Hypergeometric Functions over Finite Fields and their relations to Algebraic Curves

In this work we present an explicit relation between the number of points on a family of algebraic curves over \F_{q} and sums of values of certain hypergeometric functions over \F_{q}. Moreover, we show that these hypergeometric functions can be explicitly related to the roots of the zeta function of the curve over \F_{q} in some particular cases. A general conjecture relating these last two is presented and advances toward its proof are shown in the last section.Comment: 24 page

On string integrability. A journey through the two-dimensional hidden symmetries in the AdS/CFT dualities

One of the main topics in the modern String Theory are the AdS/CFT dualities. Proving such conjectures is extremely difficult since the gauge and string theory perturbative regimes do not overlap. In this perspective, the discovery of infinitely many conserved charges, i.e. the integrability, in the planar AdS/CFT has allowed us to reach immense progresses in understanding and confirming the duality. We review the fundamental concepts and properties of integrability in two-dimensional sigma-models and in the AdS/CFT context. The first part is focused on the AdS_5/CFT_4 duality, especially the classical and quantum integrability of the type IIB superstring on AdS_5 x S^5 are discussed in both pure spinor and Green-Schwarz formulations. The second part is dedicated to the AdS_4/CFT_3 duality with particular attention to the type IIA superstring on AdS_4 x CP^3 and its integrability. This review is based on a shortened and revised version of the author's PhD thesis, discussed at Uppsala University in September 2009.Comment: 116 pages, 11 figures, to be published in Advances in High Energy Physics, Special Issue on ''Gauge/String Duality'

Governance and Performance of Microfinance Institutions in Central and Eastern Europe and the Newly Independent States

This paper presents the first evidence on the impact of board diversity and independence, and management compensation on outreach and sustainability of microfinance institutions in Central and Eastern Europe and the Newly Independent States. Results indicate that board diversity improves both outreach and sustainability while larger and less independent boards lower sustainability. Performance-based compensation is not effective in aligning the interest of managers and stakeholders, and underpaying managers reduces outreach.governance, microfinance, board of directors, managerial compensation, Financial Economics,

Investment in Young and Established Microenterprises in Russia

This paper shows that imperfections in the credit market and insecurity of property rights affect nonuniformly the investment of younger and established microenterprises in Russia. The empirical analysis of investment is based on the liquidity constraint model but also accounts for the added challenged that the weak institutional structure and the small size of the enterprises pose. Investment in younger firms is most constrained by the availability of funds, while investment in more established microenterprises is affected by the ability of the entrepreneurs to "secure" their property rights by paying bribes. Financial institutions are unable to distinguish good from bad borrowers but lend to firms that have transparent transactions.Agricultural Finance,

INVESTMENTS AND PROPERTY RIGHTS IN RUSSIA: EVIDENCE FROM SMALL FIRMS IN SAMARA

This study establishes empirically that the financial restrictions faced by micro and small entrepreneurs in Russia influence their investment decisions. Survey data from 305 entrepreneurs are used to identify credit market imperfections resulting from asymmetric information.Resource /Energy Economics and Policy,

Governance and Performance of Microfinance Institutions in Central and Eastern Europe and the Newly Independent States

This paper studies how various governance mechanisms affect the performance of microfinance institutions in Central and Eastern Europe and the Newly Independent States. Results show that managerial compensation matters, that market forces are becoming important disciplining device, and that board size, diversification and independence affect both outreach and sustainability.Financial Economics,

PERFORMANCE AND GOVERNANCE OF COMMUNITY DEVELOPMENT FINANCIAL INSTITUTIONS

This paper investigates the influence of board size and board diversity on the performance of Community Development Financial Institutions' operating in the Southeast. The results indicate that at present many CDFI boards are larger than optimal. The results also show that CDFIs generally have well diversified boards and that these organizations' performance is unlikely to improve by further diversifying their boards. However, CDFIs performance may be improved by promoting smaller boards.Financial Economics,

Rating in Microfinance: Cross-Country Evidence

This paper studies whether microfinance rating agencies were able to impose market discipline on microfinance institutions (MFIs) during the period 1998-2002. Results indicate that not all rating agencies had equal impact. While some rating agencies were able to promote better sustainability, there is some weak evidence that rating by a particular rater might have induce moral hazard, whereby after receiving good rating, MFIs had worse performance perhaps because in some regions several raters operated simultaneously. Evidence also suggests that subsidized rating does not encourage improvements in sustainability and has negative impact on outreach. Rating by some individual raters helped MFIs to raise additional funds.Financial Economics,

Rating in Microfinance: Cross Country Evidence

This paper focuses on the ability of microfinance rating agencies to impose market discipline on microfinance institutions by rating these organizations' performance. Results indicate that not all rating agencies are equal as only one rater was able to impose market discipline by promoting better sustainability, while rating by another agency caused MFIs to slack off. In addition, while rating in general lead to better outreach, this effect was annulled if MFIs received financial aid in order to get rated. Finally, only one rater provided rating that allowed MFIs to raise additional debtFinancial Economics,