Intermittency of trawl processes

We study the limiting behavior of continuous time trawl processes which are defined using an infinitely divisible random measure of a time dependent set. In this way one is able to define separately the marginal distribution and the dependence structure. One can have long-range dependence or short-range dependence by choosing the time set accordingly. We introduce the scaling function of the integrated process and show that its behavior displays intermittency, a phenomenon associated with an unusual behavior of moments

Cues from the extracellular space: matrix proteins regulate melanoma invasion

Melanoma is the most aggressive type of skin cancer with increasing incidence rates. To date, there are no effective therapies that can ensure disease free or even progression free survival of melanoma patients. While early stage primary melanoma is curable by surgical resection, survival of patients with metastatic melanoma is measured in months. Therefore it is of utmost importance to decipher molecular events that precede and/or induce the switch towards the invasive melanoma phenotype. In pursue of efficient therapy, attention has to be given not only to the cancer cells themselves but also to the microenvironment that nurtures and promotes malignant behavior. Aggressive melanoma cells drastically remodel their microenvironment. We found that expression of two extracellular matrix (ECM) proteins was significantly altered in melanoma compared to uninvolved patient skin: Tenascin C (TNC) was markedly increased, while small proteoglycan Decorin (DCN) was decreased. We found that invasion of the melanoma cells correlates with TNC expression levels and that cells present TNC asymmetrically at the invasive fronts. We also found that Epidermal Growth Factor-Like (EGFL) repeats of TNC promote melanoma cell invasiveness by activating Rho-associated kinase and increasing cell contractility, thus allowing mesenchymal to amoeboidal switch in mode of migration. Interestingly, TNC and DCN have both been shown to affect signaling through Epidermal Growth Factor receptor (EGFR), but with opposite outcomes on cell proliferation, migration and survival. We adapted skin organ cultures to test the influence of these two proteins on melanoma invasion and found that DCN can ameliorate TNC induced melanoma invasion. Taken together, our findings imply that ECM composition has a significant role in the regulation of melanoma invasiveness and that even in the presence of increased pro-invasive TNC signaling DCN can be a promising moiety for melanoma therapy

The multifaceted behavior of integrated supOU processes: the infinite variance case

The so-called "supOU" processes, namely the superpositions of Ornstein-Uhlenbeck type processes are stationary processes for which one can specify separately the marginal distribution and the dependence structure. They can have finite or infinite variance. We study the limit behavior of integrated infinite variance supOU processes adequately normalized. Depending on the specific circumstances, the limit can be fractional Brownian motion but it can also be a process with infinite variance, a L\'evy stable process with independent increments or a stable process with dependent increments. We show that it is even possible to have infinite variance integrated supOU processes converging to processes whose moments are all finite. A number of examples are provided.Accepted manuscrip

Intermittency of Superpositions of Ornstein-Uhlenbeck Type Processes

The phenomenon of intermittency has been widely discussed in physics literature. This paper provides a model of intermittency based on L\'evy driven Ornstein-Uhlenbeck (OU) type processes. Discrete superpositions of these processes can be constructed to incorporate non-Gaussian marginal distributions and long or short range dependence. While the partial sums of finite superpositions of OU type processes obey the central limit theorem, we show that the partial sums of a large class of infinite long range dependent superpositions are intermittent. We discuss the property of intermittency and behavior of the cumulants for the superpositions of OU type processes

Intermittency and infinite variance: the case of integrated supOU processes

SupOU processes are superpositions of Ornstein-Uhlenbeck type processes with a random intensity parameter. They are stationary processes whose marginal distribution and dependence structure can be specified independently. Integrated supOU processes have then stationary increments and satisfy central and non-central limit theorems. Their moments, however, can display an unusual behavior known as "intermittency". We show here that intermittency can also appear when the processes have a heavy tailed marginal distribution and, in particular, an infinite variance

Limit theorems, scaling of moments and intermittency for integrated finite variance supOU processes

Superpositions of Ornstein-Uhlenbeck type (supOU) processes provide a rich class of stationary stochastic processes for which the marginal distribution and the dependence structure may be modeled independently. We show that they can also display intermittency, a phenomenon affecting the rate of growth of moments. To do so, we investigate the limiting behavior of integrated supOU processes with finite variance. After suitable normalization four different limiting processes may arise depending on the decay of the correlation function and on the characteristic triplet of the marginal distribution. To show that supOU processes may exhibit intermittency, we establish the rate of growth of moments for each of the four limiting scenarios. The rate change indicates that there is intermittency, which is expressed here as a change-point in the asymptotic behavior of the absolute moments.Comment: Stochastic Processes and their Application

