440 research outputs found

    Olfaction Contributes to Pelagic Navigation in a Coastal Shark.

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    How animals navigate the constantly moving and visually uniform pelagic realm, often along straight paths between distant sites, is an enduring mystery. The mechanisms enabling pelagic navigation in cartilaginous fishes are particularly understudied. We used shoreward navigation by leopard sharks (Triakis semifasciata) as a model system to test whether olfaction contributes to pelagic navigation. Leopard sharks were captured alongshore, transported 9 km offshore, released, and acoustically tracked for approximately 4 h each until the transmitter released. Eleven sharks were rendered anosmic (nares occluded with cotton wool soaked in petroleum jelly); fifteen were sham controls. Mean swimming depth was 28.7 m. On average, tracks of control sharks ended 62.6% closer to shore, following relatively straight paths that were significantly directed over spatial scales exceeding 1600 m. In contrast, tracks of anosmic sharks ended 37.2% closer to shore, following significantly more tortuous paths that approximated correlated random walks. These results held after swimming paths were adjusted for current drift. This is the first study to demonstrate experimentally that olfaction contributes to pelagic navigation in sharks, likely mediated by chemical gradients as has been hypothesized for birds. Given the similarities between the fluid three-dimensional chemical atmosphere and ocean, further research comparing swimming and flying animals may lead to a unifying paradigm explaining their extraordinary navigational abilities

    Electric and hydrogen buses : Shifting from conventionally fuelled cars in the UK

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    This research was carried out under the UK Energy Research Centre (UKERC) as part of the ADdressing Valuation of Energy and Nature Together (ADVENT) funded project. Funding was received from the Natural Environment Research Council (NE/M019691/1), United Kingdom and the School of Biological Sciences, University of Aberdeen, United Kingdom. The authors would also like to thank Dr Christian Brand, University of Oxford, for giving them access to the Transport Energy and Air Pollution Model UK (TEAM - UK).Peer reviewedPublisher PD

    The application of travel demand management initiatives within a university setting

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    This research was undertaken as part of the UK Energy Research Centre (UKERC) research programme under the ADdressing Valuation of Energy and Nature Together (ADVENT) project, funded by the Natural Environment Research Council (NE/M019691/1) United Kingdom. Funding was also received from the School of Biological Sciences at the University of Aberdeen, United Kingdom. The authors would like to thank Dr Kate Pangbourne, The University of Leeds, for their detailed and constructive feedback on this paper. The authors would also like to acknowledge Dr Alex Douglas for their input in the methodology.Peer reviewedPostprin

    Electric and hydrogen rail : Potential contribution to net zero in the UK

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    Acknowledgements  This research was carried out under the UK Energy Research Centre (UKERC) as part of the ADdressing Valuation of Energy and Nature Together (ADVENT) funded project. Funding was received from the Natural Environment Research Council (NE/M019691/1), United Kingdom and the School of Biological Sciences, University of Aberdeen, United Kingdom. The authors would also like to thank Dr Christian Brand, University of Oxford, for giving them access to the Transport Energy and Air Pollution Model (TEAM-UK).Peer reviewedPublisher PD

    Japan and the UK : Emission predictions of electric and hydrogen rail to 2050

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    Acknowledgements This research was carried out under the UK Energy Research Centre (UKERC) as part of the ADdressing Valuation of Energy and Nature Together (ADVENT) funded project. Funding was received from the Natural Environment Research Council (NE/M019691/1), United Kingdom and the School of Biological Sciences, University of Aberdeen, United Kingdom. Funding was also received from the Postgraduate Research Grant from University of Aberdeen, United Kingdom. This work has also emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) under the SFI Strategic Partnership Programme Grant number SFI/15/SPP/E3125. The authors would also like to thank Dr Christian Brand, University of Oxford, for giving them access and guidance regarding the Trans- port Energy and Air Pollution Model (TEAM‐UK).Peer reviewedPublisher PD

    Inhibition of delta-like ligand 4 induces luteal hypervascularization followed by functional and structural luteolysis in the primate ovary

