7,186 research outputs found
On the double and triple-humped fission barriers and half-lives of actinide elements
The deformation barriers standing in the quasi-molecular shape path have been
determined in the actinide region within a macroscopic-microscopic energy
derived from a generalized liquid drop model, the algebraic droplet model shell
corrections and analytic expressions for the pairing energies. Double and
triple-humped fission barriers appear. The second barrier corresponds to the
transition from one-body shapes to two touching ellipsoids. The third minimum
and third peak, when they exist, come from shell rearrangements in the deformed
fragment. The shape of the other almost magic one is close to the sphere. The
barrier heights agreewith the experimental results, the energy of the second
minimum being a little too high. The predicted half-lives follow the
experimental data trend
Endogenous Credit Constraints and Factor Market Rigidities: the case of Bankruptcy
We develop a simple analytical model that highlights the effect of factor rigidities and credit constraints on bankruptcies. In our model, entrepreneurs receive random shocks –positive or negative-- to their working capital, which is needed to pay workers before the output of the firm is sold. If an entrepreneur receives a shock that lowers his working capital sufficiently, she requires loans in order to pay workers and continue operating. However, if the level of working capital is too low, Tirole’s (2000) condition implies the entrepreneur will not receive the necessary loans, due to moral hazard. In this case, the firm must adapt the number of workers to the available funds by firing workers, it is to survive. In the presence of labor rigidities, this may not be possible and the firm goes bankrupt. We show that there are several categories of entrepreneurs, depending on the magnitude of the shock: entrepreneurs who go bankrupt, entrepreneurs that can borrow but not enough to achieve their optimal capital-labor ratio, entrepreneurs that borrow but reach their optimal capital-labor ratio and finally entrepreneurs with that are the creditors in the financial market. We examine the effects of an increase in the labor rigidity on the demand for credit and on the efficiency of the economy. In a second stage, we simulate numerically the costs of these rigidities for sensible parameter values, to estimate bounds to the effects of the interactions between labor rigidity and credit constraints.Credit constraints, rigidities, bankruptcy
State of the art of pricing policy in air transportation: network carriers vs. low-cost airlines
The modern air transport industry is highly competitive. To survive in the market, the implementation of a successful marketing strategy is fundamental. In particular, an effective pricing policy has become crucial for airlines to remain profitable. Correspondingly, the different types of airline in the market have also established very distinct pricing policies. The present study is based on a literature review and presents the state of the art of pricing policy in air transportation. The aim is to compare and discuss the pricing strategies of network carriers and low-cost airlines. Special attention is paid to Revenue Management, which is a very important management tool used by airlines to take advantage of the differences in willingness to pay of passengers. The pricing policy, however, depends on the overall business strategy of the airline. Results show many differences, resulting from the fact that these two types of airline are characterized by very different fundamental business models and, correspondingly, also target groups. Since network carriers and also low-cost airlines have adjusted their pricing strategies lately, these recent developments will be discussed as well. This paper adds to the knowledge of this topic because it presents the most up-to-date and complete study on pricing regarding network carriers vs. low-cost airlines.A moderna indústria do transporte aéreo é altamente competitiva. Para
sobreviver no mercado, a implementação de uma estratégia de marketing
bem-sucedida é fundamental. Em particular, uma política de preços eficaz
tornou-se crucial para as companhias aéreas continuarem lucrativas. Os
diferentes tipos de companhias aéreas no mercado também
estabeleceram políticas de preços muito distintas. O presente estudo
baseia-se numa revisão da literatura e apresenta o estado da arte da
política de preços no transporte aéreo. O objetivo é comparar e discutir
as estratégias de preços de companhias aéreas de linha e companhias
aéreas de baixo custo. Atenção especial é dada à Gestão de Receitas
(Revenue Management), que é uma ferramenta de gestão usada pelas
companhias aéreas para aproveitar as diferenças na disposição de pagar
dos passageiros. A política de preços, no entanto, depende da estratégia
geral de negócios da companhia aérea. Os resultados mostram muitas
diferenças, resultantes do facto de que esses dois tipos de companhias
aéreas são caracterizados por modelos de negócios fundamentais muito
diferentes e, correspondentemente, também grupos-alvo. Como as
operadoras de rede e também as companhias aéreas de baixo custo
ajustaram as suas estratégias de preços ultimamente, esses
desenvolvimentos recentes também serão discutidos. Este documento
contribui para o conhecimento deste tópico, pois apresenta o estudo mais
atualizado e completo sobre preços de companhias aéreas de linha versus
companhias aéreas de baixo custo.info:eu-repo/semantics/publishedVersio
Mean Li-Yorke chaos in Banach spaces
We investigate the notion of mean Li-Yorke chaos for operators on Banach
spaces. We show that it differs from the notion of distributional chaos of type
2, contrary to what happens in the context of topological dynamics on compact
metric spaces. We prove that an operator is mean Li-Yorke chaotic if and only
if it has an absolutely mean irregular vector. As a consequence, absolutely
Ces\`aro bounded operators are never mean Li-Yorke chaotic. Dense mean Li-Yorke
chaos is shown to be equivalent to the existence of a dense (or residual) set
of absolutely mean irregular vectors. As a consequence, every mean Li-Yorke
chaotic operator is densely mean Li-Yorke chaotic on some infinite-dimensional
closed invariant subspace. A (Dense) Mean Li-Yorke Chaos Criterion and a
sufficient condition for the existence of a dense absolutely mean irregular
manifold are also obtained. Moreover, we construct an example of an invertible
hypercyclic operator such that every nonzero vector is absolutely mean
irregular for both and . Several other examples are also presented.
Finally, mean Li-Yorke chaos is also investigated for -semigroups of
operators on Banach spaces.Comment: 26 page
Tsallis and Kaniadakis statistics from a point of view of the holographic equipartition law
In this work, we have illustrated the difference between both Tsallis and
Kaniadakis entropies through cosmological models obtained from the formalism
proposed by Padmanabhan, which is called holographic equipartition law.
Similarly to the formalism proposed by Komatsu, we have obtained an extra
driving constant term in the Friedmann equation if we deform the Tsallis
entropy by Kaniadakis' formalism. We have considered initially Tsallis entropy
as the Black Hole (BH) area entropy. This constant term may lead the universe
to be in an accelerated mode. On the other hand, if we start with the
Kaniadakis entropy as the BH area entropy and then by modifying the Kappa
expression by Tsallis' formalism, the same constant, which shows that the
universe have an acceleration is obtained. In an opposite limit, no driving
inflation term of the early universe was derived from both deformations.Comment: 8 pages, preprint format. Final version to appear in Europhysics
Letter
Chaos in resonant-tunneling superlattices
Spatio-temporal chaos is predicted to occur in n-doped semiconductor
superlattices with sequential resonant tunneling as their main charge transport
mechanism. Under dc voltage bias, undamped time-dependent oscillations of the
current (due to the motion and recycling of electric field domain walls) have
been observed in recent experiments. Chaos is the result of forcing this
natural oscillation by means of an appropriate external microwave signal.Comment: 3 pages, LaTex, RevTex, 3 uuencoded figures (1.2M) are available upon
request from [email protected], to appear in Phys.Rev.
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