5,514 research outputs found

    Quadratic A1A_1 bounds for commutators of singular integrals with BMO functions

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    For commutators of the form [b,T] where T is any Calderon--Zygmund operator and b is any BMO function we derive weighted quadratic type estimates in term of the A1 constant of the weight both in the Lp context or of LlogL type at the endpointComment: to appear in Indiana Journal, part of PhD thesi

    A new species of Anastrepha from Amazonia : with redescriptions of A. caudata Stone and A. hendeliana Lima (Diptera: Tephritidae)

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    Three species of Anastrepha from upper Amazonia are described or redescribed and illustrated. They are considered closely related and are placed in the A. caudata species group. Anastrepha caudata Stone 1942 is redescribed based on the holotype, the only known specimen. Its type locality is probably São Paulo de Olivença in Amazonas, Brazil, not the state or city of São Paulo as previously assumed. Anastrepha hendeliana Lima 1934, new status, is removed from synonymy with A. longicauda Lima 1934 based on specimens from Brazil (Amazonas and Rondonia) and Colombia (Caquetá). The female is described for the first time. Anastrepha brunnealata, n. sp., is described from specimens from Venezuela (Amazonas) and probably Peru (Loreto). Anastrepha longicauda Lima is placed in the dentata species group.Se describen o redescriben e ilustran tres especies de Anastrepha del Amazonia. Ellas están consideradas cercanamente relacionadas y las ubican en el grupo de especies caudata. Se redescribe Anastrepha caudata Stone 1942 basado en el holotipo, el único especimen conocido. La localidad tipo probablemente es São Paulo de Olivença en el Amazonas, Brasil, no el estado o la ciudad de São Paulo como se asumió anteriormente. Se remueve Anastrepha hendeliana Lima 1934, stat. n., de la sinonómia de A. longicauda Lima 1934 basado en especimenes de Brasil (Amazonas y Rondonia) y Colombia (Caquetá). La hembra es descrita por primera vez. Se describe Anastrepha brunnealata, sp. n., de especimenes de Venezuela (Amazonas) y probablemente Peru (Loreto). Se ubica Anastrepha longicauda Lima en el grupo de especies dentata

    Analysis of a stochastic 2D–Navier-Stokes model with infinite delay

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    Some results concerning a stochastic 2D Navier-Stokes system when the external forces contain hereditary characteristics are established. The existence and uniqueness of solutions in the case of unbounded (infinite) delay are first proved by using the classical technique of Galerkin approximations. The local stability analysis of constant solutions (equilibria) is also carried out by exploiting two approaches. Namely, the Lyapunov function method and by constructing appropriate Lyapunov functionals. The asymptotic stability and hence, the uniqueness of equilibrium solution are obtained by constructing Lyapunov functionals. Moreover, some sufficient conditions ensuring the polynomial stability of the equilibrium solution in a particular case of unbounded variable delay will be provided. Exponential stability for other special cases of infinite delay remains as an open problem.Ministerio de Economía y Competitividad (MINECO). EspañaJunta de AndalucíaNational Natural Science Foundation of ChinaScience and Technology Commission of Shanghai Municipalit

    Analysis of a stochastic SIR model with fractional Brownian motion

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    In this article, a stochastic version of a SIR nonautonomous model previously introduced in Kloeden and Kozyakin (2011) is considered. The noise considered is a fractional Brownian motion which satisfies the property of long range memory, which roughly implies that the decay of stochastic dependence with respect to the past is only subexponentially slow, what makes this kind of noise a realistic choice for problems with long memory in the applied sciences. The stochastic model containing a standard Brownian motion has been studied in Caraballo and Colucci (2016). In this paper, we analyze the existence and uniqueness of solutions to our stochastic model as well as their positiveness.Ministerio de Economía y CompetitividadFondo Europeo de Desarrollo RegionalJunta de Andalucí

    Systemic oversight frameworks in LAC : current practices and reform agenda

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    The world financial crisis that started in the US housing market in 2008 brought into evidence deep failures of prudential oversight, linked for the most part to a failure to comprehend and handle systemic risk in a way that could prevent systemic crises. This paper summarizes the responses to the joint World Bank -ASBA survey o the state of systemic oversight in the Latin American and Caribbean financial sectors and reflects on some of the challenges identified by respondents. We found that there is broad consensus among regional financial authorities on the need to enhance the current systemic oversight framework. Improving consolidated supervision to mitigate risk-shifting in conglomerates, adjusting prudential regulations to account for the accumulation of systemic risks, redefining the role of the supervisor to make it more proactive, and improving coordination among local supervisors as well as with foreign supervisors figure preeminently in the regional reform agenda.Banks&Banking Reform,Debt Markets,Emerging Markets,Access to Finance,Currencies and Exchange Rates

