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| 2. |
- Fulle, M., et al.
(författare)
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Evolution Of The Dust Size Distribution Of Comet 67P/Churyumov-Gerasimenko From 2.2 Au To Perihelion
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 821:1
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Tidskriftsartikel (refereegranskat)abstract
- The Rosetta probe, orbiting Jupiter-family comet 67P/Churyumov-Gerasimenko, has been detecting individual dust particles of mass larger than 10(-10) kg by means of the GIADA dust collector and the OSIRIS Wide Angle Camera and Narrow Angle Camera since 2014 August and will continue until 2016 September. Detections of single dust particles allow us to estimate the anisotropic dust flux from 67P, infer the dust loss rate and size distribution at the surface of the sunlit nucleus, and see whether the dust size distribution of 67P evolves in time. The velocity of the Rosetta orbiter, relative to 67P, is much lower than the dust velocity measured by GIADA, thus dust counts when GIADA is nadir-pointing will directly provide the dust flux. In OSIRIS observations, the dust flux is derived from the measurement of the dust space density close to the spacecraft. Under the assumption of radial expansion of the dust, observations in the nadir direction provide the distance of the particles by measuring their trail length, with a parallax baseline determined by the motion of the spacecraft. The dust size distribution at sizes > 1 mm observed by OSIRIS is consistent with a differential power index of -4, which was derived from models of 67P's trail. At sizes <1 mm, the size distribution observed by GIADA shows a strong time evolution, with a differential power index drifting from -2 beyond 2 au to -3.7 at perihelion, in agreement with the evolution derived from coma and tail models based on ground-based data. The refractory-to-water mass ratio of the nucleus is close to six during the entire inbound orbit and at perihelion.
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| 3. |
- Bryant, J. M., et al.
(författare)
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Emergence and spread of a human-transmissible multidrug-resistant nontuberculous mycobacterium
- 2016
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 354:6313, s. 751-757
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Tidskriftsartikel (refereegranskat)abstract
- Lung infections with Mycobacterium abscessus, a species of multidrug-resistant nontuberculous mycobacteria, are emerging as an important global threat to individuals with cystic fibrosis (CF), in whom M. abscessus accelerates inflammatory lung damage, leading to increased morbidity and mortality. Previously, M. abscessus was thought to be independently acquired by susceptible individuals from the environment. However, using whole-genome analysis of a global collection of clinical isolates, we show that the majority of M. abscessus infections are acquired through transmission, potentially via fomites and aerosols, of recently emerged dominant circulating clones that have spread globally. We demonstrate that these clones are associated with worse clinical outcomes, show increased virulence in cell-based and mouse infection models, and thus represent an urgent international infection challenge.
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| 7. |
- Rotundi, Alessandra, et al.
(författare)
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Dust measurements in the coma of comet 67P/Churyumov-Gerasimenko inbound to the Sun
- 2015
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 347:6220
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Tidskriftsartikel (refereegranskat)abstract
- Critical measurements for understanding accretion and the dust/gas ratio in the solar nebula, where planets were forming 4.5 billion years ago, are being obtained by the GIADA (Grain Impact Analyser and Dust Accumulator) experiment on the European Space Agency's Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko. Between 3.6 and 3.4 astronomical units inbound, GIADA and OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) detected 35 outflowing grains of mass 10(-10) to 10(-7) kilograms, and 48 grains of mass 10(-5) to 10(-2) kilograms, respectively. Combined with gas data from the MIRO (Microwave Instrument for the Rosetta Orbiter) and ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instruments, we find a dust/gas mass ratio of 4 +/- 2 averaged over the sunlit nucleus surface. A cloud of larger grains also encircles the nucleus in bound orbits from the previous perihelion. The largest orbiting clumps are meter-sized, confirming the dust/gas ratio of 3 inferred at perihelion from models of dust comae and trails.
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| 8. |
- Blösch, Günter, et al.
(författare)
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Twenty-three unsolved problems in hydrology (UPH) - a community perspective
- 2019
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Ingår i: Hydrological Sciences Journal. - : Informa UK Limited. - 0262-6667 .- 2150-3435. ; 64:10, s. 1141-1158
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Tidskriftsartikel (refereegranskat)abstract
- This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.
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| 9. |
- Lee, Byung-Boong, et al.
