2,248 research outputs found

    A Study of the Dynamics of Dust from the Kuiper Belt: Spatial Distribution and Spectral Energy Distribution

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    The dust produced in the Kuiper Belt (KB) spreads throughout the Solar System forming a dust disk. We numerically model the orbital evolution of KB dust and estimate its equilibrium spatial distribution and its brightness and spectral energy distributions (SED), assuming greybody absorption and emission by the dust grains. We show that the planets modify the KB disk SED, so potentially we can infer the presence of planets in spatially unresolved debris disks by studying the shape of their SEDs. We point out that there are inherent uncertainties in the prediction of structure in the dust disk, owing to the chaotic dynamics of dust orbital evolution imposed by resonant gravitational perturbations of the planets.Comment: 19 pages, 14 figures in jpg, accepted to A

    A holistic approach to enhance the use of neglected and underutilized species: the case of Andean grains in Bolivia and Peru

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    The IFAD-NUS project, implemented over the course of a decade in two phases, represents the first UN-supported global effort on neglected and underutilized species (NUS). This initiative, deployed and tested a holistic and innovative value chain framework using multi-stakeholder, participatory, inter-disciplinary, pro-poor gender- and nutrition-sensitive approaches. The project has been linking aspects often dealt with separately by R&D, such as genetic diversity, selection, cultivation, harvest, value addition, marketing, and final use, with the goal to contribute to conservation, better incomes, and improved nutrition and strengthened livelihood resilience. The project contributed to the greater conservation of Andean grains and their associated indigenous knowledge, through promoting wider use of their diversity by value chain actors, adoption of best cultivation practices, development of improved varieties, dissemination of high quality seed, and capacity development. Reduced drudgery in harvest and postharvest operations, and increased food safety were achieved through technological innovations. Development of innovative food products and inclusion of Andean grains in school meal programs is projected to have had a positive nutrition outcome for targeted communities. Increased income was recorded for all value chain actors, along with strengthened networking skills and self-reliance in marketing. The holistic approach taken in this study is advocated as an effective strategy to enhance the use of other neglected and underutilized species for conservation and livelihood benefits

    Time Shared Optical Network (TSON): a novel metro architecture for flexible multi-granular services

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    This paper presents the Time Shared Optical Network (TSON) as metro mesh network architecture for guaranteed, statistically-multiplexed services. TSON proposes a flexible and tunable time-wavelength assignment along with one-way tree-based reservation and node architecture. It delivers guaranteed sub-wavelength and multi-granular network services without wavelength conversion, time-slice interchange and optical buffering. Simulation results demonstrate high network utilization, fast service delivery, and low end-to-end delay on a contention-free sub-wavelength optical transport network. In addition, implementation complexity in terms of Layer 2 aggregation, grooming and optical switching has been evaluated

    Evaluating White Clover for Resistance to Cylindrocladium Root Rot

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    A rapid screening technique was developed for use in evaluating white clover (Trifolium repens L.) for resistance to Cylindrocladium root rot incited by Cylindrocladium crotalariae. Culture plates of the fungus were evaluated for number of infective propagules after four weeks of growth on potato dextrose agar, and no differences were detected among plates. Seedlings of ‘Osceola’ white clover were exposed in the greenhouse to four levels of inoculum over a six-week period, with resistance based on percent survival of uninoculated controls. It was shown that suspending 1 culture plate in 100ml of water and rating plants four weeks after inoculation was suitable for screening seedlings. A field test was conducted to verify greenhouse results. Results indicated that the greenhouse technique gave similar results, and would be sufficient to use in a breeding program to develop resistance to this disease

    Field trial of a 15 Tb/s adaptive and gridless OXC supporting elastic 1000-fold all-optical bandwidth granularity

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    An adaptive gridless OXC is implemented using a 3D-MEMS optical backplane plus optical modules (sub-systems) that provide elastic spectrum and time switching functionality. The OXC adapts its architecture on demand to fulfill the switching requirements of incoming traffic. The system is implemented in a seven-node network linked by installed fiber and is shown to provide suitable architectures on demand for three scenarios with increasing traffic and switching complexity. In the most complex scenario, signals of mixed bit-rates and modulation formats are successfully switched with flexible per-channel allocation of spectrum, time and space, achieving over 1000-fold bandwidth granularity and 1.5 Tb/s throughput with good end-to-end performance

