1,711 research outputs found

    T-helper cells as new players in ANCA-associated vasculitides

    Get PDF
    In anti-neutrophil cytoplasmic autoantibody-associated vasculitides (AAV), several observations support a key role of T-helper cells (CD4+ T cells) in disease pathophysiology. An expanded population of effector memory CD4+ T cells in AAV patients may contribute to tissue injury and disease progression. In addition, functional impairment of regulatory T cells (TRegs) is reported in AAV patients. A fraction of TRegs have the capacity to differentiate into Th17 cells in the context of a proinflammatory environment. Therefore, nonfunctionality of TRegs described in AAV patients may be caused by their conversion into IL-17-producing cells that may contribute to granulomatous vasculitis. Further investigations directed at the plasticity of TRegs in AAV patients are warranted

    Quantum statistics of overlapping modes in open resonators

    Full text link
    We study the quantum dynamics of optical fields in weakly confining resonators with overlapping modes. Employing a recently developed quantization scheme involving a discrete set of resonator modes and continua of external modes we derive Langevin equations and a master equation for the resonator modes. Langevin dynamics and the master equation are proved to be equivalent in the Markovian limit. Our open-resonator dynamics may be used as a starting point for a quantum theory of random lasers.Comment: 6 pages, corrected typo

    The Midpoint Rule as a Variational--Symplectic Integrator. I. Hamiltonian Systems

    Get PDF
    Numerical algorithms based on variational and symplectic integrators exhibit special features that make them promising candidates for application to general relativity and other constrained Hamiltonian systems. This paper lays part of the foundation for such applications. The midpoint rule for Hamilton's equations is examined from the perspectives of variational and symplectic integrators. It is shown that the midpoint rule preserves the symplectic form, conserves Noether charges, and exhibits excellent long--term energy behavior. The energy behavior is explained by the result, shown here, that the midpoint rule exactly conserves a phase space function that is close to the Hamiltonian. The presentation includes several examples.Comment: 11 pages, 8 figures, REVTe

    Positive-P and Wigner representations for quantum-optical systems with nonorthogonal modes

    Get PDF
    We generalize the basic concepts of the positive-P and Wigner representations to unstable quantum-optical systems that are based on nonorthogonal quasimodes. This lays the foundation for a quantum description of such systems, such as, for example an unstable cavity laser. We compare both representations by calculating the tunneling times for an unstable resonator optical parametric oscillator

    Field quantization for open optical cavities

    Get PDF
    We study the quantum properties of the electromagnetic field in optical cavities coupled to an arbitrary number of escape channels. We consider both inhomogeneous dielectric resonators with a scalar dielectric constant ϵ(r)\epsilon({\bf r}) and cavities defined by mirrors of arbitrary shape. Using the Feshbach projector technique we quantize the field in terms of a set of resonator and bath modes. We rigorously show that the field Hamiltonian reduces to the system--and--bath Hamiltonian of quantum optics. The field dynamics is investigated using the input--output theory of Gardiner and Collet. In the case of strong coupling to the external radiation field we find spectrally overlapping resonator modes. The mode dynamics is coupled due to the damping and noise inflicted by the external field. For wave chaotic resonators the mode dynamics is determined by a non--Hermitean random matrix. Upon including an amplifying medium, our dynamics of open-resonator modes may serve as a starting point for a quantum theory of random lasing.Comment: 16 pages, added references, corrected typo

    Changes in plant diversity in a water‑limited and isolated high‑mountain range (Sierra Nevada, Spain)

    Get PDF
    Open Access funding provided by University of Natural Resources and Life Sciences Vienna (BOKU). This study was funded by the Austrian Academy of Sciences (project MEDIALPS-Disentangling anthropogenic drivers of climate change impacts on alpine plant species: Alps vs. Mediterranean mountains).Supplementary Information The online version contains supplementary material available at https ://doi.org/10.1007/s0003 5-021-00246 -x.We thank Manfred Bardy-Durchhalter for managing the database, Imran Nadeem for discussing climate data preparation, and National Park and Andalusian Environmental Agency staff for their assistance in the field in 2015 and 2019, and answering our questions.Climate change impacts are of a particular concern in small mountain ranges, where cold-adapted plant species have their optimum zone in the upper bioclimatic belts. This is commonly the case in Mediterranean mountains, which often harbour high numbers of endemic species, enhancing the risk of biodiversity losses. This study deals with shifts in vascular plant diversity in the upper zones of the Sierra Nevada, Spain, in relation with climatic parameters during the past two decades. We used vegetation data from permanent plots of three surveys of two GLORIA study regions, spanning a period of 18 years (2001–2019); ERA5 temperature and precipitation data; and snow cover durations, derived from on-site soil temperature data. Relationships between diversity patterns and climate factors were analysed using GLMMs. Species richness showed a decline between 2001 and 2008, and increased thereafter. Species cover increased slightly but significantly, although not for endemic species. While endemics underwent cover losses proportional to non-endemics, more widespread shrub species increased. Precipitation tended to increase during the last decade, after a downward trend since 1960. Precipitation was positively related to species richness, colonisation events, and cover, and negatively to disappearance events. Longer snow cover duration and rising temperatures were also related to increasing species numbers, but not to cover changes. The rapid biotic responses of Mediterranean alpine plants indicate a tight synchronisation with climate fluctuations, especially with water availability. Thus, it rather confirms concerns about biodiversity losses, if projections of increasing temperature in combination with decreasing precipitation hold true.University of Natural Resources and Life Sciences Vienna (BOKU) - Austrian Academy of Science

