Organic Agriculture as Livelihood Strategy: A Case Study in a Rural Community of Southern Brazil

This paper presents the findings of a case study of a Brazilian community pursuing a livelihood strategy based on certified organic agriculture. Using the sustainable rural livelihoods framework, the paper identifies three different organic livelihood strategies involving varying degrees of capitals. The paper concludes that understanding the implications of these different organic strategies and their rationales is a prerequisite for policy-makers to tailor policies and programmes aiming to assist rural communities benefit from organic agriculture as a vehicle for advancing rural development

Spanning tests in return and stochastic discount factor mean-variance frontiers: A unifying approach

We propose new spanning tests that assess if the initial and additional assets share the economically meaningful cost and mean representing portfolios. We prove their asymptotic equivalence to existing tests under local alternatives. We also show that unlike two-step or iterated procedures, single-step methods such as continuously updated GMM yield numerically identical overidentifyng restrictions tests, so there is arguably a single spanning test. To prove these results, we extend optimal GMM inference to deal with singularities in the long run second moment matrix of the influence functions. Finally, we test for spanning using size and book-to-market sorted US stock portfolios.Asset Pricing, Continuously Updated GMM, Generalised Empirical Likelihood, Generalised Inverse, Representing Portfolios, Singular Covariance Matrix

Duality in mean-variance frontiers with conditioning information

Portfolio and stochastic discount factor (SDF) frontiers are usually regarded as dual objects, and researchers sometimes use one to answer questions about the other. However, the introduction of conditioning information and active portfolio strategies alters this relationship. For instance, the unconditional portfolio frontier in Hansen and Richard (1987) is not dual to the unconditional SDF frontier in Gallant, Hansen and Tauchen (1990). We characterise the dual objects to those frontiers, and relate them to the frontiers generated with managed portfolios, which are commonly used in empirical work. We also study the implications of a safe asset and other special cases.Asset Pricing, Dynamic Portfolio Strategies, Representing portfolios, Stochastic Discount Factors

A unifying approach to the empirical evaluation of asset pricing models

Two main approaches are commonly used to empirically evaluate linear factor pricing models: regression and SDF methods, with centred and uncentred versions of the latter. We show that unlike standard two-step or iterated GMM procedures, single-step estimators such as continuously updated GMM yield numerically identical values for prices of risk, pricing errors, Jensen’s alphas and overidentifying restrictions tests irrespective of the model validity. Therefore, there is arguably a single approach regardless of the factors being traded or not, or the use of excess or gross returns. We illustrate our results by revisiting Lustig and Verdelhan’s (2007) empirical analysis of currency returns.CU-GMM, Factor pricing models, Forward premium puzzle, Generalised Empirical Likelihood, Stochastic discount factor.

On the impact of fundamentals, liquidity and coordination on market stability

We develop a coordination game to model interactions between fundamentals and liquidity during unstable periods in financial markets. We then propose a flexible econometric framework for estimation of the model and analysis of its quantitative implications. The specific empirical application is carry trades in the yen–dollar market, including the turmoil of 1998. We find a generally very deep market, with low information disparities amongst agents. We observe occasionally episodes of market fragility, or turmoil with up by the escalator, down by the elevator patterns in prices. The key role of strategic behavior in the econometric model is also confirmed.global games, efficient method of moments, carry trades, tail risk, strategic behavior, financial crises

On the drivers of commodity co-movement: Evidence from biofuels

We use the recent introduction of biofuels to study the effect of industry factors on the relationships between wholesale commodity prices. Correlations between agricultural products and oil are strongest in the 2005-09 period, coinciding with the boom of biofuels, and remain substantial until 2011. We disentangle three possible drivers for the linkage: substitution, energy costs, and financialization. The timing and magnitude of the biofuels-to-oil relationships are different to those of other commodities, and far higher than can be justified by costs and financialization. Substitution and costs drive the monthly correlations of long-term futures, and each of the three contribute equally to the daily co-movement of the short-term ones. The findings survive many robustness checks and appear in the stock market.biofuels, commodities, co-movement, ethanol, oil, structural breaks

Quantifying wave-function overlaps in inhomogeneous Majorana nanowires

A key property of Majorana zero modes is their protection against local perturbations. In the standard picture, this protection is guaranteed by a high degree of spatial nonlocality of the Majoranas, namely a suppressed wave-function overlap, in the topological phase. However, a careful characterization of resilience to local noise goes beyond mere spatial separation and must also take into account the projection of wave-function spin. By considering the susceptibility of a given zero mode to different local perturbations, we find the relevant forms of spin-resolved wave-function overlaps that measure its resilience. We quantify these overlaps and study their dependence with nanowire parameters in several classes of experimentally relevant configurations. These include nanowires with inhomogeneous depletion and induced pairing, barriers, and quantum dots. Smooth inhomogeneities have been shown to produce near-zero modes, so-called pseudo-Majoranas, below the critical Zeeman field in the bulk. Surprisingly, their resilience is found to be comparable or better than that of topological Majoranas in realistic systems. We further study how accurately their overlaps can be estimated using a purely local measurement on one end of the nanowire, accessible through conventional transport experiments. In uniform nanowires, this local estimator is remarkably accurate. In inhomogeneous cases, it is less accurate but can still provide reasonable estimates for potential inhomogeneities of the order of the superconducting gap. We further analyze the zero-mode wave-function structure, spin texture, and spectral features associated with each type of inhomogeneity. All our results highlight the strong connection between internal wave-function degrees of freedom, nonlocality, and protection in smoothly inhomogeneous nanowiresWe acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through Grants No. FIS2015-65706-P, No. FIS2015-64654-P, and No. FIS2016-80434-P (AEI/FEDER, EU), the Ramón y Cajal programme, Grants No. RYC-2011-09345 and No. RYC-2013-14645, and the “María de Maeztu” Programme for Units of Excellence in Research and Development (MDM-2014-0377

Gender equity: A challenge for universities

The objective of the research is to evaluate the previous knowledge that teachers and administrative staff of the Universidad Francisco de Paula Santander Ocaña have about a social problem such as gender-based violence, for which a descriptive study with a cross-sectional quantitative approach was undertaken, developed in three phases: a first phase begins with the theoretical support related to gender equity, a second phase has the quantitative analysis of the variables by applying a questionnaire to a finite sample of teachers and administrative staff on the topic of study. The results show that in spite of the strategies implemented by the institution to guarantee gender equity in its academic community, this is blurred by the fact that the majority of the university bodies confuse the definition of sex with gender and most of them do not have a clear understanding of the meaning of equality and equity. Likewise, the high lack of knowledge of the institutional route for a victim of gender-based violence resulting in not knowing how to act and protect their integrity and that of their academic community, adding that very few know about the five types of gender-based violence such as physical, psychological, economic, sexual and verbal violence