| 1. |
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| 2. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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| 3. |
- Abadie, J., et al.
(författare)
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Implementation and testing of the first prompt search for gravitational wave transients with electromagnetic counterparts
- 2012
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 539
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Tidskriftsartikel (refereegranskat)abstract
- Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations. Methods. During two observing periods (Dec. 17, 2009 to Jan. 8, 2010 and Sep. 2 to Oct. 20, 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly. Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with similar to 50% or better probability with a few pointings of wide-field telescopes.
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| 4. |
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| 5. |
- Hay, S. I., et al.
(författare)
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Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990-2016 : A systematic analysis for the Global Burden of Disease Study 2016
- 2017
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Ingår i: The Lancet. - : Lancet Publishing Group. - 0140-6736 .- 1474-547X. ; 390:10100, s. 1260-1344
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Tidskriftsartikel (refereegranskat)abstract
- Background: Measurement of changes in health across locations is useful to compare and contrast changing epidemiological patterns against health system performance and identify specific needs for resource allocation in research, policy development, and programme decision making. Using the Global Burden of Diseases, Injuries, and Risk Factors Study 2016, we drew from two widely used summary measures to monitor such changes in population health: disability-adjusted life-years (DALYs) and healthy life expectancy (HALE). We used these measures to track trends and benchmark progress compared with expected trends on the basis of the Socio-demographic Index (SDI). Methods: We used results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016 for all-cause mortality, cause-specific mortality, and non-fatal disease burden to derive HALE and DALYs by sex for 195 countries and territories from 1990 to 2016. We calculated DALYs by summing years of life lost and years of life lived with disability for each location, age group, sex, and year. We estimated HALE using age-specific death rates and years of life lived with disability per capita. We explored how DALYs and HALE difered from expected trends when compared with the SDI: the geometric mean of income per person, educational attainment in the population older than age 15 years, and total fertility rate. Findings: The highest globally observed HALE at birth for both women and men was in Singapore, at 75·2 years (95% uncertainty interval 71·9-78·6) for females and 72·0 years (68·8-75·1) for males. The lowest for females was in the Central African Republic (45·6 years [42·0-49·5]) and for males was in Lesotho (41·5 years [39·0-44·0]). From 1990 to 2016, global HALE increased by an average of 6·24 years (5·97-6·48) for both sexes combined. Global HALE increased by 6·04 years (5·74-6·27) for males and 6·49 years (6·08-6·77) for females, whereas HALE at age 65 years increased by 1·78 years (1·61-1·93) for males and 1·96 years (1·69-2·13) for females. Total global DALYs remained largely unchanged from 1990 to 2016 (-2·3% [-5·9 to 0·9]), with decreases in communicable, maternal, neonatal, and nutritional (CMNN) disease DALYs ofset by increased DALYs due to non-communicable diseases (NCDs). The exemplars, calculated as the fve lowest ratios of observed to expected age-standardised DALY rates in 2016, were Nicaragua, Costa Rica, the Maldives, Peru, and Israel. The leading three causes of DALYs globally were ischaemic heart disease, cerebrovascular disease, and lower respiratory infections, comprising 16·1% of all DALYs. Total DALYs and age-standardised DALY rates due to most CMNN causes decreased from 1990 to 2016. Conversely, the total DALY burden rose for most NCDs; however, age-standardised DALY rates due to NCDs declined globally. Interpretation: At a global level, DALYs and HALE continue to show improvements. At the same time, we observe that many populations are facing growing functional health loss. Rising SDI was associated with increases in cumulative years of life lived with disability and decreases in CMNN DALYs ofset by increased NCD DALYs. Relative compression of morbidity highlights the importance of continued health interventions, which has changed in most locations in pace with the gross domestic product per person, education, and family planning. The analysis of DALYs and HALE and their relationship to SDI represents a robust framework with which to benchmark location-specific health performance. Country-specific drivers of disease burden, particularly for causes with higher-than-expected DALYs, should inform health policies, health system improvement initiatives, targeted prevention eforts, and development assistance for health, including fnancial and research investments for all countries, regardless of their level of sociodemographic development. The presence of countries that substantially outperform others suggests the need for increased scrutiny for proven examples of best practices, which can help to extend gains, whereas the presence of underperforming countries suggests the need for devotion of extra attention to health systems that need more robust support. © The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.
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| 6. |
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| 7. |
- Vos, T., et al.
(författare)
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Global, regional, and national incidence, prevalence, and years lived with disability for 328 diseases and injuries for 195 countries, 1990-2016: a systematic analysis for the Global Burden of Disease Study 2016
- 2017
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Ingår i: Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 390:10100, s. 1211-1259
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Tidskriftsartikel (refereegranskat)abstract
- Background As mortality rates decline, life expectancy increases, and populations age, non-fatal outcomes of diseases and injuries are becoming a larger component of the global burden of disease. The Global Burden of Diseases, Injuries, and Risk Factors Study 2016 (GBD 2016) provides a comprehensive assessment of prevalence, incidence, and years lived with disability (YLDs) for 328 causes in 195 countries and territories from 1990 to 2016. Methods We estimated prevalence and incidence for 328 diseases and injuries and 2982 sequelae, their non-fatal consequences. We used DisMod-MR 2.1, a Bayesian meta-regression tool, as the main method of estimation, ensuring consistency between incidence, prevalence, remission, and cause of death rates for each condition. For some causes, we used alternative modelling strategies if incidence or prevalence needed to be derived from other data. YLDs were estimated as the product of prevalence and a disability weight for all mutually exclusive sequelae, corrected for comorbidity and aggregated to cause level. We updated the Socio-demographic Index (SDI), a summary indicator of income per capita, years of schooling, and total fertility rate. GBD 2016 complies with the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER). Findings Globally, low back pain, migraine, age-related and other hearing loss, iron-deficiency anaemia, and major depressive disorder were the five leading causes of YLDs in 2016, contributing 57.6 million (95% uncertainty interval [UI] 40.8-75.9 million [7.2%, 6.0-8.3]), 45.1 million (29.0-62.8 million [5.6%, 4.0-7.2]), 36.3 million (25.3-50.9 million [4.5%, 3.8-5.3]), 34.7 million (23.0-49.6 million [4.3%, 3.5-5.2]), and 34.1 million (23.5-46.0 million [4.2%, 3.2-5.3]) of total YLDs, respectively. Age-standardised rates of YLDs for all causes combined decreased between 1990 and 2016 by 2.7% (95% UI 2.3-3.1). Despite mostly stagnant age-standardised rates, the absolute number of YLDs from non-communicable diseases has been growing rapidly across all SDI quintiles, partly because of population growth, but also the ageing of populations. The largest absolute increases in total numbers of YLDs globally were between the ages of 40 and 69 years. Age-standardised YLD rates for all conditions combined were 10.4% (95% UI 9.0-11.8) higher in women than in men. Iron-deficiency anaemia, migraine, Alzheimer's disease and other dementias, major depressive disorder, anxiety, and all musculoskeletal disorders apart from gout were the main conditions contributing to higher YLD rates in women. Men had higher age-standardised rates of substance use disorders, diabetes, cardiovascular diseases, cancers, and all injuries apart from sexual violence. Globally, we noted much less geographical variation in disability than has been documented for premature mortality. In 2016, there was a less than two times difference in age-standardised YLD rates for all causes between the location with the lowest rate (China, 9201 YLDs per 100 000, 95% UI 6862-11943) and highest rate (Yemen, 14 774 YLDs per 100 000, 11 018-19 228). Interpretation The decrease in death rates since 1990 for most causes has not been matched by a similar decline in age-standardised YLD rates. For many large causes, YLD rates have either been stagnant or have increased for some causes, such as diabetes. As populations are ageing, and the prevalence of disabling disease generally increases steeply with age, health systems will face increasing demand for services that are generally costlier than the interventions that have led to declines in mortality in childhood or for the major causes of mortality in adults. Up-todate information about the trends of disease and how this varies between countries is essential to plan for an adequate health-system response. Copyright (C) The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.
