6,727 research outputs found

    Effects of periodic environmental hypoxia on predation of a tethered polychaete, Glycera americana: implications for trophic dynamics

    Get PDF
    Hypoxia and anoxia have significant deleterious ecological effects on living resources throughout many estuarine and marine ecosystems worldwide. Brief periods of low oxygen have the potential to facilitate transfer of benthic production to higher trophic levels as many benthic infaunal species have shallower sediment depth distributions during hypoxic events. In August-September 1994, a time-lapse camera equipped with a water quality datalogger was used to document in situ exploitation of a tethered prey organism (Glycera americana Leidy) by mobile fish and crustacean predators during alternating normoxia-hypoxia cycles in the York River, Virginia, USA. Based on photographic and diver observations, this hypoxia-induced benthic-pelagic transfer of production is more likely to occur when environmental dissolved oxygen concentrations rise above an apparent threshold between 1 and 2 ml 1(-1). When oxygen concentrations decline below approximately 1.5 ml 1(-1) (30% O-2 saturation), the response of the predator to increased prey availability is abruptly interrupted. There is no energy gain by the predator until oxygen concentrations rise above this critical threshold level. It is suggested that predators return to affected areas and resume feeding activity before stressed infauna are able to return to normal positions in the sediment

    Non-conventional digital signatures and their implementations – A review

    Full text link
    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-19713-5_36The current technological scenario determines a profileration of trust domains, which are usually defined by validating the digital identity linked to each user. This validation entails critical assumptions about the way users’ privacy is handled, and this calls for new methods to construct and treat digital identities. Considering cryptography, identity management has been constructed and managed through conventional digital signatures. Nowadays, new types of digital signatures are required, and this transition should be guided by rigorous evaluation of the theoretical basis, but also by the selection of properly verified software means. This latter point is the core of this paper. We analyse the main non-conventional digital signatures that could endorse an adequate tradeoff betweeen security and privacy. This discussion is focused on practical software solutions that are already implemented and available online. The goal is to help security system designers to discern identity management functionalities through standard cryptographic software libraries.This work was supported by Comunidad de Madrid (Spain) under the project S2013/ICE-3095-CM (CIBERDINE) and the Spanish Government project TIN2010-19607

    Locoregionally advanced oral cavity cancer: A propensity‐score matched analysis on overall survival with emphasis on the impact of adjuvant radiotherapy

    Full text link
    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146457/1/hed25185_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146457/2/hed25185.pd

    Intracellular trafficking and cellular uptake mechanism of PHBV nanoparticles for targeted delivery in epithelial cell lines

    Get PDF
    Indexación: Web of Science; Scopus; Scielo.Background: Nanotechnology is a science that involves imaging, measurement, modeling and a manipulation of matter at the nanometric scale. One application of this technology is drug delivery systems based on nanoparticles obtained from natural or synthetic sources. An example of these systems is synthetized from poly(3-hydroxybutyrate-co-3-hydroxyvalerate), which is a biodegradable, biocompatible and a low production cost polymer. The aim of this work was to investigate the uptake mechanism of PHBV nanoparticles in two different epithelial cell lines (HeLa and SKOV-3). Results: As a first step, we characterized size, shape and surface charge of nanoparticles using dynamic light scattering and transmission electron microscopy. Intracellular incorporation was evaluated through flow cytometry and fluorescence microscopy using intracellular markers. We concluded that cellular uptake mechanism is carried out in a time, concentration and energy dependent way. Our results showed that nanoparticle uptake displays a cell-specific pattern, since we have observed different colocalization in two different cell lines. In HeLa (Cervical cancer cells) this process may occur via classical endocytosis pathway and some internalization via caveolin-dependent was also observed, whereas in SKOV-3 (Ovarian cancer cells) these patterns were not observed. Rearrangement of actin filaments showed differential nanoparticle internalization patterns for HeLa and SKOV-3. Additionally, final fate of nanoparticles was also determined, showing that in both cell lines, nanoparticles ended up in lysosomes but at different times, where they are finally degraded, thereby releasing their contents. Conclusions: Our results, provide novel insight about PHBV nanoparticles internalization suggesting that for develop a proper drug delivery system is critical understand the uptake mechanism.https://jnanobiotechnology.biomedcentral.com/articles/10.1186/s12951-016-0241-

    Continual Conscious Bioluminescent Imaging in Freely Moving Mice

    Get PDF
    In vivo bioluminescent imaging allows the detection of reporter gene expression in rodents in real time. Here we describe a novel technology whereby we can generate somatotransgenic rodents with the use of a viral vector carrying a luciferase transgene. We are able to achieve long term luciferase expression by a single injection of lentiviral or adeno-associated virus vectors to newborn mice. Further, we describe whole body bioluminescence imaging of conscious mice in a noninvasive manner, thus enforcing the 3R’s (replacement, reduction, and refinement) of biomedical animal research

    A supersonic crowdion in mica: Ultradiscrete kinks with energy between 40^{40}K recoil and transmission sputtering

    Get PDF
    In this chapter we analyze in detail the behaviour and properties of the kinks found in an one dimensional model for the close packed rows of potassium ions in mica muscovite. The model includes realistic potentials obtained from the physics of the problem, ion bombardment experiments and molecular dynamics fitted to experiments. These kinks are supersonic and have an unique velocity and energy. They are ultradiscrete involving the translation of an interstitial ion, which is the reason they are called 'crowdions'. Their energy is below the most probable source of energy, the decay of the 40^{40}K isotope and above the energy needed to eject an atom from the mineral, a phenomenon that has been observed experimentallyComment: 28 pages, 15 figure
    corecore