Impact-Generated Dust Clouds Surrounding the Galilean Moons

Tenuous dust clouds of Jupiter's Galilean moons Io, Europa, Ganymede and Callisto have been detected with the in-situ dust detector on board the Galileo spacecraft. The majority of the dust particles have been sensed at altitudes below five radii of these lunar-sized satellites. We identify the particles in the dust clouds surrounding the moons by their impact direction, impact velocity, and mass distribution. Average particle sizes are 0.5 to $\rm 1 \mu m$, just above the detector threshold, indicating a size distribution with decreasing numbers towards bigger particles. Our results imply that the particles have been kicked up by hypervelocity impacts of micrometeoroids onto the satellites' surfaces. The measured radial dust density profiles are consistent with predictions by dynamical modeling for satellite ejecta produced by interplanetary impactors (Krivov et al., PSS, 2003, 51, 251--269), assuming yield, mass and velocity distributions of the ejecta from laboratory measurements. The dust clouds of the three outer Galilean moons have very similar properties and are in good agreement with the model predictions for solid ice-silicate surfaces. The dust density in the vicinity of Io, however, is more than an order of magnitude lower than expected from theory. This may be due to a softer, fluffier surface of Io (volcanic deposits) as compared to the other moons. The log-log slope of the dust number density in the clouds vs. distance from the satellite center ranges between --1.6 and --2.8. Appreciable variations of number densities obtained from individual flybys with varying geometry, especially at Callisto, might be indicative of leading-trailing asymmetries of the clouds due to the motion of the moons with respect to the field of impactors.Comment: Icarus, in press, 46 pages, 16 figures, 5 table

A method for the detection of clouds using AVHRR infrared observations

A method is proposed for cloud detection over sea using a single infrared channel of a high spatial resolution satellite radiometer. The method combines a spatial coherence test and an absolute threshold test for the temperature field. The threshold for the second test is automatically determined by a histogram analysis of data which were preselected by the coherence test. The coherence test used differs from the classical standard deviation test in the way of the test value computation: the weight of the pixel to be investigated is increased. A simulation shows that under conditions of low cloud cover this makes the proposed coherence test more sensitive than the standard deviation test. When applied to real data the test was also found to be very sensitive compared with visible and IR threshold tests. Cloud cover obtained by the whole method is finally compared with that resulting from the visible and IR histogram analysis procedure of Phulpin et al. This comparison indicates a high reliability of the proposed method

Die Illusionen der Berlin-brandenburgischen Landesplanung

Die vergangenen 3 1/2 Jahre waren (zwar nicht nur, aber auch) in Berlin und Brandenburg „heiße Zeiten“ für Zukunftswerkstätten, Denkfabriken und Kongresse. Wenn man den – mit breiten Filzstiften oder beschwörenden Worten – zu Papier gebrachten Visionen und suggestiven Plänen glauben darf, ist die Berlin-brandenburgische Landesplanung auf dem Reißbrett längst Wirklichkeit: Autofreie Stadt, Polyzentralität, Entlastungsstädte, Regierungsviertel, Bodenfonds, Grünschneisen und Sicherung der Naturpotentiale. Freilich kümmert sich die tatsächliche Entwicklung wenig um wohlmeinende Ideenkonzepte oder Debatten im Feuilleton. Sie gehorcht ganz anderen Entwicklungsgesetzen: Demographie und Migration, Eigentumsverhältnisse und Mieten, öffentliche Finanzknappheit und Weltmarktkonkurrenz lauten ihre Parameter. Sprich: die Ideen auf dem Papier nehmen sich demgegenüber – ohne Umsetzung in Baurecht und Finanzentscheidungen – oft hilflos aus. Für einen jungfräulich-naiven Glauben an die Gestaltungsspielräume der Landesentwicklung ist kein Raum, wo enge regionalwirtschaftliche, rechtliche und politische Restriktionen den staatlichen Handlungsrahmen einengen. Die Frage lautet deshalb schlicht: Wie realistisch sind die Konzepte? Welche Chancen bestehen – ernsthaft geprüft – sie umzusetzen – selbst bei unterstellter „best practice“? Wie stark engen die nicht steuerbaren Restriktionen gutgemeinte Planungen ein? Auf den folgenden Seiten soll versucht werden, drei in der Planung beliebte Vorstellungen zu hinterfragen und anhand dieser drei Punkte die Illusionen der Landesplanung offenzulegen