(författare)
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Venous hemodynamic changes in lower limb venous disease : the UIP consensus according to scientific evidence
- 2016
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Ingår i: International Journal of Angiology. - : Springer. - 0392-9590 .- 1827-1839. ; 35:3, s. 236-352
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Tidskriftsartikel (refereegranskat)abstract
- There are excellent guidelines for clinicians to manage venous diseases but few reviews to assess their hemodynamic background. Hemodynamic concepts that evolved in the past have largely remained unchallenged in recent decades, perhaps due to their often complicated nature and in part due to emergence of new diagnostic techniques. Duplex ultrasound scanning and other imaging techniques which evolved in the latter part of the 20th century have dominated investigation. They have greatly improved our understanding of the anatomical patterns of venous reflux and obstruction. However, they do not provide the physiological basis for understanding the hemodynamics of flow, pressure, compliance and resistance. Hemodynamic investigations appear to provide a better correlation with post-treatment clinical outcome and quality of life than ultrasound findings. There is a far better prospect for understanding the complete picture of the patient's disability and response to management by combining ultrasound with hemodynamic studies. Accordingly, at the instigation of Dr Angelo Scuderi, the Union Internationale de Phlebologie (UIP) executive board commissioned a large number of experts to assess all aspects of management for venous disease by evidence-based principles. These included experts from various member societies including the European Venous Forum (EVF), American Venous Forum (AVF), American College of Phlebology (ACP) and Cardiovascular Disease Educational and Research Trust (CDERT). Their aim was to confirm or dispel long-held hemodynamic principles and to provide a comprehensive review of venous hemodynamic concepts underlying the pathophysiology of lower limb venous disorders, their usefulness for investigating patients and the relevant hemodynamic changes associated with various forms of treatment. Chapter 1 is devoted to basic hemodynamic concepts and normal venous physiology. Chapter 2 presents the mechanism and magnitude of hemodynamic changes in acute deep vein thrombosis indicating their pathophysiological and clinical significance. Chapter 3 describes the hemodynamic changes that occur in different classes of chronic venous disease and their relation to the anatomic extent of disease in the macrocirculation and microcirculation. The next four chapters (Chapters 4-7) describe the hemodynamic changes resulting from treatment by compression using different materials, intermittent compression devices, pharmacological agents and finally surgical or endovenous ablation. Chapter 8 discusses the unique hemodynamic features associated with alternative treatment techniques used by the CHIVA and ASVAL. Chapter 9 describes the hemodynamic effects following treatment to relieve pelvic reflux and obstruction. Finally, Chapter 10 demonstrates that contrary to general belief there is a moderate to good correlation between certain hemodynamic measurements and clinical severity of chronic venous disease. The authors believe that this document will be a timely asset to both clinicians and researchers alike. It is directed towards surgeons and physicians who are anxious to incorporate the conclusions of research into their daily practice. It is also directed to postgraduate trainees, vascular technologists and bioengineers, particularly to help them understand the hemodynamic background to pathophysiology, investigations and treatment of patients with venous disorders. Hopefully it will be a platform for those who would like to embark on new research in the field of venous disease.
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| 10. |
- Milli, J., et al.
(författare)
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Discovery of a low-mass companion inside the debris ring surrounding the F5V star HD 206893
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 597
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Uncovering the ingredients and the architecture of planetary systems is a very active field of research that has fuelled many new theories on giant planet formation, migration, composition, and interaction with the circumstellar environment. We aim at discovering and studying new such systems, to further expand our knowledge of how low-mass companions form and evolve.Methods. We obtained high-contrast H-band images of the circumstellar environment of the F5V star HD 206893, known to host a debris disc never detected in scattered light. These observations are part of the SPHERE High Angular Resolution Debris Disc Survey (SHARDDS) using the InfraRed Dual-band Imager and Spectrograph (IRDIS) installed on VLT/SPHERE.Results. We report the detection of a source with a contrast of 3.6 × 10−5 in the H-band, orbiting at a projected separation of 270 milliarcsecond or 10 au, corresponding to a mass in the range 24 to 73MJup for an age of the system in the range 0.2 to 2 Gyr. The detection was confirmed ten months later with VLT/NaCo, ruling out a background object with no proper motion. A faint extended emission compatible with the disc scattered light signal is also observed.Conclusions. The detection of a low-mass companion inside a massive debris disc makes this system an analog of other young planetary systems such as β Pictoris, HR 8799 or HD 95086 and requires now further characterisation of both components to understand their interactions.
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