| 1. |
- Delabrouille, J., et al.
(författare)
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Exploring cosmic origins with CORE : Survey requirements and mission design
- 2018
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :4
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Tidskriftsartikel (refereegranskat)abstract
- Future observations of cosmic microwave background (CMB) polarisation have the potential to answer some of the most fundamental questions of modern physics and cosmology, including: what physical process gave birth to the Universe we see today? What are the dark matter and dark energy that seem to constitute 95% of the energy density of the Universe? Do we need extensions to the standard model of particle physics and fundamental interactions? Is the ACDM cosmological scenario correct, or are we missing an essential piece of the puzzle? In this paper, we list the requirements for a future CMB polarisation survey addressing these scientific objectives, and discuss the design drivers of the CORE space mission proposed to ESA in answer to the M5 call for a medium-sized mission. The rationale and options, and the methodologies used to assess the mission's performance, are of interest to other future CMB mission design studies. CORE has 19 frequency channels, distributed over a broad frequency range, spanning the 60-600 GHz interval, to control astrophysical foreground emission. The angular resolution ranges from 2' to 18', and the aggregate CMB sensitivity is about 2 mu K.arcmin. The observations are made with a single integrated focal-plane instrument, consisting of an array of 2100 cryogenically-cooled, linearly-polarised detectors at the focus of a 1.2-m aperture cross-Dragone telescope. The mission is designed to minimise all sources of systematic effects, which must be controlled so that no more than 10(-4) of the intensity leaks into polarisation maps, and no more than about 1% of E-type polarisation leaks into B-type modes. CORE observes the sky from a large Lissajous orbit around the Sun-Earth L2 point on an orbit that offers stable observing conditions and avoids contamination from sidelobe pick-up of stray radiation originating from the Sun, Earth, and Moon. The entire sky is observed repeatedly during four years of continuous scanning, with a combination of three rotations of the spacecraft over different timescales. With about 50% of the sky covered every few days, this scan strategy provides the mitigation of systematic effects and the internal redundancy that are needed to convincingly extract the primordial B-mode signal on large angular scales, and check with adequate sensitivity the consistency of the observations in several independent data subsets. CORE is designed as a near-ultimate CMB polarisation mission which, for optimal complementarity with ground-based observations, will perform the observations that are known to be essential to CMB polarisation science and cannot be obtained by any other means than a dedicated space mission. It will provide well-characterised, highly-redundant multi-frequency observations of polarisation at all the scales where foreground emission and cosmic variance dominate the final uncertainty for obtaining precision CMB science, as well as 2' angular resolution maps of high-frequency foreground emission in the 300-600 GHz frequency range, essential for complementarity with future ground-based observations with large telescopes that can observe the CMB with the same beamsize.
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| 2. |
- Finelli, F., et al.
(författare)
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Exploring cosmic origins with CORE : Inflation
- 2018
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; 2018:4
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Tidskriftsartikel (refereegranskat)abstract
- We forecast the scientific capabilities to improve our understanding of cosmic inflation of CORE, a proposed CMB space satellite submitted in response to the ESA fifth call for a medium-size mission opportunity. The CORE satellite will map the CMB anisotropies in temperature and polarization in 19 frequency channels spanning the range 60-600 GHz. CORE will have an aggregate noise sensitivity of 1.7 mu K.arcmin and an angular resolution of 5' at 200 GHz. We explore the impact of telescope size and noise sensitivity on the inflation science return by making forecasts for several instrumental configurations. This study assumes that the lower and higher frequency channels suffice to remove foreground contaminations and complements other related studies of component separation and systematic effects, which will be reported in other papers of the series Exploring Cosmic Origins with CORE. We forecast the capability to determine key inflationary parameters, to lower the detection limit for the tensor-to-scalar ratio down to the 10(-3) level, to chart the landscape of single field slow-roll inflationary models, to constrain the epoch of reheating, thus connecting inflation to the standard radiation-matter dominated Big Bang era, to reconstruct the primordial power spectrum, to constrain the contribution from isocurvature perturbations to the 10(-3) level, to improve constraints on the cosmic string tension to a level below the presumptive GUT scale, and to improve the current measurements of primordial non-Gaussianities down to the f(NL)(local) < 1 level. For all the models explored, CORE alone will improve significantly on the present constraints on the physics of inflation. Its capabilities will be further enhanced by combining with complementary future cosmological observations.
