scholarly journals The role of ice lines in the formation of Uranus and Neptune

2020 ◽  
Vol 378 (2187) ◽  
pp. 20200107 ◽  
Author(s):  
O. Mousis ◽  
A. Aguichine ◽  
R. Helled ◽  
P. G. J. Irwin ◽  
J. I. Lunine
Keyword(s):  
Transport Model ◽  
Outer Region ◽  
Building Blocks ◽  
Planetary Formation ◽  
Physical Conditions ◽  
Elemental Abundances ◽  
Self Consistent ◽  
Protosolar Nebula ◽  
Do So

We aim at investigating whether the chemical composition of the outer region of the protosolar nebula can be consistent with current estimates of the elemental abundances in the ice giants. To do so, we use a self-consistent evolutionary disc and transport model to investigate the time and radial distributions of H 2 O, CO, CO 2 , CH 3 OH, CH 4 , N 2 and H 2 S, i.e. the main O-, C-, N and S-bearing volatiles in the outer disc. We show that it is impossible to accrete a mixture composed of gas and solids from the disc with a C/H ratio presenting enrichments comparable to the measurements (approx. 70 times protosolar). We also find that the C/N and C/S ratios measured in Uranus and Neptune are compatible with those acquired by building blocks agglomerated from solids condensed in the 10–20 AU region of the protosolar nebula. By contrast, the presence of protosolar C/N and C/S ratios in Uranus and Neptune would imply that their building blocks agglomerated from particles condensed at larger heliocentric distances. Our study outlines the importance of measuring the elemental abundances in the ice giant atmospheres, as they can be used to trace the planetary formation location, the origin of their building blocks and/or the chemical and physical conditions of the protosolar nebula. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

Ice lines and the formation of Uranus and Neptune

2020 ◽  
Author(s):  
Olivier Mousis ◽  
Artyom Aguichine ◽  
Ravit Helled ◽  
Patrick Irwin ◽  
Jonathan I. Lunine
Keyword(s):  
Chemical Composition ◽  
Transport Model ◽  
Outer Region ◽  
Building Blocks ◽  
Planetary Formation ◽  
Physical Conditions ◽  
Elemental Abundances ◽  
Self Consistent ◽  
Protosolar Nebula ◽  
Do So

<p>We aim at investigating whether the chemical composition of the outer region of the protosolar nebula can be consistent with current estimates of the elemental abundances in the ice giants. To do so, we use a self-consistent evolutionary disc and transport model to investigate the time and radial distributions of H<sub>2</sub>O, CO, N<sub>2</sub>, and H<sub>2</sub>S, i.e., the main O-, C-, N, and S-bearing volatiles in the outer disc. We show that it is impossible to accrete a mixture composed of gas and solids from the disc with a C/H ratio presenting enrichments comparable to the measurements (70 times protosolar). We also find that the C/N and C/S ratios measured in Uranus and Neptune are compatible with those acquired by building blocks agglomerated from grains and pebbles condensed in the vicinities of N<sub>2</sub> and CO ice lines in the nebula. In contrast, the presence of protosolar C/N and C/S ratios in Uranus and Neptune would imply that their building blocks agglomerated from particles condensed at higher heliocentric distances. Our study demonstrates the importance of measuring the elemental abundances in the ice giant atmospheres, as they can be used to trace the planetary formation location and/or the chemical and physical conditions of the protosolar nebula.<span class="Apple-converted-space"> </span></p>

scholarly journals Distribution of Kolmogorov-Sinaï Entropy in Self-Consistent Models of Barred Galaxies

1999 ◽  
Vol 172 ◽  
pp. 149-158
Author(s):  
H. Wozniak ◽  
D. Pfenniger
Keyword(s):  
Star Formation ◽  
Building Blocks ◽  
Maximum Extension ◽  
Star Forming ◽  
Barred Galaxies ◽  
Chaotic Orbits ◽  
Self Consistent ◽  
Elementary Building

