Signatures of electronic polarons in La1−x_{1-x}Sr1+x_{1+x}MnO4_4 observed by electron energy-loss spectroscopy

The dielectric properties of La$_{1-x}$Sr$_{1+x}$MnO$_4$ single crystals with x = 0, 0.125, 0.25, and 0.5 were studied by means of electron energy-loss spectroscopy as a function of temperature and momentum transfer. A clear signature of the doped holes is observed around 1.65 eV energy loss, where spectral weight emerges with increasing x. For all $x \neq 0$, this doping-induced excitation can propagate within the ab-plane, as revealed by a clear upward dispersion of the corresponding loss peak with increasing momentum transfer. The hole-induced excitation also shifts to higher energies with the onset of magnetic correlations for x = 0.5, implying a strong coupling of charge and spin dynamics. We conclude that (i) the loss feature at 1.65 eV is a signature of electronic polarons, which are created around doped holes, and that (ii) this low-energy excitation involves the charge transfer between manganese and oxygen. The finite dispersion of these excitations further indicates significant polaron-polaron interactions.Comment: 7 pages, 4 figure

Incense and ritual plant use in Southwest China: A case study among the Bai in Shaxi

ABSTRACT: BACKGROUND: Ritual and religious uses of plant-derived smoke are widespread throughout the world. Our research focuses on Southwest China, where the use of incense is very common. This study aims to document and analyze contemporary ritual plant uses by the Bai people of Shaxi Township (Jianchuan County, Dali Prefecture, Yunnan Province), including their related ethnobotanical knowledge, practices, and beliefs. METHODS: The present study builds on previous ethnobotanical research in Shaxi, which started in 2005. Interviews focusing on ritual plant use and associated beliefs were carried out with a total of 44 Bai informants in September 2009 and May and June 2010. The results are supplemented with information on the local religion collected from June to December 2010. All documented species were vouchered, and are deposited at the herbaria of Kunming Institute of Botany (KUN) and the University of Zurich (Z/ZT). RESULTS: A total of 17 species have been documented for use in incense. They are always used in mixtures and are either burned in the form of powders in a censer or as joss sticks. The smell of the smoke is the main criterion for the selection of the incense plants. Incense is burned for communication with spiritual entities at graves, temples, and cooking stoves, as well as for personal well-being. Cupressus funebris Endl., Gaultheria fragrantissima Wall., and Ligustrum sempervirens (Franch.) Lingelsh. are the most important incense species. Others serve as substitutes or are used to stretch incense powders. CONCLUSIONS: In Shaxi the use of incense mixtures at the household and community level is regularly practiced for communication with ancestors, ghosts, and deities and in some cases to strengthen self-awareness. Some of the documented species are widely used in central Asia and Europe, hinting at the well documented knowledge exchange that occurred in Shaxi, which was a major hub along the influential Southern Silk Road

Money Flows: What Is Holding Back Investment In Agroecological Research For Africa?

The rapidly evolving threats to food and farming systems — from climate shocks to pest stresses — make it more crucial than ever to ensure a continuous flow of knowledge and innovation. Agricultural research for development (AgR4D) is particularly important in sub-Saharan Africa, where climate threats are immediate and food insecurity remains high. With unsustainable forms of intensification driving negative social and environmental impacts in Africa, and with COVID-19 revealing major vulnerabilities in food supply chains, agroecology is emerging as a viable pathway for building sustainable and resilient food systems. Agroecology combines different plants and animals, and uses natural synergies – not synthetic chemicals – to regenerate soils, fertilize crops, and fight pests. Diversity in the field increases access to fresh and nutritious foods for communities and keeps traditional food cultures alive. Agroecology also improves farmers’ livelihoods through diverse income streams, resilience to shocks, and short supply chains that retain value in the community. In other words, agroecology has the potential to reconcile the economic, environmental and social dimensions of sustainability

