387 research outputs found

    The impacts of environmental warming on Odonata: a review

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    Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns

    Theory and simulation of quantum photovoltaic devices based on the non-equilibrium Green's function formalism

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    This article reviews the application of the non-equilibrium Green's function formalism to the simulation of novel photovoltaic devices utilizing quantum confinement effects in low dimensional absorber structures. It covers well-known aspects of the fundamental NEGF theory for a system of interacting electrons, photons and phonons with relevance for the simulation of optoelectronic devices and introduces at the same time new approaches to the theoretical description of the elementary processes of photovoltaic device operation, such as photogeneration via coherent excitonic absorption, phonon-mediated indirect optical transitions or non-radiative recombination via defect states. While the description of the theoretical framework is kept as general as possible, two specific prototypical quantum photovoltaic devices, a single quantum well photodiode and a silicon-oxide based superlattice absorber, are used to illustrated the kind of unique insight that numerical simulations based on the theory are able to provide.Comment: 20 pages, 10 figures; invited review pape

    Mathematical models for immunology:current state of the art and future research directions

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    The advances in genetics and biochemistry that have taken place over the last 10 years led to significant advances in experimental and clinical immunology. In turn, this has led to the development of new mathematical models to investigate qualitatively and quantitatively various open questions in immunology. In this study we present a review of some research areas in mathematical immunology that evolved over the last 10 years. To this end, we take a step-by-step approach in discussing a range of models derived to study the dynamics of both the innate and immune responses at the molecular, cellular and tissue scales. To emphasise the use of mathematics in modelling in this area, we also review some of the mathematical tools used to investigate these models. Finally, we discuss some future trends in both experimental immunology and mathematical immunology for the upcoming years

    Population mechanics: A mathematical framework to study T cell homeostasis

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    Unlike other cell types, T cells do not form spatially arranged tissues, but move independently throughout the body. Accordingly, the number of T cells in the organism does not depend on physical constraints imposed by the shape or size of specific organs. Instead, it is determined by competition for interleukins. From the perspective of classical population dynamics, competition for resources seems to be at odds with the observed high clone diversity, leading to the so-called diversity paradox. In this work we make use of population mechanics, a non-standard theoretical approach to T cell homeostasis that accounts for clone diversity as arising from competition for interleukins. The proposed models show that carrying capacities of T cell populations naturally emerge from the balance between interleukins production and consumption. These models also suggest remarkable functional differences in the maintenance of diversity in naïve and memory pools. In particular, the distribution of memory clones would be biased towards clones activated more recently, or responding to more aggressive pathogenic threats. In contrast, permanence of naïve T cell clones would be determined by their affinity for cognate antigens. From this viewpoint, positive and negative selection can be understood as mechanisms to maximize naïve T cell diversity

    A Comparison of Stimulus Set Size on Tact Training for Children with Autism Spectrum Disorder

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    Previous studies on skill acquisition have taught targets in stimulus sets composed of different numbers of stimuli. Although the rationale for selection of a stimulus set size is not clear, the number of target stimuli trained within a set is a treatment decision for which there is limited empirical support. The current investigation compared the efficiency of tact training in 4 stimulus set sizes, each of which included 12 stimuli grouped into (a) 4 sets of 3 stimuli, (b) 3 sets of 4 stimuli, (c) 2 sets of 6 stimuli, and (d) 1 set of 12 stimuli. Results of all 4 participants with autism spectrum disorder show tact training with larger (i.e., 6 and 12) stimulus set sizes was more efficient than training with smaller (i.e., 3 and 4) stimulus set sizes

    Theory and simulation of photogeneration and transport in Si-SiOx superlattice absorbers

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    Si-SiOx superlattices are among the candidates that have been proposed as high band gap absorber material in all-Si tandem solar cell devices. Owing to the large potential barriers for photoexited charge carriers, transport in these devices is restricted to quantum-confined superlattice states. As a consequence of the finite number of wells and large built-in fields, the electronic spectrum can deviate considerably from the minibands of a regular superlattice. In this article, a quantum-kinetic theory based on the non-equilibrium Green's function formalism for an effective mass Hamiltonian is used for investigating photogeneration and transport in such devices for arbitrary geometry and operating conditions. By including the coupling of electrons to both photons and phonons, the theory is able to provide a microscopic picture of indirect generation, carrier relaxation, and inter-well transport mechanisms beyond the ballistic regime

    Nanopore-based kinetics analysis of individual antibody-channel and antibody-antigen interactions

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    <p>Abstract</p> <p>Background</p> <p>The UNO/RIC Nanopore Detector provides a new way to study the binding and conformational changes of individual antibodies. Many critical questions regarding antibody function are still unresolved, questions that can be approached in a new way with the nanopore detector.</p> <p>Results</p> <p>We present evidence that different forms of channel blockade can be associated with the same antibody, we associate these different blockades with different orientations of "capture" of an antibody in the detector's nanometer-scale channel. We directly detect the presence of antibodies via reductions in channel current. Changes to blockade patterns upon addition of antigen suggest indirect detection of antibody/antigen binding. Similarly, DNA-hairpin anchored antibodies have been studied, where the DNA linkage is to the carboxy-terminus at the base of the antibody's Fc region, with significantly fewer types of (lengthy) capture blockades than was observed for free (un-bound) IgG antibody. The introduction of chaotropic agents and its effects on protein-protein interactions have also been observed.</p> <p>Conclusion</p> <p>Nanopore-based approaches may eventually provide a direct analysis of the complex conformational "negotiations" that occur upon binding between proteins.</p

    Propaganda in an Age of Algorithmic Personalization: Expanding Literacy Research and Practice

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    In this commentary, the author considers the rise of algorithmic personalization and the power of propaganda as they shift the dynamic landscape of 21st‐century literacy research and practice. Algorithmic personalization uses data from the behaviors, beliefs, interests, and emotions of the target audience to provide filtered digital content, targeted advertising, and differential product pricing to online users. As persuasive genres, advertising and propaganda may demand different types of reading practices than texts whose purpose is primarily informational or argumentative. Understanding the propaganda function of algorithmic personalization may lead to a deeper consideration of texts that activate emotion and tap into audience values for aesthetic, commercial, and political purposes. Increased attention to algorithmic personalization, propaganda, and persuasion in the context of K–12 literacy education may also help people cope with sponsored content, bots, and other forms of propaganda and persuasion that now circulate online

    Seroepidemiology of Human Bocavirus Infection in Jamaica

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    Human bocavirus (HBoV) is a newly identified human parvovirus. HBoV is associated with upper and lower respiratory tract infections and gastroenteritis in children. Little is known about the seroepidemiology of HBoV in populations in the Caribbean.In a cross-sectional study conducted at the University Hospital of the West Indies in Kingston, Jamaica, 287 blood samples were collected from pediatric patients and tested for the presence of HBoV-specific antibody using a virus-like-particle based enzyme-linked immunosorbent assay (ELISA).HBoV-specific antibodies were found to be present in 220/287 (76.7%) of samples collected from the pediatric population. Seroprevalence of HBoV was highest in those ≥2 years old. The seroepidemiological profile suggests that most children are exposed to HBoV during the first two years of life in Jamaica.HBoV infection is common in children in Jamaica. HBoV seroprevalence rates in the Caribbean are similar to those previously reported in other areas of the world
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