EXPLAINING THE ADOPTION AND DISADOPTION OF SUSTAINABLE AGRICULTURE: THE CASE OF COVER CROPS IN NORTHERN HONDURAS

Although technology adoption has been the subject of a great deal of economic research, that focused on the economics of adoption of low-input "sustainable" systems has been much more limited and recent. This paper attempts to explain the recent decline in the use of cover crops using in maize farming in the Department of Atlantida, Honduras. In the early 1970's, farmers in the region began rotating maize with the velvetbean (mucuna ssp.), a system learned from Guatemalan immigrants. Tohe mucuna-maize system decreased the labor required for maize farming even as it increased yields, prevented erosion, and conferred a variety of other agronomic benefits. By 1992, estimates show that the system had diffused among more than 60% of farmers in the Department. Both due to this widespread dissemination, and the fact that diffusion was largely spontaneous (unassisted by extensions and NGOs), the maize-mucuna system has become a widely acknowledged "success story" of sustainable agriculture diffusion. However, recent anecdotal evidence, confirmed by the survey research reported here, shows that by the late 1990s, use of the system had begun to decline sharply. Various hypotheses about the cause of this decline were investigated in this research, including whether the abandonment of the mucuna-maize system is attributable to a generalized decline in maize cultivation, changes in land tenure and distribution, a burgeoning cattle industry, infrastructural improvements, widespread infestations of noxious weed (rottboellia cochinchinensis), or limitations in farmer management. Modeling techniques evaluated two land-use decisions: whether to adopt mucuna-maize and the contingent decision of whether to abandon the system, once adopted. Bivariate probit analysis is used in the econometric analysis. Descriptive statistics and econometric results indicate that age, level of income from non-maize sources, the presence of rottboellia, and access to a road or highway are significantly related to the abandonment of overcropping. Meanwhile, greater dedication to maize, diversification into high value crops, greater experience with the system, and annual reseeding of mucuna are associated with continued use of the mucuna-maize rotation. The empirical results overall demonstrate that the phenomenon of maize-muchuna adoption and abandonment is a highly complex process. The results have policy implications for the "farmer to farmer" model of extension as well as the promotion of mucuna-maize as a sustainable agriculture technique. In the first case, less emphasis on diffusion and greater attention to farmer-to-farmer teaching of crop system dynamics may be important for the durability of cover crop systems. Regarding the second, cover crop species like mucuna should not be viewed as "silver bullet" solution to sustaining low-input agriculture: indeed, exclusive rotation of mucuna with maize may eliminate critical sources of plant and animal species diversity, ultimately undermining the system itself.International development, Sustainable agriculture, Adoption, Disadoption, Farmer management, Crop Production/Industries,

Speeding-up a quantum refrigerator via counter-diabatic driving

We study the application of a counter-diabatic driving (CD) technique to enhance the thermodynamic efficiency and power of a quantum Otto refrigerator based on a superconducting qubit coupled to two resonant circuits. Although the CD technique is originally designed to counteract non-adiabatic coherent excitations in isolated systems, we find that it also works effectively in the open system dynamics, improving the coherence-induced losses of efficiency and power. We compare the CD dynamics with its classical counterpart, and find a deviation that arises because the CD is designed to follow the energy eigenbasis of the original Hamiltonian, but the heat baths thermalize the system in a different basis. We also discuss possible experimental realizations of our model.Comment: 9 pages, 8 figure

Method for Determining Optimum Injector Inlet Geometry

A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The method calculates the tangential inlet area for each throttleable stage. The method also uses correlation between the tangential inlet areas and delta pressure values to calculate the spring displacement and variable inlet geometry of a liquid rocket engine swirl injector

Injector Element which Maintains a Constant Mean Spray Angle and Optimum Pressure Drop During Throttling by Varying the Geometry of Tangential Inlets

A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The tangential inlet area for each throttleable stage is calculated. The correlation between the tangential inlet areas and delta pressure values is used to calculate the spring displacement and variable inlet geometry. An injector designed using the method includes a plurality of geometrically calculated tangential inlets in an injection tube; an injection tube cap with a plurality of inlet slots slidably engages the injection tube. A pressure differential across the injector element causes the cap to slide along the injection tube and variably align the inlet slots with the tangential inlets

Quantum limit of photothermal cooling

We study the problem of cooling a mechanical oscillator using the photothermal (bolometric) force. Contrary to previous attempts to model this system, we take into account the noise effects due to the granular nature of photon absorption. This allows us to tackle the cooling problem down to the noise dominated regime and to find reasonable estimates for the lowest achievable phonon occupation in the cantilever

Charge Exchange Spectra of Hydrogenic and He-like Iron

We present H-like Fe XXVI and He-like Fe XXV charge-exchange spectra resulting from collisions of highly charged iron with N2 gas at an energy of 10 eV/amu in an electron beam ion trap. Although individual high-n emission lines are not resolved in our measurements, we observe that the most likely level for Fe25+ --> Fe24+ electron capture is n~9, in line with expectations, while the most likely value for Fe26+ --> Fe25+ charge exchange is significantly higher. In the Fe XXV spectrum, the K-alpha emission feature dominates, whether produced via charge exchange or collisional excitation. The K-alpha centroid is lower in energy for the former case than the latter (6666 versus 6685 eV, respectively), as expected because of the strong enhancement of emission from the forbidden and intercombination lines, relative to the resonance line, in charge-exchange spectra. In contrast, the Fe XXVI high-n Lyman lines have a summed intensity greater than that of Ly-alpha, and are substantially stronger than predicted from theoretical calculations of charge exchange with atomic H. We conclude that the angular momentum distribution resulting from electron capture using a multi-electron target gas is significantly different from that obtained with H, resulting in the observed high-n enhancement. A discussion is presented of the relevance of our results to studies of diffuse Fe emission in the Galactic Center and Galactic Ridge, particularly with ASTRO-E2/Suzaku.Comment: 16 pages, 4 figures (3 color), accepted by Ap

Why did you choose those readings? A case study in text selection for first year university students

This paper evaluates the reading and vocabulary demands in five texts used in a first-­year undergraduate paper in hospitality management at a multicultural university in New Zealand. There were two research perspectives: the students and the teaching materials. The student perspective investigated the length of time that students have studied in English language environments and their English-­language reading abilities; and how this may impact on a student's evaluation of selected texts and student reading time. The second perspective evaluated vocabulary frequency using an electronic vocabulary tool, the Vocabprofile. The two sets of data were then compared. The results revealed that self-­assessed reading ability in English related to student first language abilities, and demonstrated that the Vocabprofile can benefit text selection (Laufer & Nation, 1995;; Meara, 1993; Meara & Fitzpatrick 2000;; Meara, Lightbrown, & Halter, 1997) as well as provide a knowledge base for lecturers scaffolding reading materials. As student vocabulary skills and reading comprehension levels impact on subsequent academic success (Scarcella & Zimmerman, 1998), the comprehensive results of this research will find ready application within the social sciences and more qualitatively focussed domains of student study