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| 8. |
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| 9. |
- Petroff, E., et al.
(författare)
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A polarized fast radio burst at low Galactic latitude
- 2017
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford Academic. - 0035-8711 .- 1365-2966. ; 469:4, s. 4465-4482
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Tidskriftsartikel (refereegranskat)abstract
- We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 +/- 0.8 pc cm(-3), a pulse duration of 2.8(-0.5)(+1.2) ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7(-0.1)(+0.2) Jy. The FRB originated at a Galactic longitude and latitude of 24.66 degrees, 5.28 degrees and 25 degrees away from the Galactic Center. The burst was found to be 43 +/- 5 per cent linearly polarized with a rotation measure (RM) in the range -9 < RM < 12 rad m(-2) (95 per cent confidence level), consistent with zero. The burst was followed up with 11 telescopes to search for radio, optical, X-ray, gamma-ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 h of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.
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| 10. |
- Kinyoki, DK, et al.
(författare)
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Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
- 2020
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Ingår i: Nature medicine. - : Springer Science and Business Media LLC. - 1546-170X .- 1078-8956. ; 26:5, s. 750-759
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Tidskriftsartikel (refereegranskat)abstract
- A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic.
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| 11. |
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| 12. |
- Ackley, K., et al.
(författare)
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Observational constraints on the optical and near-infrared emission from the neutron star-black hole binary merger candidate S190814bv
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 643
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Tidskriftsartikel (refereegranskat)abstract
- Context. Gravitational wave (GW) astronomy has rapidly reached maturity, becoming a fundamental observing window for modern astrophysics. The coalescences of a few tens of black hole (BH) binaries have been detected, while the number of events possibly including a neutron star (NS) is still limited to a few. On 2019 August 14, the LIGO and Virgo interferometers detected a high-significance event labelled S190814bv. A preliminary analysis of the GW data suggests that the event was likely due to the merger of a compact binary system formed by a BH and a NS.Aims. In this paper, we present our extensive search campaign aimed at uncovering the potential optical and near infrared electromagnetic counterpart of S190814bv. We found no convincing electromagnetic counterpart in our data. We therefore use our non-detection to place limits on the properties of the putative outflows that could have been produced by the binary during and after the merger.Methods. Thanks to the three-detector observation of S190814bv, and given the characteristics of the signal, the LIGO and Virgo Collaborations delivered a relatively narrow localisation in low latency - a 50% (90%) credible area of 5 deg(2) (23 deg(2)) - despite the relatively large distance of 26752 Mpc. ElectromagNetic counterparts of GRAvitational wave sources at the VEry Large Telescope collaboration members carried out an intensive multi-epoch, multi-instrument observational campaign to identify the possible optical and near infrared counterpart of the event. In addition, the ATLAS, GOTO, GRAWITA-VST, Pan-STARRS, and VINROUGE projects also carried out a search on this event. In this paper, we describe the combined observational campaign of these groups.Results. Our observations allow us to place limits on the presence of any counterpart and discuss the implications for the kilonova (KN), which was possibly generated by this NS-BH merger, and for the strategy of future searches. The typical depth of our wide-field observations, which cover most of the projected sky localisation probability (up to 99.8%, depending on the night and filter considered), is r similar to 22 (resp. K similar to 21) in the optical (resp. near infrared). We reach deeper limits in a subset of our galaxy-targeted observations, which cover a total similar to 50% of the galaxy-mass-weighted localisation probability. Altogether, our observations allow us to exclude a KN with large ejecta mass M greater than or similar to 0.1 M-circle dot to a high (> 90%) confidence, and we can exclude much smaller masses in a sub-sample of our observations. This disfavours the tidal disruption of the neutron star during the merger.Conclusions. Despite the sensitive instruments involved in the campaign, given the distance of S190814bv, we could not reach sufficiently deep limits to constrain a KN comparable in luminosity to AT 2017gfo on a large fraction of the localisation probability. This suggests that future (likely common) events at a few hundred megaparsecs will be detected only by large facilities with both a high sensitivity and large field of view. Galaxy-targeted observations can reach the needed depth over a relevant portion of the localisation probability with a smaller investment of resources, but the number of galaxies to be targeted in order to get a fairly complete coverage is large, even in the case of a localisation as good as that of this event.
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| 13. |
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| 14. |
- Stappers, B. W., et al.
(författare)
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Observing pulsars and fast transients with LOFAR
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 530
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Tidskriftsartikel (refereegranskat)abstract
- Low frequency radio waves, while challenging to observe, are a rich source of information about pulsars. The LOw Frequency ARray (LOFAR) is a new radio interferometer operating in the lowest 4 octaves of the ionospheric "radio window": 10-240 MHz, that will greatly facilitate observing pulsars at low radio frequencies. Through the huge collecting area, long baselines, and flexible digital hardware, it is expected that LOFAR will revolutionize radio astronomy at the lowest frequencies visible from Earth. LOFAR is a next-generation radio telescope and a pathfinder to the Square Kilometre Array (SKA), in that it incorporates advanced multi-beaming techniques between thousands of individual elements. We discuss the motivation for low-frequency pulsar observations in general and the potential of LOFAR in addressing these science goals. We present LOFAR as it is designed to perform high-time-resolution observations of pulsars and other fast transients, and outline the various relevant observing modes and data reduction pipelines that are already or will soon be implemented to facilitate these observations. A number of results obtained from commissioning observations are presented to demonstrate the exciting potential of the telescope. This paper outlines the case for low frequency pulsar observations and is also intended to serve as a reference for upcoming pulsar/fast transient science papers with LOFAR.
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| 15. |
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| 16. |
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| 17. |
- Wang, HD, et al.
(författare)
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Global, regional, national, and selected subnational levels of stillbirths, neonatal, infant, and under-5 mortality, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015
- 2016
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Ingår i: Lancet (London, England). - : Elsevier. - 1474-547X .- 0140-6736. ; 388:10053, s. 1725-1774
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Tidskriftsartikel (refereegranskat)
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| 18. |
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| 19. |
- Osborn, H. P., et al.
