Planck pre-launch status: The optical system Tauber, J. A.; Norgaard-Nielsen, H. U.; Ade, P. A. R. ...
Astronomy and astrophysics (Berlin),
09/2010, Letnik:
520
Journal Article
Recenzirano
Planck is a scientific satellite that represents the next milestone in space-based research related to the cosmic microwave background, and in many other astrophysical fields. Planck was launched on ...14 May of 2009 and is now operational. The uncertainty in the optical response of its detectors is a key factor allowing Planck to achieve its scientific objectives. More than a decade of analysis and measurements have gone into achieving the required performances. In this paper, we describe the main aspects of the Planck optics that are relevant to science, and the estimated in-flight performance, based on the knowledge available at the time of launch. We also briefly describe the impact of the major systematic effects of optical origin, and the concept of in-flight optical calibration. Detailed discussions of related areas are provided in accompanying papers.
Summary
Objective: To assess the prevalence of low serum high‐density lipoprotein cholesterol (HDL‐C) concentration and the relationship between HDL‐C and established cardiovascular disease (CVD) in ...an elderly Mediterranean population.
Methods: Analysis of Prevención del Riesgo de Ictus, a population‐based study on Spanish subjects aged ≥ 60 years. Low HDL‐C was defined following the European guidelines for cardiovascular prevention men: < 40 mg/dl (< 1.0 mmol/l); women: < 46 mg/dl (< 1.2 mmol/l). The relationship between low HDL‐C or HDL‐C concentration (in quintiles) and CVD was assessed through multivariate models that included cardiovascular risk factors, statins and subclinical organ damage.
Results: On 6010 subjects (71.7 years, 53.5% women), low HDL‐C was present in 17.5% 95% confidence interval (CI): 16.5–18.5 and was more frequent in women 20.4% (19.0–21.8) vs. 14.1% (12.8–15.4) in men p < 0.001 and in patients with diabetes, CVD or statin therapy. Low HDL‐C was independently associated with CVD adjusted odds ratio (OR): 1.46, 95% CI: 1.22–1.74, p < 0.001. The prevalence of CVD was higher as HDL‐C concentration was lower (chi‐square trend < 0.001). Compared with the highest quintile > 65 mg/dl (> 1.67 mmol/l), adjusted OR for CVD were 1.39 (1.10–1.76), 1.41 (1.11–1.80), 1.49 (1.18–1.89) and 1.91 (1.52–2.39), respectively for those in the fourth 57–65 mg/dl (1.46–1.67 mmol/l), third 51–56 mg/dl (1.31–1.45 mmol/l), second 46–50 mg/dl (1.18–1.30 mmol/l) and first < 46 mg/dl (< 1.18 mmol/l) quintiles of HDL‐C. This association was seen in males and females.
Conclusions: A total of 17.5% of this Spanish population aged ≥ 60 years had low HDL‐C. We found a strong, independent and inverse association between HDL‐C concentrations and established CVD, even at ranges of HDL‐C considered as normal.
In this paper, the authors present a method to reconstruct measured antenna radiation patterns and their related time-varying aperture fields. The method is based on a model that accounts for the ...measurement scenario and the antenna radiation characteristics through its radiation centers. The inputs to the model are radiation pattern measurements over a certain bandwidth. Solving the model provides the number of radiation centers, the patterns coupled with each radiation center, and the time delay at which these patterns would be measured. With this information one can reconstruct the measured pattern and retrieve the time-varying aperture fields of the antenna. The latter also provides a diagnostic tool for complex radiating structures. The method and the model are validated with measurements performed in a compact range of two spaceborne antennas.
In this paper we present the Low Frequency Instrument (LFI), designed and developed as part of the Planck space mission, the ESA programme dedicated to precision imaging of the cosmic microwave ...background (CMB). Planck-LFI will observe the full sky in intensity and polarisation in three frequency bands centred at 30, 44 and 70 GHz, while higher frequencies (100–850 GHz) will be covered by the HFI instrument. The LFI is an array of microwave radiometers based on state-of-the-art indium phosphide cryogenic HEMT amplifiers implemented in a differential system using blackbody loads as reference signals. The front end is cooled to 20 K for optimal sensitivity and the reference loads are cooled to 4 K to minimise low-frequency noise. We provide an overview of the LFI, discuss the leading scientific requirements, and describe the design solutions adopted for the various hardware subsystems. The main drivers of the radiometric, optical, and thermal design are discussed, including the stringent requirements on sensitivity, stability, and rejection of systematic effects. Further details on the key instrument units and the results of ground calibration are provided in a set of companion papers.