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| 5. |
- Blomqvist, L, et al.
(författare)
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Rectal tumours--MR imaging with endorectal and/or phased-array coils, and histopathological staging on giant sections. A comparative study
- 1997
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 38:3, s. 437-444
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Tidskriftsartikel (refereegranskat)abstract
- Objective: to investigate the accuracy of MR imaging in the preoperative staging of patients with clinically resectable rectal tumours. Material and Methods: Forty-eight consecutive patients with rectal tumours were examined, 29 with a pelvic phased-array coil and 19 with a multi-coil arrangement including a pelvic phased-array coil and an endorectal coil. MR images and histopatho-logical specimens and sections were reviewed independently and tumours were staged according to the TNM classification. Results: A more complete visualisation of the various layers of the rectal wall was achieved on the endorectal MR images than on the pelvic phased-array images. the sensitivity of MR in correctly staging T3 tumours compared with histopathology was 81% with a specificity of 82%. Penetration of the rectal wall was predicted with a sensitivity of 82% and a specificity of 87%. Sensitivity and specificity in predicting lymph node metastases was 83% and 74% respectively. Conclusion: MR imaging with both pelvic phased-array and endorectal coils allowed the preoperative staging of rectal tumours with a high degree of accuracy.
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| 14. |
- Fretwell, P., et al.
(författare)
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Bedmap2 : improved ice bed, surface and thickness datasets for Antarctica
- 2013
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 7:1, s. 375-393
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Tidskriftsartikel (refereegranskat)abstract
- We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 degrees S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km(3)) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.
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| 16. |
- Hindmarsh, T, et al.
(författare)
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One hundred years of neuroradiology in Acta Radiologica: a Swedish perspective
- 2021
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 62:11, s. 1451-1459
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Tidskriftsartikel (refereegranskat)abstract
- This year, Acta Radiologica marks its 100th anniversary. In this article, the authors present some of the highlights from the close collaboration between Swedish neuroradiology and Acta Radiologica over the last 100 years.
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| 19. |
- Kalliolia, Eirini, et al.
(författare)
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A 24-Hour Study of the Hypothalamo-Pituitary Axes in Huntington's Disease.
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:10
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease is an inherited neurodegenerative disorder characterised by motor, cognitive and psychiatric disturbances. Patients exhibit other symptoms including sleep and mood disturbances, muscle atrophy and weight loss which may be linked to hypothalamic pathology and dysfunction of hypothalamo-pituitary axes.
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| 20. |
- Kalliolia, Eirini, et al.
(författare)
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Plasma Melatonin Is Reduced in Huntington's Disease
- 2014
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Ingår i: Movement Disorders. - : Wiley. - 0885-3185 .- 1531-8257. ; 29:12, s. 1511-1515
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Tidskriftsartikel (refereegranskat)abstract
- This study was undertaken to determine whether the production of melatonin, a hormone regulating sleep in relation to the light/dark cycle, is altered in Huntington's disease. We analyzed the circadian rhythm of melatonin in a 24-hour study of cohorts of control, premanifest, and stage II/III Huntington's disease subjects. The mean and acrophase melatonin concentrations were significantly reduced in stage II/III Huntington's disease subjects compared with controls. We also observed a nonsignificant trend toward reduced mean and acrophase melatonin in premanifest Huntington's disease subjects. Onset of melatonin rise was significantly more temporally spread in both premanifest and stage II/III Huntington's disease subjects compared with controls. A nonsignificant trend also was seen for reduced pulsatile secretion of melatonin. Melatonin concentrations are reduced in Huntington's disease. Altered melatonin patterns may provide an explanation for disrupted sleep and circadian behavior in Huntington's disease, and represent a biomarker for disease state. Melatonin therapy may help the sleep disorders seen in Huntington's disease. (c) 2014 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
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| 24. |
- Li, TQ, et al.