(författare)
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The PDS 110 observing campaign - photometric and spectroscopic observations reveal eclipses are aperiodic
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 485:2, s. 1614-1625
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Tidskriftsartikel (refereegranskat)abstract
- PDS 110 is a young disc-hosting star in the Orion OB1A association. Two dimming events of similar depth and duration were seen in 2008 (WASP) and 2011 (KELT), consistent with an object in a closed periodic orbit. In this paper, we present data from a ground-based observing campaign designed to measure the star both photometrically and spectroscopically during the time of predicted eclipse in 2017 September. Despite high-quality photometry, the predicted eclipse did not occur, although coherent structure is present suggesting variable amounts of stellar flux or dust obscuration. We also searched for radial velocity (RV) oscillations caused by any hypothetical companion and can rule out close binaries to 0.1Ms. Asearch of Sonneberg plate archive data also enabled us to extend the photometric baseline of this star back more than 50 yr, and similarly does not re-detect any deep eclipses. Taken together, they suggest that the eclipses seen in WASP and KELT photometry were due to aperiodic events. It would seem that PDS 110 undergoes stochastic dimmings that are shallower and of shorter duration than those of UX Ori variables, but may have a similar mechanism.
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| 20. |
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| 21. |
- Wang, Haidong, et al.
(författare)
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Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015 : a systematic analysis for the Global Burden of Disease Study 2015
- 2016
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 388:10053, s. 1459-1544
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Improving survival and extending the longevity of life for all populations requires timely, robust evidence on local mortality levels and trends. The Global Burden of Disease 2015 Study (GBD 2015) provides a comprehensive assessment of all-cause and cause-specific mortality for 249 causes in 195 countries and territories from 1980 to 2015. These results informed an in-depth investigation of observed and expected mortality patterns based on sociodemographic measures.METHODS: We estimated all-cause mortality by age, sex, geography, and year using an improved analytical approach originally developed for GBD 2013 and GBD 2010. Improvements included refinements to the estimation of child and adult mortality and corresponding uncertainty, parameter selection for under-5 mortality synthesis by spatiotemporal Gaussian process regression, and sibling history data processing. We also expanded the database of vital registration, survey, and census data to 14 294 geography-year datapoints. For GBD 2015, eight causes, including Ebola virus disease, were added to the previous GBD cause list for mortality. We used six modelling approaches to assess cause-specific mortality, with the Cause of Death Ensemble Model (CODEm) generating estimates for most causes. We used a series of novel analyses to systematically quantify the drivers of trends in mortality across geographies. First, we assessed observed and expected levels and trends of cause-specific mortality as they relate to the Socio-demographic Index (SDI), a summary indicator derived from measures of income per capita, educational attainment, and fertility. Second, we examined factors affecting total mortality patterns through a series of counterfactual scenarios, testing the magnitude by which population growth, population age structures, and epidemiological changes contributed to shifts in mortality. Finally, we attributed changes in life expectancy to changes in cause of death. We documented each step of the GBD 2015 estimation processes, as well as data sources, in accordance with Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER).FINDINGS: Globally, life expectancy from birth increased from 61·7 years (95% uncertainty interval 61·4-61·9) in 1980 to 71·8 years (71·5-72·2) in 2015. Several countries in sub-Saharan Africa had very large gains in life expectancy from 2005 to 2015, rebounding from an era of exceedingly high loss of life due to HIV/AIDS. At the same time, many geographies saw life expectancy stagnate or decline, particularly for men and in countries with rising mortality from war or interpersonal violence. From 2005 to 2015, male life expectancy in Syria dropped by 11·3 years (3·7-17·4), to 62·6 years (56·5-70·2). Total deaths increased by 4·1% (2·6-5·6) from 2005 to 2015, rising to 55·8 million (54·9 million to 56·6 million) in 2015, but age-standardised death rates fell by 17·0% (15·8-18·1) during this time, underscoring changes in population growth and shifts in global age structures. The result was similar for non-communicable diseases (NCDs), with total deaths from these causes increasing by 14·1% (12·6-16·0) to 39·8 million (39·2 million to 40·5 million) in 2015, whereas age-standardised rates decreased by 13·1% (11·9-14·3). Globally, this mortality pattern emerged for several NCDs, including several types of cancer, ischaemic heart disease, cirrhosis, and Alzheimer's disease and other dementias. By contrast, both total deaths and age-standardised death rates due to communicable, maternal, neonatal, and nutritional conditions significantly declined from 2005 to 2015, gains largely attributable to decreases in mortality rates due to HIV/AIDS (42·1%, 39·1-44·6), malaria (43·1%, 34·7-51·8), neonatal preterm birth complications (29·8%, 24·8-34·9), and maternal disorders (29·1%, 19·3-37·1). Progress was slower for several causes, such as lower respiratory infections and nutritional deficiencies, whereas deaths increased for others, including dengue and drug use disorders. Age-standardised death rates due to injuries significantly declined from 2005 to 2015, yet interpersonal violence and war claimed increasingly more lives in some regions, particularly in the Middle East. In 2015, rotaviral enteritis (rotavirus) was the leading cause of under-5 deaths due to diarrhoea (146 000 deaths, 118 000-183 000) and pneumococcal pneumonia was the leading cause of under-5 deaths due to lower respiratory infections (393 000 deaths, 228 000-532 000), although pathogen-specific mortality varied by region. Globally, the effects of population growth, ageing, and changes in age-standardised death rates substantially differed by cause. Our analyses on the expected associations between cause-specific mortality and SDI show the regular shifts in cause of death composition and population age structure with rising SDI. Country patterns of premature mortality (measured as years of life lost [YLLs]) and how they differ from the level expected on the basis of SDI alone revealed distinct but highly heterogeneous patterns by region and country or territory. Ischaemic heart disease, stroke, and diabetes were among the leading causes of YLLs in most regions, but in many cases, intraregional results sharply diverged for ratios of observed and expected YLLs based on SDI. Communicable, maternal, neonatal, and nutritional diseases caused the most YLLs throughout sub-Saharan Africa, with observed YLLs far exceeding expected YLLs for countries in which malaria or HIV/AIDS remained the leading causes of early death.INTERPRETATION: At the global scale, age-specific mortality has steadily improved over the past 35 years; this pattern of general progress continued in the past decade. Progress has been faster in most countries than expected on the basis of development measured by the SDI. Against this background of progress, some countries have seen falls in life expectancy, and age-standardised death rates for some causes are increasing. Despite progress in reducing age-standardised death rates, population growth and ageing mean that the number of deaths from most non-communicable causes are increasing in most countries, putting increased demands on health systems.
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| 22. |
- Paice, J. A., et al.
(författare)
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A black hole X-ray binary at similar to 100 Hz : multiwavelength timing of MAXIJ1820+070 with HiPERCAM and NICER
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966 .- 1745-3925 .- 1745-3933. ; 490:1, s. L62-L66
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Tidskriftsartikel (refereegranskat)abstract
- We report on simultaneous sub-second optical and X-ray timing observations of the low-mass X-ray binary black hole candidate MAXI J1820+070. The bright 2018 outburst rise allowed simultaneous photometry in five optical bands (ugrizs) with HiPERCAM/GTC (Optical) at frame rates over 100 Hz, together with NICER/ISS observations (X-rays). Intense (factor of 2) red flaring activity in the optical is seen over a broad range of time-scales down to similar to 10 ms. Cross-correlating the bands reveals a prominent anticorrelation on time-scales of similar to seconds, and a narrow sub-second correlation at a lag of approximate to+165 ms (optical lagging X-rays). This lag increases with optical wavelength, and is approximately constant over Fourier frequencies of similar to 0.3-10 Hz. These features are consistent with an origin in the inner accretion flow and jet base within similar to 5000 Gravitational radii. An additional similar to+5 s lag feature may be ascribable to disc reprocessing. MAXI J1820+070 is the third black hole transient to display a clear similar to 0.1 s optical lag, which may be common feature in such objects. The sub-second lag variation with wavelength is novel, and may allow constraints on internal shock jet stratification models.
