860 research outputs found
Submission for Koronivia joint work on agriculture (KJWA) on topics 2(b) and 2(c) for SBI/SBSTA 50
Background
At this Koronivia joint work on agriculture (KJWA) in-session workshop in Bonn (SBI/SBSTA 50), adaptation, adaptation co-benefits and resilience (2(b)), as well as the role of soils and integrated agricultural systems in particular (2(c)), will be at the centre of discussions.
This submission provides first insights on these topics based on an ongoing scientific review of the empirical evidence for agroecology to tackle climate change in agriculture. The rationale for this review is the need for increased evidence on agroecology’s potential to build resilience to climate change. Its objective is therefore to assess the state of scientific knowledge on this question. Agroecological agricultural systems, for short, are characterised by following and combining priciples such as closed nutrient cycles, increasing soil fertility and diversity as well as building on natural ecosystem processes and services (e.g. for plant protection). Some examples of agroecological practices are organic fertilisers (compost), biological nitrogen fixation, crop rotations, cover crops, agroforestry, or mixed crop and livestock farms. Agroecology also emphasizes social aspects, focusing on e.g. equity issues, collaborative development, farmers to farmers research and education, and bottom-up organisations of value chains.
The still ongoing review is conducted in a collaborative effort by Biovision Foundation for ecological development, the Research Institute of Organic Agriculture FiBL and the Food and Agriculture Organization of the United Nations FAO. It is based on an encompassing compilation of peer-reviewed literature published in English (number of studies identified: 193), Spanish (23), French (35), Portuguese (3) and Italian (4). The requirement for comparative studies, i.e. to provide data on both agroecological and some baseline farming system restricted the available studies considerably. This review is complemented with results from meta-analyses on the performance of specific agro-ecological practices and related approaches, such as conservation tillage, permaculture, organic agriculture or silvopastoral systems. The full review is planned to be be published for COP25
Assessment of key factors responsible for the pest status of the bean flower thrips Megalurothrips sjostedti (Thysanoptera: Thripidae) in West Africa
Megalurothrips sjostedti (Trybom) is an important pest of cowpea (Vigna unguiculata) in West Africa. Three key factors assumed to be responsible for its pest status are analysed, the survival on alternative host-plants during the dry season, the inefficient biotic mortality factors regulating population growth, and the effect of larval feeding on the development of cowpea flower buds. Extensive surveys indicate clearly that M. sjostedti survives the dry season on a wide range of alternative hosts all belonging to the Leguminosae, where it can feed and reproduce. Different antagonists were observed attacking eggs and larvae of M. sjostedti; their impact, however, is low and cannot prevent pest outbreaks. Two undescribed Megaphragma spp., and one Oligosita sp., all trichogrammatid egg parasitoids, were recorded for the first time. The anthocorid Orius sp. was the most important larval predator. No hymenopterous parasitoids could be reared from larvae collected on cowpea and three major alternative hosts, whereas a low percentage of the larvae collected from the flowers of Tephrosia candida, an exotic shrub native to India, were parasitized by the eulophid Ceranisus menes (Walker), also recorded for the first time in Africa. The feeding activity of six larvae of Megalurothrips sjostedti during five days induced the shedding of all flower buds of a cowpea inflorescence. The results of the analysis shed new light on the M. sjostedti pest problem, and the ways to solve it. The lack of efficient antagonists, particularly larval parasitoids known from closely related south-east Asian Megalurothrips spp., and the high damage threshold, indicate that M. sjostedti is a potential target for biological control. However, further studies are needed to investigate the migration of M. sjostedti adults to and from alternative host-plants, in order to reinforce the action of biocontrol with cultural pratice
Rapid Microwave Polymerization of Porous Nanocomposites with Piezoresistive Sensing Function
In this paper, polydimethylsiloxane (PDMS) and multi-walled carbon nanotube (MWCNT) nanocomposites with piezoresistive sensing function were fabricated using microwave irradiation. The effects of precuring time on the mechanical and electrical properties of nanocomposites were investigated. The increased viscosity and possible nanofiller re-agglomeration during the precuring process caused decreased microwave absorption, resulting in extended curing times, and decreased porosity and electrical conductivity in the cured nanocomposites. The porosity generated during the microwave-curing process was investigated with a scanning electron microscope (SEM) and density measurements. Increased loadings of MWCNTs resulted in shortened curing times and an increased number of small well-dispersed closed-cell pores. The mechanical properties of the synthesized nanocomposites including stress–strain behaviors and Young’s Modulus were examined. Experimental results demonstrated that the synthesized nanocomposites with 2.5 wt. % MWCNTs achieved the highest piezoresistive sensitivity with an average gauge factor of 7.9 at 10% applied strain. The piezoresistive responses of these nanocomposites were characterized under compressive loads at various maximum strains, loading rates, and under viscoelastic stress relaxation conditions. The 2.5 wt. % nanocomposite was successfully used in an application as a skin-attachable compression sensor for human motion detection including squeezing a golf ball.This research received no external funding and The APC was funded by University Libraries Open
Access fund. Open Access fees paid for in whole or in part by the University of Oklahoma Libraries.Ye
Developing strategies to capture value from emerging technologies
Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2004.Includes bibliographical references (p. 100-101).The development of fundamentally new technology requires companies to carefully consider how they intend to profit from the commercialization of their ideas. Because companies pursuing disruptive innovations require new organizational capabilities and are often pushing into new markets with unproven technology, they must become masters in dealing with uncertainty. This thesis attempts to provide a holistic and rigorous process to systematically develop and evaluate options for profiting from the commercialization of disruptive technologies that are currently in the limited application stage of development. This thesis reviews the basic elements of technology commercialization, existing approaches to the value capture phase of technology strategy, the fundamental stages of the product development process, and the role of real options theory in addressing uncertainty. The author's experiences with the hydrogen industry provided further insight into the key difficulties in developing strategic options to capture value from the commercialization of disruptive technology. These difficulties include market and technical uncertainty, the infancy of the value chain, capabilities development, the development and valuation of specific strategic options, and the role of established processes, structure and culture of existing companies. This thesis describes a two part process to addressing these difficulties. The macro level process guides the company's strategy development process by emphasizing emergent strategy, the transition to complementary assets, and a focus on navigating the limited application phase of technology commercialization. The product specific strategy provides a rigorous process for exploring the value chain(cont.) identifying sources of uncertainty, and developing specific options for capturing value from the disruptive innovation while emphasizing sound product development practices and requirements. This thesis builds upon the author's experiences at ChevronTexaco to illustrate the application of these concepts. In one case study, the product specific process is applied to the development of a stationary engine emissions control device. The application of this process revealed or verified significant product development risks while emphasizing that the target segment of the value chain was unlikely to be highly profitable. In another case study, a real options analysis is performed to examine the value of ChevronTexaco developing a near term limited manufacturing capability that would provide future strategic flexibility. The analysis demonstrated how an internal manufacturing capability might improve the probability of profiting from the commercialization of hydrogen fuel processing technology.by Steven M. Herren.S.M.M.B.A
Unexpected diversity of Wolbachia associated with Bactrocera dorsalis (Diptera: Tephritidae) in Africa
Bactrocera dorsalis (Hendel) is an important pest of fruit-bearing plants in many countries worldwide. In Africa, this pest has spread rapidly and has become widely established since the first invasion report in 2003. Wolbachia is a vertically transmitted endosymbiont that can significantly influence aspects of the biology and, in particular, the reproduction of its host. In this study, we screened B. dorsalis specimens collected from several locations in Africa between 2005 and 2017 for Wolbachia using a PCR-based assay to target the Wolbachia surface protein wsp. Of the 357 individuals tested, 10 were positive for Wolbachia using the wsp assay. We identified four strains of Wolbachia infecting two B. dorsalis mitochondrial haplotypes. We found no strict association between the infecting strain and host haplotype, with one strain being present in two different host haplotypes. All the detected strains belonged to Super Group B Wolbachia and did not match any strains reported previously in B. dorsalis in Asia. These findings indicate that diverse Wolbachia infections are present in invasive populations of B. dorsalis
Midge-stabilized sediment drives the composition of benthic cladoceran communities in Lake Mývatn, Iceland
The importance of environmental disturbances as drivers of ecological communities depends not only on the magnitude of the disturbance, but also on the disturbance-specific sensitivity of the community. Organisms that alter the physical structure of their surroundings can affect the sensitivity of their habitat to environmental disturbance, and may alter the potential for disturbance to shape ecological communities. Such organisms therefore act as ecosystem engineers by indirectly modifying the resources available to other species. The benthos of shallow, eutrophic Lake Mývatn, Iceland, is frequently disturbed by wind events that lead to sediment resuspension. The impact of wind, however, depends on the abundance of midges (Chironomidae) whose larval tubes bind sediment and reduce wind-driven resuspension. Here, we investigate the long-term effect of fluctuations in midge abundance on the benthic cladoceran community using two lake sediment cores representing 30 and 140 years of deposition. In both cores, midge remains show a significant positive correlation with abundance of a large benthic surface-dwelling cladoceran, Eurycercus lamellatus, relative to the abundance of a small within-sediment-dwelling cladoceran, Alona rectangula. To experimentally investigate whether this shift could have been caused by midges acting as ecosystem engineers, we subjected cladoceran communities to sediment resuspension events within mesocosms. We found a significant decrease in abundance of the large epibenthic E. lamellatus relative to the abundance of small infaunal Alona spp. when subjected to disturbance. These findings show that physical alteration of benthic sediment and hence the sensitivity of the sediment to disturbance may explain the community shift in cladocerans observed with fluctuating midge abundance in Lake Mývatn.National Science Foundation Graduate Research Fellowship. Grant Number: DGE-1256259
LTREB. Grant Number: DEB-1052160Peer Reviewe
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