136 research outputs found

    Linear Protection Schemes Analysis in Scattered Placement Fiber-To-The Home-Passive Optical Network Using Customer Access Protection Unit Solution

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    <STRONG>Problem statement:</STRONG> This study highlights on restoration scheme proposed against failure in working line at the drop region for Fiber-To-The Home (FTTH) with a Passive Optical Network (PON). Whereas PON is a system that brings optical fiber cable and signals all or most of the way to the end user.<STRONG> Approach:</STRONG> Survivability scheme against failure is focused on scattered residence architectures and it is applied in the ring and tree topology respectively by means of Customer Access Protection Unit (CAPU). CAPU will be installed before the ONU and ensure the signal will find the alternative path when failure occurs at the specific line. Our proposal scheme is low cost and applicable to any residence architecture. The advantage of this scheme is the failure at fiber line can be recovered until three levels to make sure the optic signal flow continuously to avoid any application disturbance. Two type of restoration scheme is proposed by means of linear protection (tree) and migrated protection (ring). FTTH based network design is simulated by using Opti System 7.0 in order to investigate the power output and BER performance at each node in the tree and ring protection scheme in scattered placement. This study we perform an analysis on linear protection scheme that consisting of two model a) Line to Line (L2L) protection and CAPU to CAPU (C2C) or Shared protection. However the migration of tree to ring topology to enable the signal flow continuously in the case of failure occurs specifically in random or scattered placement topology has been highlighted in our previous publication. <STRONG>Results:</STRONG> The signal will be divided into section; drop and pass through and the ratio is significant to determine the number of user allowed and achievable distance. Output power for optical nodes could be slightly improved by varying the pass through and drop signal ratio. <STRONG>Conclusion:</STRONG> Our proposal is the first reported up to this time in which the upstream signal flows in anticlockwise in ring topology when the restoration scheme activated

    The Nihoku Ecosystem Restoration Project: A case study in predator exclusion fencing, ecosystem restoration, and seabird translocation

