scholarly journals Groundwater Protection Policy and Agricultural Production: A Recursive Stochastic Analysis

1988 ◽  
Vol 17 (2) ◽  
pp. 131-138 ◽  
Author(s):  
Brian P. Baker

Contamination of groundwater by agricultural practices presents a dilemma between protecting a vital resource and maintaining a valuable part of the economy. Policies to balance these objectives are presented. In addition to an historical baseline, policies that ban certain pesticides, taxes and subsidies, and control cultural practices are also considered. A model is developed to reflect the current state of agriculture in Eastern Suffolk County. This model consists of a recursive programming component, which has input for it generated by a stochastic model of Colorado potato beetle pest dynamics and management strategies to control those pests. While income is reduced by banning pesticides, the reduction is small when compared with the improvement in environmental quality. Further efforts to reduce pesticide use resulted in a reduction in potato acreage and incomes, as well as yields. Analysis concludes that improvements in both farm income and environmental quality could be achieved through the adoption of subsidies for low-input conservation crops.

2018 ◽  
Vol 11 (2) ◽  
pp. 114-130
Author(s):  
Pavithra Nagarajan

This article explores how a single-sex school for boys of color intentionally and unintentionally (re)defines masculinity through rules and rituals. The school’s mission posits that boys become men through developing three skills: selfregulation, self-awareness, and self-reflection. Drawing from qualitative research data, I examine how disciplinary practices prioritize boys’ ability to control their bodies and image, or “self-regulate.” When boys fail to self-regulate, they enter the punitive system. School staff describe self-regulation as integral to out-of-school success, but these practices may inadvertently reproduce negative labeling and control of black bodies. This article argues for school cultural practices that affirm, rather than deny, the benefits of boyhood.


2019 ◽  
pp. 37-47
Author(s):  
Yao Yueqin ◽  
Oleksiy Kozlov ◽  
Oleksandr Gerasin ◽  
Galyna Kondratenko

Analysis and formalization of the monitoring and automatic control tasks of the MR for the movement and execution of various types of technological operations on inclined and vertical ferromagnetic surfaces are obtained. Generalized structure of mobile robotic complex is shown with main subsystems consideration. Critical analysis of the current state of the problem of development of universal structures of mobile robots (MRs) for the various types of technological operations execution and elaborations of computerized systems for monitoring and control of MR movement is done. In particular, wheeled, walked and crawler type MRs with pneumatic, vacuum-propeller, magnetic and magnetically operated clamping devices to grip with vertical and ceiling surfaces are reviewed. The constructive features of the crawler MR with magnetic clamping devices capable of moving along sloping ferromagnetic surfaces are considered. The basic technical parameters of the MR are shown for the further synthesis of computerized monitoring and automatic control systems. Formalization of the tasks of monitoring and control of the MR positioning at the processing of large area ferromagnetic surfaces is considered from the point of view of control theory.


2020 ◽  
Vol 04 ◽  
Author(s):  
A. Guillermo Bracamonte

: Graphene as Organic material showed special attention due to their electronic and conductive properties. Moreover, its highly conjugated chemical structures and relative easy modification permitted varied design and control of targeted properties and applications. In addition, this Nanomaterial accompanied with pseudo Electromagnetic fields permitted photonics, electronics and Quantum interactions with their surrounding that generated new materials properties. In this context, this short Review, intends to discuss many of these studies related with new materials based on graphene for light and electronic interactions, conductions, and new modes of non-classical light generation. It should be highlighted that these new materials and metamaterials are currently in progress. For this reason it was showed and discussed some representative examples from Fundamental Research with Potential Applications as well as for their incorporations to real Advanced devices and miniaturized instrumentation. In this way, it was proposed this Special issue entitled “Design and synthesis of Hybrids Graphene based Metamaterials”, in order to open and share the knowledge of the Current State of the Art in this Multidisciplinary field.


