Can the Inflaton and the Quintessence scalar be the same field?

The most recent cosmological data point in the direction of a cosmological constant dominated universe. A suitable candidate for providing the required acceleration is a rolling scalar field named ``quintessence''. We address the issue of building a particle physics model for quintessence in the context of Susy QCD. We then go on to ask if the quintessence scalar can be identified with the inflaton field and give two examples in which this is indeed the case.Comment: 4 pages. Talk given at COSMO99, Trieste, Italy, September 1999. To appear in the Proceeding

Supersymmetric Quintessence

Recent data point in the direction of a cosmological constant dominated universe. We investigate the role of supersymmetric QCD with N_f < N_c as a possible candidate for dynamical cosmological constant (``quintessence''). We take in full consideration the multi-scalar nature of the model, allowing for different initial conditions for the N_f independent scalar VEVs and studying the coupled system of N_f equations of motion. The issues related to the coupling of the scalars with other cosmological fields are also addressed.Comment: 8 pages, JHEP LaTex format. To appear in the Proceeding of the "Trieste Meeting of the TMR Network on Physics beyond the SM", Trieste, 24-25 February 199

Reasoning about Minimal Belief and Negation as Failure

We investigate the problem of reasoning in the propositional fragment of MBNF, the logic of minimal belief and negation as failure introduced by Lifschitz, which can be considered as a unifying framework for several nonmonotonic formalisms, including default logic, autoepistemic logic, circumscription, epistemic queries, and logic programming. We characterize the complexity and provide algorithms for reasoning in propositional MBNF. In particular, we show that entailment in propositional MBNF lies at the third level of the polynomial hierarchy, hence it is harder than reasoning in all the above mentioned propositional formalisms for nonmonotonic reasoning. We also prove the exact correspondence between negation as failure in MBNF and negative introspection in Moore's autoepistemic logic

Improving crop productivity in agroforestry systems: low leaf respiration is a key trait

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Some Exact Results on the Ultrametric Overlap Distribution in Mean Field Spin Glass Models (I)

The mean field spin glass model is analyzed by a combination of mathematically rigororous methods and a powerful Ansatz. The method exploited is general, and can be applied to others disordered mean field models such as, e.g., neural networks. It is well known that the probability measure of overlaps among replicas carries the whole physical content of these models. A functional order parameter of Parisi type is introduced by rigorous methods, according to previous works by F. Guerra. By the Ansatz that the functional order parameter is the correct order parameter of the model, we explicitly find the full overlap distribution. The physical interpretation of the functional order parameter is obtained, and ultrametricity of overlaps is derived as a natural consequence of a branching diffusion process. It is shown by explicit construction that ultrametricity of the 3-replicas overlap distribution together with the Ghirlanda-Guerra relations determines the distribution of overlaps among s replicas, for any s, in terms of the one-overlap distribution.Comment: 17 pages, submitted to Euro. Phys. Jou. B Direc

A note on welfare and the economic shocks

The behaviour of the permanent and transitory economic shocks for different levels of household's welfare is studied using both consumption and income measures. After testing for heteroskedasticity of the economic shocks, we use local polynomial regression models to estimate the variance of the shocks conditional on welfare level. Italian data covering the period 1980-2004 show evidence of heteroskedasticity of both the transitory and the permanent economic shocks, with the poor experiencing higher variances. The permanent shocks seem to have a more uniform effect at all welfare levels.

Query-based comparison of OBDA specifications

An ontology-based data access (OBDA) system is composed of one or more data sources, an ontology that provides a conceptual view of the data, and declarative mappings that relate the data and ontology schemas. In order to debug and optimize such systems, it is important to be able to analyze and compare OBDA specifications. Recent work in this direction compared specifications using classical notions of equivalence and entailment, but an interesting alternative is to consider query-based notions, in which two specifications are deemed equivalent if they give the same answers to the considered query or class of queries for all possible data sources. In this paper, we define such query-based notions of entailment and equivalence of OBDA specifications and investigate the complexity of the resulting analysis tasks when the ontology is formulated in DL-LiteR