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| 23. |
- Paice, J. A., et al.
(författare)
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The evolution of rapid optical/X-ray timing correlations in the initial hard state of MAXIJ1820+070
- 2021
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 505:3, s. 3452-3469
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Tidskriftsartikel (refereegranskat)abstract
- We report on a multiepoch campaign of rapid optical/X-ray timing observations of the superbright 2018 outburst of MAXIJ1820+070, a black hole low-mass X-ray binary system. The observations spanned 80 d in the initial hard state and were taken with NTT/ULTRACAM and GTC/HiPERCAM in the optical (u(s)g(s)r(s)i(s)z(s) filters at time resolutions of 8-300Hz) and with ISS/NICER in X-rays. We find (i) a growing anticorrelation between the optical and X-ray light curves, (ii) a steady, positive correlation at an optical lag of similar to 0.2s (with a longer lag at longer wavelengths) present in all epochs, and (iii) a curious positive correlation at negative optical lags in the last, X-ray softest epoch, with longer wavelengths showing a greater correlation and a more negative lag. To explain these, we postulate the possible existence of two synchrotron-emitting components - a compact jet and a hot flow. In our model, the significance of the jet decreases over the outburst, while the hot flow remains static (thus, relatively, increasing in significance). We also discuss a previously discovered quasi-periodic oscillation and note how it creates coherent optical time lags, stronger at longer wavelengths, during at least two epochs.
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| 24. |
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| 25. |
- Fitzmaurice, C., et al.
(författare)
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Global, Regional, and National Cancer Incidence, Mortality, Years of Life Lost, Years Lived With Disability, and Disability-Adjusted Life-years for 32 Cancer Groups, 1990 to 2015. A Systematic Analysis for the Global Burden of Disease Study
- 2017
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Ingår i: Jama Oncology. - : American Medical Association (AMA). - 2374-2445 .- 2374-2437. ; 3:4, s. 524-548
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Cancer is the second leading cause of death worldwide. Current estimates on the burden of cancer are needed for cancer control planning. OBJECTIVE To estimate mortality, incidence, years lived with disability (YLDs), years of life lost (YLLs), and disability-adjusted life-years (DALYs) for 32 cancers in 195 countries and territories from 1990 to 2015. EVIDENCE REVIEW Cancer mortality was estimated using vital registration system data, cancer registry incidence data (transformed to mortality estimates using separately estimated mortality to incidence [MI] ratios), and verbal autopsy data. Cancer incidence was calculated by dividing mortality estimates through the modeled MI ratios. To calculate cancer prevalence, MI ratios were used to model survival. To calculate YLDs, prevalence estimates were multiplied by disability weights. The YLLs were estimated by multiplying age-specific cancer deaths by the reference life expectancy. DALYs were estimated as the sum of YLDs and YLLs. A sociodemographic index (SDI) was created for each location based on income per capita, educational attainment, and fertility. Countries were categorized by SDI quintiles to summarize results. FINDINGS In 2015, there were 17.5 million cancer cases worldwide and 8.7 million deaths. Between 2005 and 2015, cancer cases increased by 33%, with population aging contributing 16%, population growth 13%, and changes in age-specific rates contributing 4%. For men, the most common cancer globallywas prostate cancer (1.6 million cases). Tracheal, bronchus, and lung cancerwas the leading cause of cancer deaths and DALYs in men (1.2 million deaths and 25.9 million DALYs). For women, the most common cancerwas breast cancer (2.4 million cases). Breast cancerwas also the leading cause of cancer deaths and DALYs forwomen (523000 deaths and 15.1 million DALYs). Overall, cancer caused 208.3 million DALYs worldwide in 2015 for both sexes combined. Between 2005 and 2015, age-standardized incidence rates for all cancers combined increased in 174 of 195 countries or territories. Age-standardized death rates (ASDRs) for all cancers combined decreased within that timeframe in 140 of 195 countries or territories. Countries with an increase in the ASDR due to all cancers were largely located on the African continent. Of all cancers, deaths between 2005 and 2015 decreased significantly for Hodgkin lymphoma (-6.1%[95% uncertainty interval (UI), -10.6% to -1.3%]). The number of deaths also decreased for esophageal cancer, stomach cancer, and chronic myeloid leukemia, although these results were not statistically significant. CONCLUSION AND RELEVANCE As part of the epidemiological transition, cancer incidence is expected to increase in the future, further straining limited health care resources. Appropriate allocation of resources for cancer prevention, early diagnosis, and curative and palliative care requires detailed knowledge of the local burden of cancer. The GBD 2015 study results demonstrate that progress is possible in the war against cancer. However, the major findings also highlight an unmet need for cancer prevention efforts, including tobacco control, vaccination, and the promotion of physical activity and a healthy diet.
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| 26. |
- Kupfer, T., et al.
(författare)
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The OmegaWhite Survey for Short-period Variable Stars. V. Discovery of an Ultracompact Hot Subdwarf Binary with a Compact Companion in a 44-minute Orbit
- 2017
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 851:1
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of the ultracompact hot subdwarf (sdOB) binary OW J074106.0-294811.0 with an orbital period of P-orb = 44.66279 +/- 1.16 x 10(-4) minutes, making it the most compact hot subdwarf binary known. Spectroscopic observations using the VLT, Gemini and Keck telescopes revealed a He-sdOB primary with an intermediate helium abundance, T-eff = 39 400 +/- 500 K and log g = 5.74 +/- 0.09. High signal-to-noise ratio light curves show strong ellipsoidal modulation resulting in a derived sdOB mass M-sdOB= 0.23 +/- 0.12 M-circle dot with a WD companion (M-WD = 0.72 +/- 0.17 M-circle dot). The mass ratio was found to be q = M-sdOB/M-WD = 0.32 +/- 0.10. The derived mass for the He-sdOB is inconsistent with the canonical mass for hot subdwarfs of approximate to 0.47 M-circle dot. To put constraints on the structure and evolutionary history of the sdOB star we compared the derived T-eff, log g, and sdOB mass to evolutionary tracks of helium stars and helium white dwarfs calculated with Modules for Experiments in Stellar Astrophysics (MESA). We find that the best-fitting model is a helium white dwarf with a mass of 0.320 M-circle dot, which left the common envelope approximate to 1.1 Myr ago, which is consistent with the observations. As a helium white dwarf with a massive white dwarf companion, the object will reach contact in 17.6 Myr at an orbital period of 5 minutes. Depending on the spin-orbit synchronization timescale the object will either merge to form an R CrB star or end up as a stably accreting AM CVn-type system with a helium white dwarf donor.
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| 27. |
- Shahbaz, T., et al.