    Highly efficient bi-allelic mutation rates using TALENs in Xenopus tropicalis

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    In the past decade, Xenopus tropicalis has emerged as a powerful new amphibian genetic model system, which offers all of the experimental advantages of its larger cousin, Xenopus laevis. Here we investigated the efficiency of transcription activator-like effector nucleases (TALENs) for generating targeted mutations in endogenous genes in X. tropicalis. For our analysis we targeted the tyrosinase (oculocutaneous albinism IA) (tyr) gene, which is required for the production of skin pigments, such as melanin. We injected mRNA encoding TALENs targeting the first exon of the tyr gene into two-cell-stage embryos. Surprisingly, we found that over 90% of the founder animals developed either partial or full albinism, suggesting that the TALENs induced bi-allelic mutations in the tyr gene at very high frequency in the F0 animals. Furthermore, mutations tyr gene were efficiently transmitted into the F1 progeny, as evidenced by the generation of albino offspring. These findings have far reaching implications in our quest to develop efficient reverse genetic approaches in this emerging amphibian model

    Experimental demonstration of gridless spectrum and time optical switching

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    An experimental demonstration of gridless spectrum and time switching is presented. We propose and demonstrate a bit-rate and modulation-format independent optical cross-connect architecture, based on gridless spectrum selective switch, 20-ms 3D-MEMS and 10-ns PLZT optical switches, that supports arbitrary spectrum allocation and transparent time multiplexing. The architecture is implemented in a four-node field-fiber-linked testbed to transport continuous RZ and NRZ data channels at 12.5, 42.7 and 170.8 Gb/s, and selectively groom sub-wavelength RZ channels at 42.7 Gb/s. We also showed that the architecture is dynamic and can be reconfigured to meet the routing requirements of the network traffic. Results show error-free operation with an end-to-end power penalty between 0.8 dB and 5 dB for all continuous and sub-wavelength channels

    Reacción seudoséptica tras la infiltración de ácido hialurónico en el tratamiento de la artrosis de tobillo: a propósito de un caso

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    Muchos cirujanos ortopédicos utilizan las infiltraciones de ácido hialurónico como tratamiento sintomático de la artrosis. Generalmente su uso es seguro, pero en ocasiones puede presentar alguna reacción adversa que se debe conocer, como la reacción pseudoséptica. Presentamos un caso de un varón de 48 años que acude a urgencias con fiebre y signos inflamatorios en tobillo tras la segunda infiltración de ácido hialurónico. Se realizó un artrotomía de limpieza y el cultivo de la muestra resultó negativo. Discusión: La importancia de la reacción seudoséptica radica en que es una entidad clínica superponible a una verdadera artritis séptica pero que, a diferencia de la anterior, se resuelve con reposo y antiinflamatorios, y no produce alteraciones en el cartílago.Most of the orthopedists use intraarticular supplementation of hyaluronic acid to relieve osteoarthritis ´pain. Usually this treatment is safe but, sometimes it has some adverse events that should be known, as the pseudoseptic reaction or severe acute inflammatory reaction. We present a 48 years old man that presented fever and inflammatory reaction in his ankle after the second intraarticular injection of hyaluronate. An ankle arthrotomy was performed, but the culture results were negative. Discusion: We may consider the difference between this reaction and a real septic disease, that requires antibioterapy and, in most cases, surgery. Otherwise, the pseudoseptic reaction improves with rest and anti-inflammatory drugs, and does not suppose a damage to the cartilage

    S-matrix poles and the second virial coefficient

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    For cutoff potentials, a condition which is not a limitation for the calculation of physical systems, the S-matrix is meromorphic. We can express it in terms of its poles, and then calculate the quantum mechanical second virial coefficient of a neutral gas. Here, we take another look at this approach, and discuss the feasibility, attraction and problems of the method. Among concerns are the rate of convergence of the 'pole' expansion and the physical significance of the 'higher' poles.Comment: 20 pages, 8 tables, submitted to J. Mol. Phy
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