A major challenge in updating clinical guidelines is to efficiently identify new, relevant evidence. We evaluated the efficiency and feasibility of two new approaches: the development of restrictive ...search strategies using PubMed Clinical Queries for MEDLINE and the use of the PLUS (McMaster Premium Literature Service) database.
We evaluated a random sample of recommendations from a national guideline development program and identified the references that would potentially trigger an update (key references) using an exhaustive approach. We designed restrictive search strategies using the minimum number of Medical Subject Headings (MeSH) terms and text words required from the original exhaustive search strategies and applying broad and narrow filters. We developed PLUS search strategies, matching Medical Subject Headings (MeSH) and Systematized Nomenclature of Medicine (SNOMED) terms with guideline topics. We compared the number of key references retrieved by these approaches with those retrieved by the exhaustive approach.
The restrictive approach retrieved 68.1 % fewer references than the exhaustive approach (12,486 versus 39,136), and identified 89.9 % (62/69) of key references and 88 % (22/25) of recommendation updates. The use of PLUS retrieved 88.5 % fewer references than the exhaustive approach (4,486 versus 39,136) and identified substantially fewer key references (18/69, 26.1 %) and fewer recommendation updates (10/25, 40 %).
The proposed restrictive approach is a highly efficient and feasible method to identify new evidence that triggers a recommendation update. Searching only in the PLUS database proved to be a suboptimal approach and suggests the need for topic-specific tailoring.
Time domain holography from direct time domain far field measurements is presented as a novel, fast approach to antenna diagnostics, which offers a greater insight into the electrical properties of ...antennas than that possible using standard frequency domain holography. Experimental results from one array antenna measured in a compact range are presented which illustrate the effectiveness of the new approach.
Measuring radiation patterns in the time domain provides the antenna characteristics over a wide-frequency spectrum in a single measurement. Such an advantage over traditional measurements in the ...frequency domain makes the practical implementation of time-domain measurements in compact ranges particularly attractive. In this paper, the time-varying performance of the compact range's quiet zone and plane-wave spectrum are analyzed and supported with simulations. This feasibility study preceded the implementation of a time-domain measurement system in the compact antenna test range of the European Space Research and Technology Center. Measurement results of a linear array are also presented to illustrate the new capabilities of the compact range.
The Scientific Societies of Primary Care, being the area in which there is a considerable prevalence of Arterial Hypertension (AHT), need to periodically evaluate the international guidelines for its ...management. This is particularly relevant when disparate guidelines make it difficult to make decisions in daily clinical practice. The present document has as its aim to analyse the changes and new developments proposed in the guidelines of the American College of Cardiology and the American Heart Association (ACC/AHA 2017), as well as in the guidelines of the European Society of Cardiology and European Society of Hypertension (ESC/ESH 2018). An analysis will be made of any differences, limitations, and their applicability to Primary Care in Spain. Finally, the most relevant available and appropriate information is extracted and integrated in order to homogenise the care of the hypertensive patient, from a critical, but also a reasoned, perspective. The discrepancies between the recommendations in such essential aspects as the management of the disease, require the compiling and critical analysis of the information that enables us as scientific society, interested in providing all PC physicians with the most relevant, and at the same time, sensible, recommendations of all the guidelines.
Time domain antenna holography Martí-Canales, J; Ligthart, L P
Electronics letters,
03/2000, Letnik:
36, Številka:
6
Journal Article
Recenzirano
Time domain holography from direct time domain far field measurements is presented as a novel, fast approach to antenna diagnostics, which offers a greater insight into the electrical properties of ...antennas than that possible using a standard frequency domain holography. Experimental results from one array antenna measured in a compact range are presented which illustrate the effectiveness of the new approach.
Radar cross-section measurements in the time domain are performed, for the very first time, over a compact range. Apart from the hardware configuration and calibration used, extended analysis ...capabilities are discussed and illustrated with measurements. An enormous potential is envisaged in industrial and military applications, e.g. reverse engineering, radome optimisation and stealth design.
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