314,818 research outputs found

    Genomics and breeding innovations for enhancing genetic gain for climate resilience and nutrition traits

    Get PDF
    Accelerating genetic gain in crop improvement programs with respect to climate resilience and nutrition traits, and the realization of the improved gain in farmers’ fields require integration of several approaches. This article focuses on innovative approaches to address core components of the breeder’s equation. A prerequisite to enhancing genetic variance (σ2g) is the identification or creation of favorable alleles/haplotypes and their deployment for improving key traits. Novel alleles for new and existing target traits need to be accessed and added to the breeding population while maintaining genetic diversity. Selection intensity (i) in the breeding program can be improved by testing a larger population size, enabled by the statistical designs with minimal replications and high-throughput phenotyping. Selection priorities and criteria to select appropriate portion of the population too assume an important role. The most important component of breeder′s equation is heritability (h2). Heritability estimates depend on several factors including the size and the type of population and the statistical methods. The present article starts with a brief discussion on the potential ways to enhance σ2g in the population. We highlight statistical methods and experimental designs that could improve trait heritability estimation. We also offer a perspective on reducing the breeding cycle time (t), which could be achieved through the selection of appropriate parents, optimizing the breeding scheme, rapid fixation of target alleles, and combining speed breeding with breeding programs to optimize trials for release. Finally, we summarize knowledge from multiple disciplines for enhancing genetic gains for climate resilience and nutritional traits

    The Ecosystem Approach to Fisheries: Issues, Terminology, Principles, Institutional Foundations, Implementation and Outlook

    Get PDF
    Ecosystems are complex and dynamic natural units that produce goods and services beyond those of benefit to fisheries. Because fisheries have a direct impact on the ecosystem, which is also impacted by other human activities, they need to be managed in an ecosystem context. The meaning of the terms 'ecosystem management', 'ecosystem based management', 'ecosystem approach to fisheries'(EAF), etc., are still not universally defined and progressively evolving. The justification of EAF is evident in the characteristics of an exploited ecosystem and the impacts resulting from fisheries and other activities. The rich set of international agreements of relevance to EAF contains a large number of principles and conceptual objectives. Both provide a fundamental guidance and a significant challenge for the implementation of EAF. The available international instruments also provide the institutional foundations for EAF. The FAO Code of Conduct for Responsible Fisheries is particularly important in this respect and contains provisions for practically all aspects of the approach. One major difficulty in defining EAF lies precisely in turning the available concepts and principles into operational objectives from which an EAF management plan would more easily be developed. The paper discusses these together with the types of action needed to achieve them. Experience in EAF implementation is still limited but some issues are already apparent, e.g. in added complexity, insufficient capacity, slow implementation, need for a pragmatic approach, etc. It is argued, in conclusion, that the future of EAF and fisheries depends on the way in which the two fundamental concepts of fisheries management and ecosystem management, and their respective stakeholders, will join efforts or collide

    Can forest management based on natural disturbances maintain ecological resilience?

    Get PDF
    Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance

    State-of-the-art in aerodynamic shape optimisation methods

    Get PDF
    Aerodynamic optimisation has become an indispensable component for any aerodynamic design over the past 60 years, with applications to aircraft, cars, trains, bridges, wind turbines, internal pipe flows, and cavities, among others, and is thus relevant in many facets of technology. With advancements in computational power, automated design optimisation procedures have become more competent, however, there is an ambiguity and bias throughout the literature with regards to relative performance of optimisation architectures and employed algorithms. This paper provides a well-balanced critical review of the dominant optimisation approaches that have been integrated with aerodynamic theory for the purpose of shape optimisation. A total of 229 papers, published in more than 120 journals and conference proceedings, have been classified into 6 different optimisation algorithm approaches. The material cited includes some of the most well-established authors and publications in the field of aerodynamic optimisation. This paper aims to eliminate bias toward certain algorithms by analysing the limitations, drawbacks, and the benefits of the most utilised optimisation approaches. This review provides comprehensive but straightforward insight for non-specialists and reference detailing the current state for specialist practitioners

    The Danger of Duality: Medicare and Medicaid as a Double Threat

    Get PDF
    My paper discusses the topic of dual eligible beneficiaries – a group of some nine million individuals that has rightly earned a reputation for being the most costly, frail, sickly, and vulnerable population. Individuals are considered “dual eligible” when they qualify for the benefits of both government programs of Medicare and Medicaid. The main problem within the dual eligible arena is the lack of coordination between these two programs – the federal government wholly funds Medicare but Medicaid is a joint federal-state program that varies from state to state. Because these programs were not designed to work together and sometimes even work at cross-purposes, dual eligible beneficiaries have incurred excessive costs for both the federal and state governments. More importantly, conflicts between the policies of Medicare and Medicaid have led to rather poor quality of care for these needy individuals. Thus far, there have been strides forward in better integrating and coordinating care for dual eligible seen in the Program of the All-Inclusive Care for the Elderly (PACE) and Dual-eligible Special Needs Plans (D-SNPs). The ACA also plans to continue forward in attempts to reduce costs and improve care for dual eligibles. However, evidence from these past, current, and future efforts, indicates significant reform will not be possible until the government implements a mandate for state participation in integrated programs for dual eligible beneficiaries. Without this bold yet necessary move, costs will continue to skyrocket at an unsustainable rate and, worse, these individuals will not see an improvement in the quality of care they receive

    Putting Into Practice the Ecosystem Approach to Fisheries

    Get PDF
    This document is an abridged version of the FAO Fisheries Technical Guidelines No. 4, Suppl. 2, entitled Fisheries management. 2. The ecosystem approach to fisheries. It is intended to provide a more concise and less technical outline of the purpose and meaning of the ecosystem approach to fisheries (EAF) and guidance as to how to implement the approach. Although the principles of an ecosystem approach to fisheries (EAF) are not new, there is very little practical experience in their implementation. Translating high-level policy goals on EAF into operational objectives and actions is now the key challenge to sustainable fisheries.This booklet provides an overview of EAF, for marine capture fisheries, and its benefits. It considers what is required to implement EAF and the range of management measures available. It provides an overview of the management process, outlines any outstanding research requirements, and lists the main threats to the implementation of EAF

    Seed mass diversity along resource gradients: the role of allometric growth rate and size-asymmetric competition

    Full text link
    The large variation in seed mass among species inspired a vast array of theoretical and empirical research attempting to explain this variation. So far, seed mass variation was investigated by two classes of studies: one class focuses on species varying in seed mass within communities, while the second focuses on variation between communities, most often with respect to resource gradients. Here, we develop a model capable of simultaneously explaining variation in seed mass within and between communities. The model describes resource competition (for both soil and light resources) in annual communities and incorporates two fundamental aspects: light asymmetry (higher light acquisition per unit biomass for larger individuals) and growth allometry (negative dependency of relative growth rate on plant biomass). Results show that both factors are critical in determining patterns of seed mass variation. In general, growth allometry increases the reproductive success of small-seeded species while light asymmetry increases the reproductive success of large-seeded species. Increasing availability of soil resources increases light competition, thereby increasing the reproductive success of large-seeded species and ultimately the community (weighted) mean seed mass. An unexpected prediction of the model is that maximum variation in community seed mass (a measure of functional diversity) occurs under intermediate levels of soil resources. Extensions of the model incorporating size-dependent seed survival and disturbance also show patterns consistent with empirical observations. These overall results suggest that the mechanisms captured by the model are important in determining patterns of species and functional diversity
    corecore