Aging and Immortality in a Cell Proliferation Model

We investigate a model of cell division in which the length of telomeres within the cell regulate their proliferative potential. At each cell division the ends of linear chromosomes change and a cell becomes senescent when one or more of its telomeres become shorter than a critical length. In addition to this systematic shortening, exchange of telomere DNA between the two daughter cells can occur at each cell division. We map this telomere dynamics onto a biased branching diffusion process with an absorbing boundary condition whenever any telomere reaches the critical length. As the relative effects of telomere shortening and cell division are varied, there is a phase transition between finite lifetime and infinite proliferation of the cell population. Using simple first-passage ideas, we quantify the nature of this transition.Comment: 6 pages, 1 figure, 2-column revtex4 format; version 2: final published form; contains various improvements in response to referee comment

Investor sentiment and trading behavior

The aim of this paper is to model trading decisions of financial investors based on a sentiment index. For this purpose, we analyse a dynamical model which includes the sentiment index in the agents' trading behavior. We consider the set up of a Discrete Dynamical System, assuming that in financial markets transactions take place between two groups of fundamentalists that differ in their perception of fundamental value. The proportion of fundamentalists in the two groups is assumed to depend on the sentiment index. The sentiment index used is related to the risk asymmetry index (RAX) enabling us to consider both the variance and the asymmetry of the prediction error between the two groups of fundamentalists. We identify the equilibria of the model and conduct a numerical analysis in order to capture stylized facts documented empirically in the financial literature

Fundamentalists heterogeneity and the role of the sentiment indicator

This paper is a contribution to the literature on the role of the sentiment indices in heterogeneous asset pricing models. We propose a new sentiment index in a financial market where we assume that transactions take place between two groups of fundamentalists that differentiate on the perception of the fundamental value. We assume that the fraction of fundamentalists in the two groups depends on the sentiment index. After studying the analytical properties of the deterministic discrete dynamical system we compare the new index with a previous index introduced in financial literature. For this purpose, by adding stochastic components to the fundamentalist' demands, we measure the performance of our model under different sentiment indices and we test its explanatory power to reproduce the stylized facts of financial data relying on the S&P500 index

Metastatic melanoma of the tongue: a rare case

Not availabl

Light emitting diodes technology in public light system of the municipality of Rome: an economic and financial analysis

This study evaluates an investment project concerning the redevelopment of the public lighting of the Municipality of Rome. In particular, we consider the replacing of the traditional lamps of the system with light emitting diodes lamps. We consider the factors that affect this kind of project: The cost of energy, the manteinance cost, the investment cost and the weighted average cost of capital. Our results underline the reduction of energy consumption and of the maintenance costs, lower emissions of CO2 into the atmosphere, the reduction of light pollution, the positive effects on road safety and the indipendence by incentives

Shari'ah-compliant finance: a possible novel paradigm for green economy investments in Italy

In Italy, the dramatic reduction of government incentives has caused a decrease of investments in the renewable energy sector. For this reason, it is necessary to rethink funding techniques, extending the analysis to different cultural and financial models. In this paper, we study the incentive-dependency of an Italian case study in the wind energy sector in order to reach grid parity, comparing the obtained results with those of Islamic finance and conventional finance. In particular, we propose that Sukuk Islamic finance instruments be used for the realization of real assets in Shari'ah-compliant finance that prohibits interest rates, as in conventional financial markets, and we present the building cost thresholds necessary to achieve grid parity. Our results highlight the importance of incentives and the applicability of the use of Sukuk instruments for sustainable investments in the wind energy sector, which is crucial in the framework of current efforts against climate change as well as efforts to reduce greenhouse gas emissions

Nickel and cobalt adsorption on hydroxyapatite: a study for the de-metalation of electronic industrial wastewaters

In the present study, the Ni(II) and Co(II) adsorption efficiency and selectivity, as well adsorption mechanisms on a stoichiometric hydroxyapatite (HAP) surface have been investigated. Characterization studies (N-2 adsorption/desorption and X-ray powder diffraction (XRPD) analyses) and adsorption tests under various operative conditions provided detailed information about the use of HAP in the de-metalation of wastewaters containing Ni and Co as polluted metal species. The sorption capacity of HAP has been evaluated by static batch adsorption tests varying initial concentration of Ni(II) and Co(II) species (from ca. 0.25 to 4.3mM), contact time (from 15min to 24h), and pH (from 4 to 9) operative parameters. Proposed mechanisms of adsorption of Ni(II) and Co(II) on HAP surface are ion-exchange and surface complexation; a partial contribution of chemical precipitation from bulk solution should be considered at pH 9. In addition, adsorption isotherms of Ni(II) and Co(II) on HAP have been collected at 30 degrees C and pH 4 and modeled by employing different equations. The maximum sorption capacities have been quantified as 0.317mmolgHAP-1 (18.6mggHAP-1) and 0.382mmolgHAP-1 (22.5mggHAP-1) for Ni(II) and Co(II), respectively. Selectivity to Co and Ni in the adsorption process on HAP has also been investigated; HAP has higher affinity towards Co than Ni species (Co:Ni=2.5:1, molar ratio)