Traffic control in coherence-multiplexed networks

Coherence multiplexing (CM) is a relatively unknown form of optical CDMA, which is particulary suitable in medium bit rate, short-range optical networks like LANs. The main purpose of the technique is to allow multiple users to transmit through a common optical fiber simultaneously. When this number is too large, however, the BER will become unacceptably high. Therefore a protocol is needed to control the traffic. In this paper several protocols are presented. An adapted version of synchronous TDMA, two new protocols and a central control unit will be proposed and discussed. Finally, the protocols will be compared with respect to performance and practical implementation aspects

Do equal land and water rights benefit the poor?: Targeted irrigation development: The case of the Andhi Khola Irrigation Scheme in Nepal

Irrigation programs / Water rights / Poverty / Households / Surveys / Water allocation / Water distribution / Water users’ associations / Farmers / Landlessness / Land ownership

Changes to land tenure and pastoral lease ownership in Western Australia\u27s central rangelands: Implications for co-operative, landscape-scale management

The majority of arid and semiarid land in the Western Australian pastoral zone has a long history of livestock grazing within an extensive network of predominantly family-held pastoral leases. A variety of different groups have purchased pastoral leases in the last five decades and, for many, making a profit from pastoralism is no longer a priority. For the central rangelands of Western Australia, these groups have included: government agencies, who have purchased some 9% of pastoral leases by area; private conservation organisations (\u3c1% purchased); aboriginal communities and groups (∼7%); and mining companies (∼13%). The purchases of pastoral leases by government agencies was designed to improve the conservation status of arid-zone ecosystems, and is the first step in a process of changing land tenure to a conservation reserve. This paper summarises the extent and other characteristics of these changes in land tenure and ownership of pastoral leases, and explores the implications for land management and conservation, stemming from these changes. It demonstrates that large areas of contiguous land with no or reduced domestic stocking can now be found in many parts of these rangelands, particularly in the Coolgardie, Yalgoo and Pilbara bio-regions, with some leaseholders actively managing land for the conservation of biodiversity and restoring sites degraded through past over-grazing. In some bio-regions, such land covers considerable proportions of sub-catchments, suggesting that broad-scale conservation management and restoration objectives may be realised. It is argued that to fully realise these objectives requires effective communication and co-ordination between land managers, including sharing of ideas, view-points and resources. In particular, mining companies, now major holders of pastoral leases in Western Australia, can play an important role in contributing to and even facilitating such objectives

Genetic diversity of maize (Zea mays L. ssp. mays) in communities of the western highlands of Guatemala: geographical patterns and processes.

This study concerns spatial genetic patterning, seed flow and the impact of modern varieties in maize populations in Chimaltenango, Guatemala. It uses a collection of 79 maize seed samples from farmers in the area and five samples derived from modern varieties. Bulked SSR markers employed with bulked samples (ten plants) were used. Genetic distances between populations based on these SSR data were used as a measure of co-ancestry. The study describes the genetic variation in space, assesses the association of maize diversity with spatial and environmental descriptors and quantitative traits, and provides a test of the impact of improved varieties. Maize diversity showed significant isolation-by-distance locally, but not regionally. This was interpreted as evidence for a difference between local and regional mechanisms of seed exchange; regional exchange is more related to innovation. There was also a significant association with altitude and ear/grain characteristics (related to racial classifications). Also, consistent evidence for the influence of modern varieties of maize was found, although its impact was limited spatially. It is argued that the spatial distributions of maize diversity are important to consider for germplasm collection, but should be seen as a recent outcome of dynamic processes

Adaptacion climatica mediante ensayos en finca: Evaluacion Participativa Masiva (EPM). Guia metodologica

La Evaluacion Participativa Masiva (EPM) es un nuevo enfoque para evaluar variedades y otras tecnologias agricolas en finca, bajo condiciones representativas. A traves de un proceso de experimentacion sencillo y practico, los agricultores identifican innovaciones que les benefician realmente. EPM es una metodologia completa que sirve tanto para la investigacion como para la distribucion de variedades y otras tecnologias agricolas en areas con condiciones variables. A traves de un esquema de pruebas distribuidas geograficamente, la metodología EPM puede proveer informacion sobre los patrones geograficos en la adaptacion climatica y ayudar a acelerar la identificacion de tecnologias apropiadas localmente para responder al cambio climatico. Provee una forma de conectar el desarrollo de nuevas tecnologias realizado por institutos de investigacion con las experiencias de los agricultores. El proceso de EMP es apoyado por una plataforma digital que se encuentra en www.climmob.net. Esta publicacion provee una descripcion de la metodología con lineamientos para su uso en el campo

Farmer experimentation for climate adaptation with triadic comparisons of technologies (tricot): a methodological guide

Triadic Comparisons of Technologies (tricot), is a new approach to test crop varieties and other technologies on-farm, under realistic conditions. Through simple and hands-on experimentation, the participating farmers identify innovations that will be of real benefit to them. Tricot is a ready-made methodology, serving both research, and the dissemination of varieties and other technologies and practices in highly variable areas. Through geographically distributed testing, tricot is able to provide information about geographic patterns in climate adaptation and help to speed up the identification of locally suitable technologies to respond to climate change. It provides a means to linktechnology development of research institutes to real-life experiences of farmers. It is supported by a digital platform that can be found at www.climmob.net. This publication provides a description of the methodology with guidelines for its implementation in the field