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    Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.Newell’s Shearwater (Puffinus auricularis newelli; NESH) and Hawaiian Petrel (Pterodroma sandwichensis; HAPE) are both listed under the Endangered Species Act of 1973 and are declining due to collisions with power lines and structures, light attraction, predation by feral cats, pigs, rats, and introduced Barn Owls, habitat degradation by feral ungulates (pigs, goats) and invasive exotic plants. Protection of NESH and HAPE on their nesting grounds and reduction of collision and lighting hazards are high priority recovery actions for these species. Given the challenges in protecting nesting birds in their rugged montane habitats, it has long been desirable to also create breeding colonies of both species in more accessible locations that offer a higher level of protection. Translocation of birds to breeding sites within predator exclusion fences was ranked as priority 1 in the interagency 5-year Action Plan for Newell’s Shearwater and Hawaiian Petrel. In 2012, funding became available through several programs to undertake this action at Kilauea Point National Wildlife Refuge (KPNWR), which is home to one of the largest seabird colonies in the main Hawaiian Islands. The project was named the “Nihoku Ecosystem Restoration Project” after the area on the Refuge where the placement of the future colony was planned. The Nihoku Ecosystem Restoration Project is a result of a large partnership between multiple government agencies and non-profit groups who have come together to help preserve the native species of Hawaii. There were four stages to this multi-faceted project: permitting and biological monitoring, fence construction, restoration and predator eradication, followed by translocation of the birds to the newly secured habitat. The translocation component is expected to last five years and involve up to 90 individuals each of NESH and HAPE. Prior to fence construction, baseline monitoring data were collected in order to provide a record of initial site conditions and species diversity. Surveys were conducted quarterly from 2012-2014, investigating diversity and richness of plant, invertebrate, mammalian, and avian species. A 650 m (2130 ft) long predator proof fence was completed at Nihoku in September 2014, enclosing 2.5 ha (6.2 ac), and all mammalian predators were eradicated by March 2015. From 2015-2017, approximately 40% of the fenced area (~1 ha) was cleared of non-native vegetation using heavy machinery and herbicide application. A water catchment and irrigation system was installed, and over 18,000 native plants representing 37 native species were outplanted in the restoration area. The plant species selected are low-in-stature, making burrow excavation easier for seabirds while simultaneously providing forage for Nene (Branta sandvicensis). Habitat restoration was done in phases (10-15% of the project per year) and will be continued until the majority of the area has been restored. In addition to habitat restoration, 50 artificial burrows were installed in the restoration to facilitate translocation activities. From 2012-2017 potential source colonies of NESH and HAPE were located by the Kauai Endangered Seabird Recovery Project (KESRP) with visual, auditory, and ground searching methods at locations around Kauai. The sites that were selected as source colonies for both species were Upper Limahuli Preserve (owned by the National Tropical Botanical Garden; NTBG) and several sites within the Hono o Na Pali Natural Area Reserve system. These sites had high call rates, high burrow densities to provide an adequate source of chicks for the translocation, and had active predator control operations in place to offset any potential impacts of the monitoring. Translocation protocols were developed based on previous methods developed in New Zealand; on the ground training was done by the translocation team by visiting active projects in New Zealand. In year one, 10 HAPE and eight NESH were translocated, and the goal is to translocate up to 20 in subsequent years for a cohort size of 90 birds of each species over a five year period. Post-translocation monitoring has been initiated to gauge the level of success, and social attraction has been implemented in an attempt to attract adults to the area. It is anticipated that the chicks raised during this project will return to breed at Nihoku when they are 65-6 years old; for the first cohort released in 2015 this would be starting in 2020. Once this occurs, Nihoku will be the first predator-free breeding area of both species in Hawaii.This project and manuscript are part of a large collaboration that spans beyond the agencies mentioned. Many individuals were consulted for advice and input along the way. For botanical and invertebrate advice, we thank: David Burney, Lida Burney, Natalia Tangalin, Emory Griffin‐Noyes, Kawika Winter, Kim Starr, Forest Starr, Sheldon Plentovich and Keren Gunderson. For assistance with translocation training and predator exclusion fence technical advice we thank Helen Gummer, John McLennan, Lindsay Wilson, and Darren Peters. For reviewing documents related to this project, and for feedback on techniques we thank the seabird hui, particularly Fern Duvall, Jay Penniman, Megan Laut, Darcy Hu and Cathleen Bailey. For their on the ground assistance at KPNWR, we thank: Shannon Smith, Chadd Smith, Warren Madeira, Rob Petersen, Jennifer Waipa, Padraic Gallagher, Carolyn Rushforth, Kristina Macaulay, Jimmy Macaulay, and Jillian Cosgrove. We would also like to thank Chris Mottley, Kyle Pias and the entire predator control team in Hono o Na Pali NAR and Kawika Winter, Chiemi Nagle, Merlin Edmonds and the entire predator control team in Upper Limahuli Preserve. We would also like to thank the Kaua‘i Island Utility Co‐operative (KIUC) for the funding that they provide – through a Habitat Conservation Plan – to provide predator control and seabird monitoring at several of the sites used for translocation. Lastly, we would like to thank all of the endangered seabird technicians within the Kauaʻi Endangered Seabird Recovery Project for all of their hard work in montane colonies. Mahalo

    Pest categorisation of Pestalotiopsis microspora

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    Following an EFSA commodity risk assessment of bonsai plants (Pinus parviflora grafted on Pinus thunbergii) imported from China, the EFSA Plant Health Panel performed a pest categorisation of Pestalotiopsis microspora, a clearly defined plant pathogenic fungus of the family Pestalotiopsidaceae. The pathogen was reported on a wide range of monocotyledonous, dicotyledonous and gymnosperms, either cultivated or wild plant species, causing various symptoms such as leaf spot, leaf blight, scabby canker, fruit spot, pre- and post-harvest fruit rot and root rot. In addition, the fungus was reported as an endophyte on a wide range of asymptomatic plant species. This pest categorisation focuses on the hosts that are relevant for the EU and for which there is robust evidence that the pathogen was formally identified by a combination of morphology, pathogenicity and multilocus sequencing analyses. Pestalotiopsis microspora was reported in Africa, North, Central and South America, Asia and Oceania. In the EU, it was reported in the Netherlands. There is a key uncertainty on the geographical distribution of P. microspora worldwide and in the EU, because of the endophytic nature of the fungus, the lack of surveys, and because in the past, when molecular tools were not fully developed, the pathogen might have been misidentified as other Pestalotiopsis species or other members of the Pestalodiopsidaceae family based on morphology and pathogenicity tests. Pestalotiopsis microspora is not included in Commission Implementing Regulation (EU) 2019/2072. Plants for planting, fresh fruits, bark and wood of host plants as well as soil and other growing media associated with plant debris are the main pathways for the entry of the pathogen into the EU. Host availability and climate suitability in parts of the EU are favourable for the establishment and spread of the pathogen. The introduction and spread of the pathogen into the EU are expected to have an economic and environmental impact where susceptible hosts are grown. Phytosanitary measures are available to prevent the introduction and spread of the pathogen into the EU. Unless the restricted distribution in the EU is disproven, Pestalotiopsis microspora satisfies all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest

    Pest categorisation of Crisicoccus seruratus

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    Following the commodity risk assessments of Acer palmatum plants grafted on A. davidii from China, in which Crisicoccus matsumotoi (Hemiptera: Pseudococcidae) was identified as a pest of possible concern, the European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of C. matsumotoi for the territory of the European Union. Recent taxonomic revision of the genus Crisisoccus concluded that C. matsumotoi is a synonym of C. seruratus; therefore, the categorisation will use the current valid name C. seruratus. It is an insect pest native to Japan, feeding on species in 13 plant families. There are reports of its presence also in China and the Republic of Korea, but there is great uncertainty about the identity of the species for these records. Therefore, there is uncertainty about the species referred to as C. matsumotoi in the commodity risk assessments of A. palmatum. C. seruratus is a multivoltine species. It has three generations per year and overwinters as a nymph. The most important crops that may be affected by C. seruratus are figs (Ficus carica), grapes (Vitis spp.), nashi pears (Pyrus pyrifolia var. culta), persimmons (Diospyros kaki) and walnuts (Juglans regia). Plants for planting and fruits provide potential pathways for entry into the EU. Host availability and climate suitability suggest that the central, northern and some areas of southern EU countries would be suitable for the establishment of C. seruratus. The introduction of this mealybug would likely have an economic impact in the EU through yield reduction and fruit downgrading because of honeydew deposition and the consequent growth of sooty moulds. This insect is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. Phytosanitary measures are available to reduce the likelihood of entry and spread of this species into the EU. C. seruratus satisfies the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest

    The story of light science: from early theories to today's extraordinary applications

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    This book traces the evolution of our understanding and utilization of light from classical antiquity and the early thoughts of Pythagoras to the present time.   From the earliest recorded theories and experiments to the latest applications in photonic communication and computation, the ways in which light has been put to use are numerous and astounding.  Indeed, some of the latest advances in light science are in fields  that until recently belonged to the realm of science fiction.  The author, writing for an audience of both students and other scientifically interested readers, describes fundamental investigations of the nature of light and ongoing methods to measure its speed as well as the emergence of the wave theory of light and the complementary photon theory.  The importance of light in the theory of relativity is discussed as is the development of electrically-driven light sources and lasers. The information here covers the range of weak single-photon light sources to super-high power lasers and synchrotron light sources.  Many cutting-edge topics are also introduced, including entanglement-based quantum communication through optical fibers and free space, quantum teleportation, and quantum computing. The nature and use of "squeezed light" - e.g. for gravitational wave detection - is another fascinating excursion, as is the topic of fabricated metamaterials, as used to create invisibility cloaks. Here the reader also learns about the realization of extremely slow speed and time-reversed light. The theories, experiments, and applications described in this book are, whenever possible, derived from original references.  The many annotated drawings and level of detail make clear the goals, procedures, and conclusions of the original investigators. Where they are required, all specialist terms and mathematical symbols are defined and explained. The final part of the book covers light experi ments in the free space of the cosmos, and also speculates about scenarios for the cosmological origins of light and the expected fate of the photon in a dying universe. The final part of the book covers light experiments in the free space of the cosmos, and also speculates about scenarios for the cosmological origins of light and the expected fate of the photon in a dying universe

    THE TEMPERATURE DEPENDENCE OF THE TOTAL ABSORPTANCE OF SOME MINOR ATMOSPHERIC GASES∗GASES^{\ast}

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    ∗^{\ast} This work has been supported in part by the Air Force Cambridge Research Laboratories, Office of Aerospace Research, under a contract with the Ohio State University Research Foundation.Author Institution: Laboratory of Molecular Spectroscopy and Infrared Studies, Department of Physics, The Ohio State UniversityThe dependence of the total absorptance of the bands of carbon monoxide near 4.7ÎŒ4.7 \mu and 2.3ÎŒ2.3 \mu, and of methane near 3.3ÎŒ3.3 \mu, on absorber concentration, pressure, and temperature was measured. Data were taken for absorber pressures between 100 and 1000 mm Hg, and at temperatures up to 400∘C400^{\circ}C, for a fixed absorber path length of 30.6 cm. The nature and possible reasons for the observed temperature dependence of the total absorptance are discussed
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