Soil Systems ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 32
Author(s):  
Haddish Melakeberhan ◽  
Gregory Bonito ◽  
Alexandra N. Kravchenko

Soil health connotes the balance of biological, physicochemical, nutritional, structural, and water-holding components necessary to sustain plant productivity. Despite a substantial knowledge base, achieving sustainable soil health remains a goal because it is difficult to simultaneously: (i) improve soil structure, physicochemistry, water-holding capacity, and nutrient cycling; (ii) suppress pests and diseases while increasing beneficial organisms; and (iii) improve biological functioning leading to improved biomass/crop yield. The objectives of this review are (a) to identify agricultural practices (APs) driving soil health degradations and barriers to developing sustainable soil health, and (b) to describe how the nematode community analyses-based soil food web (SFW) and fertilizer use efficiency (FUE) data visualization models can be used towards developing sustainable soil health. The SFW model considers changes in beneficial nematode population dynamics relative to food and reproduction (enrichment index, EI; y-axis) and resistance to disturbance (structure index, SI; x-axis) in order to identify best-to-worst case scenarios for nutrient cycling and agroecosystem suitability of AP-driven outcomes. The FUE model visualizes associations between beneficial and plant-parasitic nematodes (x-axis) and ecosystem services (e.g., yield or nutrients, y-axis). The x-y relationship identifies best-to-worst case scenarios of the outcomes for sustainability. Both models can serve as platforms towards developing integrated and sustainable soil health management strategies on a location-specific or a one-size-fits-all basis. Future improvements for increased implementation of these models are discussed.


Author(s):  
Dung Le ◽  
Kris Audenaert ◽  
Geert Haesaert

AbstractFusarium basal rot (FBR) is a soil-borne disease that affects Allium species worldwide. Although FBR has long been recognized as a major constraint to the production of economically important Allium species, information that could support disease management remains scattered. In this review, the current knowledge on the causal agents, symptomology and epidemiology, impact, and management strategies of FBR is synthesized. We highlight that FPR is associated with different complexes of several Fusarium species, of which Fusarium oxysporum and F. proliferatum are the most prevalent. These pathogenic complexes vary in composition and virulence, depending on sites and hosts, which can be challenging for disease management. Research to improve disease management using chemical pesticides, resistance cultivars, biocontrol agents, and cultural practices has achieved both promising results and limitations. Finally, research needs and future directions are proposed for the development of effective FBR management strategies.


Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 320
Author(s):  
Alexander Nilon ◽  
Karl Robinson ◽  
Hanu R. Pappu ◽  
Neena Mitter

Tomato spotted wilt virus (TSWV) is the type member of the genus Orthotospovirus in the family Tospoviridae and order Bunyavirales. TSWV, transmitted by several species of thrips, causes significant disease losses to agronomic and horticultural crops worldwide, impacting both the yield and quality of the produce. Management strategies include growing virus-resistant cultivars, cultural practices, and managing thrips vectors through pesticide application. However, numerous studies have reported that TSWV isolates can overcome host-plant resistance, while thrips are developing resistance to pesticides that were once effective. RNA interference (RNAi) offers a means of host defence by using double-stranded (ds) RNA to initiate gene silencing against invading viruses. However, adoption of this approach requires production and use of transgenic plants and thus limits the practical application of RNAi against TSWV and other viruses. To fully utilize the potential of RNAi for virus management at the field level, new and novel approaches are needed. In this review, we summarize RNAi and highlight the potential of topical or exogenous application of RNAi triggers for managing TSWV and thrips vectors.


1995 ◽  
Vol 117 (B) ◽  
pp. 80-86 ◽  
Author(s):  
Lung-Wen Tsai

This paper presents an overview of the current state-of-the-art in the design of tendon-driven manipulators. A special characteristic associated with tendon-driven manipulators is that tendons can only exert tension but not compression. Based on this unique characteristic, the fundamental mechanics associated with the design of tendon-driven manipulators are reviewed. The review includes structure classification, kinematics, statics, dynamics and control.


2020 ◽  
Author(s):  
John Onditi ◽  
Nancy Ng’anga ◽  
Moses Nyongesa ◽  
René van der Vlugt

AbstractPotato is an important food security crop in Kenya. High prevalence of potato viruses is one of the major causes of low potato yields. Implementation of effective virus management strategies requires information on farmers’ perceptions and practices on virus epidemiology and control. To better understand farmers’ knowledge and practices in virus control and set possible pathways for intervention, a household survey involving 147 respondents was conducted in two major potato-growing regions in Kenya. Lack of sufficient technical information on potato virus symptoms, vectors and modes of transmission was found to be the major hindrance to farmers’ efforts towards virus control. A spider diagram approach was therefore used to determine the aspect of virus control that required the highest prioritization for immediate intervention by policy makers. Use of virus-resistant cultivars was found to require the most urgent attention compared to other aspects of virus control and was expected to have greater impact in lowering virus prevalence. This study showed that enhancing farmer knowledge needs to be prioritised as this is a key determinant of the success of the virus control strategy to be selected for implementation.


Sign in / Sign up

Export Citation Format

Share Document