1,703 research outputs found
Effect of Reaction & Convective Mixing on the Progenitor Mass of ONe White Dwarfs
Stars in the mass range ~8 - 12 are the most numerous massive
stars. This mass range is critical because it may lead to supernova (SN)
explosion, so it is important for the production of heavy elements and the
chemical evolution of the galaxy. We investigate the critical transition mass
(), which is the minimum initial stellar mass that attains the
conditions for hydrostatic carbon burning. Stars of masses < evolve to
the Asymptotic Giant Branch and then develop CO White Dwarfs, while stars of
masses ignite carbon in a partially degenerate CO core
and form electron degenerate ONe cores. These stars evolve to the Super AGB
(SAGB) phase and either become progenitors of ONe White Dwarfs or eventually
explode as electron-capture SN (EC-SN). We study the sensitivity of to
the C-burning reaction rate and to the treatment of convective mixing. In
particular, we show the effect of a recent determination of the
fusion rate, as well as the extension of the convective core during
hydrogen and helium burning on in solar metallicity stars. We choose
the 9 model to show the detailed characteristics of the evolution
with the new C-burning rate.Comment: Submitted to AIP Conference proceedings of Carpathian Summer School
of Physics-201
Competitive intelligence and its effect on UK banking strategy
EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Synthesis of C-rich dust in CO nova ourbursts
Context. Classical novae are thermonuclear explosions that take place in the
envelopes of accreting white dwarfs in stellar binary systems. The material
transferred onto the white dwarf piles up under degenerate conditions, driving
a thermonuclear runaway. In those outbursts, about 10-7 - 10-3 Msun, enriched
in CNO and, sometimes, other intermediate-mass elements (e.g., Ne, Na, Mg, or
Al, for ONe novae) are ejected into the interstellar medium. The large
concentrations of metals spectroscopically inferred in the nova ejecta reveal
that the (solar-like) material transferred from the secondary mixes with the
outermost layers of the underlying white dwarf.
Aims. Most theoretical models of nova outbursts reported to date yield, on
average, outflows characterized by O > C, from which only oxidized condensates
(e.g, O-rich grains) would be expected, in principle.
Methods. To specifically address whether CO novae can actually produce C-rich
dust, six different hydrodynamic nova models have been evolved, from accretion
to the expansion and ejection stages, with different choices for the
composition of the substrate with which the solar-like accreted material mixes.
Updated chemical profiles inside the H-exhausted core have been used, based on
stellar evolution calculations for a progenitor of 8 Msun through H and
He-burning phases.
Results. We show that these profiles lead to C-rich ejecta after the nova
outburst. This extends the possible contribution of novae to the inventory of
presolar grains identified in meteorites, particularly in a number of
carbonaceous phases (i.e., nanodiamonds, silicon carbides and graphites).Comment: 5 pages, accepted for publication in Astronomy & Astrophysic
The Paved Treasures in the Events of al-Shuf
Este artĂculo presenta a un sacerdote griego catĂłlico, historiador de
LĂbano, Hanania al-Munayyir (1756-1823) y su obra al-Durr al-Marsuf fi
Hawadith al-Shuf. Al-Munayyir serĂĄ analizado como cronĂłgrafo seguidor de la
secuencia anual de eventos, como un neocronĂłgrafo que interpreta y ofrece
su opiniĂłn, asĂ como un historiador metĂłdico cuyo enfoque analĂtico,
versatilidad y comprensiĂłn de la historia de LĂbano en su contexto local,
regional e internacional refleja la historia del cristianismo de Bilad al-Sham
escrita en el s. XVIII. Al-Munayyir fue capaz de liberarse de los lĂmites de su
comunidad religiosa y observar a LĂbano como una entidad Ășnica, pero frĂĄgil,
continuamente vulnerable por causa de las luchas internas y las
interferencias externas en sus asuntos.This article introduces a Greek Catholic priest, a historian from
Lebanon, Hanania al-Munayyir (1756-1823) and his book al-Durr al-Marsuf fi
Hawadith al-Shuf (The paved Treasures in the Events of al-Shuf). Al-Munayyir
will be discussed as a chronicler who followed the yearly sequence in relating
the events, as a neo chronicler who interpreted and gave his opinion, and as
an analytical historian whose thematic approach, versatility, and
understanding of the history of Lebanon in its local, regional and
international context reflect Christian historical writing in 18th century Bilad
al-Sham. Al-Munayyir was able to rid himself of the confines of his religious
community and to view Lebanon as a unique, but fragile entity continuously
vulnerable to internal strife and external interference in its affairs
carried away : Love, bly, and secrecy in Henry James\u27 The Turn of the Screw
