22,828 research outputs found
AN EXPERIMENTAL INVESTIGATION OF GASEOUS-FILM COOLING OF A ROCKET MOTOR
Gaseous-film cooling of rocket combustion chambe
Using deuterated H3+ and other molecular species to understand the formation of stars and planets
The H3+ ion plays a key role in the chemistry of dense interstellar gas
clouds where stars and planets are forming. The low temperatures and high
extinctions of such clouds make direct observations of H3+ impossible, but lead
to large abundances of H2D+ and D2H+ which are very useful probes of the early
stages of star and planet formation. Maps of H2D+ and D2H+ pure rotational line
emission toward star-forming regions show that the strong deuteration of H3+ is
the result of near-complete molecular depletion of CNO-bearing molecules onto
grain surfaces, which quickly disappears as cores warm up after stars have
formed.
In the warmer parts of interstellar gas clouds, H3+ transfers its proton to
other neutrals such as CO and N2, leading to a rich ionic chemistry. The
abundances of such species are useful tracers of physical conditions such as
the radiation field and the electron fraction. Recent observations of HF line
emission toward the Orion Bar imply a high electron fraction, and we suggest
that observations of OH+ and H2O+ emission may be used to probe the electron
density in the nuclei of external galaxies.Comment: Proceedings of the H3+ centennial symposium, to be published in RSPTA
(editor: T. Oka
Distinguishing the opponents in the prisoner dilemma in well-mixed populations
Here we study the effects of adopting different strategies against different
opponent instead of adopting the same strategy against all of them in the
prisoner dilemma structured in well-mixed populations. We consider an
evolutionary process in which strategies that provide reproductive success are
imitated and players replace one of their worst interactions by the new one. We
set individuals in a well-mixed population so that network reciprocity effect
is excluded and we analyze both synchronous and asynchronous updates. As a
consequence of the replacement rule, we show that mutual cooperation is never
destroyed and the initial fraction of mutual cooperation is a lower bound for
the level of cooperation. We show by simulation and mean-field analysis that
for synchronous update cooperation dominates while for asynchronous update only
cooperations associated to the initial mutual cooperations are maintained. As a
side effect of the replacement rule, an "implicit punishment" mechanism comes
up in a way that exploitations are always neutralized providing evolutionary
stability for cooperation
Statistics of opinion domains of the majority-vote model on a square lattice
The existence of juxtaposed regions of distinct cultures in spite of the fact
that people's beliefs have a tendency to become more similar to each other's as
the individuals interact repeatedly is a puzzling phenomenon in the social
sciences. Here we study an extreme version of the frequency-dependent bias
model of social influence in which an individual adopts the opinion shared by
the majority of the members of its extended neighborhood, which includes the
individual itself. This is a variant of the majority-vote model in which the
individual retains its opinion in case there is a tie among the neighbors'
opinions. We assume that the individuals are fixed in the sites of a square
lattice of linear size and that they interact with their nearest neighbors
only.
Within a mean-field framework, we derive the equations of motion for the
density of individuals adopting a particular opinion in the single-site and
pair approximations. Although the single-site approximation predicts a single
opinion domain that takes over the entire lattice, the pair approximation
yields a qualitatively correct picture with the coexistence of different
opinion domains and a strong dependence on the initial conditions. Extensive
Monte Carlo simulations indicate the existence of a rich distribution of
opinion domains or clusters, the number of which grows with whereas the
size of the largest cluster grows with . The analysis of the sizes of
the opinion domains shows that they obey a power-law distribution for not too
large sizes but that they are exponentially distributed in the limit of very
large clusters. In addition, similarly to other well-known social influence
model -- Axelrod's model -- we found that these opinion domains are unstable to
the effect of a thermal-like noise
A Submillimeter HCN Laser in IRC+10216
We report the detection of a strong submillimeter wavelength HCN laser line
at a frequency near 805 GHz toward the carbon star IRC+10216. This line, the
J=9-8 rotational transition within the (04(0)0) vibrationally excited state, is
one of a series of HCN laser lines that were first detected in the laboratory
in the early days of laser spectroscopy. Since its lower energy level is 4200 K
above the ground state, the laser emission must arise from the inner part of
IRC+10216's circumstellar envelope. To better characterize this environment, we
observed other, thermally emitting, vibrationally excited HCN lines and find
that they, like the laser line, arise in a region of temperature approximately
1000 K that is located within the dust formation radius; this conclusion is
supported by the linewidth of the laser. The (04(0)0), J=9-8 laser might be
chemically pumped and may be the only known laser (or maser) that is excited
both in the laboratory and in space by a similar mechanism.Comment: 11 pages, 3 figure
Euroescepticismo en el Parlamento Europeo: un estudio de la actuación euroescéptica en las elecciones europeas (2009-2019)
This paper analyses the progression of eurosceptic groups within the European Parliament between 2009 and 2019. Through pre-established definitions of Euroscepticism as a political phenomenon, we conduct a quantitative and qualitative analysis, which gathers data from the official results of 3 European legislative elections (2009, 2014 and 2019) and later interprets them with the aid of previous academic production on eurosceptic values and strategies within the European Union’s institutions. As a conclusion, we seek to demonstrate that Euroscepticism is a consequence of a greater scenario, which relates to a gradual loss of public trust in the European political establishment.Este trabajo analiza la progresión de los grupos euroescépticos en el Parlamento Europeo entre 2009 y 2019. A través de definiciones preestablecidas del Euroescepticismo como fenómeno político, hacemos un análisis cuantitativo y cualitativo que recopila datos de los resultados oficiales de 3 elecciones legislativas europeas (2009, 2014 y 2019) y que luego los interpreta con el auxilio de la producción académica previa sobre los valores y estrategias euroescépticas en las instituciones de la Unión Europea. Como conclusión, buscamos demostrar que el Euroescepticismo es una consecuencia de un contexto mayor, el cual se relaciona a una pérdida gradual de confianza pública en el establecimiento político europeo.Instituto de Relaciones Internacionale
Quasi-Lie schemes and Emden--Fowler equations
The recently developed theory of quasi-Lie schemes is studied and applied to
investigate several equations of Emden type and a scheme to deal with them and
some of their generalisations is given. As a first result we obtain t-dependent
constants of the motion for particular instances of Emden equations by means of
some of their particular solutions. Previously known results are recovered from
this new perspective. Finally some t-dependent constants of the motion for
equations of Emden type satisfying certain conditions are recovered
Observatório de Democracias
VII Seminário de Extensão Universitária da UNILA (SEUNI); VIII Encontro de Iniciação Científica e IV Encontro de Iniciação em Desenvolvimento Tecnológico e Inovação (EICTI 2019) e Seminário de Atividades Formativas da UNILA (SAFOR)O projeto Observatório de Democracias tem como objetivo prover dados
sistematizados e atualizados sobre democracia e observação eleitoral no
MERCOSUL, além de fornecer análises sobre a temática, permitindo que os
cidadãos e os decisores dos países do bloco disponham de informações
qualificadas para adotar decisões relacionadas às políticas públicas ligadas à
democraciaO projeto Observatório de Democracias agradece solenemente a
Universidade Federal da Integração Latino Americana (UNILA), especialmente a pró
reitoria de extensão (PROEX), por financiar o projeto e fazer possível essa propost
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