1,355,847 research outputs found
The Lamperti transformation for self-similar processes
No full textIn this paper we establish the uniqueness of the Lamperti transformation leading from self-similar to stationary processes, and conversely. We discuss alpha-stable processes, which allow to understand better the difference between the Gaussian and non-Gaussian cases. As a by-product we get a natural construction of two distinct alpha-stable Ornstein–Uhlenbeck processes via the Lamperti transformation for 0Lamperti transformation; Self-similar process; Stationary process; Stable distribution;
Empirical validation of simulated models through the GSL-div: An illustrative application
No full textA major concern about the use of simulation models regards their relationship with the empirical data. The identification of a suitable indicator quantifying the distance between the model and the data would help and guide model selection and output validation. This paper proposes the use of a new criterion, called GSL-div and developed in Lamperti (2015), to assess the degree of similarity between the dynamics observed in the data and those generated by the numerical simulation of models. As an illustrative application, this approach is used to distinguish between different versions of the well known asset pricing model with heterogeneous beliefs proposed in Brock and Hommes (1998). Once the discrimination ability of the GSL-div is proved, model's dynamics are directly compared with actual data coming from two major stock market indexes (EuroSTOXX 50 for Europe and CSI 300 for China). Results show that the model, once calibrated, is fairly able to track the evolution of both the two indexes, even though a better fit is reported for the Chinese stock market. However, I also find that many different combinations of traders behavioural rules are compatible with the same observed dynamics. Within this heterogeneity, an emerging common trait is found: to be empirically valid, the model has to account for a strong trend following component, which might either come from a unique trend type that heavily extrapolates information from past observations or the combinations of different types with milder, or even opposite, attitudes towards the trend
Sabedoria vocal: máximas de Giovanni Battista Lamperti, mestre de Marcela Sembrich, Stagno, Hanstreiter e outros cantores famosos
No full textUnavailable.FUJBSabedoria vocal é um texto fundamental da pedagogia vocal mundial. Através das ideias expostas no livro, entramos em contato direto com os conceitos técnicos de um dos maiores professores de canto do século XX: Giovanni Battista Lamperti. Grande parte do que os professores de canto falam em suas aulas hoje está contida neste livro de uma maneira ou de outra. Não vamos encontrar uma descrição fisiológica do aparelho fonador com nomenclaturas musculares em suas páginas. Este é um livro sobre uma possível filosofia do canto mais do que um manual pedagógico. Lamperti sugere, encaminha e incita o leitor a refletir. E justamente aí está seu maior valor
Collective excitability, synchronization, and array-enhanced coherence resonance in a population of lasers with a saturable absorber
No full textIn this article we present a numerical study of the collective dynamics in a population of coupled semiconductor lasers with a saturable absorber, operating in the excitable regime under the action of additive noise. We demonstrate that temporal and intensity synchronization takes place in a broad region of the parameter space and for various array sizes. The synchronization is robust and occurs even for a set of nonidentical coupled lasers. The cooperative nature of the system results in a self-organization process which enhances the coherence of the single element of the population too and can have broad impact for detection purposes, for building all-optical simulators of neural networks and in the field of photonics-based computation
Rate of escape and central limit theorem for the supercritical Lamperti problem
No full textThe study of discrete-time stochastic processes on the half-line with mean drift at x given by μ1(x)→0 as x→∞ is known as Lamperti's problem. We give sharp almost-sure bounds for processes of this type in the case where μ1(x) is of order x−β for some β(0,1). The bounds are of order t1/(1+β), so the process is super-diffusive but sub-ballistic (has zero speed). We make minimal assumptions on the moments of the increments of the process (finiteness of (2+2β+ε)-moments for our main results, so fourth moments certainly suffice) and do not assume that the process is time-homogeneous or Markovian. In the case where xβμ1(x) has a finite positive limit, our results imply a strong law of large numbers, which strengthens and generalizes earlier results of Lamperti and Voit. We prove an accompanying central limit theorem, which appears to be new even in the case of a nearest-neighbour random walk, although our result is considerably more general. This answers a question of Lamperti. We also prove transience of the process under weaker conditions than those that we have previously seen in the literature. Most of our results also cover the case where β=0. We illustrate our results with applications to birth-and-death chains and to multi-dimensional non-homogeneous random walks
Connected TV: a resources and competences approach
No full textThe extensive use of the Internet, and in particular of the broadband connection, is encouraging the creation of new, more dynamic and interactive television models, ones that more closely mirror the needs and desires of the viewer. This is achieved through new technologies offering better services as well as improved quality. As is typical of “connected” worlds (like Internet, cinema, etc.), the concentration of many features on one form of media – in this case the TV - is increasingly spreading. This phenomena commonly known as the "digital revolution", is due to the many drastic changes that have occurred in the television industry. The convergence of the traditional TV and the Web worlds has given way to the Connected TV. The process of hybridization between audiovisual diffusion systems, interactive services and the possibility to use several different services directly from television terminals has begun taking shape.
