392 research outputs found

    Experimental tests of a seasonally changing visual preference for habitat in a long-distance migratory shorebird

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    Migratory shorebirds show highly organized seasonal cycles in physiological and morphological traits (body mass and composition, plumage, hormone levels, etc.), which in captivity is accompanied by restless behaviour at times when free-living birds would start migration. We introduce the idea that seasonally changing preference for habitat could motivate migrants to embark on migration and that this cognitive process could also guide them to seasonally appropriate places. We explored this by testing whether red knots (Calidris canutus), which also in captivity maintain marked circannual phenotypic rhythms, show evidence of seasonal change in preference for pictures of seasonally appropriate habitats. We first developed a method to verify whether red knots are able to memorize and discriminate contrasting pictures projected by LCD projectors. This was followed by two different experiments in which we tested for a seasonally changing preference for breeding or non-breeding habitat. When carried out during the pre-breeding season, the red knots are expected to prefer pictures of mudflats, their non-breeding habitat. At the start of the breeding season, they should prefer pictures of the tundra breeding habitat. We established that knots are able to distinguish and memorize projected images. We failed to demonstrate the predicted change in vision-based habitat preference, but for reasons of test design we do not interpret this as a strong rejection of the hypothesis. Instead, we suggest that experiments with greater numbers of individuals tested once, perhaps in combination with the provision of additional cues such as smells and sounds, will help the development of these ideas further

    Long-term Outcome Following Thrombembolectomy in the Upper Extremity

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    AbstractObjectivesTo evaluate short- and long-term mortality and morbidity in patients that were treated for acute upper extremity ischemia.DesignSingle center retrospective study.PatientsA consecutive series of 148 patients who were admitted with a diagnosis of acute ischemia of the upper extremity during an 11-year period.MethodsAll charts were reviewed retrospectively and 96% of all survivors participated in clinical follow-up.ResultsThe median age was 78 years and 64% of patients were females. The 30-day mortality was 8% and the overall 5-year survival 37%. The observed mortality during the follow-up period was significantly higher than expected. Survival was not significantly different in patients who received anticoagulant drugs following discharge from the hospital. The duration of ischemia did not significantly influence long-term arm-function.ConclusionsAcute embolic episodes in the upper extremity primarily occur in elderly and the peri-operative mortality is high. Mortality following discharge from the hospital remains significantly higher than that of the background population

    New generation hole transporting materials for perovskite solar cells: amide-based small-molecules with nonconjugated backbones

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    State‐of‐the‐art perovskite‐based solar cells employ expensive, organic hole transporting materials (HTMs) such as Spiro‐OMeTAD that, in turn, limits the commercialization of this promising technology. Herein an HTM (EDOT‐Amide‐TPA) is reported in which a functional amide‐based backbone is introduced, which allows this material to be synthesized in a simple condensation reaction with an estimated cost of <$5 g−1. When employed in perovskite solar cells, EDOT‐Amide‐TPA demonstrates stabilized power conversion efficiencies up to 20.0% and reproducibly outperforms Spiro‐OMeTAD in direct comparisons. Time resolved microwave conductivity measurements indicate that the observed improvement originates from a faster hole injection rate from the perovskite to EDOT‐Amide‐TPA. Additionally, the devices exhibit an improved lifetime, which is assigned to the coordination of the amide bond to the Li‐additive, offering a novel strategy to hamper the migration of additives. It is shown that, despite the lack of a conjugated backbone, the amide‐based HTM can outperform state‐of‐the‐art HTMs at a fraction of the cost, thereby providing a novel set of design strategies to develop new, low‐cost HTMs

    New generation hole transporting materials for perovskite solar cells: amide-based small-molecules with nonconjugated backbones

    Get PDF
    State‐of‐the‐art perovskite‐based solar cells employ expensive, organic hole transporting materials (HTMs) such as Spiro‐OMeTAD that, in turn, limits the commercialization of this promising technology. Herein an HTM (EDOT‐Amide‐TPA) is reported in which a functional amide‐based backbone is introduced, which allows this material to be synthesized in a simple condensation reaction with an estimated cost of <$5 g−1. When employed in perovskite solar cells, EDOT‐Amide‐TPA demonstrates stabilized power conversion efficiencies up to 20.0% and reproducibly outperforms Spiro‐OMeTAD in direct comparisons. Time resolved microwave conductivity measurements indicate that the observed improvement originates from a faster hole injection rate from the perovskite to EDOT‐Amide‐TPA. Additionally, the devices exhibit an improved lifetime, which is assigned to the coordination of the amide bond to the Li‐additive, offering a novel strategy to hamper the migration of additives. It is shown that, despite the lack of a conjugated backbone, the amide‐based HTM can outperform state‐of‐the‐art HTMs at a fraction of the cost, thereby providing a novel set of design strategies to develop new, low‐cost HTMs