University student volunteering alignment with sustainability principles

This research paper reviews the concept and practice of tertiary sciences students doing environmental volunteering, otherwise known as conservation volunteering, as a core part of their course to check its alignment with sustainability principles. First year Natural Sciences students at Edith Cowan University do five days environmental volunteer work with community groups as practicum. Initial research data displays the number of volunteer hours done by students in various types of activities, locations and organisations. Preliminary quantitative evaluations and qualitative comments demonstrate students’ positive attitudes and outcomes from their volunteering experiences. Definitions and classifications of sustainability from current literature are discussed as part of the curriculum design review process. Initial data from host organisations and students suggests that this environmental volunteering contributes to employability skills, although the program needs to be evaluated as one component of an integrated program of Work-Integrated Learning (WIL) that the students are required to complete. Students learn about potential careers and the environment industry’s reliance on volunteers. Students learn and practise specific skills (e.g. animal handling) and contribute to communities and the environment

Ecological Restoration of Novel Lake Districts: New Approaches for New Landscapes

Mine void pit lakes often contain water of poor quality with potential for environmental harm that may dwarf other mine closure environmental issues in terms of severity, scope, and longevity. This is particularly so when many pit lakes occur close together and thus form a new ‘‘lake district’’ landscape. Pit lakes that can be developed into healthy lake or wetland ecosystems as a beneficial end use provide opportunities for the mining industry to fulfil commitments to sustainability. Clearly articulated restoration goals and a strategic closure plan are necessary to ensure pit lake restoration toward a new, yet regionally-relevant, aquatic ecosystem, which can achieve sustainability as an out-of-kind environmental offset. Such an approach must also consider obstacles to development of a self-sustaining aquatic ecosystem, such as water quality and ecological requirements. We recommend integration of pit lakes into their catchments as a landscape restoration planning exercise with clearly-identified roles and objectives for each new lake habitat and its surrounds

Rings and Jets around PSR J2021+3651: the `Dragonfly Nebula'

We describe recent Chandra ACIS observations of the Vela-like pulsar PSR J2021+3651 and its pulsar wind nebula (PWN). This `Dragonfly Nebula' displays an axisymmetric morphology, with bright inner jets, a double-ridged inner nebula, and a ~30" polar jet. The PWN is embedded in faint diffuse emission: a bow shock-like structure with standoff ~1' brackets the pulsar to the east and emission trails off westward for 3-4'. Thermal (kT=0.16 +/-0.02 keV) and power law emission are detected from the pulsar. The nebular X-rays show spectral steepening from Gamma=1.5 in the equatorial torus to Gamma=1.9 in the outer nebula, suggesting synchrotron burn-off. A fit to the `Dragonfly' structure suggests a large (86 +/-1 degree) inclination with a double equatorial torus. Vela is currently the only other PWN showing such double structure. The >12 kpc distance implied by the pulsar dispersion measure is not supported by the X-ray data; spectral, scale and efficiency arguments suggest a more modest 3-4 kpc.Comment: 22 pages, 5 figures, 3 tables, Accepted to Ap

The accuracy of farmer-generated data in an agricultural citizen science methodology.

Over the last decades, participatory approaches involving on-farm experimentation have become more prevalent in agricultural research. Nevertheless, these approaches remain difficult to scale because they usually require close attention from well-trained professionals. Novel large-N participatory trials, building on recent advances in citizen science and crowdsourcing methodologies, involve large numbers of participants and little researcher supervision. Reduced supervision may affect data quality, but the “Wisdom of Crowds” principle implies that many independent observations from a diverse group of people often lead to highly accurate results when taken together. In this study, we test whether farmer-generated data in agricultural citizen science are good enough to generate valid statements about the research topic. We experimentally assess the accuracy of farmer observations in trials of crowdsourced crop variety selection that use triadic comparisons of technologies (tricot). At five sites in Honduras, 35 farmers (women and men) participated in tricot experiments. They ranked three varieties of common bean (Phaseolus vulgaris L.) for Plant vigor, Plant architecture, Pest resistance, and Disease resistance. Furthermore, with a simulation approach using the empirical data, we did an order-of-magnitude estimation of the sample size of participants needed to produce relevant results. Reliability of farmers’ experimental observations was generally low (Kendall’s W0.174 to 0.676). But aggregated observations contained information and had sufficient validity (Kendall’s tau coefficient 0.33 to 0.76) to identify the correct ranking orders of varieties by fitting Mallows-Bradley-Terry models to the data. Our sample size simulation shows that low reliability can be compensated by engaging higher numbers of observers to generate statistically meaningful results, demonstrating the usefulness of the Wisdom of Crowds principle in agricultural research. In this first study on data quality from a farmer citizen science methodology, we show that realistic numbers of less than 200 participants can produce meaningful results for agricultural research by tricot-style trials