    Census of Active Commercial Fishermen in Puerto Rico: 2008

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    The implementation of Puerto Rican Regulation No. 6768, which overhauled the existing fishery management framework, generated considerable hostility towards local managers. Among the controversial management measures adopted in 2004 were the assignment of fishing licenses based on fishing income, the establishment of closed seasons, and new minimum size restrictions for commercially valuable species. Though tensions have subsided, considerable opposition to these regulations remains. This paper provides a characterization of the current population of active small-scale fishermen, discusses their perceptions about the biological and socio-economic condition of the fishery, and describes their attitudes towards the new management framework. This study revealed that the number of active fishermen decreased from 1,731 in 1988 to 868 in 2008. Although a declining resource base was one of the main drivers behind these waning participation statistics, rising fuel costs and burdensome regulations exacerbated the rate of attrition. The majority of the fishermen were middleaged men (50 years) with moderate levels of formal education and high levels of fishing dependence which limited their employment opportunities outside the fishery. Most of the vessels were small (20 ft) and outfitted with a single outboard engine (80 hp). Hook and line and SCUBA were dominant gears because of their versatility and cost effectiveness. Fishermen suggested that their opposition to the regulations would continue unless they were afforded greater regulatory flexibility and provided with a larger role in the decision-making process. Fishermen were adamant about the need to reconsider the income reporting requirements to secure a fishing license because of the potential for losing public assistance benefits. They also objected to increasing the minimum size of many deepwater snapper (Lutjanidae) and grouper (Serranidae) species because it forced them to discard dead fish, a practice they consider wasteful since these species do not survive the ascent to the surface once hooked

    Pullback attractor for a dynamic boundary non-autonomous problem with Infinite delay

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    In this work we prove the existence of solution for a p-Laplacian non-autonomous problem with dynamic boundary and infinite delay. We ensure the existence of pullback attractor for the multivalued process associated to the non-autonomous problem we are concerned. Finally, we also prove the existence of a more general attractor for the problem known as D-pullback attractor.Conselho Nacional de Desenvolvimento Científico e TecnológicoMinisterio de Economía y CompetitividadFondo Europeo de Desarrollo RegionalJunta de Andalucí

    The Determinants of Relative Price Variability: Further Evidence from Argentina

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    This paper analyses the relative price variability (here after, RPVI) for Argentina from 1960 to 1993. We have distinguished a first period (1960-1975) with a moderate and stable inflation and a second one (1975-1993) with four inflation regimes: moderateRelative price Variability, inflation regimes, markov switching model, inflation components

    Inflation and Supply Shocks in Spain: A Regional Approach

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    This paper analyses the effects of supply shocks on the Spanish inflation rate. Our goal is to determine if there is a homogeneous behaviour across regions with regard to that issue or if, on the contrary, there are regions more inflationary than others. In this sense, this paper tries to throw some light on the causes of the recent increase in the Spanish inflation rate and the relation of this fact with the evolution of oil prices. The methodology applied is based on the seminal paper of Ball and Mankiw (1995). Those authors assume that a good proxy for supply shocks is the third moment of the distribution of changes in relative prices, and show that for no trend inflation regimes the presence of nominal rigidities, like menu costs, implies a positive relationship between inflation and skewness -i.e., the supply shocks-, that is magnified by the variance of the distribution. In order to achieve these goals, we have chosen the 1993-2005 period, given that it fulfils the features required to apply the methodology above mentioned. The data used are the monthly consumer price indexes of each region, disaggregated in 57 categories. As a first stage, we have checked that the skewness of the distribution of changes in relative prices is a good proxy for supply shocks. After that, the relationship between inflation and the higher moments of the distribution is estimated. Moreover, control variables as interest rates and unemployment rates have been introduced. The analysis has been carried out in two ways. On one hand, each region is analysed separately and, on the other hand, we have used panel data techniques in order to test homogeneity across regions. Our results point out that Spanish regions show a common pattern with regard to inflation behaviour and that they are vulnerable to supply shocks.
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