The function of the prologue in Henry Jamesâ The Turn of the Screw is decidedly ambiguous, as the characters in the prologue, much like the uncle of the main text, are seemingly never seen again. For this reason, the purpose of this prologue is much debated.1 As Rolf LundĂ©n states in his article ââNot in any literal, vulgar wayâ: The Encoded Love Story of Henry Jamesâ The Turn of the Screw,â âThe openness of Henry James\u27 The Turn of the Screw has invited more analytical attempts, and more critical controversy, than most literary textsâ (30). LundĂ©n summarizes four schools of thought regarding the interpretation of Jamesâ novella (30). The first is a metaphysical reading of the text, in which critics see the text as an actual ghost story. The second is a psychoanalytical interpretation of the novella, in which the Quint and Jessel function as a result of the governessâ sexually hysteric mind. A third, less popular, analysis of the text claims that Mrs. Grose is sabotaging the governess in order to take the governessâ position at Bly. The fourth reading of the text, according to LundĂ©n, contends that Miles lives, and Douglas and Miles are in fact the same person. I will argue that the prologue of The Turn of the Screw also seems to serve as an epilogue, an explanation of what happens after the conclusion of the main text. Douglas, the holder of the governessâ written story, is the only character who knows or comes into contact with the governess after Milesâ ambiguous death scene. However, Douglas, though he has read a text that implicates the governess as a potential murderer, describes her as âthe most agreeable woman Iâve ever known in her position; sheâd have been worthy of any whateverâ (24). This seeming confession to murder, in which âhis [Milesâ] little heart, dispossessed, had stoppedâ (120), thus does not appear to have any negative impact on Douglasâ opinion of the governess, engendering speculation as to what places the governess in his high regard. Douglas claims his association with the governess occurred over approximately one year, and âit was a beautiful oneâ (24). In this year, the two had, as Douglas casually puts it, âsome strolls and talks in the gardenâtalks in which she struck me as awfully clever and niceâ (24). These âsomeâ talks and walks, as described, do not seem intimate enough to provide the governess with enough comfort to tell Douglas a story âshe had never told anyoneâ (24), placing Douglasâ reliability as a narrator into suspicion.2 Therefore, it seems there must be more to the intimacy of the pair that is not shared with Douglasâ audience. This unrevealed closeness is further suggested in Douglasâ declaration of assurance that the governess had indeed never told this story to someone else; âI knew she hadnât, I was sure; I could seeâ (24). Douglasâ ability to know the truth just by glancing upon the governessâ face thus provides even more evidence of the great amount of intimacy implicit between the two. It is also important to note neither the first nor last name of the governess is ever given in the narrative or by Douglas. Secrecy regarding her identity is thus seemingly of the utmost importance; her name must remain concealed even after her death. Furthermore, as Douglas reveals, he even carries the key to the locked drawer which contains the narrative with him at all times; ââI shall have to send to townâŠI could write to my man and enclose the key; he could send down the packet as he finds itââ (23). His strong desire to protect the governessâ name and story is highly indicative of their suggested intimacy. Also, though Douglas himself did not write the narrative, he reveals that he does takes the impression of it; ââI took that hereââhe tapped his heart. âIâve never lost itââ (26). The seemingly permanent effect of this story on his heart highly suggests a personal involvement in it. The other characters of the prologue also speculate upon the relationship between Douglas and the governess. After insinuations of romance are made, one character claims, âShe was ten years older,â to which another responds âRaison de plusâ (25). Mrs. Griffin builds upon this idea, stating, âWell if I donât know who she was in love with I know who he wasâ (25), for the reason the prologueâs narrator deduces why the governess had not told anyone this story is not because it implicates her as a murderer, but, rather, because âshe was in loveâ (24). The major question by the end of the text thus remains: who was the governess in love with? Since she shares this story with Douglas, leaving him its written narrative, it seems as the governess is in love with Douglas. However, though the conclusion of The Turn of the Screw is as ambiguous as its prologue, what seems apparent is a romantic love that exists between the governess and her charge, Miles. In paralleling the seemingly reciprocated love that Douglas has for the governess with the governessâ love for Miles, I will argue that Douglas and Miles are the same person
Rethinking relationships in the construction industry : integrating sustainable development into project management processes
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