Planet population synthesis driven by pebble accretion in cluster environments

The evolution of protoplanetary discs embedded in stellar clusters depends on the age and the stellar density in which they are embedded. Stellar clusters of young age and high stellar surface density destroy protoplanetary discs by external photoevaporation and stellar encounters. Here we consider the effect of background heating from newly formed stellar clusters on the structure of protoplanetary discs and how it affects the formation of planets in these discs. Our planet formation model is build on the core accretion scenario including pebble accretion. We synthesize planet populations that we compare to observations. The giant planets in our simulations migrate over large distances due to the fast type-II migration regime induced by a high disc viscosity ($\alpha=5.4 \times 10^{-3}$). Cold Jupiters (r>1 AU) originate preferably from the outer disc, while hot Jupiters (r<0.1 AU) preferably form in the inner disc. We find that the formation of gas giants via pebble accretion is in agreement with the metallicity correlation, meaning that more gas giants are formed at larger metallicity. However, our synthetic population of isolated stars host a significant amount of giant planets even at low metallicity, in contradiction to observations where giant planets are preferably found around high metallicity stars, indicating that pebble accretion is very efficient in the standard pebble accretion framework. On the other hand, discs around stars embedded in cluster environments hardly form any giant planets at low metallicity in agreement with observations, where these changes originate from the increased temperature in the outer parts of the disc, which prolongs the core accretion time-scale of the planet. We therefore conclude that the outer disc structure and the planet's formation location determines the giant planet occurrence rate and the formation efficiency of cold and hot Jupiters.Comment: 12 pages, accepted for publication in MNRA

Some applications of graph theory to finite groups

AbstractResults on vertex coloring and the vertex independence number of a finite graph are used to prove:Theorem. Let G be a finite group with conjugacy classes indexed by cardinality: 1 = |[x1]| ⩽|[x2]| ⩽···, and let CG(x) denote the centralizer of x. If m is the smallest integer i such that |[x1]|+|[x2]|+···+|[x1]|⩾|C(x1)|, then each abelian subgroup A of G has card inality|A|⩽ |[x1]|+|[x2]|+···+|[xm]|.Theorem. Let G be a finite group with a proper subgroup M, suchthat x∈M−{1}⇒CG(x)⊆ M. Then G contains at least [|G|13] pairwise non-commuting elements, and hence G cannot be covered by the union of fewer than [|G|13] abelian subgroups.Theorem. Let S be a locally maximal sum-free subset of the abelian group G. Then |S−S|+|SU−S|−3⩽|G|(1−|S−S|-1), with equality if and only if S−S is a subgroup H of G, [G:H]=3, and S is a coset of H.Some open problems are also stated

Aerodynamic characteristics of low-aspect-ratio wings at high supersonic Mach numbers

This paper presents some recently obtained data on the aerodynamic characteristics of low-aspect-ratio wings at supersonic Mach numbers of 4.04 and 6.9 and discusses some new methods of predicting the lift and drag of such wings. Data on lifting wings in the Mach number range above 2.5 are not plentiful and most of the available data may be found in NACA RM L51D17, NACA RM L51D30, NACA RM L52D15a, NACA RM L52K19, NACA RM L53D03, and NACA RM L53D30

Contribution to the chemistry of oils and fats with particular reference to butter fat

Experiments in animal nutrition have constituted a prominent line of investigation at the Massachusetts Experiment Station ever since its organisation, but not until 1890 was any attempt made by this station to ascertain the effect of feed on the composition of butter fat

The RNA-binding protein hnRNPLL induces a T cell alternative splicing program delineated by differential intron retention in polyadenylated RNA

BACKGROUND Retention of a subset of introns in spliced polyadenylated mRNA is emerging as a frequent, unexplained finding from RNA deep sequencing in mammalian cells. RESULTS Here we analyze intron retention in T lymphocytes by deep sequencing polyadenylated RNA. We show a developmentally regulated RNA-binding protein, hnRNPLL, induces retention of specific introns by sequencing RNA from T cells with an inactivating Hnrpll mutation and from B lymphocytes that physiologically downregulate Hnrpll during their differentiation. In Ptprc mRNA encoding the tyrosine phosphatase CD45, hnRNPLL induces selective retention of introns flanking exons 4 to 6; these correspond to the cassette exons containing hnRNPLL binding sites that are skipped in cells with normal, but not mutant or low, hnRNPLL. We identify similar patterns of hnRNPLL-induced differential intron retention flanking alternative exons in 14 other genes, representing novel elements of the hnRNPLL-induced splicing program in T cells. Retroviral expression of a normally spliced cDNA for one of these targets, Senp2, partially corrects the survival defect of Hnrpll-mutant T cells. We find that integrating a number of computational methods to detect genes with differentially retained introns provides a strategy to enrich for alternatively spliced exons in mammalian RNA-seq data, when complemented by RNA-seq analysis of purified cells with experimentally perturbed RNA-binding proteins. CONCLUSIONS Our findings demonstrate that intron retention in mRNA is induced by specific RNA-binding proteins and suggest a biological significance for this process in marking exons that are poised for alternative splicing.This work has been supported by grants from the National Health and Medical Research Council (Australia), the Wellcome Trust, the National Institutes of Health (USA) and the Biomedical Research Council (BMRC) of the Agency for Science, Technology and Research (A*STAR), Singapore

Romance tragedy of 'Romeo and Juliet' Style: A study in Qualitative Research with special focus on India and Nepal in the time period 1993-2013

This study presents romance tragedy of Romeo and Juliet style as a phenomenon that can be found in many cultures with recorded history. In spite of the illegality of lethal violence toward lovers in western countries and in spite of the adoption of a democratic constitution in India in 1950, stories of the public murder of dedicated lovers, especially in Northern India, began coming to worldwide attention in the media only since 1993. Through personal contacts in India and Nepal, real life stories of gross personal and community tragedy involving mainly the Hindu and Muslim religions have been collected. These stories are examined looking for a path of progress in terms of reconciliation and acceptance

Towards a Study of Potentially Tragic Romantic Events of Romeo and Juliet Style (Happening in the World Today and Mythological):

Incidents reported in the media have led to the choice of 'potentially tragic romantic events' as a topic for personal research. One such report was in the Guardian Weekly some time ago and involved an Indian man who hanged his son in public view for proceeding with a liaison that offended the family in their cultural setting. Another incident was the killing by sniper fire of a couple attempting to leave the city during the Balkan wars. The bridge where this happened is now called the Romeo and Juliet bridge. My background is in medicine, having graduated from the University of Adelaide in 1960, and later specialising in pathology and sexual health medicine. Coronial autopsy work has made me aware of youth suicide, and there is a story within my own family of one of my uncles committing suicide as a young man because he was not allowed to marry the girl of his choice. Voluntary pathology work has taken me to Nepal and my first visit was shortly after the royal massacre in 2001 where it is reputed that Crown Prince Diprendra, heir to the monarchy, killed his family having been forbidden by his mother to marry the girl of his choice. However, also from Nepal is the story of a couple who now enjoy good relationships with the woman's parents although at the time she had to elope and it took two years and the birth of a child before reconciliation was realised. In this study an attempt will be made to document and critically analyse stories, events and responses made by people involved, and to look for grounded theory pertinent to the responses of people and communities involved