    Cholestase bij pasgeborenen als gevolg van parenterale voeding

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    Toediening van totale parenterale voeding (TPN) aan pasgeborenen is geassocieerd met het ontstaan van cholestase. Ondanks intensief onderzoek zijn de pathofysiologische mechanismen slechts gedeeltelijk opgehelderd. In dit artikel wordt ingegaan op de huidige inzichten in de risicofactoren die geassocieerd zijn met TPN-cholestase bij pasgeborenen, de specifieke bestanddelen en deficiënties van TPN die cholestase kunnen veroorzaken, de mogelijke relatie met de ‘fysiologische cholestase van de pasgeborene’, die de pasgeborene kwetsbaarder maakt voor potentieel hepatotoxische stoffen, en de transportsystemen in de levercelmembraan die betrokken zijn bij galvorming. De hypothese dat ‘cholestatische galzuren’ een rol spelen in de etiologie van TPN-cholestase en de therapeutische mogelijkheden worden besproken.Administration of total parenteral nutrition (TPN) to neonates is associated with the occurrence of cholestasis. Despite intensive research, the pathophysiological mechanisms have not been elucidated. In this review we describe the present insights into the risk factors for the development of TPN-associated cholestasis, the specific components or lack of components (deficiencies) in TPN that can cause cholestasis, the possible correlation with 'physiologic cholestasis of the neonate', which makes the infant more susceptible for potentially hepatotoxic compounds, and the transport systems in the liver cell membrane which are involved in bile formation. The hypothesis that 'cholestatic bile salts' play a role in the etiology of TPN-related cholestasis and the therapeutic options will be discussed.</p

    Intelligent Monitoring System for Bird Behavior Study

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    Until now, the best way to obtain relevant information about the behaviour of animals is capturing them. However, the procedure to capture individuals cause them stress and introduces an effect on the measurement that can affect the behaviour of the animals. To solve this problems this paper describes a novel intelligent motoring system for birds breeding in nest boxes. This system is based in a network of smart-nest boxes that allows access to the acquired data all over the world through internet. A prototype of the proposed system has been implemented for the evaluation of a lesser kestrel breeding colony in Southern Spain. This prototype has offered in a short time more valuable information that several years of manual captures. This prototype has demonstrated that the proposed system allows short and log time animal behaviour evaluation without interferences or causing stress.Junta de Andalucía P06-RNM-01712Junta de Andalucía P06-RNM-04588Junta de Andalucía P07-TIC-02476Junta de Andalucía TIC-570

    Mutual facilitation between foundation species Mytilus edulis and Lanice conchilega promotes habitat heterogeneity on tidal flats

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    Foundation species that modify their habitat can facilitate other species, including other foundation species. Most studies focus solely on a single foundation species, overlooking such facilitation cascades. In this study, we investigated the interactions between the two coastal foundation species Mytilus edulis (blue mussel) and Lanice conchilega (sand mason worm). We investigated whether these species engage in facilitative interactions or if their association simply reflects a shared ecological niche on the soft-sediment intertidal flats of the Dutch Wadden Sea. To do so, we performed species distribution modeling, manipulative field experiments, and field surveys. We found a positive association between both foundation species, with a 2.45 times higher occurrence of both species compared to a random distribution. In addition, these species partially occupied the same ecological niche. We demonstrated that L. conchilega provided settlement substrate for M. edulis spat, increasing densities by 400 times compared to bare plots. Furthermore, M. edulis reefs facilitated L. conchilega occurrence in the wake of the reef. Biogenic reef development revealed that this interspecific facilitation resulted in spatial habitat heterogeneity. Therefore, we conclude that interspecific facilitation can significantly enhance the occurrence of these two important intertidal foundation species. Acknowledgment of such complex facilitation interactions has an untapped potential for improving the success of restoration and conservation programs.</p
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