(författare)
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A rapid optical and X-ray timing study of the neutron star X-ray binary SwiftJ1858.6-0814
- 2023
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 520:1, s. 542-559
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Tidskriftsartikel (refereegranskat)abstract
- We present a rapid timing analysis of optical (HiPERCAM and ULTRACAM) and X-ray (NICER) observations of the X-ray transient SwiftJ1858.6-0814 during 2018 and 2019. The optical light curves show relatively slow, large amplitude (similar to 1mag in g(s)) 'blue' flares (i.e. stronger at shorter wavelengths) on time-scales of similar to minutes as well as fast, small amplitude (similar to 0.1mag in g(s)) 'red' flares (i.e. stronger at longer wavelengths) on time-scales of similar to seconds. The 'blue' and 'red' flares are consistent with X-ray reprocessing and optically thin synchrotron emission, respectively, similar to what is observed in other X-ray binaries. The simultaneous optical versus soft- and hard-band X-ray light curves show time- and energy-dependent correlations. The 2019 March 4 and parts of the June data show a nearly symmetric positive cross-correlations (CCFs) at positive lags consistent with simple X-ray disc reprocessing. The soft- and hard-band CCFs are similar and can be reproduced if disc reprocessing dominates in the optical and one component (disc or synchrotron Comptonization) dominates both the soft and hard X-rays. A part of the 2019 June data shows a very different CCFs. The observed positive correlation at negative lag in the soft band can be reproduced if the optical synchrotron emission is correlated with the hot flow X-ray emission. The observed timing properties are in qualitative agreement with the hybrid inner hot accretion flow model, where the relative role of the different X-ray and optical components that vary during the course of the outburst, as well as on shorter time-scales, govern the shape of the optical/X-ray CCFs.
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| 28. |
- Burdge, Kevin B., et al.
(författare)
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A 62-minute orbital period black widow binary in a wide hierarchical triple
- 2022
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 605:7908, s. 41-45
-
Tidskriftsartikel (refereegranskat)abstract
- Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original 'black widow', the eight-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20)(1), high-energy emission originating from the pulsar2 is irradiating and may eventually destroy(3) a low-mass companion. These systems are not only physical laboratories that reveal the interesting results of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars(4), allowing for robust tests of the neutron star equation of state. Here we report observations of ZTF J1406+1222, a wide hierarchical triple hosting a 62-minute orbital period black widow candidate, the optical flux of which varies by a factor of more than ten. ZTF J1406+1222 pushes the boundaries of evolutionary models(5), falling below the 80-minute minimum orbital period of hydrogen-rich systems. The wide tertiary companion is a rare low-metallicity cool subdwarf star, and the system has a Galactic halo orbit consistent with passing near the Galactic Centre, making it a probe of formation channels, neutron star kick physics(6) and binary evolution.
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| 29. |
- Buzzetti, Elena, et al.
(författare)
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Collagen proportionate area is an independent predictor of long-term outcome in patients with non-alcoholic fatty liver disease
- 2019
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Ingår i: Alimentary Pharmacology and Therapeutics. - : WILEY. - 0269-2813 .- 1365-2036. ; 49:9, s. 1214-1222
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Tidskriftsartikel (refereegranskat)abstract
- Background Collagen proportionate area (CPA) measurement is a technique that quantifies fibrous tissue in liver biopsies by measuring the amount of collagen deposition as a proportion of the total biopsy area. CPA predicts clinical outcomes in patients with HCV and can sub-classify cirrhosis. Aim To test the ability of CPA to quantify fibrosis and predict clinical outcomes in patients with NAFLD. Methods We assessed consecutive patients with biopsy-proven NAFLD from three European centres. Clinical and laboratory data were collected at baseline and at the time of the last clinical follow-up or death. CPA was performed at two different objective magnifications, whole biopsy macro and x4 objective magnification, named standard (SM) and high (HM) magnification respectively. The correlation between CPA and liver stiffness was assessed in a sub-group of patients. Results Of 437 patients, 32 (7.3%) decompensated and/or died from liver-related causes during a median follow-up of 103 months. CPA correlated with liver stiffness and liver fibrosis stage across the whole spectrum of fibrosis. HM CPA was significantly higher than SM CPA in stages F0-F3 but similar in cirrhosis, reflecting a higher ability to capture pericellular/perisinusoidal fibrosis at early stages. Age at baseline (HR: 1.04, 95% CI: 1.01-1.08), HM CPA (HR: 1.04 per 1% increase, 95% CI: 1.01-1.08) and presence of advanced fibrosis (HR: 15.4, 95% CI: 5.02-47.84) were independent predictors of liver-related clinical outcomes at standard and competing risk multivariate Cox-regression analysis. Conclusions CPA accurately measures fibrosis and is an independent predictor of clinical outcomes in NAFLD; hence it merits further evaluation as a surrogate endpoint in clinical trials.
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| 30. |
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| 31. |
- Dhillon, Shweta, et al.
(författare)
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Modelling capacity fade in silicon-graphite composite electrodes for lithium-ion batteries
- 2021
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Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 377
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Tidskriftsartikel (refereegranskat)abstract
- Silicon-based composite electrodes in lithium ion batteries attract increasing attention because of their high theoretical capacity. Here, numerical simulations are used to better understand the interplay between electrochemical and morphological behavior of the silicon-graphite (1:2.7) composite electrode during galvanostatic cycling. Finite element methodology is used to solve a one-dimensional model based on the porous electrode and concentrated solution theory. Porosity changes in the silicon electrode and solid electrolyte interphase layer growth are also included in the model. The simulation results show that at lower rates, the electrode with high initial porosity is being fully utilized before the lower cut-off potential is reached. When comparing the computational results with experimental observations, it can be seen that the main reason for capacity fade is the increase in tortuosity in the diffusion pathway of lithium ions due to cracking of the silicon composite electrode upon electrochemical cycling.
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| 32. |
- Kassebaum, Nicholas J., et al.
