294 research outputs found

    An Improved Two-Party Negotiation Over Continues Issues Method Secure Against Manipulatory Behavior

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    This contribution focuses on two-party negotiation over continuous issues. We firstly prove two drawbacks of the jointly Improving Direction Method (IDM), namely that IDM is not a Strategy-Proof (SP) nor an Information Concealing (IC) method. Thus we prove that the concurrent lack of these two properties implies the actual non-efficiency of IDM. Finally we propose a probabilistic method which is both IC and stochastically SP thus leading to efficient settlements without being affected by manipulatory behaviors

    On the Actual Inefficiency of Efficient Negotiation Methods

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    In this contribution we analyze the effect that mutual information has on the actual performance of efficient negotiation methods. Specifically, we start by proposing the theoretical notion of Abstract Negotiation Method (ANM) as a map from the negotiation domain in itself, for any utility profile of the parties. ANM can face both direct and iterative negotiations, since we show that ANM class is closed under the limit operation. The generality of ANM is proven by showing that it captures a large class of well known in literature negotiation methods. Hence we show that if mutual information is assumed then any Pareto efficient ANM is manipulable by one single party or by a collusion of few of them. We concern about the efficiency of the resulting manipulation. Thus we find necessarily and sufficient conditions those make manipulability equivalent to actual inefficiency, meaning that the manipulation implies a change of the efficient frontier so the Pareto efficient ANM converges to a different, hence actually inefficient, frontier. In particular we distinguish between strong and weak actual inefficiency. Where, the strong actual inefficiency is a drawback which is not possible to overcome of the ANMs, like the Pareto invariant one, so its negotiation result is invariant for any two profiles of utility sharing the same Pareto frontier, we present. While the weak actual inefficiency is a drawback of any mathematical theorization on rational agents which constrain in a particular way their space of utility functions. For the weak actual inefficiency we state a principle of Result's Inconsistency by showing that to falsify theoretical hypotheses is rational for any agent which is informed about the preference of the other, even if the theoretical assumptions, which constrain the space of agents' utilities, are exact in the reality, i.e. the preferences of each single agent are well modeled

    On the efficient application of the repeated Richardson extrapolation technique to option pricing

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    Richardson extrapolation (RE) is a commonly used technique in financial applications for accelerating the convergence of numerical methods. Particularly in option pricing, it is possible to refine the results of several approaches by applying RE, in order to avoid the difficulties of employing slowly converging schemes. But the effectiveness of such a technique is fully achieved when its repeated version (RRE) is applied. Nevertheless, its application in financial literature is pretty rare. This is probably due to the necessity to pay special attention to the numerical aspects of its implementation, such as the choice of both the sequence of the stepsizes and the order of the method. In this contribution, we consider several numerical schemes for the valuation of American options and investigate the possibility of an appropriate application of RRE. As a result, we find that, in the analyzed approaches in which the convergence is monotonic, RRE can be used as an effective tool for improving significantly the accuracy.Richardson extrapolation, repeated Richardson extrapolation, American options, randomization technique, flexible binomial method

    Nou factor predictiu del càncer prostàtic

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    Aquest estudi conclou que, en pacients amb biòpsies prostàtiques i amb diagnòstic de neoplàsia intraepitelial prostàtica d'alt grau, l'expressió d'un nou gen, conegut com PTOV1, és un bon factor predictiu de càncer i condicionarà la rebiòpsia immediata.Este estudio concluye que, en pacientes con biopsias prostáticas y diagnóstico de neoplasia intraepitelial prostática de alto grado, la expresión de un nuevo gen, conocido como PTOV1, es un buen factor predictivo de cáncer de próstata y condicionará la rebiopsia inmediata

    Soluzioni tecnologiche per la gestione del Fund Raising: un'analisi comparativa

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    Sono numerose le architetture di database alla base di software per l'ottimizzazione dell'attivita' di fund raising, strategica per le organizzazioni non profit. Con la realizzazione di un'analisi comparativa dei principali prodotti, si intende fornire uno strumento operativo per la scelta tra le diverse soluzioni disponibili o per la realizzazione di un prodotto personalizzato. I risultati dell'analisi consentono inoltre di individuare i presupposti per lo studio specifico del caso italiano.fund raising; software; analisi comparativa; prodotto personalizzato

    A Recommender System for fund raising management

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    In fund raising management the use of rigorous mathematical methods and decision support systems has been playing a more and more important role. These techniques develop the classical data base approach proposed by the operational literature. These improvements concern both the mathematical modeling associated with the information management techniques and the specic characteristics of the Associations, with the consequent specializations of the algorithms. In this approach, the role of the potential donors (i.e. contacts) and the process for turning the contacts into actual donors in the context of the so called "giving pyramid" was poorly investigated, despite its high importance in particular from a strategic point of view. In this contribution, we develop a recommender system that uses similarity measures to optimize the contacts' management. This is achieved by a proper use of the information contained in the Association data base, which concern the profiles of those donors that are suitable for the current campaign, and by matching these with the profiles of the contacts by similarity. The similarity among the (normalized) profiles will be realized by a suitable distance-based function. Numerical results show the effectiveness of the proposed approach

    Characteristics of some Phytophthora species isolated from oak forest soils in central and northern Italy.