AbstractThe properties of chaos in 2D self-consistent models of barred galaxies are investigated using Kolmogorov-Sinai entropy hKS. These models are constructed with Schwarzschild’s method which combines orbits as elementary building blocks.Most models are dominated by chaos near the 2/3 of the length of the bar and close to corotation. These locations correspond to regions where star-forming HII regions are observed because gas clouds could shock, shrink and fragment such that star formation could be ignited.The model the most similar to N-body models shows a peak of hKS between the corners of the rectangular-like x1 orbits and the maximum extension points of the Lagrangian orbits. This emphasizes the role of Lagrangian orbits in the morphology of bars. Most models essentially contain ‘semi-chaotic’ orbits confined inside the corotation.

Influence of Magnetic Fields on Solar Hydrodynamics: Experimental Results

1977 ◽  
Vol 36 ◽  
pp. 143-180 ◽  
Author(s):  
J.O. Stenflo
Keyword(s):  
Solar Activity ◽  
Energy Balance ◽  
Magnetic Fields ◽  
Solar Atmosphere ◽  
General Problem ◽  
Solar Rotation ◽  
Active Regions ◽  
Physical Conditions ◽  
Dynamic Phenomena

It is well-known that solar activity is basically caused by the Interaction of magnetic fields with convection and solar rotation, resulting in a great variety of dynamic phenomena, like flares, surges, sunspots, prominences, etc. Many conferences have been devoted to solar activity, including the role of magnetic fields. Similar attention has not been paid to the role of magnetic fields for the overall dynamics and energy balance of the solar atmosphere, related to the general problem of chromospheric and coronal heating. To penetrate this problem we have to focus our attention more on the physical conditions in the ‘quiet’ regions than on the conspicuous phenomena in active regions.

A Re-Appraisal of the Role of Blood Coagulation and Platelets in the Generalized Shwartzman Phenomenon

1966 ◽  
Vol 15 (03/04) ◽  
pp. 519-538 ◽  
Author(s):  
J Levin ◽  
E Beck
Keyword(s):  
Blood Coagulation ◽  
The State ◽  
Coagulation System ◽  
Renal Lesions ◽  
Intravascular Coagulation ◽  
Renal Glomeruli ◽  
Coagulation Mechanism ◽  
Shwartzman Phenomenon ◽  
Do So

SummaryThe role of intravascular coagulation in the production of the generalized Shwartzman phenomenon has been evaluated. The administration of endotoxin to animals prepared with Thorotrast results in activation of the coagulation mechanism with the resultant deposition of fibrinoid material in the renal glomeruli. Anticoagulation prevents alterations in the state of the coagulation system and inhibits development of the renal lesions. Platelets are not primarily involved. Platelet antiserum produces similar lesions in animals prepared with Thorotrast, but appears to do so in a manner which does not significantly involve intravascular coagulation.The production of adrenal cortical hemorrhage, comparable to that seen in the Waterhouse-Friderichsen syndrome, following the administration of endotoxin to animals that had previously received ACTH does not require intravascular coagulation and may not be a manifestation of the generalized Shwartzman phenomenon.

‘Wheels have been set in motion’: Geocentrism and Relativity in Tom Stoppard’s Rosencrantz and Guildenstern Are Dead

2018 ◽  
Author(s):  
Liliane Campos
Keyword(s):  
20Th Century ◽  
Film Adaptation ◽  
Frames Of Reference ◽  
Quantum Uncertainty ◽  
Galilean Relativity ◽  
Modern Physics ◽  
20Th Century Physics ◽  
Time Specific ◽  
Do So

