Lethal short-limb skeletal dysplasia Al-Gazali type (OMIM %601356), also called dysplastic cortical hyperostosis, Al-Gazali type, is an ultra-rare disorder previously reported in only three unrelated individuals. The genetic etiology for Al-Gazali skeletal dysplasia has up until now been unknown. Through international collaborative efforts involving seven clinical centers worldwide, a cohort of nine patients with clinical and radiographic features consistent with short-limb skeletal dysplasia Al-Gazali type was collected. The affected individuals presented with moderate intrauterine growth restriction, relative macrocephaly, hypertrichosis, large anterior fontanelle, short neck, short and stiff limbs with small hands and feet, severe brachydactyly, and generalized bone sclerosis with mild platyspondyly. Biallelic disease-causing variants in ADAMTSL2 were detected using massively parallel sequencing (MPS) and Sanger sequencing techniques. Six individuals were compound heterozygous and one individual was homozygous for pathogenic variants in ADAMTSL2. In one of the families, pathogenic variants were detected in parental samples only. Overall, this study sheds light on the genetic cause of Al-Gazali skeletal dysplasia and identifies it as a semi-lethal part of the spectrum of ADAMTSL2-related disorders. Furthermore, we highlight the importance of meticulous analysis of the pseudogene region of ADAMTSL2 where disease-causing variants might be located.
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| 9. |
- Artigas, J., et al.
(author)
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Towards a renewed research agenda in ecotoxicology
- 2012
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In: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 160, s. 201-206
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Journal article (peer-reviewed)abstract
- New concerns about biodiversity, ecosystem services and human health triggered several new regulations increasing the need for sound ecotoxicological risk assessment. The PEER network aims to share its view on the research issues that this challenges. PEER scientists call for an improved biologically relevant exposure assessment. They promote comprehensive effect assessment at several biological levels. Biological traits should be used for Environmental risk assessment (ERA) as promising tools to better understand relationships between structure and functioning of ecosystems. The use of modern high throughput methods could also enhance the amount of data for a better risk assessment. Improved models coping with multiple stressors or biological levels are necessary to answer for a more scientifically based risk assessment. Those methods must be embedded within life cycle analysis or economical models for efficient regulations. Joint research programmes involving humanities with ecological sciences should be developed for a sound risk management. (C) 2011 Elsevier Ltd. All rights reserved.
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| 10. |
- Arts, M. J., et al.
(author)
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Analysis of the EMBRACE aperture array antenna by the characteristic Basis Function Method
- 2011
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In: Proceedings - 13th International Conference on Electromagnetics in Advanced Applications, ICEAA'11, Torino, 12-16 September 2011. - 9781612849782 ; , s. 959-962
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Conference paper (peer-reviewed)abstract
- This paper describes the use of the Characteristic Basis Function Method for the simulation of large phased array antennas for radio astronomy. It will be shown how the antenna effective area and the receiver noise temperature depend on array size. Also the receiving sensitivity Aeff /T sys normalised with respect to the physical area of the array will be shown for different array sizes and scan angles.
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| 11. |
- Benthem, P., et al.
(author)
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Aperture array development for future large radio telescopes
- 2011
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In: European Conference on Antennas and Propagation 2011, 11-15 April 2011, Rome.
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Conference paper (peer-reviewed)abstract
- We present the design of a phased array system for future radio telescopes. This includes a system overview and recent results of the designed and implemented system, the Electronic Multi-Beam Radio Astronomy Concept (EMBRACE). Furthermore, simulations with a full-EM antenna simulator, combined with measurements on actual hardware, will provide information for the next design step, the Aperture Array Verification System (AAVS). With AAVS, we will prove design readiness of this novel array technology.
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| 15. |
- Ivashina, Marianna, 1975, et al.