    Bring it to the Pitch: Combining Video and Movement Data to Enhance Team Sport Analysis

    Get PDF
    Analysts in professional team sport regularly perform analysis to gain strategic and tactical insights into player and team behavior. Goals of team sport analysis regularly include identification of weaknesses of opposing teams, or assessing performance and improvement potential of a coached team. Current analysis workflows are typically based on the analysis of team videos. Also, analysts can rely on techniques from Information Visualization, to depict e.g., player or ball trajectories. However, video analysis is typically a time-consuming process, where the analyst needs to memorize and annotate scenes. In contrast, visualization typically relies on an abstract data model, often using abstract visual mappings, and is not directly linked to the observed movement context anymore. We propose a visual analytics system that tightly integrates team sport video recordings with abstract visualization of underlying trajectory data. We apply appropriate computer vision techniques to extract trajectory data from video input. Furthermore, we apply advanced trajectory and movement analysis techniques to derive relevant team sport analytic measures for region, event and player analysis in the case of soccer analysis. Our system seamlessly integrates video and visualization modalities, enabling analysts to draw on the advantages of both analysis forms. Several expert studies conducted with team sport analysts indicate the effectiveness of our integrated approach

    Molecular Recognition Force Spectroscopy for Probing Cell Targeted Nanoparticles In Vitro

    Get PDF
    In the development and design of cell targeted nanoparticle-based systems the density of targeting moieties plays a fundamental role in allowing maximal cell-specific interaction. Here, we describe the use of molecular recognition force spectroscopy as a valuable tool for the characterization and optimization of targeted nanoparticles toward attaining cell-specific interaction. By tailoring the density of targeting moieties at the nanoparticle surface, one can correlate the unbinding event probability between nanoparticles tethered to an atomic force microscopy tip and cells to the nanoparticle vectoring capacity. This novel approach allows for a rapid and cost-effective design of targeted nanomedicines reducing the need for long and tedious in vitro tests.The authors would like to acknowledge the Bioimaging Platform (i3S-INEB) for the support with atomic force microscopy. This work was financed by projects NORTE-01-0145-FEDER-000008 and NORTE-01-0145-FEDER-000012, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 - Operacional Programme for Competitiveness and Internationalisation (POCI), Portugal 2020; and by Portuguese funds through FCT (Fundação para a Ciência e a Tecnologia) in the framework of the projects UID/BIM/04293/ 2013, PTDC/CTM-NAN/115124/2009, and PTDC/CTMNAN/3547/2014. C.P. Gomes acknowledge FCT for her PhD scholarship SFRH/BD/79930/2011

    An electronic survey of preferred podcast format and content requirements among trainee emergency medicine specialists in four Southern African universities

    Get PDF
    CITATION: Ekambaram, K., et al. 2021. An electronic survey of preferred podcast format and content requirements among trainee emergency medicine specialists in four Southern African universities. African Journal of Emergency Medicine, 11(1): 3-9, doi:10.1016/j.afjem.2020.10.014.The original publication is available at https://www.sciencedirect.com/journal/african-journal-of-emergency-medicinestudy aims to explore the desired content, format and delivery characteristics of a potential educational, context- specific Southern African EM podcast, by investigating current podcast usages, trends and preferences among Southern African EM registrars of varying seniority. Methods: We developed an electronic survey - using a combination of existing literature, context-specific specialist-training guidance, and input from local experts – exploring preferred podcast characteristics among EM registrars from four Southern African universities. Results: The study’s response rate was 75%, with 24 of the 39 respondents being junior registrars. Ninety-four percent (94%) of respondents used EM podcasts as an educational medium: 64% predominantly using pod- casts to supplement a personal EM study program. The primary mode of accessing podcasts was via personal mobile devices (84%). Additionally, respondents preferred a shorter podcast duration (5–15 min), favoured multimedia podcasts (56%) and showed an apparent aversion toward recorded faculty lectures (5%). Eighty-two percent (82%) of respondents preferred context-specific podcast content, with popular topics including toxi- cology (95%), cardiovascular emergencies (79%) and medico-legal matters (74%). Just-in-Time learning proved an unpopular learning strategy in our study population, despite its substantial educational value. Conclusion: Podcast-usage proved to be near-ubiquitous among the studied Southern African EM registrars. Quintessentially, future context-specific podcast design should cater for mobile device-use, shorter duration podcasts, more video content, context-specific topics, and content optimised for both Just-in-Time learning.https://www.sciencedirect.com/science/article/pii/S2211419X20301312Publisher’s versio
    • …
    corecore