By decentring our reading of Hamlet, Stoppard’s tragicomedy questions the legitimacy of centres and of stable frames of reference. So Liliane Campos examines how Stoppard plays with the physical and cosmological models he finds in Hamlet, particularly those of the wheel and the compass, and gives a new scientific depth to the fear that time is ‘out of joint’. In both his play and his own film adaptation, Stoppard’s rewriting gives a 20th-century twist to these metaphors, through references to relativity, indeterminacy, and the role of the observer. When they refer to the uncontrollable wheels of their fate, his characters no longer describe the destruction of order, but uncertainty about which order is at work, whether heliocentric or geocentric, random or tragic. When they express their loss of bearings, they do so through the thought experiments of modern physics, from Galilean relativity to quantum uncertainty, drawing our attention to shifting frames of reference. Much like Schrödinger’s cat, Stoppard’s Rosencrantz and Guildenstern are both dead and alive. As we observe their predicament, Campos argues, we are placed in the paradoxical position of the observer in 20th-century physics, and constantly reminded that our time-specific relation to the canon inevitably determines our interpretation.

Preparing the Child for Productive Life

IJOHMN ◽  
2019 ◽  
Vol 5 (4) ◽  
pp. 16
Author(s):  
Stella Baindu Fortune Fortune
Keyword(s):  
Learner Control ◽  
Counseling Services ◽  
Guidance And Counseling ◽  
School Life ◽  
Productive Life ◽  
Know How ◽  
Physical Conditions ◽  
The Family ◽  
Genetic Endowment

The nature of children’s development is greatly influenced by the environmental conditions in which they are brought up. The amount of social stimulation which they receive is of particular importance, and even if physical conditions are adequate, an unstimulating environment which provides with little opportunity or need to experiment or solve problems will result in low level of achievement. Perhaps the most important aspect of the child’s social development is beyond the reach of the teacher. For the first very important aspect of the child’s development lies in the home. Genetic endowment and cultural level of the family, coupled with the actual physical conditions of the home will have decisive effect on the child’s development and will continue to influence him throughout his school life. These factors are inaccessible to be influenced by the teacher but it is as well for him to have them in mind in his dealings with pupils. In addition, he will need to know how he may most effectively change his pupils along the lives he considers to be the most appropriate. That is, he will seek out the most efficient ways of getting pupils learn for productive life in future. The topic under review will be approached from various fronts which include; The Sociological and Philosophical models; role of the school; Learners’ responsibility; role of the teacher; discipline and learner control; role of the parent; guidance and counseling services and conclusion.

A First Principles Approach for Partitioning Linear Response Properties into Additive and Cooperative Contributions

2018 ◽  
Author(s):  
Daniel Lambrecht ◽  
Eric Berquist
Keyword(s):  
First Principles ◽  
Linear Response ◽  
Building Blocks ◽  
Field Method ◽  
Response Property ◽  
Response Properties ◽  
Consistent Field ◽  
Molecular Building Blocks ◽  
Self Consistent ◽  
Self Consistent Field

We present a first principles approach for decomposing molecular linear response properties into orthogonal (additive) plus non-orthogonal/cooperative contributions. This approach enables one to 1) identify the contributions of molecular building blocks like functional groups or monomer units to a given response property and 2) quantify cooperativity between these contributions. In analogy to the self consistent field method for molecular interactions, SCF(MI), we term our approach LR(MI). The theory, implementation and pilot data are described in detail in the manuscript and supporting information.

Helping when desire is low: The role of Expectancy in helping

2020 ◽  
Author(s):  
Małgorzata Kossowska
Keyword(s):  
Experimental Studies ◽  
Helping Behavior ◽  
Perceived Effectiveness ◽  
Do So

One might assume that the desire to help (here described as Want) is the essential driver of helping declarations and/or behaviors. However, even if desire to help is low, helping behavior may still occur if the expectancy regarding the perceived effectiveness of helping is high. We tested these predictions in a set of three experimental studies. In all three, we measured the desire to help (Want) and the Expectancy that the aid would be impactful for the victim; in addition, we manipulated Expectancy in Study 3. In Studies 1 and 3, we measured the participants’ declaration to help while in Study 2, their helping behavior was examined. In all three studies, we used variations of the same story about a victim. The results supported our hypothesis. Thus, the studies help to tease apart the determinants of helping behavior under conditions of lowered desire to do so, an issue of great importance in public policymaking.

