Ricerca educativa e orientamento

Il contributo riflette sul ruolo della ricerca educativa nella formulazione delle politiche in \ue0mbito formativo, con specifico riferimento alla costruzione di un sistema nazionale di orientamento. Ci\uf2 \ue8 di significativa importanza per la scuola, a motivo della sua funzione orientativa che - sia a livello politico, sia sotto il profilo pedagogico - \ue8 concordemente giudicata il fulcro del suo agire educativo. In tale prospettiva, sono poste in luce alcune questioni di ricerca pedagogico-educativa connesse con la possibilt\ue0 di offrire a quanti hanno responsabilit\ue0 istituzionali strumenti per la progettazione e la gestione di un sistema istruttivo-formativo che sostenga i processi di orientamento/auto-orientamento messi in atto dai soggetti nel corso della carriera scolastica, dando particolare attenzione alle principali fasi di transizione fra i diversi ordini di scuola e fra questa e l\u2019universit\ue0 o il mondo del lavoro

Prospettive intorno all'orientamento: ricerca educativa e politiche pubbliche.

Il contributo intende offrire alcune sollecitazioni intorno al tema dell\u2019orientamento, con particolare riferimento al rapporto fra ricerca educativa e politiche pubbliche nell\u2019\ue0mbito del rinnovamento del sistema di istruzione e formazione. Tale rapporto \ue8 assai complesso: da un lato risulta erroneo concepirlo in termini deterministici, dall\u2019altro non sfugge l\u2019importanza di superare la reciproca diffidenza. \uc8 quindi opportuno e urgente che esso sia oggetto di indagine in \ue0mbito pedagogico con l\u2019obiettivo di mostrare che ciascuno degli \ue0mbiti/saperi coinvolti ha da un lato la necessit\ue0 di tutelare il proprio peculiare approccio, dall\u2019altro abbisogna di entrare in relazione con ogni altro nella continua ricerca di spazi di confronto che possano arricchirlo. Si paleserebbe cos\uec la possibilit\ue0 di uno spaziocomune che non pare improprio proporre nei termini di cultura per l\u2019orientamento intesa come patrimonio di conoscenze/esperienze teoriche, pra- tiche, scientifiche, politiche, programmatico-gestionali per progettare e attuare l\u2019orientamento nella forma di educazione permanente di quella tendenza perfettiva che \ue8 propria di ogni uomo e dell\u2019umanit\ue0 in quanto tali

Supersymmetric Extension of the Snyder Algebra

We obtain a minimal supersymmetric extension of the Snyder algebra and study its representations. The construction differs from the general approach given in Hatsuda and Siegel ({\tt hep-th/0311002}), and does not utilize super-de Sitter groups. The spectra of the position operators are discrete, implying a lattice description of space, and the lattice is compatible with supersymmetry transformations.Comment: 14 page

Superfield covariant analysis of the divergence structure of noncommutative supersymmetric QED4_4

Commutative supersymmetric Yang-Mills is known to be renormalizable for ${\cal N} = 1, 2$, while finite for ${\cal N} = 4$. However, in the noncommutative version of the model (NCSQED$_4$) the UV/IR mechanism gives rise to infrared divergences which may spoil the perturbative expansion. In this work we pursue the study of the consistency of NCSQED$_4$ by working systematically within the covariant superfield formulation. In the Landau gauge, it has already been shown for ${\cal N} = 1$ that the gauge field two-point function is free of harmful UV/IR infrared singularities, in the one-loop approximation. Here we show that this result holds without restrictions on the number of allowed supersymmetries and for any arbitrary covariant gauge. We also investigate the divergence structure of the gauge field three-point function in the one-loop approximation. It is first proved that the cancellation of the leading UV/IR infrared divergences is a gauge invariant statement. Surprisingly, we have also found that there exist subleading harmful UV/IR infrared singularities whose cancellation only takes place in a particular covariant gauge. Thus, we conclude that these last mentioned singularities are in the gauge sector and, therefore, do not jeopardize the perturbative expansion and/or the renormalization of the theory.Comment: 36 pages, 11 figures. Minor correction

Hilbert Space of Isomorphic Representations of Bosonized Chiral QCD2QCD_2

We analyse the Hilbert space structure of the isomorphic gauge non-invariant and gauge invariant bosonized formulations of chiral $QCD_2$ for the particular case of the Jackiw-Rajaraman parameter $a = 2$. The BRST subsidiary conditions are found not to provide a sufficient criterium for defining physical states in the Hilbert space and additional superselection rules must to be taken into account. We examine the effect of the use of a redundant field algebra in deriving basic properties of the model. We also discuss the constraint structure of the gauge invariant formulation and show that the only primary constraints are of first class.Comment: LaTeX, 19 page

Chiral Bosons Through Linear Constraints

We study in detail the quantization of a model which apparently describes chiral bosons. The model is based on the idea that the chiral condition could be implemented through a linear constraint. We show that the space of states is of indefinite metric. We cure this disease by introducing ghost fields in such a way that a BRST symmetry is generated. A quartet algebra is seen to emerge. The quartet mechanism, then, forces all physical states, but the vacuum, to have zero norm.Comment: 9 page

The noncommutative degenerate electron gas

The quantum dynamics of nonrelativistic single particle systems involving noncommutative coordinates, usually referred to as noncommutative quantum mechanics, has lately been the object of several investigations. In this note we pursue these studies for the case of multi-particle systems. We use as a prototype the degenerate electron gas whose dynamics is well known in the commutative limit. Our central aim here is to understand qualitatively, rather than quantitatively, the main modifications induced by the presence of noncommutative coordinates. We shall first see that the noncommutativity modifies the exchange correlation energy while preserving the electric neutrality of the model. By employing time-independent perturbation theory together with the Seiberg-Witten map we show, afterwards, that the ionization potential is modified by the noncommutativity. It also turns out that the noncommutative parameter acts as a reference temperature. Hence, the noncommutativity lifts the degeneracy of the zero temperature electron gas.Comment: 11 pages, to appear in J. Phys. A: Math. Ge

Chiral bosons and improper constraints

We argue that a consistent quantization of the Floreanini-Jackiw model, as a constrained system, should start by recognizing the improper nature of the constraints. Then each boundary conditon defines a problem which must be treated sparately. The model is settled on a compact domain which allows for a discrete formulation of the dynamics; thus, avoiding the mixing of local with collective coordinates. For periodic boundary conditions the model turns out to be a gauge theory whose gauge invariant sector contains only chiral excitations. For antiperiodoc boundary conditions, the mode is a second-class theory where the excitations are also chiral. In both cases, the equal-time algebra of the quantum energy-momentum densities is a Virasoro algebra. The Poincar\'e symmetry holds for the finite as well as for the infinite domain.Comment: 13 pages, Revtex file, IF.UFRGS Preprin

Attractive Forces Between Electrons in QED3_{3}

Vacuum polarization effects are non-perturbatively incorporated into the photon propagator to eliminate the severe infrared problems characteristic of QED$_3$. The theory is thus rephrased in terms of a massive vector boson whose mass is $e^2/(8\pi)$. Subsequently, it is shown that electron-electron bound states are possible in QED$_3$.Comment: revtex, 10 pages and four figures, IFUSP/P-98