5,663 research outputs found

    Geometry of Empty Space is the Key to Near-Arrest Dynamics

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    We study several examples of kinetically constrained lattice models using dynamically accessible volume as an order parameter. Thereby we identify two distinct regimes exhibiting dynamical slowing, with a sharp threshold between them. These regimes are identified both by a new response function in dynamically available volume, as well as directly in the dynamics. Results for the selfdiffusion constant in terms of the connected hole density are presented, and some evidence is given for scaling in the limit of dynamical arrest.Comment: 11 page

    A new analysis of the WASP-3 system: no evidence for an additional companion

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    In this work we investigate the problem concerning the presence of additional bodies gravitationally bounded with the WASP-3 system. We present eight new transits of this planet and analyse all the photometric and radial velocity data published so far. We did not observe significant periodicities in the Fourier spectrum of the observed minus calculated (O-C) transit timing and radial velocity diagrams (the highest peak having false-alarm probabilities of 56 per cent and 31 per cent, respectively) or long-term trends. Combining all the available information, we conclude that the radial velocity and transit timing techniques exclude, at 99 per cent confidence limit, any perturber more massive than M \gtrsim 100 M_Earth with periods up to 10 times the period of the inner planet. We also investigate the possible presence of an exomoon on this system and determined that considering the scatter of the O-C transit timing residuals a coplanar exomoon would likely produce detectable transits. This hypothesis is however apparently ruled out by observations conducted by other researchers. In case the orbit of the moon is not coplanar the accuracy of our transit timing and transit duration measurements prevents any significant statement. Interestingly, on the basis of our reanalysis of SOPHIE data we noted that WASP-3 passed from a less active (log R'_hk=-4.95) to a more active (log R'_hk=-4.8) state during the 3 yr monitoring period spanned by the observations. Despite no clear spot crossing has been reported for this system, this analysis claims for a more intensive monitoring of the activity level of this star in order to understand its impact on photometric and radial velocity measurements.Comment: MNRAS accepted (14/08/2012

    Seedling Production Systems for Smallholder Forestry Development: Local Practices versus National Policies in the Philippines

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    The tree seedling nursery sector in the Philippines is influenced by a number of national level policies affecting the number and type of species produced. Policies favour high-volume production of a limited range of mostly exotic species, and research indicates that seedlings are often of low physical and genetic quality. Local knowledge on best species for sites is not being communicated to people planting. A project funded by the Australian Centre for International Agricultural Research is investigating measures to improve the performance and effectiveness of the forestry seedling production system in Leyte and Mindanao in the Philippines. Seedlings are produced by government agencies, in community forestry projects and by individual private operators; the main customers are smallholder tree farmers. Communities and private individuals quickly set up nurseries when there is a demand for seedlings, but these nurseries tend to be ephemeral and lack financial sustainability. While large nurseries offer opportunities for economies of scale, small nurseries operate on a low cost basis, and are more widely distributed, and their seedlings are more accessible to smallholders, who lack transport facilities. Small private nurseries, while having limited access to new technology, often produce seedlings of quality similar to government and community nurseries. However, they require assistance in access to high-quality germplasm and training in improved seed production technology, to play a greater role in expansion of plantation forestry. This paper reports survey findings on seedling production systems, and examines the link between national level policies and local level practices

    Finite-size effects for anisotropic bootstrap percolation: logarithmic corrections

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    In this note we analyze an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.Comment: Key words: Bootstrap percolation, anisotropy, finite-size effect

    Safety and effectiveness of a new electrical detachable microcoil for embolization of hemorrhoidal disease, November 2020–December 2021: results of a prospective study

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    Purpose: The purpose of this study was to prospectively evaluate the efficacy and safety of a new, bare platinum, detachable microcoil as a metallic embolization agent in the treatment of hemorrhoidal disease. Material and Methods: This prospective single-center study evaluated a new, bare platinum, electrical, detachable microcoil (Prestige plus coil (Balt Montmorency France)) for use in vascular embolization in patients with hemorrhoidal disease. Between January 2020 and January 2021, 24 embolization procedures were performed in 21 patients (12 males, 9 females; mean age 44.3 ± 7.3). The inclusion criteria were: (a) participants with grade I, II and III hemorrhoidal disease on the Goligher classification; (b) patients older than 18 years of age with a score of greater than 4 on the French bleeding score (FBS) scale; (c) patients with scores greater than 2 on the scale of discomfort proposed by Tradi and Farfallah. (d) patients who underwent treatment that included the use of the new novel coil (Prestige plus coil (Balt)) as an embolic material. The exclusion criteria were participants who failed to provide informed consent and participants diagnosed with rectal bleeding due to other causes (cancer, fissures or others). Participants with severe renal insufficiency, non-correctable coagulation abnormalities and adverse reactions to the contrast medium not correctable with medication were also excluded. The symptoms, technical aspects, the transarterial approach, clinical and technical success complications and short-term outcomes were assessed. Results: Technical success was obtained in 100% of the cases. Seventeen (80.9%) patients experienced improvements in their hemorrhoidal disease. The VAS and QL scores improved by 4 and 1.5 points (81.2% and 87.5%), respectively, after embolization (pV: 0001). Three (14.2%) patients underwent a second embolization due to rebleeding. One patient (4.7%) underwent surgery. No major complications were observed. Three patients had minor complications. The assessment of subjective post-treatment symptoms and QL surveys showed significant differences from the baseline survey. Likewise, the measurement of the degree of satisfaction using a telephone survey at 12 months revealed a high degree of patient satisfaction over 10 points (mean 8.3 ± 1.1). Conclusions: The present study demonstrates that the use of the new, platinum, detachable, electrical microcoil is safe and well-tolerated in the treatment of hemorrhoidal disease. Key points: Catheter-directed hemorrhoidal dearterialization (CDHD) is the procedure of embolization with embolic agents for the treatment of internal hemorrhoids. CDHD is a simple and safe procedure that is accepted by patients and preserves the anal sphincter; it presents few complications when metal devices or microspheres are used as embolic agents. As the recommended embolization agent in treatments, the Prestige electrical, detachable coil is a safe, easy-to-use and effective arterial embolic device
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