4,746 research outputs found

    Constant gardeners: Endozoochory promotes repeated seedling recruitment in clonal plants

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    [EN] Paradoxically, seedlings of clonal plants are rarely observed in nature, despite many of these species producing large amounts of seeds every fruiting season. Studies about clonal plants’ recruitment strategies are usually based on experiments carried out under controlled conditions (e.g., laboratory) and rarely consider frugivores’ effects. We tested the role of endozoochory in the seedling recruitment in natural conditions of the bilberry Vaccinium myrtillus, a widely distributed clonal species and a key resource in temperate and boreal regions of Eurasia, which has been suggested to recruit at occasional windows of opportunity (unpredictable conditions in which seedling recruitment may occur within conspecific adult stands). We marked brown bear Ursus arctos, mesocarnivore (red foxes Vulpes vulpes and martens Martes spp.) and passerine feces containing bilberry seeds in the Tatra Mountains (Carpathian Mountains, Southern Poland) and followed the fate of the embedded seeds during two years. We detected bilberry germination associated with 100%, 87.5%, and 50% of brown bear, mesocarnivore, and passerine feces, and also in 43.6%, 41.2%, and 23.1% of the control plots located 5, 10, and 30 m away from the bear scats, respectively. In bear scats, investigated in more detail, 15.7% of the seedlings survived at least one year. The largest numbers of seedlings were associated with bear scats (154.4 ± 237.3 seedlings/m2), especially to those defecated upon the soil disturbances these animals create next to their resting sites. Our results demonstrate that endozoochory facilitates repeated bilberry seedling recruitment in nature, suggesting that studies on the reproductive strategies of clonal plants must consider the role of frugivores. Some frugivores’ behaviors, such as the defecation by bears in the vicinity of their resting sites, may in fact be crucial for the reproduction of clonal plants and for the adaptation of these species to the current changing climatic conditionsSIThis study was supported by the BearConnect project funded by the National Science Centre in Poland (2016/22/Z/NZ8/00121) through the 2015–2016 BiodivERsA COFUND call for research proposals, with the national funders ANR/DLR-PT/UEFISCDI/NCN/ RCN. We thank Aida Parres, Danuta Frydryszak, Carlos Bautista, Katarzyna Chrzaz scik, and Max Murgio for their help during the fieldwork and Tomasz Zwijacz-Kozica for providing the GPS locations of brown bear clusters. Tatra National Park provided the necessary permits to conduct the field work. A stimulating discussion with Sam Steyaert and comments made by two anonymous reviewers improved the overall quality of this manuscript. AGR and NS conceived the study, designed the methodology, and conducted the fieldwork. AGR performed all statistical analyses and wrote a first draft of the manuscript with significant contributions of NS. The authors declare no conflict of interes

    Chaos controller for switching regulators aiming enhanced design-space towards miniaturization

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    This paper tackles the control of fast-scale instabilities in a buck switching power converter aiming to expand its design-space towards miniaturization. After briefly revisiting the working principle of existing chaos controllers, the paper explores an alternative approach based on amplifying the harmonic at the switching frequency. Numerical simulations show that the proposed controller can concurrently improve both fast-scale and slow-scale stability margins. Finally, the paper proposes a chaos controller combined with an output ripple reduction network and studies their interaction with the aim of achieving both low-ripple and improved stability.Preprin

    Contribuciones a la flora de Palencia (España)

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    Se comentan una serie de citas de plantas vasculares encontradas en la provincia de Palencia (Castilla y León, España) que resultan raras en estos territorios.SUMMARY: Several new or rare taxa of vascular plants found in the region of Palencia (Castilla y León, Spain) are here commented

