Determinants of the Organic Farmers' Demand for Hired Farm Labor

Labor and Human Capital,

Mathematical modelling of zika virus in Brazil

In this paper we study some deterministic mathematical models that seek to explain the expansion of zika virus, as a viral epidemic, using published data for Brazil. SIR type models are proposed and validated using the epidemic data found, considering several aspects in the spread of the disease. Finally, we confirmed that the crucial epidemic parameter such as $R_0$ is consistent with those previously reported in the literature for other areas. We also explored variations of the parameters within Brazil for different federal entities. We concluded that a parsimonious model that includes both human and vector populations best describe the epidemic parameters

Diversity across Seasons of Culturable Pseudomonas from a Desiccation Lagoon in Cuatro Cienegas, Mexico.

Cuatro Cienegas basin (CCB) is a biodiversity reservoir within the Chihuahuan desert that includes several water systems subject to marked seasonality. While several studies have focused on biodiversity inventories, this is the first study that describes seasonal changes in diversity within the basin. We sampled Pseudomonas populations from a seasonally variable water system at four different sampling dates (August 2003, January 2004, January 2005, and August 2005). A total of 70 Pseudomonas isolates across seasons were obtained, genotyped by fingerprinting (BOX-PCR), and taxonomically characterized by 16S rDNA sequencing. We found 35 unique genotypes, and two numerically dominant lineages (16S rDNA sequences) that made up 64% of the sample: P. cuatrocienegasensis and P. otitidis. We did not recover genotypes across seasons, but lineages reoccurred across seasons; P. cuatrocienegasensis was isolated exclusively in winter, while P. otitidis was only recovered in summer. We statistically show that taxonomic identity of isolates is not independent of the sampling season, and that winter and summer populations are different. In addition to the genetic description of populations, we show exploratory measures of growth rates at different temperatures, suggesting physiological differences between populations. Altogether, the results indicate seasonal changes in diversity of free-living aquatic Pseudomonas populations from CCB

Generation of Multi-Scroll Attractors Without Equilibria Via Piecewise Linear Systems

In this paper we present a new class of dynamical system without equilibria which possesses a multi scroll attractor. It is a piecewise-linear (PWL) system which is simple, stable, displays chaotic behavior and serves as a model for analogous non-linear systems. We test for chaos using the 0-1 Test for Chaos of Ref.12.Comment: Corresponding Author: Eric Campos-Cant\'o

Gender Bias Claims in Farm Service Agency’s Lending Decisions

This study analyzes the courts’ denial of women farmers’ motion for class-action certification of their lawsuits alleging gender discrimination in Farm Service Agency (FSA) lending decisions. The plaintiffs’ claim of “commonality†of circumstances in women farmers’ dealings with FSA is tested using a four-year sampling of Georgia FSA loan applications. The econometric framework has been developed after accounting for the separability of loan approval and amount decisions, as well as endogeneity issues through instrumental variable estimation. This study’s results do not produce overwhelming evidence of gender bias in FSA loan approval decisions and in favor of the “commonality†argument among Georgia FSA farm loan applicants.class-action suit, credit risk, creditworthiness, gender discrimination, Heckman selection, instrumental variable probit, Labor and Human Capital,

RENTAL PREMIUMS FOR SHARE VERSUS CASH LEASES

Non-risk factors primarily determine the probability of paying positive premiums to landowners for bearing greater risk under crop share versus cash leasing arrangements. The trends toward higher cash rent levels on larger farms may indicate that higher cash rent is a bidding strategy to control additional leased acreage and perhaps to avoid management sharing with multiple landlords. Expansion of farm size may be more important than soil productivity in negotiating higher cash rents, due to potential size economies and under utilized machinery investments.Land Economics/Use,

Racial Minority Lending Trends at the Farm Service Agency

A binomial logistic framework is used to determine important linkages between the FSA's decision on each loan application and the applicants financial and demographic attributes. Using data on both rejected and accepted FSA loan applications, empirical results indicate loan approval decisions were not significantly influenced by the borrowers' racial class and that, in contrast to the credit risk assessment standards employed by commercial lenders, the collective influence of more stringent and objective credit scoring measures on FSA loan approval decisions is insignificant.Agricultural Finance,

Foreign Workers and the Organic Farms’ Demand for Seasonal Unskilled Labor

This study analyzes farm labor management strategies of organic farms by employing Heckan selection model. Econometric results present interesting relationships between foreign worker-related variables and the hiring of non-family seasonal part-time workers. First, the extent of hiring is inversely related to the population of illegal residents. Second, the outcome variable (extent of hiring) is directly related to the number of H2A permits (foreign guest farm worker visas for temporary, contractual work) issued. The results also indicate that higher wages, corporate farms, and more educated, younger and full-time farm operators are associated with greater tendencies to hire non-family seasonal part-time workers. Family labor is used to supplement the lack of available non-family seasonal part-time workers.organic farm, unskilled labor, immigration, Heckman selection model, foreign worker, Farm Management,

A two-layer shallow water model for bedload sediment transport: convergence to Saint-Venant-Exner model

A two-layer shallow water type model is proposed to describe bedload sediment transport. The upper layer is filled by water and the lower one by sediment. The key point falls on the definition of the friction laws between the two layers, which are a generalization of those introduced in Fern\'andez-Nieto et al. (ESAIM: M2AN, 51:115-145, 2017). This definition allows to apply properly the two-layer shallow water model for the case of intense and slow bedload sediment transport. Moreover, we prove that the two-layer model converges to a Saint-Venant-Exner system (SVE) including gravitational effects when the ratio between the hydrodynamic and morphodynamic time scales is small. The SVE with gravitational effects is a degenerated nonlinear parabolic system. This means that its numerical approximation is very expensive from a computational point of view, see for example T. Morales de Luna et al. (J. Sci. Comp., 48(1): 258-273, 2011). In this work, gravitational effects are introduced into the two-layer system without such extra computational cost. Finally, we also consider a generalization of the model that includes a non-hydrostatic pressure correction for the fluid layer and the boundary condition at the sediment surface. Numerical tests show that the model provides promising results and behave well in low transport rate regimes as well as in many other situations