The new concept of television is called "Over the Top TV" (OTT TV): it represents the opportunity for integration between regularly programmed TV and on-demand contents. OTT TV includes broadband services which enable the delivery of videos through a broadband connection.
This paper, focusing in particular on the scenario of the Connected TV, aims to answer two questions: first, "What kind of resources, competences and skills are needed in these new markets?" and second, "Do successful business models exist that can be replicated by different players?".
Through the analysis of existing literature, the study of secondary sources and the investigation of more than thirty cases in the Italian Media Industry, the authors have identified the core resources and competences (R/Cs) essential for gaining a competitive advantage in the Connected TV arena, and have shed some light on some of the more interesting business models.
In particular, a support tool has been created based on the following six steps: i) a general map has been drawn illustrating the necessary resources and competences characterising the sector; ii) the Connected TV’s Critical Success Factors (CSFs) have been identified; iii) the CSFs that have an impact on a company’s objectives have been selected; iv) the critical resources and competences for a specific company have been individuated; v) the core resources and competences, that is to say a subset of the critical resources and competences that have passed specific tests, have been selected; vi) the match between the R/Cs individuated and the corporate objectives established has been verified.
Finally, the support tool has been tested in a real case and it has proven useful in helping the company to better understand its core competences, taking into account its specific objectives
Disorder-induced localization of excitability in an array of coupled lasers
No full textWe report on the localization of excitability induced by disorder in an array of coupled semiconductor lasers with a saturable absorber. Through numerical simulations we show that the exponential localization of excitable waves occurs if a certain critical amount of randomness is present in the coupling coefficients among the lasers. The results presented in this Rapid Communication demonstrate that disorder can induce localization in lattices of excitable nonlinear oscillators, and can be of interest in the study of photonics-based random networks, neuromorphic systems, and, by analogy, in biology, in particular, in the investigation of the collective dynamics of neuronal cell populations
The Lamperti Transform: Applications to Stochastic Local Volatility Models
No full textThis thesis showcases a rather contemporary method of solving a generalized system of stochastic differential equations (SDE's) comparable to the SABR model. The solution is derived from a stochastic-local volatility (SLV) model in which the local volatility (LV) component is kept general. This generality is maintained throughout all derivations, eventually yielding a model containing an undefined LV function. This function can then be specified however the user of the model deems suitable, as long as minor constraints are satisfied. Obviously, this is a very valuable quality of the model as it is highly customizable. The solution consists of a set of pricing functions that seemingly possess all the aforementioned desirable properties, i.e. fast in evaluation, computational tractability, flexibility etc., with little disadvantages. The generalized SLV model that is used is typically denoted in the form of two SDE's, though in the majority of this thesis an atypical three SDE form is used. This extended system is used to isolate the LV component, in turn enabling for appropriate application of an SDE transformation called the Lamperti transform, which will provide the key to solving the entire system. The Lamperti transform is a highly versatile method for transforming SDE's into new equations typically more suitable for simulation and parameter estimation procedures, and its inner-workings and various applications will be the main focus of this thesis.Applied Mathematics | Financial Engineerin
Pholcus lamperti Strand 1907
No full text42. Pholcus lamperti Strand, 1907. Tanzania (Strand 1907; Simon & Fage 1922; Huber 2011).Published as part of Bernhard A. Huber & Charles M. Warui, 2012, East African pholcid spiders: an overview, with descriptions of eight new species (Araneae, Pholcidae), pp. 1-44 in European Journal of Taxonomy 29 (29) on page 10, DOI: 10.5852/ejt.2012.29, http://zenodo.org/record/140663
Beyond climate economics orthodoxy: impacts and policies in the agent-based integrated-assessment DSK model*
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