    Effect of Degradation on Wood Hygroscopicity: The Case of a 400-Year-Old Coffin

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    The hygroscopicity and thermodynamic properties of Pinus sylvestris L. wood from a coffin allegedly holding the remains of famous Spanish author Miguel de Cervantes Saavedra (1547–1616) were studied using the 15 ◦C and 35 ◦C isotherms fitted to the Guggenheim–Anderson–de Boer model and comparing them with the isotherms of recently felled wood of the same species. In addition, using infrared spectroscopy (FTIR-ATR) and X-ray diffractograms, the functional groups were determined and the crystallinity and organization of the cell wall components were analyzed. The absence of the 1740 cm−1 group indicates hemicellulose degradation in the archaeological wood, and the X-ray diffractograms show a considerable decrease in cellulose crystallinity and disorganization of the cellulose crystallites. The greater availability of active –OH groups means that the archaeological wood isotherms are above the juvenile and mature wood isotherms, and therefore the thermodynamic balance in the sorption of the archaeological wood is greater

    Multi-homing tunnel broker

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    A proper support for communications has to provide fault tolerance capabilities such as the preservation of established connections in case of failures. Multihoming addresses this issue, but the currently available solution based in massive BGP route injection presents serious scalability limitations, since it contributes to the exponential growth of the BGP table size. An alternative solution based on the configuration of tunnels between the multihomed site exit routers and the ISP border routers has been proposed for IPv6 in RFC 3178. However, the amount of manual configuration imposed by this solution on the ISP side prevents its wide adoption. In particular, this solution requires at the ISP the manual configuration of a tunnel endpoint per each multihomed client that it serves. We present a multihoming tunnel broker (MHTB) that provides automatic creation of the tunnel endpoint at the ISP side.This work was supported by the SAM (Advanced Servers with Mobility)project, funded by the Spanish National research and Development Programme as TIC2002-04531-C04-03.Publicad

    Creative and collective writing in the context of the new cultural practices

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    Se plantea en este artículo el cambio profundo que, en la nueva cultura del siglo XXI, ha sufrido el concepto de creación colectiva, por influencia de Internet. Las redes sociales, la cultura participativa, la convergencia de los medios y otros factores han favorecido nuevos modos de expresión, al margen de la escritura académica o profesional, como ha sido el caso de la ficción-manía. Sobre el concepto de creación colectiva se está escribiendo mucho, a propósito de la épica y de otros temas literarios y debe ser “iluminado” a la luz de lo que Internet o los nuevos fenómenos, como el auge de las sagas fantásticas o la ficción-manía, están suponiendo. Así, lo que actualmente se denomina escritura colaborativa es en realidad un concepto que ha ido evolucionando de forma acompasada con las poéticas y las prácticas sociales de la lectura en los últimos tiempos. Revisamos los rasgos de estas nuevas prácticas y se analizan las implicaciones para la educación del siglo XXI.The deep change that, in the new culture of the 21st century, has suffered the concept of collective creation, under the influence of the Internet is proposed in this article. Social networking, participatory culture, the convergence of media and other factors have favored new ways of expression, apart from academic or professional writing, as it has been the case of the fan fiction. There is a lot of studies nowadays on the concept of collective creation, with regard to epic and other literary topics and should be “enlightened” in the light of what Internet or new phenomena, such as the rise of fantasy sagas or the fan fiction, are involving. So, what is currently referred to as collaborative writing is actually a concept that has evolved in a measured way with the poetic and social practices of reading in last times. We review the features of these new practices and examine the implications for the education of the 21st century.peerReviewe

    Tests Management in CALIPSOneo: A MDE Solution

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    Testing in Software Engineering is one of the most important phases although, unfortunately, it cannot be always successfully fulfilled due to time constraints. In most cases, the development phase takes more time than it was estimated, entailing negative effects on the testing phase. The delay increases even more in Research and Development (R + D) projects, where the real time to execute tasks is more difficult to control. Model Driven Engineering (MDE) offers a solution to avoid testing costs without affecting the execution quality of the applied test. This paper presents a practical overview of a Model Driven Testing (MDT)-based methodology and its impact on CA LIPSOneo project, which was carried out in liaison with Airbus Defense and Space and, particularly, with the Product Lifecycle Management (PLM) departmentMinisterio de Ciencia e Innovación TIN2013-46928-C3-3-RJunta de Andalucía TIC-578
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