(författare)
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Assessment of hepatic iron content using magnetic resonance imaging
- 2004
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 45:2, s. 119-129
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies over the past decade have shown that magnetic resonance imaging (MRI) has great potential for detecting and quantifying the distribution of iron in the body. With MRI, tissue iron is indirectly identified by the paramagnetic effects of iron on the shortening of water proton MR relaxation times. However, these effects are complex and involve a number of factors, such as tissue hydration, distribution of iron and water within the tissue, and the amount of iron loading within the iron storage molecules. A coherent understanding of how these factors influence the MRI signal is still lacking. The dependence on experimental conditions, such as magnet field strength, pulse sequences, and data acquisition parameters, further complicates iron quantification with MRI. To date, there is no generally accepted MRI approach available for clinical application. In this review, we first explain the basic MR relaxation mechanisms underlying the detection of iron with MRI. We then review the literature on empirical MRI studies of hepatic iron. Finally, we summarize the critical issues that need to be addressed to develop MRI techniques for non‐invasive iron detection in the body.
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| 25. |
- Li, TQ, et al.
(författare)
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Diffusion-weighted MR imaging of acute cerebral ischemia
- 1998
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 39:5, s. 460-473
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Tidskriftsartikel (refereegranskat)abstract
- Diffusion-weighted MR imaging has been used in studies on experimental animal models and on patients with acute cerebral ischemia. Compared with CT and conventional MR techniques, diffusion-weighted imaging can provide earlier and more precise detection of the location and the extent of an ischemic lesion during the critical first few hours after the onset of stroke Quantitative apparent diffusion coefficient (ADC) mapping of the brain water can also be carried out by recording a series of diffusion-weighted images with different amplitudes of the displacement encoding gradients. ADC maps can provide important information about the extra- and intracellular water homeostasis. ADC reduction of the tissue water is one of the early signals of the pathophysiological cascade resulting from ischemic tissue injury. Diffusion MR imaging has become a valuable tool in stroke research. It may also prove a valuable tool in monitoring the efficiency of therapeutic effects in stroke patients It is our intention to provide an overview of the recent development in this area with emphasis on the diffusion-weighted MR techniques, and to discuss the possible underlying biophysical mechanisms responsible for the contrast of diffusion-weighted imaging
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| 28. |
- Nambron, Rajasree, et al.
(författare)
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A Metabolic Study of Huntington's Disease.
- 2016
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease patients have a number of peripheral manifestations suggestive of metabolic and endocrine abnormalities. We, therefore, investigated a number of metabolic factors in a 24-hour study of Huntington's disease gene carriers (premanifest and moderate stage II/III) and controls.
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| 33. |
- Stokes, Chris R., et al.
(författare)
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On the reconstruction of palaeo-ice sheets : Recent advances and future challenges
- 2015
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 125, s. 15-49
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Forskningsöversikt (refereegranskat)abstract
- Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding mechanisms of global climate change and associated sea-level fluctuations in the past, present and future. The significance of palaeo-ice sheets is further underlined by the broad range of disciplines concerned with reconstructing their behaviour, many of which have undergone a rapid expansion since the 1980s. In particular, there has been a major increase in the size and qualitative diversity of empirical data used to reconstruct and date ice sheets, and major improvements in our ability to simulate their dynamics in numerical ice sheet models. These developments have made it increasingly necessary to forge interdisciplinary links between sub-disciplines and to link numerical modelling with observations and dating of proxy records. The aim of this paper is to evaluate recent developments in the methods used to reconstruct ice sheets and outline some key challenges that remain, with an emphasis on how future work might integrate terrestrial and marine evidence together with numerical modelling. Our focus is on pan-ice sheet reconstructions of the last deglaciation, but regional case studies are used to illustrate methodological achievements, challenges and opportunities. Whilst various disciplines have made important progress in our understanding of ice-sheet dynamics, it is clear that data-model integration remains under-used, and that uncertainties remain poorly quantified in both empirically-based and numerical ice-Sheet reconstructions. The representation of past climate will continue to be the largest source of uncertainty for numerical modelling. As such, palaeo-observations are critical to constrain and validate modelling. State-of-the-art numerical models will continue to improve both in model resolution and in the breadth of inclusion of relevant processes, thereby enabling more accurate and more direct comparison with the increasing range of palaeo-observations. Thus, the capability is developing to use all relevant palaeo-records to more strongly constrain deglacial (and to a lesser extent pre-LGM) ice sheet evolution. In working towards that goal, the accurate representation of uncertainties is required for both constraint data and model outputs. Close cooperation between modelling and data-gathering communities is essential to ensure this capability is realised and continues to progress.
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