(författare)
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Global, regional, and national disability-adjusted life-years (DALYs) for 315 diseases and injuries and healthy life expectancy (HALE), 1990-2015 : a systematic analysis for the Global Burden of Disease Study 2015
- 2016
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 388:10053, s. 1603-1658
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Tidskriftsartikel (refereegranskat)abstract
- Background Healthy life expectancy (HALE) and disability-adjusted life-years (DALYs) provide summary measures of health across geographies and time that can inform assessments of epidemiological patterns and health system performance, help to prioritise investments in research and development, and monitor progress toward the Sustainable Development Goals (SDGs). We aimed to provide updated HALE and DALYs for geographies worldwide and evaluate how disease burden changes with development. Methods We used results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2015 (GBD 2015) for all-cause mortality, cause-specific mortality, and non-fatal disease burden to derive HALE and DALYs by sex for 195 countries and territories from 1990 to 2015. We calculated DALYs by summing years of life lost (YLLs) and years of life lived with disability (YLDs) for each geography, age group, sex, and year. We estimated HALE using the Sullivan method, which draws from age-specific death rates and YLDs per capita. We then assessed how observed levels of DALYs and HALE differed from expected trends calculated with the Socio-demographic Index (SDI), a composite indicator constructed from measures of income per capita, average years of schooling, and total fertility rate. Findings Total global DALYs remained largely unchanged from 1990 to 2015, with decreases in communicable, neonatal, maternal, and nutritional (Group 1) disease DALYs off set by increased DALYs due to non-communicable diseases (NCDs). Much of this epidemiological transition was caused by changes in population growth and ageing, but it was accelerated by widespread improvements in SDI that also correlated strongly with the increasing importance of NCDs. Both total DALYs and age-standardised DALY rates due to most Group 1 causes significantly decreased by 2015, and although total burden climbed for the majority of NCDs, age-standardised DALY rates due to NCDs declined. Nonetheless, age-standardised DALY rates due to several high-burden NCDs (including osteoarthritis, drug use disorders, depression, diabetes, congenital birth defects, and skin, oral, and sense organ diseases) either increased or remained unchanged, leading to increases in their relative ranking in many geographies. From 2005 to 2015, HALE at birth increased by an average of 2.9 years (95% uncertainty interval 2.9-3.0) for men and 3.5 years (3.4-3.7) for women, while HALE at age 65 years improved by 0.85 years (0.78-0.92) and 1.2 years (1.1-1.3), respectively. Rising SDI was associated with consistently higher HALE and a somewhat smaller proportion of life spent with functional health loss; however, rising SDI was related to increases in total disability. Many countries and territories in central America and eastern sub-Saharan Africa had increasingly lower rates of disease burden than expected given their SDI. At the same time, a subset of geographies recorded a growing gap between observed and expected levels of DALYs, a trend driven mainly by rising burden due to war, interpersonal violence, and various NCDs. Interpretation Health is improving globally, but this means more populations are spending more time with functional health loss, an absolute expansion of morbidity. The proportion of life spent in ill health decreases somewhat with increasing SDI, a relative compression of morbidity, which supports continued efforts to elevate personal income, improve education, and limit fertility. Our analysis of DALYs and HALE and their relationship to SDI represents a robust framework on which to benchmark geography-specific health performance and SDG progress. Country-specific drivers of disease burden, particularly for causes with higher-than-expected DALYs, should inform financial and research investments, prevention efforts, health policies, and health system improvement initiatives for all countries along the development continuum.
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| 33. |
- Lagging, Martin, 1965, et al.
(författare)
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IP-10 predicts viral response and therapeutic outcome in difficult-to-treat patients with HCV genotype 1 infection
- 2006
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Ingår i: Hepatology. - : Ovid Technologies (Wolters Kluwer Health). - 0270-9139 .- 1527-3350. ; 44:6, s. 1617-25
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Tidskriftsartikel (refereegranskat)abstract
- Plasma from 173 patients with HCV genotype 1 infection was analyzed for IP-10 levels prior to treatment with pegylated interferon-alpha-2a and ribavirin. Significantly lower IP-10 levels were observed in patients achieving a rapid viral response (RVR) (P < .0001), even in those with body mass index (BMI) > or = 25 kg/m2 (P = .004) and with baseline viral load > or = 2 million IU/mL (P = .001). Similarly, significantly lower IP-10 levels were observed in patients obtaining a sustained viral response (SVR) (P = .0002), including those having higher BMI (P < .05), higher viral load (P = .0005), and both higher BMI and viral load (P < .03). In multivariate logistic regression analyses, a low IP-10 value was independently predictive of both RVR and SVR. A baseline cutoff IP-10 value of 600 pg/mL yielded a negative predictive value (NPV) of 79% (19/24) for all genotype 1-infected patients, which was comparable with that observed using a reduction in HCV-RNA by at least 2 logs after 12 weeks of therapy (NPV 86%; 19/22); by combining the two, 30 of 38 patients (NPV 79%) potentially could have been spared unnecessary therapy. In patients having both higher BMI and viral load, cut-off levels of 150 and 600 pg/mL yielded a positive predictive value (PPV) of 71% and NPV of 100%, respectively. In conclusion, pretreatment IP-10 levels predict RVR and SVR in patients infected with HCV genotype 1, even in those with higher BMI and viral load. A substantial proportion of the latter patients may achieve SVR in spite of unfavorable baseline characteristics if their pretreatment IP-10 level is low. Thus, pretreatment IP-10 analysis may prove helpful in decision-making regarding pharmaceutical intervention.
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| 34. |
- Lagging, Martin, 1965, et al.
(författare)
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Randomized comparison of 12 or 24 weeks of peginterferon alpha-2a and ribavirin in chronic hepatitis C virus genotype 2/3 infection.
- 2008
-
Ingår i: Hepatology (Baltimore, Md.). - : Ovid Technologies (Wolters Kluwer Health). - 1527-3350 .- 0270-9139. ; 47:6, s. 1837-45
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Tidskriftsartikel (refereegranskat)abstract
- Previous trials investigating the efficacy of treatment durations shorter than the standard of 24 weeks for chronic hepatitis C virus (HCV) genotype 2/3 infections have yielded discordant results. The aims of this investigator-initiated phase III study were to compare the efficacy of 12 or 24 weeks of treatment and to identify patients suitable for short-term therapy. Three hundred eighty-two genotype 2/3-infected patients [intention-to-treat (ITT) population] at 31 centers in Denmark, Finland, Norway, and Sweden were randomized to 12 or 24 weeks of peginterferon alpha-2a (180 microg/week) plus ribavirin (800 mg/day). Twelve weeks of therapy was inferior to 24 weeks in the ITT population (sustained viral response [SVR] rates: 59% versus 78%, P < 0.0001) and in the subgroups of patients infected with genotype 2 (56% versus 82%, P = 0.006) or 3 (58% versus 78%, P = 0.0015). These differences were observed regardless of the fibrosis stage. Age and HCV-RNA levels on days 7 and 29 were independent predictors of SVR. Short-term treatment was useful in patients < 40 years old, especially if HCV-RNA was undetectable on day 29, and also in patients > or = 40 years old, provided that HCV-RNA was below 1000 IU/mL on day 7 in addition to being undetectable on day 29. If neither of these two criteria were met for patients > or = 40 years old, 24 weeks of therapy was superior (P < 0.0001). CONCLUSION: Peginterferon/ribavirin treatment for 12 weeks in HCV genotype 2/3 infection is overall inferior to 24 weeks of treatment but may be useful in some patients with a rapid initial clearance of virus.
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| 35. |
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| 36. |
- Larsson, Simon B., et al.
(författare)
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HBsAg quantification for identification of liver disease in chronic hepatitis B virus carriers
- 2014
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Ingår i: Liver International. - : Wiley. - 1478-3223. ; 34:7
-
Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: Quantification of hepatitis B surface antigen (HBsAg) has been proposed as a useful diagnostic marker for clinical staging (identification of inactive carrier state) and prognosis of chronic hepatitis B virus (HBV) infection. The aim of this study was to investigate the correlation between HBsAg levels in serum and histological liver damage in patients with chronic infection. Methods: HBsAg levels in serum (by Abbott Architect) were related to HBV DNA, ALT and histological score (n = 160) and covalently closed circular DNA (cccDNA) (n = 84). Results: HBsAg levels correlated with cccDNA, serum HBV DNA, ALT and high inflammation scores (P < 0.001). Among HBeAg-negative patients, an HBsAg level below 3.0 log(10) IU/ml identified minimal liver damage (normal ALT and mild inflammation) with a predictive value of 92% (alone) or 96% (in combination with HBV DNA <4.0 log(10) copies/ml), whereas an HBsAg level above 3.5 log(10) IU/ml identified severe inflammation with a predictive value of 16% (alone) or 33% (in combination with HBV DNA >5.0 log(10) copies/ml). Conclusions: HBsAg levels reflect clinical stage and liver disease, and a combined quantification of HBsAg and HBV DNA may improve clinical staging.