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    Using specific inhibitors established that angiogenesis in the ovarian follicle and corpus luteum is driven by vascular endothelial growth factor. Recently, it has been demonstrated that the Notch ligand, delta-like ligand 4 (Dll4) negatively regulates vascular endothelial growth factor-mediated vessel sprouting and branching. To investigate the role of Dll4 in regulation of the ovarian vasculature, we administered a neutralizing antibody to Dll4 to marmosets at the periovulatory period. The vasculature was examined on luteal d 3 or d 10: angiogenesis was determined by incorporation of bromodeoxyuridine, staining for CD31 and cell death by staining for activated caspase-3. Ovulatory progesterone rises were monitored to determine effects of treatment on luteal function and time to recover normal cycles in a separate group of animals. Additionally, animals were treated in the follicular or midluteal phase to determine effects of Dll4 inhibition on follicular development and luteal function. Controls were treated with human IgG (Fc). Corpora lutea from marmosets treated during the periovulatory period exhibited increased angiogenesis and increased vascular density on luteal d 3, but plasma progesterone was significantly suppressed. By luteal d 10, corpora lutea in treated ovaries were significantly reduced in size, with involution of luteal cells, increased cell death, and suppressed plasma progesterone concentrations. In contrast, initiation of anti-Dll4 treatment during the midluteal phase produced only a slight suppression of progesterone for the remainder of the cycle. Moreover, Dll4 inhibition had no appreciable effect on follicular development. These results show that Dll4 has a specific and critical role in the development of the normal luteal vasculature

    Metabolic molecular markers of the tidal clock in the marine crustacean Eurydice pulchra

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    SummaryIn contrast to the well mapped molecular orchestration of circadian timekeeping in terrestrial organisms, the mechanisms that direct tidal and lunar rhythms in marine species are entirely unknown. Using a combination of biochemical and molecular approaches we have identified a series of metabolic markers of the tidal clock of the intertidal isopod Eurydice pulchra. Specifically, we show that the overoxidation of peroxiredoxin (PRX), a conserved marker of circadian timekeeping in terrestrial eukaryotes [1], follows a circatidal (approximately 12.4 hours) pattern in E. pulchra, in register with the tidal pattern of swimming. In parallel, we show that mitochondrially encoded genes are expressed with a circatidal rhythm. Together, these findings demonstrate that PRX overoxidation rhythms are not intrinsically circadian; rather they appear to resonate with the dominant metabolic cycle of an organism, regardless of its frequency. Moreover, they provide the first molecular leads for dissecting the tidal clockwork

    ESD Terms and Definitions (Version 12)

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    Basic terms related to engineering system

    Reassessing the Fighting Performance of Conscript Soldiers During the Malvinas/Falklands War (1982)

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    While the idea is controversial, it is quite possible that, at least under certain circumstances, the fighting effectiveness of a conscript army can equal that of a professional army. For any army, fighting effectiveness is not only influenced by the degree of psychological cohesion among soldiers and officers, but also by the organizational culture of each particular service unit towards the preparation for war and the waging of the conflict itself. The Malvinas (Falklands) War of 1982 demonstrates this very well. In this war, two different types of armies confronted one another: the British army, a professional and all volunteer force, and the Argentine army constituted principally of conscripted soldiers. In this regard, some analysts assert that the British concept was vindicated when a force of British professional soldiers defeated an opposing Argentine force of draftees twice as numerous. Analysts in general have rated the capabilities of the Argentine land forces as poor, although there were exceptions and some units performed very well. These cases deserve to be studied. Notably, the most effective Argentine effort came from some small Army units and one Navy unit, the 5th Marine Battalion. For these units, two primary reasons account for the differences in fighting performance. First, small Army groups fought well because there was cohesion among their components, conscripts, noncommissioned officers, and junior officers, especially by the attitude of the latter. Secondly, in the case of the Marine battalion, its performance was the product not only of good training, but also of the different institutional approach to waging war that the Argentine Navy employed. These, in turn, improved cohesion. By focusing upon these units and their effectiveness, a rather new picture of the Malvinas War comes to light that differs quite substantially from those drawn in the immediate aftermath of the war itself. It should also make us rethink the lessons of the war, including those that surround the professionals versus conscripts controversy

    Bayesian Methods for Exoplanet Science

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    Exoplanet research is carried out at the limits of the capabilities of current telescopes and instruments. The studied signals are weak, and often embedded in complex systematics from instrumental, telluric, and astrophysical sources. Combining repeated observations of periodic events, simultaneous observations with multiple telescopes, different observation techniques, and existing information from theory and prior research can help to disentangle the systematics from the planetary signals, and offers synergistic advantages over analysing observations separately. Bayesian inference provides a self-consistent statistical framework that addresses both the necessity for complex systematics models, and the need to combine prior information and heterogeneous observations. This chapter offers a brief introduction to Bayesian inference in the context of exoplanet research, with focus on time series analysis, and finishes with an overview of a set of freely available programming libraries.Comment: Invited revie
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