Traditional herbal medicine in Mesoamerica: toward its evidence base for improving universal health coverage

The quality of health care in Mesoamerica is influenced by its rich cultural diversity and characterized by social inequalities. Especially indigenous and rural communities confront diverse barriers to accessing formal health services, leading to often conflicting plurimedical systems. Fostering integrative medicine is a fundamental pillar for achieving universal health coverage (UHC) for marginalized populations. Recent developments toward health sovereignty in the region are concerned with assessing the role of traditional medicines, and particularly herbal medicines, to foster accessible and culturally pertinent healthcare provision models. In Mesoamerica, as in most regions of the world, a wealth of information on traditional and complementary medicine has been recorded. Yet these data are often scattered, making it difficult for policy makers to regulate and integrate traditionally used botanical products into primary health care. This critical review is based on a quantitative analysis of 28 survey papers focusing on the traditional use of botanical drugs in Mesoamerica used for the compilation of the "Mesoamerican Medicinal Plant Database" (MAMPDB), which includes a total of 12,537 use-records for 2188 plant taxa. Our approach presents a fundamental step toward UHC by presenting a pharmacological and toxicological review of the cross-culturally salient plant taxa and associated botanical drugs used in traditional medicine in Mesoamerica. Especially for native herbal drugs, data about safety and effectiveness are limited. Commonly used cross-culturally salient botanical drugs, which are considered safe but for which data on effectiveness is lacking constitute ideal candidates for treatment outcome studies

Measuring agroecology:Introducing a methodological framework and a community of practice approach

Over the last few years, a small but increasing number of researchers and organizations has been involved in tracking funding flows to agroecology, analyzing development assistance, climate finance, and research funds for their contribution to an agroecological transformation of food systems, including as part of the efforts to achieve the Sustainable Development Goals. This has led to the emergence of a community of practice (CoP) meeting and exchanging in a number of different forums—Financing Agroecology Civil Society CoP, the Agroecology Donor Group, and the Working Group on Financing and Investments of the Coalition for Food Systems Transformation Through Agroecology (Agroecology Coalition). In this article, we report on a process of collaboratively developing a methodological framework, using the High Level Panel of Experts of the Committee on World Food Security 13 principles of agroecology as foundation. This framework overcomes some limitations of previous methodologies for evaluating degrees of agroecological integration (including those using Gliessman’s 5 levels of food system change) and facilitates a robust qualitative assessment of projects, programs, and project portfolios with respect to their “agroecologicalness.” The framework conceives of agroecology as paradigm-shifting rather than as incremental improvements to existing food systems. It enables global comparability as well as local contextualization of each principle. While the need for this framework arose from the desire to monitor—and increase—financial support for an urgently needed transformation toward agroecology, the framework can equally contribute to the design of projects and programs, which aim to radically transform food and farming systems. It also has value as an educational tool, in specifying through statements of value and concrete examples, what agroecological work aims at. This article introduces our framework and argues for an expanded CoP approach to use it widely and share the results through the digital platform that will be developed for that purpose

The measure of agroecology: Developing an assessment framework to capture economic, environmental and social impacts of agriculture and food systems

A key objective of the CGIAR Agroecology Initiative is to develop a holistic assessment framework that generates evidence on the performance of food systems across various dimensions and scales of agroecological transition. Although many tools have been developed to assess the sustainability of agricultural systems, most do not comprehensively represent environmental, social, and economic aspects of sustainability, nor use indicators that are sensitive to agroecological principles. Assessment frameworks also struggle to balance the trade-off between capturing standardized, globally comparable metrics or capturing metrics that are locally relevant and context-specific. These factors make it challenging to assess the multi-functional and multidimensional performance of AE across food systems in diverse contexts. This is particularly true for frameworks developed in the Global North, which may not be applicable to the conditions present in the Global South. Therefore, there is a critical need for an AE-specific assessment framework that not only integrates key features of AE, but also encompasses the salient features of local AE endeavors