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| 37. |
- Lindh, Magnus, 1960, et al.
(författare)
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Core promoter mutations and genotypes in relation to viral replication and liver damage in East Asian hepatitis B virus carriers.
- 1999
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Ingår i: The Journal of infectious diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 179:4, s. 775-82
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Tidskriftsartikel (refereegranskat)abstract
- Virus load and liver damage, as measured by quantitative polymerase chain reaction and histology activity index, were related to genotype and core promoter mutations in 43 chronic hepatitis B virus (HBV) carriers of East Asian origin. T-1762 mutants were more frequent in genotype C strains and were associated with more inflammation (P=.0036) and fibrosis (P=.0088) of the liver but not with hepatitis B e antigen (HBeAg) status or virus load. Conversely, precore mutations were associated with less liver inflammation (P=. 08), which was linked to HBeAg negativity and lower viral replication. Carriers with genotype C were more often HBeAg positive (P=.03) with precore wild type strains and more-severe liver inflammation (P=.009) than were those with genotype B. These findings suggest that pathogenic differences between genotypes may exist and that the T-1762 mutation may be useful as a marker for progressive liver damage but seem to contradict that down-regulation of HBeAg production is the major effect of this mutation.
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| 38. |
- Opgenoorth, Hermann J., et al.
(författare)
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Day-side ionospheric conductivities at Mars
- 2010
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633 .- 1873-5088. ; 58:10, s. 1139-1151
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Tidskriftsartikel (refereegranskat)abstract
- We present estimates of the day-side ionospheric conductivities at Mars based on magnetic field measurements by Mars Global Surveyor (MGS) at altitudes down to similar to 100 km during aerobraking orbits early in the mission. At Mars, the so-called ionospheric dynamo region, where plasma/neutral collisions permit electric currents perpendicular to the magnetic field, lies between 100 and 250 km altitude. We find that the ionosphere is highly conductive in this region, as expected, with peak Pedersen and Hall conductivities of 0.1-1.5 S/m depending on the solar illumination and induced magnetospheric conditions. Furthermore, we find a consistent double peak pattern in the altitude profile of the day-side Pedersen conductivity, similar to that on Titan found by Rosenqvist et al. (2009). A high altitude peak, located between 180 and 200 km, is equivalent to the terrestrial peak in the lower F-layer. A second and typically much stronger layer of Pedersen conductivity is observed between 120 and 130 km, which is below the Hall conductivity peak at about 130-140 km. In this altitude region, MGS finds a sharp decrease in induced magnetic field strength at the inner magnetospheric boundary, while the day-side electron density is known to remain high as far down as 100 km. We find that such Titan-like behaviour of the Pedersen conductivity is only observed under regions of strongly draped magnetospheric field-lines, and negligible crustal magnetic anomalies below the spacecraft. Above regions of strong crustal magnetic anomalies, the Pedersen conductivity profile becomes more Earth-like with one strong Pedersen peak above the Hall conductivity peak. Here, both conductivities are 1-2 orders of magnitude smaller than the above only weakly magnetised crustal regions, depending on the strength of the crustal anomaly field at ionospheric altitudes. This nature of the Pedersen conductivity together with the structured distribution of crustal anomalies all over the planet should give rise to strong conductivity gradients around such anomalies. Day-side ionospheric conductivities on Mars (in regions away from the crustal magnetic anomalies) and Titan seem to behave in a very similar manner when horizontally draped magnetic field-lines partially magnetise a sunlit ionosphere. Therefore, it appears that a similar double peak structure of strong Pedersen conductivity could be a more general feature of non-magnetised bodies with ionised upper atmospheres, and thus should be expected to occur also at other non-magnetised terrestrial planets like Venus or other planetary bodies within the host planet magnetospheres.
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| 39. |
- Riepl, J., et al.
(författare)
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Field-resolved high-order nonlinearities in a free-running terahertz quantum cascade laser
- 2022
-
Ingår i: CLEO : Science and Innovations, S and I 2022 - Science and Innovations, S and I 2022. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- Two-dimensional terahertz strong-field spectroscopy reveals wave-mixing processes up to eighth order in a free-running quantum cascade laser, unravelling its sub-cycle gain dynamics and nonlinearities in a regime of negative absorption.
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| 40. |
- Riepl, J, et al.
(författare)
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Field-resolved high-order sub- cycle nonlinearities in a terahertz semiconductor laser
- 2021
-
Ingår i: Light, science & applications. - : Springer Science and Business Media LLC. - 2047-7538. ; 10:1, s. 246-246
-
Tidskriftsartikel (refereegranskat)abstract
- The exploitation of ultrafast electron dynamics in quantum cascade lasers (QCLs) holds enormous potential forintense, compact mode-locked terahertz (THz) sources, squeezed THz light, frequency mixers, and comb-basedmetrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operationalTHz QCLs. Here, we employ high-field THz pulses to perform the first ultrafast two-dimensional spectroscopy of afree-running THz QCL. Strong incoherent and coherent nonlinearities up to eight-wave mixing are detected belowand above the laser threshold. These data not only reveal extremely short gain recovery times of 2 ps at the laserthreshold, they also reflect the nonlinear polarization dynamics of the QCL laser transition for the first time, where wequantify the corresponding dephasing times between 0.9 and 1.5 ps with increasing bias currents. A density-matrixapproach reproducing the emergence of all nonlinearities and their ultrafast evolution, simultaneously, allows us tomap the coherently induced trajectory of the Bloch vector. The observed high-order multi-wave mixing nonlinearitiesbenefit from resonant enhancement in the absence of absorption losses and bear potential for a number of futureapplications, ranging from efficient intracavity frequency conversion, mode proliferation to passive mode locking.
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| 41. |
- Riepl, J., et al.
(författare)
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Sub-cycle high-order nonlinearities in a free-running terahertz semiconductor laser
- 2022
-
Ingår i: The International Conference on Ultrafast Phenomena (UP) 2022. - 9781557528209
-
Konferensbidrag (refereegranskat)abstract
- Field-resolved two-dimensional spectroscopy reveals the sub-cycle gain dynamics of a free-running terahertz quantum cascade laser and disentangles resonantly enhanced nonlinearities up to eight-wave mixing in a regime where gain replaces absorption.
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| 42. |
- Riepl, J., et al.
(författare)
-
Sub-cycle high-order nonlinearities in a terahertz quantum cascade laser
- 2022
-
Ingår i: IRMMW-THz 2022 - 47th International Conference on Infrared, Millimeter and Terahertz Waves. - 2162-2035 .- 2162-2027. - 9781728194271 ; 2022-August
-
Konferensbidrag (refereegranskat)abstract
- Ultrafast electron dynamics in quantum cascade lasers hold enormous potential for the implementation of intense, compact mode-locked terahertz sources, squeezed terahertz light, frequency mixers, and comb-based metrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operational terahertz quantum cascade lasers. Here we show the first field-resolved two-dimensional terahertz spectroscopy of a free-running quantum cascade laser, revealing its sub-cycle gain dynamics and disentangling resonantly enhanced high-order nonlinearities up to eight-wave mixing in a regime of negative absorption.
