Agronomic research and productivity growth in post green revolution agriculture

This dissertation presents a methodology for measuring the impact of crop management research on agricultural productivity. The relationship between specific research projects and increases in producer surplus are identified. The methodology is used to derive an estimate of the return to public investment in crop management research in the Yaqui Valley of Sonora, Mexico;The impact of the crop management research effort is examined by looking at changes in producers\u27 practices 1981-1989 using farm survey data. An examination of changes in producers\u27 practices and modifications in crop management recommendations showed that only two practices were modified because of new research results. The quasi-rent impact of these research-induced changes in farmer practice are estimated using yield function estimation and the construction of enterprise budgets;The market setting for the case study is one of a small producing region facing perfectly elastic demand for output as well as perfectly elastic supply of production inputs. Changes in consumer surplus, therefore, do not occur and the impact on producer surplus is measured as changes in quasi-rent;Estimates of the internal rate of return (IRR) to the crop management research investment are derived under a range of assumptions about the benefit and cost streams. Under the most reasonable sets of assumptions, the IRR is estimated to fall between 16 and 26 percent;The study implies that the development of improved crop management practices can make a significant contribution to increasing agricultural productivity. One implication for the allocation of resources within agronomic research programs is that careful monitoring of farmer acceptance of research results can improve the efficiency of research investments

A Systematic Review of the Critical Factors for Success of Mobile Learning in Higher Education (University Students\u27 Perspective)

The phenomenon of the use of a mobile learning (m-Learning) platform in educational institutions is slowly gaining momentum. However, the enthusiasm with which mobile phones have been welcomed into every aspect of our lives is not yet apparent in the educational sector. To understand the reason, it is important to understand user expectations of the system. This article documents a systematic review of existing studies to find the success factors for effective m-Learning. Our systematic review collates results from 30 studies conducted in 17 countries, where 13 critical success factors were found to strongly impact m-Learning implementation. Using these results within the framework of the diffusion of innovation model for innovation adoption and the critical success factors together help us see what aspects of the innovation decision process are the likely causes of the reduced take-up of m-Learning by university students

Functional Projections of Predicates: Experimental Evidence from Coordinate Structure Processing

This paper reports the results of six experiments involving an on-line self-paced reading task that examine the processing of coordinate small clause predicate phrases versus coordinated arguments NPs. The results have particular significance for the analysis of small clause complement constructions, and support accounts wherein the small clause complement has an Agr projection associated with it. An adequate explanation of the processing of small clause coordination is shown to motivate a new parsing principle, Coordination Feature-matching, which accounts for the longer reading times observed for the coordination of predicates in small clause complements

Flexible predictions during listening comprehension: Speaker reliability affects anticipatory processes

Available online 9 October 2019During listening comprehension, the identification of individual words can be strongly influenced by properties of the preceding context. While sentence context can facilitate both behavioral and neural responses, it is unclear whether these effects can be attributed to the pre-activation of lexico-semantic features or the facilitated integration of contextually congruent words. Moreover, little is known about how statistics of the broader language environment, or information about the current speaker, might shape these facilitation effects. In the present study, we measured neural responses to predictable and unpredictable words as participants listened to sentences for comprehension. Critically, we manipulated the reliability of each speaker’s utterances, such that individual speakers either tended to complete sentences with words that were highly predictable (reliable speaker) or with words that were unpredictable but still plausible (unreliable speaker). As expected, the amplitude of the N400 was reduced for locally predictable words, but, critically, these context effects were also modulated by speaker identity. Sentences from a reliable speaker showed larger facilitation effects with an earlier onset, suggesting that listeners engaged in enhanced anticipatory processing when a speaker’s behavior was more predictable. This finding suggests that listeners can implicitly track the reliability of predictive cues in their environment and use these statistics to adaptively regulate predictive processing.This research was partially funded by NSF (1024003) and NIH (R21 11601946)

Lower Bounds for the Graph Homomorphism Problem

The graph homomorphism problem (HOM) asks whether the vertices of a given $n$-vertex graph $G$ can be mapped to the vertices of a given $h$-vertex graph $H$ such that each edge of $G$ is mapped to an edge of $H$. The problem generalizes the graph coloring problem and at the same time can be viewed as a special case of the $2$-CSP problem. In this paper, we prove several lower bound for HOM under the Exponential Time Hypothesis (ETH) assumption. The main result is a lower bound $2^{\Omega\left( \frac{n \log h}{\log \log h}\right)}$. This rules out the existence of a single-exponential algorithm and shows that the trivial upper bound $2^{{\mathcal O}(n\log{h})}$ is almost asymptotically tight. We also investigate what properties of graphs $G$ and $H$ make it difficult to solve HOM$(G,H)$. An easy observation is that an ${\mathcal O}(h^n)$ upper bound can be improved to ${\mathcal O}(h^{\operatorname{vc}(G)})$ where $\operatorname{vc}(G)$ is the minimum size of a vertex cover of $G$. The second lower bound $h^{\Omega(\operatorname{vc}(G))}$ shows that the upper bound is asymptotically tight. As to the properties of the "right-hand side" graph $H$, it is known that HOM$(G,H)$ can be solved in time $(f(\Delta(H)))^n$ and $(f(\operatorname{tw}(H)))^n$ where $\Delta(H)$ is the maximum degree of $H$ and $\operatorname{tw}(H)$ is the treewidth of $H$. This gives single-exponential algorithms for graphs of bounded maximum degree or bounded treewidth. Since the chromatic number $\chi(H)$ does not exceed $\operatorname{tw}(H)$ and $\Delta(H)+1$, it is natural to ask whether similar upper bounds with respect to $\chi(H)$ can be obtained. We provide a negative answer to this question by establishing a lower bound $(f(\chi(H)))^n$ for any function $f$. We also observe that similar lower bounds can be obtained for locally injective homomorphisms.Comment: 19 page

Acridine functionalized covalent organic frameworks (COFs) as photocatalysts for metallaphotocatalytic C–N cross-coupling

Covalent organic frameworks (COFs) are structurally tuneable, porous and crystalline polymers constructed through the covalent attachment of small organic building blocks as elementary units. Using the myriad of such building blocks, a broad spectrum of functionalities has been applied for COF syntheses for broad applications, including heterogeneous catalysis. Herein, we report the synthesis of a new family of porous and crystalline COFs using a novel acridine linker and benzene-1,3,5-tricarbaldehyde derivatives bearing a variable number of hydroxy groups. With the broad absorption in the visible light region the COFs were applied as photocatalysts in metallaphotocatalytic C–N cross coupling. The fully β-ketoenamine linked COF showed the highest activity, due to the increased charge separation upon irradiation. The COF showed good to excellent yields for several aryl bromides, good recyclability and even catalysed the organic transformation in presence of green light as energy source