History and Transport Policy

Transfers ◽  
2014 ◽  
Vol 4 (1) ◽  
pp. 45-62 ◽  
Author(s):  
Ueli Haefeli ◽  
Fritz Kobi ◽  
Ulrich Seewer
Keyword(s):  
Knowledge Transfer ◽  
Transport Policy ◽  
Science And Policy ◽  
Direct Knowledge ◽  
Academic System ◽  
Decision Making Processes ◽  
Policy And Planning ◽  
Policy Solutions ◽  
Do So

Based on analysis of two case studies in the Canton of Bern, this article examines the question of knowledge transfer from history to transport policy and planning in the recent past in Switzerland. It shows that for several reasons, direct knowledge transfer did not occur. In particular, historians have seldom become actively involved in transport planning and policy discourses, probably partly because the academic system offers no incentive to do so. However, historical knowledge has certainly influenced decision-making processes indirectly, via personal reflection of the actors in the world of practice or through Switzerland's strongly developed modes of political participation. Because the potential for knowledge transfer to contribute to better policy solutions has not been fully utilized, we recommend strengthening the role of existing interfaces between science and policy.

Stative Morpheme In Shimakonde, An Anticausative Morpheme?

2017 ◽  
Vol 19 ◽  
pp. 343-376
Author(s):  
Ronaldo Rodrigues De Paula
Keyword(s):  
External Argument ◽  
Bantu Language ◽  
Northern Regions ◽  
Do So

Tis paper aims to describe the syntax of the constructions that present the verbal extensions {-ik-} and {-uk-} and their allomorphs in Shimakonde, a Bantu language classifed as P23 in the Guthrie classifcation (GUTHRIE 1967-71). Tis language is spoken in the northern regions of Mozambique and Tanzania. Tese verbal extensions are reported in literature under the labels of stative, impositive, pseudo-passive, neuter, and quasi-passive (DOKE, 1947; SATYO, 1985; MCHOMBO, 1993; DUBINSKY SIMANGO, 1996; BENTLEY KULEMEKA, 2001; LIPHOLA, 2001; NGUNGA, 2004; KHUMALO, 2009; LEACH, 2010; LANGA, 2013). Te addition of the {-ik-} or {-uk-} morphemes to the verb structure usually demotes or suppresses the external argument, turning a basically transitive predicate into an intransitive one. Tis paper aims to investigate in Shimakonde if alternations from a dyadic to a monadic predicate, through the use of one of the aforementioned morphemes, are instances of the phenomenon known in literature as causative/ anticausative alternation (HASPELMATH, 1987, 1993; LEVIN RAPPAPORT HOVAV, 1992, 1995; NAVES, 1998, 2005; VAN HOUT, 2004; OLIVEIRA, 2011; KALLULLI, 2007). In order to do so, I analyze the grammatical role of this morpheme with two Shimakonde native consultants from different Mozambique districts (Mocimboa da Praia and Montepuez). Te feldwork activities consisted of translations of sentences from Portuguese to Shimakonde, testing the grammaticality of the proposed sentences. In order to examine the data that were collected, I adopted the Alexiadou, Anagnostopoulou and Schäfer (2006) refnement of the verbal categories by Levin Rappaport Hovav (1992, 1995). One of the results obtained is that the verbal extensions display an atelic reading (giving rise to stative interpretation) or a telic reading (giving rise to anticausative or passive interpretation). To account for the different interpretations in these constructions, I propose distinct associations between Asp head and Voice head in accordance with Kratzer (1996), Pylkkänen (2002), van Hout (2004), and Oliveira (2010).

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