Tranzicija javnih preduzeća u Mađarskoj: Pravno – fnansijski aspekti

Ex-socialist governments created an unselective scale of public enterprises that were controlled and bureaucratically managed by ideological coordinates. They preferred big enterprises with all economic activities organized in huge systems based on market emulation or illusion. Pre-1989 socialist states had small numbers of private enterprises like small craft workshops but no small businesses as we understand them employing 10 to 100 workers. This paper covers the organization of public enterprises in the former socialist state Hungary. Former socialist states underwent a painful but inevitable transition process after the Berlin Wall came down in 1989 and the massive Communist illusion was lifted and brought the collapse of former regimes as the domino effect swathed through the states of Eastern Europe. In these countries the economies collapsed too, along with the public enterprises that were the causes and consequences of major upheaval after several unsuccessful decades of experimentation. There is a whole spectrum of different kinds of public enterprises organized according to historical epochs, ideologies, geographic areas, economic systems or specifc states. The current era is characterized by the presence of many kinds of public enterprises that vary from state to state or from case to case. In order to gain a better understanding of the various types of public enterprises we have to organize them into two general groups of states and political systems: the developing states, including former socialist economies and states in transition, and developed industrial states with market economies. Of course this paper covers only the main represents of public enterprises in Hungary. Looking at patterns of economic reform in ex-socialist state in the last decade of the Second Millennium, we see the public sector of the economy being defned on the basis of a narrower meaning of the general public interest of the citizens and the abandonment of the socialist delusion that the whole economy was of public interest. At the passage between two millenniums, the public sector of the economy is generally being understood and defned to reflect the parameters of the market economy. The Hungarian legislation places public enterprises under the authority of the local or national government, so the departments of that government are responsible for establishing these enterprises. The legislators have retained the main public businesses and services under government control, with public ownership at no less than 50+1% or in exceptional cases no less than 25+1%: in some cases government retains a priority vote or “golden share.” In former socialist state the concept of public enterprise began to take shape with the process of ownership transformation in the early 1990s: previous decades had espoused an ideological non-selective system that made whole countries into single quasi-public economies. As the privatization process matured, governments began to see the public economy clearly as a very important and special economic sector. A review of legislation in the former socialist state reveals the lawmakers’ goal of attracting private and mainly foreign capital into their public economies. Foreign investment as well as new technologies and equipment are prerequisites for transforming the old state frms into effcient businesses and services. Concession is a transparent and recognizably market institution that provides investors with security compared to short or long-term loans in transitional countries. The fnal word on the effectiveness of concessions in the campaign for foreign investment, however, has yet to be pronounced. The main Hungarian public energy and communications companies are the Power Plant Company or MVM Rt., the Telecommunications Company or MATAV Rt. and the national railroad or MAV Rt. These companies became assets of APV Rt. when this state agency was established as the engine of privatization in 1995. According to a December 19, 2000 statement by Prime Minister Victor Orban, the privatization process has been completed in Hungary and ownership structures now parallel those of the states of Western Europe. About 80% of public enterprises have been privatized in the last decade and the plan is to retain the rest as state properties.Tema ovog rada obuhvata pravno-fnansijske aspekte tranzicije javnih preduzeća u Mađarskoj. Cilj rada je istraživanje procesa restruktuiranja i privatizacije javnih preduzeća energetike i komunikacija u zemlji tranzicije koja je postala članica Evropske Unije. Autor ima cilj da osvetli iskustva, utvrdi benefcije i probleme jedne od najuspešnijih tranzicija bivših socijalističkih zemalja. Tema zahteva jedan odgovoran, utemeljen pristup sagledavanja niza aspekata, motivacije, okruženja u razumevanju aktuelnog pravno-ekonomskog procesa u Mađarskoj koji je rezultirao uspešnom integracijom u Evropsku Uniju. Namera je da se potakne stimulativna debata o reformi javnih preduzeća na putu evropskih integracija. Tema ovog rada je opravdana sa naučnog i društvenog aspekta