(author)
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An axi-symmetric segmented composite SKA dish design: Performance and production analysis
- 2011
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In: Asia-Pacific Microwave Conference, APMC 2011; Melbourne, VIC; 5 - 8 December 2011. - 9780858259744 ; , s. 1182-1185
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Conference paper (peer-reviewed)abstract
- A concept of an axi-symmetric dish as antenna reflector for the next generation radio telescope - the Square Kilometre Array (SKA) - is presented. The reflector is based on the use of novel thermoplastic composite material (reinforced with carbon fibre) in the context of the telescope design with wide band single pixel feeds. The baseline of this design represents an array of 100's to 1000's reflector antennas of 15-m diameter and covers frequencies from
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| 16. |
- Jansen, Jurgen, et al.
(author)
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Functional analysis of monocarboxylate transporter 8 mutations identified in patients with X-linked psychomotor retardation and elevated serum triiodothyronine
- 2007
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In: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 92:6, s. 2378-2381
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Journal article (peer-reviewed)abstract
- Context: T-3 action in neurons is essential for brain development. Recent evidence indicates that monocarboxylate transporter 8 (MCT8) is important for neuronal T-3 uptake. Hemizygous mutations have been identified in the X-linked MCT8 gene in boys with severe psychomotor retardation and elevated serum T-3 levels. Objective: The objective of this study was to determine the functional consequences of MCT8 mutations regarding transport of T-3. Design: MCT8 function was studied in wild-type or mutant MCT8-transfected JEG3 cells by analyzing: 1) T-3 uptake, 2) T-3 metabolism in cells cotransfected with human type 3 deiodinase, 3) immunoblotting, and 4) immunocytochemistry. Results: The mutations identified in MCT8 comprise four deletions (24.5 kb, 2.4 kb, 14 bp, and 3 bp), three missense mutations (Ala224Val, Arg271His, and Leu471Pro), a nonsense mutation (Arg245stop), and a splice site mutation (94 amino acid deletion). All tested mutants were inactive in uptake and metabolism assays, except MCT8 Arg271His, which showed approximately 20% activity vs. wild-type MCT8. Conclusion: These findings support the hypothesis that the severe psychomotor retardation and elevated serum T-3 levels in these patients are caused by inactivation of the MCT8 transporter, preventing action and metabolism of T-3 in central neurons.
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| 17. |
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| 18. |
- Scarpellini, E., et al.
(author)
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International consensus on the diagnosis and management of dumping syndrome
- 2020
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In: Nature Reviews Endocrinology. - : Springer Science and Business Media LLC. - 1759-5029 .- 1759-5037. ; 16:8, s. 448-466
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Journal article (peer-reviewed)abstract
- Dumping syndrome is a common but underdiagnosed complication of gastric and oesophageal surgery. We initiated a Delphi consensus process with international multidisciplinary experts. We defined the scope, proposed statements and searched electronic databases to survey the literature. Eighteen experts participated in the literature summary and voting process evaluating 62 statements. We evaluated the quality of evidence using grading of recommendations assessment, development and evaluation (GRADE) criteria. Consensus (defined as >80% agreement) was reached for 33 of 62 statements, including the definition and symptom profile of dumping syndrome and its effect on quality of life. The panel agreed on the pathophysiological relevance of rapid passage of nutrients to the small bowel, on the role of decreased gastric volume capacity and release of glucagon-like peptide 1. Symptom recognition is crucial, and the modified oral glucose tolerance test, but not gastric emptying testing, is useful for diagnosis. An increase in haematocrit >3% or in pulse rate >10 bpm 30 min after the start of the glucose intake are diagnostic of early dumping syndrome, and a nadir hypoglycaemia level <50 mg/dl is diagnostic of late dumping syndrome. Dietary adjustment is the agreed first treatment step; acarbose is effective for late dumping syndrome symptoms and somatostatin analogues are preferred for patients who do not respond to diet adjustments and acarbose. Dumping syndrome is a frequent complication of oesophageal and gastric surgery, as well as bariatric surgery; however, guidance on how to manage patients with this condition is lacking. In this Evidence-based guideline, the authors use a Delphi consensus process to develop uniform guidance for the definition, diagnosis and management of dumping syndrome.
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