Abstract:
This paper contributes to the policy debate on minimum wage by highlighting its role in enforcing compliance with fiscal rules in economies where underreporting of earnings is widespread. First, I propose a simple model exploring the interaction between the minimum wage and underreporting of earnings. Then, I provide supportive evidence by documenting a positive correlation within European labour markets between the proportion of full-time employees with earnings on the minimum wage and the extent of underreporting of earnings in the economy. The analysis presented in this paper suggests that a high spike in the wage distribution at the minimum wage level is, in some contexts, a fiscal issue, more than a labour market issue, and therefore it would be incorrect to consider a high spike as an indication of a binding minimum wage. Also, differentiating the minimum wage along dimensions related to earnings (e.g. education, sector, or occupation) makes sense from an enforcement perspective.

Abstract:
In this talk new formulations of the Green--Schwarz heterotic strings in $D$ dimensions that involve commuting spinors, are reviewed. These models are invariant under $n$--extended, world sheet supersymmetry as well as under $N=1$, target space supersymmetry where $n\leq D-2$ and $D=3,4,6,10$. The world sheet supersymmetry replaces $n$ components (and provides a geometrical meaning) of the $\kappa$--symmetry in the Green--Schwarz approach. The models in $D=10$ for $n=1,2,8$ are discussed explicitly.

Abstract:
Português Este artigo busca analisar a rela o entre os pre os da soja no mercado físico, ao nível deprodutor e de atacado, da regi o de Maringá e do Porto de Paranaguá, no Estado do Paraná,com os pre os futuros da BM&F e da CBOT, no período de janeiro de 2003 a setembro de2008. A rela o entre os pre os físicos e futuros das localidades selecionadas foi analisada pormeio do cálculo do risco de base, do teste de causalidade de Granger e do cálculo da raz oótima e efetividade de hedge. O cálculo da base demonstrou que a base do contrato futuro daBM&F tende a se enfraquecer mais do que a base do contrato futuro da CBOT, no primeirosemestre do ano, e a se fortalecer mais no segundo semestre, no período analisado. Quanto aoteste de causalidade de Granger, observou-se uma rela o bicausal entre os pre os físicos efuturos e uma rela o unidirecional entre os pre os físicos. A análise da raz o ótima e daefetividade de hedge sugere que os contratos futuros da BM&F s o mais eficientes na redu ode riscos de pre o para os produtores das localidades selecionadas.English This article aims to examine the soybean spot price correlation between producers from theMaringá region and port of Paranaguá wholesalers, and the BM&F and CBOT future price indexes.The compiled data is referred to the period from January, 2003 to September, 2008.The relation between spot and future prices of the selected places was analyzed with the use ofbasis risk calculation, Granger test of causality and effectiveness and optimal ratio of hedge.The calculation demonstrated that the basis of the BM&F future contracts, in the first semesterof the years examined, tends to be less sustainable than the basis of the CBOT future contracts.This tendency is reversed in the second semester. As for the Granger test of causality, a bi-causalcorrelation was observed between the spot and future prices, and an unidirectional correlationobserved between spots prices. The analysis of the effectiveness and optimal ratio of hedgesuggests that the BM&F future contracts have a wider probability for price risk reduction.

Abstract:
The main purpose of this work is analyzing the role played by public finance policies in stimulating economic growth in Albania. Based on endogenous growth theory models is assessed the role played by public expenditure in growth performance in Albania relative to other transition economies with similar patterns of developments. The main findings of this study are: that macroeconomic stability of a country, trade openness, and investment in infrastructure are the main factors that have supported growth performance

Abstract:
We present a formulation of $N=1,D=10$ Supergravity--Super--Maxwell theory in superspace in which the graviphoton can be described by a 2--form $B_2$ or a 6--form $B_6$, the photon by a 1--form $A_1$ or a 7--form $A_7$ and the dilaton by a scalar $\varphi$ or an 8--form $\varphi_8$, the supercurvatures of these fields being related by duality. Duality interchanges Bianchi identities and equations of motion for each of the three couples of fields. This construction envisages the reformulation of $D=10$ Supergravity, involving 7--forms as gauge fields, conjectured by Schwarz and Sen, which, upon toroidal compactification to four dimensions, gives the manifestly $SL(2,R)_S$ invariant form of the heterotic string effective action.

Abstract:
The fields of the conjectured ``heterotic" super--fivebrane sigma--model in ten dimensions are made out of a well known gravitational sector, the $X$ and the $\vartheta$, and of a still unknown heterotic sector which should be coupled to the Yang--Mills fields. We compute the one--loop $d=6$ worldvolume and $D=10$ target space Lorentz--anomalies which arise from the gravitational sector of the heterotic super--fivebrane sigma--model, using a method which we developed previously for the Green--Schwarz heterotic superstring. These anomalies turn out to carry an overall coefficient which is $1/2$ of that required by the string/fivebrane duality conjecture. As a consequence the worldvolume anomaly vanishes if the heterotic fields consist of 16 (rather than 32) complex Weyl fermions on the worldvolume. This implies that the string/fivebrane duality conjecture can not be based on a ``heterotic" super--fivebrane sigma--model with only fermions in the heterotic sector. Possible implications of this result are discussed.

Abstract:
We determine the two--dimensional Weyl, Lorentz and $\kappa$--anomalies in the $D=10$ Green--Schwarz heterotic string sigma--model, in an $SO(1,9)$-Lorentz covariant background gauge, and prove their cancellation.

Abstract:
The quantum consistency of sigma-models describing the dynamics of extended objects in a curved background requires the cancellation of their world-volume anomalies, which are conformal anomalies for the heterotic string and $SO(1,5)$ Lorentz-anomalies for the heterotic five-brane, and of their ten dimensional target space anomalies. In determining these anomalies in a $D=10$ Lorentz-covariant back-ground gauge we find that for the heterotic string the worldvolume anomalies cancel for 32 heterotic fermions while for the conjectured heterotic five-brane they cancel for only 16 heterotic fermions, this result being in contrast with the string/five-brane duality conjecture. For what concerns the target space anomalies we find that the five-brane eight-form Lorentz-anomaly polynomial differs by a factor of $1/2$ from what is expected on the basis of duality. Possible implications of these results are discussed.

Abstract:
The twistor--like formulation of the type IIA superstring $\sigma$--model in D=10 is obtained by performing a dimensional reduction of the recently proposed twistor--like action of the supermembrane in D=11. The superstring action is invariant under local, worldsheet $(n,n)$ supersymmetry where $3\leq n \leq 8$ and is classical equivalent to the standard Green--Schwarz action (at least for $n=8)$