Entanglement without nonlocality

We consider the characterization of entanglement from the perspective of a Heisenberg formalism. We derive an original two-party generalized separability criteria, and from this describe a novel physical understanding of entanglement. We find that entanglement may be considered as fundamentally a local effect, and therefore as a separable computational resource from nonlocality. We show how entanglement differs from correlation physically, and explore the implications of this new conception of entanglement for the notion of classicality. We find that this understanding of entanglement extends naturally to multipartite cases.Comment: 9 pages. Expanded introduction and sections on physical entanglement and localit

The evolution of plasticity of dauer larva developmental arrest in the nematode Caenorhabditis elegans.

Organisms can end up in unfavourable conditions and to survive this they have evolved various strategies. Some organisms, including nematodes, survive unfavourable conditions by undergoing developmental arrest. The model nematode Caenorhabditis elegans has a developmental choice between two larval forms, and it chooses to develop into the arrested dauer larva form in unfavourable conditions (specifically, a lack of food and high population density, indicated by the concentration of a pheromone). Wild C. elegans isolates vary extensively in their dauer larva arrest phenotypes, and this prompts the question of what selective pressures maintain such phenotypic diversity? To investigate this we grew C. elegans in four different environments, consisting of different combinations of cues that can induce dauer larva development: two combinations of food concentration (high and low) in the presence or absence of a dauer larva-inducing pheromone. Five generations of artificial selection of dauer larvae resulted in an overall increase in dauer larva formation in most selection regimes. The presence of pheromone in the environment selected for twice the number of dauer larvae, compared with environments not containing pheromone. Further, only a high food concentration environment containing pheromone increased the plasticity of dauer larva formation. These evolutionary responses also affected the timing of the worms' reproduction. Overall, these results give an insight into the environments that can select for different plasticities of C. elegans dauer larva arrest phenotypes, suggesting that different combinations of environmental cues can select for the diversity of phenotypically plastic responses seen in C. elegans.We would like to thank Henrique Teotonio for the gift of the G140.A population, Louise Hughes and Laura Weldon for technical help, two anonymous reviewers for their comments, and NERC for funding.This is the final published version of the article. It was originally published in Ecology and Evolution (Diaz SA, Viney M, Ecology and Evolution 2015, 5(6), 1343–1353, doi:10.1002/ece3.1436) http://dx.doi.org/10.1002/ece3.143

Changes to the national strategies, plans and guidelines for the treatment of hepatitis C in people who inject drugs between 2013 and 2016: a cross-sectional survey of 34 European countries

Background: Hepatitis C virus (HCV) infection is the leading cause of cirrhosis, end-stage liver disease and hepatocellular carcinoma (HCC) worldwide. In Europe, people who inject drugs (PWID) represent the majority of HCV infections, but are often excluded from treatment. The aim of this study was to report on national HCV strategies, action plans and guidelines in European countries that include HCV treatment for the general population as well as for PWID. Data on access to direct-acting antivirals (DAAs) were also collected. Methods: In 2016, 38 non-governmental organisations, universities and public health institutions that work with PWID in 34 European countries were invited to complete a 16-item online survey about current national HCV treatment policies and guidelines. Data from 2016 were compared to those from 2013 for 33 European countries, and time trends are presented. Differences in the data were analysed. Data from 2016 on general access to DAAs in PWID are presented separately. Results: The response rate was 100%. Fourteen countries (42%) reported having a national HCV strategy covering HCV treatment; 12 of these addressed HCV treatment for PWID. Respondents from ten countries (29%) reported having a national HCV action plan. PWID were specifically included in seven of them. Twenty-nine countries (85%) reported having national HCV treatment guidelines. PWID were specifically included in 23 (79%) of them. Compared to 2013, respondents reported that an additional seven countries (25%) had national strategies, an additional eight countries (29%) had action plans and an additional six countries (19%) had HCV treatment guidelines. However, PWID were not included in two, four and six of those countries, respectively. DAAs were reported to be available in 91% of the study countries, with restrictions reported in 71% of them. Conclusion: Respondents reported that fewer than half of the European countries in this study had a national HCV strategy and/or action plan, with even fewer including PWID. However, when compared to 2013, the number of such countries had slightly increased. Although PWID are often addressed in clinical guidelines, strategic action is needed to increase access to HCV treatment for this group and the situation should be regularly monitored