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    Four Phytophthora species, P. citricola, P. megasperma, P. quercina and P. syringae, were isolated during a systematic survey of oak forests (Quercus cerris and Q. robur) in Tuscany (central Italy), and in the Po Valley and the Venetian Plain (northern Italy) from 22 out of 54 soil samples. The main morphological characteristics of the isolates and their growth rates on different substrates and at different temperatures are reported

    Autocontamination trap with entomopathogenic fungi: a possible strategy in the control of Rhynchophorus ferrugineus (Olivier) (Coleoptera Curculionidae)

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    An experimental autocontamination trap was devised to infect Rhynchophorus ferrugineus (Olivier), the Red Palm Weevil, adults with entomopathogenic fungi. The aim was to develop an autocontamination device to support integrated R. ferrugineus control programs. In laboratory bioassays, the delivery system successfully attracted, infected and released weevil adults after they contacted cereal substrata inoculated with indigenous strains of Beauveria bassiana (Balsamo- Crivelli) Vuillemin and Metarhizium anisopliae (Metchnikoff) Sorokin. Tests carried out with the experimental traps showed that M. anisopliae was the more virulent pathogen, causing 75% cumulative mortality in adults, while B. bassiana gave a 45% cumulative mortality. Infectivity of M. anisopliae was not affected by different cereal substrata, i.e. wheat and rice, since curculionid cumulative mortality (95%) and treatment efficiency (95% Abbott) were very high on both of them and Red Palm Weevil LT50 was reached within the same time (15 days). Conidial persistence and germinability of M. anisopliae grown on the rice substratum were examined in field conditions inside traps located in sunny and shady positions in spring, summer and autumn. The results showed that the traps preserved fungal inoculum stability longer in spring and summer than in autumn. No significant difference in M. anisopliae conidial persistence was found between sunny and shady traps during the various seasons

    Crystal structural and optical properties of Cr-doped Y2Ti2O7 and Y2Sn2O7 pyrochlores

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    Pyrochlore-type [A(2)(VIII)B(2)(VI)O(6)O] rare earth stannates (PS) and titanates (PT), doped with increasing amounts of Cr, develop colours 2 2 ranging from magenta to brown. Combined X-ray and neutron diffraction data revealed that Cr solubility in both pyrochlores is very limited, i.e. 0.07 atoms/formula unit in PS and 0.06 atoms/formula unit in PT. A further increase in the Cr amount determines the formation of the YCrO3 perovskite. Diffuse reflectance spectroscopy data showed that the optical properties of Cr-doped yttrium titanates and stannates are rather similar, and that the final colour of the powders is due to the overlapping peaks of Cr4+ in the octahedral site of the pyrochlore and of Cr3+ in the ternary perovskite. The oxygen occupancy refinement showed that no anion vacancies are formed upon Cr substitution for Sn4+ or Ti4+, implying that such a charge compensation mechanism does not occur, confirming that the Cr in titanate and stannate pyrochlores is mainly in a tetravalent state

    Metarhizium anisopliae biopesticides and fungus isolates: control efficacy against Rhynchophorus ferrugineus (Olivier) (Coleoptera Dryophthoridae) on different contamination substrata.

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    The lack of biological insecticides based on Metarhizium anisopliae (Metsch.) Sorokin registered in Italy for the control of the Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier), prompted studies to evaluate the efficacy of two commercial products, Met52® and BioStormTM and of their fungal isolates, M. anisopliae (Man52) and (ManBS) respectively, against the adults. The virulence of the M. anisopliae strains (Man52) and (ManBS) was compared with that of an indigenous M. anisopliae (Man08/I05) strain obtained from R. ferrugineus specimens collected in the wild and that showed to be very virulent against the RPW in previous studies. In both tests the sublethal effects of the treatments on female reproductive potential were examined in relation to the infective substratum. Laboratory results indicated that the commercial formulations mixed directly into the soil were not active in transmitting the infection to RPW adults and in reducing female fecundity and fertility. Diversely the fungal M. anisopliae (ManBS), (Man52) and (Man08/I05) strains inoculated on a rice substratum caused over 80% mortality of the phytophagous. In particular, M. anisopliae (ManBS) and the M. anisopliae (Man08/I05) produced the highest mortality (100%), with LT50 e LT90 reached in 3 and 6 days respectively. M. anisopliae (Met52) strain instead led to 85% mortality of RPW specimens in 28-days but it took longer to reach LT50 (6 days) and LT90 (12 days). The reproductive potential of females infected with the fungal strains was also significantly reduced with respect to the control. This study indicates the possibility of using also M. anisopliae strains in use against other insects of agricultural importance, for the control of R. ferrugineus although their effectiveness is conditioned by the formulations and/or methods employed against the RPW
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