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| 43. |
- Romero, Ana, 1975, et al.
(författare)
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Interferon (IFN)-gamma-inducible protein-10: association with histological results, viral kinetics, and outcome during treatment with pegylated IFN-alpha 2a and ribavirin for chronic hepatitis C virus infection
- 2006
-
Ingår i: J Infect Dis. - 0022-1899. ; 194:7, s. 895-903
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We investigated associations between interferon (IFN)-gamma-inducible protein (IP)-10 and liver histological results, viral kinetic response, and treatment outcome in patients infected with hepatitis C virus (HCV) genotypes 1-4. METHODS: Plasma IP-10 was monitored before, during, and after treatment with pegylated IFN- alpha 2a and ribavirin in 265 HCV-infected patients. RESULTS: In univariate analyses, a low baseline IP-10 level was significantly associated with low baseline viral load, rapid viral response (RVR), a sustained viral response (SVR), body mass index <25 kg/m2, and less-pronounced fibrosis, inflammation, and steatosis (for HCV genotypes other than 3). When the results of the univariate analyses were included in multivariate analyses, a low plasma IP-10 level, low baseline viral load, and genotype 2 or 3 infection were independent predictors of an RVR and SVR. IP-10 levels decreased 6 weeks into treatment and remained low in patients with an SVR. By contrast, plasma levels of IP-10 rebounded in patients who had detectable HCV RNA after the completion of treatment. Using cutoff IP-10 levels of 150 and 600 pg/mL for predicting an SVR in patients infected with HCV genotype 1 yielded a specificity and sensitivity of 81% and 95%, respectively. CONCLUSION: Baseline IP-10 levels are predictive of the response to HCV treatment.
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| 44. |
- Shev, S, et al.
(författare)
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The importance of cofactors in the histologic progression of minimal and mild chronic hepatitis C
- 1997
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Ingår i: Liver. - 0106-9543. ; 17:5, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- A follow-up liver biopsy was done 9-16 years (mean 12 years) after initial biopsy in 20 untreated Swedish patients infected with hepatitis C (8 men, 12 women; mean age 30 years at initial biopsy) in whom first biopsy had been classified as chronic persistent hepatitis. A significant progression of liver damage was found when using Histology Activity Index (HAI) scoring according to Knodell (p=0.006 for total HAI score; p=0.03 for grading, i.e., sum of HAI components 1, 2, and 3; p=0.01 for staging, i.e., HAI component 4, fibrosis). Fourteen of 20 (70%) patients had increased while 6 had decreased or unchanged HAI scores on follow-up biopsy. Occasional heavy alcohol drinkers (n=6) had an increased follow-up HAI score as compared with nondrinkers (p<0.05). Eight of 14 who deteriorated on follow-up versus 0 of 6 with improved or unchanged liver histology were anti-HBc positive (p=0.04). There was no significant correlation between HCV genotype and prognosis; however, the only two patients with liver cirrhosis on follow-up had genotype 1b. In conclusion, most patients with minimal or mild chronic hepatitis C in the present study had histologic progression on the latest biopsy. Cofactors such as alcohol abuse and exposure to hepatitis B may have a greater influence than HCV alone in determining the rate of deterioration of liver disease.
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| 45. |
- Westin, Johan, 1965, et al.
(författare)
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A non-invasive fibrosis score predicts treatment outcome in chronic hepatitis C virus infection.
- 2008
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Ingår i: Scandinavian journal of gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 43:1, s. 73-80
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The results of a previous study suggest that an index calculated according to the formula (normalized ASAT x PK-INR) x 100/thrombocyte count (x 10(9)/L; GUCI) may reflect liver fibrosis in patients with chronic hepatitis C virus (HCV) infection. The aims of the present study were (i) to validate the association between the Göteborg University Cirrhosis Index (GUCI) score and liver fibrosis and (ii) to evaluate the utility of this index in predicting the outcome of antiviral treatment. MATERIAL AND METHODS: A total of 269 patients with chronic HCV infection, stratified according to HCV genotype (1/4 versus 2/3) participated in a phase III trial using pegylated interferon alpha-2a and ribavirin (DITTO study). Retrospective analyses of the baseline GUCI scores and assessments of pretreatment liver biopsies using the Ishak protocol were performed. Cut-off GUCI scores were calculated to distinguish patients with a high or low probability of sustained viral response (SVR). RESULTS: Striking associations between GUCI and Ishak fibrosis stages (stages 0-2 versus stages 3-4, p = 0.0002, stages 3-4 versus stages 5-6, p = 0.002) were observed. In patients with genotype 1 or 4, a GUCI score below 0.33 was associated with a rapid viral response to antiviral treatment and an SVR rate of 80%. Ninety-two percent of patients (92/101) with a SVR had a pretreatment GUCI score below 1.11. CONCLUSIONS: Our results suggest that the GUCI score appropriately reflects the stage of liver fibrosis in HCV-infected patients, and predicts initial viral kinetics as well as treatment outcome in patients infected with HCV genotype 1 or 4.
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| 46. |
- Westin, Johan, 1965, et al.
(författare)
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Are FoxP3(+) cells involved in hyporesponsiveness to interferon/ribavirin therapy in chronic hepatitis C?
- 2011
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Ingår i: Journal of viral hepatitis. - : Wiley. - 1365-2893 .- 1352-0504. ; 18:2, s. 149-151
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Tidskriftsartikel (refereegranskat)abstract
- Summary. We aimed to clarify the role of liver-infiltrating FoxP3(+)T cells for the response to therapy in chronic hepatitis C. Liver biopsies from 52 patients were collected prior to the start of interferon/ribavirin treatment, and the kinetics of viral decay during treatment were compared in patients with high and low infiltration of FoxP3(+) cells. These groups did not differ with respect to the effectiveness of early viral clearance or the frequency of sustained viral response. Our data imply that FoxP3(+) cell-mediated immunosuppression is not a major mechanism of hyporesponsiveness to interferon-based therapy in chronic hepatitis C.
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| 47. |
- Westin, Johan, 1965, et al.
(författare)
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Impact of hepatic steatosis on viral kinetics and treatment outcome during antiviral treatment of chronic HCV infection
- 2007
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Ingår i: J Viral Hepat. - : Wiley. - 1352-0504. ; 14:1, s. 29-35
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Tidskriftsartikel (refereegranskat)abstract
- Liver steatosis is highly prevalent in chronic hepatitis C virus (HCV) infection, especially in patients infected with genotype 3 virus, but its significance for the outcome of antiviral treatment is not fully understood. We have monitored steatosis in liver biopsies from 231 patients with chronic HCV infection who received pegylated recombinant interferon-alpha and ribavirin in a phase III study (DITTO trial). The degree of steatosis, along with relevant metabolic parameters, was correlated with the early disappearance of virus and with the final outcome of treatment. Our data suggest that the presence of steatosis impairs the early reduction of viral load during treatment in patients infected with HCV genotype 3 and non-3. Steatosis negatively affected the final outcome of treatment mainly in patients infected with HCV genotype non-3 virus. Based on these findings, we propose that interventions aiming at reducing hepatic steatosis prior to the onset of antiviral therapy may be of benefit to patients infected with HCV of the non-3 genotypes. Patients infected with genotype 3, on the other hand, should be offered early antiviral treatment.
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